Electronic components on flexible substrates

Abstract

An electronic component (1) is connected to a conductive track (2) on a flexible substrate (3). A connecting layer (4) comprising a composition of a thermoplastic material (TPM1) is arranged on the conductive track (2). The connecting layer (4) has at least one cutout (5), at least one cutout being aligned to overlap the conductive track (2). A liquid thermosetting material (TSM1) is used to fill the cutout (5). The electronic component (1) is arranged on top of the connecting layer (4). By applying heat, the temperature of the connecting layer (4) is raised to above the softening temperature of the thermoplastic material (TPM1). Pressure is applied to form a mechanical connection. By applying heat (H), the temperature of the thermosetting material (TSM1) is raised to above its thermosetting temperature so that the thermosetting material (TSM1) cures and forms an electrical connection (E).

Description

Technical Field

[0001] The present disclosure relates to a method for connecting an electronic component to a conductive track on a flexible substrate. The present disclosure also relates to an assembly of one or more electronic components on a flexible substrate having conductive tracks, and to a garment having integrated electronic components. Background Art

[0002] The transmission of electrical signals to or from electronic components through conductive wiring (e.g., tracks) on flexible and / or stretchable substrates can be hampered by interference from external electromagnetic radiation, variations in the electronic properties (resistance) of the tracks, and unstable interconnections between the electronic components and the wiring on the substrate. Resistance variations and / or faulty interconnections can negatively impact the quality of the transmitted signal.

[0003] U.S. Patent No. 6,449,836 describes a method of interconnecting printed circuit boards, one of which has an insulating substrate made of a thermoplastic resin and a conductive pattern with lands. By overlapping these lands with the lands of a second printed circuit board, an electrical interconnection can be formed, which can be covered with a softened and deformed portion of the thermoplastic resin. However, it can be difficult to manufacture a printed circuit board with an insulating substrate made of a thermoplastic resin. The electrical connection formed by the electrical interconnection generally has poor stability, for example, the formed interconnection is prone to resistance changes or cracking, or even loss of electrical connection, especially when the thermoplastic resin is repeatedly bent and / or stretched.

[0004] There remains a need for further improvements in permanently connecting electronic components to conductive tracks on flexible substrates. Summary of the invention

[0005] Aspects of the present disclosure relate to connections between electronic components and conductive tracks on a flexible substrate. As described herein, a connection layer may be provided on the conductive tracks. The connection layer is preferably formed of a composition comprising a thermoplastic material. The connection layer may have one or more openings extending therethrough. For example, the openings may be present as areas cut out from the connection layer. At least one of the openings may be aligned to at least partially overlap the conductive tracks. Preferably, the connection layer is closely fitted to the flexible substrate such that the connection layer with the cutout and the underlying flexible substrate define a cavity.

[0006] Preferably, a thermosetting material is used to fill the cavity formed by the opening or incision. The thermosetting material can be provided to the incision in a liquid state. Therefore, the connecting layer with the incision can define the volume, shape and / or position of the electrical connection connecting the contact points of the electronic component to the conductive track. It should be understood that the connecting layer is preferably an electrical insulator. Preferably, the thermosetting material is a thick viscous composition, such as a paste. Advantageously, the thick viscous liquid (e.g., a paste) can be retained in the incision at least for the time required to complete the subsequent steps. The thermosetting material is conductive at least when cured. The electronic component can be arranged on top of the connecting layer, for example, so that the contact points of the electronic component are aligned to contact with the thermosetting material filling the incision.

[0007] Preferably, the temperature of the connecting layer is raised to a temperature close to or above the softening temperature (Tg) of the thermoplastic material of the connecting layer. Heating the connecting layer above the softening temperature may cause the connecting layer to soften and thermoplastically deform. For example, the plastic deformation of the connecting layer may improve the contact between the connecting layer and the electronic component on the one hand, and the contact between the connecting layer and the flexible substrate with the conductive tracks on the other hand. After the thermoplastic material is cured, the connecting layer forms a durable mechanical connection between the electronic component and the flexible substrate. In some embodiments, pressure is applied to the softened connecting layer, for example during or after heating. Applying pressure may improve the contact and thereby improve the adhesion of the connecting layer to the electronic component and / or the conductive tracks, respectively. The thermoplastic layer may consist of a plurality of layers, for example an outer layer having a relatively low thermoplastic temperature regime and an inner layer having a relatively high thermoplastic temperature regime. This combination may ensure the structural integrity of the layer during the process. Suitable thermoplastic layers include those for textile applications. Type thermoplastic polyurethane (TPU), which usually has two or three layers, the outer layer is glue, and the inner layer is more stretchable but more thermally stable (e.g., BEMIS prod. #3916).

[0008] Preferably, heat is applied to raise the temperature of the thermosetting material above its thermosetting temperature. Advantageously, this may be the same heat as that used to soften the thermoplastic layer. For example, the temperature increase of the connecting layer may be sufficient to also raise the temperature of the thermoplastic material. Heating the thermosetting material above its thermosetting temperature may trigger the curing of the thermosetting material. In this way, the thermosetting material may advantageously form an electrical connection between the contact points of the electronic component and the conductive tracks on the flexible substrate. It will be appreciated that the electrical connection in the cutout may be mechanically decoupled from the mechanical connection between the electronic component and the flexible substrate, thereby further improving durability.

[0009] Alternatively, a pressure sensitive adhesive (PSA) can also be applied as a conductive adhesive. This is a material that reorganizes under pressure so that the conductive particles in the adhesive form percolation paths, thereby obtaining bulk conductive properties. For thermosetting materials based on PSA, pressure during the lamination process can be used to obtain conductivity. Temperature can be applied to form mechanical interconnections between components (e.g., a flexible substrate with printed tracks and an electronic component).

[0010] In some preferred embodiments, the flexible substrate itself is also formed by a composition comprising a thermoplastic material. This can in principle be the same material as the connecting layer, or can include a different second thermoplastic material. The use of a flexible substrate formed by a thermoplastic material advantageously enables the flexible substrate to be adhered to another substrate, such as a flexible carrier and / or layer, as will be explained below. In one embodiment, the softening temperature (e.g., glass transition temperature) of the second thermoplastic material of the flexible substrate is different from the softening temperature of the thermoplastic material of the connecting layer, for example, at least 5 degrees Celsius or more higher or lower than the softening temperature of the thermoplastic material of the connecting layer. Using a substrate having a softening temperature higher than the softening temperature of the connecting layer can prevent the flexible substrate from being plastically deformed during the softening of the connecting layer. Therefore, the manufacturing process including adhering the flexible substrate to the carrier can be performed in a separate process step. Alternatively, using a substrate having a softening temperature lower than the softening temperature of the connecting layer can enable, for example, the adhered substrate to be removed from the carrier by heating to a temperature between the softening temperature of the flexible substrate and the softening temperature of the connecting layer, without reducing the adhesion of the connecting layer.

[0011] In other or further preferred embodiments, a flexible layer of thermoplastic material is applied to the component and the connecting layer and heated to form a covering layer. Preferably, the covering layer is beveled to form a gradual decrease in the total stack thickness from the electronic component to the outside. It should be understood that for the connecting layer, the flexible layer of thermoplastic material preferably has a softening condition within a range lower than or approximately up to the softening condition of the thermoplastic material contained in the flexible substrate and / or the connecting layer, respectively. In this way, temperature and pressure can be applied so that the covering layer can be plasticized and adhered to the electronic component without melting and / or degrading any components or layers below. Providing a covering layer advantageously makes the surface topology present on the outer surface of the electronic component flush. This protects the various components on the electronic component from damage (e.g., contact damage) and / or makes the outer surface of the electronic component and the stack as a whole smoother to the touch. It should be understood that the covering layer can further help to alleviate the stress that may be concentrated (e.g., accumulated) on the track at a position close to the edge of the electronic component during use, such as during the bending and / or stretching of the flexible substrate. Preferably, at least a portion of the covering layer is formed to have an inclined surface, i.e., a gradually decreasing thickness. The gradually tapered thickness may further improve the overall stiffness of the stack of layers and components by providing a gradual decrease in the lateral surface direction, thereby helping to relieve stress on the conductive tracks and / or reduce stress concentrations on the conductive tracks. Thus, the cover layer may improve the service life of the connection by reducing the likelihood of delamination and / or damage to the conductive tracks, particularly along the edges of the electronic components.

[0012] Some aspects of the present disclosure may be embodied as an assembly in which an electronic component is connected to at least one conductive track on a flexible substrate. For example, the assembly may be obtained by a product or intermediate product of one of the methods disclosed herein, or by other methods. The assembly generally includes a connecting layer on the conductive track. For example, the connecting layer is formed by a composition comprising a thermoplastic material. Preferably, the connecting layer has at least one cutout, and the at least one cutout is aligned to overlap at least partially with the conductive track. The assembly may include a cured conductive thermosetting material in the cutout, such as filling the cutout. The electronic component is arranged on top of the connecting layer, wherein the contact point of the electronic component is aligned to contact with the thermosetting material, such as a cured thermosetting material. In the assembly, the connecting layer forms a mechanical connection between the electronic component and the flexible substrate and / or the conductive track on the flexible substrate. The connecting layer may be plastically deformed at least at the interface with the electronic component and / or the flexible substrate. The plastic deformation of the connecting layer may advantageously improve the contact and / or adhesion between the connecting layer and the electronic component and / or between the connecting layer and the flexible substrate, respectively. In the assembly, the electrical connection connects the contact point of the electronic component and the conductive track on the flexible substrate. The electrical connection is formed through a thermoset material, such as a cured thermoset material.

