Flexible multilayer electronic structures

Abstract

A method for manufacturing a multilayer structure comprises depositing a coat of graphene ink on a passivation layer; bonding a polymer so-called carrier layer using an adhesive; drying the coat of ink; removing some of the graphene and the passivation layer from a first face without cutting into the polymer carrier layer and while removing the polymer carrier layer and the cut-out zones from the second face; bonding adhesive strips along the longitudinal periphery on each side of the passivation layer and in part of the zones with the cut-out graphene; placing electronic components, electrodes, on a polymer substrate layer; and bonding the passivation layer to the substrate layer with the electronic components in that part of the passivation zones that has the graphene cut out.

Description

[0001] FLEXIBLE MULTILAYER ELECTRONIC STRUCTURES

[0002] TECHNICAL FIELD

[0003] The present invention relates to flexible films comprising electronic components or electronic elements or materials. More particularly, the invention relates to a method of manufacturing a flexible multilayer electronic structure in which an electronic part is mounted on an insulating base and covered with an insulating passivation.

[0004] STATE OF THE ART

[0005] There are heating films comprising an electrothermal layer between two insulating layers. Flexible films comprising electronic components are also known, these films comprising electronic components such as resistors, capacitors, or RF antennas for example. Other flexible films can be used to make batteries. These films often use conductive ink, which must be dried before adding another layer of insulation, for example. Other components may be deposited and bonded and different elements on different layers must be electrically connected to each other, which makes the manufacturing process difficult. One aim of the present invention is to improve such a method, for example by making it faster, among other things.

[0006] SUMMARY OF THE INVENTION

[0007] The aim of the present invention is to define a method for manufacturing different types of flexible multilayer electronic structures which is efficient and easy to produce.

[0008] According to a first aspect, a method for manufacturing a flexible, substantially planar, multi-layer structure is presented. The method comprises the following steps: depositing a graphene ink layer on a polymeric passivation layer, leaving an ink void at a longitudinal periphery of the polymeric passivation layer; bonding a polymeric carrier layer previously treated with a pressure-sensitive adhesive to the polymeric passivation layer; drying the ink layer; removing one or more pieces of graphene by cutting out the graphene areas to be removed and the polymeric passivation layer from a first face without cutting the polymeric carrier layer and by removing the polymeric carrier layer and the cut areas from the second face; bonding adhesive strips along the longitudinal periphery on each side of the polymeric passivation layer and in a portion of the areas with the cut graphene;placing electronic components, electrodes and interconnect on a polymeric substrate layer; and bonding the passivation layer on the substrate layer with the electronic components in the part of the passivation zones with the cut graphene.;

[0009] According to a second aspect, a flexible, substantially planar, multilayer electronic structure is presented, the structure being fabricated by the above-mentioned method.

[0010] SUMMARY DESCRIPTION OF THE DRAWINGS

[0011] The characteristics of the invention will appear more clearly on reading the description of several embodiments given solely by way of example, in no way limiting, with reference to Figure 1, in which the different layers present in an electrothermal structure according to an embodiment described in the present document are visible.

[0012] DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention relates to a method for manufacturing a flexible multilayer electronic structure. The structure is substantially planar, preferably elongate, extending in two dimensions over a length and a width, the length being, preferably, several times greater than the width. The structure is an electronic structure in the sense that it may comprise electronic components or circuits, these circuits or components being either positioned or deposited, or printed by a screen printing process, for example. Depending on the required functionality, these circuits or components may be resistors, capacitors, diodes, inductors, transistors or sensors of various types, for example. According to another embodiment, which may be combined with one or more other embodiments mentioned herein, the structure may comprise an electrothermal material for producing heat or cold.The structure may include a conductive layer comprising conductive traces for bonding the components and / or electrothermal elements together to make one or more electrical circuits. In yet another embodiment, the film, or multilayer structure, may be used to make batteries. In yet another embodiment, such structures may be used to make photovoltaic films.

