FILM AND METHOD FOR PRODUCING A FILM

Description

[0001] The invention relates to a film, a method for producing a film, the use of a film for application to a target substrate and a method for producing an electrical functional element.

[0002] Combined input and output devices such as touchscreens, also known as sensor panels, have a wide range of applications. For example, touchscreens enable the control of a computer program by touching the touchscreen. Typically, a touch sensor panel, which detects touch, is arranged on a display element, such as a liquid crystal display. The touch sensor panel thus enables control of the image generated by the display element. Additional input devices such as a computer mouse or keyboard are therefore not required, or are only required for special applications. Due to their typically smooth surface, touch sensor panels are less susceptible to dirt and easier to clean than other input devices. They also enable intuitive operation for users.Therefore, touch sensors are widely used in mobile phones, especially smartphones, as well as PDAs, tablet computers, ATMs, ticket machines, gaming machines and game consoles, as well as in household appliances and motor vehicles.

[0003] To manufacture such touchscreens, touch sensors have traditionally been bonded to a target substrate, such as a display element, using a separate adhesive film. The adhesive film has a non-self-supporting adhesive layer sandwiched between two so-called liners. To apply a touch sensor, a liner of the adhesive film is removed in a first step, and the adhesive layer is then bonded to the touch sensor. In a second step, the remaining liner is removed, and the touch sensor is bonded to the target substrate. Since these manufacturing processes are typically performed manually, consistent manufacturing quality cannot always be guaranteed. For example, the exact positioning of the touch sensor during application to the target substrate is prone to errors.The individual work steps, especially the removal of the liners and the inclusion-free application of the adhesive layer to the touch sensor or the touch sensor to the target substrate, also require significant time and personnel expenditure. Especially in mass production, the provision of the individual precursors also requires significant logistical effort to ensure the most uninterrupted manufacturing process possible.

[0004] US 2015 / 199048 A1 describes a touch panel with a flexible, transparent substrate and a transparent, electrically conductive film. Individual layers within this touch panel are bonded together by a layer of optically clear adhesive (OCA).

[0005] US 2002 / 149572 A1 discloses a capacitive, transparent touch sensor which is connected to a target substrate via a layer of pressure-sensitive adhesive.

[0006] DE 10 2014 106 585 A1 describes a multi-layer body with a carrier layer on which at least one luminous means is arranged and which further comprises a decorative layer and an injection-molded plastic layer.

[0007] DE 10 2012 109 820 A1 describes a body manufactured by an in-mold process, which comprises a film with at least one electrical or electronic functional layer. This functional layer has at least one electrical connection in a contacting area.

[0008] US 2012 / 026107 A1 describes a touchscreen panel comprising a transparent substrate having a first surface and a second surface facing away from the first surface, with touch-sensitive cells arranged over the first surface. The touchscreen panel further comprises a decorative film.

[0009] DE 102005006074 A1 discloses a decorated injection-molded article with a multilayer film. The injection-molded article comprises a replicating lacquer layer that creates a visually perceptible effect.

[0010] The invention is based on the object of providing a film which avoids the disadvantages of the prior art.

[0011] This object is achieved by a film comprising a carrier substrate, an adhesion-promoting layer for applying the film to a target substrate and at least one electrically conductive layer, wherein the at least one electrically conductive layer forms an electrical functional structure in a functional area, wherein the at least one electrically conductive layer forms at least one contacting structure for contacting the electrical functional structure in at least one contacting area,and wherein the adhesion-promoting layer, when viewed perpendicular to a plane spanned by the carrier substrate, does not cover the at least one contacting region at least in some areas, or wherein the adhesion-promoting layer, when viewed perpendicular to a plane spanned by the carrier substrate, is applied over the entire surface. The at least one electrically conductive layer is arranged between the carrier substrate and the adhesion-promoting layer, or the adhesion-promoting layer is arranged on the side of the carrier substrate facing away from the at least one electrically conductive layer. Furthermore, the adhesion-promoting layer is arranged on the surface of the film, wherein the adhesion-promoting layer consists of a material,that is highly transparent after application to the target substrate and the adhesion-promoting layer is formed from a hot-melt adhesive or a radiation-curable adhesive. This object is further achieved by a method for producing a film, wherein the method comprises the following steps, which are carried out in particular in the following order: a) providing a carrier substrate; b) applying at least one electrically conductive layer to the carrier substrate, wherein the at least one electrically conductive layer forms an electrical functional structure in a functional region, wherein the at least one electrically conductive layer forms at least one contacting structure for contacting the electrical functional structure in at least one contacting region; c) applying an adhesion-promoting layer for applying the film to a target substrate in such a way,that the adhesion-promoting layer, when viewed perpendicular to a plane spanned by the carrier substrate, does not cover the at least one contacting region at least in some areas, or wherein the adhesion-promoting layer, when viewed perpendicular to a plane spanned by the carrier substrate, is applied over the entire surface, wherein in step c) the adhesion-promoting layer is applied such that the at least one electrically conductive layer is arranged between the carrier substrate and the adhesion-promoting layer, or in step c) the adhesion-promoting layer is arranged on the side of the carrier substrate facing away from the at least one electrically conductive layer, and wherein the adhesion-promoting layer is arranged on the surface of the film, wherein the adhesion-promoting layer consists of a material,that is highly transparent after application to the target substrate and the adhesion-promoting layer is formed from a hot-melt adhesive or a radiation-curable adhesive.

[0012] It has been shown that the film according to the invention improves the manufacturing process for electrical functional elements, such as touchscreens. The film according to the invention enables direct application of the film to a target substrate without further intermediate steps and / or further intermediate products. This enables a faster manufacturing process and a reduction in manufacturing costs. The fact that the adhesion-promoting layer does not cover at least one contacting region, at least in some areas, ensures that the electrical functional structure can be contacted securely and robustly after application of the film to the target substrate. Since the contacting region does not adhere to the target substrate in the areas without an adhesion-promoting layer, it is easily accessible for contacting.Compared to the use of an adhesive film with a non-self-supporting adhesive layer arranged between two so-called liners, waste can also be reduced because, for example, neither the error-prone and complex process of manually adapting the previously separate adhesive film to the target substrate nor the manual adaptation of the adhesive film to the touch sensor has to be carried out. This can further reduce manufacturing costs. The film according to the invention also enables industrial mass production. For example, it is possible to apply the film over the entire surface of a target substrate using hot lamination machines. During hot lamination, pressure and heat are applied to individual, particularly loose layers of a layer stack in order to permanently bond the individual layers of the layer stack to one another and thus create a composite body.The pressure and / or heat acts on the layer stack, for example, using flat tools. Alternatively or additionally, rollers can also be provided as tools, which apply pressure and / or heat to the layer stack as linear contact in a roller gap. This can further reduce the time, personnel, and logistical effort while ensuring consistent manufacturing quality. Thus, the invention makes it possible to manufacture electrical functional elements, such as a display with a touch sensor, cost-effectively while simultaneously enabling robust and secure contacting of the electrical functional structure, which, for example, provides the touch panel functionality.

[0013] In this context, a region is understood to mean a defined area of ​​a layer or film that, when viewed perpendicular to a plane spanned by the carrier substrate, is occupied. For example, the at least one electrically conductive layer has a functional region and at least one contacting region, with each of the regions occupying a defined area when viewed perpendicular to a plane spanned by the carrier substrate.

[0014] Further advantageous embodiments of the invention are described in the subclaims.

[0015] According to the invention, the at least one electrically conductive layer is arranged between the carrier substrate and the adhesion-promoting layer. Thus, it is possible for the adhesion-promoting layer to be arranged on the side of the at least one electrically conductive layer facing away from the carrier substrate. Thus, it is possible for the adhesion-promoting layer to be applied in step c) such that the at least one electrically conductive layer is arranged between the carrier substrate and the adhesion-promoting layer. Since the adhesion-promoting layer is arranged on the surface of the film, the film can be applied directly to a target substrate, further ensuring that the electrical functional structure can be reliably contacted.

[0016] According to the invention, it is alternatively possible for the adhesion-promoting layer to be arranged on the side of the carrier substrate facing away from the at least one electrically conductive layer. Thus, in step c), the adhesion-promoting layer can be arranged on the side of the carrier substrate facing away from the at least one electrically conductive layer.

[0017] Preferably, the adhesion-promoting layer is applied over the entire surface when viewed perpendicular to a plane spanned by the carrier substrate. Advantageously, the adhesion-promoting layer is thus arranged in the functional area and the contacting area. Furthermore, it is possible for the adhesion-promoting layer to be applied over the entire surface of the carrier substrate in such a way that no further layers are arranged between the carrier substrate and the adhesion-promoting layer.

[0018] Preferably, the adhesion-promoting layer covers the functional area at least in part. Thus, in step c), the adhesion-promoting layer can be applied in such a way that the adhesion-promoting layer covers the functional area at least in part. This ensures that the functional area adheres to the target substrate.

[0019] Adhesion is understood here as the adhesion of the film to the target substrate such that a predefined minimum adhesive force is achieved, which enables secure adhesion of the film to the target substrate. The adhesive force is at least so strong that the film cannot be separated from the intermediate or final product comprising the applied film and the target substrate during intended use. However, the adhesive force is not necessarily so strong that the film cannot be separated from the target substrate even with great force, such as by tearing it off. It is therefore possible that the adhesive force is such that the film can be mechanically separated from the target substrate without damaging the target substrate or the film.

[0020] Advantageously, the adhesion-promoting layer covers the functional area by at least 30%, preferably by at least 50%, more preferably by at least 70%.

[0021] Furthermore, it is possible for the adhesion-promoting layer not to fully cover the at least one contacting area. This makes it possible for the adhesion-promoting layer not to fully cover the at least one contacting area when viewed perpendicular to the plane spanned by the carrier substrate. This enables secure and robust contacting of an electrical functional structure, which, for example, provides the touch panel functionality.

[0022] It is advantageous that the adhesion-promoting layer, when viewed perpendicular to a plane spanned by the carrier substrate, does not cover an area adjacent to the at least one contacting area.

[0023] Furthermore, it is advantageous for the region adjacent to the at least one contacting region to have a width of at least 0.2 mm, preferably of at least 0.5 mm, more preferably of at least 1 mm, and even more preferably of at least 2 mm. Width here refers to the distance between the interface formed by the at least one contacting region and the one region adjacent to the at least one contacting region, and the interface formed by the adhesion-promoting layer and the one region adjacent to the at least one contacting region.

[0024] This facilitates contacting the electrical functional structure because the area in which the film does not adhere to the target substrate is enlarged. Since this area directly borders the contacting area, it is possible, for example, to lift the film in the contacting area during a contacting process, making the contacting structure more accessible and thus further facilitating contacting. It is thus possible for the area adjacent to the at least one contacting area to be movable such that the at least one contacting area can be lifted.

[0025] According to a further embodiment of the invention, the adhesion-promoting layer is a layer of polymers and / or copolymers, in particular comprising polymethyl (meth)acrylate (PMMA), polyester, polyurethane (PU) or polyvinyl chloride (PVC).

[0026] Less preferably, the adhesion-promoting layer comprises natural resins, preferably rosin, phenolic resins, isocyanate (NCO)-crosslinked binders, for example melamine-formaldehyde condensation resins (MF), melamine-phenol-formaldehyde resins (MPF), melamine polyesters, melamine-urea-formaldehyde resins (UMF), poly(organo)siloxanes or radiation-curing binders.

[0027] Binders are substances that can bind solids, especially those with a fine degree of particle size, together or to a substrate. Thus, the binders can be added in liquid form to the solids to be bound.

[0028] Advantageously, the adhesion-promoting layer has a layer thickness between 0.1 µm and 50 µm, preferably between 0.25 µm and 25 µm, more preferably between 0.5 µm and 7 µm.

[0029] It is further advantageous if the adhesion-promoting layer comprises one or more layers. For example, it is possible for the adhesion-promoting layer to comprise two layers, in particular a first adhesion-promoting layer and a second adhesion-promoting layer. This makes it possible to optimize the adhesion of the film to the target substrate. For example, the second adhesion-promoting layer, which is arranged in particular between the first adhesion-promoting layer and the target substrate, can be matched to the material of the target substrate, wherein the first adhesion-promoting layer is matched to the material of the layer of the film adjacent to the first adhesion-promoting layer, for example a protective lacquer layer. By suitable selection of the first and second adhesion-promoting layers, the adhesion of the film to the target substrate can thus be optimized.

[0030] According to the invention, the adhesion-promoting layer consists of a material that is highly transparent after application of the film to the target substrate, in particular that the adhesion-promoting layer consists of a material that, after application of the film to the target substrate, has a light transmission in the wavelength range between 380 nm and 780 nm of more than 85%, preferably more than 90%. This can, for example, ensure that light emitted by the target substrate in the wavelength range between 380 nm and 780 nm is not significantly reduced in intensity by the adhesion-promoting layer. Furthermore, optical information of the target substrate is clearly recognizable through the film applied to the target substrate. This can, for example, ensure that the resolution and color reproduction of a display to which the film is applied is not changed for a human observer.

[0031] The adhesion-promoting layer may, in particular, have a cloudy visual appearance in the state not yet applied to the target substrate and thus not (yet) be highly transparent. The cloudy appearance may arise, for example, from differences in the refractive index of the adhesion-promoting layer and the surrounding air and / or from surface roughness of the adhesion-promoting layer, in particular on the side of the adhesion-promoting layer facing away from the at least one electrically conductive layer. The surface roughness may, in particular, scatter incident light and thereby create a cloudy impression. Such surface roughness may arise, in particular, during the application of the adhesion-promoting layer due to the application methods used. For example, the surface roughness may be formed by a printing pattern of a gravure anilox roller or a screen printing tool.After the film has been applied to the target substrate, however, the adhesion-promoting layer is highly transparent, as the adhesion-promoting layer is then melted, particularly by hot lamination, and / or leveled by pressure to such an extent that the surface roughness of the adhesion-promoting layer is no longer disruptive. Depending on the refractive index of the target substrate, the refractive index difference between the adhesion-promoting layer and the adjacent material can also be eliminated. As a result, the optical interface between the adhesion-promoting layer and the target substrate is no longer visible.

[0032] Transparent refers to the property of a material to transmit light from the wavelength range visible to the human eye, particularly from the wavelength range between 380 nm and 780 nm. The term "highly transparent" therefore describes the property of a material to barely attenuate light from the wavelength range visible to the human eye, particularly from the wavelength range between 380 nm and 780 nm, and to transmit it essentially unhindered. A highly transparent layer therefore exhibits essentially no discernible light absorption for a human observer, so that the light intensity is barely discernibly reduced when light passes through the layer.

[0033] In this context, cloudy refers to the property of matter that prevents light from the wavelength range visible to the human eye, particularly from the wavelength range between 380 nm and 780 nm, from passing through it unhindered. A cloudy layer, for example, prevents light from passing through it unhindered due to scattering properties. Light can also be absorbed and / or reflected in a cloudy layer. For example, a cloudy layer can create a milky optical impression for a human observer, so that additional layers located beneath a cloudy layer are perceived as smeared and / or obscured.

[0034] Furthermore, it is advantageous for the adhesion-promoting layer to consist of a material that is clear after application of the film to the target substrate, in particular for the adhesion-promoting layer to consist of a material that, after application of the film to the target substrate, deflects light in the wavelength range between 380 nm and 780 nm by less than 8%, preferably by less than 4%, through scattering. This can, for example, ensure that an image generated by a target substrate, such as a display, is essentially not influenced by the film applied to the target substrate for a human observer. The low scattering of the material of the adhesion-promoting layer and thus of the adhesion-promoting layer itself can ensure that an image generated by a display is not perceived as blurred or smeared by a human observer when the film is applied to the display.This allows a brilliant and true-to-original view of the image generated by the display through the film, particularly in the case of high-resolution displays with pixel densities of more than 200 ppi (ppi = pixels per inch).

[0035] As previously described, the adhesion-promoting layer, when not yet applied to the target substrate, may exhibit light-scattering properties due to surface roughness of the adhesion-promoting layer, resulting in a cloudy visual appearance. The adhesion-promoting layer becomes clear, particularly when the film is applied to the target substrate and the adhesion-promoting layer is melted and / or leveled, for example, by means of heat and / or pressure applied during hot lamination, so that the surface roughness of the adhesion-promoting layer is no longer disruptive. This means that physical and / or chemical changes to the adhesion-promoting layer during or after application of the film to the target substrate render the adhesion-promoting layer highly transparent and / or clear.

[0036] According to the invention, the adhesion-promoting layer is formed from a hot-melt adhesive or a radiation-curable adhesive, in particular an adhesive curable by electromagnetic radiation and / or electron beams. It is further disclosed that the adhesion-promoting layer, in an embodiment not covered by the claimed subject matter, can be formed from a cold-curing adhesive.

[0037] Furthermore, it is possible for the adhesion-promoting layer to be patterned, in particular in the form of a rectangle, rounded rectangle, or motif. Thus, it is possible for the pattern of the patterned adhesion-promoting layer to be adapted to the structures of the target substrate.

[0038] It is also possible for the adhesion-promoting layer to be applied according to a grid, particularly a one-dimensional or two-dimensional grid. Thus, it is possible for the adhesion-promoting layer to be applied according to a dot or line grid. During application of the film to the target substrate, the grid formed by the adhesion-promoting layer is smoothed so that the transparency of the film is not negatively affected by the adhesion-promoting layer applied according to the grid.

[0039] Advantageously, after application to the target substrate, the film has, at least in the one functional region of the at least one electrically conductive layer, a transmission of light in the wavelength range between 380 nm and 780 nm of more than 75%, preferably more than 80%, more preferably more than 85%, even more preferably more than 90%.

[0040] The transmittance describes the permeability of the film for light in the wavelength range between 380 nm and 780 nm. Light incident on the film is partially reflected at the air-film interface and at the interfaces between the film layers. Furthermore, the light incident on the film is partially absorbed as it passes through the film. The remaining portion of the light is transmitted through the film and exits again on the opposite side of the film. To determine the transmittance τ, the quotient of the light intensity behind the film I and the light intensity in front of the film I 0 is calculated. The transmittance τ is a measure of the "transmitted" intensity and takes values ​​between 0 and 1. The transmittance typically depends on the wavelength of the incident light. Therefore, the wavelength range is specified next to the transmittance values.

[0041] As previously described, the adhesion-promoting layer may have a cloudy visual appearance prior to application of the film to a target substrate, for example due to surface roughness. These surface roughnesses are leveled out, particularly during the application process, so that the adhesion-promoting layer is highly transparent and / or clear after application to the target substrate. The cloudy visual impression of the adhesion-promoting layer disappears, and the film as a whole, at least in the one functional region of the at least one electrically conductive layer, exhibits a light transmission in the wavelength range between 380 nm and 780 nm of more than 75%, preferably more than 80%, more preferably more than 85%, and even more preferably more than 90%.As will be explained later, it is advantageous if the film is applied to a target substrate with known transmission and then the total transmission of the electrical functional element formed from the target substrate and the film is determined.

[0042] According to a further embodiment of the invention, the film comprises a release layer, wherein the release layer, when viewed perpendicular to a plane spanned by the carrier substrate, at least partially covers the at least one contacting region. Thus, it is possible for the method to further comprise the following steps: e) applying a release layer such that, when viewed perpendicular to a plane spanned by the carrier substrate, the release layer, when viewed perpendicular to a plane spanned by the carrier substrate, at least partially covers the at least one contacting region. Thus, it is possible for the release layer to prevent the at least one contacting region from adhering.

[0043] Furthermore, it is advantageous that the carrier substrate and / or the at least one electrically conductive layer and / or the release layer and / or the protective lacquer layer is / are transparent.

[0044] It is also possible that the release layer completely covers at least one contact area.

[0045] Furthermore, it is possible for the release layer to cover the area adjacent to the at least one contacting area.

[0046] The release layer can further ensure that the film does not adhere to the target substrate in areas that have the release layer. The release layer can thus prevent the at least one contacting area from adhering to the target substrate, in particular, prevent the at least one contacting area from adhering to the target substrate due to the hot lamination of the film to the target substrate.

[0047] The release layer preferably consists of waxes, polyethylene (PE), polypropylene (PP), cellulose derivatives, or poly(organo)siloxanes. The aforementioned waxes can be natural waxes, synthetic waxes, or combinations thereof. Examples of such waxes include carnauba waxes. Examples of such cellulose derivatives include cellulose acetate (CA), cellulose nitrate (CN), cellulose acetate butyrate (CAB), or mixtures thereof. Examples of such poly(organo)siloxanes include silicone binders, polysiloxane binders, or mixtures thereof.

