Method for transferring an electronic circuit comprising an encapsulated transducer, transferring device and method for manufacturing the device, and composite obtained after transfer

Abstract

The invention relates to a device (1) designed to transfer an electronic circuit (6) from a mother substrate (2) to a daughter substrate, comprising: a) a mother substrate (2), of area SM, b) a layer L1 (3) of polymer composition c1, of area SL 1, arranged on all or part of the mother substrate (2), and c) at least one electronic circuit (6), of area ST, comprising at least one transducer (60) and optionally one or more conductive tracks, said at least one electronic circuit being arranged on all or part of the layer L1 (3) and adhering to the layer L1, said transducer (6) comprising at least two conductive electrodes separated by an electroactive layer of polymer composition, wherein said layer L1 (3) is removably fastened to the mother substrate (2).

Description

[0001] METHOD FOR TRANSFERRING AN ELECTRONIC CIRCUIT COMPRISING AN ENCAPSULATED TRANSDUCER, TRANSFER DEVICE AND METHOD FOR MANUFACTURING THE DEVICE, AND COMPOSITE OBTAINED AFTER TRANSFER

[0002] Field of invention

[0003] The present invention relates to a method for transferring a mother substrate onto a daughter substrate of an electronic circuit comprising at least one transducer or consisting of a transducer, the transducer(s) being based on an electroactive polymer composition. The invention also relates to a device for carrying out the transfer, as well as the composite obtained after the transfer. The present invention also relates to a method for manufacturing the device for the transfer.

[0004] The present invention makes it possible in particular to fix a transducer, or an electronic circuit comprising at least one transducer, on any type of substrate (daughter substrate). It is particularly interesting for fixing a transducer, or an electronic circuit comprising at least one transducer to a deformable or rough substrate and / or to a bulky and non-mobile substrate, for example a substrate forming part of an existing non-instrumented infrastructure.

[0005] Technical background

[0006] A material is said to be "electroactive" if it exhibits a response (deformation, temperature variation, etc.) when an electric field is applied and / or if a stress (mechanical, thermal, etc.) induces an electrical response within the material.

[0007] A transducer is a device for converting a physical magnitude into an electrical signal or vice versa. An electroactive transducer is usually formed by a composition of electroactive material placed between two electrodes.

[0008] The demand for using electroactive transducers for various applications on various substrates continues to increase. One need is to be able to attach one or more transducers, or a circuit comprising them, to various surfaces, particularly stretchable surfaces or surfaces with a certain roughness. Examples of substrates include human skin, leather, and textiles, and applications include measuring heart rate or respiration. Another need is to be able to attach one or more transducers, or a circuit comprising them, to surfaces of existing, non-instrumented infrastructure. Examples of substrates include composite materials, and applications include measuring the structural condition or deformation of a tank or reactor, a wind turbine blade, or a battery.

[0009] Direct printing methods for organic electronics on irregular surfaces are very difficult, if not impossible, to implement because the absence of a smooth surface and / or the presence of a deformable surface is a source of printing defects and leads to the manufacture of poor quality or even defective transducers. Various attempts have been made to obtain transducers on such surfaces. W02022 / 200934 discloses a composite formed from a stack of a leather substrate, a haptic device comprising a piezoelectric polymer manufactured by screen printing, and a polymer membrane covering it. This patent application describes a method for manufacturing the composite comprising a step of hot pressing the polymer membrane onto the haptic device by applying a pressure between 3 and 4 bars at a temperature of 130 to 160°C for at least 30 seconds.The use of these high temperatures, close to or above the Curie temperature of the piezoelectric polymer for the pressing step, is detrimental to the proper maintenance of piezoelectricity when the piezoelectric polymer must be polarized. In addition, this hot pressing step requires the use of substrates that can withstand temperatures above 100°C or, if this is not the case, lead to degradation of the substrate, which reduces the application possibilities.

[0010] There is therefore a need to provide a device for fixing an electronic circuit comprising, or consisting of, at least one transducer, on any type of substrate (in the present invention daughter substrate). The electronic circuit must be able to be fixed on any type of substrate without damaging the substrate and without damaging the electroactive properties of the transducer.

[0011] Objectives of the invention

[0012] An objective of the invention is to provide a device suitable for transferring an electronic circuit from a mother substrate to a daughter substrate making it possible to fix said electronic circuit on any type of substrate, the transfer having to be able to be implemented without damaging the substrate and without damaging the electroactive properties of the transducer.

[0013] According to at least certain embodiments, another objective of the invention is to propose such a device in which the electronic circuit to be transferred and / or the transferred electronic circuit is protected from attacks from the external environment such as attacks caused by air, humidity, other chemical attacks, such as those from corrosive products or perspiration, or even scratches.

[0014] According to at least some embodiments, another objective of the invention is to provide such a device which is easy to manufacture.

