Electronic device with anisotropic conductive adhesive

Abstract

The invention relates to an electronic device (100) comprising a support (110) and an electronic circuit (120) that comprises: - a first module (121); - comprising first connection pads (122); and - held in a cavity in the support (110) by means of an anisotropic conductive adhesive (130); - first conductive tracks (150) arranged on a substrate (170). It is characterised in that - the device (100) further comprises second connection pads (140) arranged on the substrate (170) opposite the first connection pads (122); wherein the second connection pads comprise a set of at least one recess (143) that allows the support (110) or the anisotropic conductive adhesive (130) to creep during the manufacture of the electronic device (100); - such that a first connection pad (122) is electrically connected to a respective track of the first set of conductive tracks (150) via the anisotropic adhesive (130) and a respective second connection pad (140).

Description

Electronic device with anisotropic conductive adhesive.

[0001] The present invention relates to the field of manufacturing electronic devices, in particular those enabling transactions to be carried out.

[0002] A "transaction" means a pre-programmed interactive operation in a "question-answer" format including searching for, entering or modifying information in a file or database.

[0003] Typically such electronic devices are used for example in identity documents or smart cards, including passports for an identity transaction, or in bank smart cards for banking transactions.

[0004] To secure transactions, various security measures are known to be implemented, including biometrics. On the hardware side, biometrics requires an electronic sensor, and on the functional side, implementing biometrics requires a preliminary enrollment step, which can be complex.

[0005] In the field of biometric smart cards, document FR3128301 filed by the applicant is known.

[0006] The present invention aims to further improve the performance of the solution proposed in document FR3128301, while broadening its application beyond biometrics.

[0007] More specifically, the invention relates, according to a first of its objects, to an electronic device (100), comprising a multilayer, substantially planar support (110) and an electronic circuit (120) arranged on the support (110) or in the support (110), the electronic circuit (120) comprising: • a first module (121), • comprising a set of first connection pads (122), integral with the first module (121), and • held in a first cavity of the support (110), by means of an anisotropic conductive adhesive (130) in contact with said first set of connection pads, the anisotropic conduction direction being secant and to the plane of the support (110), • a first set of conductive tracks (150), arranged on a substrate (170).

[0008] It is essentially characterized in that: • the electronic device (100) further comprises a set of second connection pads, arranged on the substrate (170), • each second connection pad (140) being arranged at right angles of a respective first connection pad (122); • each second connection pad (140) comprising: • a first face of the second connection pad (140) in contact with the anisotropic conductive adhesive (130), and a second face of the second connection pad (140), opposite the first face, in electrical contact with at least one respective conductive track of the first set of conductive tracks (150), • a set of at least one recess (143) which allows the creep of a part of at least one layer of the multilayer support (110) or the creep of the anisotropic conductive adhesive (130) during the manufacture of the electronic device (100), • such that at least one first connection pad (122) is electrically connected to a respective track of the first set of conductive tracks (150) via the anisotropic adhesive (130) and a respective second connection pad (140).

[0009]

[0010] It may be provided that the first set of conductive tracks (150) is produced by printing, for example by screen printing of a conductive material, for example printed copper; or by etching at least one layer of aluminum or copper, including a printed circuit (PCB), said first set of conductive tracks (150) being at least one of: • an antenna, and • a set of electrical connection tracks with a second module (200); the electronic circuit (120) may further comprise said second module (200).

[0011]

[0012] It can be provided that the first module (121) comprises one of: • a secure element, • a sensor, • a display screen (OTP), • a dynamic cryptogram, • a sound device, • a set of at least one LED.

[0013]

[0014] It can be provided that the substrate (170) on which the first set of conductive tracks (150) is arranged is a cellulose-based material, synthetic paper, polymer or epoxy (PET, PVC, PC, PI); and that the second connection pads may have, in cross section parallel to the plane of the support (110), a structure in the form of fish bones, snowflakes, spirals, honeycombs, or centripetal rays.