[0013] In a preferred embodiment, the flexible substrate is durably connected to a carrier, preferably a textile sheet.Thus, aspects of the present disclosure relate to a garment, preferably a garment comprising an assembly as described herein with an electronic component connected to at least one conductive track on a flexible substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] These and other features, aspects, and advantages of the apparatus, systems, and methods of the present disclosure will become better understood from the following description, appended claims, and accompanying drawings, in which:

[0015] Figures 1A to 1D A method for connecting electronic components to conductive tracks on a flexible substrate is schematically shown;

[0016] FIG. 2A to FIG. 2B A perspective view and a top view showing electronic components and a flexible substrate with conductive tracks on a carrier;

[0017] FIG. 3A to FIG. 3D A method for connecting electronic components to conductive tracks on a flexible substrate is schematically shown;

[0018] Figure 4A A schematic top view of an assembly showing a printed circuit board connected to a flexible substrate having conductive tracks;

[0019] Figure 4B shows a schematic top view of an embodiment in which a plurality of electronic components are connected to a flexible substrate having printed conductive tracks;

[0020] Figure 5A a schematic cross-sectional side view showing the location of a conductive track through an embodiment;

[0021] Figure 5B shows a schematic top view of an embodiment of an electronic component formed by a PCB provided with a sensor chip, the PCB being connected to three conductive tracks on a flexible substrate;

[0022] FIG. 6A to FIG. 6B a photograph depicting a piece of textile material forming a portion of a garment;

[0023] Fig. 7A shows a schematic top view of an embodiment in which a plurality of electronic components are connected to a flexible substrate having printed silver tracks;

[0024] Figure 7B Shows Fig. 7A A close-up top view of an embodiment of the invention during an intermediate state of the manufacturing process;

[0025] Figure 8shows a cross-sectional side view of an embodiment of an assembly of electronic components on a flexible substrate 3 comprising conductive tracks 2;

[0026] FIG. 9A to FIG. 9B The force-strain trace and the resistance variation with time are shown, respectively. DETAILED DESCRIPTION

[0027] The terms used to describe specific embodiments are not intended to limit the present invention. As used herein, the singular forms "a", "an" and "the" are intended to also include plural forms unless the context clearly indicates otherwise. The term "and / or" includes any and all combinations of one or more of the relevant listed items. It should be understood that the terms "include" and / or "comprise" specify the presence of the features described, but do not exclude the presence or addition of one or more other features. It should also be understood that, unless otherwise stated, when a particular step of a method is referred to as being after another step, it may be directly after the other step, or one or more intermediate steps may be performed before performing the particular step. Similarly, it should be understood that, unless otherwise stated, when describing a connection between structures or components, the connection may be established directly or through an intermediate structure or component.

[0028] The present invention is described more fully below with reference to the accompanying drawings, in which embodiments of the invention are shown. In the accompanying drawings, the absolute and relative sizes of systems, components, layers and regions may be exaggerated for clarity. Embodiments may be described with reference to schematic and / or cross-sectional views of possible idealized embodiments and intermediate structures of the present invention. In the description and drawings, the same reference numerals always represent the same elements. Relative terms and their derivatives should be interpreted as referring to orientations as described subsequently or as shown in the drawings discussed. These relative terms are for convenience of description, and unless otherwise stated, the system is not required to be constructed or operated in a specific orientation.

[0029] Figures 1A to 1D A method for connecting an electronic component 1 to a conductive track 2 on a flexible substrate 3 is schematically shown. Figures 1A to 1D Intermediate products and cross-sectional side views of the products obtained at various stages of the process are depicted in FIG.

[0030] In some embodiments, for example, Figure 1A As shown, a connecting layer 4 is arranged on the conductive track 2. Preferably, the connecting layer 4 is formed of a composition comprising a thermoplastic material TPM1. The connecting layer 4 has at least one cutout 5. The at least one cutout 5 can be aligned to at least partially overlap the conductive track 2, for example as shown in the figure.

[0031] In other or further embodiments, for example Figure 1BAs shown, the thermosetting material TSM1 is arranged in the cutout 5, that is, in the volume defined by the flexible substrate 3 with the conductive tracks 2 and the side walls of the cutout 5. Preferably, the thermosetting material TSM1 is arranged in a liquid state (such as ink or paste) to the cutout 5. The thermosetting material (TSM1) is conductive at least when cured. It should be understood that in Figure 1B In the process, the thermosetting material TSM1 may still be in a liquid and / or uncured state. Optionally, the method may include at least partially drying (ie reducing the solvent content) the thermosetting material TSM1 in the cutout 5 before thermosetting the thermosetting material TSM1 in the cutout 5 .

[0032] In other or further embodiments, for example Figure 1C As shown, the electronic component 1 is placed on top of the connection layer 4. In one embodiment, the contact points 7 (e.g., contact pads or contact pins) of the electronic component 1 are aligned to contact the thermosetting material TSM1 in the cutout 5. Note that before applying heat (see Figure 3D ) (ie before the connection layer is plastically deformed), there may be gaps (V) between the connection layer 4 and the electronic component 1 and between the connection layer 4 and the flexible substrate 3, for example, as shown in the figure.

[0033] In other or further embodiments, for example Figure 1D As shown, heat H is applied to raise the temperature of the connection layer 4 to above the softening temperature Tg of the thermoplastic material TPM1 contained in the connection layer 4. For example, the heat can be applied by providing the assembly in an oven. During or immediately after heating, pressure P is optionally applied to form a mechanical connection M between the electronic component 1 and the flexible substrate and / or the conductive track on the flexible substrate by plastic deformation of the connection layer.

[0034] In a preferred embodiment, the application of heat H also raises the temperature of the thermosetting material TSM1 above its thermosetting temperature Ts to harden (e.g. cure) the thermosetting material TSM1 and form electrical connections between the contact points of the electronic component and the conductive tracks on the flexible substrate. It is also conceivable to apply separate or additional heat to initiate the thermal curing process. It will be appreciated that during the manufacturing method, the temperature is preferably such that the connecting layer 4 retains its overall shape, i.e. bulk flow and / or bulk melting of the connecting layer 4 is preferably prevented above a temperature. Note that the application of heat and pressure improves the contact between the layers and generally reduces the gap V (see Figure 1C Note that the product formed after applying the heat may also be referred to as an assembly 30 of the electronic component 1 connected to at least one conductive track 2 on the flexible substrate 3.

[0035] As described herein, a flexible substrate may be understood as a substrate comprising physical properties and / or wearing properties similar or close to the physical properties and / or wearing properties of a fabric or textile layer (e.g., a woven fabric such as a cotton sheet or a knitted (e.g., Eurojersey) textile). The three-dimensional structure of the textile (woven or knitted) enables the adhesive layer of the thermoplastic material and / or the thermoplastic layer itself to be effectively interlocked in the textile, thereby forming a strong connection. Such a flexible substrate may be understood as being repeatedly bent at a radius of curvature of at least 5 mm, preferably lower, such as 3 mm or 2 mm, or even lower, as low as 0.5 mm, such as 1 mm, without losing structural and / or functional integrity (e.g., tearing or splitting). In addition, the flexible substrate preferably includes tensile properties similar or close to the tensile properties of the fabric or textile layer. Therefore, such a flexible substrate may be understood as being stretchable to at least 5%, such as 8%, preferably even greater, such as a relative elongation in the range of up to 10% or even 25%, without losing structural and / or functional integrity (e.g., tearing or splitting). Preferably, the flexible substrate has a modulus similar to that of the fabric or textile layer, for example, a modulus within an order of magnitude (e.g., between one tenth and ten times) of the modulus of the fabric or textile layer. A substrate having bendability and / or stretchability similar to that of the fabric or textile layer can be adhered to the fabric or textile without significantly affecting the properties of the fabric or textile, such as wearing comfort.

[0036] Figure 2A and Figure 2B A perspective view and a top view of an electronic component 1 and a flexible substrate 3 with conductive tracks 2 on a carrier 20 are shown, respectively. For illustrative purposes, the electronic component 1 is depicted in a translucent state to reveal the structure below. In some embodiments, for example as shown in the figure, the flexible substrate 3 is also formed by a composition comprising a thermoplastic material, which in principle can be the same material as the material contained in the connecting layer 4 (e.g., thermoplastic material TPM1). Alternatively, the flexible substrate 3 can be formed by a composition comprising a different second thermoplastic material TPM2. The use of a flexible substrate 3 formed by a thermoplastic material can advantageously enable the flexible substrate 3 to be adhered to another substrate (such as a carrier 20), a flexible carrier and / or a fabric layer, as will be explained below. In one embodiment, the softening temperature (e.g., glass transition temperature) of the second thermoplastic material TPM2 is higher than the softening temperature of the first thermoplastic material TPM1, for example, at least five degrees Celsius or more higher than the softening temperature of the first thermoplastic material TPM1.