[0015] According to at least certain embodiments, another objective of the invention is to provide such a device which allows a simple and efficient transfer of an electronic circuit from a mother substrate to a daughter substrate.

[0016] Other objectives of the invention, related to the objectives of providing said device, are the provision of a composite formed by the electronic circuit fixed to the daughter substrate, the provision of a method of manufacturing said device, and the provision of a method of transferring said electronic circuit onto a daughter substrate.

[0017] Summary of the invention

[0018] The invention relates according to a first aspect to a device (1), suitable for transferring an electronic circuit (6) from a mother substrate (2) to a daughter substrate, comprising a) a mother substrate (2), of surface SM, b) a layer L1 (3) of polymer composition c1, of surface SLI, arranged on all or part of the mother substrate (2), and c) at least one electronic circuit (6), of surface ST, comprising at least one transducer (60) and optionally one or more conductive tracks (71, 72), said at least one electronic circuit being arranged on all or part of the layer L1 (3) and adhering to the layer L1, said transducer (6) comprising at least two conductive electrodes (61, 62; 66, 67) separated by one or more layers of electroactive polymer composition (63; 68).

[0019] Said layer L1 (3) being fixed to the mother substrate (2) in a removable manner.

[0020] The device (1) optionally comprises a layer L2 (4) of polymer composition c2, arranged on all or part of the free surface of the stack formed by the layer L1 (3) and said at least one electronic circuit (6) and adhering thereto, i.e. adhering to said all or part of the free surface on which it is arranged.

[0021] The device (1) optionally comprises a layer L3 (5) of an adhesive or an adhesive precursor, the layer L3 being arranged on all or part of the free surface of the stack formed by the layer L1 (3), said at least one electronic circuit (6), and where appropriate the layer L2 (4) and adhering thereto, i.e. adhering to said all or part of the free surface on which it is arranged.

[0022] The invention relates according to a second aspect to a composite (11) comprising a) a layer L1 (3) of polymer composition c1, b) at least one electronic circuit (6) comprising at least one transducer (60), and optionally one or more conductive tracks (71, 72), said at least one electronic circuit being arranged on all or part of the layer L1 (3) and adhering to the layer L1, said transducer (6) comprising at least two conductive electrodes (61, 62; 66, 67) separated by one or more layers of electroactive polymer composition (63;68), c) optionally, a layer L2 (4) of polymer composition c2, arranged on all or part of the free surface of the stack formed by the layer L1 (3) and said at least one electronic circuit (6), and adhering thereto, d) a layer L3' (7) of an adhesive, the layer L3' being arranged on all or part of the free surface of the stack formed by the layer L1 (3), said at least one electronic circuit (6), and where appropriate the layer L2 (4) and adhering thereto, and e) a daughter substrate (10), arranged on the layer L3' (7) and adhering thereto.;

[0023] According to certain embodiments of aspects 1 (device) and 2 (composite), the electroactive polymer composition consists essentially of, or consists of, an electroactive fluoropolymer.

[0024] According to certain embodiments of aspects 1 (device) and 2 (composite), the electroactive fluoropolymer comprises repeating units derived from vinylidene fluoride (VDF) and vinylidene trifluoride (TrFE), the molar proportion of the unit derived from TrFE being from 15% to 50% relative to the total number of moles of the units derived from VDF and TrFE.

[0025] According to certain embodiments of aspects 1 (device) and 2 (composite), the electroactive fluoropolymer consists essentially of, or consists of, repeating units derived from vinylidene fluoride (VDF) and vinylidene trifluoride (TrFE), and optionally at least one repeating unit derived from a monomer X, other than vinylidene fluoride, having the formula CX1X2=CX3X4, in which each group X1, X2, X3 and X4 is independently selected from H, Cl, F, Br, I and C1-C3 alkyl groups, which are optionally partially or fully halogenated.

[0026] According to certain embodiments of aspects 1 (device) and 2 (composite), the electroactive fluoropolymer is a P(VDF-TrFE), P(VDF-TrFE-CTFE), or P(VDF-TrFE-CFE), or a mixture thereof.

[0027] According to certain embodiments of aspects 1 (device) and 2 (composite), the composition c1 of the layer L1, and where appropriate the composition c2 of the layer L2, are independently of one another, essentially constituted, or constituted of a polymer comprising more than 40% by weight of a fluorinated monomer and / or of a polymer comprising more than 40% by weight of a repeating unit derived from an acrylic or methacrylic monomer. Advantageously, the composition c1 of the layer L1, and where appropriate the composition c2 of the layer L2, are essentially constituted, or constituted of a P(VDF-TrFE), a P(VDF-TrFE-CTFE), P(VDF-TrFE-CFE), a PVDF, a PMMA or their mixture. According to certain particular embodiments, in which the device or the composite comprise a layer L2, c1 and c2 may be of the same chemical composition.According to certain embodiments of aspects 1 (device) and 2 (composite), the device and / or the composite do not comprise an L2 layer.

