Abstract:
The present invention provides a method for manufacturing IC card by laminating a plurality of foils. The method of the present invention includes steps of putting a COB, a contact electrode of the COB facing downward; laying at least 2 foils having a hole, wherein said COB is inserted in said respective holes of the foils; laying a foil not having a hole on the foils having a hole; and compressing all of the foils.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a method of manufacturing an IC card, and more particularly, to a method of manufacturing a dual-interface IC card in which two or more foils having corresponding holes formed therein are stacked on a chip-on-board (hereinafter, referred to as “COB”) and are then compressed each other. 
     BACKGROUND OF THE INVENTION 
     A card on which data and programs are mounted on a COB, i.e., an IC card has been increasingly used in a variety of fields due to its convenience and the ability to retain information. Such an IC card is mainly classified into a contact type IC card to/from which information is inputted/outputted as a terminal for a card reader and an electrode are brought into contact with each other, a non-contact type IC card to/from which information is inputted/outputted through an antenna even without contacting the terminal for the card reader, and a combi type IC card (also referred to as “dual-interface IC card”) having both the functions of the contact and non-contact type cards. 
     The dual-interface IC card is manufactured by stacking a plurality of foils (also referred to as “sheet”) to form a card shape, digging a groove  900  having a predetermined size by means of a milling process so that a COB  200  can be mounted in the groove  900 , inserting the COB  200  into the groove  900 , and then covering the resulting surface with at least one cover foil, as shown in  FIG. 1 . This method, however, needs a process of digging the groove  900  for the COB  200  in a card base that is roughly formed by stacking the plurality of the foils. Due to this, this method has a disadvantage that the process is dually performed. In particular, in manufacturing the combi type IC card, after the COB is inserted into the groove with an electrode surface for a contact terminal exposed outwardly, an antenna electrodes of the COB and an antenna on which a conductive wire is wound in a given form must be electrically connected. This makes it very difficult for a worker to connect both ends of the antenna and the antenna electrodes of the COB in a state where the worker does not see the both ends of the antenna and the antenna electrodes. 
     In other words, in a state where the ends of the antenna are exposed toward the inside of the groove, the COB is inserted into the groove with a molding element directed downwardly. In this case, the antenna electrodes formed in a main board of the COB must be electrically connected to the both ends of the antenna. At this time, as the COB is located between the eyes of the worker and the groove, i.e., the antenna connection elements, this veils the visual field of the worker (in other words, electrodes to be connected to the antenna are located at the rear of the main board that is not seen by the worker). For this reason, a conductive paste (or adhesive) is covered on both ends of the antenna exposed toward the inside of the groove, and the COB is inserted/then compressed, or a hot melt sheet is adhered and the COB is inserted and then thermally compressed. 
     However, the electrical connection of the antenna connection elements and the COB electrodes becomes unsatisfactory through such adhesion method. In this case, if the IC card is used for a long time, there is a problem that the electrical connection may be disconnected or the COB itself may be separated from the card. Furthermore, in order to insert the COB into the groove formed in the stacked foil, it is inevitable that the area of the groove is greater than the area of the COB in structure even a little. Accordingly, in case of a completed IC card, a gap may exist between the COB and the groove. This gap may cause a possibility that moisture is infiltrated. Further, if the card is bent, the COB may be deviated from the card plate through the gap. 
     OBJECTS OF THE INVENTION 
     Accordingly, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a dual-interface IC card and a method of manufacturing the dual-interface IC card that can obviate the process of digging a groove again after foils are stacked. 
     Another object of the present invention is to provide a dual-interface IC card and a method of manufacturing the dual-interface IC card in which a COB and foils can be strongly coupled. 
     Still another object of the present invention is to provide a dual-interface IC card and a method of manufacturing the dual-interface IC card that can minimize a gap between the COB and the foils. 
     Still another object of the present invention is to provide a dual-interface IC card and a method of manufacturing the dual-interface IC card in which an electrode and antenna electrodes of a COB can be strongly coupled. 
     Still another object of the present invention is to provide a dual-interface IC card and a method of manufacturing the dual-interface IC card in which a half-finished product manufacturing process and a finished product manufacturing process are separated. 