[0037] In a preferred embodiment, the carrier is a non-thermoplastic material, such as a thermosetting or cross-linked polymer film. The use of a carrier of a non-thermoplastic material advantageously makes the manufacturing process more robust, for example, in which the carrier can be processed at relatively high temperatures, for example, at a temperature in the range between one hundred and one hundred and fifty degrees Celsius. The use of a non-thermoplastic substrate, for example, enables printing one or more conductive tracks on the substrate and / or annealing one or more conductive tracks without deforming the substrate. Alternatively or in addition, the use of a non-thermoplastic substrate enables, for example, electronic components to be adhered to the substrate over a wide temperature range without the risk of substrate deformation. In addition, the use of a non-thermoplastic substrate enables, for example, the pre-bonded assembly of the substrate and the electronic component to be thermoplastically bonded to another carrier by a bonding layer of a thermoplastic material, or the pre-bonded assembly of the substrate and the electronic component is directly bonded to a thermoplastic carrier, reducing the risk of negatively affecting the bonding with the electronic component, for example, when heat is applied in an anisotropic manner, for example, from a direction away from the bonded electronic component.

[0038] In a preferred embodiment, the conductive track is printed on a flexible substrate (3). Preferably, the conductive track is flexible and / or stretchable to a similar extent as the flexible substrate without substantially losing conductivity. Alternatively, the conductive track may be formed from a bulk metal film, such as a bulk metal film formed in a vapor deposition process. Bulk metal tracks may be susceptible to irreversible damage, such as cracking, when overstretched and / or bent (e.g., stretched to an elongation of more than 1.05 times, or a bending radius of less than 100 nm). Preferably, the conductive track is stretchable and / or bendable by at least 1.10 times and / or more than a bending radius of less than 50 nm, respectively. In a preferred embodiment, the flexible substrate and the conductive track have flexibility and / or stretchability similar to that of a woven fabric or fabric used for clothing.

[0039] In a preferred embodiment, the printed conductive track is formed from a composition comprising discrete conductive particles (e.g., conductive ink or paste). Upon hardening (e.g., curing), the composition preferably achieves a suitable overall conductivity, wherein a composition having a suitable conductivity can be understood as a material having a resistivity less than about 0.1 times the resistivity of the corresponding bulk material. Suitable compositions include, but are not limited to, inks and / or pastes comprising carbonaceous particles and / or metal particles such as silver or copper particles.

[0040] Printing may be understood to include methods such as printing, screen printing, inkjet deposition of a suitable ink or paste template in a pattern to form the conductive track. Conveniently, the printing of the track can provide a variety of shapes and / or sizes of conductive tracks, further improving the flexibility and / or stretchability of the conductive track, for example by providing an appropriate thickness and / or by providing a specific shape such as a meandering track.

[0041] The cutouts 5 in the connecting layer 4 may be provided by any suitable means including but not limited to cutting, laser cutting, die cutting. Alternatively, the connecting layer 4 may be formed around the cutouts 5, for example by hot moulding the thermoplastic material TPM1 in a suitable mould.

[0042] In some embodiments, the cutouts are preferably at least as large as the contact points 7 on the electronic component 1, and more preferably larger than the contact points 7 on the electronic component 1. Using cutouts 5 that are at least as large as the contact points 7 can advantageously reduce the complexity during filling the cutouts with the thermosetting material (TSM1), such as alignment accuracy, and / or simplify positioning of the electronic component 1 on the filled cutouts 5. It should be understood that in the case where the electronic component 1 includes a plurality of contact points, the connection layer 4 is preferably also provided with a plurality of contact points, whereby the cutouts 5 are arranged in a pattern matching the relative positions of the contact points 7, for example as shown in the figure.

[0043] In some embodiments, the typical size of the cutout is in the range of about 0.5 mm by about 0.5 mm up to about 5 mm by about 5 mm. For example, the cutout can be formed as a rectangular cutout with a size of 1 mm by 1 mm, 1 mm by 3 mm, 2 mm by 2 mm, 3 mm by 5 mm, or a circle with a diameter of 4 mm. It should be understood that other shapes and sizes can be used.

[0044] In some preferred embodiments, the size of the cutout and / or the conductive track 2 is determined according to the function of the electrical connection E to be formed. For example, the size of the electrical connection E to be used for powering the electronic component 1 is preferably with a relatively larger cross-section, i.e. a larger cutout, compared to the electrical connection E on which data (e.g. sensor data or processing instructions) will be transmitted. Similarly, the size of the conductive track 2 to be used for powering the electronic component 1 is preferably with a relatively larger cross-section, e.g. wider, compared to the conductive track 2 on which data (e.g. sensor data or processing instructions) will be transmitted.

[0045] In a preferred embodiment, the provided thermosetting material (V TSM1 ) and the volume of the cutout (V 切口 ), that is, the area of ​​the cutout multiplied by the thickness of the connecting layer. Overfilling may result in a short circuit between adjacent conductive interconnects, and underfilling may result in no electrical connection between the electronic component and the conductive track. A certain amount of underfilling can be tolerated. It has been found that under the influence of pressure (e.g. lamination pressure), electrical connection can still be formed despite the theoretical underfilling of the cutout 5. Therefore, V TSM1 Preferably at V 切口 0.5 to 1.1 times, preferably within V 切口 0.7 to 1.05 times, most preferably V 切口 between 0.9 and 1 times.

[0046] The volume of thermosetting material TSM1 can be provided by any suitable means, for example by dispensing. The thermosetting material TSM1 can be dispensed by any method suitable for dispensing liquids or pastes. These include, but are not limited to, syringe dispensing or micro-dispensing and additive manufacturing methods such as printing. In a preferred embodiment, the volume of thermosetting material TSM1 is dispensed by printing, for example template printing. Advantageously, the connecting layer 4 with the cutouts 5 can be used as a template, which not only defines the position and shape, but also defines the volume of the applied thermosetting material TSM1. The use of the connecting layer 4 with the cutouts 5 further reduces the need to provide a separately patterned template.

[0047] The softening temperature can be understood to correspond to the glass transition temperature. The glass transition is generally understood to be a gradual and reversible transition from a hard and relatively brittle "glass" state to a viscous or rubbery state as temperature increases in an amorphous material or an amorphous region within a semi-crystalline material. Typically, the glass transition temperature, Tg, of a material can characterize the small range of temperatures over which this glass transition occurs. Depending on the material, the difference in stiffness below and above Tg can be several orders of magnitude. Although different definitions of Tg may differ by several degrees Celsius (Kelvin), it will be qualitatively clear that once a critical threshold within the range over which the glass transition occurs is exceeded, the material will be more plastic or more susceptible to plastic deformation. To resolve the ambiguity of the relative temperatures used herein, the glass transition temperature can be defined with reference to viscosity, fixing Tg at 10 12 The value of Pa·s.

[0048] Preferably, the composition in the assembly is selected so that the respective softening condition of any of the individual layers (depending on T and P) is lower than the melting temperature of the thermoplastic material contained in the remaining layers. For example, the softening temperature of the connecting layer 4 is preferably lower than the melting temperature of the flexible substrate. Melting and the associated possible uncontrolled flow of the thermoplastic material under the influence of temperature and / or applied pressure can thereby be prevented. For example, a temperature range of about 0.9 to 1.1 times Tg can provide satisfactory adhesion.

[0049] It will be appreciated that the combination of elevated temperature and applied pressure is applied for a time sufficient to plastically deform the connection layer 4, e.g. a thermoplastic material comprised therein, to form a mechanical connection between the electronic component and the flexible substrate and / or conductive tracks on the flexible substrate.

[0050] In a preferred embodiment, the plasticizing (softening) conditions, such as the temperature Tg and / or pressure of the connecting layer, match the softening conditions of the flexible substrate. Bringing both the connecting layer and the flexible substrate to (e.g., heating to) above their respective softening conditions can improve mechanical connection, such as adhesion. Without being bound by theory, the improved mechanical connection can be explained by partial interlocking of polymer chains contained in the substrate and the layer during the plasticizing step.

[0051] In another or further preferred embodiment, the thermosetting temperature Ts of the thermosetting material is below the softening temperature Tg of the flexible substrate 3 and the connection layer 4. Therefore, the curing of the thermosetting material TSM1 and the formation of the mechanical connection M between the electronic component 1 and the flexible substrate 3 can be advantageously obtained in a single process step. As described above, when the thermosetting material TSM1 is cured (solidified), the electrical connection E is formed, for example by sintering the conductive particles contained in the thermosetting material TSM1. Therefore, the electrical connection E and the mechanical connection M can be formed in a single process step.

