NO178089B - Method of manufacturing an electronic memory card - Google Patents

Abstract

In order to produce the card body from a plastic material, the electronic module (14) whose covering (50) has an undercut (54), is placed in a mould (60,62). The module is held in place by suction (72). The plastic material is injected into the mould, thereby producing a moulding around the electronic module. <IMAGE>

Description

The present invention relates to a method for producing cards with memory, in particular an electronic memory.

Cards with memory mainly consist of a card body made of a plastic material, together with a memory module. For cards with electronic memory, the memory module is an electrical module, essentially consisting of a semiconductor chip with an integrated circuit together with a printed circuit on which the semiconductor chip is attached, and which serves as external connection contacts. The electronics module is attached to the card body in such a way that the electrical contact fingers lie flush with one of the main sides of the card body.

The card body is generally designed from a rectangular parallelepiped whose thickness is small in comparison with the other dimensions of the body. The edges of the card body form reference points for placing the card in a card reader so that it is ensured that the contact fingers on the card come into electrical contact with a contact unit in the card reader.

Currently, there are two main techniques for making the board body and for attaching the electronics module to it. In the first technique, the card body is made by heat rolling a plurality of sheets of a plastic material, for example PVC, to form a laminated structure. The electronics module is put in place before the sheets of plastic material are stacked and before they are rolled. After they have been rolled, the electronics module is fixed in place in the card body. This method has the advantage that you simultaneously make the board body and plant the electronics module. However, the process is difficult, requiring the circumference of the card body to be machined to tolerances.

The second technique consists of making the card body in a first step, machining a recess in the card body to receive the electronics module, and then gluing the electronics module into the cavity. Machining such a card body is a difficult, and therefore expensive, operation, since one must have very precise dimensions to ensure that the electronics module is precisely positioned in relation to the edges of the card and in relation to the main side of the card body which is flush with the electrical contact fingers . In addition, fixing, for example gluing, the electronics module in the card body is an additional step.

Another method for producing cards is known from Japanese publication JP-A-60,146,383, where a resin is introduced into the cavity of a mold through an introduction opening, and where the mold is also provided with an outflow opening. The resin is cured using an electron beam.

It should be noted that a card body must also satisfy other highly detailed specifications regarding the quality of the surface condition, and its properties to resist bending, both in the longitudinal and transverse directions of the card body. Furthermore, the card body must not allow the build-up of electrostatic charges. An aim of the present invention is to produce a method for making a card with memory, in particular a card with an electrical memory, which allows a reduction of the costs of manufacturing the card body, while at the same time allowing the electronic module to be fixed in the card body and satisfying the above-mentioned specifications.

This aim is achieved, according to the present invention, by a method for producing an electronic memory card which comprises an electronic storage module with external contact fingers, a semi-conducting chip attached to the rear surfaces of the contacts, devices for connecting the terminals of the chip and the contact fingers, and a covering material for the chip and a card body, where the method is characterized by the fact that it comprises the following steps: an electronic storage module is provided which also comprises a fastening part designed to fix the module in the card body by positive engagement and/or by physiochemical bonding;

said electronic storage module is placed in an injection mould, whose inner cavity defines the shape of the card body, and the electronic module is held in such a way that the external contact fingers are pressed against a wall of the cavity by means of devices attached to the mould;

a thermoplastic material selected from the group comprising acrylonitrile-butadiene-styrene, polystyrene, propylene and polyamine 11, is injected under heating and under pressure into the cavity of the mold in such a way that said plastic material fills up the entire cavity that is not occupied by the module, and

the component produced in this way is then removed from the mold.

In a preferred embodiment, the attachment part is a special form of the cover material.

It is also preferred that the card body has two main surfaces, where the electrical contact fingers are flush with one of the main faces, and the electronics module is placed in the mold so that the external contact fingers are placed against the mold wall which defines one of the card body's main surfaces, and that a recess is created between the mold's wall and the external contact fingers to hold the module against the wall.

It must be understood that according to the invention the card body is molded directly over the storage module. The card body is manufactured and the module is implanted in the card body in a single operation. In addition, since the module can be placed very precisely inside the mold, the module is also placed with great accuracy in the card body.

