ELECTRONIC MODULE FOR A CARD WITH AT LEAST ONE ANTENNA AND MANUFACTURING METHOD FOR IT

Description

[0001] The invention relates to an electronic module for a card containing at least one antenna and a method of manufacturing it. The electronic module can be integrated into a contactless transaction card, a mixed-function card or "dual card" comprising a contact function and a contactless function.

[0002] The invention applies regardless of the material used to make the connections, gold wires, aluminum wires or any other material capable of making the required connections between an integrated circuit (chip) and an antenna or between an integrated circuit and one or more connection wells or "bonding" wells.

[0003] The electronic module according to the invention can be used in any portable device, such as a card, in the field of identity, transport, banking, access control, health and also in the field of telecommunications.

[0004] The electronic module integrated in a smart card generally comprises a printed circuit equipped with a chip or integrated circuit, and communication means allowing the transmission of data from the chip to a card reader device. The data transmission means consist, for example, of one or more antennas and / or a connector.

[0005] A contact smart card will have a connector for reading the card information by a suitable reader, the connector comprising contacts electrically connected to the chip. These contacts consist of conductive metal tracks on the surface of the support to make an electrical contact connection with the card reader device.

[0006] A contactless smart card has one or more antennas connected directly, or via a so-called “booster” antenna, to a card reader device.

[0007] A dual chip card has both functions for exchanging data and both types of connections mentioned above.

[0008] One of the problems encountered in the manufacture of electronic modules intended to be inserted into cards, or any other equivalent support, is in particular the height of the connection wires linking the antenna buried within the card and the chip contained in the latter.

[0009] Another difficulty encountered arises from the connection of one or more of the chip's pads to bonding wells. The chip or integrated circuit's connection pads having a specific layout, as well as the layout of the bonding wells with respect to the surface contacts of the support, can lead to crossed connection wires or the presence of excessively long wires.

[0010] Documents EP2892012, US2013 / 062419, US2015 / 269471 and EP3059698 disclose an electronic module comprising an intermediate connection pad.

[0011] As illustrated in the figure 1 , in certain configurations, wires used for the connection between an antenna and an integrated circuit will "cross over".

[0012] An electronic module 1 is known comprising a substrate on which one or more conductive tracks forming an antenna are deposited. The conductive tracks have a first end forming the inner end of the antenna and a second end forming the outer end of the antenna. A chip is connected via 12p connection pads, to the inner end of the antenna, to the outer end of the antenna and to bonding wells. The technique used is a connection wire wiring technique better known by the English expression "wire bond". In the prior art, the connection wires 14 cross.

[0013] The idea of ​​the present invention is based on a new approach for the manufacture of an electronic module and the resulting module structure, which consists in particular of using one or more intermediate connection pads arranged "inside the antenna" and which allow the necessary electrical connections to be made. The presence of these intermediate connection pads makes it possible to minimize the length of the connection wires and / or to prevent the connection wires from crossing.

[0014] The expression "arranged inside" the antenna means in the present invention that a so-called "intermediate" pad will be arranged on the antenna support inside an antenna loop (or a perimeter) formed by the wires or turns constituting the antenna.

[0015] The expressions “intermediate connection pad” or “intermediate pad” designate the same element.

[0016] The invention relates to an electronic module according to claim 1.

[0017] The connection between a connection pad of the integrated circuit and at least one of the electrically conductive tracks or at least one of the connection wells is made with an aluminum wire or with a gold wire.

[0018] The integrated circuit can be an electronic chip.

[0019] The invention also relates to a method of manufacturing an electronic module according to claim 9.

[0020] According to an alternative embodiment, said electrically conductive tracks are deposited to form at least one antenna comprising a first end and a second end, and a connection is made between said intermediate connection pad with at least one external end of the antenna via a first connection wire and to at least one connection pad of the integrated circuit via a second connection wire.

[0021] The intermediate connection pad(s) can also be electrically deposited when creating a central opening in the substrate, said central opening having dimensions chosen to accommodate an integrated circuit.

[0022] The connection between at least one electrically conductive track or bonding well and at least one of the intermediate connection pads and between at least one of the intermediate connection pads and one of the pads of at least one integrated circuit can be made using a gold wire or an aluminum wire.

[0023] The method may further comprise a step of encapsulating the electrically conductive wires, the intermediate connection pads and the integrated circuit using a protective resin.