[0052] In a preferred embodiment, pressure and heat are applied in a laminating device. For example, between opposing pressure surfaces (e.g. laminating plates or rollers) a stack is placed, the stack comprising: a flexible substrate 3 with conductive tracks 2; a connecting layer 4 with one or more cutouts in which a volume of thermosetting material TSM1 is provided; and an electronic component 1, all positioned so that an electrical connection E can be formed between the conductive tracks 2 and one or more contact points 7 of the electronic component 1.

[0053] It should be understood that the method can be used to connect an electronic component 1 having a plurality of contact points 7 to a flexible substrate 3 provided with at least a corresponding number of conductive tracks 2. Therefore, in a preferred embodiment, the connection layer 4 is provided with a plurality of cutouts 5, each of which is aligned to overlap with each conductive track 2, and each of which matches the position overlapping with the contact point 7 provided on the electronic component 1.

[0054] Figure 3A A schematic cross-sectional side view of an electronic component 1 having a plurality of contact points 7 located on top of a connection layer 4 having a plurality of cutouts 5, each of which is filled with a volume of thermosetting material TSM1 is depicted. The connection layer 4 is located on a flexible substrate 3 having a plurality of conductive tracks 2. As shown, the tracks and cutouts are sized and positioned such that the contact points 7 overlap with the thermosetting material TSM1, and the thermosetting material TSM1 overlaps with the conductive tracks 2. Figure 1C Similarly, the stack of components and layers shown shows a stage in the production process before heat is applied. Figure 1CCompared to the stack in the figure, the connecting layer 4 is relatively larger, for example, covering a larger part of the flexible substrate 3. Therefore, in one embodiment, for example, as shown in the figure, the connecting layer 4 is larger than the electronic component. For example, the length and / or width of the connecting layer 4 is preferably at least 1.05 times, for example, between 1.1 times and 1.8 times, or between 1.2 times and 1.5 times, of the corresponding cross-sectional dimensions of the electronic component 1 on the connecting layer 4. Providing a connecting layer 4 that is larger than the electronic component 1 can increase the adhesion between the electronic component 1 and the flexible substrate 3 after applying heat and / or pressure, for example, a stronger mechanical connection. Using a larger connecting layer can increase the adhesion between the electronic component 1 and the flexible substrate 3 after applying heat and pressure (such as Figure 3B ), providing a connection layer region that extends beyond the edge of the electronic component 1 in the cross-sectional direction. This provides an enlarged contact area between the connection layer and the electronic component on the one hand, and between the connection layer and the flexible substrate with conductive tracks on the other hand. In addition, due to the plastic deformation of the connection layer, the electronic component 1 can be partially embedded in the connection layer (for example, as shown in FIG. Figure 3B As shown). Advantageously, providing a connection layer 4 that is larger than the electronic component helps to improve the stability of the mechanical connection M connection between the electronic component 1 (e.g., a rigid electronic component (1)) and the underlying flexible substrate 3. In some embodiments, the mechanical connection between the electronic component 1 and the flexible substrate 3 can be improved by more than just expanding the contact area between them. Expanding the contact area and / or partially embedding the electronic component 1 in the connection layer 4 can help to alleviate stresses on the track that are established at locations close to the edges of the electronic component 1, for example during bending and / or stretching of the flexible substrate 3. The extended portion of the connection layer 4 provides a gradual reduction in the overall stiffness of the stack of layers and components in the lateral surface direction, thereby reducing the possibility of delamination and / or damage to the wiring, especially along the edges of the electronic component 1. It should be understood that although in FIG. 3A to FIG. 3B In the embodiments, the flexible substrate 3 can also be partially embedded in the connecting layer 4, which is not necessarily the case in all embodiments and depends on the size of the flexible substrate 3 relative to the electronic component 1 and / or the presence of a possible carrier adhered to the flexible substrate 3.

[0055] Figure 3C A schematic cross-sectional side view of a stack is depicted, comprising: an electronic component 1 with a plurality of contact points 7; a connection layer 4 with a plurality of cutouts 5, each filled with a volume of thermosetting material TSM1; and a flexible substrate 3 with conductive tracks 2. Figure 3A As in the embodiment of FIG. 1 , the contact points 7 overlap with the thermosetting material TSM1, and the thermosetting material TSM1 overlaps with the conductive tracks 2. A flexible layer of thermoplastic material TPM3 is provided on top of the stack. Figure 1C and Figure 3A Similarly, the stack of components and layers shown illustrates a stage in the production process prior to the application of heat.

[0056] Figure 3D A schematic cross-sectional side view of the stack after applying heat and pressure is depicted. In a preferred embodiment, for example, as shown in the figure, a flexible layer of thermoplastic material TPM3 is applied over the electronic component 1 and the connecting layer 4. Under the influence of the applied heat and pressure, the flexible layer of thermoplastic material TPM3 can be plasticized and form a covering layer 8. Preferably, the covering layer is inclined to form a gradual decrease in the thickness of the total stack from the electronic component 1 to the outside, for example, from a position close to the edge of the electronic component 1 to a more outer position closer to the flexible substrate 3. It should be understood that for the connecting layer 4, the softening condition (e.g., Tg, P) of the flexible layer of thermoplastic material TPM3 is preferably below the softening condition of TPM1 and TPM2 respectively contained in the flexible substrate and the connecting layer or approximately up to the softening condition of TPM1 and TPM2 respectively contained in the flexible substrate and the connecting layer. In this way, temperature and pressure can be applied so that the covering layer 8 can be formed and adhered to the electronic component 1 without melting or deteriorating any component or layer below. Providing a covering layer can advantageously flatten the surface topology present on the outer surface of the electronic component 1, which can protect individual parts on the electronic component 1 from damage, such as contact damage, and / or make the outer surface of the electronic component (1) and the stack as a whole smoother to the touch. It should be understood that the covering layer can help, for example, during bending and / or stretching of the flexible substrate 3 to relieve stresses established on the track at a position close to the edge of the electronic component 1. A portion of the covering layer 8 has an inclined surface, i.e. a gradually decreasing thickness, thereby providing a gradual decrease in the overall stiffness of the stack of layers and components in the lateral surface direction. Therefore, the covering layer can improve the service life of the electronic component 1 electrically connected to the conductive track 2 on the flexible substrate 3 by reducing the possibility of delamination and / or damage of the wiring, especially along the edge of the electronic component 1. The covering layer (8) can be shaped as a pyramid or a truncated pyramid, or any other shape that provides a gradual decrease in thickness. A layer with a gradually decreasing thickness can be understood as a layer with a slope (in cross section) in the range of between 10 degrees and 70 degrees, such as between 20 degrees and 70 degrees. Having a slope within a preferred range of between 25 and 60 degrees, such as 45 or 60 degrees, can effectively reduce stress on layers below the inclined layer without requiring an overly large cover layer, such as a cover layer with a very gentle slope (eg, about 5 degrees).

[0057] In some preferred embodiments, the cover layer is formed with the plasticization of the connection layer 4 and / or the thermosetting of the thermosetting material TSM1, i.e., in a single process step. For example, a flexible layer of thermoplastic material TPM3 can be placed on a stack comprising an electronic component 1 and a stack of connection layers and then laminated with the stack. Alternatively, the flexible layer of thermoplastic material TPM3 can be arranged on the electronic component 1 and the connection layer 4, respectively, after a mechanical and / or electrical connection is formed between the electronic component 1 and the flexible substrate 3 having the conductive track 2. In other words, the cover layer can be formed in a separate (subsequent) process step. Alternatively, the cover layer 8 can be formed in a separate process step, for example, by reheating the formed cover layer 8 and molding (e.g., pressurizing) the cover layer into a desired shape. Preferably, the shape is defined with the formation of the cover layer, i.e., in the same process step, for example, during the lamination step.

[0058] In some embodiments, the desired shape (e.g., a truncated pyramid) can be obtained by providing a mold of an appropriate shape between a flexible layer of thermoplastic material and a corresponding laminate for lamination. In a preferred embodiment, during the application of heat and pressure, a mold covering the electronic component 1 is applied between the flexible layer of thermoplastic material and a corresponding pressure surface (e.g., a pressure surface of a laminator device). Preferably, the mold is a flexible sheet, such as a porous flexible sheet, such as a sponge. In one embodiment, providing a porous flexible sheet such as a sponge between the flexible layer of thermoplastic material and the corresponding pressure surface (e.g., a laminate) i) can be used to reduce stress on the electronic component 1 during the application of pressure, and ii) in-situ compression of the porous flexible sheet to form a mold, which shapes the cover layer 8 to form a 3D shape that gradually slopes downward from the component toward the flexible substrate 3.