The invention can be better understood by reading the following description of several embodiments of the invention, given through non-limiting examples. The description refers to the following drawings, where: Fig. 1 is a ground plan of an electronic memory card according to the invention; Fig. 2 is a vertical section through an electronics module which can be used in the invention; Fig. 3 is a simplified section through a first type of mold for carrying out the invention; Fig. 3a is a section along a line A-A in figure 3, and shows a first variation of the shape of Figure 3; Fig. 3b shows a section along line A-A in figure 3 and shows another variation of the shape in figure 3; Fig. 4 shows a simplified section through another type of shape

for carrying out the invention;

Fig. 5 shows part of a vertical section through a

electronic memory card according to the invention;

Fig. 6 is a plan view of a third type of mold for making a

plurality of cards simultaneously, and

Fig. 7 is a vertical section along the line VII-VII in Fig. 6. Fig. 1 shows a plan view of part of an electronics memory card 10. The card 10 comprises a body 12 made of a plastic material together with one electronics module 14 which is

represented in Figure 1 only with its outer electrical contact fingers 16 to 30, which are placed on an insulating support. As is well known in the art, the contact fingers 16 to 30 are intended to come into electrical contact with a contact unit in a card reader

which is used in connection with such cards.

Figure 2 shows an electronics module 14 which is well suited for carrying out the invention. The module 14 comprises an insulating support 32 with outer electrical contact fingers formed on one side 32a. Figure 2 shows contact fingers 18, 28 and 16. The contact fingers are separated from each other by etched zones such as 34. The contact fingers and the insulating support 32 additionally have a number of holes, such as 36, the function of which is explained below. The other side 32b of the insulating support 32 also includes metallization 38 and 40.

A semiconductor chip 42 is attached to the central metallization 38 by means of a conductive adhesive material. The metallization 38 and the metallizations 40 are electrically connected to the contact fingers 16 to 30 via a hole 44 through the insulating support material 32. In addition, each of the terminals 36 on the semiconductor chip 42 is connected to a corresponding metallization 40 by means of a wire 48.

The chip 42 and the wires 48 are embedded in an insulating covering material 50 which adheres well to the metallizations 40, to the chip 42 and to the wires 48. The covering material can be a thermosetting resin material. In addition, the cover material 50 is molded or machined so as to produce a substantially flat bottom 52 which is parallel to the insulating support material 32. The side walls 54 of the cover material slope at an angle less than 90° with the side 32b of the insulating support material 32 which are not covered with covering material.

A first embodiment of a card and a first method for attaching the electronics module in the card body according to the invention will now be described with reference to Figure 3. The form essentially consists of a fixed front part 60 and a removable back part 62, where these two parts form a cavity in which the card body is formed. More precisely, the front part 60 has a first flat wall 64 which defines one of the main sides of the card body, and a side wall 66 which defines the edges of the card body.

The second part 62 of the mold defines the other main side of the card body. The side wall 66 bg the advantage 60 of the mold is equipped with an injection channel 68 for injecting the plastic material from which the card body is produced. The wall 64 is equipped with a device for holding the electronics module

14 quietly while the plastic material is injected into the mold. In this first embodiment of the invention, this device consists of knobs 70 that protrude from the inside 64 of the mold, and a suction system consisting of a suction nozzle 72 in connection with a vacuum pump 74. The knobs 70 have the same physical distribution as the holes 36 through the electronics module 14 In addition, the suction nozzle 72 is opened out into the part of the wall 64 which is surrounded by the knobs 70. A card according to the first embodiment of the invention is made as follows: when the mold is open, the electronics module is placed in place so that the knobs 70 go through the holes 3 6 into the metallizations 16 to 30 on the module. The vacuum pump 70 is switched on. The module 14 is thus held against the wall 64 of the mold in all three directions, and is held in place by the cooperation between the knobs 70 and the holes 36. The rear part 62 of the mold is then put in place on the advantage 60. The plastic material is then injected via the injection channel 68 The plastic material fills the entire cavity which is limited by the mold and which is not occupied by the electronics module 14. The card is then removed from the mold.

