Electronic systems and methods for using electronic systems in industrial manufacturing

Abstract

The present invention relates to an electronic system comprising: at least one substrate having at least one conductive strip on at least one surface; at least one anisotropically conductive adhesive film disposed on the surface of the substrate; and at least one electronic component having at least one contact surface and being placed flat on the adhesive film by means of the contact surface, wherein the adhesive film comprises at least one crosslinking agent, the crosslinking agent being viscous in an uncrosslinked or partially crosslinked state and losing its viscousness in a crosslinked state.

Description

[Technical Field]

[0001] This invention relates to an electronic system and a method for manufacturing electronic systems in industrial applications. [Previous Technology]

[0002] Anisotropic conductive adhesive films are known, for example, from US 2007 / 0116961 A1 and are commonly used to connect two substrates and conductor strips to each other to create a laminate, wherein the individual conductor strips can be connected to each other without short circuits by means of anisotropic conductive adhesive films.

[0003] Furthermore, as is known in the prior art, in order to mount multiple electronic components, such as surface-mount devices, onto a circuit board, a conductive liquid adhesive is applied individually to each electronic component on the circuit board, and then the electronic component is pressed onto the still liquid adhesive using a pick-and-place machine. Typically, the circuit board is finally guided through a heating facility, such as a reflow oven, where the liquid adhesive hardens. This method is disclosed, for example, in DE 101 40 661 C1. Alternatively, the above pick-and-place method can also be implemented using solder paste or solder instead of liquid adhesive.

[0004] There are increasingly more applications that involve placing and contacting a large number of electronic components on a circuit board, such as in the manufacture of LED displays. The classic pick-and-place method of individually placing electronic components is very costly for these applications because the complexity of the method is proportional to the number of electronic components. Correspondingly, there is a need for an electronic system that can bring electronic components into contact via conductive lines on a substrate in a manner that is scalable and does not involve disadvantages in manufacturing cost or contact quality. [Summary of the Invention]

[0005] The object of the present invention is, in particular but not only, to provide an electronic system or a method for manufacturing an electronic system, which has improved characteristics in terms of the fixation and electrical contact of electronic components on a substrate. The above object is achieved by the features of embodiments of the present invention, and advantageous designs and improvements of the present invention can be derived from embodiments of the present invention.

[0006] An electronic system according to the present invention includes: at least one substrate, the substrate including at least one conductive strip on at least one surface, at least one non-isotropically conductive adhesive film disposed on the surface of the substrate, and at least one electronic component including at least one contact surface and resting flat on the adhesive film by means of the contact surface, wherein the adhesive film includes at least one crosslinking agent, is viscous in an uncrosslinked or partially crosslinked state and loses its viscousness in a crosslinked state.

[0007] Furthermore, in the method for industrial manufacturing of electronic systems according to the present invention, an adhesive film is provided by means of an adhesive film-storage roller, a substrate is transported along the production line, the adhesive film is continuously unwound and applied to the substrate to connect electronic components to the substrate.

[0008] Thus, an electronic system with any number of electronic components can be provided, the manufacture of which avoids the disadvantages of the classic pick-and-place method. Advantageously, instead of multiple process steps for coating each adhesive point, the adhesive film can be completely applied in a single process step. Particularly advantageously, electronic components can be pressed into the adhesive film in its uncrosslinked or partially crosslinked state, thereby ensuring complete wetting of the electronic components and firm fixation after the adhesive film has crosslinked.

[0009] The electronic system may include any number of substrates, adhesive films, and electronic components. In the case where the electronic system includes multiple substrates and adhesive films, the substrates and adhesive films may have the same or different dimensions. Furthermore, the substrates may, for example, be stacked one on top of the other, wherein the adhesive film is disposed not only between the substrates but also on at least one outer surface of the substrates, and connects the electronic components to conductive strips disposed on the outer surface.

[0010] The substrate can comprise any electrically insulating material. In this context, "electrically insulating" should be understood as having a resistivity of at least 10¹¹ Ωmm² / m at 25°C. For example, the substrate can be configured as a glass plate, a plastic plate, or a cellulose plate. The substrate is preferably configured as a circuit board. The substrate can be configured as a single-layer circuit board or a multi-layer circuit board. The substrate can be made of a rigid, brittle material, such as fiber-reinforced plastic or cardboard. Preferably, the substrate is made of a flexible, stretchable material, such as a thin film, wherein the thin film may include plastic and / or cellulose.