[0059] In some embodiments, the relative thickness of the flexible layer of thermoplastic material TPM3 forming the cover layer in the layer is at least three times the thickness of the connecting layer 4. As previously mentioned, the function of the connecting layer 4 includes defining the shape and size of the electrical connection E to be formed by the thermosetting material TSM1 inside the cutout. Another function of the connecting layer 4 is to provide a mechanical connection between the electronic component 1 and the flexible substrate 3. Further functions may include eliminating possible height variations between the conductive track 2 and the flexible substrate 3, and eliminating height differences on the surface of the electronic component 1 facing the conductive track 2. This height difference may be caused by the surface topology of one or more contact points 7 of the electronic component 1 or the thickness of the printed conductive track 2. Therefore, the minimum thickness of the connecting layer 4 can be defined by this height difference. In addition, the minimum thickness can be defined by practical considerations, such as preventing the connecting layer 4 from tearing and / or wrinkling during the processing of the layer, especially when setting the cutout 5. On the other hand, the maximum thickness can be defined by the conductivity of the electrical connection E connecting the electronic component 1 to the conductive track 2. As the thickness of the connecting layer 4 increases, a conductive connection of gradually increasing length (and a gradually increasing associated resistance) will be formed. In some embodiments, a good electrical and mechanical connection can be formed using a connection layer 4 having a thickness between 50 and 500 microns, preferably in the range between 100 and 300 microns, for example about 200 or about 250 microns. The minimum thickness of the cover layer 8 depends on the desired stress relief properties, while the desired minimum residual flexibility of the conductive track 2 may define the maximum thickness of the cover layer 8 and, therefore, the maximum thickness of the flexible layer of thermoplastic material TPM3. In other or further embodiments, good protective properties can be obtained for a method using a layer of thermoplastic material TPM3 having a thickness between 500 and 3000 microns, preferably between 750 and 2000 microns, more preferably in the range between 1000 and 1500 microns, for example about 1200 or about 1300 microns.

[0060] In a preferred embodiment of the method, at least two preferably all thermoplastic materials in the thermoplastic material are formed by a composition showing overlapping plasticizing conditions. Plasticizing conditions can be understood to include softening temperatures, such as glass transition temperature, particularly at a temperature within the range of -10 degrees Celsius below the glass transition temperature to +10 degrees Celsius above the glass transition temperature. In certain embodiments, the softening temperature of the thermoplastic material varies with the applied pressure. For example, the reduced temperature (such as up to 5 degrees) below the glass transition temperature range of a given material can be compensated by applying an increased contact pressure (such as during a lamination step). Vice versa, the excessive flow of the material exposed to a slightly elevated temperature (such as up to 5 degrees higher than the preferred range of the material) can be compensated by providing a relatively small contact pressure. Without being bound by theory, plasticization generally occurs in a temperature range close to the glass transition temperature (Tg) or near the glass transition temperature (Tg). In practice, it is found that plasticization is a function of the modulus of temperature, applied pressure and a given material.

[0061] In certain embodiments, the method includes arranging one or more intermediate glue layers. One or more intermediate glue layers can be advantageously used to adhere (connect) the layer in the stack (assembly) and / or to connect the assembly to a carrier such as a textile sheet. For example, in one embodiment, the intermediate glue layer is arranged to the face away from the electronic component of the flexible substrate, for example, to the bottom surface of the stack, for example, the back side of the flexible substrate. The adhesive is arranged to the bottom surface of the stack (for example, the back side of the flexible substrate) so that the stack including the electronic component can be adhered to the carrier or the target substrate. In certain embodiments, the glue layer comprises a pressure-sensitive adhesive composition, for example, a pressure-sensitive adhesive (PSA), or a heat-activated adhesive composition, for example, a heat-activated adhesive (TSA). Preferably, the composition comprises a heat-activated adhesive composition, for example, TSA. In a preferred embodiment, the activation temperature of the adhesive composition is within the range described herein, so that the stack including the electronic component can be adhered to the carrier or the target substrate in a single process step. Preferably, wherein the adhesive composition is a thermoplastic adhesive composition, for example, comprising a thermoplastic material as described above. Thermoplastic adhesive composition is set so that when applying heat to reach the softening temperature of glue, the stacked body comprising electronic components can be removed from carrier or target substrate. In certain embodiments, adhesive is selected as the activation temperature with the softening temperature lower than flexible substrate, connecting layer and / or cover layer 8. Use the adhesive with the softening temperature lower than flexible substrate 3, connecting layer 4 and / or cover layer 8 to enable the stacked body comprising electronic components 1 to be removed, without damaging stacked body and / or carrier (target substrate). It should be understood that intermediate adhesive layer as herein described may include composition or similar composition, or may even include the composition identical with thermoplastic material as herein described (TPM1, TMP2 and TPM3). Alternatively, intermediate adhesive layer may include thermosetting adhesive composition.

[0062] In other or further preferred embodiments, the conductive tracks are arranged in parallel directions, for example Figure 2A and Figure 2B As shown. By setting the conductive tracks along parallel tracks, the positioning accuracy can be reduced, that is, the positioning accuracy is reduced during the manufacture of the connection layer 4. In addition, the flexible substrate 3 including parallel conductive tracks 2 can be provided to improve the flexibility at the position to be connected to the electronic component 1. Preferably, the length of the parallel tracks at least exceeds the lateral dimension of the electronic component 1. The conductive tracks 2 along the parallel tracks can be provided to enable, for example, adjustment before lamination, such as fine-tuning the positioning of the electronic component 1. For example, the position of the electronic component 1 is fine-tuned relative to the expected position on the target substrate. For example, during manufacturing, the connection layer 4 can be freely translated along any position on the parallel tracks, so that the electronic component 1, such as a sensor, is placed more freely relative to the flexible substrate 3 below. The use of a flexible substrate with parallel conductive tracks can be particularly beneficial for manufacturing clothing with different clothing sizes (confection size). For example, for clothing such as shirts with components 1 provided at specific locations, such as on sleeves near the elbows, the use of a flexible substrate with parallel conductive tracks can enable the manufacture of clothing with different sizes (such as clothing sizes) without using a flexible substrate 3 of different sizes for each clothing size.

[0063] In some preferred embodiments, the thermosetting material (TSM1) comprises a conductive adhesive material, preferably an isotropic conductive adhesive. In some embodiments, TSM1 is a conductive adhesive material, preferably an isotropic conductive adhesive. Providing a conductive adhesive material improves the electrical connection E between the conductive track 2 and the contact point 7 of the electronic component 1. Providing an isotropic conductive adhesive (ICA) can ensure that electrical connections E are formed within the cutout 5, each with a predictable, similar resistance; preferably, the resistance is within a standard deviation of five percent.

[0064] In some embodiments, the method includes connecting the flexible substrate to a carrier 20, preferably a sheet of textile 21. Preferably, the carrier or textile sheet includes a relatively rough surface finish, such as a fabric. Providing a carrier with a relatively rough surface can improve the adhesion of the flexible substrate 3 to the carrier. Preferably, the method includes applying heat to raise the temperature of the flexible substrate 3 to at least the softening temperature, and applying pressure to form a durable mechanical connection between the flexible substrate 3 and the carrier. Optionally, the connection with the carrier 20 is formed in a single heating step (i.e. in a single lamination step). Preferably, the electronic components are first connected to the conductive tracks on the flexible substrate. At a later stage, for example after (a portion of) a piece of clothing is completed, the assembly of electronic components on the flexible substrate (or multiple) can be connected to the carrier, such as a textile. Optionally, the assembly of the electronic components connected to the conductive tracks on the flexible substrate can be adhered to the carrier using an intermediate glue layer 25, for example as described above.

[0065] Other aspects of the present disclosure relate to an assembly (30) of an electronic component (1) connected to at least one conductive track (2) on a flexible substrate (3). Preferably, the assembly can be obtained by any of the methods described herein, for example Figure 1D , Figure 3B and Figure 3D The assembly shown. The assembly comprises a connecting layer 4 on a conductive track 2, wherein the connecting layer 4 is formed by a composition comprising a thermoplastic material TPM1. The connecting layer 4 has at least one cutout 5, wherein at least one cutout 5 is aligned to at least partially overlap the conductive track. The assembly further comprises a solidified thermosetting material TSM1 in the cutout 5, preferably filling the cutout, wherein the thermosetting material TSM1 is conductive. An electronic component 1 is arranged on top of the connecting layer 4, wherein a contact point 7 of the electronic component 1 is aligned to contact the thermosetting material TSM1 in the cutout. In the assembly, a mechanical connection M between the electronic component 1 and the flexible substrate and / or the conductive track on the flexible substrate is formed by plastic deformation of the connecting layer. In addition, an electrical connection E between the contact point 7 of the electronic component 1 and the conductive track 2 on the flexible substrate 3 is formed by the solidified thermosetting material TSM1.

[0066] It should be understood that the assembly can further include any of the other elements and / or layers, including the cover layer 8 and / or the intermediate glue layer, as described herein with respect to the disclosed method. Conversely, it should be understood that the method involves and / or can include any one or more of the components, layers and elements described with reference to the assembly.

[0067] In a preferred embodiment, the conductive track 2 is printed on a flexible substrate. In some embodiments, the conductive track is a composite track comprising a layered structure of printed conductive tracks. Providing a layered structure in the conductive track can reduce the resistance and / or improve the flexibility of the track. For example, providing a layered structure can increase the cross-section, thereby increasing the thickness of a track with a given width. In a preferred embodiment, the layered structure is formed by repeatedly depositing, for example printing a layer of a given material (e.g., conductive silver ink) along the track. In some embodiments, the layered structure comprises layers of different components. In a preferred embodiment, the layered structure comprises a silver layer and a conductive carbon layer, and more preferably, the conductive silver layer is sandwiched, for example embedded between layers of a conductive carbon component.