[0048] Less preferably, the release layer comprises natural resins, preferably rosin, phenolic resins, halogen-containing homopolymers, for example polyvinyl chloride (PVC), polyvinyl fluoride (PVF), polytetrafluoroethane (PTFE), polyvinylidene fluoride (PVDF) or polyvinylidene chloride (PVDC), polyesters, for example polybutylene terephthalate (PBT), polycyclohexylenedimethylene terephthalate (PCT), polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), polycarbonate (PC), polyester carbonate (PEC), polyacrylates (PAC) or unsaturated polyester resin (UP), polymeric carboxylic acid esters, for example polymethyl (meth)acrylates (PMMA), isocyanate (NCO)-crosslinked binders, for example melamine-formaldehyde condensation resins (MF), melamine-phenol-formaldehyde resins (MPF), melamine polyester, Melamine-urea-formaldehyde resins (UMF), polyolefins other than PP or PE, for example polymethylpentene (PMP), polyisobutylene (PIB) or polybutylene (PB),Copolymers consisting of PVC, PMMA, PU, ​​poly(organo)siloxanes and polyolefins that are not PP or PE.

[0049] Less preferably, the release layer further comprises radiation-curing binders.

[0050] The release layer preferably has a layer thickness between 0.1 µm and 10 µm, more preferably between 0.1 µm and 5 µm. This low layer thickness is advantageous to enable electrical contacting of the at least one contacting area covered by the release layer, in particular by means of adapter elements and / or connecting elements and / or contact elements, such as contact springs, ZIF connectors (ZIF = Zero Insertion Force), crimp contacts, crimp-flex contacts, ACF bonding (Anisotropic Conductive Film) or a conductive rubber multiple connection (ZEBRA). Advantageously, the release layer is locally penetrated during electrical contacting, in particular by the adapter elements and / or connecting elements and / or contact elements, so that the release layer no longer locally exerts an effect that hinders electrical contacting, in particular an electrically insulating effect.It is advantageous if the electrically insulating release layer is destroyed by mechanical-physical forces during contacting, in particular by the adapter elements and / or connecting elements and / or contact elements, in such a way that electrical conductivity is created, in particular between the at least one contacting area and the adapter elements and / or connecting elements and / or contact elements. This is achieved, for example, by contact springs or crimping. Furthermore, ZIF contacting is also mechanically "cutting," thus enabling electrical contacting of the at least one contacting area covered by the release layer. With ACF bonding, metal pigments in the adhesive layer can penetrate the release layer during pressing / embossing of the film, thus enabling electrical contacting using ACF bonding.

[0051] Furthermore, it is also possible that electrical contact does not necessarily have to be established through a galvanic connection between the at least one contacting area and the adapter elements and / or connecting elements and / or contact elements and / or the contact layer, in particular of the target substrate. It is also possible for electrical contact to be achieved via a capacitive coupling of two contact surfaces, such as between the at least one contacting area and a target contacting area, in particular a contact layer of the target substrate, with at least one insulating layer arranged therebetween.

[0052] According to a further embodiment of the invention, the film comprises a protective lacquer layer.

[0053] Advantageously, the protective lacquer layer covers the at least one electrically conductive layer at least in regions when viewed perpendicular to a plane spanned by the carrier substrate. Furthermore, it is advantageous that the following step is performed between step b) and step c): - applying a protective lacquer layer, in particular such that the protective lacquer layer covers the at least one electrically conductive layer at least in regions when viewed perpendicular to a plane spanned by the carrier substrate. This makes it possible for the protective lacquer layer to protect the at least one electrically conductive layer from mechanical, physical, and / or chemical environmental influences.

[0054] It is also possible for the protective lacquer layer to completely cover the at least one electrically conductive layer when viewed perpendicular to a plane spanned by the carrier substrate in the functional area.

[0055] It is also possible that the film contains one or more layers of protective varnish.

[0056] In particular, protective lacquer layers which form the outermost layer of the film or of an intermediate or final product, in particular of an electrical

[0057] Functional element to which the film has been applied, protect the other layers of the film from mechanical, physical and / or chemical environmental influences or influences of further process steps.

[0058] It is advantageous that the protective lacquer layer has a layer thickness between 0.1 µm and 50 µm, preferably between 0.25 µm and 25 µm, more preferably between 0.5 µm and 15 µm.

[0059] Preferably, the protective lacquer layer is a transparent protective lacquer layer, in particular made of PMMA, polyester, PU or PVC.

[0060] Less preferably, the protective lacquer layer comprises natural resins, preferably rosin, phenolic resins, isocyanate (NCO)-crosslinked binders, for example MF, MPF, melamine polyester, UMF, polyolefins which are not PP or PE, for example PMP, PIB or PB.

[0061] It is also advantageous for the protective lacquer layer to be arranged between the at least one electrically conductive layer and the adhesion-promoting layer. It is also possible for the protective lacquer layer to be applied such that the protective lacquer layer is arranged between the at least one electrically conductive layer and the adhesion-promoting layer. Thus, it is possible for the protective lacquer layer to be arranged on the side of the at least one electrically conductive layer facing away from the carrier substrate.

[0062] It is also possible that the film has a structure in the following order: Carrier substrate at least one electrically conductive layer protective lacquer layer adhesion promoter layer.

[0063] Furthermore, it is possible for the protective lacquer layer to be arranged between the at least one electrically conductive layer and the carrier substrate. The electrically conductive layer is embedded and protected between the protective lacquer layer and the adhesion-promoting layer. The protective lacquer layer and the adhesion-promoting layer preferably consist of lacquers with similar physical properties, particularly with regard to mechanical deformability and extensibility. This makes it possible for the embedded electrically conductive layer to be protected from damage, for example, tearing, in the event of significant deformation of the film, thus maintaining its electrical functionality. The embedding of the electrically conductive layer as described above also prevents delamination of these layers.

[0064] It is also possible for the film to comprise a primer layer, in particular a primer layer that can be vapor-deposited for metallization. Advantageously, the primer layer is arranged between the protective lacquer layer and the at least one electrically conductive layer.

[0065] Advantageously, the primer layer is a layer of polymers and / or copolymers, in particular comprising polymethyl (meth)acrylate (PMMA), polyester, polyurethane (PU) or polyvinyl chloride (PVC).

[0066] Less preferably, the primer layer comprises natural resins, preferably rosin, phenolic resins, isocyanate (NCO)-crosslinked binders, for example melamine-formaldehyde condensation resins (MF), melamine-phenol-formaldehyde resins (MPF), melamine polyesters, melamine-urea-formaldehyde resins (UMF), poly(organo)siloxanes or radiation-curing binders.

[0067] The primer coat layer preferably has a layer thickness between 0.1 µm and 5 µm, preferably between 0.1 µm and 2 µm.

[0068] It is also possible that the film has a structure in the following order: Carrier substrate, protective lacquer layer, primer lacquer layer, at least one electrically conductive layer, adhesion promoter layer.

[0069] It is also advantageous if the film is a transfer film.

[0070] Advantageously, a transfer film comprises a carrier layer, in particular the carrier substrate, and a transfer layer that can be detached from the carrier layer, in particular the carrier substrate.

[0071] Advantageously, a separating layer is arranged between the carrier layer, in particular the carrier substrate, and the transfer layer, which allows the transfer layer to be detached from the carrier layer, in particular the carrier substrate.

[0072] This makes it possible to apply only the transfer layer to a target substrate, in particular by hot stamping.

[0073] However, it is also possible that the carrier layer, in particular the carrier substrate, is not detached after application to the target substrate, so that the carrier layer, in particular the carrier substrate, also remains on the target substrate.

[0074] It is also possible for the film to comprise a release layer. The release layer may be a single-layer or multi-layer release layer. The release layer is preferably arranged between the carrier substrate and the protective lacquer layer. This makes it possible, for example, for the carrier substrate to be removed after the film has been applied to the target substrate. This allows for even better deformability and / or extensibility of the applied film, since the comparatively thick and less deformable and / or extensible carrier substrate has been removed. The protective lacquer layer performs the function of protecting the film.

[0075] The release layer is preferably a wax layer and / or a polymer layer made of, for example, acrylates and / or melamine-formaldehyde resin-crosslinked lacquers. The release layer preferably has a layer thickness of less than 1 µm. The layer structure of the film does not necessarily have to correspond to the layer structure according to claim 1.

[0076] Advantageously, it can be provided that the adhesive force between the carrier substrate and the protective lacquer layer is 20% to 80%, preferably 30% to 70%, smaller than the adhesive force between the protective lacquer layer and the primer lacquer layer and / or the at least one electrically conductive layer and / or the adhesion-promoting layer due to the separating layer arranged between the carrier substrate and the protective lacquer layer.

[0077] It is therefore possible that the adhesive force between the carrier substrate and the protective lacquer layer is 20% to 80%, preferably 30% to 70%, lower than the adhesive force between the layers of the transfer layer, in particular selected from the group consisting of a protective lacquer layer, a primer lacquer layer, at least one electrically conductive layer, one or more decorative layers, an adhesion promoter layer, an intermediate adhesive layer, a dielectric layer, a darkening layer and a contact reinforcement layer, due to the release layer arranged between the carrier substrate and the protective lacquer layer. The adhesive forces were determined using the Zwick Z005 tensile testing machine from Zwick GmbH & Co. KG, Ulm, Germany. For this purpose, the transfer film was adhered flat to the lower holder. The layer to be removed was then removed at a right angle using the tensile test. The removal forces were determined using the load cell.

[0078] So it is possible that the film has a structure in the following order: Carrier substrate, separating layer, protective lacquer layer, primer layer, at least one electrically conductive layer, adhesion promoter layer.

[0079] Even with the transfer film variant, since the adhesion-promoting layer does not cover the at least one contact area, the electrical functional structure can be contacted after application of the film to the target substrate, so that an electrical connection can be established, for example, using the contacting methods mentioned above. The optional release layer also enables the carrier substrate to be at least partially removed, which further improves the possibility of subsequent contacting, since the film in this variant does not adhere to the edge of the carrier substrate.

[0080] Furthermore, it is possible, especially after removing the carrier substrate, to apply a reinforcing element in order to increase the mechanical stability of the applied transfer layers.

[0081] According to a further embodiment, the target substrate has a contact layer, in particular for electrically contacting the at least one contacting region of the film.

[0082] Preferably, the contact layer is applied directly to the target substrate.

[0083] Furthermore, it is possible that the contact layer has at least one connecting element.

[0084] Furthermore, it is also possible that the contact layer has at least one adapter element and / or contact element.

[0085] Preferably, the Zielsubstrat thus already has at least one connecting element and / or adapter element and / or contact element, in particular for electrically contacting the at least one contacting area of ​​the film.

[0086] Advantageously, the contact layer is arranged in at least one target contact area of ​​the target substrate. Preferably, the at least one target contact area of ​​the target substrate forms the counterpart to the at least one contact area of ​​the film. Thus, it is advantageous that the at least one target contact area of ​​the target substrate and the at least one contact area of ​​the film are congruent, preferably after application of the film to the target substrate, in particular that the at least one target contact area of ​​the target substrate and the at least one contact area of ​​the film overlap at least in some areas after application of the film.

[0087] Furthermore, it is possible for the target substrate to comprise at least one third electrically conductive layer. Preferably, the at least one third electrically conductive layer has a plurality of conductor tracks. Thus, it is possible for the at least one third electrically conductive layer to have electrically conductive structures, in particular conductor tracks, which are preferably arranged according to a grid. This grid can be regular or irregular. The grid can, in particular, be constructed from grid elements, such as lines and / or surface elements.

[0088] Furthermore, it is also possible for the at least one third electrically conductive layer to have further electrical components.

[0089] Advantageously, the at least one third electrically conductive layer of the target substrate is electrically connected to the at least one contact layer.

[0090] For example, it is possible for the target substrate to be equipped with conductor tracks and / or other electrical components. These conductor tracks can then advantageously be electrically connected to other electrical components in a known manner using plug contacts or other known contacting methods. This can preferably be done using laser direct structuring (LDS) or printed contacts, in particular screen-printed contacts, or a contact layer applied, for example, by lamination and / or hot or cold stamping. For example, it is possible for the target substrate to be a type of printed circuit board.

[0091] This makes it possible to use the contact layer to electrically connect the at least one third electrically conductive layer of the target substrate to the functional area of ​​the electrically conductive layer of the foil via the foil's contacting area. The contact layer on the target substrate thus forms the mating contact to the foil's contacting area.

[0092] Furthermore, it is advantageous if the contact layer, in particular the at least one connecting element and / or adapter element and / or contact element, and / or the at least one third electrically conductive layer is / are produced and / or applied by means of laser direct structuring (LDS) and / or by means of printing, in particular by means of screen printing.

[0093] Furthermore, it is also possible that the contact layer, in particular the at least one connecting element and / or adapter element and / or contact element, is applied by means of lamination and / or hot stamping or cold stamping.

[0094] Furthermore, it is possible for the contact layer, in particular the at least one connecting element and / or adapter element and / or contact element on the target substrate, to be formed from an electrically conductive paste, in particular carbon paste, which comprises silver (Ag), gold (Au), aluminum (Al), copper (Cu), chromium (Cr), and / or other conductive metals. Furthermore, it is possible for the electrically conductive paste, in particular carbon paste, to comprise binders, in particular comprising rosin and / or phenolic resins, polymers, and copolymers. Binders of the electrically conductive paste, in particular carbon paste, are natural resins, preferably rosin, phenolic resins, polymers, and copolymers consisting of PVC, PMMA, PU, ​​polyester, and isocyanate (NCO)-crosslinked binders, for example, MF, MPF, melamine-polyester, and UMF. Less preferred are binders of the electrically conductive paste comprising poly(organo)siloxanes and their copolymers and / or radiation-curing binders.

[0095] Furthermore, it is possible for the film in the at least one contact area to be fully or partially printed with an adhesive varnish in a pattern, for example, in a grid. Thus, it is possible for the film to have an adhesive varnish in the at least one contact area.

[0096] Alternatively, it is also possible that the film does not have the adhesive varnish in at least one contact area or that the adhesive varnish is completely omitted locally in the area of ​​the contacts.

[0097] When the film is applied to the target substrate provided with the contact layer, an electrical (pressure) contact (through heat and pressure) is preferably created between the film and the target substrate, particularly in the at least one contact area and / or target contact area. It is possible that the electrical (pressure) contact is permanent due to the bonding, particularly the adhesive varnish.

[0098] It is also possible to insert an ACF bonding tape between the at least one contact area of ​​the film and the at least one target contact area of ​​the target substrate. This can further improve the electrical connection in the contact area. It is advantageous if the application process (heat and pressure) largely corresponds to the conventional ACF bonding process.

[0099] Furthermore, it is advantageous if the contact layer of the target substrate is designed such that two or more films can be applied to the target substrate. This makes it possible for the contact layer of the target substrate to have connecting elements and / or adapter elements and / or contact elements for electrically contacting at least two films.

[0100] It is also possible for the target substrate to have the contact layer for contacting a first film in a first target contacting region and the contact layer for contacting a second film in a second target contacting region.

[0101] Advantageously, the target substrate to which at least two films are to be applied already has a contact layer which is designed in such a way that a two-layer sensor consisting of a film for the x-layer and a film for the y-layer can be applied.

[0102] It is also possible for the target substrate to which the at least two films are to be applied to already contain, as described above, electrical contacts and contact leads for a two-layer sensor consisting of an x-layer and a y-layer. Preferably, the x-layer and y-layer are each formed from a film according to the invention. First, the first sensor layer, for example the x-layer, is preferably applied to the target substrate using the film according to the invention, and the electrical contact is established. Advantageously, the first sensor layer is applied to the target substrate in precise registration with the contact layer, in particular the at least one connecting element and / or adapter element and / or contact element, of the target substrate for electrical contacting, in particular the first sensor layer.

[0103] Thus, it is possible that in a first step a first film is applied to the target substrate in such a way that the at least one contacting region of the first film overlaps at least partially with the target contacting region of the contact layer for contacting the first film.

[0104] Preferably, in a separate step, the second sensor layer, for example the y-layer, is then applied using the film according to the invention in precise registration with the first sensor layer or in precise registration with the contact layer, in particular the at least one connecting element and / or adapter element and / or contact element, of the target substrate for electrical contacting, in particular the second sensor layer, on the target substrate. In this case, it is possible to omit adhesive bonding, for example using OCA, between the sensor layers. The registration accuracy, i.e. the positional accuracy of the second sensor layer relative to the first sensor layer, is preferably ±350 µm, more preferably ±150 µm, in the x- and y-directions in order to achieve the desired functionality of the sensor.

[0105] Thus, it is possible that in a second step a second film is applied to the target substrate in such a way that the at least one contacting region of the second film overlaps at least partially with the target contacting region of the contact layer for contacting the second film.

[0106] Preferred embodiments of the at least one contacting region and / or the at least one contacting structure are described below, among other things.

[0107] Preferably, the at least one contacting structure for contacting the electrical functional structure is an electrical connection, in particular a plug.

[0108] Advantageously, the at least one electrically conductive layer has a contact reinforcement layer.

[0109] Furthermore, it is advantageous that the at least one electrically conductive layer has the contact reinforcement layer in the at least one contacting region at least in some areas, wherein the contact reinforcement layer protects the at least one contacting region from mechanical, physical and / or chemical environmental influences.

[0110] It is thus possible that the following step is carried out between step b) and step c): - applying a contact reinforcement layer (7) such that the at least one electrically conductive layer (3) has a contact reinforcement layer (7), in particular that the at least one electrically conductive layer (3) has the contact reinforcement layer (7) in the at least one contacting region (20) at least in some regions.

[0111] The contact reinforcement layer improves the resistance / durability of the at least one contacting area, as the contacting area is protected from corrosion or scratching, for example. Furthermore, the mechanical stability of the contacting area, in particular the bending and / or buckling stability, can also be improved.

[0112] Furthermore, it is possible for the contact reinforcement layer to completely cover at least one contacting area.

[0113] It is also possible for the at least one contacting area to have one or more contacting areas separated from one another. Separated here means that the contacting areas are spaced apart from one another, in particular that the contacting areas are spaced apart by at least 0.1 mm, preferably at least 0.2 mm, more preferably at least 0.5 mm.

[0114] Furthermore, it is advantageous that the contact reinforcement layer has a layer thickness between 0.1 µm and 100 µm, preferably between 0.25 µm and 25 µm, more preferably between 0.5 µm and 10 µm.

[0115] It is possible for the contact reinforcement layer to be formed from an electrically conductive paste, in particular carbon paste, comprising silver (Ag), gold (Au), aluminum (Al), copper (Cu), chromium (Cr), and / or other conductive metals. Furthermore, it is possible for the electrically conductive paste, in particular carbon paste, to comprise binders, in particular including rosin and / or phenolic resins, polymers, and copolymers.

[0116] Binders for the electrically conductive paste, especially carbon paste, are natural resins, preferably rosin, phenolic resins, polymers and copolymers consisting of PVC, PMMA, PU, ​​polyester, isocyanate (NCO)-crosslinked binders, for example, MF, MPF, melamine-polyester, UMF. Less preferred are binders for the electrically conductive paste comprising poly(organo)siloxanes and their copolymers and / or radiation-curing binders.

[0117] It is advantageous that the adhesion promoter layer, the protective lacquer layer, the release layer and / or the contact reinforcement layer is / are applied by means of gravure printing, screen printing, letterpress printing or casting techniques.

[0118] Preferred embodiments of the at least one electrically conductive layer and / or the electrical functional structure are described below, among others: According to a further embodiment of the invention, the electrical functional structure forms a touch sensor field, in particular a capacitive sensor field, which provides touch field functionality. It is also possible for the electrical functional structure to form a resistive or inductive sensor field.

[0119] A touch sensor panel is defined as a touch-sensitive sensor that enables the control of an electrical functional element, such as a PDA. A touch sensor panel is also defined as a multi-touch sensor panel that can process multiple simultaneous touches, for example, for enlarging and rotating images displayed on a display, particularly one located below the touch sensor panel.

[0120] In a preferred embodiment, it is provided that the film comprises at least two electrically conductive layers, in particular a first electrically conductive layer and a second electrically conductive layer.

[0121] Advantageously, the at least two electrically conductive layers are arranged at least partially overlapping when viewed perpendicular to a plane spanned by the carrier substrate.

[0122] This makes it possible, in particular, to produce multi-layer touch sensors that can also process multiple simultaneous touches, for example, for enlarging and rotating images. For example, the second electrically conductive layer can be provided on a second carrier film, which is applied, in particular glued, to the first conductive layer, in particular by means of the adhesion-promoting layer and / or an intermediate adhesive layer and / or with the aid of primer layers and / or adhesive layers. These primer layers and / or adhesive layers can be formed from a hot-melt adhesive, a cold-melt adhesive, or a radiation-curable adhesive, in particular an adhesive curable by means of electromagnetic radiation and / or electron beams.