[0014] The electronic part of the flexible multilayer electronic structures, which are manufacturable according to one embodiment of the present invention, is located on one or more layers between a substrate and a passivation, the substrate and the passivation being electrical insulators, for example a polymer. According to a preferred embodiment, the passivation and the substrate each comprise two layers of the polymer bonded together. The structure is therefore airtight and waterproof, electrically insulating and mechanically resistant to scratches and / or cuts.

[0015] According to one embodiment, the polymer comprises a flexible polymer material, for example polyethylene terephthalate (PET). Other polymers are also possible, for example polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), flexible PVC (PVC-P), polystyrene (PS), polycarbonate (PC), polymethyl methacrylate (PMMA), polyoxymethylene (POM), polyethylene terephthalate (PET), polyester, co-polyester, polyetheretherketone (PEEK), polyamide, in particular polyamide 6 (PA6), polyamide 12 (PA12), polyamide 10, polyamide 610, polyamide 66, polyamide based on aliphatic and cycloaliphatic constituents such as in particular MACM12 or amorphous co-polyamide, preferably based on PA12, or copolymers or mixtures thereof. Flexible multilayer electronic structures consist of a base and a cap.The cap includes the electrothermal layer and the base includes the conductive layer which may include electronics. In one embodiment, the flexible multilayer electronic structures of the present invention may be produced on a production line that prints the electronic portion onto the passivation to make the base. The cap is then attached to a substrate, the base, by glue. In a preferred embodiment, the bonding is achieved by a glue that acts with mechanical pressure, or a "PSA" (pressure sensitive adhesive). A PSA is a type of non-reactive adhesive that forms a bond when pressure is applied to bond the adhesive to a surface.

[0016] According to one embodiment, a passivation layer is unwound from a first main roll. Optionally, this passivation layer can be wound onto a second main roll. The passivation is preferably a polymer, as described above. To promote good adhesion of the layers that will be applied to the passivation, this passivation can, optionally, be pre-treated with plasma.

[0017] Depending on the type of electronic structure to be made, for example a heating film with an electrothermal layer, a photovoltaic layer, or a battery, the structure may contain graphene. This layer can be made by depositing a graphene ink. The ink can be prepared by mixing graphene with resins and / or solvents.

[0018] For an electrothermal ink, for example, the molecular structure of graphene is hexagonal in two dimensions. For a conductive ink, microparticles, or even nanoparticles, of graphene can be used. Graphene nanoparticles can have a size of the order of 1 nm to 100 nm. According to one embodiment, the molecular shape of the nanoparticles can be nanotubes, nanospheres or nanowires of graphene, for example.

[0019] In one embodiment, a planetary mixer is used to ensure good ink homogeneity without air bubbles. A layer of premixed graphene ink is deposited on the passivation, preferably by a slot die process, while the passivation takes place under the head of the slot die. The thickness of this layer can be controlled by controlling the unwinding speed of the polymer. In one embodiment, the ink is stirred or mixed at the same time as it is pumped into the head of the slot die. Pump pressure can also be used to control the thickness of the graphene ink layer. For an electrothermal structure, the graphene does not extend to the edges within the width of the passivation.

[0020] The graphene ink layer is then dried, preferably by a near infrared (NIR) ray (shortwave) drying process, which promotes rapid drying of the ink without damaging the polymer. In one embodiment, drying is done by pulses. The inks dry at 120° for about 10 minutes, which is much faster than other techniques without infrared rays, which can have speeds around 6 m / min for a 60m drying tunnel at 125 degrees for example. With infrared rays, drying can take around one to two seconds over a distance of 0.5m or 1m.

[0021] A carrier layer is applied over the passivation. This layer may be applied before, during, or after the graphene ink layer. The carrier layer may be made of a polymer material. In one embodiment, as shown in FIG. 2, the carrier layer is unwound by a first carrier roller 230 and wound by a second carrier roller 240. This layer may be PET that is prepared with a layer of PSA glue. Pressure may be exerted on the carrier layer and the passivation to bond them together, for example, with a pair of rollers in a roller wringer configuration.

