Abstract:
The invention concerns an electronic data storage medium including a body ( 30 ) made from insulated plastic material which has two main parallel sides, a semiconductor component ( 34 ) and a number of external electrical contact pads flush with the first main side ( 30   a ) of the body. 
     The body ( 30 ) includes a recess ( 32 ) opening out onto the first main side ( 30   a ). 
     The storage medium also includes a number of conducting elements ( 28 ), each with a first end (a) flush with the first main side to form an external contact pad, a second end (b) arranged in the said recess and an intermediate part (c) buried in the body; and 
     A number of connecting elements ( 38 ) to electrically connect the terminals of the semiconductor component to the second ends of the conducting elements.

Description:
FIELD OF THE INVENTION  
       [0001]    This invention concerns an electronic data storage medium of the type with a body of insulating material and a semiconductor component fixed in the said body and a mode of realization of such a storage medium. 
         [0002]    An electronic data storage medium is considered to be a portable object composed of a body generally made from plastic material in which is fixed a semiconductor component formed by electronic circuits which can store data and generally process it. The semiconductor component is connected electrically to external electrical contact pads to make the electrical link between the semiconductor component and the circuits of a reading and writing device into which the storage medium is inserted. 
         [0003]    The reading and writing device is associated with various devices controlled by the reader, these devices may be ticket distributors, payment terminals, fixed telephones or GSM type portable telephones. The term electronic memory cards or bank cards is used for the storage media used in payment terminals or in fixed telephones, these cards having a right parallelepiped body and reduced thickness whose dimensions are defined by standards. For portable telephones, the so-called SIM cards may have various types of body shape adapted to the readers associated with the portable telephones. 
         [0004]    This invention concerns the various types of electronic data storage media defined above. 
       BACKGROUND OF THE INVENTION  
       [0005]    To manufacture these types of electronic data storage media, the technique most often used is as follows: 
         [0006]    in a first step, a data storage medium body is created with the required external shape, and including a recess. In a second step, an electronic module is produced, composed of the semiconductor component which is fixed on a support, this support itself defining the external electrical contact pads connected to the semiconductor component. Lastly, the electronic module is fixed in the recess of the body of the electronic data storage medium. 
         [0007]    These various steps and in particular the realization of the electronic module are relatively complex and therefore generate relatively high costs, whereas the manufacture of the electronic data storage medium must have a global manufacturing cost as low as possible so that this cost has no significant impact on the service that can be obtained using the electronic data storage medium. 
         [0008]    Also, the electronic module is “relatively large” and it is difficult to fix in the recess of the body of the electronic data storage medium. 
       SUMMARY OF THE INVENTION  
       [0009]    The first objective of this invention is to supply an electronic data storage medium which can be manufactured at a lower cost whilst offering the same quality. 
         [0010]    To reach this objective, according to the invention, the electronic data storage medium includes a body made from insulated plastic material which has two main parallel sides, a semiconductor component and a number of external electrical contact pads flush with the first main side of the body. It is characterized in that:
       the said body includes a recess opening out onto the first main side, in which the semiconductor component is fixed,   the said storage medium also includes:
           a number of conducting elements, each conducting element having a first end flush with the first main side to form an external contact pad, a second end arranged in the said recess and an intermediate part buried in the body; and   a number of connecting elements to electrically connect the terminals of the semiconductor component to the second ends of the conducting elements; the volume of the said recess not occupied by the said semiconductor component being filled by an insulating material.   
               
