WO2000077728A1

WO2000077728A1 - Cards and method for making cards having a communication interface with and without contact

Info

Publication number: WO2000077728A1
Application number: PCT/FR2000/001489
Authority: WO
Inventors: Jean-Christophe Fidalgo; Bernard Calvas; Philippe Patrice
Original assignee: Gemplus
Priority date: 1999-06-15
Filing date: 2000-05-30
Publication date: 2000-12-21
Also published as: AU5228900A; FR2795202A1; FR2795202B1

Abstract

The invention concerns a method for making electronic devices, for instance chip cards, comprising on a support (16) at least a chip (2) and a communication interface (10, 8) connected to the chip, the communication interface including at leas an ohmic contact pad (10) and an antenna (18). The invention is characterised in that it comprises, for each or the chip, steps which consist in: a) providing a chip in the form of a very thin semiconductor (2), the chip comprising at least a first bump contact (8) designed to be connected to a corresponding ohmic contact pad (10) and at least a second bump contact (14) designed to be connected to the antenna; b) providing a support (16) comprising an antenna having at least a connection point with a second corresponding bump contact of the chip; c) producing one face of the chip at least part of an ohmic contact pad connected to a first bump contact of the chip; d) transferring said chip onto the support with the or each contact pad facing outwards opposite said support; and e) fixing the or the second bump contact(s) of the chip at the corresponding connection point(s) of the antenna. The invention also concerns a chip card produced by said technology.

Description

CARD AND METHOD FOR MANUFACTURING CARDS HAVING CONTACTLESS COMMUNICATION INTERFACE AND WITHOUT

CONTACT

The present invention relates to a card, such as a smart card, having a contact and contactless communication interface. The present invention also relates to a method of manufacturing such cards.

A smart card or the like generally comprises a support, which constitutes the body of the card, at least one chip which contains a microcircuit and a communication interface. The communication interface makes it possible to connect the various entry and exit points of the microcircuit (s) with the external environment, in particular for exchanging signals with a device such as a card reader and / or for providing a power supply for the microcircuit (s).

There are conventionally two types of communication interface:

- the type called "contact" which has contact pads around the chip, each pad being connected to an input / output of the chip and being intended to come into ohmic contact, that is to say in physical contact , with a corresponding contact element of a device placed in communication with the card, such as a card reader; and - the so-called "contactless" type which comprises an antenna, generally integrated into the card holder, having at least one of its ends connected to an input / output of the chip in order to exchange signals, and possibly supply the puce, remotely over the air from a device connected to the card. Contact type communication interfaces are very frequently used for payment cards, such as cards intended for bank transactions, in particular because of their low manufacturing cost and the fact that data communication can only be carried out when the card is physically inserted into a reader, which adds a security element.

Communication interfaces of the contactless type are however useful when it is desirable to save the user the downtime and the action necessary to insert a card into a reader. Thus, contactless cards are used in particular in electronic toll collection systems on motorways or for the controlled crossing of certain accesses. In this case, the data exchange takes place over a sufficient radius of action around the antenna of the reader equipment so that the card holder does not have to stop on the way. There are also cards provided with communication interfaces which allow both contact and contactless communication. These so-called "combined" cards (generally known by the English term "co bicard") then include ohmic contact pads and an antenna connected to one or more chips allowing versatile use, for example depending on the services used. .

The realization of the communication interface for such a combined card is relatively complex and costly, in particular because the presence of the contact pads, the configuration and size of which are governed by industrial standards, must not interfere with the conductive tracks. linked to the antenna, and vice versa. Furthermore, when the communication interface must allow contact exchange, the standards stipulate a maximum over-thickness authorized for the chip and communication interface assembly relative to the general plane of the face on which they are located. For example, the maximum excess thickness authorized by the ISO 7811 standard is 50 microns.

According to the conventional approach, the solution to reduce or avoid over-thickness consists in creating a cavity in the support of the card intended to house the chip and possibly the contact pads of the communication interface.

In addition, it is important to design processes compatible with automated tools for mass production, allowing high rates of transfer and welding of the chips on their support.

With regard to the integration of the chip into the antenna, one of the main problems to be resolved is the thickness of the assembly, to which are added the constraints of mechanical strength, reliability and manufacturing cost.