Figure 5 shows part of a vertical section through a card produced by an embodiment of the above-mentioned method. It must first be emphasized that because of the special shape of the weight material 50 and because the card body is made by molding over the electronics module, the electronics module is mechanically anchored in the card body. Consequently, the module is very well fixed in the card body 12. Furthermore, since the outer surface of the electronics module is pressed against the wall 64 of the mold, no plastic material gets on the electrical contact fingers 16 to 30. In addition, since the perimeter 76 of the insulating support material 32 and the contact fingers 16 to 30 serve to limit the filling of the mold cavity with plastic material, the outer aspect of the card, where the outer surface of the electronics module runs into the corresponding main surface of the card body, is particularly satisfactory.

Preferably, as shown in figure 3a, the injection channel 68 opens into a "corner" 63 of the mold defining a corner of the card body which has the shape of a right angle, while the other "corners" 65, 67 and 69 are rounded. After the corner 63 of the card body is cut off from the inlet, all traces of the injection molding can be removed from it. It is also possible to have a plurality of injection channels opening into respective "corners" of the mold.

Figure 3b shows another embodiment of the device for placing and holding the electronics module in the mold. Instead of the knobs 70, the wall 64 of the mold also has four projecting parts 100 to 106 which correspond to the four corners of the insulating support for the electronics module. The suction nozzle 72 opens out in the part of the wall 64 which is limited by the protruding elements 100 to 106. As shown in Figure 3b, the suction nozzle can end in a plurality of openings 108, each of which corresponds to one of the contact fingers on the electronics module. Instead of having four parts 100 to 106, it is also possible to have a complete rectangular frame projecting from the face 64 of the module.

There are naturally other types of electronic modules that could be used. One could, for example, use the type described in French patent application no. 2,547,440, 2,555,780, or 2,579,799. The module could be of the "leader-frame" type. Such electronic modules are described in European patent application no. 87/4016797 of 21 July 1987. Such a module does not include an insulating support. The semiconductor chip is attached directly to a conductive element that forms one of the contact fingers on the memory card, while the terminals on the chip are connected by conductive wires to other conductive elements that form the other contact fingers on the card.

Instead of the electronics module having an anchoring element formed by the special external shape of the chip's covering material, it is possible that the module has a part to attach it to the card body when the card is made, by being molded over it. The electronics module can, for example, be of the type shown in figure 2, but without the cover material 50. The fastening part of the electronics module is then formed by all the unevenness in the electronics module, including the connection lines 48 which are located on the side of the electronics module that does not include the outer contact fingers 16, 18. It is also possible to improve the attachment properties for the electronics module in relation to the card body, for example by surface treatment of the non-metallized parts of the module's insulating support 32, where there is such a support. It is also possible to make small holes through the module's support material, regardless of whether the support is made of insulating or conductive material, to improve the attachment by allowing the injected material to pass through the holes. It is also possible to carry out physio-chemical fastening, or to combine this type of fastening with mechanical fastening or anchoring of the type described above. Physiochemical attachment can be a consequence of an appropriate choice of the injected material and the materials from which the various parts of the electronics module are made, especially the insulating support material. It is also possible to carry out a chemical surface treatment on part of the electronics module, for example an insulating support, to improve physiochemical

fastening during the casting operation.

It can be seen from the present patent application that the expression "fastening part" of the electronic part does not only refer to the special form of the module's covering material which enables the module to be anchored in the card body, but that it also covers the different layouts or combinations of layouts as described above and which all seek to secure the electronics module in the card body when the card body is molded.

In the above description, the card has only one electronics module. The method according to the invention can be used to make a card with a plurality of independent modules. In this case, the mold is equipped with as many fasteners (knobs 70, suction nozzles 72) as there are modules, and the electrical contact fingers on the modules can be flush with one or the other of the two main sides of the card.

Figure 4 shows another type of mold that can be used to carry out the method according to the invention, and which further improves the holding of the electronics module at the beginning of the injection of the plastic material into the mold.