     Still another object of the present invention is to provide a dual-interface IC card and a method of manufacturing the dual-interface IC card having a high smoothness. 
     Still another object of the present invention is to provide a dual-interface IC card and a method of manufacturing the dual-interface IC card, which can solve a problem that a hole into which a COB is inserted is contracted due to thermal compression in the IC card half-finished product manufacturing process. 
     According to a first aspect of the present invention, a method of manufacturing a dual-interface IC card does not include the step of digging a groove for inserting a COB into a foil after the foil is stacked. To this end, the method of manufacturing the dual-interface IC card includes the step of forming a hole for inserting the COB into at least one foil, and then stacking and compressing the COB and the foil. In the concrete, the method of manufacturing the IC card includes the steps of disposing the COB so that an electrode surface for a terminal of a COB is oriented downwardly, stacking two or more foils having a hole of a size into which the COB can be inserted so that the COB is inserted into the hole, stacking a foil having a hole not formed therein on the foils, and then compressing the stacked foils. 
     In a second aspect of the present invention of the method of manufacturing the dual-interface IC card, a process of electrically connecting an antenna formed in a foil to an electrode formed in a COB is facilitated. Accordingly, a physical bonding strength between the antenna and the COB electrode becomes strong and an additional adhesive, etc. can be easily used. This results from the process of electrically connecting the antenna formed in the antenna foil and the antenna electrodes of the COB in a state where the antenna electrodes of the COB is disposed upwardly. In the concrete, the COB is disposed so that an electrode surface for a contact terminal of a COB is disposed downwardly. At least one foil having a hole into which the main board of the COB can be inserted formed therein is first stacked so that the COB is inserted into the hole. Next, an antenna foil in which the antenna is formed and the other hole corresponding to the location of the hole is formed, is stacked so that the other hole is inserted into the molding element of the COB. Both ends of the antenna are then electrically connected to the antenna electrodes of the COB. Thereafter, the other foil is stacked at the opposite side to the side that the electrode surface for the contact terminal of the COB is exposed toward the outside. The stacked foils are then compressed. At this time, the molding element of the COB and the antenna electrodes are exposed upwardly through the hole formed in the antenna foil. 
     In a third aspect of the method of manufacturing the dual-interface IC card, the method is divided into a first step half-finished product process and a second finished product process and is compatible with a common practice of manufacturing the dual-interface IC card. Also, in a final finished product manufacturing process, a conventional production line (that is, a printing equipment, an equipment for stacking and compressing printed foils, etc.) is used intact. To this end, the method of manufacturing the dual-interface IC card includes the first step half-finished product manufacturing process, including the steps of forming a hole through which a molding element and antenna electrodes of a COB are exposed at a predetermined location, inserting the wound antenna foil into the molding element of the COB so that both ends of the antenna are exposed toward the inside of the hole, electrically connecting the both ends of the antenna to the antenna electrodes of the COB, stacking a foil having a hole not formed therein on an opposite side to the side for a terminal of the COB that is outwardly exposed, and compressing the stacked foils; and a second step finished product process, including the steps of stacking at least one foil having a hole into which the main board of the COB can be inserted so that the foil has a thickness substantially same as a thickness of the main board of the COB, and compressing the entire stacked foils. 
     According to a fourth aspect of a method of manufacturing the dual-interface IC card, an antenna and electrodes of a COB have a strong bonding strength. In other words, this method includes the step of adhering an antenna formed in an antenna foil and antenna electrodes of the COB through ultrasonic welding, application of a conductive adhesive or adhesion using a hot melt sheet, in a state where the antenna electrodes of the COB are exposed upwardly. In a conventional method of manufacturing an IC card, the COB itself prevents a worker&#39;s visual field. It is thus difficult to directly connect the antenna and the antenna electrodes of the COB. 
     According to a fifth aspect of a method of manufacturing the dual-interface IC card, a bonding strength between a COB and a foil stacked on the COB is doubled by a hot melt sheet. For this purpose, this method further includes the step of adhering a hot melt sheet in which a hole to expose a molding element and antenna electrodes of the COB are formed on a main board of the COB. By including this step, the bottom of the hot melt sheet is adhered to the main board, and the top of the hot melt sheet is adhered to the foil that is subsequently stacked on the hot melt sheet through thermal compression. 