[0015]

[0016] We can predict that: • The first set of conductive tracks (150) is arranged on a first face of the substrate (170), • The electronic device (100) comprising a second set of conductive tracks (160), arranged on a second face of the substrate (170), opposite the first face of the substrate (170), at least one of the tracks of the second set being arranged in line with a second connection pad (140) and electrically connected to the latter by a via (180) passing through the substrate (170).

[0017]

[0018] It may be provided that at least one second connection pad (140) comprises a via (180), the via (180) comprising at least one recess (143); said second connection pad (140) may be solid or comprise at least one other recess (143).

[0019]

[0020] We can predict that:

[0021] The thickness of the second set of conductive tracks (160) is less than the thickness of the first set of conductive tracks (150), the thickness of the first set of conductive tracks (150) being less than or equal to the thickness of the second connection pad (140).

[0022]

[0023] A second module (200) may be provided, wherein said second module (200) comprises one of: • a secure element, • a sensor, • a display screen (OTP), • a dynamic cryptogram, • a sound device, • a set of at least one LED.

[0024]

[0025] According to another of its objects, the invention relates to a passport comprising an electronic device (100) according to the invention.

[0026]

[0027] According to another of its objects, the invention relates to a smart card (125) comprising an electronic device (100) according to the invention, in which said smart card (125) is a bank card or an identity card.

[0028]

[0029] The present invention therefore relates to any chip document.

[0030]

[0031] Other features and advantages of the present invention will become more clearly apparent upon reading the following description given by way of illustrative and non-limiting example and with reference to the appended figures. The figures are not necessarily to scale. Certain details may have been omitted, others enlarged, to facilitate understanding.

[0032]

[0033] [Fig. 1A] illustrates an embodiment of an electronic device according to the invention,

[0034] [Fig. 1B] illustrates an embodiment of an electronic device according to the invention,

[0035] [Fig. 2A] illustrates an embodiment of a second connection pad according to the invention,

[0036] [Fig. 2B] illustrates an embodiment of a second connection pad according to the invention,

[0037] [Fig. 2C] illustrates an embodiment of a second connection pad according to the invention,

[0038] [Fig. 2D] illustrates an embodiment of a second connection pad according to the invention,

[0039] [Fig. 2E] illustrates an embodiment of a second connection pad according to the invention,

[0040] [Fig. 2F] illustrates an embodiment of a second connection pad according to the invention in three-dimensional view.

[0041] [Fig. 3] illustrates an embodiment of the electrical connection between a second connection pad according to the invention and a via,

[0042] [Fig. 4A] illustrates, in cross-section, an electronic circuit according to the invention comprising a single antenna, with a polymer-based support,

[0043] [Fig. 4B] illustrates the circuit of Figure 4A before lamination,

[0044] [Fig. 4C] illustrates the circuit of figure 4B after lamination, with a machining plane AA, and creep of the support,

[0045] [Fig. 4D] illustrates the circuit of Figure 4C after machining according to the machining plane AA,

[0046] [Fig. 4E] illustrates the circuit of Figure 4D after inset,

[0047] [Fig. 5A] illustrates, in cross-section, an electronic circuit according to the invention comprising a single antenna, with a cellulose-based support,

[0048] [Fig. 5B] illustrates the circuit of Figure 5A before lamination,

[0049] [Fig. 5C] illustrates the circuit of Figure 5B after lamination, with a machining plane AA,

[0050] [Fig. 5D] illustrates the circuit of Figure 5C after machining according to the machining plane AA,

[0051] [Fig. 5E] illustrates the circuit of Figure 5D after embedding, and creep of the anisotropic conductive adhesive,

[0052] [Fig. 6] illustrates in top view, an embodiment of an electronic circuit according to the invention comprising two modules connected to each other by means of respective second connection pads,

[0053] [Fig. 7], Illustrates the diagram of Figure 6 in which two second connection pads comprise a respective via,

[0054] [Fig. 8] illustrates the diagram of Figure 1B in which the thickness of the first conductive track is equal to the thickness of the second conductive track, and less than the thickness of a second connection pad. Detailed description

[0055] Figure 1A illustrates an embodiment of an electronic device according to the invention, in which a first module is simplified, and Figure 1B illustrates the embodiment of Figure 1A in which the first module is more detailed.