 
         [0015]    We can see that in the electronic data storage medium defined above, the conducting elements intended to form external electrical contact pads and some of the electrical connecting assembly between the semiconductor component and the external contact pads are partly buried in the plastic body of the data storage medium, thereby fastening them and positioning them with respect to the body of the data storage medium, this body including a recess in which the semiconductor component alone can be easily fixed. After fitting the electrical connecting elements, the recess is filled with a plastic material such as an epoxy resin to obtain the final shape of the electronic data storage medium. 
         [0016]    According to a preferred mode of realization, the electrical data storage device is characterized in that each electrical conducting element has the shape of a blanked part, the two ends of this part being approximately parallel and the intermediate part being inclined and having a non rectilinear shape, the recess being offset with respect to the portion of the main side of the body containing the first ends of the electrical conducting elements which form the external electrical contact pads. 
         [0017]    According to this preferred mode of realization, the recess intended to receive the semiconductor component is offset with respect to the location of the external electrical contact pads. It is therefore possible to use a large semiconductor component whilst giving all the external electrical contact pads the configuration which is provided for in particular by the ISO standards concerning bank cards or cards for fixed telephones. 
         [0018]    Another objective of this invention is to supply a mode of realization of an electronic data storage medium which reduces the cost of manufacture whilst producing electronic data storage media which have the same characteristics as with the modes of realization of the prior art. 
         [0019]    To reach this objective according to the invention, the method of manufacturing an electronic data storage medium including a body, a semiconductor component, external electrical contact pads and electrical connecting elements between the said component and the said external contact pads, is characterized in that it includes the following steps:
       a mould is supplied, whose cavity has the shape of the body to be produced, the said cavity having one main side flat, the said mould having a core projecting into the said main side;   in the said cavity a number of electrical conducting elements are arranged, each having a first end applied against the said main side, to form an external contact pad, a second end applied against the said core and an intermediate part;   a hot thermoplastic material is injected under pressure into the said cavity so that the said material fills the entire volume of the cavity not occupied by the said conducting elements;   the part so produced is demoulded, to obtain the body of the data storage medium with a recess, the first ends of the conducting elements being flush with the main side, the second ends of the conducting elements being flush with the wall of the said recess, the intermediate part of the conducting elements being buried in the thermoplastic material;   the said semiconductor component is fixed in the said recess;   the second ends of the conducting elements are connected electrically to the terminals of the semiconductor component; and   the volume of the said recess not occupied by the said semiconductor component is filled with an insulating material.       
 
         [0027]    Other features and advantages of the invention will appear on reading the description which follows of several modes of realization of the invention given as non-limiting examples. The description refers to the attached figures, on which: 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0028]      FIG. 1  is a vertical cross section of an injection mould which can be used to manufacture the data storage medium; 
           [0029]      FIGS. 2   a  to  2   c  are vertical cross sections of the storage device illustrating the various steps of its manufacture; 
           [0030]      FIG. 3  is a partial plan view of a finished data storage medium; 
           [0031]      FIG. 4  is a plan view of a first realization variant of the data storage medium; 
           [0032]      FIG. 5  is a plan view of a second realization variant of the data storage medium; and 
           [0033]      FIG. 6  is a partial vertical cross section of a third realization variant of the data storage medium. 
       
    
    