[0068] In another or further preferred embodiment, the electronic component may be understood as a preassembled system comprising a plurality of electronic components, such as a printed circuit board (PCB) 10 provided with interconnected microelectronic components. Alternatively, the electronic component may be understood as comprising a PCB arranged to receive one or more microelectronic components.

[0069] Figure 4A A schematic top view of an assembly 30 is shown in which an electronic component 1 is connected to at least one conductive track 2 on a flexible substrate 3. In the assembly shown, the electronic component 1 is formed by a printed circuit board 10, which is provided with a plurality of microelectronic components 1a, 1b. The microelectronic components are connected to the conductive tracks 2 by integrated interconnects 11 and contact points 7. Note that for clarity, other layers and elements including a connection layer and interconnects connecting the component 1b to the track are not shown. Therefore, in a preferred embodiment, an assembly (and method) is provided in which the printed circuit board includes a plurality of microelectronic components. The PCB preferably includes an integrated interconnect, such as a copper track, which electrically interconnects the microelectronic components to and / or connects the components to the contact points 7 to contact the conductive tracks 2. The integrated interconnect has a relatively high conductivity and / or a short communication distance compared to printed tracks. Therefore, fast and / or low noise communication between electronic components on the PCB can be carried out on short, low resistance paths on the PCB, such as copper tracks, while power supply to the PCB and external communication with components on the PCB can be carried out on long, flexible conductive tracks, such as printed silver tracks.

[0070] Advantages of using a PCB include: multiple electronic components, including but not limited to sensors, actuators, microprocessors, power regulators and memory can be combined into a single component (PCB) and connected to a flexible carrier by connections that are less complex than connecting all the components individually. Thus, a PCB can be understood to include pre-assembled sensor modules, actuator modules, data processing and / or data storage modules, etc.

[0071] In a preferred embodiment, the assembly 30 comprises a plurality of laterally spaced apart electronic components 1 , such as PCS. The electronic components, such as sensor modules, can be electrically connected to each other via one or more conductive tracks 2 .

[0072] Figure 4B A schematic top view of an embodiment of an assembly 30 is shown, in which a plurality of electronic components 1 are connected to a flexible substrate 3 with printed conductive tracks 2. In the embodiment shown, the assembly 30 is adhered to a carrier 20. In a central position, a receiving pad 12 is provided, which is electrically connected to the electronic components 1 via the conductive tracks 2.

[0073] Therefore, in a preferred embodiment, the conductive track 2 electrically connects the electronic component 1 to the receiving pad 12. It should be understood that the receiving pad 12 can be interpreted as an electronic component 1, and / or can include a plurality of microelectronic components on a PCB or any other suitable platform. It should be understood that the landing pad 12 is preferably mechanically and electrically connected to the flexible substrate 3 and the conductive track 2 on the flexible substrate 3, for example by using one or more of the methods described herein.

[0074] In some embodiments, the receiving pad 12 is provided with one or more of the following: i) a power supply unit, such as a battery, for powering the electronic component 1 through the conductive track 2, and ii) an electronic readout and / or controller unit, arranged to read data from the electronic component 1 (e.g., a sensor), and / or send instructions to the electronic component 1. In a preferred embodiment, the receiving pad 12 is a landing pad, the size of the landing pad is specified and the landing pad is arranged to reversibly accommodate one or more target modules. The target module includes, but is not limited to, a display, a data processing and / or data storage element, a power supply unit, a (wireless) data transceiver, and a combination of the foregoing. Providing a landing pad of a specified size and arrangement to reversibly accommodate the pads of the target module can advantageously enable an operator to replace or temporarily place / remove (e.g., when it is expected that external conditions may damage these modules) these modules. For example, in an application where the component 30 is adhered to a textile 21, such as clothing, the module can be removed before a washing cycle. It should be understood that the receiving pad 12 is preferably not completely covered by the cover layer 8 to be able to accommodate and / or remove the target module.

[0075] In some embodiments, for example, Figure 4BAs shown, at least a portion of the back side of the flexible substrate 3 is permanently connected to a carrier 20, preferably a sheet of textile 21. For a flexible substrate formed by a composition comprising a thermoplastic material, a connection can be formed on a thermoplastically deformed portion of the flexible substrate 3, for example by applying heat to raise the temperature of the flexible substrate 3 to at least the softening temperature, and applying pressure to form a permanent mechanical connection between the flexible substrate 3 and the carrier. Optionally, the connection to the carrier 20 (textile 21) is formed by an intermediate adhesive layer. Without being bound by theory, a particularly permanent mechanical connection can be formed with a textile (e.g., a woven fabric). When a portion of the thermoplastic material TPM1 is plasticized (e.g., melted), a portion of the material penetrates between and / or into the fibers contained in the textile (woven fabric) contained in the textile (woven fabric).

[0076] Figure 5A (Top) shows a schematic cross-sectional side view of the assembly 30 at a location passing through the conductive track 2 (i.e. away from the connecting layer 4), wherein a protective layer 9 is provided to cover the conductive track 2 to protect the track 2 from external damage, such as scratches. Optionally, the protective layer 9 can be provided to cover (protect) one or more of the electronic component 1, the cover layer 8 and the flexible substrate 3.

[0077] Figure 5A (bottom) shows a schematic cross-sectional side view of the assembly 30, wherein a protective layer 9 covers the flexible substrate 3 and partially covers the underlying carrier 20. In a preferred embodiment, the protective layer (9) is formed of a composition comprising a thermoplastic material. In some embodiments, the protective layer 9 is laminated to the stack and / or the underlying carrier 20. The protective layer is provided to protect the top surface of one or more conductive tracks from external damage (e.g. damage caused by scratching). Providing the protective layer 9 to also partially cover the underlying carrier 20 can improve the adhesion of the flexible substrate 3 to the carrier 20. Optionally, multiple protective layers 9 can be provided. In other or further preferred embodiments, the protective layers 9 are arranged to form a shielding layer that protects the conductive tracks 2 and / or the electronic components 1 from electronic interference, for example by providing a stack of conductive protective layers 9 sandwiched between electrically insulating protective layers 9.

[0078] It should be understood that compositions based on thermoplastic polyurethane (TPU) may be particularly suitable for the components and methods disclosed herein. Thermoplastic polyurethane (TPU) may be understood as any class of polyurethane plastics. TPU plastics are generally elastic, transparent, and resistant to oil, grease and wear. Technically, they are thermoplastic elastomers composed of linear multi-block copolymers, which consist of hard segments and soft segments. The fact that TPU is a thermoplastic also enables it to be melted, processed, and then cooled to a solid. TPU resins contain linear polymer chains of block structure. This chain forms fairly long segments (called soft segments) that alternate with hard segments. The two types of segments are linked together by covalent bonds so that they form block copolymers. In the resin, the hard segments are orderly aggregated to form crystalline or pseudo-crystalline regions located in a soft and flexible matrix. Depending on the polarity and molecular weight of the flexible chain, production conditions, etc., this so-called phase separation between the two blocks can be more or less important. The crystalline or pseudocrystalline regions act as physical crosslinks which are responsible for the high elasticity level of TPU, while the flexible chains impart elongation properties to the polymer.

[0079] Thus, one or more of the thermoplastic material TPM1 contained in the connecting layer 4, the second thermoplastic material TPM2 contained in the flexible substrate 3, the thermoplastic material TPM3 contained in the layer forming the cover layer 8, the thermoplastic material contained in the protective layer 9, and the thermoplastic material in the intermediate adhesive layer are preferably formed by a composition comprising a thermoplastic polyurethane TPU. Advantageously, a wide range of thermoplastic polyurethanes are commercially available, from which materials can be selected that exhibit specific properties, including melting and glass transition temperatures, stiffness, optical appearance and resistance to water and / or chemicals (solvents). In addition, it is known that a given type of TPU layer can be well adhered (laminated) to a TPU layer of a similar type. Without wishing to be bound by theory, this can be explained by the entanglement of the polyurethane chains in one layer with the chains in an adjacent layer due to the mobility provided to the chains during the plasticizing (heating) step.

[0080] As will be explained below for many applications, it may be beneficial to provide an assembly of (multiple) electronic components (such as one or more sensors) on a flexible substrate 3, each connected to a central receiving pad 12. In some embodiments, the conductive track 2 is along a longer track between two electronic components 1, such as between a sensor module and a receiving pad 12. In a preferred embodiment, the lateral spacing between the electrically connected electronic components 1 (such as between a sensor and a receiving pad 12) is between 5cm and 100cm, preferably between 10cm and 50cm, such as about 20cm or about 40cm. As the distance between the interconnected electronic components 1 increases, the resistance of the track may increase. It will be appreciated that the resistance of the track, particularly for printed tracks, such as silver tracks, may depend on the conduction of bending and / or strain of the flexible substrate and the conductive track 2. Depending on the level of the electrical signal transmitted on the track, changes in resistance (such as due to bending and / or stretching) may have a negative impact on the quality (noise) of the communication or power signal transmitted on one or more tracks.