A known solution of the prior art, described in the document PCT WO-A-9607985 for making a connection between an antenna and the chip consists in forming metal bosses on two contact pads of the chip, then in connecting these bosses to the ends of an antenna wire. In this case, the antenna wire is a copper wire formed on a substrate and the bosses are applied to this antenna wire by hot compression.

However, the interconnection block thus obtained presents problems of mechanical strength and brittleness in traction of the connection. Indeed, it sometimes some mechanical stress causes the bosses to break.

In another solution known from the prior art, the connection between the antenna and the chip is made by means of conductive adhesive applied between the antenna and metallic bosses formed on two contact pads of the chip. In this case, however, a significant excess thickness appears due to the presence of the glue and the bosses. It should also be noted that smart cards only allow chips of modest dimensions to be used, since the chips used until now cannot withstand bending, being produced on relatively thick substrates. However, it is envisaged to produce on relatively flexible supports, in particular in the format of smart cards, circuits of great complexity which can integrate for example the functions of microcomputer, of memory with very large capacity, for example for the storage of audio and / or video data, etc. Such circuits involve large chips, typically greater than 10 mm in sides, which are therefore considered too fragile to be transferred to a non-rigid support. In view of these problems, the present invention provides a method of manufacturing electronic devices having on a support at least one chip and a communication interface connected to said chip, the communication interface comprising at least one ohmic contact pad and one antenna, characterized in that it comprises, for the or each chip, the steps consisting in: a) providing a chip in the form of a very thin semiconductor, said chip comprising at least a first contact pad intended to be connected to a pad of corresponding ohmic contact and at least one second contact pad intended to be connected to the antenna; b) providing a support comprising an antenna having at least one connection point; c) producing on one face of the chip at least one ohmic contact pad connected to a first corresponding pad of the chip; d) transferring said chip onto the support with the or each contact pad facing outwards with respect to said support; and e) fix the second contact (s) of the chip to the corresponding connection point (s) of the antenna.

According to a variant, the steps consist in: a) providing a chip in the form of a very thin semiconductor, said chip comprising at least a first contact pad intended to be connected to a corresponding contact pad and at least a second contact pad intended to be connected to the antenna; b) providing a support comprising an antenna having at least one connection point; c) transferring said chip onto the support; d) producing on one face of the chip at least part of a contact pad connected to a first corresponding pad of the chip; and e) attaching the second contact pad (s) of the chip to the corresponding connection point (s) of the antenna.

Advantageously, the contact area (s) is / are contained (s) entirely on the surface of said chip.

Preferably, the or each contact pad is produced by printing using an electrically conductive ink, for example using a lithographic process. According to one embodiment, the or each first contact pad has at least one contact face intended to be connected with a corresponding ohmic contact pad, the contact face being substantially in the general plane of the face of the chip receiving this contact range.

Preferably, the or each second contact pad, which can be made of aluminum, crosses the thickness of the chip and has respective faces, each being substantially in general plane with a corresponding face of the chip.

Advantageously, at least the or each connection point of the antenna is made of aluminum.

The antenna can be produced on a polymer film deposited on one face of the support, for example according to a chemical etching process.

When the or each second stud is traversing, it can be welded to the corresponding connection point of the antenna by applying welding energy through the thickness of the second stud.

This welding can be carried out by thermocompression or by ultrasound.

It is also possible to envisage an adhesive layer and interposed between the chip and its support.

The present invention also relates to an electronic device, for example a smart card, having on a support at least one chip and a communication interface connected to said chip, the communication interface comprising at least one ohmic contact pad and an antenna. , characterized in that the or each ohmic contact pad is made at least in part on a surface of said chip. Preferably, the chip comprises at least a first contact pad having at least one contact face connected to a corresponding contact pad, the contact face being substantially in the general plane of the surface of the chip comprising the pad (s) ( s) contact.

Advantageously, the chip comprises at least a second contact pad connected to a corresponding connection point of the antenna, the or each second contact pad crossing the thickness of the chip and having respective faces each being substantially of general plane d 'a corresponding face of the chip.

The or each second contact pad can be made of aluminum.

Likewise, at least the or each connection point of the antenna is made of aluminum.

