Manufacturing process for memory cards, and cards obtained by this process.

p0001The present invention relates to a memory card manufacturing process including electronic and cards obtained by implementing the method.

p0002Memory cards essentially comprise a card body which is generally made of a plastic material and a memory module. In the case of electronic memory cards the memory module is an electronic module essentially comprising a semiconductor wafer or "chip" in which is formed an integrated circuit and a circuit element printed on which is fixed the chip or the like and which defines external electrical contact tabs. The electronic module is fixed in the card body such that the electrical contact pads flush with one of the main faces of the card body.

p0003The card body has the shape of a rectangular parallelepiped whose thickness should be less than 1 mm, which is defined by ISO 7810. The edges of the card body are a reference for positioning the card in the reader cards so that the card contact pads come into electrical contact with the connector of the card reader.

p0004We must add that the card body must also meet other requirements regarding the quality of the surface condition and the specific flexural strength properties both in the longitudinal direction of the card body that according to its transverse direction and in torsion. These specifications are defined by the ISO standard (mentioned above). Furthermore it is necessary that the card body is not conducive to storing electrostatic charges.

p0005To solve this problem have been proposed in the French patent application FR-A-2609821 published July 22, 1988 to make the card in an injection molding process which comprises the following steps:    There is provided a memory module having an access face and at least one anchoring element,    Placing said module in a mold and held in place such that the access face of the memory module is disposed against a wall of the mold,    Is introduced into a mold so that the plastic material plastic material occupies all of the space bounded by the walls of the mold not occupied by said storage module, and    the piece thus produced is unmolded.

p0006Another problem with the manufacture of smart cards is the realization of graphic elements that generally includes at least one of the main faces of the card body, these graphics can be alphanumeric information or drawings for decorative purposes.

p0007When the graphic element has a certain complexity or by the shape of the path or the nature of color shades to get the graphics printing step, by screen printing or offset printing, may lead to failure especially if it is very demanding on the quality of graphics and colors. If unsuccessful, it must resolve to discard the cards the graphics quality is deemed insufficient. This means that the costs in material, components and machining steps for manufacturing the card before the graphics of the manufacturing step are lost. These costs are particularly high if the realization of graphics occurs when electronic module has already been implanted in the body of the card. This occurs particularly but not exclusively, when the card is manufactured by molding the body of the card directly on the electronic module according to the technique described in the French patent application FR-A-2609821 already cited.

p0008JP-A-60 189586 describes a method for making electronic memory cards of unspecified type in which the electronic modules are fixed on a support sheet. The portion of the sheet having an electronic module is introduced into a mold by transfer and after the molding operation the sheet is cut to the dimensions of the card body.

p0009To overcome these disadvantages an object of the invention is to provide a card making method, in particular smart card, wherein the graphics of the manufacturing step of the card bodies can in itself result in the rejection from the menu.

p0010An object of the invention is to provide an embodiment of a memory card including electronic, by overmoulding of the card body on the memory module, which enables, if desired, to achieve graphic elements in particularly advantageous economic conditions.

p0011To achieve this object, according to the invention, the method of producing an ISO type memory card comprising a card body having a thickness less than 1 mm having two parallel major faces each other and a memory module having a access face disposed in the first of said major faces of the card body which is characterized in that it comprises the following steps:    There is provided an injection mold whose imprint defines the outer shape of said card,    Providing a substrate element,    It provides a memory module having an access face    said memory pack is fixed by its access face on one side of the support member,    Placing said support member in said mold so that its periphery is secured to said mold,    in said mold a plastic material is injected so that it fills said mold cavity and said module is surrounded by said material,    Demoulding the part thus obtained and is separated from said workpiece support member, whereby said module is inserted in said body, and    After demoulding, a memory card is obtained having a card body with its final shape and wherein the electronic module is already implanted.

p0012According to a preferred mode of implementation of the method for simultaneously performing graphic elements on the first main face of the card body, this support member, on the side on which is fixed the memory module of the printing elements, and during injection of the plastic material in the mold said printing elements adhere to the face of the volume of injected material in contact with the support element, whereby a memory card is obtained comprising graphic elements on the first main face of the card body.

p0013In any case the invention will be better understood on reading the following description of several embodiments of the invention given as non-limiting examples. The description refers to the accompanying drawings in which:<ul><li>Figure 1 is a sectional view of a printing medium usable element in said invention,</li><li>Figure 2 is a sectional view of the support element provided with electronic modules,</li><li>Figure 3 is a vertical sectional view of a first type of mold used for producing an electronic memory card,</li><li>Figure 4 is a top view of an electronic memory card, and</li><li>Figure 5 is a vertical sectional view of a second type of mold used for producing an electronic memory card.</li></ul>

p0014Before explaining in detail all of the invention will be described with reference to Figure 1, a support element usable for more than achieve the desired graphics.

p0015The support member, designated 10, comprises a support of a plastic material. The support 12 is preferably made of polyester and has a thickness of about 25 micrometers. On this support 12 which acts as a mechanical support are made later for printing elements to achieve the desired graphics. For each printing element, there is a release layer 14, a decorative layer 16 formed by pigments, optionally, a lacquer layer 18, and an adhesive layer 20 whose thickness is of the order of 1 to 2 micrometers.

p0016On one sheet support 12 can carry a large number of identical patterns. Such a product is available from the German company Leonard Kurz GmbH.

p0017Referring now to Figures 2 and 3 will be described a first embodiment of electronic memory cards according to the invention.

p0018One starts with a support member 10 which includes a plurality of identical patterns, each pattern corresponding to the entire graphics to be formed on one of the body of the card faces. In Figure 2 the units A has been shown and B. Each pattern is separated from neighboring patterns with a blank whose use will be explained later.