[0011] The substrate can include any number of conductive strips. Preferably, the substrate includes at least one pair of conductive strips that provide power to electrical components. The conductive strips can partially or completely penetrate the substrate. Preferably, the conductive strips constitute a coating on the surface of the substrate. The conductive strips can be coated onto the surface of the substrate by any coating or printing method, such as blade coating, slot coating, curtain coating, gravure printing, offset printing, flexographic printing, inkjet printing, screen printing, LAM printing, or stereolithography.

[0012] Preferably, the substrate does not include notches, protrusions, or recesses, at least within the surface to which it is mounted. "Surface to be mounted" should be understood as the smallest possible connected portion of the substrate surface, which, in a top view of the electronic system, includes all electronic components of the electronic system. In this context, a top view is understood as a view of the electronic system from above or below, in which components of the electronic system that may be obscured by electronic components are not shown. The substrate may include edges, notches, protrusions, and / or recesses outside the surface to which it is mounted, which may be designed, for example, to secure the electronic system. The substrate can have any shape, and such shape can be arbitrarily curved. Preferably, the substrate is layered. "Layered" should be understood as the object not having bending or wrinkling in a static state, and the width and length of the object being at least 500%, advantageously 750%, and particularly advantageously at least 1000% of the height of the object. In this context, the "static state" of an object should be understood as a state in which the object lies flat on a flat surface and is not subjected to deformation, such as bending, stretching, or wrinkling.

[0013] Preferably, in this method, the substrate is provided by means of a substrate-storage roller. Preferably, multiple substrates are transported along the production line. Particularly preferably, the substrate is part of a substrate-strip that is wound onto the core of the substrate-storage roller and continuously unwound. The substrate-strip may include a removable carrier that is removed after the adhesive film is applied and crosslinked and can be wound onto another waste roller. Alternatively, the substrate-strip may be configured as a single layer from which the various electronic systems are cut or punched after the adhesive film is applied and crosslinked.

[0014] Preferably, the adhesive membrane is layered. The adhesive membrane can have any shape in a top view when at rest, such as triangular, rectangular or oval.

[0015] The phrase "non-isotropically conductive" in the context of an adhesive film should be understood as meaning that the adhesive film is conductive on its main side perpendicular to the main side, and substantially electrically insulating on its parallel side. The phrase "substantially" electrically insulating on its parallel side in this context should be understood as meaning that the adhesive film is electrically insulating to at least the extent that the distance between adjacent contact surfaces parallel to the main side of the adhesive film is sufficiently large to avoid short circuits. The minimum distance between adjacent contact surfaces that remains electrically insulating from each other is also called the "rastermaß" or "pitch". The phrase "conductive" in this context should be understood as meaning that the material or component has a resistivity of up to 100 Ωmm² / m at 25°C.

[0016] The adhesive film includes at least one conductive adhesive. The adhesive may include at least one conductive polymer. For example, the adhesive may be a PEDOT:PSS-based adhesive. Preferably, the adhesive includes conductive particles. The conductive particles may be made of, for example, metal, conductive polymer, or carbon, or may be formed as a body of a metal coating made of glass, plastic, or ceramic. Particularly preferably, the adhesive film has a reduced layer thickness in the contact area, wherein the contact surface is in direct contact with the conductive particles. This can be achieved by pressing the electronic component in the uncrosslinked or partially crosslinked state of the adhesive film, because the adhesive film has sufficient viscosity during its tacky period to leak out below the contact surface upon pressing.

[0017] The conductive particles can be arranged in a chain oriented perpendicular to the main side of the adhesive film. This arrangement of the conductive particles can be achieved, for example, by orienting the conductive particles using an electromagnetic field. Alternatively, the adhesive film may include conductive particles with an average diameter greater than the thickness of the adhesive film. Preferably, the conductive particles are dispersed in a conductive adhesive.

[0018] The adhesive film may include any type of conductive adhesive, such as acrylate adhesive, epoxy resin adhesive, polyurethane adhesive, rubber adhesive and / or silicone resin adhesive, which are conductive.

[0019] The adhesive film may include any other substances and additives besides the conductive adhesive, such as anti-aging agents, fillers, thermally conductive particles, thermally insulating particles, crosslinking agents, catalysts, thickeners and / or tackifiers.