[0056] In Figure 1B, certain main components of the first module are illustrated more precisely, in particular a set of contact pads 126 of the module, accessible from outside the electronic device and typically allowing galvanic contact with the tips of a reader.

[0057] Also illustrated is a chip 125 encapsulated in a drop of coating resin 124. The chip 125 is electrically connected to the first connection pads by a set of connection wires 123.

[0058] The electronic device comprises a substantially planar support 110. Preferably, the support 110 is a multi-layer support 110. For example, for a smart card 125, the support 110 is the card body. For example, the support 110 is made of a polymer, typically a plastic, and for example PVC.

[0059] Preferably, the support 110 comprises a first cavity 111 (illustrated in FIG. 1A) allowing a first module described below to be inserted therein.

[0060] The electronic device comprises an electronic circuit arranged on the support 110 or in the support 110, for example between two adjacent layers of a multi-layer support 110.

[0061] For example, the electronic circuit is a radio frequency circuit.

[0062] The electronic circuit includes a first module.

[0063] It can be provided that the electronic circuit further comprises a second module 200, as illustrated in dotted lines in FIG. 6.

[0064] For example, any one of the first module and the second module 200 may be a secure element, in particular for banking or identity transactions.

[0065] The first module or the second module 200 may also be a sensor, for example a temperature, pressure, humidity sensor, a biomedical sensor, for example for measuring blood pressure, a biometric sensor, etc.

[0066] The first module or the second module 200 may also be a display screen, in particular for one-time passwords (OTP) or a dynamic code or dynamic cryptogram (DCVV).

[0067] The first module or the second module 200 may also be a sound device, for example a buzzer.

[0068] The first module or the second module 200 may also be a set of at least one LED.

[0069] The first module or the second module 200 comprises a set of at least one first connection pad 122, secured to the first module or the second module 200, respectively.

[0070] The first connection pads 122 allow, for example, the transfer of data or energy to the first module 121 or from the first module 121.

[0071] Similarly, when the electronic device comprises a second module 200, the first connection pads allow for example the transfer of data or energy to the second module 200 or from the second module 200.

[0072] The first module 121 is arranged in a first cavity 111 of the support 110, and held therein by means of an anisotropic conductive adhesive 130 which is in contact with said first set of connection pads. For example, the anisotropic conductive adhesive is ACF or ACP where, for example, ACF means Anistropic Conductive Film and ACP means Anistropic Conductive Paste.

[0073] The anisotropic conductive adhesive 130 is for example in the form of a film. It allows electrical conduction in a predetermined direction. In this case, the anisotropic conduction direction is secant, and preferably substantially perpendicular, to the plane of the support 110.

[0074] The electronic circuit also comprises a first set of conductive tracks 150, arranged on a substrate 170.

[0075] More specifically, the first set of conductive tracks 150 is arranged on a first face of the substrate 170.

[0076] For example, the first set of conductive tracks 150 comprises an antenna.

[0077] The first set of conductive tracks 150 may also comprise a set of electrical connection tracks with a second module 200, in particular as illustrated in FIG. 6.

[0078] For example, substrate 170 is an antenna substrate.

[0079] For example, the substrate 170 comprises a polymer-based material, in particular plastic, or epoxy. For example, the substrate 170 comprises at least one of: PET, PVC, PC, PI.

[0080] It may also be provided that the substrate 170 comprises a cellulose-based material, for example cellulose paper, cardboard or wood, or synthetic paper-based.

[0081] The support 110 may also comprise a polymer-based material, in particular plastic, or epoxy. For example, the support 110 comprises at least one of: PET, PVC, PC or PI.

[0082] The support 110 may also comprise a cellulose-based material, for example cellulose paper, cardboard or wood, or synthetic paper-based.

[0083] As described later, a portion of the anisotropic conductive adhesive 130 may flow into the recesses 143 described later.