[0123] When applying the second electrical layer to the first electrically conductive layer, it is expedient if the relative positioning of the two electrically conductive layers is carried out in precise register with one another, in particular with a tolerance of less than 0.25 mm, preferably with a tolerance of less than 0.1 mm, in order to provide undisturbed touch functionality. It is thus possible for the at least two electrically conductive layers to be arranged in precise register with one another, in particular for the at least two electrically conductive layers to be arranged with a tolerance of less than 0.25 mm, preferably less than 0.1 mm, to one another. The electrically conductive layers in particular have electrically conductive structures, in particular conductor tracks, which are preferably arranged according to a grid. This grid can be regular or irregular.The grid can be constructed, in particular, from grid elements, such as lines and / or area elements. The grid elements can form so-called sensor cells.

[0124] According to a further embodiment of the invention, the at least one electrically conductive layer and / or the two electrically conductive layers have a plurality of conductor tracks.

[0125] Conductor tracks are understood here to mean preferably structured electrically conductive layers and conductive regions of the at least one electrically conductive layer and / or the two electrically conductive layers. The conductor tracks are applied in particular in such a way that sufficient transparency for the human eye is maintained; i.e., the conductor tracks are designed in such a way that they are not perceived by a human observer, since the conductor tracks are below the resolution of the human eye. Despite the narrow conductor tracks used, sufficient electrical conductivity is achieved, which is comparable in particular to layers made of indium tin oxide (ITO).Preferably, the coverage of the carrier substrate with the at least one electrically conductive layer, in particular the conductor tracks, is less than 30%, preferably less than 20%, more preferably less than 10%, even more preferably less than 5%.

[0126] Advantageously, the conductor tracks are spaced apart from one another, in particular the conductor tracks have a width between 0.2 µm and 20 µm, preferably between 4 µm and 15 µm, and a distance greater than 10 µm, preferably greater than 20 µm, from one another, so that the conductor tracks are below the resolution of the human eye.

[0127] It is advantageous if the conductor tracks of the first electrically conductive layer and the second electrically conductive layer are each arranged according to a line grid, wherein in particular the line grids are rotated by 90° relative to each other. Thus, the first and second electrically conductive layers each have a line grid of spaced-apart conductor tracks. The first and second electrically conductive layers are preferably arranged one above the other such that both line grids are arranged at right angles, i.e., rotated by 90° relative to each other. Electrical supply lines and / or contacting elements are preferably provided in the edge regions of both line grids.Preferably, these edge regions are arranged with a tolerance of less than 0.25 mm, preferably less than 0.1 mm, in register accuracy relative to one another, in particular in the direction of the coordinate axes x and y, wherein the coordinate axes x and y span a plane which lies parallel to a plane spanned by the carrier substrate.

[0128] In a further preferred embodiment, the conductor tracks of the first electrically conductive layer and the second electrically conductive layer are structured, in particular structured such that the conductor tracks of the first electrically conductive layer and the second electrically conductive layer form a plurality of surface elements, preferably rhombus-shaped or diamond-shaped surface elements. For example, it is possible for the first and second electrically conductive layers to each have a so-called diamond structure. This diamond structure is formed by a plurality of, in particular, rhombus-shaped surface elements along linear conductor tracks. The first and second electrically conductive layers each have a plurality of spaced-apart diamond structures.The first and second electrically conductive layers are arranged one above the other such that both diamond structures are arranged at right angles to each other, i.e., rotated 90° to each other. The surface elements of the first electrically conductive layer are arranged "on the gap" in the free spaces between the surface elements of the second electrically conductive layer. The linear conductor tracks of the electrically conductive layers intersect in the spaces between the surface elements. In this preferred embodiment, a precise position of the surface elements relative to each other is particularly important, and the surface elements are advantageously arranged with a tolerance of less than 0.25 mm, preferably less than 0.1 mm, in register accuracy relative to each other, particularly in the x- and y-coordinate directions.

[0129] In this case, it is possible for the conductor tracks in the region of the surface elements to be shaped according to the shape of the surface elements, so that the material from which the electrically conductive layer is formed fills the surface elements over their entire surface. Furthermore, it is possible for the conductor tracks to run along the surface elements, so that the conductor tracks frame the surface elements at least in some areas. The surface elements can thus be formed from a full-surface conductive layer or from a region-specific, in particular gridded, electrically conductive layer made up of conductive grid elements and, in particular, transparent, non-conductive surface areas between the grid elements. The grid forming the grid elements can be regular or irregular. In particular, the surface elements can be semi-transparent due to the grid and have a surface coverage with grid elements of less than 50%.

[0130] Furthermore, it is also possible that the electrically conductive structures of the first and second conductive layers formed by the structured electrically conductive layers and / or the conductive regions of the electrically conductive layers each have different geometries and / or sizes.

[0131] Advantageously, the contacting areas, in particular the contacting structures, of the at least two electrically conductive layers are combined in a common contacting area. This makes it possible to facilitate external contacting.

[0132] Furthermore, it is possible for the common contacting area to be electrically contacted by means of an adapter element. For example, it is possible for a particularly flexible adapter element to be attached to the common contacting area, which adapter element electrically contacts the contact points in the common contacting area and connects them externally in an electrically conductive manner to a further contact element. The contact between the common contacting area and the adapter element is preferably made by means of conductive adhesive, in particular by means of ACF bonding (ACF = Anisotropic Conductive Film). In this case, it is possible for the conductive adhesive to represent a connecting element. The further contact element can, for example, be a particularly standardized connector, for example a ZIF connector (ZIF = Zero Insertion Force).

[0133] It is advantageous for the conductor tracks to be made of metal, in particular silver (Ag), gold (Au), aluminum (Al), copper (Cu), or chromium (Cr), with a layer thickness between 1 nm and 100 nm, preferably between 2.5 nm and 75 nm, more preferably between 5 nm and 50 nm. However, it is also possible for the conductor tracks to have a layer thickness between 100 nm and 5 µm.

[0134] It is also possible that the conductor tracks are formed from an electrically conductive paste comprising silver (Ag), gold (Au), copper (Cu) and / or carbon.

[0135] Furthermore, or additionally, it is possible for the at least one electrically conductive layer to comprise at least one layer of ITO (InSnO x = indium tin oxide = In 2 O 3 :SnO 2 ) and / or of AZO (AlZnO x = aluminum zinc oxide = Al:ZnO). The ITO and / or AZO layers are preferably applied over the entire surface by magnetron sputtering, sputtering, or (vacuum) vapor deposition, and less preferably by CVD and PVD processes, and preferably have a layer thickness of 1 nm to 100 µm, more preferably of 10 nm to 10 µm.

[0136] Preferably, the ITO and / or AZO layers are arranged directly adjacent to electrically conductive layers made of metallic materials.

[0137] Advantageously, in step b), the at least one electrically conductive layer is a metal layer, and step b) further comprises the following steps: - vapor deposition of the metal layer; - structuring the metal layer by removing the metal layer in certain areas, in particular using photolithographic techniques. Thus, to form the at least one electrically conductive layer, the carrier substrate is preferably provided with an electrically conductive layer over its entire surface, for example by vapor deposition or sputtering of a metal layer, and then the electrically conductive layer is removed again in certain areas by positive or negative etching or by means of a washing process, in accordance with the formation of the electrical functional structure and contacting structure.Furthermore, it is also possible that by means of vapor deposition masks, by printing electrically conductive material and / or by galvanically reinforcing a printed structure, the at least one electrically conductive layer is already applied to the carrier substrate in the shape according to the functional structure and / or contacting structure.

[0138] Preferably, the film comprises a dielectric layer and / or a semiconducting layer which is arranged between a first electrically conductive layer of the at least one electrically conductive layer and a second electrically conductive layer of the at least one electrically conductive layer.

[0139] Furthermore, it is possible for the at least one electrically conductive layer to have force sensors, in particular for measuring the compressive force. This makes it possible to determine, in addition to the x and y coordinates of the position of the touch on the plane defined by the x and y coordinates, for example, generated by a touch sensor field, in particular by a capacitive sensor field, the touch intensity in the form of the z coordinate (the z coordinate is perpendicular to the x and y coordinates). This makes it possible to generate x, y, and z information about the touch. The z information can be used, for example, to control an electrical functional element to which the film is applied, depending on whether a predefined threshold value of the z information is exceeded. Piezoelectric thin films are preferred for force sensors, in particular for measuring the compressive force.It is also possible for force sensors to be piezoresistive pressure sensors and / or piezoelectric pressure sensors. Furthermore, it is possible for force sensors to be actuators, in particular pushbuttons, where each of the actuators has at least two electrical states depending on the force acting on the actuators.

[0140] Furthermore, it is possible for the at least one electrically conductive layer to have surface relief structures, in particular matte structures, at least in some regions. This makes it possible to deflect light incident on the at least one electrically conductive layer by diffraction, scattering, and / or reflection, thus avoiding the impression that the electrically conductive layer reflects light, in particular by direct specular reflection. For example, a display to which the film is applied appears homogeneously black when switched off.

[0141] It is also possible for one or more optically active layers, in particular darkening layers and / or layers with light-scattering properties, to cover / cover the at least one electrically conductive layer at least in part when viewed perpendicular to a plane spanned by the carrier substrate. This can further reduce the possible visibility of the at least one electrically conductive layer, in particular in direct specular reflection. For example, a darkening layer absorbs incident light, thereby reducing the proportion of light reflected by the at least one electrically conductive layer or preventing reflection altogether. Layers with light-scattering properties also reduce the proportion of light reflected by the at least one electrically conductive layer.

[0142] Layers with light-scattering properties are, for example, layers that have matte structures with stochastically selected relief parameters.

[0143] It is also advantageous for the carrier substrate to have a layer thickness between 2 µm and 250 µm, preferably between 23 µm and 125 µm. However, it is also possible for the carrier substrate to have a layer thickness of less than 2 µm.

[0144] Advantageously, the film has a total thickness of at most 150 µm, preferably 100 µm, more preferably 75 µm, perpendicular to the plane spanned by the underside of the carrier substrate.

[0145] Preferably, the carrier substrate is a transparent carrier substrate, in particular made of PET, PMMA, PC, acrylonitrile butadiene styrene (ABS), PU or glass.

[0146] It is possible that the carrier substrate is formed from a hybrid material comprising plastic layers and layers of fiber material.

[0147] It is also possible that the carrier substrate consists of fabrics, for example textile fabrics.

[0148] Furthermore, it is possible for the target substrate to be a single- or multi-layer film. In this case, the application of the film according to the invention to the target substrate in the form of the single- or multi-layer film preferably produces an intermediate product for further processing.

[0149] According to a further embodiment of the invention, the film comprises at least one intermediate adhesive layer. This makes it possible to apply one or more additional layers to the film, with the adhesion of the one or more additional layers being achieved by the intermediate adhesive layer.

[0150] Preferably, the at least one electrically conductive layer is arranged between the carrier substrate and the at least one intermediate adhesive layer.

[0151] Furthermore, it is possible for the at least one intermediate adhesive layer to be arranged on the side of the carrier substrate facing away from the at least one electrically conductive layer. Thus, it is possible for the method to further comprise the following steps: f) applying an intermediate adhesive layer, in particular such that the at least one electrically conductive layer is arranged between the carrier substrate and the at least one intermediate adhesive layer and / or such that the at least one intermediate adhesive layer, when viewed perpendicular to a plane spanned by the carrier substrate, does not cover the at least one contacting region, at least in some regions.

[0152] It is also advantageous if the at least one intermediate adhesive layer, when viewed perpendicular to a plane spanned by the carrier substrate, does not cover the at least one contacting area, at least in part. The fact that the intermediate adhesive layer does not cover the at least one contacting area, at least in part, ensures that the electrical functional structure can be contacted securely and robustly after the film is applied to the target substrate.

[0153] It is also advisable if the intermediate adhesive layer does not completely cover at least one contact area.

[0154] Furthermore, it is advantageous if the intermediate adhesive layer covers the functional area at least in part.

[0155] It is also possible that the at least one intermediate adhesive layer is arranged substantially in the same region as the adhesion-promoting layer when viewed perpendicular to a plane spanned by the carrier substrate, in particular that the at least one intermediate adhesive layer is arranged substantially congruent with the adhesion-promoting layer when viewed perpendicular to a plane spanned by the carrier substrate.

[0156] The intermediate adhesive layer advantageously has a layer thickness between 0.1 µm and 50 µm, preferably between 0.25 µm and 25 µm, more preferably between 0.5 µm and 7 µm. The intermediate adhesive layer is preferably a primer layer and / or adhesive layer made of a hot-melt adhesive, a cold-melt adhesive, or a radiation-curable adhesive, in particular an adhesive curable by electromagnetic radiation and / or electron beams. The intermediate adhesive layer is preferably applied using gravure printing, screen printing, letterpress printing, or casting techniques.

[0157] It is also possible for the film to include one or more decorative layers.

[0158] Preferably, the one or more decorative layers are arranged on the side of the carrier substrate facing away from the at least one electrically conductive layer. For this purpose, the film can, in particular, comprise an intermediate adhesive layer to improve the adhesion of the one or more decorative layers. For example, an intermediate adhesive layer can be applied to the carrier substrate and / or the at least one electrically conductive layer, by means of which the one or more decorative layers are applied to the carrier substrate. The decorative layers can then be applied to the intermediate adhesive layer or directly to the carrier substrate using various methods.It is particularly advantageous if the decorative layers have a protective layer as a final layer on the side of the carrier substrate facing away from the at least one electrically conductive layer. This protective layer protects the decorative layers, in particular, from the strong pressure and heat effects that occur, for example, during injection molding and / or lamination processes. Furthermore, the protective layer protects against mechanical damage that may occur during processing, such as scratches, etc. This protective layer can also contain polymeric and, in particular, self-supporting films, preferably made of PET, PC, or PMMA, or even of glass or fabric, which remain on the decoration and form a component of the intermediate or final product.

[0159] Advantageously, the one or more decorative layers are arranged substantially in the same region as the adhesion-promoting layer and / or the intermediate adhesive layer, in particular the one or more decorative layers are arranged substantially congruent with the adhesion-promoting layer and / or the intermediate adhesive layer when viewed perpendicular to a plane spanned by the carrier substrate.

[0160] It is thus possible for the one or more decorative layers to be partially applied to the side of the carrier substrate facing away from the at least one electrically conductive layer in such a way that they cover substantially the same area as the adhesion promoter layer on the other side of the carrier substrate. This ensures that the contacting region uncovered by the adhesion promoter layer on the side of the carrier substrate facing away from the at least one electrically conductive layer remains free in the same (projected) surface area, allowing the film to form a so-called tail with the contacting region, which can be electrically contacted in a particularly simple manner in subsequent processing steps, for example, by means of a plug connection.

[0161] It is also possible that the one or more decorative layers are arranged on the side of the adhesion-promoting layer and / or the intermediate adhesive layer facing away from the carrier substrate.

[0162] Furthermore, it is also possible for the one or more decorative layers to be arranged on the side of the at least one electrically conductive layer facing away from the carrier substrate.

[0163] The one or more decorative layers are preferably applied substantially congruently with the adhesion-promoting layer, leaving, in particular, the at least one contacting area uncovered. Here, too, it can be advantageous if the decorative layers have a protective layer as a final layer on the side of the at least one electrically conductive layer and / or the intermediate adhesive layer facing away from the carrier substrate. This protective layer protects the decorative layers, in particular, from the strong pressure and heat effects that occur, for example, during injection molding and / or lamination processes. Furthermore, the protective layer protects against mechanical damage that may occur during processing, such as scratches, etc.This protective layer can also contain polymeric and in particular self-supporting films, preferably made of PET, PC or PMMA, or also of glass or fabric, which remain on the decoration and form a component of the final product.

[0164] Advantageously, the at least one intermediate adhesive layer is arranged between the carrier substrate and the one or more decorative layers.

[0165] Preferably, the one or more decorative layers comprise at least one of the layers selected from the group of protective layers, colored lacquer layers, metal layers, reflective layers, replication lacquer layers, transparent layers, carrier layers and / or layers generating an optically variable effect.

[0166] For example, the one or more decorative layers can comprise a printed layer, in particular made of an opaque and / or colored ink, which forms a frame around the functional area. The decorative layers can also fully or partially cover the film and in particular also the functional area and / or be applied in a grid. The decorative layers can represent a uniform surface and / or a continuous pattern and / or a single image motif. The decorative layers can be fully or partially opaque and / or semi-transparent and / or transparent, in particular colored transparent.

[0167] For example, it is possible for one or more decorative layers to be applied, in particular embossed and / or printed, to the adhesion-promoting layer and / or the intermediate adhesive layer. The one or more decorative layers can be applied, for example, by hot stamping and / or cold stamping and / or by thermal transfer processes and / or by various lamination processes and / or other known processes to the side of the adhesion-promoting layer and / or the intermediate adhesive layer facing away from the carrier substrate. This makes it possible, for example, to provide the film with a decorative layer or a decoration, so that the film additionally has a decoration in addition to a function provided by the electrical functional structure in the form of a touch sensor field.The one or more decorative layers may comprise additional layers, such as protective lacquer layers and / or color layers and / or metal layers and / or transparent reflective layers and / or replicating lacquer layers and / or various types of layer structures generating an optically variable effect. The layer structure of the film does not necessarily have to correspond to the layer structure according to claim 1.

[0168] Furthermore, it is possible that the one or more decorative layers comprise at least two decorative layers, in particular a first decorative layer and a second decorative layer.

[0169] It is also possible for the one or more decorative layers to be arranged on the side of the carrier substrate facing away from the at least one electrically conductive layer and also on the side of the at least one electrically conductive layer facing away from the carrier substrate. For example, it is possible for a first decorative layer to be arranged on a first side of the carrier substrate and a second decorative layer to be arranged on a side of the carrier substrate opposite the first side, so that the one or more decorative layers are arranged on both sides of the carrier substrate.

[0170] Furthermore, it is advantageous if at least two decorative layers interact in such a way that special optical effects, such as optical depth effects and / or special optical overlay effects, are created. For example, the first decorative layer facing the viewer can represent a color filter layer for the second decorative layer facing away from the viewer, i.e., lying below it in the direction of view, which is, for example, a color layer. Overlay effects or combination effects are also possible using two patterns that complement each other to form a moiré pattern or, when superimposed, create other complementary combination patterns.

[0171] Furthermore, optically variable combination effects are possible, which only arise through the superimposition of at least two decorative layers. It can be advantageous for the decorative layers to be spaced apart from one another, for example because the carrier substrate and the electrically conductive layer and optionally further layers, in particular transparent layers, are arranged between the decorative layers. Such a spacing can be advantageous in particular for creating depth effects and / or optically variable effects. A depth effect can be created, for example, by inserting optically transparent layers in front of the decorative layers and / or behind the decorative layers and / or as part of the decorative layers.The optically transparent layers preferably have the same thickness as the respective decorative layers or a layer thickness that is several times thicker than the respective decorative layers. In particular, the layer thickness of the optically transparent layers is between 0.5 µm and 500 µm, preferably between 10 µm and 100 µm. The optically transparent layers preferably consist of optically transparent lacquers and / or optically transparent films, preferably made of PET, PMMA, or PC.

[0172] An optically variable effect is possible, for example, by arranging the aforementioned optically transparent layer as a spacer layer between a reflective layer and a semitransparent reflective layer, and by creating interference effects within this layer structure, which are recognizable by a viewing-angle-dependent and / or illumination-angle-dependent color change effect. Such interference layer structures are already known as Fabry-Perot thin-film structures.

[0173] It is further advantageous if at least one of the one or more decorative layers has, at least in some areas, a surface relief structure, in particular a haptically and / or tactilely detectable surface relief structure.

[0174] It is also possible for surface morphologies, in particular surface relief structures, to be created by structuring the optically transparent layers and / or the protective layers and / or the one or more decorative layers, which in particular enable haptic or tactile effects. Furthermore, it is also possible for the surface relief structures to create diffractive and / or refractive optical effects. These surface relief structures can be created by additional partially printed varnishes or mechanical structuring or optical structuring of the layer surface. Mechanical structuring can be replication using a suitably shaped embossing tool. Optical structuring can be laser ablation. Photolithographic processes can also be used to create these structures.The structural depths for such haptic effects are in particular 1 µm to 2000 µm, preferably 50 µm to 2000 µm. The structural depths for diffractive or refractive effects are in particular 0.1 µm to 20 µm, preferably 0.1 µm to 5 µm.

[0175] It is also possible to merely simulate such haptic surface relief structures because real haptic structures are often mechanically sensitive, particularly to scratching and / or wear, and also become soiled more easily than smooth surfaces. For this purpose, it is advisable, as described above, to incorporate the haptic structures into and / or apply them to a corresponding surface. A transparent cover layer can then be applied to this surface, which seals the haptic structure and has a smooth surface on the outside. This cover layer is preferably highly transparent and thicker than the height of the haptic structures, preferably at least twice as thick. Furthermore, the cover layer preferably has a refractive index that differs by at least 0.2 from that of the underlying layer containing the haptic structure, in order to create an optical interface, thereby increasing the visibility of the haptic structure.For this purpose, the cover layer can contain nanoscale particles for modulating the refractive index consisting of one or more components selected from TiO 2 , SiO 2 , Sn or metal chalcogenides (oxides, sulfides), as well as metals Au, Ag, Cu.