According to a preferred embodiment, the antenna is produced on a polymer film deposited on one face of the support.

An adhesive layer can be interposed between the chip and its support.

The present invention advantageously implements the technology of chips made of very thin substrate, as described in particular in the patent document WO-A-9802921 in the name of the company KOPIN. This technology makes it possible in particular to have chips having a thickness equal to 10 microns, or even very significantly less than this thickness. Advantageously, at least the connection points of the antenna - and preferably the entire antenna - are formed on a surface portion of a face of the support which is in the general plane of this face. In other words, at the connection points are not formed in a cavity or other depression formed in the support.

The present invention will be better understood and the advantages which ensue from it will appear more clearly on reading the following description of a preferred embodiment, given purely by way of non-limiting example, with reference to the accompanying drawings, in which :

- Figure 1 is a partial plan view of a wafer from the so-called silicon on insulator technology used in the embodiment of the invention;

- Figure 2 is a sectional view along line II-II 'of Figure 3; - Figure 3 is a partial plan view of the wafer of Figure 1 after a step of producing ohmic contact pads on the surface of the chips;

- Figure 4 is a sectional view along line IV-IV of Figure 3; - Figure 5 is a sectional view showing the transfer operation of a chip with its ohmic contact pads on a communication interface on the surface of a support; and

- Figure 6 is a perspective view of a device, in this case a smart card, produced in accordance with the present invention.

Figure 1 is a partial view of a wafer 12 from the technology called silicon on insulator (in English SOI for "silicon on insulator"). This technology makes it possible to produce chips 2 - that is to say the active part of the microcircuit - of very great thinness.

SOI technology for obtaining chips with such dimensional characteristics is described in particular in patent document WO-A-98 02921 on behalf of the company KOPIN. Also, the manufacturing details of these chips will not be repeated for the sake of brevity.

The chips 2 are arranged in row lines on an insulating protective substrate 4, typically glass, which constitutes the body of the wafer. This insulating substrate 4 is used inter alia to protect the chips 2 which are flexible due to their great thinness (of the order of 10 microns). Each chip 2 is retained on the protective glass substrate 4 by adhesive pads 6. These adhesive pads 6 are constituted by small rectangular areas, turned at 45 ° relative to the sides of the chips 2 and placed on the respective corners of each chip , so that outside the periphery of the wafer 12 an adhesive pad 6 covers four corners joined by four different chips.

In the case under consideration, each chip is of large dimensions, their area being large enough to contain a set of ohmic contact pads of a chip card of the "contact" type, and the size and configuration of which are fixed by current industrial standards, for example the ISO 1170 standard. As will appear below, these ohmic contact pads constitute the part of the communication interface making it possible to establish a connection between the chip 2 and a reader of the contact type. For example, each chip 2 has an area of the order of 100 mm or more. Each chip 2 comprises a set of first contact pads 8 (in the example, six are arranged symmetrically in two rows of three pads) which constitute entry / exit points of the circuit contained in the chip 2 opposite from the outside. These first contact pads 8 are produced according to a so-called "boss-free" technique also known by the English term "bumpless".

As appears more clearly in FIG. 2, a characteristic of this type of stud 8 resides in the fact that it has at least one surface 8a of contact with the outside which is substantially in the general plane of at least one of the faces 2a of the chip 2.

These contact pads are distinguished from those known in the form of bosses (also called "bumps" in English terminology) which have a clear protuberance with respect to the plane of the chip, this protuberance being precisely exploited to create 1 'interconnection. In the example, each first pad 8 has a single contact face 8a, present on the face 2a of the chip 2 facing outwards vis-à-vis the protective substrate 4. This contact face 8a is substantially flush with the face 2a the chip 2. However, this contact face 8a can be slightly set back or projecting with respect to the corresponding face 2a of the chip while being considered to be situated substantially in the general plane of the chip, given the great thinness of the chip and the tolerances in the manufacturing processes.

A respective contact pad 10 is formed on each first contact pad 8 which covers the contact surface 8a. Each contact pad 10 is dimensioned and configured to constitute an area in accordance with established standards to allow the interface to be produced by ohmic contact with a contact reader. In the example, each contact pad 10 is rectangular, all six pads 10 being distributed symmetrically on the surface 2a of the chip 2 in two lines of three pads, as the shows FIG. 3. All of the contact pads 10 are completely contained within the surface of the chip 2.