[0084] Or a portion of the support 110 itself may flow into the recesses 143 described later.

[0085] Preferably, the substrate 170 is at least locally planar and coplanar with the support 110. However, when viewed in cross-section, the substrate 170 may be in the form of a staircase step(s).

[0086] For example, the first set of conductive tracks 150 is produced by printing, for example by screen printing of a conductive material, by example in printed copper, excluding wire copper.

[0087] The first set of conductive tracks can also be made by etching at least one layer of aluminum or copper, including a printed circuit board (PCB).

[0088] According to the invention, the electronic device further comprises a set of second connection pads 140, arranged on the substrate 170.

[0089] The second connection pads 140 may have, in cross-section parallel to the plane of the support 110, a structure in the form of fish bones (FIG. 2B), snowflakes (FIG. 2C), spirals (FIG. 2E, FIG. 3), honeycombs (FIG. 2D), or centripetal spokes (FIG. 2A), etc. In FIG. 6, a second connection pad 140, in this case in the form of fish bones, is illustrated in dotted lines. The metal structure of the second connection pads 140 may not be regular or symmetrical, when viewed from above in the XOY plane.

[0090] For simplification, we mean indistinctly “set of first connection pads” 122 and “first set of connection pads”; and “set of second connection pads” 140 and “second set of connection pads”.

[0091] Each second connection pad comprises a first face and a second face 142, opposite the first face 141.

[0092] The first face 141 of a second connection pad is in physical and electrical contact with the anisotropic conductive adhesive 130, and the second face 142 of a second connection pad 140 is in physical and electrical contact with at least one respective conductive track 150 of the first set of conductive tracks, if necessary by means of a via 180.

[0093] Thus, in an orthonormal XYZ frame of reference, illustrated in FIG. 1 B, the anisotropic conductive adhesive 130 has an anisotropic conduction direction along the Z axis, in this case perpendicular to the XY plane of the support 10. The electrical conduction therefore takes place in this case along the Z axis.

[0094] Thus a first connection pad 122 is electrically connected to a second connection pad 140, in this case arranged in line with the latter, by means of the anisotropic conductive adhesive 130. As the latter is anisotropic, it can be arranged in the form of a film.

[0095] In this way, at least a first connection pad 122 is electrically connected to a respective track 150 of the first set of conductive tracks by means of the anisotropic adhesive 130 and a second connection pad 122. connection 140.

[0096] Preferably, each second connection pad is arranged in line with a respective first connection pad. However, depending on the anisotropic conduction direction of the anisotropic conductive film 130, each second connection pad may be arranged offset from a vertical axis of a respective first connection pad.

[0097] Each second connection pad comprises a set of at least one recess 143, which is in the form of a through hole or a blind hole.

[0098] As described below, the recess 143 allows the flow of a portion of at least one layer of the multilayer support 110 or the flow of the adhesive of the anisotropic conductive film 130 during the manufacture of the electronic device; in particular for a smart card during the lamination, inlaying, or “inlay” thereof, that is to say the assembly of an insulating support, an antenna and an electronic chip 125 or an integrated circuit.

[0099] According to a first embodiment, the support 110 comprises a polymer-based material. The production of an electronic device according to the invention is illustrated in FIGS. 4A to 4E.

[0100] In Figures 4A to 4E, a second connection pad 140 is illustrated in dotted lines, and comprises in a purely illustrative manner two electrically conductive posts 144, 145, for example illustrated in Figure 6.

[0101] Figure 4A illustrates a set of second connection pads, which in this case are a single antenna, with a plastic support 110.

[0102] In Figure 4B, a multilayer support 110 is deposited on the set of second connection pads.

[0103] As illustrated in Figure 4C, with heat and pressure, the multi-layer support 110 flows into the interstices, including into the recesses 143.

[0104] We then plan to machine according to the machining plane AA, in this case parallel to the XY plane, the result of which is illustrated in figure 4D.

[0105] The insertion with the first module is illustrated in Figure 4E. It has been illustrated that a first connection pad can be in contact with several conductive (for example metallic) uprights of the same second connection pad, for example in the form of fish bones, a top view of which, in the XY plane, is illustrated in Figure 6.