[0028] According to certain embodiments of aspects 1 (device) and 2 (composite), the adhesive or adhesive precursor of the optional layer L3, respectively the adhesive of the layer L3', is chosen from water-based adhesives, contact adhesives, 2-component adhesives and sealants, thermosetting adhesives, adhesives and sealants polymerizing under the action of humidity and pressure-sensitive adhesives or self-adhesives.

[0029] According to certain embodiments of aspects 1 (device) and 2 (composite), said at least one transducer (60) is a layered transducer formed by a first electrode layer (61), one or more electroactive composition layers (63) and a second electrode layer (62).

[0030] According to certain embodiments of aspects 1 (device) and 2 (composite), said at least one transducer (60) is an interdigital transducer, formed by two comb electrodes (66, 67) and the layer of electroactive composition (68), the two electrodes and the layer of electroactive composition being arranged in the same plane.

[0031] According to certain embodiments of aspects 1 (device) and 2 (composite), said at least one electronic circuit (6) comprises one or more conductive tracks (71, 72) in electrical contact with one or more of the electrodes (61, 62; 66, 67) of said at least one transducer (60).

[0032] According to certain embodiments of aspects 1 (device) and 2 (composite), said layer L1(3) has a thickness of 1 pm to less than 100 pm, and preferably of 2 pm to 20 pm.

[0033] According to certain embodiments of aspect 1 (device), the mother substrate comprises, consists essentially of, or is made of a non-fluorinated polymer preferably chosen from a polyethylene (PE), a polypropylene (PP), a polyester, such as a poly(ethylene terephthalate) (PET), a poly(butylene terephthalate) (PBT), or a poly(ethylene naphthalate) (PEN), a polyamide or copolyamide, such as a PA 11, a PA 12, a PA 6, a PA 6,6, a PA 6,10, a polyacrylonitrile (PAN), and a mixture thereof. The mother substrate may consist essentially of, or consist of, poly(ethylene terephthalate).

[0034] According to some embodiments of aspect 1 (device), the device does not comprise an L3 layer. In these embodiments, the device may comprise an L2 layer. According to some embodiments of aspect 1 (device), the L1 layer (3) is disposed on all or part of the surface of the mother substrate (2), the L1 layer (3) having a low adhesion with the mother substrate (2), said low adhesion being high enough to avoid any delamination of the mother substrate (2) and the L1 layer (3) at an SM-T surface when a low stress is applied to said device and said low adhesion being low enough to allow adhesive failure at the SM-T surface when a moderate stress is applied to said device; said SM-T surface corresponding to the projection of the ST surface onto the SM surface of the mother substrate (2).

[0035] According to certain embodiments of aspect 1 (device), a layer (8) of a temporary adhesive is interposed between said mother substrate (2) and said layer L1 (3) on all or part of the surface Su. Said temporary adhesive may in particular be a water-soluble adhesive, such as for example polyvinyl alcohol.

[0036] According to certain embodiments of aspect 1 (device), a layer (9) of an anti-adhesive is interposed between said mother substrate (2) and said layer L1(3) on a portion of the surface Su. An anti-adhesive may for example be lecithin. Said layer (9) of anti-adhesive may be interposed between said mother substrate (2) and said layer L1(3) at least on one surface SM-T; said surface SM-T corresponding to the projection of the surface ST onto the surface SM of the mother substrate (2). According to certain embodiments of aspect 2 (composite), the daughter substrate (10) is a stretchable or deformable substrate and / or a substrate having surface irregularities, in particular surface roughness.

[0037] According to certain embodiments of aspect 2 (composite), the daughter substrate (10) is selected from a thermoplastic composite, a thermoset composite, a metal, a metal alloy, a woven or non-woven fabric, a wood, a paper, a plaster, skin and a leather.

[0038] The invention relates, according to a third aspect, to a method of manufacturing a device according to the invention comprising:

[0039] - the supply of said mother substrate;

[0040] - an optional step of treating the SM surface of said mother substrate including the implementation of an adhesive, a temporary adhesive and / or an anti-adhesive;

[0041] - printing on the mother substrate, possibly treated, of said layer L1;

[0042] - printing on layer L1 of said at least one electronic circuit;

[0043] - an optional step of printing said layer L2 on all or part of the free surface of the stack formed by the printed layer L1 and said at least one printed electronic circuit; and, - an optional step of depositing said layer L3 on all or part of the free surface of the stack formed by the printed layer L1, said at least one printed electronic circuit, and where appropriate the printed layer L2.

[0044] According to certain embodiments, the printing of the L1 layer (3), the printing of said at least one electronic circuit (6) and the optional step of printing the L2 layer (4) are implemented, independently of each other, by a method chosen from: centrifugation, spraying or atomization, coating in particular with a bar or a film puller, coating with a slotted head, immersion, roll-to-roll printing, screen printing, flexography, lithography, electrospinning and inkjet printing. According to particular embodiments, the printing of the L1 layer (3), the printing of said at least one electronic circuit (6) and the optional step of printing the L2 layer (4) are implemented by screen printing.