p00194 shows a card body 30 made according to the invention. In the visible main face of the card body the electronic module 32 is shown which only the external tabs electrical contact 34 are visible. Also shown in the areas 36 of the card body which comprise a graphic. The zone 36 leaves free the portion of the face of the card body 30 occupied by the external pads 34 of electrical contact.

p0020Returning to Figure 2, it is seen that, for each pattern, the area where the graphics 36 are formed leaves the bare portion 38 of plastic support 12 should go where the electronic module 32, when the card is complete .

p0021The electronic module 32 includes a lead frame or a printed-circuit element on which are formed external pads 34, a semi conductor chip 40 fixed on the circuit board or the lead frame, the son conductors 42 that connect the terminals of the wafer 40 the contact pads 34 and a coating material 44 which surrounds the wafer 40 and son 42. a module 32 is bonded to the support 12 at each location 38, such that each pattern comprises a module.

p0022As shown in Figure 2, the external face of the external contact pads is directly bonded to the support 12.

p0023This produces a strip formed by the support 12 which has on one of its faces a plurality of patterns (A, B ..) each unit comprising an electronic module 32.

p0024In the following step is carried out the card body by injection molding of a plastic material which is preferably of ABS (acrylonitrile-styrene butadière). Figure 3 shows the mold used. It comprises a fixed part 50 and a movable portion 52. These two portions define a cavity 53 that gives the outer shape of the card body. The fixed portion 50 defines by its inner wall 54 a of the main faces of the card body. The movable portion 52 defines by its inner wall 56 of the second main face of the card body and the inner wall 58 portion of the card body. The fixed 50 and movable portions 52 each have a bearing surface 60 and 62, these two bearing surfaces normally being in mutual contact when the mold is closed.

p0025The mold being open, the band formed by the support 12 is placed between the fixed part 50 and movable part 52 of the mold. The tape is positioned relative to the footprint 53 so that the graphics 16 carried by the support 12 and, consequently, the electronic module 32 are perfectly positioned relative to the side wall 58 of the cavity, that is to say with respect to the portion of the card body which will be realized. Then the mold is closed. The support 12 is clamped between the bearing surfaces 60 and 62 of the two mold parts in the area D of the support 12 which surrounds a pattern. Then proceeds to the injection of plastic material into the cavity 53 by the injection nozzle 64, the ABS is preferably injected at a temperature between 220 ° C and 280 ° C .. Preferably the nozzle 64 is disposed at the center of the wall 56 of the movable part 52. the plastics material fills the cavity 53 by plating the support 12 against the inner wall 54 of the mold. The plastic material surrounds the electronic module 32, except for its face bonded to the support 12 and is in contact with the graphic 16. Under the effect of pressure and temperature, decorative elements 16 are fixed on the corresponding face of the volume of plastic material tends to separate from the support 12. This is achieved by activation of the adhesive layer 20 and release layer 14.

p0026If the electronic module 32 has a sufficiently reduced thickness relative to the thickness of the card, it is possible to provide that the injection nozzle opens 64 in the face 56 of the mold, compared with the electronic module. One can also provide a plurality of injection nozzles. Also it is possible to dispose of the injection nozzles in the side face 58 of the mold cavity. Of preference you then the nozzles are arranged in some "corners" of the mold cavity.

p0027After opening the mold card body is unmolded inserré in which the electronic module 32 and includes the graphic 36 desired on its main face.

p0028It is understood that the support 12 has a dual role, it allows the realization of graphics, and it ensures the precise positioning of the electronic module in relation to the mold cavity and thus relative to the card body. In addition the module's external pads being bonded to the support 12, they are protected against a possible rise of the injection material that might tend to cover them.

p0029The support 12 that bears more or electronic module or graphics remain in the mold after removal of the card.

p00305 shows a mold usable alternative to produce an electronic memory card having graphical elements on its two main faces. The mold is formed in three parts. A first part 70, mobile, comprises the portion 72 of the mold cavity that defines the first main face of the card body.

p0031A second part 74, movable part 76 includes the imprint of the mold which defines the second main face of the card body. A third portion 78, fixed, which is sandwiched between the portions 70 and 74 of the mold when the latter is closed, comprises the portion 80 of the imprint that defines the edge or the edge of the card body. The portion 78 of the mold has, for example, two injection nozzles 82 and 84.

p0032The manufacture of a card using the mold of Figure 5 is performed as follows: the mold is opened, that is to say, the portions 70 and 74 are spaced from the fixed part 78. A carrier film 12 of printing elements provided with its electronic module 32 is placed between the portions 70 and 78 of the mold as has already been described in connection with Figure 3.

p0033A second film 12 'supporting the printing element, but without the electronic module is placed in the same manner between the parts 78 and 74 of the mold. Then the mold is closed with locking means not shown in Figure 4. As the carrier film 12 and 12 'are integral with the mold as are pinched between the three parts 70, 74 and 78 of the mold. This is followed by the injection of plastic material into the mold through the nozzles 82 and 84, and demoulding the resulting map.

p0034In the above description it has been considered the case where a graphics should also be made on at least one of the main faces of the card body. It is obvious that the first object of the invention is to manufacture a memory card with no graphics. In this case the supporting film has only function is to ensure the positioning and holding the module in the mold. It is therefore devoid of print elements. The carrier film must be made of a material which does not adhere to the injection material at its injection temperature that is to say at a temperature of the order of 200 to 280 ° C. Regarding the adhesive material that serves to fix the electronic module on the carrier film, it must have certain characteristics. It must retain its adhesive properties during the mold filling stage. Preferably it loses, by thermal effect, its adhesive properties during the cooling phase of the molding material. Thus, during the demoulding of the card it is easily separated from the carrier film. Eventually we proceed to chemical cleaning of the external contact pads to remove residual traces of adhesive material.