Abstract:
A method of manufacture of an electrical bridge including the following steps: (a) providing a first flexible electrically insulating material, (b) laminating a pattern of a second electrically conductive material, on the first material, (c) separating a strap having a connection portion formed from the pattern of electrically conductive material.

Description:
FIELD OF THE INVENTION 
     The instant invention relates to methods of manufacture of IC contact-less communication devices. 
     BACKGROUND OF THE INVENTION 
     Contact-less communication devices have now become fairly common in our everyday life. Such devices notably include contact-less cards, which enable to identify its bearer by a simple swiping movement before a suitable reader, or tags, such as anti-theft tags, to name a few. Such contact-less devices comprise an IC chip, which holds information about the product or the card-bearer, and an antenna, connected to the chip, to transmit this information to the reader. 
     The antenna classically is a coil comprising many turns, and having two ends, which have to be connected to one another to make the antenna operable. So-called “straps” have been used to electrically connect these two ends, without short-circuiting the turns of the antenna located between the ends. An example can be found in WO 2007/068,280. This example is satisfactory in many respects. 
     However, one strives to provide alternative ways to manufacture IC contact-less communication devices. 
     SUMMARY OF THE INVENTION 
     To this aim, it is provided a method according to claim  1 . 
     With these features, a manufacturing method is provided, in which the strap is obtained by lamination, which is a well-known and well-controlled process. Hence, reproducibility of the manufacturing as a whole is improved. 
     In some embodiments, one might also use one or more of the features as defined in the dependent claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other characteristics and advantages of the invention will readily appear from the following description of some of its embodiments, provided as a non-limitative example, and of the accompanying drawings. 
       On the drawings: 
         FIG. 1  is a schematic planar view of a card body according to a first embodiment, 
         FIGS. 2   a  to  2   d  are schematic partial perspective views of manufacturing steps of a strap according to a first embodiment, 
         FIG. 2   e  is a schematic view of the product of  FIG. 2   d  along another perspective, 
         FIG. 2   f  is a schematic partial perspective view of a manufacturing step of a strap according to a second embodiment, 
         FIG. 3   a  is a perspective view of a strap manufactured according to the first embodiment, 
         FIG. 3   b  is a schematic planar view of an IC-card according to a first embodiment, 
         FIG. 3   c  is a partial sectional view of an IC-card along line IIIc-IIIc of  FIG. 3   b,    
         FIG. 4  is a schematic planar view of a card body according to a second embodiment, 
         FIG. 5   a  is a perspective view of a strap manufactured according to the second embodiment, 
         FIGS. 5   b - 5   c  are views similar to  FIGS. 3   b - 3   c , respectively for a second embodiment, 
         FIGS. 6   a  and  6   b  are two perspective views of variant embodiments of the strap of  FIG. 5   a,    
         FIG. 7   a  is a view similar to  FIG. 6   a  for a third embodiment of a strap, 
         FIG. 7   b  is an opposite perspective view of the strap of  FIG. 7   a,    
         FIG. 8  is a perspective view of a third embodiment of an IC-device, and 
         FIG. 9  is a view similar to that of  FIG. 8  of a fourth embodiment of an IC-device. 
     
    
    
     On the different Figures, the same reference signs designate like or similar elements. 
     DETAILED DESCRIPTION 
       FIG. 1  shows a card body  4  used for the manufacture of an IC contact-less communication device according to a first embodiment, here, an IC-card. The card body  4  can be manufactured conventionally, and its manufacture process will not be described in more details here. The card body  4  comprises a generally flexible card substrate  5  which carries or embeds an antenna  1  which can, for example, be shaped to the same size as the substrate. The antenna, performed as a coil having many turns, has two ends  2  and  2 ′ separated by at least one of the turns. These two ends form two opposite connection portions. Further, the antenna  1  comprises two pads  3  and  3 ′ adapted for the connection of an IC chip. For example, as shown, the two pads  3  and  3 ′ are located close to one of the connection portions  2 ′, although other embodiments are possible. 
       FIGS. 2   a  to  2   d  now show steps of the manufacturing of a strap for the card body  4  of  FIG. 1 . The strap is designed to connect together the ends  2  and  2 ′ of the antenna, without short circuiting the intervening turns. As shown on  FIG. 2   a , an elongated band  6  of flexible, electrically insulating material is provided. The band  6  is for example unwound from an unshown unwinding station, and is made to progress along its longitudinal direction X in an apparatus in any conventional way. The direction in which the band is longest is called its longitudinal direction X, and the direction along which it is the shortest is called the thickness direction Z. The width is defined along the third direction Y. The band has two opposite faces  6   a  and  6   b  with respect to the thickness direction Z. On  FIG. 2   a , only a part of the band, which will provide two straps, is shown. The same part is shown until  FIG. 2   d.    