     According to a sixth aspect of a method of manufacturing the dual-interface IC card, a method of manufacturing the dual-interface IC card having a high smoothness is provided. For this, this method includes the steps of applying a filler between a molding element of a COB and a foil stacked on the molding element, and/or applying a filler to a portion in which an antenna and antenna electrodes of the COB are electrically connected. 
     According to a seventh aspect of a method of manufacturing an dual-interface IC card, there is provided a manufacturing method of preventing problems that a hole formed in an antenna foil can thermally shrink due to first thermal compression in a step half-finished product manufacturing process and a COB of the IC card can be deviated from the card plate through a gap between the COB and the card plate when the card is bent. To this end, this method includes the steps of compressing a lamination foil onto the antenna foil in which the antenna is formed to form a base foil, forming a hole into which the molding element of a COB is inserted in the base foil, inserting the hole of the base foil into the molding element of the COB, electrically connecting the antenna electrodes of the COB and the antenna, and stacking the foil having a hole not formed therein on the base foil and then tack-welding the foil. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further objects and advantages of the invention can be more fully understood from the following detailed description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a cross-sectional view schematically shown to explain a method of manufacturing the dual-interface IC card according to a prior art; 
         FIG. 2(A)  is a perspective view shown to explain a method of manufacturing a dual-interface IC card according to an embodiment of the present invention, and  FIG. 2(B)  is a cross-sectional view of the IC card shown in  FIG. 2(A) ; 
         FIG. 3(A)  is a perspective view shown to explain a method of manufacturing a dual-interface IC card according to another embodiment of the present invention, and  FIG. 3(B)  is a cross-sectional view of the IC card shown in  FIG. 3(A) ; 
         FIG. 4(A)  and  FIG. 4(B)  are plane views each showing a second hole formed in an antenna sheet in the method of manufacturing the dual-interface IC card according to an embodiment of the present invention; 
         FIG. 5(A)  is a traverse section view (taken along lines A-A′ in  FIG. 2(A) ) of a dual-interface IC card on which a plurality of foils are stacked in a first step half-finished product manufacturing process according to an embodiment of the present invention, and  FIG. 5(B)  is a longitudinal section view (taken along lines B-B′ in  FIG. 2(A) ) of the IC card shown in  FIG. 5(A) ; and 
         FIG. 6(A)  is a traverse section view of a dual-interface IC card on which a plurality of foils are stacked in a first step half-finished product manufacturing process according to another embodiment of the present invention, and  FIG. 6(B)  is a longitudinal section view of the IC card shown in  FIG. 6(A) . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention will now be described in detail in connection with preferred embodiments with reference to the accompanying drawings. 
       FIG. 2(A)  is a perspective view shown to explain a method of manufacturing a dual-interface IC card according to an embodiment of the present invention, and  FIG. 2(B)  is a cross-sectional view of the dual-interface IC card shown in  FIG. 2(A) . 
     The dual-interface IC card  100  of the present invention has a plurality of foils stacked thereon. One work plate (not shown) that is substantially flat is first laid on the floor. A COB  200  is then placed on the work plate. It is preferred that the work plate is a metal plate having a predetermined thickness. Though it will be described later, the metal plate has an advantage that it can be easily thermally compressed onto the work plate. The COB  200  is a common COB and has a structure in which a chip of a wafer state is disposed on a main board  210  and a molding element  220  is formed on the chip. The molding element  220  does not necessarily refer to only molding, but may refer to anything that can protect the chip, including potting. In the COB  200  for use in a contact type card among such a COB, the bottom of the main board  210 , i.e., an opposite side in which the molding element  220  is formed becomes an electrode surface  211  for an external terminal. Furthermore, in the COB  200  for use in a combi type card, a pair of antenna electrodes  212  to be connected to an antenna  410  are formed on the main board  210 , and the bottom of the main board  210  becomes the electrode surface  211  for the external terminal in the same manner. When placing the COB  200  on the work plate, the electrode surface  211  for the terminal of the COB  200  is disposed to face the work plate. It is thus possible to see the molding element  220  from the upper direction. Hereinafter, “upper direction” refers to a direction that directs from reference numeral  600  to reference numeral  300  and “lower direction” refers to a direction that directs from reference numeral  300  to reference numeral  600 . Hereinafter, a method of manufacturing the combi type IC card will be first described. 