[0020] The adhesive film may be configured as part of a one-sided or two-sided adhesive tape. The one-sided or two-sided adhesive tape includes at least one anisotropically conductive carrier. The carrier may include at least one electrically insulating material, such as plastic or cellulose, the electrically insulating material including a plurality of recesses filled with a conductive material, such as metal or carbon. Preferably, the adhesive film is configured as a transfer film. "Transfer film" should be understood as an adhesive film that exists as part of a transfer adhesive tape in an unapplied state. The one-sided or two-sided adhesive tape or transfer adhesive tape may include a removable carrier, also referred to as a "release liner," covering the outer surface of the adhesive film. When a single-sided or double-sided adhesive tape or transfer adhesive tape exists as a wound adhesive tape, it may include only one removable carrier. Alternatively, the single-sided or double-sided adhesive tape or transfer adhesive tape may exist as a planar adhesive tape, such as a stamped piece, and include two removable carriers disposed on opposite outer sides of the adhesive film. For example, the removable carrier may be composed of silicone cellulose.

[0021] The term "adhesive film" should be understood as meaning that the adhesive film is designed to form a non-covalent adhesive bond with the mating material by means of mere application and / or manual pressing. Preferably, the adhesive film has a glass transition temperature of up to -10°C in its uncrosslinked or partially crosslinked state.

[0022] "Uncrosslinked or partially crosslinked state" should be understood as a state in which the polymers of the adhesive film are not crosslinked or only partially crosslinked with each other. The uncrosslinked or partially crosslinked state can exist under predefined conditions, such as a specific temperature. The uncrosslinked or partially crosslinked state can be maintained for any period of time and is different from the temporary state. The temporary state, for example, may exist only at specific moments during the crosslinking reaction. For example, the adhesive film in the uncrosslinked or partially crosslinked state can exist as an adhesive film and can be permanently viscous; alternatively, the adhesive film in the uncrosslinked or partially crosslinked state can be configured as a molten adhesive and become viscous only by melting. In the crosslinked state, the polymers form a polymer network. The crosslinking of polymers is different from polymerization, in which monomers are linked to form a polymer. The crosslinking agent is a molecule comprising at least two functional groups that can react with the functional groups of the polymer, and the polymers are linked together at the aforementioned functional groups after the crosslinking reaction. The crosslinking agent can be homobifunctional or heterobifunctional. Homologous bifunctional crosslinkers comprise multiple identical functional groups, while heterologous bifunctional crosslinkers comprise functional groups that are distinct from each other. Crosslinkers can, for example, comprise functional groups based on amines, amides, thiols, hydroxyl groups, carboxylates, aldehydes, organophosphates, maleimides, NHS-esters, thiol groups, acids, alcohols, isocyanates, and halides. "Based on" in this context should be understood to include all derivatives that can be associated with the above-mentioned groups and are known to those skilled in the art as suitable for the manufacture of adhesives. Crosslinkers can be configured as activated crosslinkers, and the crosslinking reaction is initiated immediately upon contact with the polymer. Alternatively, crosslinkers can be configured as deactivated crosslinkers and are present, for example, in the form of particles or powders that melt at a predefined temperature and release the crosslinker.

[0023] The adhesive film is provided by means of an adhesive film-storage roller, which should be understood as being part of an adhesive film-tape wound onto the core of the adhesive film-storage roller. Preferably, the adhesive film-tape includes a plurality of adhesive films. The adhesive film-tape may include a removable carrier that covers the outer surface of the adhesive film in an unapplied state. Preferably, the adhesive film-tape includes a matrix layer that includes gaps in which one of the adhesive films is disposed. In the case where the adhesive film-tape includes a removable carrier and a matrix layer, the matrix layer is removed and wound onto a waste roller between unwinding and applying the adhesive film to the substrate, and the removable carrier is removed and wound onto another waste roller after application to the substrate. The process of removing the matrix layer is also referred to as "entgittern". The adhesive film-storage roller can be unwound by moving forward on the production line or integrated into a known pick-and-place device, in which a robot removes the adhesive film from the adhesive film-storage roller and applies it to the substrate. Integrating the adhesive film into a known pick-and-place device has the advantage that it does not require replacing existing production facilities used for manufacturing electronic systems, but only needs to be adapted to the new application process.

[0024] The electronic component includes at least one contact portion disposed above a conductor strip and electrically connected to the conductor strip via an adhesive film. Preferably, the electronic component includes at least a pair of contacts electrically connected to a pair of conductor strips to power the electronic component. The contact surface can be understood as the surface of the contact portion facing the adhesive film. The electronic component may include any type of contact portion, for example, the electronic component may include: at least one lateral terminal, as present, for example in SOD and SOT components; opposing contact surfaces, as present in multilayer capacitors; or protruding spherical contacts, also referred to as "ball grid arrays". The contact portion can protrude from the housing of the electronic component. Preferably, the contact portion is flush with the housing of the electronic component.