[0176] The tactile and / or merely optically simulated haptic surface relief structure can correspond to the functional touch sensor fields, i.e., highlight or mark their functional area, enabling a "blind" perception of the touch function. However, it is equally possible for the tactile and / or merely optically simulated haptic structure to be provided over the entire surface in order to achieve a specific surface characteristic of the target substrate, in particular matching its overall visual appearance. Both options can also be combined. For example, it is possible to combine a wood decor with a haptic wood grain that is modified in the area of ​​the touch function, particularly in the functional area, in terms of structure depth and / or another structural parameter, so that the touch sensor field can be felt by a user within the grain.

[0177] It is also possible that the film has a structure in the following order: Carrier substrate, separating layer, protective lacquer layer, primer lacquer layer, at least one electrically conductive layer, intermediate adhesive layer, one or more decorative layers, adhesion promoter layer.

[0178] It is also possible for the film to have an adhesive layer on the side of the carrier substrate facing away from the at least one electrically conductive layer.

[0179] The film can thus have the adhesion-promoting layer on one side of the carrier substrate and the adhesive layer on the other side of the carrier substrate, so that the film can be applied to a further substrate by means of the adhesive layer. The film can be applied to the further substrate, for example, by hot lamination or by back-injection molding. In particular, when the film is back-injected, the at least one electrically conductive layer and / or the one or more decorative layers are protected by the carrier substrate from the injected injection molding compound and in particular from the harsh process conditions of high pressure and high temperature during the injection molding process. The layer structure of the film does not necessarily have to correspond to the layer structure according to claim 1.

[0180] It is further advantageous if the film has at least one register mark for determining the relative position of the film, in particular of the functional area and / or of the at least one contacting area of ​​the at least one electrically conductive layer. Register or register accuracy is understood to mean the precise arrangement of layers lying one above or next to one another while maintaining a desired positional tolerance. A register mark can thus ensure that the film can be applied to a target substrate in a precise position while maintaining a desired positional tolerance. The register mark is preferably formed from a printing material and / or from a magnetic or conductive material. The marks can thus be, for example, optically readable register marks that differ from the background in terms of their color value, opacity or reflective properties.The register marks can also be detectable by a magnetic sensor or a sensor that detects electrical conductivity. The register marks are detected, for example, by an optical sensor, in particular a camera, a magnetic sensor, a mechanical sensor, a capacitive sensor, or a sensor that detects conductivity. The application of the film can then be controlled using the register marks. The register marks thus enable the precise positioning of the film on the target substrate. This can improve the identical manufacturing quality of touchscreens, for example, and at the same time further reduce rejections due to incorrect placement of the film on the target substrate.

[0181] Preferably the film is a hot lamination film.

[0182] The following describes, among other things, preferred embodiments of the method for producing an electrical functional element and of the electrical functional element: It is also advantageous that in step b) the film is applied from a roll to the target substrate by means of hot lamination, in particular at a film web speed of between 1.5 m / min and 3.5 m / min. In this case, it is possible for the roll to comprise a film web with several or a large number of films, in particular according to one of claims 1 to 53, as a panel. This makes it possible to further improve, in particular, industrial mass production. For example, it is possible to apply the film over the entire surface of a target substrate using a hot lamination machine, so that the time, personnel and logistical expenditure can be further reduced and, at the same time, identical manufacturing quality can be ensured.

[0183] It is further advantageous that, in step b), the film is applied from a sheet to the target substrate by hot lamination. In this case, it is possible for the sheet to comprise several or a plurality of films, in particular according to one of claims 1 to 53, as a panel. This makes it possible, in particular, to further improve industrial mass production. For example, it is possible to apply the film over the entire surface of a target substrate using a hot lamination machine, thus further reducing the time, personnel, and logistical effort while simultaneously ensuring identical manufacturing quality.

[0184] It is also possible for the sheet to comprise only one film as a single panel. Several such sheets, each with one film, can be stacked in a magazine and fed individually to a hot laminator, which can operate using a stroke or roll-off process, and / or an injection molding machine for application to the target substrate. The registration marks on the film then ensure precise positioning on the target substrate, as described above.

[0185] It is also advantageous if individual one or more films are arranged in a detachable manner on an intermediate substrate, which can be in the form of a roll or sheet, prior to application to the target substrate. The intermediate substrate can be, for example, a silicone-coated paper or a film web provided with a release layer. In a subsequent heat transfer step and / or in a subsequent injection molding process, one or more films can then be transferred jointly or separately from the intermediate substrate to the target substrate by applying heat and / or pressure. The intermediate substrate can then be peeled off, in particular from the film firmly adhering to the target substrate.

[0186] It is further possible for the hot lamination to take place at a temperature in the range between 80°C and 300°C, preferably between 200°C and 290°C, more preferably between 240°C and 270°C, and / or with an embossing pressure in the range between 200 bar and 2000 bar, preferably between 500 bar and 1500 bar.

[0187] As an alternative to hot lamination in step b), it is also possible to apply the film to the target substrate by injecting an injection-molding compound, with the injection-molding compound in particular forming the target substrate. This allows the film to be firmly bonded to the injection-molding compound by the adhesion-promoting layer.

[0188] It is also possible for the film to be bonded to another substrate by injecting an injection-molding compound. The layer structure of the film does not necessarily have to correspond to the layer structure according to claim 1.

[0189] Furthermore, it is advantageous, especially when the film is designed as a transfer film, for the film to be applied to the target substrate by hot stamping in step b). In this case, the film can be applied to the target substrate by hot stamping from a roll or from a sheet.

[0190] It is possible for the roll to comprise a film web with several or a plurality of films as panels, and / or for the sheet to comprise several or a plurality of films as panels. This makes it possible to further improve, particularly for industrial mass production. For example, it is possible to apply the film over the entire surface of a target substrate using a hot stamping machine, thus further reducing the time, personnel, and logistical effort while ensuring consistent manufacturing quality.

[0191] It is further expedient if the embossing temperature is in a range from 80°C to 250°C, preferably in a range from 100°C to 200°C, and / or the embossing pressure is in a range from 0.5 kN / cm 2 to 10 kN / cm 2 . Furthermore, it is also expedient if the embossing time is in a range from 1 ms to 2000 ms, preferably in a range from 1 ms to 500 ms.

[0192] Furthermore, it is possible that the further substrate and / or the target substrate is flat and / or has a one-dimensionally curved and / or a two-dimensionally curved and / or a three-dimensionally curved shape.

[0193] It is also possible for the film and / or the electrical functional element, in particular the electrical functional element formed from the target substrate and the film, to be formed, in particular three-dimensionally formed. The forming advantageously takes place by means of forming processes, preferably by means of deep drawing, thermoforming, high-pressure forming, and / or an injection molding process. The target substrate and / or intermediate substrate preferably has a maximum layer thickness of 1 mm, preferably 500 µm, so that the electrical functional element formed from the film and the target substrate is formable.

[0194] The following describes, among other things, preferred forming processes for forming the film and / or the electrical functional element, wherein, in particular, the electrical functional element is formed from the film arranged, in particular applied, on a target substrate: Preferably, the film and / or the electrical functional element is formed by deep drawing. Advantageously, the forming of the film and / or the electrical functional element is carried out by means of a vacuum, in particular at a negative pressure of a maximum of 1 bar, and / or by means of overpressure support, in particular at an overpressure between 1 bar and 3 bar, in a forming tool corresponding to the desired forming geometry.

[0195] Furthermore, it is possible for the film and / or the electrical functional element to be formed by thermoforming. Advantageously, the forming process of the film and / or the electrical functional element, or the process parameters of the forming process, correspond to those of deep drawing, with the forming taking place with additional temperature support, in particular at a temperature between 120 °C and 300 °C, preferably between 190 °C and 250 °C, for example, when using ABS material. In this case, it is possible for either the carrier substrate and / or the target substrate to comprise ABS material.

[0196] It is also possible for the film and / or the electrical functional element to be formed using high-pressure forming. Advantageously, the forming of the film and / or the electrical functional element is carried out using overpressure support, in particular at an overpressure between 1 bar and 300 bar, preferably between 10 bar and 150 bar, in a forming tool corresponding to the desired forming geometry. It is expedient for the forming to be carried out with additional temperature support, preferably at temperatures in the range of the glass transition temperature of the film used. Advantageously, the temperature is between 120°C and 300°C, preferably between 190°C and 250°C, for example when using ABS material.

[0197] Using the above-mentioned forming processes, three-dimensional elongations of up to 200% are preferably achieved. It is also possible, especially when the parameters are optimized for the respective system, to achieve elongations of up to 300%, although elongations between 20% and 50% are sufficient in many applications.

[0198] Furthermore, it is possible that the films and / or electrical functional elements formed or preformed by means of the above-mentioned forming processes are pre-injected and / or back-injected in a subsequent injection molding process.

[0199] Furthermore, it is also possible for the film and / or the electrical functional element to be formed and / or deformed using an injection molding process. Advantageously, the film and / or the electrical functional element is introduced into the injection mold in a flat state via a roll, sheet, or individual label and deformed using the injection molding process, in particular whereby the shaping takes place by closing the mold and also by injecting the molding compound. In particular, the injection pressure depends on the component geometry and / or the component size. For example, it is possible for the injection pressure to be 500 bar and the injection temperature to be between 180 °C and 380 °C, whereby the injection pressure and injection temperature depend on the injection molding material.Furthermore, it is also expedient that the film and / or the electrical functional element introduced into the injection molding tool are heated before the closing process of the injection molding tool by heating the film and / or the electrical functional element, for example at temperatures between 30 °C and 300 °C, preferably between 80 °C and 150 °C. It is also possible for the film and / or the electrical functional element to be fitted or fixed into the cavity by means of a clamping frame and / or vacuum and / or overpressure.

[0200] It is also advantageous to reshape the film and / or the electrical functional element by "covering" the film and / or the electrical functional element over an already three-dimensionally preformed component. Advantageously, the "covering" of the film and / or the electrical functional element is carried out by controlling a vacuum suction of the film and / or the electrical functional element onto the already three-dimensionally preformed component while simultaneously applying overpressure in a single process. Preferably, the already three-dimensionally preformed component to be covered is preheated. It is expedient if the overpressure is between 1 bar and 50 bar, preferably between 3 bar and 15 bar, and / or the temperature is between 30°C and 300°C, preferably between 100°C and 180°C.

[0201] Preferably, the film and / or the electrical functional element has an extensibility of greater than 20%. Such high extensibility cannot be achieved, for example, by means of the above-mentioned forming and / or deformation processes with conventional functional films, in particular since the carrier film is made of, for example, PET is not deformable enough and / or the conductive structures break after even slight deformation, in particular at elongations greater than 20%. Here, it has been shown that the elongation is improved by the film according to the invention. Thus, the multi-layer structure of the film according to the invention, in particular by the at least one electrically conductive layer embedded between several lacquer layers according to a sandwich system, as described above, means that the mechanical elongation and / or deformation can be specifically influenced by, for example, adjusting the layer thicknesses and / or the lacquer formulations to make certain areas of the film more or less flexible. Thus, the desired elongation of greater than 20% is preferably achieved here.

[0202] Even with the above-mentioned three-dimensional deformations, it is advantageous if the electrical functional structure of the film and / or the electrical functional element can be electrically, in particular galvanically, contacted from the outside, for which the electrical contacts must be accessible for contacting. Alternatively, inductive and / or capacitive coupling, in particular coupling via an antenna, can be implemented. As explained above, the film according to the invention enables robust and secure contacting of the electrical functional structure.

[0203] Furthermore, it is possible for the adhesion-promoting layer to consist of a material whose optical appearance changes from cloudy to highly transparent and / or clear during and / or after step b). Thus, it is possible for the adhesion-promoting layer to be melted due to applied heat during application of the film to the target substrate and / or for the adhesion-promoting layer to be leveled by pressure, so that the surface roughness of the adhesion-promoting layer present in the unapplied state of the film is leveled during and / or after application. This changes the optical appearance of the adhesion-promoting layer from cloudy to highly transparent and / or clear.

[0204] After application of the film to a target substrate, the film forms an electrical functional element with the target substrate. Advantageously, after application of the film to the target substrate, the adhesion-promoting layer of the film is highly transparent. In particular, the adhesion-promoting layer of the film has a light transmission in the wavelength range between 380 nm and 780 nm of more than 85%, preferably more than 90%, and / or the adhesion-promoting layer of the film is a clear adhesion-promoting layer. In particular, light in the wavelength range between 380 nm and 780 nm is deflected by the adhesion-promoting layer of the film by less than 8%, preferably by less than 4%, due to scattering.It is also possible for the film, at least in the one functional region of the at least one electrically conductive layer, to have a light transmission in the wavelength range between 380 nm and 780 nm of more than 75%, preferably more than 80%, more preferably more than 85%, and even more preferably more than 90%. This can, for example, achieve a brilliant and true-to-original viewing of an image generated by a display to which the film is applied.

[0205] Furthermore, it is possible for the electrical functional element to be a functional element for information processing, in particular a mobile phone, such as a smartphone or a PDA, a tablet computer, an ATM, a ticket machine, a gaming machine, a gaming console, a control panel of a household appliance or a motor vehicle, or for example a touchscreen. It is also possible for the electrical functional element to be an input device, in particular a touch panel. However, it is also possible for the electrical functional element to be an intermediate product which is incorporated into or in a final product in further processing steps. For example, the film can be applied to a glass layer, and the electrical functional element formed from the glass layer and the film can be incorporated into a ticket machine, for example.

[0206] In the following, embodiments of the invention are explained by way of example with the aid of the enclosed figures, which are not to scale. Fig. 1a to Fig. 1f show schematic sectional views of films Fig. 2a and Fig. 2b show schematic sectional views of films Fig. 3 shows schematically a sectional view of a film Fig. 4a to Fig. 4c show schematic sectional views of films Fig. 5a to Fig. 5c show schematic sectional views of films Fig. 6a to Fig. 6c show schematic sectional views of films Fig. 7 shows schematically a sectional view of a film Fig. 8 shows schematically a sectional view of a film Fig. 9 shows schematically a sectional view of a film Fig. 10 shows schematically a sectional view of a film Fig. 11a shows schematically conductor tracks in plan view Fig. 11b shows schematically an enlarged section of the Fig. 11a Fig. 12 shows a schematic plan view of conductor tracks. Fig. 13 shows a schematic sectional view of a film. Fig. 14 shows a schematic plan view of films. Fig. 15a and Fig. 15b show a schematic plan view of films. Fig. 16a and Fig. 16b show a schematic plan view of films. Fig. 17a and Fig. 17b show a schematic plan view of films. Fig. 18a and Fig. 18b show a schematic plan view of films. Fig. 19a and Fig. 19b show a schematic plan view of films. Fig. 20a and Fig. 20b show a schematic plan view of films. Fig. 21a and Fig. 21b show a schematic plan view of films.22b schematically show method steps for producing an electrical functional element Fig. 23a to Fig. 23d schematically show top views of a target substrate, films and an electrical functional element Fig. 24a to Fig. 24e schematically show method steps for producing a film Fig. 25a and Fig. 25b schematically show a method step for producing a film Fig. 26a to Fig. 26c schematically show method steps for forming a film and / or an electrical functional element.

[0207] Fig. 1a shows a film 1 with a carrier substrate 2, an electrically conductive layer 3 and an adhesion-promoting layer 4.

[0208] The carrier substrate 2 is preferably a layer of PET, PMMA, PC, ABS, PU, ​​glass, or fabric. It is also possible for the carrier substrate 2 to be formed from a hybrid material comprising plastic layers and layers of fabric, in particular fiber material, such as paper, cotton, or other natural or synthetic fibers. The carrier substrate 2 preferably has a layer thickness between 2 µm and 250 µm, preferably between 23 µm and 125 µm. Fig. 1a The carrier substrate 2 shown is a transparent layer of PET with a layer thickness of 75 µm.

[0209] Transparent refers to the property of matter to allow light from the wavelength range visible to the human eye, in particular from the wavelength range between 380 nm and 780 nm, to pass through.

[0210] The electrically conductive layer 3 is preferably a layer of metal, in particular silver (Ag), gold (Au), aluminum (Al), copper (Cu) or chromium (Cr). The electrically conductive layer 3 preferably has a layer thickness between 1 nm and 100 nm, more preferably between 2.5 nm and 75 nm, even more preferably between 5 nm and 50 nm. It is also possible for the layer thickness of the electrically conductive layer 3 to be between 100 nm and 5 µm. The electrically conductive layer 3 can further be formed from an electrically conductive paste comprising silver (Ag), gold (Au), copper (Cu) and / or carbon. In the Fig. 1a The electrically conductive layer 3 shown is a layer of Ag with a layer thickness of 50 nm.

[0211] The electrically conductive layer 3 is formed such that the electrically conductive layer 3 has a plurality of conductor tracks which have a width 26 between 0.2 µm and 20 µm, preferably between 4 µm and 15 µm, and a distance 27 greater than 10 µm, preferably greater than 20 µm, from one another, so that the conductor tracks are below the resolution of the human eye. Conductor tracks are preferably understood here to mean structured electrically conductive layers and conductive regions of the at least one electrically conductive layer 3. The conductor tracks are applied in such a way that sufficient transparency for the human eye is maintained, i.e., the conductor tracks are designed in such a way that they are not perceived by a human observer, since the conductor tracks are below the resolution of the human eye.Despite the narrow conductor tracks used, sufficient electrical conductivity is achieved, which is particularly comparable to layers of indium tin oxide (ITO). Preferably, the coverage of the carrier substrate 2 with the at least one electrically conductive layer 3, in particular the conductor tracks, is less than 30%, preferably less than 20%, more preferably less than 10%, even more preferably less than 5%. Fig. 1a the width 26 of the conductor tracks formed by the electrically conductive layer 3 is 5 µm and the distance 27 of the conductor tracks formed by the electrically conductive layer 3 is 15 µm.

[0212] The electrically conductive layer 3 forms an electrical functional structure in the functional region 21, which forms a touch sensor field, in particular a capacitive sensor field. Furthermore, it is also possible for the electrical functional structure to form a resistive or inductive sensor field. The touch sensor field provides a touch field functionality. A touch sensor field is understood here to be a touch-sensitive sensor that enables the control of an electrical functional element, such as a smartphone, a games console, or a ticket machine. A touch sensor field is also understood to be a multi-touch sensor field, which can process several simultaneous touches, for example for enlarging and rotating images displayed on a display (not shown in detail here), which is arranged in particular below the touch sensor field.

[0213] The electrically conductive layer 3 further comprises a contacting region 20. The contacting region 20 forms a contacting structure for electrically contacting the functional structure. The contacting structure in the functional region 20 is, for example, an electrical connection in the form of a plug. Furthermore, it is possible for the contacting structure to comprise so-called pins, contacts, and / or studs. The contacting region 20 in Fig. 1a has an area of ​​0.3 mm x 2.0 mm. It is also possible for the electrically conductive layer 3 to form one or more separate contacting regions 20. Separated here means that the contacting regions are spaced apart from one another and thus also electrically insulated from one another, in particular that the contacting regions are spaced apart from one another by at least 0.1 mm, preferably at least 0.2 mm, more preferably at least 0.5 mm.

[0214] The adhesion-promoting layer 4 is preferably a layer of polymers and / or copolymers, in particular comprising PMMA, polyester, PU or PVC, with a layer thickness between 0.1 µm and 50 µm, preferably between 0.25 µm and 25 µm, more preferably between 0.5 µm and 7 µm. Fig. 1a The adhesion-promoting layer 4 shown is a layer of PVC copolymers with a layer thickness of 4 µm.

[0215] As in Fig. 1a As shown, the electrically conductive layer 3 is arranged between the carrier substrate 2 and the adhesion-promoting layer 4. The adhesion-promoting layer 4 is thus arranged on the side of the at least one electrically conductive layer 3 facing away from the carrier substrate 2. The film 1 has a top side 40 and a bottom side 41, with the adhesion-promoting layer 4 being arranged on the top side 40. As shown in Fig. 1a As shown, the adhesion-promoting layer 4 is arranged on the surface of the film 1.

[0216] The adhesion-promoting layer 4 is arranged in the region 22. The region 22 covers the functional structure formed by the electrically conductive layer 3 in the functional region 21 in Fig. 1a Completely. The adhesion-promoting layer 4 is not arranged in the region 23. The region 23 encompasses the contacting region 20 of the electrically conductive layer 3, so that the adhesion-promoting layer 4 does not fully cover the contacting region 20. When the film 1 is applied to a target substrate, the region 23 does not adhere to the target substrate, and therefore, in particular, the contacting region 20 is accessible after the film 1 has been applied to the target substrate, and the electrical functional structure can be reliably contacted.