[0024] Other characteristics, details and advantages of the invention will emerge from reading the description given with reference to the appended drawings given by way of non-limiting example and which represent, respectively: [ Fig.1 ] There figure 1 is an illustration of a first example of embodiment of the electronic module according to the invention, [ Fig.2 ] There figure 2 is an enlarged view of the first example of the embodiment of the figure 1 ; [ Fig.3 ] There figure 3 is a variant of figures 1 And 2 with an intermediate pad allowing the chip to be connected to a contact on the surface of the support, avoiding the crossing of connection wires; [ Fig. 4 ] There figure 4 is an alternative embodiment for the shape of an intermediate connection pad; [ Fig.5 ] There figure 5 is a succession of steps implemented for an example of a manufacturing process for the electronic module according to the invention

[0025] The figure 1 illustrates an electronic module 2 according to the invention comprising a substrate 20 on which one or more conductive tracks 21 forming an antenna are deposited. The conductive tracks comprise a first end 21i forming the inner end of the antenna 21 and a second end 21e forming the outer end of the antenna 21. A chip 22 is connected via several connection pads 22p, on the one hand to the inner end 21i of the antenna 21 and to the outer end 21e of the antenna 21 via an intermediate connection pad 25 on at least one face 21 of the substrate 20 as will be detailed later and on the other hand to bonding wells 23j. The technique used for the connection is a connection wire wiring technique 24, better known by the English expression “wire bond”.The connecting wires can be made of aluminum, gold, or any other electrically conductive material that connects the chip to the antenna and the surface contacts of the support.

[0026] The substrate 20 comprises one or more connection pads called “intermediate connection pads” 25. For reasons of simplification, the figure 1 illustrates the case where an intermediate pad 25 is used to connect the external end 21e of the antenna 21 to a connection pad 22p of the chip. The connection wire 24, usually made up of a single part for connecting the chip and the external end of the antenna, is divided into two, a first part 241 which connects the external end 21e of the antenna to a first area 252 of the intermediate pad 25 and a second part 242 which connects a second area 251 of the intermediate pad 25 to a pad 22e of the chip 22. In this way, the length of the part of the connection wire is less than the length of the wire directly connecting the external end of the antenna to the chip according to prior art techniques. This advantageously makes it possible to reduce the height of the loop of the wire thus formed. A third part of the connection wire 243 will connect the internal end 21i of the antenna 21 to a pad 22i of the chip 22.

[0027] An opening 26 can be made in the substrate for the passage of the integrated circuit, for example. Its dimensions are chosen accordingly. Without departing from the scope of the invention, the architecture according to the invention can also be implemented for a substrate without an opening, where the integrated circuit is placed on one of the faces of the substrate.

[0028] On the figure 1 , a single intermediate connection pad has been illustrated. This intermediate connection pad can be divided into several pads, taking different shapes and which are distributed in different places on the substrate in order to allow the connection of the wires, to reduce the size of these wires and to prevent them from crossing. The number of intermediate connection pads is notably chosen according to the number and arrangement of integrated circuits arranged on the substrate.

[0029] In the case of a connecting wire made of aluminum, the arrangement illustrated in figure 1 facilitates the installation of wires and their connections, in particular by allowing several connection wires to be arranged in parallel.

[0030] In the case of a gold connection wire, this structure offers more flexibility in wiring, especially in the case of an electronic module comprising several integrated circuits or chips.

[0031] The intermediate connection pad(s) is a metallized pad. Since the antenna is generally made of copper, the metallization of the pad will be composed, in addition to copper, of nickel and gold or any other material allowing an electrical connection to be made.

[0032] In order to keep the connection wires in parallel, particularly in the case of aluminum wires, the intermediate connection pad may contain at least two connection pads arranged in such a way that the connection wire between the external end of the antenna and the intermediate pad, the connection wire between the intermediate pad and the chip, and the connection wire between the internal end of the antenna and the chip are arranged substantially parallel to each other. figure 2 illustrates three connecting wires 241, 242, 243 substantially parallel to each other.

[0033] The geometry and dimensions of an intermediate connection pad will be chosen, in particular, according to the potential arrival direction of the connection wire. For example, the shape of the intermediate connection pad can take an oblong shape in the direction parallel to the arrival of the connection wire. The dimensions of this intermediate connection pad are chosen according to a compromise between the cost of metallization of the pad and the size which must be sufficient to accommodate a connection wire. The technique for the connection made with a gold wire is known under the expression "ball-wedge bonding" which consists of placing a gold ball on the chip and a fixing pad or "wedge" on the substrate. For the connection made with an aluminum wire, the technique is known under the Anglo-Saxon expression "wedge-wedge bonding" with two fixing pads.In the case of metallization carried out with precious metals, we will seek to reduce the cost resulting from the metallization and to optimize the cost / size compromise. The deposition of these precious metals can be carried out, for example, by selective electroplating.