[0025] The electronic system may include other components and parts conforming to standards for use in the electronic system, such as encapsulation elements used to protect electronic components from moisture. The electronic system may include adhesives not intended to fix electronic components, but rather to provide electrical insulation for the electronic system, fixing it to an object to which the electronic system is to be mounted, or fixing encapsulation elements to a substrate. The adhesive may be configured as a liquid adhesive or other adhesive film. Furthermore, the electronic system may also include solder and / or solder paste, which, for example, can fix connectors to the substrate and can contact lead wires. The adhesive film may extend beyond the surface of the substrate to which it is mounted. For example, the extended area of ​​the adhesive film may be used to fix encapsulation elements to the substrate or to fold to encapsulate electronic components.

[0026] In another embodiment of the invention, the substrate is configured as a flexible circuit board and the electronic system is reversibly deformable. Preferably, the electronic components are configured as flexible electronic components, particularly preferably coated components. "Coated components" in this context should be understood as components comprising at least one substrate and at least one coating, wherein the coating is manufactured by applying electronic functional materials in layers onto the substrate, the electronic functional materials being in a liquid or paste form prior to the coating. Coated components may include any number of components coated onto the substrate. Coated components can be coated onto the surface of the substrate using any coating or printing method, such as blade coating, slot coating, curtain coating, gravure printing, offset printing, flexographic printing, inkjet printing, screen printing, LAM printing, or stereolithography. Thus, a flexible electronic system is provided that can accommodate non-planar surfaces, thereby enabling a wide range of possible applications.

[0027] In another embodiment of the present invention, the electronic component is configured as a surface-mount device (SMD). In this context, "surface-mount device" should be understood as a device that, unlike THT and THD devices, does not include wire terminals or other connecting elements, but only contacts the conductor strip via contact portions. The coated component is a surface-mount device. Particularly preferred is that the electronic component has dimensions conforming to JEDEC standards for surface-mount devices. The electronic component can be configured as an active or passive component. For example, electronic components can be configured as switches, relays, resonators, oscillators, filters, sensors such as pressure sensors, light sensors, temperature sensors, humidity sensors or resistance sensors, dispensing pumps, microfluidic systems, resistors, capacitors, coils, transformers, magnets, radiation sources, energy sources such as fuel cells and / or solar cells, Peltier elements, diodes, rectifiers, transistors, piezoelectric elements, data storage elements, processors, wafer sets, semiconductors, optical waveguides, motors, audio elements such as speakers, display elements such as LCD components, connection components such as flat cables and / or energy storage devices such as batteries.

[0028] In another design embodiment of the present invention, the electronic component has a contour surface in a top view of the electronic system, the area of ​​which is at most 25 mm². The contour surface of the electronic component includes all functional components of the electronic component. "Functional components" should be understood, for example, as housings, metal wires, contacts, and conductors, but without a protruding substrate. In electronic components that are laminated to a common substrate and connected via conductor strips, the substrate and conductor strips do not form part of the contour surface. For example, the electronic component can be configured as a Mini LED or a micro LED. Until now, electronic components of this size have only been connected by liquid adhesives, because the smaller the adhesive surface, the higher the shear force acting on the adhesive. However, it has been surprisingly found that the above-mentioned shear force can also be compensated by combining pressing the electronic component during the adhesive film's tackiness with a firm fixation after the adhesive film has cross-linked.

[0029] In another embodiment of the present invention, the crosslinking agent is configured as a radiation-activated crosslinking agent, and the adhesive film comprises 0.1% to 20% by weight, preferably 1% to 10% by weight, and particularly preferably 2% to 7% by weight of the crosslinking agent, and 10% to 90% by weight, preferably 20% to 80% by weight, and particularly preferably 30% to 70% by weight of at least one resin. The crosslinking agent may be configured as a free radical initiator. For example, the crosslinking agent may include benzoyl peroxide, persulfate, bis(2-ethylhexyl) peroxydicarbonate, or methyl ethyl ketone peroxide. Preferably, the crosslinking agent is configured as a cationic or anionic initiator. For example, the crosslinking agent may include lithium organic compounds, Grignard compounds, Lewis acids, Brønsted acids, onium salts, ferrocene salts, thioxanthate salts, pyridinium salts, piperan salts, and / or thiapiperanthate salts. The resin can be, for example, a phenolic resin, an epoxy resin, a polyacrylate resin, or a polyamide resin. Preferably, the resin is a combination of an aromatic epoxy resin and an alicyclic epoxy resin. Furthermore, the adhesive film may include at least one film-forming agent, comprising 1% to 40% by weight, preferably 10% to 30% by weight. Thus, an adhesive film can be provided that is tacky in its uncrosslinked state and loses its tackiness after irradiation, thereby enabling strong mechanical fixation of electronic components.