[0217] However, it is also possible for the adhesion-promoting layer 4 not to completely cover the functional area 21. For example, the adhesion-promoting layer 4 can cover the functional area 21 by at least 30%, preferably by at least 50%, more preferably by at least 70%.

[0218] The adhesion-promoting layer 4 preferably consists of a material that is highly transparent after the film 1 has been applied to a target substrate. The term "highly transparent" describes the property of a material that barely attenuates light from the wavelength range visible to the human eye, in particular from the wavelength range between 380 nm and 780 nm, and allows it to pass through essentially unhindered. A highly transparent layer therefore exhibits essentially no discernible light absorption for a human observer, so that the light intensity is barely discernibly reduced when the light passes through the layer.

[0219] Thus, the adhesion-promoting layer 4 preferably consists of a material which, after application to the target substrate, has a transmission of light in the wavelength range between 380 nm and 780 nm of more than 85%, preferably more than 90%.

[0220] Preferably, the adhesion-promoting layer 4 consists of a material which is clear after application of the film 1 to a target substrate, so that light in the wavelength range between 380 nm and 780 nm is deflected by less than 8%, preferably by less than 4%, by scattering from the adhesion-promoting layer 4 after application of the film 1 to the target substrate.

[0221] As previously explained, the adhesion-promoting layer 4, in a state not yet applied to the target substrate, can exhibit light-scattering properties, in particular due to surface roughness of the adhesion-promoting layer 4, which can arise, for example, from traces of the process steps for applying the adhesion-promoting layer 4. The adhesion-promoting layer 4 becomes highly transparent and / or clear, in particular, when the film 1 is applied to the target substrate and the adhesion-promoting layer 4 is melted and / or leveled, for example, by means of heat and / or pressure applied during hot lamination, so that the surface roughness of the adhesion-promoting layer 4 no longer has a disruptive appearance. This means that the adhesion-promoting layer 4 becomes highly transparent and / or clear due to physical and / or chemical changes to the adhesion-promoting layer 4 during or after the application of the film 1 to the target substrate.

[0222] The partially applied adhesion-promoting layer 4 is preferably a layer of a hot-melt adhesive or a radiation-curable adhesive, in particular an adhesive curable by electromagnetic radiation and / or electron beams. Radiation-curable adhesives are cured, for example, by UV light and / or IR light (UV = ultraviolet; IR = infrared).

[0223] Fig. 1b shows a film 1 comprising a carrier substrate 2, an electrically conductive layer 3, a protective lacquer layer 6, a contact reinforcement layer 7 and an adhesion-promoting layer 4.

[0224] The protective lacquer layer 6 is preferably a layer of PMMA, polyester, PU or PVC with a layer thickness between 0.1 µm and 50 µm, preferably between 0.25 µm and 25 µm, more preferably between 0.5 µm and 15 µm. Fig. 1b The protective lacquer layer 6 shown is a transparent layer of PAC with a layer thickness of 5 µm.

[0225] The protective lacquer layer 6 covers the electrically conductive layer 3, but not the contacting area 20. Thus, the protective lacquer layer 6 covers the functional area 21 formed by the electrically conductive layer 3, but not the contacting area 20. The protective lacquer layer 6 is, as in Fig. 1b shown, arranged on the side of the electrically conductive layer 3 facing away from the carrier substrate 2. The protective lacquer layer 6 is thus arranged between the electrically conductive layer 3 and the adhesion-promoting layer 4.

[0226] The contact reinforcement layer 7 is preferably a layer of an electrically conductive paste, in particular a carbon paste, comprising silver (Ag), gold (Au), aluminum (Al), copper (Cu), chromium (Cr), and / or other conductive metals. Furthermore, the electrically conductive paste, in particular a carbon paste, may comprise binders, in particular rosin and / or phenolic resins, polymers, and copolymers.

[0227] Binders are substances that bind solids, especially those with a fine degree of particle size, together or to a substrate. Thus, binders can be added in liquid form to the solids to be bound.

[0228] Binders for the electrically conductive paste, especially carbon paste, are natural resins, preferably rosin, phenolic resins, polymers and copolymers consisting of PVC, PMMA, PU, ​​polyester, isocyanate (NCO)-crosslinked binders, for example, MF, MPF, melamine-polyester, UMF. Less preferred are binders for the electrically conductive paste comprising poly(organo)siloxanes and their copolymers and / or radiation-curing binders.

[0229] For example, paints and pastes can be solvent-based or water-based in the form of an emulsion, dispersion or suspension.

[0230] The contact reinforcement layer 7 preferably has a layer thickness between 0.1 µm and 100 µm, preferably between 0.25 µm and 25 µm, more preferably between 0.5 µm and 10 µm.

[0231] At the Fig. 1b The contact reinforcement layer 7 shown is a layer of a carbon paste with a layer thickness of 4.5 µm.

[0232] The contact reinforcement layer 7 is applied in the contacting region 20 of the electrically conductive layer 3. The electrically conductive layer 3 has the contact reinforcement layer 7 in the contacting region 20. As in Fig. 1b As shown, the contact reinforcement layer 7 is applied over the entire surface of the contacting region. However, it is also possible for the contact reinforcement layer 7 to be applied only in certain areas of the contacting region 20. The contact reinforcement layer 7 protects the contacting region 20 or the contact structure formed in the contacting region 20 from mechanical, physical, and / or chemical environmental influences.

[0233] The adhesion-promoting layer 4 is, as in Fig. 1b shown, present in the region 22 and not present in the region 23. The adhesion-promoting layer 4, when viewed perpendicular to a plane spanned by the carrier substrate 2, is therefore not present in the region 24, which is encompassed by the region 23. The region 24 borders on the contacting region 20 and does not have the adhesion-promoting layer 4. The adhesion-promoting layer 4 is only applied in the region 22 and does not cover the region 24 bordering the contacting region 20. When the film 1 is applied to a target substrate, the film 1 therefore only adheres to the target substrate in the region 22. In the region 23, which comprises the regions 20 and 24, the film 1 does not adhere to the target substrate, so that the contacting region 20 is accessible. Furthermore, the area 23 can be raised, wherein the area 24 adjacent to the contacting area 20, for example, performs a hinge function for lifting the area 23.

[0234] The region 24 preferably has a width of at least 0.2 mm, preferably of at least 0.5 mm, more preferably of at least 1 mm, even more preferably of at least 2 mm. Fig. 1b The region 24 shown has a width of 1 mm. The width of the region 24 can be selected depending on the requirements of the target substrate to which the film 1 is to be applied, or depending on the further processing step after application of the film 1 to the target substrate. Width here refers to the distance between the interface 42, which is formed by the contacting region 20 and the region 24 adjacent to the contacting region 20, and the interface 43, which is formed by the adhesion-promoting layer 4 and the region 24 adjacent to the contacting region 20.

[0235] Regarding the design of the further layers in Fig. 1b reference is made here to the above statements.

[0236] Fig. 1c shows a film 1 with a carrier substrate 2, an electrically conductive layer 3, an adhesion-promoting layer 4, a release layer 5, a protective lacquer layer 6, and a contact-reinforcing layer 7. The release layer 5 is preferably a layer made of waxes, polyethylene (PE), polypropylene (PP), cellulose derivatives, or poly(organo)siloxanes. The aforementioned waxes can be natural waxes, synthetic waxes, or combinations thereof. The aforementioned waxes include, for example, carnauba waxes. The aforementioned cellulose derivatives include, for example, cellulose acetate (CA), cellulose nitrate (CN), cellulose acetate butyrate (CAB), or mixtures thereof. The aforementioned poly(organo)siloxanes include, for example, silicone binders, polysiloxane binders, or mixtures thereof. The release layer 5 preferably has a layer thickness between 0.1 µm and 10 µm, preferably between 0.01 µm and 5 µm. Fig. 1c The release layer 5 shown is a layer of a PE wax dispersion with a layer thickness of less than 1 µm.

[0237] The release layer 5 covers, as in Fig. 1c shown, the area 24 adjacent to the contacting area 20 is covered over the entire surface. The contacting area 20 is only partially covered by the release layer 5. However, it is also possible for the release layer to cover the contacting area 20 over its entire surface. It is also possible for the release layer to be applied over the entire surface or at least partially in the contacting area 20, but not in the area 24 adjacent to the contacting area 20.

[0238] The release layer 5 prevents the areas to which the release layer 5 is applied from adhering to a target substrate to which the film 1 is applied. Fig. 1c The film 1 shown in the region 22 after application to a target substrate adheres to the target substrate, but not in the region 23, which includes the regions 20 and 24. The release layer 5 can thus ensure that the regions having the release layer 5 do not adhere to the target substrate, for example, by hot lamination to a target substrate.

[0239] Regarding the design of the further layers in Fig. 1c reference is made here to the above statements.

[0240] Advantageously, after application to a target substrate, the film 1 has in the functional area formed by the electrically conductive layer 3 at least a transmission of light in the wavelength range between 380 nm and 780 nm of more than 75%, preferably more than 80%, more preferably more than 85%, even more preferably more than 90%.

[0241] The transmittance describes the permeability of film 1 for light in the wavelength range between 380 nm and 780 nm. Light incident on film 1 is partially reflected at the interface between air and film 1 and at the interfaces between the layers of film 1. Furthermore, the light incident on film 1 is partially absorbed as it passes through film 1. The remaining portion of the light is transmitted through film 1 and exits again on the opposite side of film 1. To determine the transmittance τ, the quotient of the light intensity behind film I and the light intensity in front of film I 0 is calculated. The transmittance τ is a measure of the "transmitted" intensity and takes values ​​between 0 and 1. The transmittance typically depends on the wavelength of the incident light.

[0242] As previously explained, the adhesion-promoting layer 4 may have a cloudy visual impression prior to application of the film 1 to a target substrate, which is caused in particular by surface roughness of the adhesion-promoting layer 4. After application of the film 1 to the target substrate, these surface roughnesses are leveled, for example, by heat applied during the application process, which melts the adhesion-promoting layer 4, and / or by pressure exerted, which levels the adhesion-promoting layer by pressing it against the target substrate. As a result, the adhesion-promoting layer becomes highly transparent and / or clear, particularly after application to the target substrate, so that the cloudy visual impression disappears and high transmission values ​​of the applied film 1 can be achieved. Therefore, the transmission of the film 1 is preferably measured after application to a target substrate, as explained below.

[0243] For example, if film 1 is applied to a PMMA target substrate and the total transmittance of the electrical functional element formed from the target substrate and film 1 is subsequently determined, the total transmittance is 84.6%. This total transmittance is obtained from both a measurement taken from the side of the PMMA target substrate 10 and from the side of the carrier substrate 2 of film 1. The PMMA target substrate exhibits a transmittance of 93.6%. The Byk Gardener Haze-Gard Plus measuring device from BYK-Gardner GmbH, Geretsried, Germany, was used to measure the total transmittance and the transmittance of the PMMA target substrate.

[0244] Fig. 1d shows a film 1 with a carrier substrate 2, an electrically conductive layer 3, an adhesion-promoting layer 4, a release layer 5, a protective lacquer layer 6 and a contact-reinforcing layer 7.

[0245] The Fig. 1d Slide 1 shown corresponds to the one in Fig. 1c shown film with the difference that the protective lacquer layer 6 in Fig. 1d with a greater layer thickness. Fig. 1d The protective lacquer layer 6 shown has a layer thickness of 10 µm.

[0246] Fig. 1e shows a film 1 with a carrier substrate 2, a first electrically conductive layer 3a, a protective lacquer layer 6, a second electrically conductive layer 3b, an adhesion-promoting layer 4, a release layer 5 and a contact-reinforcing layer 7.

[0247] The first electrically conductive layer 3a is shaped such that the first electrically conductive layer 3a has a plurality of conductor tracks that run in the y-direction and are strip-shaped. The second electrically conductive layer 3b is shaped such that the second electrically conductive layer 3b has a plurality of conductor tracks that run in the x-direction and are also strip-shaped. The conductor tracks of the first electrically conductive layer 3a can be designed as sensor conductor tracks, and the conductor tracks of the second electrically conductive layer can be designed as driver conductor tracks, wherein the first electrically conductive layer 3a is electrically insulated from the second electrically conductive layer 3b by the protective lacquer layer 6. Furthermore, it is possible for the conductor tracks of the first and second electrically conductive layers to be diamond-shaped.Furthermore, it is possible for the conductor tracks of the first electrically conductive layer 3a to form the y-sensors of a touch sensor, and for the conductor tracks of the second electrically conductive layer 3b to form the x-sensors of the touch sensor. It is also possible for the conductor tracks of the first electrically conductive layer and the conductor tracks of the second electrically conductive layer to have different shapes, in particular for the conductor tracks to have different widths and / or different spacings. Regarding the further design of the conductor tracks, reference is made to the above explanations.

[0248] As in Fig. 1e As shown, the film 1 has the adhesion-promoting layer 4 in the region 22 and not in the region 23. The release layer 5 is further applied to the contact-reinforcing layer 7 in the contacting region 20, wherein the release layer completely covers the contacting region 20. After application to a target substrate, the film 1 adheres to the target substrate in the region 22, and in the region 23, which encompasses the region 20, the film 1 does not adhere to the target substrate, so that the contacting region 20 is accessible.

[0249] Regarding the design of the further layers in Fig. 1e reference is made here to the above statements.

[0250] Fig. 1f shows a film 1 with a carrier substrate 2, a first electrically conductive layer 3a, a dielectric layer 8, a second electrically conductive layer 3b, a protective lacquer layer 6, an adhesion-promoting layer 4, a release layer 5 and a contact-reinforcing layer 7.

[0251] Regarding the design of layers 2, 3a, 3b, 4, 5, 6 and 7 in Fig. 1f reference is made here to the above statements. As in Fig. 1f As shown, a dielectric layer 8 is arranged between the first electrically conductive layer 3a and the second electrically conductive layer 3b. The dielectric layer is preferably a layer of PE, PTFE or ceramic with a layer thickness between 0.1 µm and 100 µm, preferably between 0.25 µm and 25 µm, more preferably between 0.5 µm and 10 µm. Fig. 1f The dielectric layer shown is a PE layer with a layer thickness of 6 µm. It is also possible that layer 8 is a semiconducting or insulating layer.

[0252] As in Fig. 1f As shown, the film 1 has the adhesion-promoting layer 4 in the area 22 and not in the area 23. The release layer 5 is, as in Fig. 1f shown, present both in the contacting region 20 and in the region 24 adjacent to the contacting region 20. The release layer is applied over the entire surface in regions 20 and 24. After application to a target substrate, the film 1 adheres to the target substrate in region 22, and in region 23, which comprises regions 20 and 24, the film 1 does not adhere to the target substrate, so that the contacting region 20 is accessible. Furthermore, the film 1 can be lifted in region 23 after application to the target substrate, so that secure and robust contact is enabled. The region 24 can serve as a movable hinge to lift the contacting region 20.

[0253] Fig. 2a und Fig. 2b show further embodiments of the film 1 according to the invention, which comprise a carrier substrate 2, an electrically conductive layer 3 and an adhesion-promoting layer 4.

[0254] In the Fig. 2a shown electrically conductive layer 3, surface relief structures are molded. The electrically conductive layer 3 in Fig. 2a is, for example, a metal layer made of aluminum, which is initially applied in regions over the entire surface of the carrier substrate 2. Subsequently, the surface relief structures of the metal layer 3 can be created by etching the metal using acid, by laser structuring the surface, or by mechanical surface treatment. The aforementioned laser structuring of the surface is carried out, for example, by removal, in particular ablation, of the metal on the surface of the metal layer using a solid-state laser, such as an Nd:YAG laser. The aforementioned mechanical surface treatment preferably involves rubbing, sanding, brushing, or similar mechanical roughening processes. Such a surface treatment of the metal layer can be carried out over the entire surface of the metal layer 3 or only in certain regions. Fig. 2a The metal layer 3 has surface relief structures throughout the entire functional area 21, but not in the contact area 20. After the surface treatment, the metal layer 3 is structured to create the conductor tracks. The metal layer 3 can be structured, for example, by demetallization processes such as etching or washing, i.e., removed in certain areas to create the conductor tracks.

[0255] As in Fig. 2a As shown, the adhesion-promoting layer 4 is present in the region 22 and not present in the region 23, so that the film 1, after application to a target substrate, adheres to the target substrate in the region 22 and does not adhere to the target substrate in the region 23, which includes the contacting region 20. The contacting region 20 is thus accessible after application to the target substrate.

[0256] Regarding the further design of layers 3 and 4 or the design of layer 2 in Fig. 2a reference is made here to the above statements.

[0257] The Fig. 2b Slide 1 shown corresponds to the one in Fig. 2a shown film 1 with the difference that the electrically conductive layer 3 does not have any surface relief structures, but rather that a darkening layer 9 is applied to the electrically conductive layer 3. The darkening layer 9 is preferably a layer of a dark color which absorbs light incident on the darkening layer 9. The darkening layer 9 can be applied using conventional coating methods such as printing, doctor blade coating or spin coating. The electrically conductive layer 3 and the carrier substrate 2 can also have different wettability, for example, wherein the wettability of a color varnish providing the darkening layer 9 is selected such that it adheres well exclusively to the conductor tracks formed by the electrically conductive layer 3. The darkening layer 9 can also be applied selectively to the conductor tracks using a thermal transfer method.Thus, the conductor tracks can be selectively heated by a lamp, with molten coloring material being preferentially deposited on the heated conductor tracks. However, it is also possible for layer 9 to be a layer with light-scattering properties. For this purpose, the layer with light-scattering properties preferably has a surface relief structure, in particular a matte structure with stochastically selected relief parameters. However, it is also possible for layer 9 to be a layer having light-absorbing surface relief structures, such as moth-eye structures.

[0258] Fig. 3 shows a film 1 with a carrier substrate 2, an electrically conductive layer 3, an intermediate adhesive layer 11, the decorative layers 12a and 12b, an adhesion-promoting layer 4, a release layer 5 and a contact-reinforcing layer 7.

[0259] The intermediate adhesive layer 11 is, as in Fig. 3 shown, arranged on the side of the electrically conductive layer facing away from the carrier substrate 2. Furthermore, the intermediate adhesive layer 11 covers the functional region 21 formed by the electrically conductive layer 3, but not the contacting region 20. Furthermore, the intermediate adhesive layer 11 is arranged between the electrically conductive layer and the first decorative layer 12a.

[0260] The intermediate adhesive layer 11 is preferably a primer layer and / or an adhesive layer made of a hot-melt adhesive, a cold-melt adhesive, or a radiation-curable adhesive, in particular an adhesive curable by means of electromagnetic radiation and / or electron beams. It is also possible for the intermediate adhesive layer 11 to comprise PMMA, polyester, PU, ​​or PVC. The intermediate adhesive layer 11 is preferably applied by means of gravure printing, screen printing, letterpress printing, or casting techniques in a layer thickness between 0.1 µm and 50 µm, preferably between 0.25 µm and 25 µm, more preferably between 0.5 µm and 7 µm. Fig. 3 The intermediate adhesive layer 11 shown is a hot-melt adhesive layer with a layer thickness of 5 µm.

[0261] As in Fig. 3 The decorative layers 12a and 12b are shown arranged in the same region 22 as the adhesion-promoting layer 4, so that the decorative layers 12a and 12b, when viewed perpendicular to a plane spanned by the carrier substrate 2, are arranged congruently with the adhesion-promoting layer 4 and / or the intermediate adhesive layer 11. This ensures that the contacting area is accessible for secure and robust contacting of the electrical functional structure despite the additional decorative layers 12a and 12b.

[0262] At the Fig. 3 The decorative layer 12a shown is preferably a replication lacquer layer. The replication lacquer layer consists, for example, of a thermoplastic lacquer into which a surface relief structure is molded, at least in regions, by means of heat and pressure through the action of an embossing tool. Furthermore, it is also possible for the replication lacquer layer to be formed from a UV-crosslinkable lacquer and for the surface relief structure to be molded into the replication lacquer layer by means of UV replication. In this case, the surface relief structure is molded by the action of an embossing tool on the uncured replication lacquer layer and the replication lacquer layer is cured immediately during or after the molding by irradiation with UV light. Furthermore, it is advantageous for the replication lacquer layer to have a layer thickness between 0.2 µm and 4 µm, preferably 0.3 µm and 2 µm, more preferably 0.4 µm and 1.5 µm. In the case of the Fig. 3 The decorative layer 12a shown is a replication lacquer layer made of a UV-crosslinkable lacquer with a layer thickness of 1.25 µm.