     DETAILED DESCRIPTION  
       [0034]    Referring firstly to  FIGS. 1 to 3 , we will describe a preferred mode of realization of the electronic data storage medium. 
         [0035]      FIG. 1  shows a vertical cross section of an injection mould which can be used to manufacture the body of the data storage medium. The mould  10  is formed from a lower fixed part  12  and an upper mobile part  14  which define a hollow or cavity. The cavity  16  has the external shape of the body of the data storage device and has two main flat parallel sides  18  and  20  and an outer edge  22  defined by parts  12  and  14  of the mould. The mould also has a injection nozzle  24  for the plastic material used to make the body of the data storage medium. In the main side  20  of the mould cavity  16  a core  26  is mounted, projecting into the main side  20  to form a recess in the body obtained by moulding. 
         [0036]    Before injecting the plastic material through the nozzle  24 , conducting elements such as  26  and  27  are positioned, intended to form the external electrical contact pads of the storage medium and part of the connection between the semiconductor components and the external contact pads. In this mode of realization, the conducting elements  26  and  27  include a first end a, a second end b and an intermediate part c which are obtained for example by folding a metal strip. The ends a and b are parallel whereas the intermediate part c is inclined. The mould  10  includes means not represented to press the ends a of the conducting elements  26  and  28  against the main wall  20  of the cavity  16  and means to press the second ends b against the end side  26   a  of the core  26 . These support means can either be vacuum systems or electromagnetic systems. It must be pointed out that the intermediate parts c of the conducting elements  27  and  28  are kept away from the side wall  26   b  of the core  26 . Means are also provided to maintain the positioning of the conducting elements  27  and  28  in the mould cavity. 
         [0037]    The thermoplastic material is injected into the mould cavity  16  via the injection nozzle(s)  24 . The material is injected hot and under pressure. The injection material can be for example ABS or other similar materials. If ABS is used, the injection temperature lies preferably between 270 and 290° C. whereas the mould and the core are kept at a temperature of preferably between 10 and 50° C. 
         [0038]    After solidification of the moulding material, the part so produced is demoulded. It is represented on  FIG. 2   a . It consists of a moulded part  30  forming the body of the data storage medium which of course has the shape of the mould cavity  16  with the recess  32  formed by the core  26 .The conducting elements  27  and  28  are fastened to the body  30  especially due to the fact that their intermediate parts c are buried in the plastic material. However, the first ends of the conducting elements a are flush with the main side  30   a  of the data storage medium whereas the second ends b are flush with the bottom  32   a  of the recess. 
         [0039]    In the next step represented by  FIG. 2   b , the semiconductor component  34  is fixed on the bottom  32   a  of the recess  32  by any suitable means. The semiconductor component includes terminals  36  in its upper side  34   a . The electrical connection between the terminals  36  of the semiconductor components and the ends b of the conducting elements  27 ,  28  are made with soldered conducting wires such as  38 . 
         [0040]    To carry out this step, the “flip-chip” technique can also be used. This technique consists of making a conducting bump on each terminal of the semiconductor chip. These bumps are fixed directly on the ends b of the conducting elements  28 . This avoids the use of conducting wires. We can see that in this case, the side  34   a  of the semiconductor chip with the terminals  36  is turned towards the bottom  32   a  of the recess  32 . Preferably, a layer of insulating material is first applied on side  34   a  of the chip between the conducting bumps, this layer having approximately the same thickness as the bumps. 
         [0041]    In the last step illustrated by  FIG. 2   c , the volume of the recess  32  not occupied by the semiconductor component  34  is filled with an insulating plastic material  40  which may, for example, be an epoxy resin. The upper side  40   a  of this material may possibly be machined on the surface so that this upper side is flush in the upper side  30   a  of the body of the data storage medium. 
         [0042]      FIG. 3  represents a plan view of part of the body  30  of the data storage medium. This figure shows the ends a of the conducting elements  27  and  28 . Preferably, the conducting elements  27  and  28  are arranged in two parallel rows of four conducting elements. These ends a form the external electrical contact pads  42  and  44  of the data storage medium. This figure also shows the upper side  40   a  of the plastic material filling the recess  32 . 
         [0043]      FIG. 4  represents a plan view of a realization variant of the electronic data storage medium if this storage medium forms a SIM card of modifiable dimensions. The body of the storage medium  50  which is obtained by moulding, as previously explained, has a first portion  52  which contains the semiconductor component  34  and a second portion  54 , these two portions being connected by snap-off areas  56  made from the same plastic material. To provide the mechanical strength of the body of the data storage medium, during the injection moulding, it would be possible to insert metal grids such as  56  and  58  in the mould cavity. The internal sides of the two parts of the mould are preformed to obtain the hollows defining the snap-off areas  56 . 
         [0044]    Preferably, the card body obtained by moulding has the dimensions of an ISO type card, i.e. rectangular shape with dimensions approximately 8.5 mm×55 mm. From the card so obtained, a card with the shape represented on  FIGS. 4 and 5  can be obtained, either by planning, during the moulding, pre blanking slots or by blanking the card body after the moulding step. 
         [0045]    In the mode of realization represented on  FIG. 4 , the external electrical contact pads  42  and  44  are arranged each side of the recess  32  containing the semiconductor component  34 . This arrangement is only suitable if the semiconductor component  34  has relatively reduced dimensions so that connecting elements can be fitted between the terminals of the semiconductor component and the external contact pads represented on  FIG. 2 . This is the configuration which is presently used for bank cards or cards for fixed telephones. 
         [0046]      FIG. 5  represents a realization variant allowing the use of a semiconductor component  60  of larger dimensions. 
         [0047]    According to this mode of realization, the recess  62  made in the body  64  to take the semiconductor component  60  is offset with respect to the area  66  of the body, flush with the external electrical contact pads  68  and  70 . To obtain this offset, the electrical conducting elements  72  and  74  placed in the mould have a special shape. Each conducting element  72  or  74  has a first end a′, a second end b′ and an intermediate part c′. The first and second ends a′ and b′ are identical with the ends a and b of  FIG. 2  or  4 . However, the intermediate part c′ is blanked from a conducting sheet so as to produce a non rectilinear shape (U shape) to obtain the offset between the recess  62  and the external contact pads  68  and  70  formed by the ends a′ of the conducting elements  72  and  74 . We may also consider that the intermediate parts c′ of the conducting elements  72  and  74  are perpendicular to the ends a′ and b′. 
         [0048]    With this arrangement, the spacing e between the two rows of external contact pads  68  and  70  provided for by the standards can be respected whilst creating a space e′ between the second ends b′ of the conducting elements which is compatible with the dimensions of the semiconductor components  60 . 
         [0049]      FIG. 6  shows a third mode of realization of the card body. During the moulding operation, a special shape is planned for the cavity in order to realize a projection  80  of the card body  82  parallel to one edge of the card body. This projection forms a male clipping part, for example, in the shape of a dovetail. The card body  82  can then be fixed on an extension  84  of the card body so that the body of the card so obtained has greater dimensions. The extension  84  includes, for example, a groove  86 , also in the shape of a dovetail, to clip mechanically onto the male part  80 .