[0106] According to a second embodiment, the support 110 comprises a cellulose-based material, for example cellulose paper. The production of an electronic device according to the invention is illustrated in FIGS. 5A to 5E.

[0107] In Figures 5A to 5E, a second connection pad 140 is illustrated in dotted lines, and comprises in a purely illustrative manner two electrically conductive posts 144, 145, for example illustrated in Figure 6.

[0108] Figure 5A illustrates a set of second connection pads, which are in this case a single antenna, on a substrate 170 made of plastic or cellulosic material.

[0109] In Figure 5B, a support 110 made of cellulose or synthetic paper is deposited, or stacked, on all of the second connection pads 140.

[0110] As illustrated in Figure 5C, with heat and pressure, the cellulose-based support 110 flows into the interstices, including into the recesses 143, but less than with a plastic-based support 110, i.e. without completely filling said interstices. [OR I] We then plan to machine according to the machining plane AA, in this case parallel to the XY plane, the result of which is illustrated in figure 5D.

[0112] After machining the interstices do not include any plastic-based support 110 which would have flowed there, any possible flow remaining above the cutting line of the machining plane AA.

[0113] The insertion with the first module is illustrated in Figure 5E. It has been illustrated that a first connection pad can be in contact with several conductive (for example metallic) uprights of the same second connection pad, for example in the form of fish bones, a top view of which, in the XY plane, is illustrated in Figure 6.

[0114] During insertion, due to the temperature and pressure, the anisotropic conductive adhesive 130 flows in particular into the recesses 143 (see FIG. 5E).

[0115] Comparing the above two embodiments, according to the first embodiment in which the support 110 comprises a polymer-based material, the support 110 flows into the recesses 143; whereas according to the second embodiment in which the support 110 comprises a cellulose-based material, the anisotropic conductive adhesive 130 flows into the recesses 143.

[0116] It can be provided that the electronic device comprises a second set of conductive tracks 160.

[0117] In this case, the tracks of the second set of conductive tracks 160 are arranged on a second face of the substrate 170, opposite the first face of the substrate 170.

[0118] At least one of the tracks of the second set of conductive tracks 160 is arranged in line with a second connection pad 140 and electrically connected to the latter by a via 180, also known by the Anglicism crimp, which passes through the substrate 170.

[0119] It can be provided, as illustrated for example in FIG. 6, that a via 180 is adjacent to a second connection pad 140 and electrically connected to it by metal.

[0120] It is also possible, as illustrated for example in FIG. 7, for a via 180 to be integrated into a second connection pad 140. In FIG. 7, two second connection pads 140, each comprising a via 180, are illustrated in dotted lines. This configuration advantageously makes it possible to reduce the surface area of ​​a second connection pad 140 and its via 180, and to limit the ghost image effect described below.

[0121] It can be provided that the thickness of the tracks of the second set of conductive tracks 160 is less than the thickness of the tracks of the first set of conductive tracks 150.

[0122] Preferably, the tracks of the second set of conductive tracks 160 are made of aluminum.

[0123] If the thickness of the tracks of the second set of conductive tracks 160 is greater than a threshold value, during the manufacture of a smart card 125, this may result in a ghost image of these tracks after lamination with plastic layers.

[0124] To limit, or even eliminate this effect, it can be provided that the thickness of the first set of conductive tracks 150 is less than the thickness of the second connection pad 140, and in this case equal to the thickness of the second set of conductive tracks 160, so that there is only an excess thickness of metal locally at the level of the second connection pads 140, as illustrated in FIG. 8.

[0125] The electronic device can advantageously be implemented in a passport or other identity document, official (driving license, etc.) or unofficial (company badge, secure access, etc.); as well as in a smart card 125, in particular a bank card, a subscription card, a transport card, an access card, etc.