[0045] According to certain embodiments of aspect 3 (method), the method comprises a step of polarizing said at least one printed electronic circuit.

[0046] According to certain embodiments of aspect 2, the daughter substrate (10) is a stretchable or deformable substrate and / or a substrate having surface irregularities and in particular surface roughness.

[0047] According to certain embodiments of aspect 2, the daughter substrate (10) is selected from a thermoplastic composite, a thermoset composite, a metal, a metal alloy, a woven or non-woven fabric, a wood, a paper, a plaster, skin and a leather.

[0048] The invention finally relates, according to a fourth aspect, to a method for transferring a mother substrate onto a daughter substrate of a device comprising i) providing a device according to the invention and a daughter substrate, ii) depositing said device onto said daughter substrate by means of an adhesive, and removing the mother substrate.

[0049] Brief description of the figures

[0050] The invention will be better understood from the presentation of different embodiments illustrated using figures 1 to 15 and commented on in more detail in the detailed description of the invention.

[0051] [Fig.1] represents a front view of a device 1 comprising only the essential elements of the invention, in which the layer L1 is in direct contact with the mother substrate (2);

[0052] [Fig.2] represents a front view of a device 1 comprising a layer L3 (5).

[0053] [Fig.3] represents a front view of a device 1 comprising a layer L2 (4) and a layer L3 (5). [Fig.4] represents a top view of the device 1 according to Figure 1.

[0054] [Fig.5] represents the surfaces SM, SU and ST of the different elements of the device 1 according to Figures 1 and 4.

[0055] [Fig.6] represents the surfaces projected onto the SM surface of the mother substrate 2 of the different elements of the device 1 according to Figures 1 and 4.

[0056] [Fig.7] represents a front view of a device 1, in which a temporary adhesive layer (8) is interposed between the mother substrate (2) and the L1 layer (3).

[0057] [Fig.8] represents a front view of a device 1, in which an anti-adhesive layer (9) is interposed on at least the SM-T surface between the mother substrate (2) and the L1 layer (3).

[0058] |Fig.9] represents a front view of a device 1, in which an anti-adhesive layer (9) is interposed on at least part of the SM-LI surface between the mother substrate (2) and the L1 layer (3).

[0059] [Fig.10] represents a section (perpendicular to the printing plane) of a 60 “layered” transducer.

[0060] [Fig.11] is an exploded perspective view of an electronic circuit (6) comprising a layered transducer 60 of the type shown in Figure 7.

[0061] [Fig.12] is a top view of an electronic circuit (6) comprising layered transducers 60 of the type shown in Figure 7.

[0062] [Fig.13] is a view in the printing plane of an “interdigitated” transducer 60.

[0063] [Fig.14] represents a front view of a composite 11 obtained by transfer onto a daughter substrate 10 of a device according to Figure 1 or according to Figure 2.

[0064] [Fig.15] represents a front view of a composite 11 obtained by transfer onto a daughter substrate 10 of a device according to Figure 3.

[0065] Detailed description of the invention

[0066] The invention is now described in more detail and in a non-limiting manner in the following description.

[0067] Figures 1 to 3 show diagrammatically different modes of implementation of the device (1) according to the invention.

[0068] With reference to Figure 1, a device 1 according to the invention comprises a mother substrate 2, a layer L1 (3) of polymer composition c1, arranged on a part of the mother substrate 2, and an electronic circuit (6) arranged on a part of the layer L1 (3) and adhering to the layer L1. The layer L1 (3) is fixed to the mother substrate 2 in a removable manner. Different modes of removable fixing are presented later in the figures. This structure is particularly advantageous, since it allows for a decorrelation between the printing support (or mother substrate) of the layer L1 and the electronic circuit relative to the final substrate (or daughter substrate). This makes it possible to use the electronic circuit encapsulated by the layer L1 on any type of surface including irregular surfaces (high roughness for example), stretchable substrates (fabrics for example) or those having a radius of curvature for example.Furthermore, advantageously, as will be seen later, the method of transferring such a device does not require a hot pressing step or any other step which could induce degradation of the piezoelectric properties of the electronic circuit and / or degradation of the final substrate (daughter substrate).

[0069] Referring to Figure 2, the device 1 is the same as that of Figure 1, and it further comprises a layer L3 (5) of an adhesive or an adhesive precursor, the layer L3 being arranged on the free surface of the stack formed by the layer L1 (3) and said at least one electronic circuit (6).

[0070] Referring to Figure 3, the device 1 is the same as that of Figure 1, and it further comprises a layer L2 (4) of polymer composition c2, arranged on a part of the free surface of the stack formed by the layer L1 (3) and the electronic circuit (6) and, it further comprises a layer L3 (5) of an adhesive or an adhesive precursor, the layer L3 being arranged on the free surface of the layer L2 (4).