The shape as shown in Figure 4 has a fixed advantage 60', which is identical to the advantage 60 of the shape in Figure 3. The various items relating to the advantage 60' are thus given the same references as in Figure 3 together with a "marked" symbol . The rear part of the mold 80 comprises a first plate 82 whose circumference 82a is intended to be pressed against the surface 60'a of the front part of the mold 60', together with another surface 84 which is a movable plate. The movable plate 84 can be displaced relative to the plate 82, while being constrained to remain exactly parallel to the plate 64' by the front edge 60. To do this, the rear side 84a of the plate 84 is provided with guides 68 which can slide with very little clearance in the bearings 88, attached to the plate 82, The plate 84 is of such a size that its edge 84b slides along the side wall 66' of the advantage 60'. Matching springs 90 force the plate 84 away from the plate 82 to a distance limited by the supports 92 attached to the rods 86.

A card with memory is made using the form in figure 4 as follows. The back side of the mold 80 is removed, and the electronics module 14 is placed in place against the wall 64' as described above with reference to figure 3. The back side 80 is attached to the front side 64' of the mold. The plate 84 abuts the surface 52 of the cover material 50 on the electronics module 14. The springs 90 are calibrated so that in this position they are already partially compressed. The biasing of the springs 90 further improves the manner in which the electronics module is pressed against the mold wall 64'. A plastic material is then injected into the mold via the injection channel 68'. Initially, due to the bias in the springs 90, the plate 84 is held still, pressed against the module surface 52, and the plastic material fills the space around the module 14 as limited by the surface 84 and the mold advantage 60'. This position continues until the pressure of the plastic material becomes greater than the pretension of the springs 90. Then the plastic material gradually pushes the plate 84 against the compression of the springs 90, and the plate 84 is no longer in contact with the module 14. However, the plastic material now completely surrounds the electronics module 14 which helps hold it against the wall 64'. The plate 84 is forced against the springs by the plastic material until it comes into contact with the mechanical supports 96 which are attached to the plate 82. This position is determined so that the card body obtained in this way has the desired thickness after shrinking. The injection is now stopped, and the back part 82 is removed so that the card can be pulled out of the mold. This produces a card which is identical to that shown in figure 5. The shape of figure 4 can naturally include the variations illustrated in figures 3a and 3b.

The plastic material used to make the short body by injection molding can be an acrylonitrile butadiene styrene (ABS), and can be other similar types of plastic material. If ABS is used, the material is injected at a temperature between 180°C and 280°C and preferably between 220°C and 260°C. The mold is kept at a temperature of between 5°C and 100°C, preferably between 10°C and 50°C.

Other suitable thermoplastic materials can also be used, including polystyrene, polypropylene and polyamine 11.

As shown in Figure 5, a magnetic track 112 can be attached to the back 110 of the card body, for example by heat pressing. It should be emphasized that the method for producing cards according to the invention is particularly suitable for installing such a track. The part of the card body 12b, located between the electronics module and the back 110, is very stable, despite the fact that it has reduced thickness, when it is cast directly over the module's surface 52. Furthermore, the material used is well suited to embossing data on one of the main pages of the card body.

Reference is now made to Figures 6 and 7 to describe an embodiment of the form suitable for obtaining a plurality of cards simultaneously.

Figure 6 shows the front part 160 of the mold which comprises a majority of mold spaces. The part 160 of the mold has four mold spaces 162, 164, 166 and 168 which define the bodies for four cards which are produced simultaneously. An electronics module 14 is placed in each of the mold spaces 162 to 168 using one of the techniques described with reference to figures 3 to 3b. The mold spaces 162 to 168 are separated from each other by protruding parts 170 to 176. As shown in Figure 6, the protruding parts 170 to 176 do not separate the mold parts completely from each other, but leave channels that keep the mold spaces in connection with each other. There is a central channel 178 that interconnects all four mold spaces, and there are end channels 180 to 186 that interconnect adjacent grades near the mold leading edge 160. As shown in Figure 7, channels 178 to 186 are shallower. than the mold spaces 162 to 168. The channels could naturally have the same depth as the mold spaces. There are two ways in which the material can be injected into the mold. Either the injection takes place through a plurality of points 188 to 194 where each injection point opens out to one of the channels 178 to 186, or surface injection is carried out via a side opening 196 which opens out to the channel 182.

After opening the mold, you get a piece consisting of four cards corresponding respectively to the mold spaces 162 to 168, where the cards are connected by "bridges" that correspond to the plastic material that has filled the channels 178 to 186.