[0081] Figure 5B A schematic top view of an embodiment of an electronic component 1 connected to three conductive tracks 2 on a flexible substrate 3 is shown. The electronic component 1 is formed by a PCB provided with a sensor chip 15. A power supply (POW) line and a ground (GRND) line of the sensor chip 15 are connected to the wider conductive tracks 2 on the flexible substrate 3. A communication line (COMM) is connected to the narrower conductive tracks 2, which is used, for example, to send and receive instructions and / or sensor data to and from the sensor chip 15. The PCB is further provided with a shifter 13 and a DC-DC converter 14, each of which is electrically connected between the electronic component 1 and the conductive tracks 2 to respectively shift the voltage of the communication signal, such as the sensor data transmission, from an initial level to a higher level, and to shift down the power supply voltage provided via the conductive tracks 2 before transmitting the power supply voltage provided via the conductive tracks 2 to the electronic component 1.

[0082] In a preferred embodiment, the assembly 30 comprises a shifter 13, which is connected to the conductive track 2, preferably to a track used as a data line. In other or further preferred embodiments, the assembly comprises a DC-DC converter 14 to shift down the supply voltage of the electronic component 1, which is arranged on the conductive track 2, preferably on a track used as a power line. The use of a DC-DC converter enables the electronic component 1, such as a PCB, to be powered with an elevated input voltage, for example in a range of about 30V, such as between 5V and 60V. At a location close to the relevant electronic components, for example on a PCB board where a sensor module is arranged, the voltage level may be shifted down to the normal operating voltage of such a component, for example about 1.5V or 1.8V. By shifting down the supply voltage close to the relevant electronic components, external interference, such as a negative impact on the printed track, can be reduced. Similarly, the use of a shifter enables a voltage level, for example the voltage level of the output signal of the sensor module (approximately 1.5V, for example 1.8V) to be shifted up to a level (in the range between 5V and 30V, for example 12V) that is less susceptible to interference from external conditions acting on the conductive track 2.

[0083] According to another aspect, the present disclosure is directed to a garment comprising any one or more of the components 30 described herein.

[0084] Fig. 6A Depicted is a photograph of a sheet of textile 21 forming part of a garment 40. Laminated onto the textile is an assembly comprising two electronic components 1 and receiving pads 12, each connected to a conductive track 2 on a flexible substrate 3. The white dashed line schematically indicates the outline of a transparent cover layer 8 provided over the electronic components 1.

[0085] Figure 6B Shows Fig. 6A 1. A more detailed close-up of the area marked in. In this close-up, the transparent cover layer 8 and several individual components on the PCB forming the electronic component 1 can be seen.

[0086] It should be understood that the methods and / or assemblies described herein can be particularly useful for integrating one or more electronic components into a textile sheet (e.g., clothing). As disclosed herein, a method for incorporating a microelectronic electronic component or multiple electronic components into clothing is provided. By using a connection layer 4 and / or a flexible substrate 3 as described herein, a method is provided that forms a permanent mechanical connection between clothing and an electronic component while simultaneously providing a permanent electrical connection, for example, from a remote receiving pad 12 to the component. Advantageously, under the disclosed method, the electrical connection can be mechanically separated according to the bending or stretching condition of the flexible substrate 3 and / or a carrier, such as a textile. Contemplated clothing includes, but is not limited to, straps, including headbands, chest straps, and wristbands; headwear, including hats; sportswear, including shirts, pants, etc.; footwear, including socks and shoes; and casual and formal wear. Incorporating an electronic component 1, such as a plurality of electronic components 1 (such as the components described herein, including sensors) into clothing worn by a person can be used to assess the condition, position, and / or state of clothing and / or a person or a particular body part. Depending on the type, number and / or distribution of sensors on the garment, the position, velocity and / or acceleration of a person or one or more specific body parts of the person (e.g., limbs and / or torso) can be evaluated. Determining the (relative) position and / or velocity of a person, his limbs, and / or acceleration can be used to evaluate the posture or movement of the person, such as during exercise and / or during revalidation. For example, during a specific exercise, the posture or movement of the arm can be evaluated by a shirt having sensors (e.g., accelerometers, gyroscopes, etc.) distributed along the length of the shirt sleeve. Depending on the orientation of the sensor, such as facing or facing away from the wearer's skin area, clothing can be used to evaluate body functions, including temperature, skin conductivity, heart rate, EEG and / or ECG. It should be understood that the outer surface of the sensor will not be completely covered (e.g., closed) for applications requiring external contact, such as skin contact or contact with body fluids such as sweat. It should be understood that the components and methods described herein (including but not limited to methods and components formed by laminating layers containing TPU) can perform particularly well under harsh conditions, including repeated washing cycles in laundries.

[0087] Fig. 7A A schematic top view of an exemplary embodiment of an assembly 30 of a flexible substrate 3 is shown, the flexible substrate 3 having printed silver tracks 2 to which a plurality of electronic components 1 are connected. In a central position, a receiving pad 12 is provided, which is electrically connected to the electronic components 1 distributed along the limbs of the assembly. The assembly is shaped to a size and form that will enable the assembly to be incorporated into a T-shirt, wherein the two limbs flow through the sleeves of the shirt and the center line is located at the chest position of the shirt.

[0088] Figure 7B shows that during an intermediate stage of the manufacturing process, Fig. 7ADetailed view of the central part of the assembly in FIG. 1 , i.e. with the connection layer 4 in place, but before all the electronic components 1 are placed. In this embodiment, a set of four parallel conductive tracks 2, of which the two outer relatively wide tracks are power lines POW, and the two inner relatively narrow tracks are for data communication COMM. The tracks are printed on the The conductive tracks are formed by printed silver composition layers, which are sandwiched between printed carbonaceous material layers (see for details) Figure 8 ). The connection layer 4 is formed by a 170 micron thick TPU3916 film provided with cutouts 5 at positions corresponding to the tracks below and the contact points 7 of the electronic component 1 to be positioned on the TPU3916 film. In a central position, the receiving pad 12 is positioned above the connection layer 4. In a subsequent processing step, the TPU-portofino sheet is positioned on top of the electronic component 1 and the receiving pad. This layer, which has a thickness of 1.1 mm, will protect the wiring to the electronic component 1 and the receiving pad 12, respectively, during lamination, and / or protect them from delamination, for example, from the flexible substrate 3.

[0089] Figure 8A cross-sectional view of an embodiment of an assembly of an electronic component 1 on a flexible substrate 3 including a conductive track 2 is shown. A stack of laminated layers is laminated to a sheet of Eurojersey textile 21 using an intermediate glue layer 25 formed of TPU3961. The upper half of the image depicts the layers around the electronic component 1 within the assembly, and the lower half of the image shows the build-up at a location away from the electronic component 1 (i.e. at the wiring). In the stack, the conductive track 2 has been set to the flexible sheet of TPU11C 3 by printing. The conductive track is formed as a sandwich structure of a conductive silver track 2a between two carbonaceous layers 2b. A connecting layer 4 of TPU3916 is set on the track. Inside the cutout 5 in the connecting layer 4, a certain volume of ICA (TSM1) forms an electrical connection E between the conductive track 2 and the contact point 7 of the electronic component 1. A protective layer 9 formed by Portofino protects the conductive track 2 from damage. The protective layer 9 can be pre-cut to the desired shape and size, for example using laser cutting. The KrystalFlex cover layer 8 on the electronic component 1 gradually slopes downwards to the side. The stack was laminated in an OPTEC DPL-24A vacuum laminator with a lamination area of ​​60x60cm. A further embodiment of a textile with an integrated PCB comprises the following layers / components in order: i) Eurojersey textile 21; ii) an intermediate glue layer 25 of TPU Bemis 3916, about 100 microns thick; iii) a flexible substrate 3 of TPU Bemis ST604, about 100 microns thick, with conductive tracks on the flexible substrate 3. Tracks patterned by laser ablation of Taiyo TR70901 silver composition; iv) a TPU Bemis 3916 connecting layer (4), about 100 microns thick, filled with a certain volume of ICA (product number WCA 21336-18c); v) a PCB component 1, covered by a 1.4 mm thick TPU Krystalflex cover layer 8. A protective layer 9 is provided on the connecting layer 4. Optionally, you can use The ICA516IE acts as an isotropic conductive adhesive.

[0090] Alternatively, lamination can be performed using a film press (Lotus Hot Press LTS 1575M). In either case, an additional panel can be placed inside the laminator to facilitate the process of positioning the TPU and printing the tracks. The additional panel (e.g., commonly used medium density fiberboard (MDF)) is preferably covered with a polyfluorinated polymer (e.g. etc.) sheets to prevent water (moisture) in the additional panels from affecting the lamination process.