[0030] In another embodiment of the present invention, the crosslinking agent is configured as a heat-activated crosslinking agent, and the adhesive film comprises 0.1 wt% to 20 wt%, preferably 5 wt% to 18 wt%, and particularly preferably 8 wt% to 15 wt% of the crosslinking agent and 40 wt% to 98 wt%, preferably 45 wt% to 90 wt%, and particularly preferably 50 wt% to 70 wt% of the thermoplastic polymer, wherein the activation temperature of the crosslinking agent is at least 10°C higher than the melting temperature of the thermoplastic polymer. The crosslinking agent may be configured as a free radical initiator. For example, the crosslinking agent may include benzoyl peroxide, persulfate, bis(2-ethylhexyl) peroxydicarbonate, or methyl ethyl ketone peroxide. Preferably, the crosslinking agent comprises at least one polyisocyanate and / or at least one polyol. Thermoplastic polymers can be, for example, polyamide, polyoxymethylene (POM homopolymer or POM copolymer), polyethylene terephthalate, polybutylene terephthalate, polytetrafluoroethylene, polypropylene (isotactic or syndiotactic), polyethylene, or polyurethane. Furthermore, thermoplastic polymers can be crystalline polymers that do not include amorphous regions or partially crystalline polymers that include both crystalline and amorphous regions. Thus, adhesive films can be provided that are viscous in an uncrosslinked state at temperatures between the melting temperature and the activation temperature, and lose their viscousness upon heating above the activation temperature, thereby achieving strong mechanical fixation of electronic components.

[0031] In another embodiment of the present invention, the adhesive film includes 0.1% to 20% by weight, preferably 10% to 20% by weight, of a first crosslinking agent and 0.1% to 20% by weight, preferably 0.5% to 10% by weight, and particularly preferably 1% to 5% by weight, of a second crosslinking agent. The first and second crosslinking agents are thermally activated crosslinking agents with different activation temperatures, radiation-activated crosslinking agents with different absorption spectra, or a combination of thermally activated and radiation-activated crosslinking agents. The adhesive film is viscous after the first crosslinking by the first crosslinking agent and loses this viscousness after the second crosslinking by the second crosslinking agent. The first and second crosslinking agents can be, for example, free radical initiators, cationic initiators, or anionic initiators. Preferably, the first crosslinking agent and the second crosslinking agent are thermally activated crosslinking agents, wherein the first crosslinking agent has an activation temperature of up to 25°C, preferably up to 10°C, and particularly preferably up to 5°C, and the second crosslinking agent has an activation temperature of at least 35°C, preferably at least 50°C, and particularly preferably at least 60°C. The first crosslinking agent can be an amine crosslinking agent, such as an aliphatic amine, aliphatic polyamine, or phenolic amine, or a amide crosslinking agent, such as phenolic amine, while the second crosslinking agent can be an amide crosslinking agent, such as dicyandiamide. Thus, an adhesive film can be provided, which may be non-adhesive in its uncrosslinked state, but exists in a partially crosslinked state and is viscous after the first crosslinking, and loses the aforementioned viscousness after the second crosslinking, thereby achieving strong mechanical fixation of electronic components.

[0032] In another embodiment of the present invention, the adhesive film has a thickness of 1 μm to 1000 μm, preferably 5 μm to 500 μm, and particularly preferably 5 μm to 100 μm, an average diameter of 1 μm to 350 μm, preferably 5 μm to 200 μm, and conductive particles with a pitch of 2 μm to 1000 μm, preferably 5 μm to 500 μm, and particularly preferably 5 μm to 100 μm. The corresponding pitch is related to the ratio of the adhesive film thickness to the size and density of the conductive particles. Thus, the pitch can be matched to the corresponding electronic components. For example, different adhesive films can be provided, each designed according to JEDEC standards for surface-mount devices of different sizes.

[0033] In another embodiment of the present invention, the electronic system includes a plurality of electronic components, which are placed flat on the adhesive film with spacing between them. The plurality of electronic components can include any number of electronic components, preferably at least 5, and more preferably at least 10. The electronic components can be identical or different from each other. Thus, the flexibility and scalability of the electronic system can be fully utilized.