[0071] Figures 4 to 6 represent the different relevant surfaces of the device according to Figure 1.

[0072] Figure 4 is a top view of the device (1) according to Figure 1. With reference to Figure 5, the free surface of the mother substrate (2) before deposition of the L1 layer (3) is the SM surface, the free surface of the L1 layer before deposition of the electronic circuit (6) is the Su surface, and the free surface of the electronic circuit (6) is the ST surface.

[0073] By projecting the ST and Su surfaces onto SM respectively, we can subdivide the SM surface into three distinct surfaces: SMO, SM-U and SM-T.

[0074] We then have: ST = SM-T; Su= SM-T+ SM-U; and SM = SM-T+ SM-U+SMO.

[0075] In the device according to the invention, it is necessary for the mother substrate (2) to have low adhesion at least at the SM-T surface, since once the electronic circuit has been transferred to a daughter substrate, the L1 layer covering the electronic circuit must be able to act as an encapsulant and protect the electronic circuit over its entire surface. This layer has the role of protecting the electronic circuit from humidity, oxygen, chemical attacks and mechanical attacks (shock, scratches). The L1 layer (3) can be fixed to the mother substrate (2) in a removable manner in various ways: the polymer composition c1 of the Su layer can have little affinity with the surface of the mother substrate (2).This is generally the case when the polymer composition c1 of the layer Su is essentially made up of or is made up of a fluorinated polymer and the substrate is essentially made up of, or is made up of, a non-fluorinated polymer chosen from a polyethylene (PE), a polypropylene (PP), a polyester, such as a poly(ethylene terephthalate) (PET), a poly(butylene terephthalate) (PBT), or a poly(ethylene naphthalate) (PEN), a polyamide or copolyamide, such as a PA 11, a PA 12, a PA 6, a PA 6,6, a PA 6,10, a polyacrylonitrile (PAN), and their mixture, and preferably a poly(ethylene terephthalate) (PET).

[0076] Referring to Figure 7, a layer (8) of a temporary adhesive may be interposed between the mother substrate (2) and the L1 layer (3) on all or part of the Su surface, for example on the SM-T surface, OR on the SM-LI surface, OR on the Su surface. Such a temporary adhesive is for example polyvinyl alcohol which is known to dissolve in water.

[0077] Referring to Figures 8 and 9, a layer (9) of an anti-adhesive may be interposed between the mother substrate (2) and the L1 layer (3) on a portion of the Su surface. An anti-adhesive may for example be lecithin.

[0078] Figure 8 represents an embodiment where the anti-adhesive (9) covers at least the SM-T surface. This has the advantage of protecting the surface of the L1 layer (3) covering the electronic circuit once the latter has been transferred to a daughter substrate in order to avoid any risk of deterioration during removal of the mother substrate (2). In this embodiment, the surface of the L1 layer which adheres to the mother substrate is all or part of the SM-LI surface. The adhesion of the part of the L1 layer which adheres to the mother substrate can be weak or strong since in these embodiments, the mother substrate can be removed from the device for example by cutting around the area having good adhesion.

[0079] Figure 9 shows an embodiment where the anti-adhesive (9) at least partially covers the SM-LI surface. This has the advantage of creating a gripping zone to be able to separate the L1 layer (3) from the mother substrate (2). In this embodiment, the adhesion of the L1 layer (3) to the mother substrate must be low over the entire part not comprising anti-adhesive. Figures 10 and 11 show a “layered” transducer (60) formed by the superposition of a first electrode (62), an electroactive polymer composition (63) and a second electrode. Conductive tracks (72) and (71) in electrical contact with said electrodes make it possible to form an electronic circuit 6. A circuit comprising several transducers (60) connected together by conductive tracks (71, 72) is shown in Figure 12.As seen in Figure 11, the layer of electroactive polymer composition (63) advantageously extends beyond the electrodes so as to avoid any accidental short circuit.

[0080] Figure 13 shows an interdigital transducer (60) where the electrodes (66, 67) and the electroactive polymer composition layer are all in the same plane.

[0081] Figure 14 shows a composite (11) comprising a) a layer L1 (3) of polymer composition c1, an electronic circuit (6), said electronic circuit being arranged on a part of the layer L1 (3) and adhering to the layer L1, a layer L3' (7) of an adhesive, the layer L3' being arranged on the free surface of the stack formed by the layer L1 (3) and the electronic circuit (6) and a daughter substrate (10), arranged on the layer L3' (7).

[0082] Figure 14 shows a composite (11) further comprising a layer L2 (4) interposed between the electronic circuit (6) and the layer L3' (7).