Several techniques can be envisaged for producing the contact pads 10. In the example, they are printed by a screen printing process by means of an ink made electrically conductive by a charge of metallic particles, for example silver. The ink also contains an adhesive charge allowing good adhesion to the silicon surface of chip 2.

It is also possible to produce the contact pads 10 by vacuum metallization, by electrolytic deposition, by the so-called "electroless" technique or any other known method of producing bosses.

It will be noted that the contact pads 10 thus produced directly on the active surface of the chip 2 constitute what can be called "egos", or "mega bumps" in English terminology. The chip 2 also includes second contact pads 14 intended to allow interconnection with an antenna produced on one face of the support to which this chip will be transferred.

In the example, each chip 2 has two second studs 14 located near a pair of diagonally opposite corners (FIG. 1).

As shown in FIG. 4, these second studs 14 are substantially the same thickness as the chip 2 and have contact faces 14a and 14b which are flush with the respective faces 2a and 2b of the chip 2. In other words, each second stud 14 crosses the thickness of the chip 2.

Note however that, as in the case of the first pads 8, the or each contact face 14a and 14b of the second pads 14 may be slightly in withdrawal or projecting from these respective faces 2a and 2b of the chip 2 while being considered to be situated substantially in the general plane of the corresponding face 2a or 2b of the chip. Like the first pads 8, these second connection pads 14 are distinguished from the studs known in the form of bosses (also called "bumps" in English terminology) which have a clear protuberance with respect to the plane of the chip . A description will now be given of the transfer operations on a final support of the chip 2 with the printed contact pads 10.

Initially, the wafer 12 is cut into elementary assemblies each comprising a chip 2, the portion of the protective substrate 4 under the chip and the portions of adhesive pads 6 which hold the chip 2 to the substrate 4.

Then, the body of the chip 2 is separated from its portion of substrate 4 and from the adhesive pads 6 by a conventional cleavage or peeling operation.

As shown in Figures 5 and 6, the bare chip 2 is transferred to the face 16a of its support 16 which has an antenna 18 formed on this face 16a. In this transfer configuration, the contact pads 10 of the chip 2 are turned towards the outside with respect to the face 16a which receives the chip.

The antenna 18 forms a loop and has at each of its two ends a connection point 18a, positioned and configured to be brought into contact with the contact face 14b of a respective second contact 14 of the deferred chip 2, this face being turned towards the support 16. At least the connection points 18a of the antenna 18 are made of aluminum. In the embodiment, the antenna 18 is produced by an etched aluminum layer chemically on the surface of a polymer film 20 (Figure 5). The polymer film 20 is deposited on the face 16a of the support intended to carry the chip 2.

This film 20 can cover this entire face 16a of the support, or only a part of the area of the antenna 18.

The technique of chemical etching of aluminum conductive tracks on polymer film is well known, being used in particular for the manufacture of anti-theft labels affixed to over-the-counter items making it possible to trigger an alarm in the event of unauthorized crossing of a terminal control.

Of course, the antenna 18 can also be produced by any other etching technique (laser, hot stamping, etc.).

Once the contact faces 14b of the second contacts 14 are brought into contact with the corresponding connection points 18a of the antenna, a weld is made to secure the latter.

The welding is carried out by means of a thermocompression tool 20 (FIG. 5) which applies pressure to the face 14a of the second contacts 14 opposite to that 14b facing the connection points 18a of the antenna 18. To this end, the thermocompression tool 20 has a welding head 20a having a section substantially equal to or less than the surface of a second contact 14, intended to come against the surface 14a of the latter and press the second contact pad against its point of corresponding connection 18a. At the same time, the tool 20 provides thermal energy by generating vibrations through the second contact pad 14. This energy raises the temperature at the point of contact and creates the fusion between the second contact pad 14 and its connection point 18a at the level of the antenna 18.

It is noted that the second contact pad 14 and the connection point 18a, being both aluminum, are perfectly compatible with this thermocompression technique.