[0091] A vacuum-based laminator is preferred to reduce bubble formation in or between layers due to volatile outgassing during lamination. The thus formed examples were dynamically stretched in a series of 1000 cycle loading tests to characterize the electrical resistance of the conductive tracks and the reliability of the electrical connection E. The parameters characterized were as follows: sample length: 115 mm; cyclic stretch test: 1000 times, each time to 10% strain; stretching speed: 500 mm / min.

[0092] Fig.9A The recording of the first (continuous dark line) and last (dashed line) force-strain traces is shown. The loading slope during the first cycle (dashed and dotted lines, respectively) was 10708 N / m, and the unloading slope measured in the last cycle (1000th) was 7433 N / m. The residual strain was 3.5%.

[0093] Fig. 9B The change in resistance measured between a contact point on the PCB and the end of the conductive track 2 over time, i.e. during repeated loading cycles, is shown. The initial resistance, i.e. before the first loading cycle, was determined to be 27 ohms. The resistance after 1000 stretching cycles and a 5 minute relaxation period was about 55 ohms. The results show that the sample can be stretched dynamically with stable resistance and reliable interconnection. For example, the observed resistance change can match the observed residual strain and meet normal use conditions, under which smaller strains are usually applied, such as strains of up to about 5% or less, such as strains of up to 3%.

[0094] In some preferred embodiments, the manufacturing process may include a series of lamination steps. For example, in some embodiments, a flexible substrate 3 having a conductive track 2 is laser cut into a desired contour. A connecting layer 4 (e.g., TPU 3916) is laser cut into a desired corresponding contour, wherein a cutout 5 is laser cut at a desired location. The connecting layer 4 having the cutout 5 is then assembled on top of a textile sheet, wherein a printed track is laser cut between the connecting layer 4 and the textile sheet. The stack is then laminated using a vacuum laminator (this is the first lamination step). The electronic component 1 (sensor board on the PCB) is then placed on the track, with an ICA 516IE in the cutout 5 and a 1.27 mm thick TPU Krystalflex layer (covering layer 8) on the circuit board. The stack is then laminated using a vacuum laminator in a second lamination step. In the third vacuum lamination step, a protective layer 9 (Portofino, prod#7215) is adhered to the stack, ultimately creating a garment with integrated sensors connected by conductive tracks.

[0095] In some embodiments, the stability of the electrical tracks may be improved after exposure to repeated washing cycles. For example, testing was performed at a temperature of 30°C for up to 10 washing cycles.

[0096] For the purpose of clear and concise description, features are described herein as part of the same or separate embodiments, however, it should be understood that the scope of the invention may include embodiments having all or some combinations of the described features. For example, although embodiments are shown for TPU, those skilled in the art who benefit from the present disclosure may also conceive of alternative ways to achieve similar functions and results. For example, other thermoplastic compositions or combinations of thermoplastic materials, such as sealants, may be used. In addition, electronic components may be combined or split into one or more alternative components. The various elements of the embodiments discussed and shown provide certain advantages, such as improved stability of electrical contacts on a flexible substrate connected to a rigid electronic component. Of course, it should be understood that any of the above-described embodiments or processes may be combined with one or more other embodiments or processes to provide even further improvements in finding and matching designs and advantages. It should be understood that the present disclosure provides specific advantages for garments having one or more integrated electronic components, and can generally be applied to any application in which rigid components are to be integrated, such as adhered to a flexible substrate.

[0097] In interpreting the appended claims, it should be understood that the word "comprising" does not exclude the presence of other elements or actions than those listed in a given claim; the word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements; any figure mark in a claim does not limit the scope of the claim; several "means" may be represented by the same or different items or structures or functions implemented; unless otherwise specifically stated, any of the disclosed devices or parts thereof may be combined together or divided into further parts. When one claim refers to another claim, this may indicate synergistic advantages achieved by the combination of their respective features. However, the fact that certain measures are recorded in mutually different claims does not indicate that a combination of these measures cannot be used to advantage. Therefore, the present embodiment may include all working combinations of the claims, each of which may in principle refer to any preceding claim unless the context clearly excludes it.

Claims

1. A method for connecting an electronic component (1) to a conductive track (2) on a flexible substrate (3), the method comprising: - providing a connecting layer (4) on the conductive track (2), wherein the connecting layer (4) is formed by a sheet comprising a thermoplastic material (TPM1), wherein the connecting layer (4) has at least one cutout (5), wherein the at least one cutout (5) is aligned so as to at least partially overlap the conductive track (2); - at least partially filling the at least one cutout with a liquid thermosetting material (TSM1), wherein the thermosetting material (TSM1) is electrically conductive at least when cured; - subsequently positioning the electronic component (1) on top of the connection layer (4), wherein the contact points (7) of the electronic component (1) are aligned in contact with the thermosetting material (TSM1) in the cutout (5); - applying heat (H) to raise the temperature of the connection layer (4) above the softening temperature (Tg) of the thermoplastic material (TPM1) of the connection layer (4) and applying pressure (P) to form a mechanical connection (M) between the electronic component (1) and the flexible substrate and / or the conductive tracks on the flexible substrate by plastic deformation of the connection layer; wherein the application of heat (H) also ensures that the temperature of the thermosetting material (TSM1) is raised above the thermosetting temperature (Ts) of the thermosetting material so that the thermosetting material (TSM1) cures and forms an electrical connection (E) between the contact point (7) of the electronic component (1) and the conductive track (2) on the flexible substrate (3).

2. The method according to claim 1, wherein: The length and / or width of the connecting layer (4) is between 1.1 and 1.8 times the corresponding cross-sectional dimensions of the electronic component (1) on the connecting layer (4).

3. The method according to claim 1 or 2, wherein: A flexible layer of thermoplastic material (TPM3) is applied over the component and the connection layer and heated to form a cover layer (8), wherein the cover layer is inclined to form a gradual decrease in the thickness of the overall stack from the electronic component outwards.

4. The method according to claim 1 or 2, wherein: At least two of the thermoplastic materials are formed from compositions that exhibit overplasticization conditions.

5. The method according to claim 1 or 2, wherein: The conductive tracks (2) are arranged in parallel directions to form parallel tracks.

6. The method according to claim 1 or 2, wherein: The thermosetting material (TSM1) includes a conductive adhesive material.

7. The method according to claim 1 or 2, wherein: The method includes connecting the flexible substrate to a carrier (20).

8. An assembly (30) of an electronic component (1) connected to at least one conductive track (2) on a flexible substrate (3), the flexible substrate being formed from a thermoplastic substrate material (TPM2), the assembly comprising: a connecting layer (4) on the conductive track (2), wherein the connecting layer (4) is formed by a sheet comprising a thermoplastic material (TPM1), the thermoplastic material being a material different from the substrate material (TPM2), wherein the connecting layer (4) has at least one cutout (5), wherein the at least one cutout (5) is aligned to at least partially overlap the conductive track (2); - a cured thermosetting material (TSM1) filling said cutout (5), wherein said thermosetting material (TSM1) is electrically conductive; - wherein the electronic component (1) is arranged on top of the connection layer (4), wherein the contact points (7) of the electronic component (1) are aligned in contact with the thermosetting material (TSM1) filling the cutout (5); - wherein the mechanical connection (M) between the electronic component (1) and the flexible substrate and / or the conductive track on the flexible substrate is formed by plastic deformation of the connecting layer, and wherein the electrical connection (E) between the contact point (7) of the electronic component (1) and the conductive track (2) on the flexible substrate (3) is formed by the cured thermosetting material (TSM1).

9. The assembly according to claim 8, wherein: The assembly comprises a plurality of laterally spaced apart electronic components (1) which are electrically connected to one another via one or more conductive tracks (2).

10. An assembly according to claim 8 or 9, wherein The electronic component is a printed circuit board (10).

11. An assembly according to claim 8 or 9, wherein: The conductive track (2) electrically connects the electronic component (1) to the receiving pad (12).

12. An assembly according to claim 8 or 9, wherein: The flexible substrate (3) is permanently connected to a carrier (20).

13. The assembly according to claim 8 or 9 further comprises a covering layer (8) formed by applying a flexible layer of thermoplastic material (TPM3) onto the electronic component (1) and the connecting layer (4) and heating the covering layer, wherein the covering layer is inclined to form a gradual decrease in the thickness of the total stack from the electronic component outward.

14. The assembly of claim 13, wherein: A protective layer (9) is provided on one or more of the electronic component (1), the cover layer (8), the conductive track (2), the flexible substrate (3) and the carrier (20) to protect the assembly from external damage.

15. The assembly of claim 14, wherein: One or more of the thermoplastic material (TPM1) contained in the connecting layer (4), the thermoplastic material (TPM2) contained in the flexible substrate (3), the thermoplastic material (TPM3) contained in the layer forming the covering layer (8), the thermoplastic material contained in the protective layer (9) and the thermoplastic material in the intermediate adhesive layer are formed from a composition containing thermoplastic polyurethane (TPU).

16. An assembly according to claim 8 or 9, wherein: The glass transition temperature of the substrate material (TPM2) differs from the glass transition temperature of the thermoplastic material (TPM1) contained in the connecting layer by at least 5 degrees Celsius.

17. A garment (40) comprising an assembly according to any one of claims 8 to 16.

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