[0034] During the fabrication of the antenna on the substrate, the intermediate connection pad(s) are connected. Thus, during the step of depositing the materials allowing the wire connection (generally Nickel and Gold), and requiring the supply of a current, the intermediate pot(s) are powered in the same way as the antenna itself. The electrical insulation of these intermediate pads is carried out, for example, during the internal cutting of the substrate, allowing access to the contact on the surface of the substrate and the finalization of the electronic module. Electrical insulation can also be carried out by the punching technique better known by the Anglo-Saxon abbreviation "punch" during de-short-circuiting or testing.

[0035] The chip and antenna assembly will, for example, be protected by a resin, not shown for reasons of simplification of the figure, according to techniques known from the prior art. For example, the resin will be deposited via the encapsulation technique known by the English abbreviation "Dam and Fill", or by transfer molding. The resin may be an encapsulation resin of the coating or "potting" type. It is also possible to use epoxy base resins known by the term "glob top".

[0036] The chip will be held in place on the antenna support (substrate), for example by means of an adhesive or any other technique known to those skilled in the art.

[0037] There figure 3 illustrates an alternative embodiment for a bonding well (connection to an ISO contact, on the contact face) which is inside the wire bundle forming an antenna to avoid wire crossings during wiring, and to make a substrate or tape design universal, to shorten the wires. In this example, a bonding well 234 is connected to a pad 221 of the chip 22 via a first connection wire 41 in a first area of ​​an intermediate connection pad 42 and a second connection wire 44 in a second area of ​​the same intermediate connection pad.

[0038] In the particular embodiment of the figure 3 , the antenna formed by the electrically conductive tracks 21 has a bypass zone Zc. This bypass zone Zc is intended to bypass the external end 21e of the antenna. This bypass zone Zc extends towards the inside of said antenna. The intermediate connection pad here partially follows the internal periphery formed by the antenna. This connection pad then has a complementary shape 351 to the bypass zone Zc and thus partially surrounding it. More particularly, the complementary shape 351 is here partially curved. In other words, this complementary shape 351 has a bean shape.

[0039] There figure 4 illustrates a variant embodiment of the figure 3 where the shape of the intermediate pad 25 “follows” the entire internal periphery 36 formed by the most central tracks and constituting the antenna. The intermediate pad 25 has a first part having the complementary shape 351 or bean shape and a second part 352 in the form of an electrically conductive track. This second part 352 extends over the entire internal periphery 36 to completely surround the integrated circuit 22. Preferably, this second part 352 is in the form of a thick ribbon which follows the internal periphery of the wires forming the antenna. Such an arrangement makes it possible in particular to more easily connect the different pads of the chip, which can be distributed around the periphery of the chip, to one or more bonding wells 231, 232, 233, 234, 235 ( Fig.4 ), connected for example to an external terminal such as an ISO type communication interface, avoiding crossing the connection wires.

[0040] Without departing from the scope of the invention, the electronic module may comprise a substrate with a double antenna, deposited on each of the faces of the substrate.

[0041] There figure 5 illustrates an example of a series of steps for the manufacture of an electronic module according to the invention which may include, for example, the following steps: 501 - A substrate is provided on which a set of metal tracks is deposited, using a technique known to those skilled in the art, on at least one face of the substrate to form, for example, one or more antennas,

[0042] For example, to make an electrically conductive contact, a sheet of material will be immersed in an electrolytic solution and said electrically conductive sheet will be made integral with the substrate, 502 - At least one chip or integrated circuit is deposited in the center of the substrate, 503 - One or more bonding wells are made, this step being optional, 504 - One or more intermediate connection pads are deposited, the dimensions and position(s) of which are chosen in such a way that the wire connections between the pads of the chip and the two ends of the antenna do not cross, and

[0043] An intermediate pad is electrically separated from the antenna before it is connected by the connection wires. For example, the electrical separation (isolation) is carried out after the substrate finishing steps, so that the intermediate connection pad has the electrolytic deposition layers necessary for wire bonding. This electrical separation 505 is for example carried out when creating a central opening (26 figure 1 ) intended to accommodate the integrated circuit at a lower altitude on the finished product,

[0044] The connection is made between at least one of the intermediate pads and one end of the antenna 21 and between at least one of the intermediate pads with one of the 22p pads of the integrated circuit 22, and / or with a bonding well, 506, 507 - An encapsulation resin is deposited to protect the antenna and the integrated circuit.

[0045] The dielectric substrate is for example glass-epoxy, Polyethylene Terephthalate, Polyethylene Naphthalate, polyimide, etc.

[0046] The electronic module thus obtained can be positioned in a cavity of the card body in a cavity of the card body using hot melt glue.

[0047] The module according to the invention and its manufacturing method make it possible to offer a module in which the height of the loops formed by the connection wires is lower than the heights found in the electronic modules of the prior art. This makes it possible to make the module more compact, to reduce the thickness of this module. Such a structure makes it easier to wire with aluminum wires. The presence of an intermediate pad prevents the connection wires from crossing.