The thermocompression technique is in itself well known and will not be detailed here for the sake of brevity. It will be recalled that it makes it possible to produce welds at a high rate and therefore makes it possible to obtain low manufacturing cost.

As a variant, it is also possible to carry out the welding of the connections 14 and 18a by ultrasound or by laser beam according to techniques known in themselves. In these cases also, the welding energy can be applied to the face 14a of the second contact pad 14 opposite the face 14b in contact with the connection point 18a, and thus pass through the thickness of the second pad 14 Of course, it is possible to envisage making the second contact pads 14 and / or the connection points 18a of the antenna 18 in other metals or alloys as soon as they are compatible with the manufacturing techniques. and solder used.

The use of second contact pads 14 passing through and substantially without relief with respect to the respective faces 2a and 2b of the substrate 2, that is to say without boss, makes it possible in particular to produce automated welds according to the "automated welding" technique. on tape without boss ", also known by the Anglo-Saxon term of" bumpless tape automatic bonding "or" bumpless TAB ". This technique allows soldering at very high rates by mounting the chips 2 on a strip which is scrolled in front the welding tool 20, the supports 16 also being made to travel in synchronism with the rhythm of the welds.

The welding operation of the second pads 14 on the points 18a of connection of the antenna 18 also serves to fix the chip 2 on its support 16.

If necessary, an adhesive layer may be provided interposed between the support 16 and the face 2b of the chip 2 opposite the support. It is also possible to provide that the film 20 on which the antenna 18 is formed passes under the entire surface of the chip 2 and contributes to its adhesion to the support.

Finally, at least the parts of the surface 2a of the chip 2 which are not covered by the contact pads 10 can be protected by a protective layer (not shown). This protective layer can be produced in the form of a film or varnish deposited by any technique, for example by means of spraying.

In the example, the first pads 8 and second pads 14 are not connected to common points of the chip circuit. However, it is entirely possible to make a common connection to a point on the circuit by means of a first pad 8 and a second pad 14, depending on the application envisaged.

Furthermore, it is possible to use also for the first pads 8 through studs, as with the second pads 14. As regards the contact pads 10, these can have other configurations and be in different numbers according to the standards followed and the ohmic connections to be established with the chip. These contact areas can possibly be extended beyond the limits of the chip by printing or metallization on the support or on a film affixed to the support.

Furthermore, the order of carrying out the steps described is not imperative. By way of example, it is also possible to envisage printing the contact pads 10 only after the chip has been transferred, this solution being possible in particular if it is necessary to extend the connection pads beyond the chip limits. In a variant of the embodiment just described, one could envisage the postponement of the chip 2 in a cavity formed in the body of the support 16 to compensate for the excess thickness.

Finally, it will be noted that the second pads 14 can be connected to elements within the support other than the terminals of an antenna, these pads can also be used in particular to interconnect the chip with tracks connected to one or more of : one or more other chips, passive components (resistors, inductors, capacitors, etc.), a power source (for example a solar cell), a

^• display, computer interface or other connection elements.

Of course, the field of the present invention extends to all applications requiring a very thin chip transfer and provided with contact pads on a surface of a support, the latter possibly being not only flexible (film, sheet, plastic card, etc.) but also rigid.

Claims

1. Method for manufacturing electronic devices having on a support (16) at least one chip (2) and a communication interface (10, 18) connected to said chip, the communication interface comprising at least one ohmic contact pad (10) and an antenna (18), characterized in that it comprises, for the or each chip (2), the steps consisting in: a) providing a chip in the form of a very thin semiconductor (2), said chip comprising at least a first contact pad (8) intended to be connected to a corresponding ohmic contact pad (10) and at least a second contact pad (14) intended to be connected to the antenna (18); b) providing a support (16) comprising an antenna having at least one connection point (18a); c) producing on one face (2a) of the chip at least one ohmic contact pad connected to a first corresponding pad of the chip; d) transferring said chip onto the support with the or each contact pad facing outwards with respect to said support; and e) attaching the second contact pad (s) of the chip to the corresponding connection point (s) of the antenna.