     As shown on  FIG. 2   b , the band  6  progresses to a glue application station of the apparatus, where glue  7  is applied onto one of the main faces  6   a  of the band  6 . Any suitable kind of glue can be applied. 
     As shown on  FIG. 2   c , the band  6  then moves to a perforation station in which through holes  8  are performed in the band  6 , for example following a periodic pattern along direction X and Y. The through holes  8  are performed along the thickness direction Z and extend throughout the band  6  from the first face  6   a  to the second face  6   b . On  FIG. 2   c , which corresponds to two straps, four through holes  8  are performed. Thus, the upper part of  FIG. 2   c  and the lower part of  FIG. 2   c  will each correspond to a strap. Each future strap comprises a through hole  8  corresponding to the one on the left side of  FIG. 2   c  and one corresponding to the one on the right side of  FIG. 2   c.    
     As now shown on  FIG. 2   d , a pattern of an electrically conductive material, such as copper, is laminated on the band  6 , and in particular on a main face  6   a  of the band  6 . The pattern is for example a continuous layer  9  of metal, which is continuous along a part of the band at least corresponding to one future strap, and, as shown, at least corresponding to two future straps. In the present example, where glue  7  is present on the main face  6   a  of the band, a metal foil  9  is glued on this surface. 
     As can be shown on  FIG. 2   d , the electrically conductive foil  9  completely covers the through holes  8  previously performed in the insulative material.  FIG. 2   e  shows a reverse perspective view of a product of  FIG. 2   d.    
     Also shown on  FIG. 2   e , with dotted lines  10 , a strap is separated from the product by cutting, or the like, along the lines  10 . In particular, the separation line  10  passes through the through holes  8 , in this embodiment. 
     The resulting strap can be shown on  FIG. 3   a . It comprises a layer  1  of the electrically isolating material, obtained from the band  6 , and a second layer  12  of electrically conductive i.e. metallic material, obtained from the foil  9 . Due to the location of the separation (the line  10 ) as shown on  FIG. 2   e , the second layer  12  is longer, along direction X, than the first layer  1  on each lateral side, since the separation line  10  passes through the hole  8 . Thus, each lateral side of the second layer  12  defines a connection portion  13 ,  13 ′ in which the second layer  12  extends, but not the first layer  1 . Hence, in each connection portion  13 , the second layer  12  has a first free face  14   a  and an opposite second free face  14   b , opposite to one another with respect to the thickness direction Z. 
     As shown on  FIGS. 3   b  and  3   c , the strap  15  as shown on  FIG. 3   a  is placed onto the card body  4 , with its first connection portion  13  facing the corresponding first connection portion  2  of the antenna  1 , and its second connection portion  13 ′ facing a second connection portion  2 ′ of the antenna  1 . The face  14   b  faces the respective connection portions  2 ,  2 ′ and the strap is assembled thereto, for example by applying heat and/or ultrasonic energy on the first face  14   a  of the connection portions as shown by the arrows on  FIG. 3   c . The strap is oriented with its insulative layer  1  disposed in between the turns of the antenna  1  and the second layer  12  of electrically conductive material along the thickness direction Z, to prevent any short-circuit. In this way, an electrical connection is performed between the connection portion  2  of the card body and that  13  of the strap, as well as between the connection portions  2 ′,  13 ′. In alternative, only one of these connections could be performed as disclosed above, the other connection being possibly performed by any other conventional method, when applicable. 
     Turning back to  FIG. 3   b , an IC chip  16  is mechanically fixed onto the card substrate  5  and is electrically connected between the pads  3  and  3 ′ by any suitable means. The card will be able to communicate with a suitable reader at a frequency in the range of radio frequencies such as, for example, 13.56 MHz. 
     A card body  4  according to a second embodiment is schematically shown on  FIG. 4 . In the following, we will describe the second embodiment with reference to the first embodiment, but not describe again features which are identical or similar to the first embodiment. The card body  4  of the second embodiment differs mainly from that of the first embodiment by the lacking of pads  3 ,  3 ′ for the connection to an IC-chip. The IC-chip is carried by the strap itself. 
     According to the second embodiment, the manufacture of a strap begins as described above in relation to  FIGS. 2   a  to  2   d . As shown on  FIG. 2   f , a pattern of electrically conductive material is formed which is different from the continuous pattern of the first embodiment. This pattern is performed by any suitable technique, such as for example, protecting part of the foil  9  with a suitable mask, and etching the non protected parts, so as to perform one or more grooves  17  in each future strap, where the groove does not contain any electrically conductive material. Two or more conductive portions of the pattern could thus be electrically insulated from one another. A groove  18  can also be performed between two neighbour straps, if desired. The masking material can then be removed, for example by chemical etching. 