Claims

1. An electronic module (2) including: - a substrate (20) on which several electrically-conductive tracks (21) in the form of several loops deposited over a face of said substrate (20) forming at least one antenna are arranged; - at least one integrated circuit (22) comprising several connecting pads (22p); at least one intermediate connecting pad (25) located on a face (201) of said substrate (20) and extending over at least one portion of the inner periphery (36) formed by said electrically-conductive tracks (21), said intermediate connecting pad (25) being connected at a first point to said electrically-conductive tracks (21) or to a connection well (231, 232, 233) at the level of the substrate (20) by means of a first connecting wire (241), and said intermediate connecting pad (25) being connected at a second point to at least one pad of said integrated circuit (22) by means of a second connecting wire (242), and said intermediate connecting pad (25) being connected to at least one outer end (21e) of said antenna via said first connecting wire (241) and to at least one connecting pad (22p) of said integrated circuit (22) via said second connecting wire (242), characterized in that said intermediate connecting pad (25) is located on the face (201) of said substrate (20) carrying said electrically conductive wires (21).

2. The electronic module according to claim 1, characterized in that it includes a connecting wire connecting the outer end (21e) of the antenna (21) and a pad (22e) of the integrated circuit (22), said connecting wire being composed of a first portion (241) which connects the outer end (21e) of the antenna to a first area (251) of the intermediate connecting pad (25) and a second portion (242) which connects a second area (252) of the intermediate connecting pad (25) to the pad (22e) of the integrated circuit (22).

3. The electronic module according to one of the preceding claims, characterized in that the connection between a connecting pad (22p) of the integrated circuit (22) and at least one of the electrically-conductive tracks (21) or at least one of the connection wells is made with an aluminum wire.

4. The electronic module according to one of claims 1 to 2, characterized in that the connection between a connecting pad (22p) of the integrated circuit (22) and at least one of the electrically-conductive tracks (21) or at least one of the connection wells is made with a gold wire.

5. The electronic module according to one of claims 1 to 4, characterized in that the integrated circuit (22) is an electronic chip.

6. The electronic module according to any one of claims 1 to 5, characterized in that the antenna formed by the electrically-conductive tracks (21) has a bypass area (Zc) intended to bypass the outer end (21e) of the antenna, said bypass area (Zc) extending towards the inside of said antenna, and in that the intermediate connecting pad (25) has a complementary shape (351) to said bypass area (Zc).

7. The electronic module according to claim 6, wherein the complementary shape (351) is partially curved.

8. The electronic module according to any one of claims 6 or 7, wherein the intermediate connecting pad (25) comprises an electrically-conductive track (352) extending over said inner periphery (36) to fully surround the integrated circuit (22).

9. A method for manufacturing an electronic module (2) according to any one of claims 1 to 8, including at least the following steps of: - at least one electrically-conductive track (21) is arranged on at least one face of a substrate (20), - at least one integrated circuit (22) comprising at least one connecting pad (22p) is deposited over said substrate (20), characterized in that: - at least one intermediate connecting pad (25) configured to ensure a connection between said at least one connecting pad (22p) and said at least one electrically-conductive track (21) or a connection well (231, 232, 233) of the substrate (20) is made, so that at least one intermediate connecting pad (25) extends over at least one portion of the inner periphery (36) formed by said at least one electrically-conductive track (21), - said at least one intermediate connecting pads (25) is electrically dissociated from said at least one electrically-conductive track (21) or from said connection well (231, 232, 233), - the connection between said at least one of the intermediate connecting pads (25) and said at least one electrically-conductive track (21) or said at least one connection well (231, 232, 233) is made using a first connecting wire, and the connection between at least one of the intermediate connecting pads (25) and one of the pads (22p) of said at least one integrated circuit (22) is also made using a second connecting wire.

10. The method according to claim 9, characterized in that said electrically-conductive tracks (21) are deposited to form at least one antenna comprising a first end (21i) and a second end (21e), and a connection is made between said intermediate connecting pad (25) and at least one outer end (21e) of said antenna via a first connecting wire (241), and with at least one connecting pad (22p) of the integrated circuit (22) via a second connecting wire (242).

11. The method according to one of the claims 9 or 10, characterized in that said at least one intermediate connecting pads (25) is electrically dissociated upon creation of a central opening (26) in the substrate (20), said central opening being intended to receive said at least one integrated circuit (22).

12. The method according to one of claims 9 to 11, characterized in that the first or second connecting wire is a gold wire or an aluminum wire.

13. The method according to one of claims 9 to 12, characterized in that it further includes a step of encapsulating said electrically-conductive tracks (21), the intermediate connecting pads (25) and the integrated circuit (22) using a protective resin.