[0083] Mother substrate

[0084] The mother substrate may comprise, be essentially made up of, or be made up of a non-fluorinated polymer preferably chosen from a polyethylene (PE), a polypropylene (PP), a polyester, such as a poly(ethylene terephthalate) (PET), a poly(butylene terephthalate) (PBT), or a poly(ethylene naphthalate) (PEN), a polyamide or copolyamide, such as a PA 11, a PA 12, a PA 6, a PA 6,6, a PA 6,10, a polyacrylonitrile (PAN), and a mixture thereof.

[0085] The mother substrate is preferably PET.

[0086] Layers (L1) and (L2)

[0087] The composition c1 of the layer L1, and where appropriate the composition c2 of the layer L2, may, independently of one another, be essentially constituted, be constituted of a polymer comprising more than 40% by weight of a fluorinated monomer and / or of a polymer comprising more than 40% by weight of a repeating unit derived from an acrylic or methacrylic monomer. Advantageously, the composition c1 of the layer L1, and where appropriate the composition c2 of the layer L2, are, independently of one another, essentially constituted, or constituted of a P(VDF-TrFE), a P(VDF-TrFE-CTFE), P(VDF-TrFE-CFE), a PVDF, a PMMA or their mixture.

[0088] These polymers have the advantage of having a good affinity with the polymers of the electroactive composition of the electronic circuit, which makes it possible to generate good adhesion between the L1 layer and the layer of electroactive polymer composition (which generally extends beyond the electrodes), and where appropriate good adhesion between the L2 layer and the layer of electroactive polymer composition (which generally extends beyond the electrodes).

[0089] According to certain particular embodiments, in which the device or the composite comprises a layer L2, c1 and c2 may be of the same chemical composition.

[0090] The L1 layer preferably has a thickness of 1 to less than 100 pm, and preferably of 2 to 20 pm.

[0091] The L2 layer, when present, preferably has a thickness of 1 to less than 100 pm, and preferably 2 to 20 pm.

[0092] Electronic circuit

[0093] The electrodes and / or the conductive tracks may in particular be formed from a conductive polymer composition or a composition based on conductive metals, for example this composition may be a PEDOT:PSS composition (PEDOT = poly(3,4-ethylenedioxythiophene, PSS=poly(styrene sulfonate)), a silver-based composition, for example silver, copper or carbon nanowires, for example graphene. Solutions based on these materials are generally aqueous solutions.

[0094] The electrode layers and / or the conductive tracks preferably have a thickness of between 0.5 and 5 μm, and preferably between 0.8 and 2 μm.

[0095] The layer of electroactive polymer composition preferably has a thickness of between 1 and less than 100 pm, preferably between 2 and 50 pm, and more preferably between 3 and 10 pm.

[0096] The electroactive polymer composition may consist essentially of, or consist of, an electroactive fluoropolymer.

[0097] According to certain preferred embodiments, the electroactive fluoropolymer comprises repeating units derived from vinylidene fluoride (VDF) and vinylidene trifluoride (TrFE), the molar proportion of the unit derived from TrFE being from 15% to 50% relative to the total number of moles of the units derived from VDF and TrFE. Depending on the end uses of the electronic circuit, the electroactive fluoropolymer may consist of, or be made up of, repeating units derived from vinylidene fluoride (VDF) and vinylidene trifluoride (TrFE), and optionally at least one repeating unit derived from a monomer X, other than vinylidene fluoride, having the formula CXiX2=CX3X4, in which each group Xi, X2, X3 and X4 is independently selected from H, Cl, F, Br, I and C1-C3 alkyl groups, which are optionally partially or fully halogenated.

[0098] The electroactive fluoropolymer may be P(VDF-TrFE), P(VDF-TrFE-CTFE), or P(VDF-TrFE-CFE), or a mixture thereof.

[0099] Known good solvents for these polymers are, for example, methyl ethyl ketone (MEK), triethyl phosphate (TEP), cyclohexanone, gamma butyrolactone or ethyl acetate, in which these polymers can be dissolved.

[0100] Adhesive layer

[0101] The adhesive or adhesive precursor of the optional layer L3, respectively the adhesive of the layer L3', can be chosen from water-based adhesives, contact adhesives, 2-component adhesives and sealants, thermosetting adhesives, adhesives and sealants polymerizing under the action of humidity and pressure-sensitive adhesives or self-adhesives.

[0102] Daughter substrate

[0103] The daughter substrate can be of any type and its nature is not limited. This substrate can for example be a plastic substrate, a metal substrate, a stretchable or deformable substrate, a substrate having surface irregularities, for example a surface roughness. For example the daughter substrate can be a plastic substrate, a metal substrate, a fabric (in particular leather, cotton, synthetic fiber, etc.), wood, plaster, human skin, etc.