[0263] At the Fig. 3 The decorative layer 12b shown is preferably a reflective layer. The reflective layer is preferably a metal layer made of chromium, aluminum, gold, copper, silver, or an alloy of such metals, which is vacuum-deposited to a layer thickness of 0.01 µm to 0.15 µm. Furthermore, it is also possible for the reflective layer to be formed by a transparent reflective layer, preferably a thin or finely structured metallic layer or a dielectric HRI or LRI layer. (engl. High refraction index (HRI), low refraction index (LRI). Such a dielectric reflective layer consists, for example, of a vapor-deposited layer of a metal oxide, metal sulfide, e.g., titanium oxide, etc., with a thickness of 10 nm to 150 nm. Furthermore, it is also possible for the reflective layer to be applied only in certain areas. Thus, it is possible for partial metallization to be present, forming, for example, a metallic text or nanotext. Fig. 3 The decorative layer 12b shown is a metal layer made of copper with a layer thickness of 10 nm.

[0264] Regarding the design of the further layers in Fig. 3 reference is made here to the above statements.

[0265] Fig. 4a shows a film 1 with a carrier substrate 2, an electrically conductive layer 3, an intermediate adhesive layer 11, a decorative layer 12c, an adhesion-promoting layer 4 and a contact-reinforcing layer 7.

[0266] As in Fig. 4a As shown, the adhesion-promoting layer 4 is arranged on the side of the carrier substrate 2 facing away from the electrically conductive layer. Furthermore, the adhesion-promoting layer 4 is applied over the entire surface when viewed perpendicular to a plane spanned by the carrier substrate 2. However, it is also possible that the adhesion-promoting layer 4 is not arranged in the region 23a, which overlaps the contacting region 20 of the electrically conductive layer 3. Furthermore, the adhesion-promoting layer 4 comprises, as in Fig. 4a Layers 4a and 4b are shown. This makes it possible to optimize the adhesion of film 1 to a target substrate. Thus, layer 4a can be optimized for the material of the carrier substrate 2, and layer 4b can be optimized for the material of the target substrate to which film 1 is to be applied by means of the adhesion-promoting layer 4.

[0267] The intermediate adhesive layer 11 is, as in Fig. 4a shown, arranged on the side of the electrically conductive layer 3 facing away from the carrier substrate 2. Furthermore, the intermediate adhesive layer 11 covers the functional region 21 formed by the electrically conductive layer 3, but not the contacting region 20. Furthermore, the intermediate adhesive layer 11 is arranged between the electrically conductive layer and the first decorative layer 12c.

[0268] The decorative layer 12c is, as in Fig. 4a shown, are arranged in the same area as the intermediate adhesive layer 11, so that the decorative layer 12c, when viewed perpendicular to a plane spanned by the carrier substrate 2, is arranged congruently with the intermediate adhesive layer 11. This ensures, in particular, that the contacting area 20 can be contacted securely and robustly despite the additional decorative layer 12c.

[0269] The decorative layer 12c is preferably a transparent colored lacquer layer. The decorative layer 12c contains dyes and / or pigments that impart a color filter effect to the decorative layer 12c, for example.

[0270] The decorative layer 12c preferably forms a pattern. A pattern can be, for example, a graphically designed outline, a figurative representation, an image, a motif, a symbol, a logo, a portrait, an alphanumeric character, a text, and the like. It is also possible for the pattern to have differently colored pattern elements.

[0271] However, it is also possible for the decorative layer 12c to be a printed layer, in particular made of an opaque and / or colored ink. The printed layer can, for example, form a frame around the functional area 21 or be printed in a pattern, for example, in a linear pattern.

[0272] Regarding the design of the further layers in Fig. 4a reference is made here to the above statements.

[0273] Fig. 4b shows a film 1 with a carrier substrate 2, an electrically conductive layer 3, an intermediate adhesive layer 11, the decorative layers 12c and 12d, an adhesion-promoting layer 4 and a contact-reinforcing layer 7.

[0274] The decorative layer 12d is preferably a transparent carrier layer made of PET, PMMA, PC, ABS, PU, ​​glass, fabric, or a hybrid material comprising plastic layers and layers of fabric, in particular fiber material, such as paper, cotton, or other natural or synthetic fibers. The carrier layer preferably has a layer thickness between 2 µm and 250 µm, preferably between 23 µm and 125 µm. Fig. 4b The decorative layer 12d shown is a transparent layer of PET with a layer thickness of 25 µm. As shown in Fig. 4b The decorative layer 12d is also shown arranged congruently with the intermediate adhesive layer 11, so that the contacting area remains accessible and the electrical functional structure can be contacted safely and robustly.

[0275] Regarding the design of the further layers in Fig. 4b reference is made here to the above statements.

[0276] Fig. 4c shows a film 1 with a carrier substrate 2, an electrically conductive layer 3, an intermediate adhesive layer 11, the decorative layers 12c, 12d and 12e, an adhesion-promoting layer 4 and a contact-reinforcing layer 7.

[0277] The decorative layer 12e is preferably a transparent colored lacquer layer. The decorative layer 12e contains dyes and / or pigments, which impart a color filter effect to the decorative layer 12e, for example. If, for example, the decorative layer 12c is also formed as a transparent colored lacquer layer, as explained above, the interaction of the two decorative layers 12c and 12e creates a color filter effect, in particular a color mixing effect, for the viewer. However, it is also possible, for example, for the decorative layer 12c and the decorative layer 12e to be printed layers, each forming a pattern. The two decorative layers 12c and 12e can interact with each other in such a way that a moiré effect is created for the viewer, thus making a predetermined moiré pattern recognizable. The decorative layer 12d can serve, for example, as a transparent spacer layer. The decorative layer 12e is also, as in Fig. 4b shown, arranged congruently with the intermediate adhesive layer 11, so that the contacting area remains accessible.

[0278] Regarding the design of the further layers in Fig. 4c reference is made here to the above statements.

[0279] Fig. 5a shows a film 1 with a carrier substrate 2, an electrically conductive layer 3, an intermediate adhesive layer 11, the decorative layers 12c, 12d and 12f, an adhesion-promoting layer 4 and a contact-reinforcing layer 7.

[0280] The adhesion-promoting layer 4 can, as in Fig. 5a shown, be applied over the entire surface. However, it is also possible for the adhesion-promoting layer 4 to be absent in the region 23a. This further improves the accessibility of the contacting area, since the corresponding surface area 23a remains free on both sides, which can be electrically contacted in a particularly simple manner in subsequent processing steps, for example by means of a plug connection.

[0281] The decorative layer 12f is preferably an optically transparent lacquer layer that is partially printed. The decorative layer 12f creates a haptic and / or tactile effect due to the surface relief structures. The decorative layer 12f can therefore be perceived haptically and / or tactilely. Furthermore, it is also possible for the surface relief structures of the decorative layer 12f to create diffractive and / or refractive optical effects. It is also possible for the surface relief structures to be created by mechanical structuring or optical structuring, in particular by means of a laser, of the layer surface. Mechanical structuring can be replication using a correspondingly shaped embossing tool. Optical structuring can be laser ablation. Furthermore, photolithographic processes can also be used to create these structures.The structural depths of the surface relief structures for haptic and / or tactile perception are preferably between 1 µm and 2000 µm, more preferably between 50 µm and 2000 µm. Structural depths for diffractive or refractive effects are preferably between 0.1 µm and 20 µm, more preferably between 0.1 µm and 5 µm.

[0282] As in Fig. 5a As shown, the decorative layer 12f is arranged on the decorative layer 12d. Furthermore, the decorative layers 12c, 12d, and 12f are arranged on the same side of the carrier substrate 2.

[0283] Regarding the design of the further layers in Fig. 5a reference is made here to the above statements.

[0284] Fig. 5b shows a film 1 with a carrier substrate 2, an electrically conductive layer 3, an intermediate adhesive layer 11, the decorative layers 12c, 12d, 12e and 12f, an adhesion-promoting layer 4 and a contact-reinforcing layer 7.

[0285] Regarding the design of the layers in Fig. 5b reference is made here to the above statements.

[0286] Fig. 5c shows a film 1 with a carrier substrate 2, an electrically conductive layer 3, an intermediate adhesive layer 11, the decorative layers 12a, 12b and 12f, an adhesion-promoting layer 4, a release layer 5 and a contact-reinforcing layer 7.

[0287] As in Fig. 5c As shown, the decorative layer 12f is arranged on the side of the carrier substrate 2 facing away from the electrically conductive layer 3. The decorative layers 12a and 12b, however, are arranged on the side of the carrier substrate 2 facing the electrically conductive layer 3 and on the side of the electrically conductive layer 3 facing away from the carrier substrate 2, respectively.

[0288] Regarding the design of the layers in Fig. 5c reference is made here to the above statements.

[0289] Fig. 6a shows a film 1 with a carrier substrate 2, an electrically conductive layer 3, an intermediate adhesive layer 11, the decorative layers 12d, 12g, 12h and 12i, an adhesion-promoting layer 4 and a contact-reinforcing layer 7.

[0290] The decorative layers 12d, 12g, 12h and 12i are, as in Fig. 6a shown, are arranged in the same area as the intermediate adhesive layer 11, the decorative layers 12d, 12g, 12h and 12i are arranged congruently with the intermediate adhesive layer 11 when viewed perpendicular to a plane spanned by the carrier substrate 2. This ensures, in particular, that the contacting area 20 can be contacted securely and robustly despite the additional decorative layers 12d, 12g, 12h and 12i.

[0291] The decorative layers 12g, 12h and 12i form, for example, a thin-film layer system. The decorative layer 12g is a semi-transparent reflection layer, preferably a very thin and thus semi-transparent metal layer, for example a layer of chromium with a layer thickness of 5 nm. The decorative layer 12h is a spacer layer, preferably made of a transparent dielectric, for example MgF 2 , SiO 2 or a polymer. The layer thickness of the spacer layer is preferably selected such that it fulfills the λ / 2 or λ / 4 condition for λ in the range of the wavelength of visible light for a defined viewing angle, i.e.that the optical thickness of the decorative layer 12h is in the range of half or quarter wavelengths of light, and thus, upon interference of the light reflected back from the interface between the decorative layer 12g and the spacer layer 12h on the one hand, and the interface between the spacer layer 12h and the decorative layer 12i on the other hand, a viewing angle-dependent color shift effect is generated in the range of light visible to the human eye. The decorative layer 12i is a metallic reflective layer, preferably an opaque metal layer, for example, an aluminum layer with a layer thickness of 30 nm.

[0292] Regarding the design of the further layers in Fig. 6a reference is made here to the above statements.

[0293] Fig. 6b und Fig. 6c each show a film 1 with a carrier substrate 2, an electrically conductive layer 3, an intermediate adhesive layer 11, the decorative layers 12d, 12j, and 12h, an adhesion-promoting layer 4 and a contact-reinforcing layer 7.

[0294] The decorative layer 12h is a transparent layer that serves as a spacer layer. The spacer layer 12h creates an optical depth effect. As shown in the Fig. 6b und Fig. 6c As shown, the decorative layer 12h can be arranged behind and / or in front of the decorative layer 12j in the viewing direction. However, it is also possible for the decorative layer 12h to be arranged, for example, between two decorative layers. The optically transparent layer 12h has a layer thickness which is a multiple of the layer thickness of the decorative layer 12j. However, it is also possible for the layer thickness of the decorative layer 12h to be substantially equal to the layer thickness of the decorative layer 12j. Preferably, the layer thickness of the optically transparent layers 12h is between 0.5 µm and 500 µm, more preferably between 10 µm and 100 µm. The optically transparent layer 12h consists, for example, of optically transparent lacquers and / or optically transparent films, in particular of PET, PMMA or PC.

[0295] The decorative layer 12j may, for example, be a metallic layer, for example a layer of aluminum with a layer thickness of 20 nm. Advantageously, the decorative layer 12j is implemented in regions and forms a pattern.

[0296] Regarding the design of the further layers in Fig. 6b und Fig. 6c reference is made here to the above statements.

[0297] Fig. 7 shows a film 1 with a carrier substrate 2, a release layer 13, a protective lacquer layer 6, an electrically conductive layer 3, an intermediate adhesive layer 11, a release layer 5, the decorative layers 12a and 12b, an adhesion-promoting layer 4 and a contact-reinforcing layer 7.

[0298] The separating layer 13 is preferably a wax layer and / or a polymer layer made of, for example, acrylates and / or melamine-formaldehyde resin-crosslinked lacquers. The separating layer 13 preferably has a layer thickness of less than 1 µm. Fig. 7 The separating layer 13 shown is a wax layer with a layer thickness of 0.5 µm.

[0299] Thus, it is possible for the film 1 to be a transfer film comprising a carrier layer, in particular the carrier substrate 2, and a transfer layer 70 detachable from the carrier layer, in particular the carrier substrate 2. Advantageously, the separating layer 13 is arranged between the carrier layer, in particular the carrier substrate 2, and the transfer layer 70, which allows the transfer layer 70 to be detachable from the carrier layer, in particular the carrier substrate 2. This makes it possible to apply only the transfer layer 70 to a target substrate, in particular by hot stamping. In Fig. 7 The transfer layer 70 is formed from the release layer 13, the protective lacquer layer 6, the electrically conductive layer 3, the intermediate adhesive layer 11, the release layer 5, the decorative layers 12a and 12b, the adhesion-promoting layer 4, and the contact-reinforcing layer 7. The release layer 13 can be removed after application of the transfer layer of the film 1 to a target substrate.

[0300] Furthermore, it is possible for the separating layer 13 to be a single-layer or multi-layer separating layer. Preferably, the separating layer 13 is arranged between the carrier substrate 2 and the protective lacquer layer 6. This makes it possible for the protective lacquer layer 6 to form the outermost layer after the film 1 has been applied to a target substrate and after the carrier substrate 2 and the separating layer 13 have been removed, and to protect the electrically conductive layer 3 from environmental influences. Furthermore, this makes it possible for the carrier substrate 2 to be removed after the film 1 has been applied to the target substrate. This allows even better deformability and / or extensibility of the applied film to be achieved, since the comparatively thick and less deformable and / or extensible carrier substrate 2 has been removed. The protective lacquer layer 6 performs the function of protecting the film 1.

[0301] Regarding the design of the further layers in Fig. 7 reference is made here to the above statements.

[0302] Fig. 8 shows a film 1 with a carrier substrate 2, a release layer 13, a protective lacquer layer 6, a primer lacquer layer 14, an electrically conductive layer 3, an intermediate adhesive layer 11, a release layer 5, the decorative layers 12a and 12b, an adhesion-promoting layer 4 and a contact-reinforcing layer 7.

[0303] Advantageously, the primer layer 14 is a primer layer which can be vapor-deposited for metallization and which is arranged in particular between the protective lacquer layer 6 and the electrically conductive layer 3.

[0304] The primer layer 14 is preferably a layer of polymers and / or copolymers, in particular comprising polymethyl (meth)acrylate (PMMA), polyester, polyurethane (PU), or polyvinyl chloride (PVC). Less preferably, the primer layer 14 comprises natural resins, preferably rosin, phenolic resins, isocyanate (NCO)-crosslinked binders, for example, melamine-formaldehyde condensation resins (MF), melamine-phenol-formaldehyde resins (MPF), melamine-polyesters, melamine-urea-formaldehyde resins (UMF), poly(organo)siloxanes, or radiation-curing binders.

[0305] Furthermore, the primer coat layer 14 preferably has a layer thickness between 0.1 µm and 5 µm, more preferably between 0.1 µm and 2 µm.

[0306] At the Fig. 8 The primer layer 14 shown is a layer of PMMA with a layer thickness of 1.5 µm.

[0307] Advantageously, it can be provided that the adhesive force between the carrier substrate 2 and the protective lacquer layer 6 is 20% to 80%, preferably 30% to 70%, smaller than the adhesive force between the protective lacquer layer 6 and the primer lacquer layer 14 and / or the at least one electrically conductive layer 3 and / or the adhesion-promoting layer 4 due to the separating layer 13 arranged between the carrier substrate 2 and the protective lacquer layer 6.

[0308] It is thus possible that the adhesive force between the carrier substrate 2 and the protective lacquer layer 6, due to the separating layer 13 arranged between the carrier substrate 2 and the protective lacquer layer 6, is 20% to 80%, preferably 30% to 70%, lower than the adhesive force between the layers of the transfer layer, in particular selected from the group consisting of a protective lacquer layer, a primer lacquer layer, at least one electrically conductive layer, one or more decorative layers, an adhesion promoter layer, an intermediate adhesive layer, a dielectric layer, a darkening layer, and a contact reinforcement layer. The adhesive forces were determined using the Zwick Z005 tensile testing machine from Zwick GmbH & Co. KG, Ulm, Germany. For this purpose, the transfer film was adhered flat to the lower holder. The layer to be removed was then removed at a right angle using the tensile test. The removal forces were determined using the load cell.

[0309] Regarding the design of the further layers in Fig. 7 reference is made here to the above statements.

[0310] Fig. 9 shows a film 1 with a carrier substrate 2, an electrically conductive layer 3, an intermediate adhesive layer 11, the decorative layers 12a and 12b, an adhesion-promoting layer 4 and a contact-reinforcing layer 7.

[0311] As in Fig. 9 As shown, the carrier film 2 is flush with the other layers of the film 1 at both ends. The adhesion-promoting layer 4 is, as shown in Fig. 9 shown, present in area 22 and absent in area 20.

[0312] Furthermore, it is possible for the film 1 in the contacting area 20 to be completely or partially printed with an adhesive varnish in a pattern, for example, in a grid. Thus, it is possible for an adhesive varnish to be applied to the contact reinforcement layer 7.

[0313] The adhesive varnish is preferably an electrically conductive adhesive varnish.

[0314] Alternatively, it is also possible for the film 1 to be devoid of the adhesive varnish in the contacting area 20. When the film 1 is applied to a target substrate, the electrical (press) contact (through heat and pressure) is created between the film 1 and the target substrate, particularly in the contacting area 20. It is possible that the electrical (press) contact is permanent due to the bonding, particularly due to the adhesive varnish.

[0315] Regarding the design of the layers in Fig. 9 reference is made here to the above statements.

[0316] Fig. 10 shows a film 1 with a carrier substrate 2, a release layer 13, a protective lacquer layer 6, an electrically conductive layer 3, an intermediate adhesive layer 11, the decorative layers 12a and 12b, an adhesion-promoting layer 4 and a contact-reinforcing layer 7.

[0317] Also the Fig. 10 Slide 1 shown can, like the one in Fig. 9 The foil shown may be completely or partially patterned with an adhesive varnish in the contact area 20. As shown in Fig. 10 As shown, the carrier layer 2 protrudes beyond the other layers of the film on one side. This allows the carrier film 2 to be easily removed after the film 1 has been applied to a target substrate. The separating layer 6 arranged between the carrier layer 2 and the protective lacquer layer 6 enables the carrier layer 2 to be removed.

[0318] Regarding the design of the layers in Fig. 10 reference is made here to the above statements.

[0319] Fig. 11a shows conductor tracks 31, 32 in a top view. The conductor tracks 31, 32 are formed by correspondingly shaped electrically conductive layers 30 made of silver. The conductor tracks 31, 32 have a width 26 between 0.2 µm and 20 µm, preferably between 4 µm and 15 µm, and a distance 27 greater than 10 µm, preferably greater than 20 µm, from one another, so that the conductor tracks 31, 32 are below the resolution of the human eye. The conductor tracks 31a are formed by a first electrically conductive layer and the conductor tracks 32a by a second electrically conductive layer. The conductor tracks 31a form driver conductor tracks and the conductor tracks 32a form sensor conductor tracks. The driver conductor tracks are supplied with an alternating current, for example, by means of a driver circuit.The capacitance generated at the intersection points of the conductor tracks 31a and 32a changes when the foil, which has the electrically conductive layers 30, is touched, for example, by a finger. This is detected by the sensor conductor tracks 32a by means of a sensor circuit connected to the sensor conductor tracks 32a, and the location of the contact or the change in capacitance is determined.

[0320] Fig. 11b shows an enlarged section 30v of the Fig. 11a . The conductor tracks 32 formed by the electrically conductive layer form, as in Fig. 11b shown, three separate contact areas. The three contact areas have, for example, a minimum distance of 0.5 mm from each other, in order to thereby achieve, in particular, electrical insulation of the contact areas. The contact reinforcement layer 7 is applied to the conductor tracks 32. In the Fig. 11b The contact reinforcement layer 7 shown is a layer of carbon conductive ink with a layer thickness of 4.5 µm. Fig. 11b The surface areas occupied by the contact reinforcement layer 7 shown have a size of 0.3 mm x 2.0 mm. The surface areas occupied by the contact reinforcement layer 7 project at least partially beyond the conductor tracks 32, which are widened in the end region. This makes it possible to expand the contacting area formed by the conductor tracks 32, as long as an electrical connection between the contacting area and the contact reinforcement layer 7 is ensured.