[0022] The graphene layer is generally continuous on the passivation after the inking process described above. It is possible to divide this layer into a plurality of graphene blocks, or other defined designs. To be able to produce determined inking areas on the passivation with defined designs, recesses are made in the graphene. According to a preferred embodiment, the recesses are made with a drum-mounted die-cutter system to separate predefined inking areas by cuts. The cuts are made in the graphene and the polymer layer, up to the carrier layer. By removing the carrier layer, the regions of graphene that have been cut, i.e. the offcuts, remain stuck to the carrier and can be discarded. According to another embodiment, this operation is carried out by laser cutting.

[0023] A second passivation layer is applied with PSA glue.

[0024] To complete the hat, electrodes are placed. Optionally, integrated circuits, sensors, or RFID modules can be placed or printed on the hat, along with electrical connectors, to create the desired electronic circuit. The circuits, modules, or sensors are placed in the hollowed-out areas.

[0025] Finally, PSA adhesive strips or ribbons are placed in a part of each recess and along the passivation on the edges that are devoid of graphene. A PSA adhesive strip or ribbon can then be unrolled and attached to the passivation on the two edges of the structure where there is no graphene. The adhesive ribbon can also be glued in the recessed areas, for example pre-cut with the machine in "label" mode.

[0026] A polymer substrate layer can be prepared with integrated circuits or electrical components or sensors or antennas or RFID chips or other printed circuit boards, as well as electrodes to connect the electronics and / or to connect to the graphene. Like the passivation layer, it is possible to treat the substrate layer with plasma to improve the adhesion of the other layers on top. On this substrate layer there can also be connectors, deposited or printed, for example to connect several structures together. The electrodes and connectors can be formed with a conductive ink as described above. This polymer layer, the base, can be unrolled over the cap and the cap and the base glued together using previously positioned adhesive tapes.

[0027] A second passivation polymer layer, prepared with a PSA adhesive layer, may be bonded to the first passivation layer. Similarly, a second substrate polymer layer, prepared with a PSA adhesive, may be bonded to the first substrate layer. In an embodiment in which the structure comprises one or more RFID chips, the method comprises a testing step which comprises reading the RFID chip.

[0028] The structure can be cut into long pieces containing a given number of graphene blocks.

Claims

DEMANDS 1. Method for manufacturing a flexible, substantially planar, multilayer structure (100), the method comprising: deposition of a graphene ink layer on a polymer passivation layer (120, 121) leaving an ink void on a longitudinal periphery of the polymer passivation layer; bonding of a polymer layer called a carrier layer, previously treated with a pressure-sensitive adhesive, to the polymer passivation layer; drying of the ink layer; removal of one or more pieces of graphene by cutting the graphene areas to be removed and the polymer passivation layer from a first face without cutting the polymer carrier layer and by removing the polymer carrier layer and the cut areas from the second face; bonding of adhesive strips along the longitudinal periphery on each side of the polymer passivation layer and in a part of the areas with the cut graphene;placement of electronic components, electrodes and interconnect on a polymeric substrate layer (110, 111); and bonding of the passivation layer (120, 121) to the substrate layer (110, 111) with the electronic components in the part of the passivation zones with the graphene cut.

2. A manufacturing process according to claim 1, further comprising: increasing the thickness of the substrate by bonding a second polymeric layer of substrate (110); increasing the thickness of the passivation by bonding a second polymeric layer of passivation (120).

3. A method according to any one of the preceding claims, wherein the polymer passivation layer (120, 121) is treated with a plasma.

4. A method according to any one of the preceding claims, wherein the polymeric substrate layer (110, 111) is treated with a plasma.

5. A method according to any one of the preceding claims, wherein the graphene ink is dried by infrared ray treatment.

6. A method according to claim 6, wherein the graphene ink is dried by treatment with short infrared rays.

7. Multilayer structure (100), flexible, substantially planar, manufactured by the process according to any one of the preceding claims.

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