[0104] The invention also relates to a method for manufacturing a device according to the invention comprising: providing a mother substrate; an optional step of treating the surface SM of said mother substrate including the use of an adhesive, a temporary adhesive and / or an anti-adhesive; printing on the mother substrate, optionally treated, said layer L1; printing on layer L1 said at least one electronic circuit; an optional step of printing said layer L2 on all or part of the free surface of the stack formed by the printed layer L1 and said at least one printed electronic circuit; and, an optional step of depositing said layer L3 on all or part of the free surface of the stack formed by the printed layer L1, said at least one printed electronic circuit, and where appropriate the printed layer L2.

[0105] According to certain embodiments, the printing of the layer L1 (3), the printing of said at least one electronic circuit (6) and the optional step of printing the layer L2 (4), can be implemented, independently of one another by a method chosen from: centrifugation, spraying or atomization, coating in particular with a bar or a film puller, coating with a slotted head, immersion, roll-to-roll printing, screen printing, flexography, lithography, electrospinning and inkjet printing.

[0106] According to certain embodiments, the printing of layer L1 (3) and the optional step of printing layer L2 (4) can be implemented by coating, in particular with a bar or a film puller ("bar coating" in English) and / or the printing of said at least one electronic circuit (6) is implemented by screen printing.

[0107] When the electroactive polymer is a ferroelectric polymer, the method may comprise a step of polarizing the electronic circuit after it has been printed and / or covered with an optional L2 layer.

[0108] The invention finally relates to a method for transferring a mother substrate onto a daughter substrate of a device comprising: i) providing a device according to the invention; ii) depositing said device onto said daughter substrate by means of an adhesive; and, iii) removing the mother substrate.

[0109] Examples

[0110] A mother substrate was used, being an A4 sheet of polyethylene terephthalate 120 μm thick (PET; Melinex® ST506 marketed by the Dupont company).

[0111] A 17% by weight solution of P(VDF-co-TrFE) (VDF: TrFE 80 mol%: 20 mol%; Piezotech® FC, marketed by Arkema) in triethyl phosphate was deposited on this substrate by coating. The coater knife was adjusted so that the final layer, once the solvent had evaporated, was 1 micron. The solvent was evaporated at 130°C, placing the mother substrate and its coating layer in an oven for 20 min. A layer L1 of P(VDF-co-TrFE) was thus printed on the surface of the mother substrate.

[0112] On the L1 layer a transducer was printed by screen printing, according to these parameters:

[0113] 1) PEDOT-PSS (Orgacon® ELP-3155, Agfa). Using a dedicated screen printing screen to deposit 0.5 um after evaporation. Evaporation of the solvent at 140 °C for 10 min in an oven.

[0114] 2) Ink P (P(VDF-co-TrFE) 17%wt, in TEP). Screen printing screen of 100-40 giving a final thickness after evaporation of ~1.5 pm. Evaporation of the solvent at 140 °C for 20 min in an oven.

[0115] Step 2 was performed 3 times to obtain a final thickness of 4.5 um.

[0116] 3) PEDOT-PSS (Orgacon® ELP-3155, Agfa). Use of a screen printing screen to deposit 0.5 um after evaporation. Evaporation of the solvent at 140 °C for 10 min in an oven.

[0117] Once printed, the transducer was polarized by applying an electric field by contact to reach 100V / um. The voltage was applied gradually in 50V steps with a sinusoidal signal. It was carried out at room temperature (23°C) and was applied to the two PEDOT electrodes.

[0118] For the transfer of the transducer from the mother substrate to the daughter substrate, a pressure-sensitive adhesive (3M™ Adhesive Transfer Tape 465) was deposited as a film on the transducer.

[0119] The patch thus formed was deposited directly onto the daughter substrate and pressure was applied.

[0120] Then the mother substrate was gently removed by hand. Finally, the transducer / protective layer L1 was deposited on the daughter substrate and the protective layer L1 was in direct contact with the ambient air.

Claims

Claims 1. Device (1), suitable for transferring an electronic circuit (6) from a mother substrate (2) to a daughter substrate, comprising: a. a mother substrate (2), with a surface SM; b. a layer L1 (3) of polymer composition c1, with a surface Su, arranged on all or part of the mother substrate (2); c. at least one electronic circuit (6), with a surface ST, comprising at least one transducer (60) and optionally one or more conductive tracks (71, 72), said at least one electronic circuit being arranged on all or part of the layer L1 (3) and adhering to the layer L1, said transducer (6) comprising at least two conductive electrodes (61, 62; 66, 67) separated by one or more layers of electroactive polymer composition (63; 68); d. optionally, a layer L2 (4) of polymer composition c2, arranged on all or part of the free surface of the stack formed by the layer L1 (3) and said at least one electronic circuit (6) and adhering thereto; and, e.optionally, a layer L3 (5) of an adhesive or an adhesive precursor, the layer L3 being arranged on all or part of the free surface of the stack formed by the layer L1 (3), said at least one electronic circuit (6), and where appropriate the layer L2 (4) and adhering thereto; said layer L1 (3) being fixed to the mother substrate (2) in a removable manner.