     A strap  15  according to a second embodiment is then separated from the band, as shown on  FIG. 5   a . As shown on this figure, separation is not performed along the same line as the first embodiment, i.e. does not pass through the through holes. The part of the first layer  1  which surrounds each hole  8  is a part of the strap. The strap thus comprises a first layer  1  of an electrically insulating material, and a second layer  12  of electrically conducting material, which is not longer (for example of the same length) than the first layer  11  along the X direction, and comprises a first band of metal  19  and a second band of metal  19 ′ which are electrically insulated from one another by the groove  17 , and each cover a respective through hole  8  of the first layer  11 . Thus, the first band of metal  19  comprises, at the level of the through hole, a first free face  14   a  and an opposite second free face  14   b  opposed along the thickness direction Z. The same applies to the second band of metal  19 ′. 
     An IC chip  16  is mechanically fixed to the strap  15 . For example, the chip  16  has two electrical connection portions on its bottom face (with the orientation of  FIG. 5 ) which are brought in electrical communication each with a respective band  19 ,  19 ′, while the chip is anchored on the strap (so called “flip-chip” connection). The chip  16  bridges over the groove  17 , or in any case, the electrical connection portions of the chip are not short-circuited thanks to the groove  17 . In a variant embodiment (not shown), the chip  16  could be mechanically anchored reversed with respect to the above description, and its electrical connections facing up on  FIG. 5   a . The chip is electrically connected to the bands  19 ,  19 ′ by wire bonding, for example golden wire bonding. Encapsulation in resin is then performed. 
     The resulting strap  15  is connected to the card body  4  as shown on  FIGS. 5   b  and  5   c . On  FIG. 5   c , the arrows still show where the welding energy is applied. The connection portions  13  and  13 ′ are defined as parts of the electrically conductive layer  12  of the strap which overlie the holes  8  of the first insulating layer, and in which the connection portions  2  and  2 ′ of the card body  4  are received. 
     According to a third embodiment, it will be understood that the card body  4  of  FIG. 1  could be used with a strap  15 , as shown on  FIG. 5   a , but without the IC chip  16  and the groove  17 , i.e. with a continuous layer of electrically conductive material  12 . 
     In yet another embodiment, the card substrate of  FIG. 4  could receive a strap as shown on  FIG. 3   a , further comprising a groove  17  and an IC chip mounted directly on the strap as explained above with respect to the second embodiment. 
     In other embodiments, it will be understood that lamination is not necessarily performed by gluing, and that it is possible to laminate a metallic layer by cladding, in which case the holes will be performed after cladding in the layer of insulating material, for example by laser or the like. 
     It should be mentioned that, due to the above disclosed method, grooves  17 ,  18  of very small dimensions, for example of less than 100 μm width could be performed. 
     According to a variant embodiment of  FIG. 5   a , which is shown on  FIG. 6   a , the groove  17  could be provided with a stepped shape. Further, recesses  24  could be performed in the bands of metal  19 ,  19 ′, to improve the flexibility of the strap  15 . These recesses  24  are performed outside the connection portions  13 ,  13 ′. The recesses  24  can take any appropriate shape, such as shown on  FIG. 6   a . For example, they are manufactured beforehand by through holes or blind holes in the foil  9  ( FIG. 2   d ). 
     According to yet another embodiment, as shown on  FIG. 6   b , the groove  17  could be performed with an accurate shape. Thus, many kinds of shapes are possible for the groove  17 .  FIG. 7   a  shows yet another embodiment of a strap  15  with a groove  17  with a stepped shape. As shown in particular on  FIG. 7   b , which is the reverse side of  FIG. 7   a , holes  8  enable to define the connection portion  13  and  13 ′ of the strap. 
     According to yet another embodiment, as shown on  FIG. 8 , the strap  15  is not necessarily integrated in an IC chip card. It will for example be welded, on both sides to an antenna  1  which comprises an electrical wire  20  terminating at a connection end  2 ,  2 ′, and an insulating sheath  21 . At its other end, away from the strap, the sheath  21  could be terminated by a rounded protective ball  22 ,  22 ′. As shown on  FIG. 9 , the strap  15  and the ends of the sheath  21 ,  21 ′ close to it could then be encapsulated in a plastic housing  23  for protection. The device of  FIG. 9  could for example be used as an IC tag, for example incorporated in towels or the like, and communicates with a suitable reader, in a range of ultra high frequencies (UHF), for example 860 MHz.