[0126] Nomenclature 100 electronic device 110 multi-layer support 111 first cavity of the support 120 electronic circuit 121 first module 122 first connection pad 123 connecting wire 124 coating resin (drop) 125 chip 126 module contact pads 130 anisotropic conductive adhesive 140 second connection pad 141 first face of the second connection pad 142 second face of the second connection pad 143 recess 144 electrically conductive amount of a second connection pad 145 electrically conductive amount of a second connection pad (140) 150 first conductive track 160 second conductive track 170 substrate 180 via 200 second module

Claims

Claims 1. Electronic device (100), comprising a multilayer, substantially planar support (110) and an electronic circuit (120) arranged on the support (110) or in the support (110), the electronic circuit (120) comprising: • a first module (121), • comprising a set of first connection pads (122), integral with the first module (121), and • held in a first cavity of the support (110), by means of an anisotropic conductive adhesive (130) in contact with said first set of connection pads, the anisotropic conduction direction being secant to the plane of the support (110), • a first set of conductive tracks (150), arranged on a substrate (170), characterized in that • the electronic device (100) further comprises a set of second connection pads (140), arranged on the substrate (170), • each second connection pad (140) being arranged in line with a respective first connection pad (122); • each second connection pad (140) comprising: • a first face of the second connection pad (140) in contact with the anisotropic conductive adhesive (130), and a second face of the second connection pad (140), opposite the first face, in electrical contact with at least one respective conductive track of the first set of conductive tracks (150), • a set of at least one recess (143) which allows the creep of a part of at least one layer of the multilayer support (110) or the creep of the anisotropic conductive adhesive (130) during the manufacture of the electronic device (100), • such that at least one first connection pad (122) is electrically connected to a respective track of the first set of conductive tracks (150) via the anisotropic adhesive (130) and a respective second connection pad (140).

2. Electronic device (100) according to claim 1, wherein the first set of conductive tracks (150) is produced by printing, for example by screen printing of a conductive material, for example printed copper; or by etching at least one layer of aluminum or copper, including a printed circuit (PCB), said first set of conductive tracks (150) being at least one of: • an antenna, and • a set of electrical connection tracks with a second module (200); the electronic circuit (120) may further comprise said second module (200).

3. Electronic device (100) according to any one of the preceding claims, wherein the first module (121) comprises one of: • a secure element, • a sensor, • a display screen (OTP), • a dynamic cryptogram, • a sound device, • a set of at least one LED.

4. Electronic device (100) according to any one of the preceding claims, wherein the substrate (170) on which the first set of conductive tracks (150) is arranged is a material based on cellulose, synthetic paper, polymer or epoxy (PET, PVC, PC, PI); and wherein the second connection pads may have, in cross section parallel to the plane of the support (110), a structure in the form of fish bones, snowflakes, spirals, honeycombs, or centripetal rays.

5. Electronic device (100) according to any one of the preceding claims, wherein: • The first set of conductive tracks (150) is arranged on a first face of the substrate (170), • The electronic device (100) comprising a second set of conductive tracks (160), arranged on a second face of the substrate (170), opposite the first face of the substrate (170), at least one of the tracks of the second set being arranged in line with a second connection pad (140) and electrically connected thereto by a via (180) passing through the substrate (170).

6. Electronic device (100) according to claim 5, wherein at least one second connection pad (140) comprises a via (180), the via (180) comprising at least one recess (143); said second connection pad (140) may be solid or comprise at least one other recess (143).

7. Electronic device (100) according to claim 5 or 6, wherein: The thickness of the second set of conductive tracks (160) is less than or equal to the thickness of the first set of conductive tracks (150), the thickness of the first set of conductive tracks (150) being less than or equal to the thickness of the second connection pad (140).

8. Electronic device (100) according to any one of claims 2 to 6, comprising said second module (200), wherein said second module (200) comprises one of: • a secure element, • a sensor, • a display screen (OTP), • a dynamic cryptogram, • a sound device, • a set of at least one LED.

9. Passport comprising an electronic device (100) according to any one of the preceding claims.

10. Smart card (125) comprising an electronic device (100) according to any one of claims 1 to 8, wherein said smart card (125) is a bank card or an identity card.

Images