[0034] Electronic components can cover any proportion of the substrate surface. In another embodiment of the invention, the surface of the substrate to be mounted occupies at least 40%, preferably at least 60%, and particularly preferably at least 80% of the substrate surface. For example, the electronic system can be configured as a display element, and the electronic components can be configured as LEDs, Mini-LEDs, or micro-LEDs. Thus, by covering almost the entire surface with an adhesive film and fixing and contacting a large number of electronic components with the adhesive film, the advantages of the electronic system and the method according to the invention can be fully utilized.

[0035] The arrangement of electronic components on the substrate can be arbitrary. In another embodiment of the invention, the electronic components are arranged in a pattern in which adjacent electronic components have the same spacing between them. Preferably, the electronic components are arranged in a pattern in which they collectively form a geometric shape, such as a quadrilateral, triangle, or oval, in a top view. Particularly preferred, the electronic components are arranged in a matrix. Thus, the adhesive film can be cut according to the corresponding electronic components in a simple and efficient manner.

[0036] In a method for industrial manufacturing of electronic systems, electronic components can be placed onto an applied adhesive film by means of a robot. In another embodiment of the invention, the electronic components are already set on the adhesive film before application and are provided by means of an adhesive film-storage roller. Preferably, the adhesive film-storage roller includes electronic components of a plurality of electronic systems, which are arranged along the length of the adhesive film-strip. If the adhesive film-strip includes a removable carrier, the removable carrier may include a plurality of pouches, each of which houses an electronic component of one of the electronic systems. The electronic components are secured to the adhesive film while it is in an uncrosslinked or partially crosslinked state, wherein the adhesive film transitions to a crosslinked state and loses its adhesiveness after application. Thus, the manufacturing of electronic systems can be achieved without the use of robots and pick-and-place processes, thereby reducing the manufacturing time and complexity of the facilities used to perform the manufacturing method from dependence on the number of electronic components to be secured. Advantageously, facilities implementing this method can be equipped with only separately compatible adhesive film-storage rollers for manufacturing different electronic systems, thereby avoiding costly modifications or reprogramming.

Implementation Method

[0043] FIG1 shows a top view of the electronic system 10. The electronic system 10 is configured as a display element. The electronic system 10 includes a substrate 12. The substrate 12 is configured as a flexible circuit board. Alternatively, the substrate 12 may also be configured as a rigid circuit board. The substrate 12 includes a plurality of conductive strips 26 disposed on the surface of the substrate 12. The conductive strips 26 are configured as printed conductive strips.

[0044] The electronic system 10 includes an anisotropically conductive adhesive film 16. The adhesive film 16 is disposed on the surface of the substrate 12. The adhesive film 16 is configured as a transfer film. Alternatively, the adhesive film 16 may also be configured as a one-sided or two-sided adhesive tape. When the adhesive film 16 is in the applied state, the removable carrier (not shown) of the transfer adhesive tape has been removed. The adhesive film 16 is placed on the surface of the substrate 12.

[0045] The adhesive film 16 has a thickness of 500 μm. The adhesive film 16 includes conductive particles with an average diameter of approximately 175 μm. The adhesive film 16 has a pitch of 500 μm.

[0046] The adhesive film 16 is viscous in the uncrosslinked or partially crosslinked state, but loses its viscousness in the crosslinked state.

[0047] The adhesive film 16 may include, for example, the following components (Example 1): substance Quantity [weight %] Film-forming agent 8.8 Aromatic epoxy resin 54.4 Epoxy polyether compounds 9.6 polyethylene glycol 5.6 Cationic initiators (onium salts) 1.6 conductive particles 20

[0048] Alternatively, the adhesive film 16 may include the following components (Example 2): substance Quantity [weight %] Film-forming agent 1.4 Crystalline polyurethane 54.5 Free radical initiators (polyisocyanates) 11.5 conductive particles 32.6

[0049] The crystalline polyurethane has a melting temperature of 50°C. The free radical initiator has an activation temperature of 100°C.

[0050] Alternatively, the adhesive film 16 may include the following components (Example 3): substance Quantity [weight %] Epoxy resin 68.8 Amine crosslinking agent 4.5 amide crosslinking agent 3.8 catalyst 1.9 silica 1 conductive particles 20

[0051] The amine crosslinking agent has an activation temperature of 5°C. The amide crosslinking agent has an activation temperature of 100°C.