[0321] Fig. 12 shows a further design variant of the conductor tracks 31, 32 in plan view. The conductor tracks 31, 32 are formed by correspondingly shaped electrically conductive layers 30 made of silver. As in Fig. 12 As shown, the conductor tracks 31a of the first electrically conductive layer and the conductor tracks 32a of the second electrically conductive layer are structured, in particular structured such that the conductor tracks 31a, 32a of the first and second electrically conductive layers form a plurality of surface elements 33. The surface elements 33 are in Fig. 12 rhombus-shaped or diamond-shaped, so that the first and second electrically conductive layers each have a so-called diamond structure. This diamond structure is, as in Fig. 12 shown, formed by a plurality of diamond-shaped surface elements 33 along linear conductor tracks 31, 32. The first and second electrically conductive layers each have a plurality of spaced-apart diamond structures. The first and second electrically conductive layers are arranged one above the other in such a way that both diamond structures are arranged at right angles to each other, i.e., rotated 90° to each other. The surface elements 33 of the first electrically conductive layer are arranged "on a gap" in the free spaces between the surface elements 33 of the second electrically conductive layer, with the linear conductor tracks 31, 32 of the electrically conductive layers intersecting in the spaces between the surface elements.In this embodiment, an exact position of the surface elements 33 relative to one another is particularly important and the surface elements 33 are preferably arranged in register relative to one another with a tolerance of less than 0.25 mm, preferably less than 0.1 mm.

[0322] As in Fig. 12 As shown, the conductor tracks 31, 32 in the area of ​​the surface elements 33 are shaped according to the shape of the surface elements 33, so that the surface elements are completely filled with the material of the electrically conductive layers. It is also possible for the conductor tracks to run only along the surface elements, so that the surface elements are only framed by the conductor tracks, at least in some areas. The conductor tracks then run, for example, partially straight and then run triangularly in the areas of the surface elements. Furthermore, the conductor tracks 31, 32, as shown in Fig. 12 shown, arranged according to a regular grid, wherein the electrically conductive layers appear at least semi-transparent due to the grid.

[0323] Fig. 13 shows a film 1 with a first electrically conductive layer 3a, a second electrically conductive layer 3b, the carrier substrates 2, a protective lacquer layer 6, the adhesion-promoting layers 4, an intermediate adhesive layer 11 and the contacting regions 7.

[0324] As in Fig. 13 As shown, the electrically conductive layers 3a and 3b are each provided on a carrier substrate 2. The protective lacquer layer 6 is applied to the second electrically conductive layer 3b in some areas, but not to the contacting area. The intermediate adhesive layer 11 is applied to the first electrically conductive layer 3a in some areas. The intermediate adhesive layer 11 covers the functional area formed by the electrically conductive layer 3, but not the contacting area. As shown in Fig. 13 As shown, the carrier substrate 2 with the second electrically conductive layer 3b is applied to the first electrically conductive layer 3a by means of the adhesion-promoting layer 4 and the intermediate adhesive layer 11. The intermediate adhesive layer 11 can also be a protective lacquer layer, so that the first and second electrically conductive layers 3a and 3b are arranged one above the other merely by means of the adhesion-promoting layer 4. The electrically conductive layers 3a and 3b are in Fig. 13 arranged overlapping. The first electrically conductive layer 3a and the second electrically conductive layer 3b are preferably positioned in register with one another, in particular with a tolerance of less than 0.25 mm, preferably with a tolerance of less than 0.1 mm. As already explained, the electrically conductive layers 3a, 3b preferably have conductor tracks arranged according to a grid. This grid can be regular or irregular. The grid can in particular be constructed from grid elements, such as lines and / or surface elements. The grid elements can form so-called sensor cells.

[0325] Regarding the design of the further layers in Fig. 13 reference is made here to the above statements.

[0326] Fig. 14 shows plan views of electrically conductive layers 3a, 3b. 3a relates to a first electrically conductive layer, which can be contacted in the contacting region 20a. 3b further relates to a second electrically conductive layer, which can be contacted in the contacting region 20b. The electrically conductive layers 3a, 3b can, as in Fig. 13 shown, each arranged on a carrier substrate 2. If the two electrically conductive layers 3a and 3b are now arranged one above the other, as indicated in plan view in 3a, b, the two contacting regions 20a, 20b are now arranged next to one another and thus form a common contacting region 20c. With regard to the superimposed arrangement of the electrically conductive layers 3a and 3b, reference is made to the above explanations. The common contacting region 20c is electrically contacted, for example, by means of an adapter element 51. The adapter element 51 is preferably a flexible adapter element 51, which electrically contacts the contact points in the common contacting region 20c and connects them on the outside in an electrically conductive manner to a further contact element 52.The contact between the common contact area 20c and the adapter element 51 is preferably made by means of a connecting element 50 made of conductive adhesive, in particular by means of ACF bonding (ACF = Anisotropic Conductive Film). The further contact element 52 can, for example, be a particularly standardized connector, for example a ZIF connector (ZIF = Zero Insertion Force).

[0327] Fig. 15a und Fig. 15b show process steps for producing an electrical functional element. Fig. 15a shows the use of a film 1 according to the invention for application to a target substrate 10. The target substrate 10 can be, for example, a display. Regarding the design of the layers of the film 1, reference is made to the above explanations. As in Fig. 15a As shown, the film has no adhesion-promoting layer 4 in the region 23. The region 23 thus forms a tail region in which the contacting region 20 is located. As shown in Fig. 15b As shown, the film 1 is applied to the target substrate 10, thereby forming an electrical functional element. If, for example, the electrical functional structure forms a touch sensor field, in particular a capacitive sensor field, which provides a touch panel functionality, and the target substrate is a display, then, for example, a touchscreen can be produced. Fig. 15a In the non-applied state of the film 1 shown, it is possible that the adhesion-promoting layer 4 has a cloudy optical appearance, for example due to a surface roughness of the adhesion-promoting layer 4. After application of the film 1 to the target substrate 10, as in Fig. 15b As shown, the adhesion-promoting layer 4 is now preferably highly transparent and clear, since, for example, the surface roughness of the adhesion-promoting layer 4 has been leveled by the application process. The application of the film 1 can be carried out by hot lamination. Furthermore, it is possible for the film 1 to be applied from a roll to the target substrate 10 by means of hot lamination. The film web speed is preferably between 1.5 m / min and 3.5 m / min. The hot lamination is preferably carried out at a temperature in the range between 80°C and 300°C, preferably between 200°C and 290°C, more preferably between 240°C and 270°C, and / or with an embossing pressure in the range between 200 bar and 2000 bar, preferably between 500 bar and 1500 bar.

[0328] The Fig. 15b The electrical functional element shown can be lifted in the tail region 23 so that the contacting region 20 is safely accessible and can be safely contacted in further steps. In the region 22, which has the adhesion-promoting layer 4, the film 1 adheres to the target substrate 10. In the region 22, the adhesion of the film 1 is at least so strong that the film 1 does not detach from the target substrate 10 during intended use. For example, the adhesion is tesa-resistant, i.e. the adhesive force is so great that the film 1 cannot be removed from the target substrate 10 by tearing in a 90° peel-off process with a tesa 4104 adhesive tape from tesa, Norderstedt, Germany, attached to the film 1. The layers 2, 3, 6 and 4 of the film 1 are transparent so that the target substrate 10 is clearly visible to a human observer through the film 1.If the target substrate 10 is, for example, a thin glass layer or a transparent PMMA layer, the electrical functional element formed by the film 1 and the thin glass layer or the PMMA layer is transparent as a whole. Thus, the electrical functional element composed of the film 1 and the PMMA layer can, for example, have a light transmission of 84.6%, particularly in the wavelength range between 300 nm and 800 nm, preferably between 380 nm and 780 nm, while the PMMA layer alone has a transmission of 93.6%.

[0329] Fig. 16a und Fig. 16b show process steps for the production of an electrical functional element. Fig. 16a und Fig. 16b corresponding to the Fig. 15a und Fig. 15b with the difference that the film 1 additionally comprises the release layer 5. The release layer 5 ensures that the film 1 does not adhere to the target substrate 10 in the area 23. Regarding the design of the release layer 5, reference is made to the above explanations. Fig. 16b Slide 1 shown can therefore be used in the same way as the Fig. 15b shown foil in the area 23 which includes the contacting area 20. In In the area 22, however, the film 1 adheres to the target substrate 10.

[0330] Fig. 17a und Fig. 17b show process steps for the production of an electrical functional element. Fig. 17a und Fig. 17b corresponding to the Fig. 15a und Fig. 15b with the difference that the film 1 additionally comprises the release layer 5, the intermediate adhesive layer 11 and the decorative layers 12a and 12b. Regarding the design of the layers 5, 11, 12a and 12b, reference is made to the above explanations. Fig. 17b Slide 1 shown can therefore be used in the same way as the Fig. 15b The film shown can be lifted in the region 23, which includes the contacting region 20. In the region 22, however, the film 1 adheres to the target substrate 10.

[0331] Fig. 18a und Fig. 18b show process steps for producing an electrical functional element. Fig. 18a shows the use of a film 1 according to the invention for application to a target substrate 10. Regarding the design of the layers of the film 1, reference is made to the above statements. As in Fig. 18a As shown, the film 1 has a full-surface adhesion-promoting layer 4, but the intermediate adhesive layer 11 and the decorative layer 12c are not applied in the contacting area. However, it is also possible for the adhesion-promoting layer 4 to be absent in the area 23a, so that the contacting area can be raised from the target substrate 10, for example, to further facilitate contacting. As shown in Fig. 18b As shown, the film 1 is applied to the target substrate 10, thereby forming an electrical functional element. Fig. 18a In the non-applied state of the film 1 shown, it is possible that the adhesion-promoting layer 4 has a cloudy optical appearance, for example due to a surface roughness of the adhesion-promoting layer 4. After application of the film 1 to the target substrate 10, as in Fig. 18b As shown, the adhesion-promoting layer 4 is now preferably highly transparent and clear, since, for example, the surface roughness of the adhesion-promoting layer 4 has been leveled by the application process. The film 1 can be applied by hot lamination, as already explained. Alternatively to hot lamination, it is also possible for the film 1 to be applied to the target substrate 10 by injecting an injection-molding compound, with the injection-molding compound in particular forming the target substrate 10. This makes it possible for the film 1 to be firmly bonded to the injection-molding compound by the adhesion-promoting layer 4.

[0332] Depending on the design of the target substrate 10, it is possible, for example, for the electrical functional element formed from the film 1 and the target substrate 10 to be a mobile phone, such as a smartphone or a PDA, a tablet computer, an ATM, a ticket machine, a gaming machine, a gaming console, a control panel of a household appliance or a motor vehicle, or, for example, a touchscreen. It is also possible for the electrical functional element to be an input device, in particular a touch panel. It is also possible for the electrical functional element formed from the film 1 and the target substrate 10 to be an intermediate product that is incorporated into or in a final product in further processing steps.The aforementioned electrical functional elements preferably serve for information processing, wherein the information is recorded, for example, by the electrical functional structure designed as a touch sensor field, in the form of the touch position.

[0333] Fig. 19a und Fig. 19b show process steps for producing an electrical functional element. Fig. 19a shows the use of a film 1 according to the invention for application to a target substrate 10. Regarding the design of the layers of the film 1, reference is made to the above statements. As in Fig. 19a As shown, the film 1 has no adhesion-promoting layer 4 in the area 23. The area 23 thus forms a tail area in which the contact area 20 is located. As shown in Fig. 19b As shown, the film 1 is applied to the target substrate 10, thereby forming an electrical functional element. Fig. 19a In the non-applied state of the film 1 shown, it is possible that the adhesion-promoting layer 4 has a cloudy optical appearance, for example due to a surface roughness of the adhesion-promoting layer 4. After application of the film 1 to the target substrate 10, as in Fig. 19b As shown, the adhesion-promoting layer 4 is now preferably highly transparent and clear, since, for example, the surface roughness of the adhesion-promoting layer 4 has been leveled by the application process. The application of the film 1 can be carried out by hot stamping. In this case, it is possible for the film to be applied to the target substrate from a roll or from a sheet by means of hot stamping. Preferably, the hot stamping takes place at a stamping temperature between 80°C and 250°C, preferably between 100°C and 200°C, and / or at a stamping pressure between 0.5 kN / cm 2 and 10 kN / cm 2 . Furthermore, it is also expedient if the stamping time is in a range from 1 ms to 2000 ms, preferably in a range from 1 ms to 500 ms. After application of the film 1 to the target substrate, as in Fig. 19b shown, the carrier substrate 2 is removed. As explained above, the carrier substrate 2 can be detached because the adhesive force between the carrier substrate 2 and the protective lacquer layer 6, due to the separating layer 13 arranged between the carrier substrate 2 and the protective lacquer layer 6, is 20% to 80%, preferably 30% to 70%, smaller than the adhesive force between the protective lacquer layer 6 and the other applied layers of the film, in particular the electrically conductive layer 3 of the intermediate adhesive layer 11 and / or the decorative layers 12a and 12b and / or the adhesion-promoting layer 4.Preferably, the adhesive force between the carrier substrate 2 and the protective lacquer layer 6 is also smaller than the adhesive force between the applied layers of the film, in particular the electrically conductive layer 3 of the intermediate adhesive layer 11 and / or the decorative layers 12a and 12b and / or the adhesion-promoting layer 4, and the target substrate 10 due to the separating layer 13 arranged between the carrier substrate 2 and the protective lacquer layer 6, so that when the carrier substrate 2 is peeled off, the applied layers of the film 1 do not detach from the target substrate 10.

[0334] The Fig. 19b The electrical functional element shown can be raised in the tail area 23 so that the contacting area 20 is safely accessible and can be safely contacted in further steps. In In the region 22, which has the adhesion-promoting layer 4, the film 1 adheres to the target substrate 10. In the region 22, the adhesion of the film 1 is at least so strong that the film 1 does not detach from the target substrate 10 during intended use.

[0335] Fig. 20a und Fig. 20b show process steps for the production of an electrical functional element. Fig. 20a und Fig. 20b corresponding to the Fig. 19a und Fig. 19b with the difference that the film 1 additionally comprises the primer layer 14. Regarding the design of the layers, reference is made to the above explanations. Furthermore, as in Fig. 20b shown, the carrier substrate 2 is not removed after application of the film 1 to the target substrate. Fig. 20b Slide 1 shown can therefore be used in the same way as the Fig. 19b The film shown can be lifted in the region 23, which includes the contacting region 20. In the region 22, however, the film 1 adheres to the target substrate 10.

[0336] Fig. 21a und Fig. 21b show process steps for producing an electrical functional element. Fig. 21a shows the use of a film 1 according to the invention for application to a target substrate 10. Regarding the design of the layers of the film 1, reference is made to the above statements. As in Fig. 21a As shown, the film 1 has no adhesion-promoting layer 4 in the area 20.

[0337] As in Fig. 21a As shown, the target substrate 10 has a contact layer 15, in particular for electrically contacting the at least one contacting region 20 of the film 1. Preferably, the contact layer 15 is applied directly to the target substrate 10. Furthermore, it is possible for the contact layer 15 to have at least one connecting element, in particular an electrical connection, such as a plug. It is also possible for the contact layer 15 to have at least one adapter element and / or contact element. Preferably, the Zielsubstrat 10 already has a contacting structure, in particular for electrically contacting the at least one contacting area 20 of the film 1, in the form of the contact layer 15.

[0338] As in Fig. 21a As shown, the contact layer 15 is arranged in the region 20. The region 20 thus forms a target contacting region, which is the counterpart to the contacting region 20 of the film 1. The target contacting region of the target substrate 10 and the contacting region 20 of the film 1 are, as shown in Fig. 21a shown, particularly after application of the film 1 to the target substrate 10, are congruent. Furthermore, it is also possible that the target contact area of ​​the target substrate 10 and the contact area 20 of the film 1 overlap at least in some areas after application of the film 1.

[0339] Furthermore, the target substrate 10, as shown in Fig. 21a , an electrically conductive layer 3c is shown. The electrically conductive layer 3c preferably has a plurality of conductor tracks, which are preferably arranged according to a grid. This grid can be regular or irregular. The grid can, in particular, be constructed from grid elements, such as lines and / or surface elements.

[0340] Furthermore, it is also possible that the electrically conductive layer 3c has further electrical components, such as antennas, capacitors and inductors.

[0341] As in Fig. 21a As shown, the electrically conductive layer 3c is electrically, in particular galvanically, connected to the contact layer 15. It is also possible for the electrically conductive layer 3c to be connected to the contact layer 15 via a capacitive and / or inductive coupling.

[0342] The contact layer 15 and / or the electrically conductive layer 3c in Fig. 21a is preferably applied to the target substrate 10 by printing, in particular by screen printing. Furthermore, it is also possible for the contact layer 15 and / or the electrically conductive layer 3c to be produced on the target substrate 10 by laser direct structuring (LDS).

[0343] The contact layer 15 preferably consists of an electrically conductive paste, in particular carbon paste, which preferably comprises silver (Ag), gold (Au), aluminum (Al), copper (Cu), chromium (Cr), and / or other conductive metals. Furthermore, it is possible for the electrically conductive paste, in particular carbon paste, to comprise binders, in particular comprising rosin and / or phenolic resins, polymers, and copolymers. Binders of the electrically conductive paste, in particular carbon paste, are natural resins, preferably rosin, phenolic resins, polymers, and copolymers consisting of PVC, PMMA, PU, ​​polyester, and isocyanate (NCO)-crosslinked binders, for example, MF, MPF, melamine-polyester, and UMF. Less preferred are binders of the electrically conductive paste comprising poly(organo)siloxanes and their copolymers and / or radiation-curing binders.

[0344] As in Fig. 21b As shown, the film 1 is applied to the target substrate 10, wherein the target substrate 10, as set out above, comprises the contact layer 10 and the electrically conductive layer 3c.

[0345] By applying the film 1 to the target substrate 10, the contact layer 15 electrically connects the electrically conductive layer 3c of the target substrate 10 to the functional structure of the electrically conductive layer 3 of the film 1 via the contact area 20 of the film 1. The contact layer 15 on the target substrate 10 thus forms the counter-contact to the contact area 20 of the film 1.

[0346] Furthermore, it is possible for the film 1 in the contacting region 20 to be completely or partially printed with an adhesive varnish in a pattern, for example in a grid. Preferably, when the film 1 is applied to the target substrate 10 provided with the contact layer 15, an electrical (press) contact (through heat and pressure) is created between the film 1 and the target substrate 10, in particular in the at least one contacting region 20 and / or target contacting region. It is thus possible for an electrical contact to be created between the contact layer 15 of the target substrate 10 and the contacting region 20 of the film 1. The electrical (press) contact is permanently reinforced by the bonding, in particular by the adhesive varnish. The adhesive varnish is advantageously an electrically conductive adhesive varnish.

[0347] It is also possible to insert an ACF bonding tape between the contacting area 20 of the film 1 and the target contacting area of ​​the target substrate 10. This can further improve the electrical connection in the contacting area 20. It is advantageous if the application process (heat and pressure) largely corresponds to the conventional ACF bonding process.

[0348] As in Fig. 21a und Fig. 21b As shown, the film 1 does not have a tail area that can be easily lifted, for example, by a protruding carrier substrate. Fig. 21a und Fig. 21b The film 1 shown also does not require such a tail region, since it is applied directly to a target substrate 10, which, due to the contact layer 15, already has a mating contact, by means of which an electrical connection can be established between the electrically conductive layer 3 of the film 1 and the electrically conductive layer 3c of the target substrate 10. A tail region is therefore not necessary in this embodiment.

[0349] Regarding the design of the layers in Fig. 21 reference is made here to the above statements.

[0350] Fig. 22a und Fig. 22b show process steps for the production of an electrical functional element. Fig. 22a und Fig. 22b corresponding to the Fig. 21a und Fig. 21b with the difference that the film 1 additionally comprises the separating layer 13 and the protective lacquer layer 6. Regarding the design of the layers, reference is made to the above explanations. Furthermore, as in Fig. 22a shown that the carrier substrate 2 is designed to protrude, so that the carrier substrate 2, as in Fig. 22b shown, can be easily removed after application of the film 1 to the target substrate 10. The Fig. 22a Slide 1 shown will therefore be the same as the one in Fig. 21a The film 1 shown is applied to a target substrate 10 provided with a contact layer 15, whereby an electrical connection is established between the electrically conductive layer 3 of the film 1 and the electrically conductive layer 3c of the target substrate 10.

[0351] Fig. 23a bis Fig. 23d show top views of a target substrate 10, foils 1 and an electrical functional element.

[0352] This shows Fig. 23a a target substrate 10, onto which a contact layer is applied. The contact layer has connecting elements 50. Preferably, the connecting elements 50 are integrated ZIF contacts, which, as in Fig. 23a shown, are connected to an ACF contacting area by means of conductor tracks. Furthermore, it is possible for the target substrate 10 to be transparent. The contact layer comprising the connecting elements 50 is in Fig. 23a For example, by hot stamping. The contact layer of the target substrate 10 is designed such that two foils can be applied to the target substrate 10. Thus, the target substrate 10, to which two foils are to be applied, has Fig. 23a already has a contact layer which is designed in such a way that a two-layer sensor consisting of a film for the x-layer and a film for the y-layer can be applied.