2. Method for manufacturing electronic devices having on a support (16) at least one chip (2) and a communication interface (10, 18) connected to said chip, the communication interface comprising at least one ohmic contact pad (10) and an antenna (18), characterized in that it comprises, for the or each chip, the steps consisting in: a) providing a chip in the form of a very thin semiconductor (2), said chip comprising at least one first contact pad (8) intended to be connected to a corresponding contact pad (10) and at least one second contact pad (14) intended to be connected to the antenna (18); b) providing a support (16) comprising an antenna having at least one connection point (18a); c) transferring said chip onto the support; d) producing on one face of the chip at least part of a contact pad connected to a first corresponding pad of the chip; e) fix the second contact pad (s) of the chip to the corresponding connection point (s) of the antenna.

3. Method according to any one of claims 1 or 2, characterized in that the contact area (s) (10) is / are contained (s) integrally on the surface of said chip (2).

4. Method according to any one of claims 1 to 3, characterized in that the or each contact pad (10) is produced by printing by means of an electrically conductive ink.

5. Method according to claim 4, characterized in that the or each contact pad (10) is printed by a lithographic process.

6. Method according to any one of claims 1 to 5, characterized in that the or each first contact pad (8) has at least one contact face (8a) intended to be connected with a corresponding ohmic contact pad ( 10), said contact face being substantially in the general plane of the face ((2a) of the chip (2) receiving this contact pad.

7. Method according to any one of claims 1 to 6, characterized in that the or each second contact pad (14) crosses the thickness of said chip (2) and has respective faces (14a, 14b) each being substantially of general plan of a corresponding face (2a, 2b) of the chip (2).

8. Method according to any one of claims 1 to 7, characterized in that the or each second contact pad (14) is made of aluminum.

9. Method according to any one of claims 1 to 8, characterized in that at least the or each connection point (18a) of the antenna (18) is made of aluminum.

10. Method according to any one of claims 1 to 9, characterized in that the antenna (18) is produced on a polymer film (20) deposited on one face (16a) of the support.

11. Method according to any one of claims 1 to 10, characterized in that the antenna (18) is produced by a chemical etching process.

12. Method according to any one of claims 7 to 11, characterized in that the or each second stud (14) is welded to the corresponding connection point (18a) of the antenna (18) by application of a welding energy through the thickness of the second stud.

13. Method according to claim 12, characterized in that the or each second stud (14) is welded by thermocompression.

14. Method according to claim 12, characterized in that the or each second stud (14) is welded by ultrasound.

15. Method according to any one of claims 1 to 14, characterized in that an adhesive layer is interposed between said chip (2) and its support (16).

16. Method according to any one of claims 1 to 15, characterized in that at least the connection points (18a) of the antenna (18) are formed on a surface portion of a face (16a) of the support (16) which is in the general plane of this face.

17. Electronic device, for example a smart card, having on a support (16) at least one chip (2) and a communication interface (10, 18) connected to said chip, the communication interface comprising at least one ohmic contact pad (10) and an antenna (18), characterized in that the or each ohmic contact pad is made at least in part on a surface of said chip.

18. Device according to claim 17, characterized in that the chip (2) comprises at least a first contact pad (8) having at least one contact face (8a) connected to a corresponding contact pad (10), said contact face being substantially in the general plane of the surface of the chip comprising the contact area (s).

19. Device according to claim 17 or 18, characterized in that the chip (2) comprises at least a second contact pad (14) connected to a corresponding connection point (18a) of the antenna (18), the or each second contact pad crossing the thickness of said chip and having respective faces (14a, 14b) each being substantially of general plan of a corresponding face (2a, 2b) of the chip.

20. Device according to any one of claims 17 to 19, characterized in that the or each second contact pad (14) is made of aluminum.

21. Device according to any one of claims 17 to 20, characterized in that at least the or each connection point (18a) of the antenna (18) is made of aluminum.

22. Device according to any one of claims 17 to 21, characterized in that the antenna (18) is produced on a polymer film (20) deposited on one face (16a) of the support (16).

23. Device according to any one of claims 17 to 22, characterized in that an adhesive layer is interposed between said chip (2) and its support (16).

24. Device according to any one of claims 17 to 23, characterized in that at least the connection points (18a) of the antenna (18) are formed on a surface portion of a face (16a) of the support (16) which is in the general plane of this face.