[0052] The electronic system 10 includes a plurality of electronic components 14. Each electronic component 14 includes two contact portions (not shown), each contact portion including a contact surface. The electronic components 14 are laid flat on the adhesive film 16 by means of the contact surfaces. The electronic components 14 are identically constructed. Alternatively, the electronic components 14 may be differently constructed. The electronic components 14 are configured as coated components. By combining the flexible circuit board and the coated components, the electronic system 10 can be reversibly deformed and can also be fitted to non-planar surfaces. The electronic components 14 are configured as coated LEDs, each having a contour surface in top view, the area of ​​which is approximately 1 mm2. In this example, each coated LED includes its own substrate; alternatively, all LEDs may be coated onto a common substrate.

[0053] The contact portion of the electronic component 14 provides power to the electronic component. The wire strips 26 are arranged in pairs, wherein each pair of wire strips 26 provides power to a row of electronic components 14.

[0054] The surface of the substrate 12 to be mounted occupies approximately 90% of the surface of the substrate 12. The electronic components 14 are arranged in a matrix.

[0055] Figure 2 shows a schematic flowchart of a method for manufacturing an electronic system 10 in an industrial setting. Figure 3 shows the facilities used to implement the method. In transport step 100, a substrate-belt 18 comprising a plurality of substrates 12 is transported along production line 32. The substrate-belt 18 is unwound from a substrate-storage roller (not shown), or alternatively, the substrates 12 can be stored in a container (not shown) of a substrate supplier in a folded manner and can be pulled out from an opening in the substrate supplier.

[0056] The electronic component 14 was placed on the adhesive film 16 before the adhesive film 16 was applied. In Example 1, the adhesive film 16 was in an uncrosslinked state at this time, and in this uncrosslinked state, the adhesive film 16 was viscous. In Example 2, the adhesive film 16 was transformed to an uncrosslinked state by heating when the electronic component 16 was placed on the adhesive film 16, and after cooling and being wound onto the adhesive film-storage roller, it no longer had any viscous properties. In Example 3, the adhesive film 16 was in a partially crosslinked state at this time, and in this partially crosslinked state, the adhesive film 16 was viscous.

[0057] The adhesive film 16 is provided by means of an adhesive film storage roller. In the application step 110, the adhesive film-strip 20 is unwound from the adhesive film storage roller 28. The adhesive film-strip 20 includes a removable carrier 24. The adhesive film-strip 20 includes a matrix layer 22. The adhesive film-strip 20 includes a plurality of adhesive films 16 disposed in the gaps of the matrix layer 22. The matrix layer is peeled off and wound onto a waste roller 34. Subsequently, in order to connect the electronic component 14 to the substrate 12, the removable carrier 24 together with the adhesive films 16 is applied to the substrate-strip 18. Subsequently, the removable carrier 24 is removed and wound onto another waste roller 36, such that only the substrate-strip 18, the applied adhesive film 16, and the electronic component 14 disposed on the adhesive film 16 remain on the production line 32. The unwinding and application of the adhesive film-tape 20 is a continuous process, driven solely by the movement of the production line 32. For example, the adhesive film-tape 20 may include edge regions with holes punched at regular intervals, into which pins of the production line 32 engage. Alternatively, the manufactured electronic system 10 may be wound onto a product roller (not shown) at the end of the production line 32, and the unwinding and application of the adhesive film-tape 20 is driven by the rotation of the product roller. After application step 110, the substrate-tape 18, adhesive film 16, and electronic components 14 are guided toward the pressure head 30.

[0058] In the crosslinking step 120, the adhesive film 16 is converted to a crosslinked state by means of the pressure head 30, thereby losing its adhesiveness. The pressure head 30 includes a recess (not shown) whose shape matches the extension of the electronic component 14, thereby allowing it to be pressed and fixed. Alternatively, the pressure head 30 may also be made of a soft, elastic material that adheres to the electronic component 14 and similarly allows the electronic component 14 to be pressed and fixed. For the adhesive film 16 of Example 1, the pressure head 30 additionally includes a radiating unit (not shown) that irradiates the adhesive film 16 when the pressure head 30 presses. For the adhesive film 16 of Example 2 or Example 3, the pressure head 30 is configured as a heated pressure head known in the prior art.

[0059] The crosslinking step 120 can also be performed using a clamping mechanism (not shown) to press the electronic component 14 onto the adhesive film 16. The substrate 12, together with the clamping mechanism, is guided through a radiation source (not shown) in the case of the adhesive film 16 in Example 1, or through a reflow oven (not shown) in the case of the adhesive film 16 in Examples 2 or 3, where the adhesive film 16 is heated to 100°C. The reaction time for the adhesive film 16 to transition to the crosslinked state is approximately 10 seconds. Alternatively, the reaction time may be up to 5 minutes, depending on the components used.