2. Device according to claim 1, in which the electroactive fluorinated polymer comprises repeating units derived from vinylidene fluoride (VDF) and vinylidene trifluoride (TrFE), the molar proportion of the unit derived from TrFE being from 15% to 50% relative to the total number of moles of the units derived from VDF and TrFE.

3. Device according to either of claims 1 and 2, in which the composition c1 of the layer L1, and where appropriate the composition c2 of the layer L2, are independently of one another, essentially constituted, or constituted of a polymer comprising more than 40% by weight of a fluorinated monomer and / or of a polymer comprising more than 40% by weight of a repeating unit derived from an acrylic or methacrylic monomer.

4. Device according to any one of claims 1 to 3, comprising said layer L2, in which c1 and c2 are of the same chemical composition.

5. Device (1) according to any one of claims 1 to 4, wherein said at least one transducer (60) is a layered transducer formed by a first electrode layer (61), an electroactive composition layer (63) and a second electrode layer (62); or said transducer (60) is an interdigital transducer, formed by two comb electrodes (66, 67) and the electroactive composition layer (68), the two electrodes and the electroactive composition layer being arranged in the same plane.

6. Device (1) according to any one of claims 1 to 5, wherein said at least one electronic circuit (6) comprises one or more conductive tracks (71, 72) in electrical contact with one or more of the electrodes (61, 62; 66, 67) of said at least one transducer (60).

7. Device according to any one of claims 1 to 6, wherein the layer L1 (3) is arranged on all or part of the surface of the mother substrate (2), the layer L1 (3) having a low adhesion with the mother substrate (2), said low adhesion being high enough to avoid any delamination of the mother substrate (2) and the layer L1 (3) at a surface SM-T when a low stress is applied to said device and said low adhesion being low enough to allow adhesive failure at the surface SM-T when a moderate stress is applied to said device; said surface SM-T corresponding to the projection of the surface ST onto the surface SM of the mother substrate (2).

8. Device according to any one of claims 1 to 7, in which a layer (8) of a temporary adhesive is interposed between said mother substrate (2) and said layer L1(3) on all or part of the surface Su.

9. A method of manufacturing a device according to any one of claims 1 to 8 comprising: providing said mother substrate; an optional step of treating the SM surface of said mother substrate including the implementation of an adhesive, a temporary adhesive and / or an anti-adhesive; printing on the mother substrate, optionally treated, of said layer L1; printing on layer L1 of said at least one electronic circuit; an optional step of printing said layer L2 on all or part of the free surface of the stack formed by the printed layer L1 and said at least one printed electronic circuit; and, an optional step of depositing said layer L3 on all or part of the free surface of the stack formed by the printed layer L1, said at least one printed electronic circuit, and where appropriate the printed layer L2.

10. Manufacturing method according to claim 9, in which the printing of the layer L1 (3) and the optional step of printing the layer L2 (4) are implemented by coating, in particular with a bar or a film puller ("bar coating" in English) and / or the printing of said at least one electronic circuit (6) is implemented by screen printing.

11. Manufacturing method according to any one of claims 9 and 10, comprising a step of polarizing said at least one printed electronic circuit.

12. A method of transferring a mother substrate to a daughter substrate of a device comprising: i) providing a device according to any one of claims 1 to 8 and a daughter substrate; ii) depositing said device on said daughter substrate by means of an adhesive; and, iii) removing the mother substrate.

13. Composite (11) comprising: a. a layer L1 (3) of polymer composition c1, of surface Su; b. at least one electronic circuit (6), of surface ST, comprising at least one transducer (60), and optionally one or more tracks conductive (71, 72), said at least one electronic circuit being arranged on all or part of the layer L1 (3) and adhering to the layer L1, said transducer (6) comprising at least two conductive electrodes (61, 62; 66, 67) separated by one or more layers of electroactive polymer composition (63; 68); c. optionally, a layer L2 (4) of polymer composition c2, arranged on all or part of the free surface of the stack formed by the layer L1 (3) and said at least one electronic circuit (6), and adhering thereto; d. a layer L3' (7) of an adhesive, the layer L3' being arranged on all or part of the free surface of the stack formed by the layer L1 (3), said at least one electronic circuit (6), and where appropriate the layer L2 (4) and adhering thereto; e. a daughter substrate (10), arranged on the L3' layer (7) and adhering thereto; said composite being capable of being obtained according to the transfer method of claim 12.

14. Composite (11) according to claim 13, wherein said daughter substrate (10) is a stretchable or deformable substrate and / or a substrate having surface irregularities, in particular surface roughness.

15. Composite (11) according to claim 13, wherein said daughter substrate (10) is selected from a thermoplastic composite, a thermoset composite, a metal, a metal alloy, a woven or non-woven fabric, a wood, a paper, a plaster, skin and a leather.

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