[0353] Fig. 23b shows foils 1, which together form a two-layer sensor. A foil 1 in Fig. 23b forms the x-position, and a film 1 forms the y-position. For example, it is possible for the x-position to comprise x-sensors of a touch sensor, which detect the x-coordinates of a touch, and the y-position to comprise y-sensors of a touch sensor, which detect the y-coordinates of a touch. Regarding the design of the films 1, reference is made to the above explanations.

[0354] As in Fig. 23c As shown, preferably a first film 1, which comprises the first sensor layer, for example the x-layer, is first applied to the target substrate 10, and the electrical contact is established, in particular by means of ACF bonding. Advantageously, the first film 1, in particular the contacting region of the first film, is applied in precise registration with the contact layer, in particular with the connecting elements 50 of the contact layer, of the target substrate 10, which are applied to the target substrate for electrical contact, in particular with the contacting region of the first film.

[0355] As in Fig. 23d As shown, the second film 1, which comprises the second sensor layer, for example the y-layer, is then preferably applied in a separate step in precise registration with the first film 1 or in precise registration with the contact layer, in particular with the connecting elements 50 of the contact layer, of the target substrate 10, which are applied to the target substrate 10 for electrical contact, in particular with the contacting region of the second film 1. In this case, it is possible that adhesive bonding, for example by means of OCA, between the sensor layers can be omitted. The registration accuracy, i.e. the positional accuracy of the second film relative to the first film, is preferably ±350 µm, more preferably ±150 µm, in the x and y directions in order to achieve the desired functionality of the electrical functional element, such as the touch sensor.

[0356] Fig. 24a bis Fig. 24e show process steps for producing a film 1. For this purpose, as in Fig. 24a shown, a carrier substrate 2 is provided. Subsequently, as shown in Fig. 24b As shown, the electrically conductive layer 3 is applied at least partially to the carrier substrate 2. The electrically conductive layer 3 is, for example, a metal layer made of copper. The metal layer 3 is applied here at least in the areas that later form the functional area 21 and the contacting area 20. The metal layer 3 is preferably applied by means of a vacuum metallization process, i.e., the metal layer 3 is vapor-deposited onto the possibly pretreated carrier substrate 2. The pretreatment of the carrier substrate 2 can, for example, be a corona or plasma treatment or the application of a single- or multi-layer adhesion promoter layer. For example, copper as the starting material is heated to temperatures close to its boiling point.The individual atoms, atom clusters, or molecules of copper that are released in this process migrate through a vacuum chamber and deposit on the cooler carrier substrate 2 opposite. This forms a thin layer of the evaporated metal on the carrier substrate 2. By using masks, it is possible to evaporate the metal layer 3 in specific areas. It is also possible to increase the thickness of the thin copper layer formed by vacuum metallization through galvanic reinforcement.

[0357] As in Fig. 24c As shown, the metal layer 3 applied over the entire surface is then structured. For this purpose, photolithographic techniques are preferably used, i.e., the metal layer 3 is removed again in sections by positive or negative exposure and etching or by means of a washing process in order to form the electrical functional structure in the functional region 21 and the contact structure in the contact region 20. For example, to structure the metal layer 3, a photoresist layer is first applied to the metal layer 3. The photoresist layer is then exposed using a mask and a lamp, such as a mercury vapor lamp, or a laser, such as an excimer laser, wherein the exposed areas correspond to the areas in which the metal layer 3 is to be removed.The exposed areas of the photoresist layer are subsequently removed, and an etching step is then performed, which removes the metal layer 3 in those areas where the photoresist layer was removed. The remaining photoresist layer is then removed.

[0358] In a next optional step, as in Fig. 24d shown, a protective lacquer layer 6 and a contact reinforcement layer 7 are applied. The protective lacquer layer 6 and the contact reinforcement layer 7 are cast in sections, for example by means of a slotted caster (= nozzle). Fig. 24d The contact reinforcement layer 7 shown is a layer of carbon conductive ink. Fig. 24d The protective lacquer layer 6 shown is a layer of PAC. However, it is also possible for the protective lacquer layer 6 and the contact reinforcement layer 7 to be applied by gravure printing, such as reverse engraving or reverse roll, screen printing, or relief printing, such as pad printing or flexographic printing. Layers 4, 5, 6, and 7 are preferably physically drying, so it is advantageous, especially before applying a further layer, to allow it to dry first.

[0359] As in Fig. 24e As shown, the adhesion-promoting layer 4 is then applied in the area 22. In the area 23, however, the adhesion-promoting layer 4 is not applied. The adhesion-promoting layer 4 can be printed. Suitable printing methods are gravure printing, screen printing, or letterpress printing. However, it is also possible for the adhesion-promoting layer 4 to be poured into the area 22, for example, using a slotted caster. Optionally, as in Fig. 24e shown, a release layer 5 can be printed, for example by screen printing. The release layer 5 can also be applied by other printing methods, such as gravure or letterpress printing. The release layer 5 can also be applied by means of a slot coater. Fig. 24e The film 1 shown adheres to a target substrate in the area 22 which has the adhesion-promoting layer 4 after application of the film 1 to the target substrate. In In contrast, in the area 23, which comprises the contacting area 20, the film 1 does not adhere to the target substrate. As already explained, the above-mentioned application methods can lead to surface roughness of the adhesion-promoting layer 4, so that the adhesion-promoting layer 4, for example, exhibits light-scattering properties before being applied to the target substrate. In particular, after application of the film 1, the adhesion-promoting layer 4 is highly transparent, since the adhesion-promoting layer 4 is melted, for example, by hot lamination and / or leveled by pressure, such that surface roughness of the adhesion-promoting layer 4 no longer has a disturbing visual appearance.

[0360] Fig. 25a und Fig. 25b show a process step for producing a film 1. For this purpose, as in Fig. 25a shown, the decorative layers 12c and 12d are provided. As already explained, the decorative layer 12c can be, for example, a transparent colored lacquer layer, which is arranged on the decorative layer 12d, which can be formed as a transparent carrier layer. The decorative layers 12c and 12d are applied to the intermediate adhesive layer 11 by means of hot stamping. However, it is also possible for the decorative layers 12c and 12d to be applied to the intermediate adhesive layer 11, for example, by means of cold stamping and / or by means of thermal transfer processes and / or by means of different lamination processes. As in Fig. 25b shown, the carrier layer 12d remains on the film 1. Furthermore, it is also possible that the carrier layer 12d is removed, so that in Fig. 25b only the decorative layer 12c remains on the film 1.

[0361] Fig. 26a bis Fig. 26c show schematic process steps for forming a film and / or an electrical functional element.

[0362] Fig. 26a shows a film 1 which, as explained above, is designed in multiple layers. With regard to the design of the layers, reference is made to the above explanations. Furthermore, it is possible for the film 1 to already be applied to a target substrate and / or intermediate substrate, so that it is an electrical functional element formed from the film 1 and the target substrate and / or intermediate substrate. The film 1 and / or the electrical functional element is formable, in particular by means of the forming processes described below. The target substrate and / or intermediate substrate preferably has a layer thickness of a maximum of 1 mm, more preferably 500 µm, so that the electrical functional element is formable.

[0363] Advantageously, the forming takes place by means of forming processes, preferably by means of deep drawing, thermoforming, high-pressure forming or by means of an injection molding process.

[0364] Preferably, the film 1 and / or the electrical functional element is formed by deep drawing. Fig. 26b This shows, for example, film 1 after forming by deep drawing. Advantageously, the forming of film 1 and / or the electrical functional element is carried out using a vacuum, in particular at a negative pressure of a maximum of 1 bar, and / or by means of overpressure support, in particular at an overpressure between 1 bar and 3 bar, in a forming tool corresponding to the desired forming geometry.

[0365] Furthermore, it is possible for the film 1 and / or the electrical functional element to be formed by thermoforming. Advantageously, the forming process of the film 1 and / or the electrical functional element, or the process parameters of the forming process, correspond to those of deep drawing, wherein the forming is carried out with additional temperature support, in particular at a temperature between 120°C and 300°C, preferably between 190°C and 250°C, for example, when using ABS material. In this case, it is possible for either the carrier substrate and / or the target substrate to comprise ABS material.

[0366] It is also possible for the film 1 and / or the electrical functional element to be formed by means of high-pressure forming. Advantageously, the forming of the film 1 and / or the electrical functional element takes place with the assistance of overpressure, in particular at an overpressure between 1 bar and 300 bar, preferably between 10 bar and 150 bar, in a forming tool corresponding to the desired forming geometry. In this case, it is expedient for the forming to take place with additional temperature assistance, preferably at temperatures in the range of the glass transition temperature of the film 1 used. Advantageously, the temperature is between 120 °C and 300 °C, preferably between 190 °C and 250 °C, for example when using ABS material.

[0367] By means of the above-mentioned forming processes, three-dimensional elongations of the film 1 and / or the electrical functional element of up to 200% are preferably achieved. It is also possible, especially when the parameters are optimized for the respective system, to achieve elongations of up to 300%, although elongations between 20% and 50% are sufficient in many applications.

[0368] As in Fig. 26c The film 1, which has previously been formed or preformed by deep drawing, is shown being back-injected with an injection molding compound 60 in a subsequent injection molding process.

[0369] Furthermore, it is also possible for the film 1 and / or the electrical functional element to be formed and / or deformed by means of an injection molding process. Advantageously, the film 1 and / or the electrical functional element is introduced into the injection mold in a flat state via a roll or from a sheet or via individual labels and is deformed by means of the injection molding process, wherein the shaping takes place in particular by closing the tool and also by injecting the molding compound. In particular, the injection pressure depends on the component geometry and / or the component size. For example, it is possible for the injection pressure to be 500 bar and the injection temperature to be between 180 °C and 380 °C, wherein the injection pressure and injection temperature depend on the injection molding material.Furthermore, it is also expedient for the film 1 introduced into the injection mold and / or the electrical functional element to be heated prior to the closing process of the injection mold by heating the film 1 and / or the electrical functional element, for example at temperatures between 30°C and 300°C, preferably between 80°C and 150°C. It is also possible for the film 1 and / or the electrical functional element to be fitted into the cavity by means of a clamping frame and / or vacuum and / or overpressure.

[0370] It is also advantageous to reshape the film 1 and / or the electrical functional element by "covering" the film 1 and / or the electrical functional element over an already three-dimensionally preformed component. Advantageously, the "covering" of the film 1 and / or the electrical functional element is carried out by controlling a vacuum suction of the film 1 and / or the electrical functional element onto the already three-dimensionally preformed component while simultaneously applying overpressure in a single process. Preferably, the already three-dimensionally preformed component to be covered is previously subjected to a temperature. It is expedient if the overpressure is between 1 bar and 50 bar, preferably between 3 bar and 15 bar, and / or the temperature is between 30°C and 300°C, preferably between 100°C and 180°C.

[0371] Preferably, the film 1 and / or the electrical functional element has an extensibility of greater than 20%. Such high extensibility cannot be achieved, for example, by means of the above-mentioned forming and / or deformation processes with conventional functional films, in particular since the carrier film consists of, for example, PETis not deformable enough and / or the conductive structures break after only slight deformation, particularly at elongations of more than 20%. It has been shown here that the elongation is improved by the film 1 according to the invention. Thus, the multi-layer structure of the film 1 according to the invention, particularly by the at least one electrically conductive layer embedded between several lacquer layers according to a sandwich system, as described above, means that the mechanical elongation and / or deformation can be influenced in a targeted manner, for example by adjusting the layer thicknesses or the lacquer formulations to make certain areas of the film 1 more or less flexible. Thus, the desired elongation of more than 20% is preferably achieved here.

[0372] Even with the above-mentioned three-dimensional deformations, it is advantageous if the electrical functional structure of the film 1 and / or the electrical functional element can be electrically, in particular galvanically, contacted from the outside, for which the electrical contacts must be accessible for contacting. Alternatively, inductive and / or capacitive coupling, in particular coupling via an antenna, can be implemented. As explained above, the film 1 according to the invention enables robust and secure contacting of the electrical functional structure. List of reference symbols

[0373] 1Foil 2Carrier substrate 3, 3a, 3b, 3c, 30Electrically conductive layers 4Adhesion layer 5Release layer 6Protective lacquer layer 7Contact reinforcement layer 8Dielectric layer 9Darkening layer 10Target substrate 11Intermediate adhesive layer 12a, 12b, 12c, 12d, 12e, 12f, 12g, 12h, 12i, 12jDecorative layers 13Separating layer 14Primer lacquer layer 15Contact layer 20, 20a, 20b, 20cContacting area(s) 21Functional area 22, 23, 23a, 24, 25Areas 26Conductor track width 27Conductor track spacing 30vCutout 31, 32, 31a, 32aConductor track(s) 33Surface elements 40Top side 41Bottom side 42, 43Interfaces 50Connecting element 51Adapter element 52Contact element 60Injection molding compound 70Transfer layer

Claims

1. Film (1) comprising a carrier substrate (2), an adhesion layer (4) for applying the film (1) to a target substrate (10) and at least one electrically conductive layer (3), wherein the at least one electrically conductive layer (3) forms an electrical functional structure in a functional region (21), wherein the at least one electrically conductive layer (3) forms at least one contacting structure for contacting the electrical functional structure in at least one contacting region (20), and wherein the adhesion layer (4) does not cover the at least one contacting region (20) at least in certain regions when viewed perpendicularly to a plane spanned by the carrier substrate (2) or wherein the adhesion layer (4) is applied over the entire surface when viewed perpendicularly to a plane spanned by the carrier substrate (2), wherein the at least one electrically conductive layer (3) is arranged between the carrier substrate (2) and the adhesion layer (4) or the adhesion layer (4) is arranged on the side of the carrier substrate (2), said side facing away from the at least one electrically conductive layer (3) and wherein the adhesion layer (4) is arranged on the surface of the film (1), wherein the adhesion layer (4) consists of a material that is highly transparent after application to the target substrate, and the adhesion layer (4) is formed from a hot adhesive or an adhesive that can be cured by radiation.

2. Film (1) according to claim 1, characterised in that the adhesion layer (4) covers the functional region (21) at least in certain regions and / or the adhesion layer (4) does not cover the at least one contacting region (20) over the entire surface and / or the adhesion layer (4) does not cover a region (24) adjacent to the at least one contacting region (20) when viewed perpendicularly to a plane spanned by the carrier substrate (2), and the region (24) adjacent to the at least one contacting region (20) has a width of at least 0.2 mm.

3. Film (1) according to one of the preceding claims, characterised in that the film (1) comprises a detachment layer (5), wherein the detachment layer (5) covers the at least one contacting region (20) at least in certain regions when viewed perpendicularly to a plane spanned by the carrier substrate (2), wherein in particular the detachment layer (5) covers the region (24) adjacent to the at least one contacting region (20).

4. Film (1) according to one of the preceding claims, characterised in that the adhesion layer (4) consists of a material that has a transmission of light in the wavelength range of between 380 nm and 780 nm of more than 85%, preferably more than 90%, after application to the target substrate (10) and / or the adhesion layer (4) consists of a material that is clear after application to the target substrate (10), in particular the adhesion layer (4) consists of a material that deflects light in the wavelength range of between 380 nm and 780 nm by less than 8%, preferably by less than 4% by means of scattering after application to the target substrate (10).

5. Film (1) according to one of the preceding claims, characterised in that the film (1) comprises a protective lacquer layer (6), wherein in particular the protective lacquer layer (6) covers the at least one electrically conductive layer (3) at least in certain regions when viewed perpendicularly to a plane spanned by the carrier substrate (2) and / or wherein in particular the protective lacquer layer (6) is arranged between the at least one electrically conductive layer (3) and the adhesion layer (4).

6. Film (1) according to one of the preceding claims, characterised in that the at least one electrically conductive layer (3) has a contact enhancing layer (7), wherein in particular the at least one electrically conductive layer (3) has the contact enhancing layer (7) in the at least one contacting region (20) at least in certain regions, wherein preferably the contact enhancing layer protects the at least one contacting region (20) from mechanical, physical and / or chemical environmental influences.

7. Film (1) according to one of the preceding claims, characterised in that the film (1) has a transmission of light in the wavelength range of between 380 nm and 780 nm of more than 75%, preferably more than 80%, more preferably more than 85%, yet more preferably more than 90%, after application to the target substrate (10) at least in the one functional region (21) of the at least one electrically conductive layer (3).

8. Film (1) according to one of the preceding claims, characterised in that the electrical functional structure forms a touch sensor field, in particular a capacitive sensor field, which provides touch field functionality.

9. Film (1) according to one of the preceding claims, characterised in that the film has one or more decorative layers (12a-j), wherein in particular the one or more decorative layers (12a-j) are arranged on the side of the carrier substrate (2), said side facing away from the at least one electrically conductive layer (3), and / or the one or more decorative layers (12a-j) are arranged on the side of the at least one electrically conductive layer (3), said side facing away from the carrier substrate (2).

10. Film (1) according to claim 9, characterised in that the one or more decorative layers (12a-j) are substantially arranged in the same region (22) as the adhesion layer (4) and / or an intermediate adhesion layer (11), in particular the one or more decorative layers (12a-j) are substantially arranged congruent to the adhesion layer (4) and / or the intermediate adhesion layer (11) when viewed perpendicularly to a plane spanned by the carrier substrate (2).

11. Film (1) according to one of the preceding claims, characterised in that the film (1) comprises a separating layer (13), wherein in particular the separating layer (13) is arranged between the carrier substrate (2) and the at least one electrically conductive layer (3).

12. Film (1) according to claim 11, characterised in that the separating layer (13) is arranged between the carrier substrate (2) and the protective lacquer layer (6).

13. Film (1) according to one of the preceding claims, characterised in that the film (1) can be reshaped, preferably can be reshaped three-dimensionally, wherein in particular the film (1) can be reshaped by means of a reshaping process, in particular by means of deep-drawing, thermoforming, high-pressure forming or by means of an injection moulding process.

14. Method for producing a film (1), in particular according to one of claims 1 to 13, wherein the method comprises the following steps, which are carried out, in particular, in the following sequence: a) providing a carrier substrate (2); b) applying at least one electrically conductive layer (3) to the carrier substrate (2), wherein the at least one electrically conductive layer (3) forms an electrical functional structure in a functional region (21), wherein the at least one electrically conductive layer (3) forms at least one contacting structure for contacting the electrical functional structure in at least one contacting region (20); c) applying an adhesion layer (4) for applying the film (1) to a target substrate (10) in such a way that the adhesion layer (4) does not cover the at least one contacting region (20) at least in certain regions when viewed perpendicularly to a plane spanned by the carrier substrate (2) or wherein the adhesion layer (4) is applied over the entire surface when viewed perpendicularly to a plane spanned by the carrier substrate (2), wherein in step c), the adhesion layer (4) is applied in such a way that the at least one electrically conductive layer (3) is arranged between the carrier substrate (2) and the adhesion layer (4) or in step c), the adhesion layer (4) is arranged on the side of the carrier substrate (2), said side facing away from the at least one electrically conductive layer (3) and wherein the adhesion layer (4) is arranged on the surface of the film (1), wherein the adhesion layer (4) consists of a material that is highly transparent after application to the target substrate, and the adhesion layer (4) is formed from a hot adhesive or an adhesive that can be cured by radiation.

15. Method according to claim 14, characterised in that in step c), the adhesion layer (4) is applied in such a way that the adhesion layer (4) covers the functional region (21) at least in certain regions.

16. Method according to one of claims 14 to 15, characterised in that, between step b) and step c), the following step is carried out: - applying a contact enhancing layer (7) in such a way that the at least one electrically conductive layer (3) has a contact enhancing layer (7), in particular the at least one electrically conductive layer (3) has the contact enhancing layer (7) in the at least one contacting region (20) at least in certain regions and / or between step b) and step c), the following step is further carried out: - applying a protective lacquer layer (6), in particular in such a way that the protective lacquer layer (6) covers the at least one electrically conductive layer (3) at least in certain regions when viewed perpendicularly to a plane spanned by the carrier substrate (2).

17. Method according to one of claims 14 to 16, characterised in that the method further comprises the following steps: g) applying one or more decorative layers (12a-j), in particular in such a way that the one or more decorative layers (12a-j) are arranged on the side of the carrier substrate (2), said side facing away from the at least one electrically conductive layer (3), and / or the one or more decorative layers (12a-j) are arranged on the side of the at least one electrically conductive layer (3), said side facing away from the carrier substrate (2), wherein in particular in step g), the one or more decorative layers (12a-j) are applied in such a way that the one or more decorative layers (12a-j) are substantially arranged in the same region (22) as the adhesion layer (4) and / or the intermediate adhesion layer (11), in particular the one or more decorative layers (12a-j) are arranged substantially congruent to the adhesion layer (4) and / or the intermediate adhesion layer (11) when viewed perpendicularly to a plane spanned by the carrier substrate (2).