[0060] After crosslinking step 120, the adhesive film 16 is in a crosslinked state and no longer has adhesiveness. The electronic component 14 is firmly connected to the substrate 12 and constitutes the manufactured electronic system 10. Method steps 100, 110 and 120 are performed continuously and simultaneously.

[0061] After the crosslinking step 120, the electronic systems 10 can be immediately separated from each other by cutting or punching at the edges of adjacent substrates 12. Alternatively, the electronic systems 10 can be initially wound onto a product roller (not shown) so that they can be separated later for application. [Simplified Explanation of the Diagram]

[0037] Other advantages will be apparent from the description of the accompanying drawings below.

[0038] Attached diagram:

[0039] FIG1 is a top view showing a schematic diagram of the electronic system according to the present invention.

[0040] Figure 2 shows a schematic flowchart of a method for manufacturing electronic systems for industrial purposes according to the present invention.

[0041] Figure 3 shows a schematic diagram of the facility used to implement the method.

[0042] For clarity, multiple identical objects in the figure are associated with only one element symbol.

Claims

1. An electronic system (10) comprising: At least one substrate (12), the substrate including at least one conductor strip (26) on at least one surface; At least one anisotropically conductive adhesive film (16) disposed on the surface of the substrate (12); and at least one electronic component (14) including at least one contact surface and resting flat on the adhesive film (16) by means of the contact surface, wherein the adhesive film (16) includes at least one crosslinking agent, which is viscous in an uncrosslinked or partially crosslinked state and loses its viscousness in a crosslinked state; wherein the substrate (12) is configured as a flexible circuit board and the electronic system (10) is reversibly deformable; wherein the crosslinking agent is configured as a thermally activated crosslinking agent, and the adhesive film (16) includes 0.1% to 20% by weight of the crosslinking agent and 40% to 98% by weight of the thermoplastic polymer, wherein the activation temperature of the crosslinking agent is at least 10°C higher than the melting temperature of the thermoplastic polymer; the electronic system includes a plurality of electronic components (14) resting flat on the adhesive film (16) spaced apart from each other.

2. The electronic system (10) of claim 1, wherein the aforementioned electronic component (14) is configured as a surface-mount device.

3. The electronic system (10) of claim 1 or 2, wherein in a top view of the electronic system (10), the electronic component has a profile surface with an area of ​​up to 25 mm2.

4. The electronic system (10) of claim 1 or 2, wherein the crosslinking agent is configured as a radiation-activated crosslinking agent, and the adhesive film (16) comprises 0.1% to 20% by weight of the crosslinking agent and 10% to 90% by weight of at least one resin.

5. The electronic system (10) of claim 1 or 2, wherein the adhesive film (16) comprises 0.1% to 10% by weight of a first crosslinking agent and 0.1% to 10% by weight of a second crosslinking agent, wherein the first crosslinking agent and the second crosslinking agent are thermally activated crosslinking agents with different activation temperatures, radiation-activated crosslinking agents with different absorption spectra, or a combination of thermally activated crosslinking agents and radiation-activated crosslinking agents, wherein the adhesive film (16) is viscous after being crosslinked for the first time by the first crosslinking agent, and loses the viscousness after being crosslinked for the second time by the second crosslinking agent.

6. The electronic system (10) of claim 1 or 2, wherein the adhesive film (16) has a layer thickness of 1 μm to 1000 μm and includes conductive particles with an average diameter of 1 μm to 350 μm and a pitch of 2 μm to 1000 μm.

7. The electronic system (10) of claim 1, wherein the surface on which the substrate is mounted occupies at least 40% of the surface of the substrate (12).

8. The electronic system (10) of claim 1, wherein the electronic components (14) are arranged in a pattern selected from a group of geometric shapes or matrices, and adjacent electronic components (14) in the pattern have the same spacing.

9. A method for industrial manufacturing of an electronic system (10) such as any one of claims 1 to 8, wherein the adhesive film (16) is provided by means of an adhesive film-storage roller, the substrate (12) is transported along a production line, and the adhesive film (16) is continuously unwound and applied to the substrate (12) to connect the electronic component (14) to the substrate (12).

10. The method of claim 9, wherein the electronic component (14) has been disposed on the adhesive film (16) before the adhesive film (16) is applied and the electronic component (14) is provided by means of the adhesive film-storage roller.

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