The fact that you get four cards that are mechanically connected to each other so that their relative position is very accurate is in itself very advantageous for subsequent offset printing on the card bodies. The printing can then take place at the same time and, in addition, it is easier to handle larger parts for placement on the printing machine.

To separate the cards from each other, the bridges must be cut. This operation is not particularly difficult, as the bridges are attached to the card bodies at their corners, i.e. the non-functional points on the card body. In addition, the inlets to the injection points 188 to 196 which open to the bridges are removed at the same time as the bridges.

Claims (12)

1. Method for manufacturing an electronic memory card comprising an electronic storage module (14) with external contact fingers (16-30), a semi-conducting chip (42) attached to the rear surfaces of the said contacts, devices (48) for connecting the chip's terminals (46 ) and the contact fingers, and a covering material (50) for the chip and a card body (12), characterized in that it comprises the following steps: an electronic storage module (14) is provided which also comprises a fastening part (50) designed to fasten the module in the card body (12) by positive engagement and/or by physiochemical bonding; the aforementioned electronic storage module (14) is placed in an injection mold (60, 62, 62', 80), whose inner cavity defines the shape of the card body, and the electronic module is held in such a way that the external contact fingers (16-30) are pressed against a wall (64, 64') in the cavity by means of devices (70, 72, 100-108) attached to the mold; a thermoplastic material selected from the group comprising acrylonitrile-butadiene-styrene, polystyrene, propylene and polyamine 11, is injected under heating and under pressure into the cavity of the mold in such a way that said plastic material fills up the entire cavity that is not occupied by the module, and the component produced in this way is then removed from the mold. 2. Method according to claim 1, characterized in that the aforementioned fastening part consists of a special form of the cover material (50). 3. Method according to claim 1, where the short body (12) has two main surfaces, with the electrical contact fingers (16-30) lying flush with one of these main surfaces, characterized in that the electronic storage module (14) is placed in the mold so that the external contact fingers are placed against the wall (64) of the mold which defines one of the main surfaces of the short body (12), and that a recess (70) is created between said wall (64) of the mold and the external contact fingers to hold the module against the wall. 4. Method according to claim 2, characterized in that the contact fingers (16-30) are provided with a number of holes (36) for cooperation with pins (70) which protrude beyond the mold wall (64) against which the electronic module is held. 5. Method according to claim 2, where the electronic module has an access surface comprising the outer, mainly rectangular fingers, characterized in that the mold wall (64), on which the module is placed, comprises a projecting part (100-106) which at least partially surrounds the access surface of the module. 6. Method according to claim 1, where the card body comprises two mainly rectangular main surfaces, characterized in that the plastic material is injected (68) into a part of the mold (62) which defines a "corner" of the card body (12). 7. Method according to claim 1, characterized in that after the said component has been removed from the mould, a magnetic track (112) is attached to one of the main floats (110) on the card body. 8. Method according to claim 1, characterized in that after the component has been removed from the mold, data is marked on one of the main rafts on the card body by embossing in the plastic material. 9. Method according to claim 1, characterized in that the plastic material is selected from the group comprising acrylonitrile-butadiene-styrene, polystyrene, polypropylene and polyamine 11. 10. Method for producing a quantity of electronic memory cards, according to claim 1, characterized in that the mold (160) comprises a plurality of cavities (162-168), where each cavity corresponds to the shape to be given to a card body, and passages (170-176) for connecting the said cavities with each other, and that an electronic storage module (14) is placed in each cavity in the mold and these are held in position in such a way that the access surface of the electronic module (14) is pressed against a wall in the mold, further that the thermoplastic material is introduced into the mold (160) in such a way way that the plastic material occupies the entire space corresponding to the part of the cavities that are not occupied by the aforementioned electronic storage modules and the aforementioned passages, and that the component produced in this way is then removed from the mould. 11. Method according to claim 10, characterized in that the thermoplastic material is introduced into the mold (160) at right angles (188) with at least some of the passages (170-176). 12. Method according to claim 10 or 11, characterized in that the thermoplastic material is selected from the group comprising acrylonitrile-butadiene-styrene, polystyrene, polypropylene and polyamine 11.