     A hot melt two-sided sheet  700 , i.e., the bottom of the sheet  700  on both ends of which an adhesive material melt and adhered by heat is formed, is adhered to portions except for the molding element  220  and the antenna electrode  212  of the COB  200 . The top of the sheet  700  is adhered to a core foil  500 , which will be described later on. An oilpaper is preferably formed on the top of the hot melt two-sided sheet  700 . Thus, a worker can adhere the core foil  500  to the hot melt two-sided sheet  700  after stripping off the oilpaper. It is preferred that the hot melt sheet  700  is not greater than the outermost edge portion of the COB  200 , i.e., the main board  210  portion. It is more preferable that the portion adhered to the core foil  500  becomes wide by maximum by making the outermost edge of the hot melt sheet  700  substantially coincident with the outermost edge of the main board  210 . 
     Furthermore, a pair of sheet holes  710  or “           ” shaped grooves are formed in the portion contacting the antenna electrodes  212  of the hot melt sheet  700 , so that antenna connection elements  411  to be described later and the antenna electrodes  212  can be electrically connected through ultrasonic welding, adhesion using a conductive adhesive, soldering, etc. A central hole  720  into which the molding element  220  is inserted (preferably, having substantially the same size as the molding element  220 ), is formed at the central portion of the hot melt sheet  700 .
     If the COB  200  to which one side of the hot melt sheet  700  is adhered is located on the work plate, a front cover foil  300  having a hole (hereinafter, referred to as “first hole”  301 ) of substantially the same size as the main board  210  of the COB  200  is laid on the work plate, while the first hole  301  is being inserted into the main board  210 . At this time, it is preferred that as the first hole  301  and the main board  210 , i.e., the outermost edge portion of the COB  200  are approaching by maximum, the size of the adjacent holes is mated. The front cover foil  300  functions to protect the IC card  100  according to the present invention from moisture, etc. and is preferably made of a transparent coating film. In the above, the process of laying the front cover foil  300  may be omitted, if necessary, which will be described later. 
     If the front cover foil  300  is laid on the work plate, an antenna foil  400  having an antenna  410  formed thereon is stacked on the front cover foil  300  (the process of forming the antenna is known in the art and the shape of the antenna may differ from that shown in the drawing). At this time, a second hole  401  is formed in the antenna foil  400 . The size of the second hole  401  is determined so that the molding element  220  and the antenna electrodes  212  of the COB  200  can be exposed when viewed by the worker from the upper direction. Further, the second hole  401  may have the same shape as the first hole  301 . If the second hole  401  has a different shape from the first hole  301 , it is important to expose the molding element  200  and the antenna electrodes  212 . 
     In the drawing, it is shown that the antenna connection elements  411  are exposed toward the inside of the second hole  401  in the “           ” shape. The present invention, however, is not limited to the above example. It is important that the antenna connection elements  411  are adequately protruded toward the inside of the second hole  401  so that the portion corresponding to the antenna ends substantially corresponds to the antenna electrodes  212 . It is, however, to be noted that the technical construction related to the connection of the antenna connection elements and the antenna electrodes can be easily implemented by those skilled in the art. A stacked thickness of the front cover foil  300  is made equal to a thickness of the main board  210  of the COB  200 . The antenna foil  400  may be stacked after the antenna  410  is formed, or the antenna  410  may be formed after a foil having the antenna  401  not formed therein is stacked. Though not particularly specified in this context, it is construed that the antenna foil  400  includes both the two kinds.
     If the antenna foil  400  is stacked, the oilpaper attached to the top of the hot melt sheet  700  is stripped off (the oilpaper may be stripped off before or after the front cover foil is stacked). The antenna connection elements  411  and the antenna electrodes  212  of the COB  200  are then electrically connected. At this time, the electrical connection may be preferably accomplished using ultrasonic welding, soldering, a conductive adhesive and the like. The end of the antenna  410 , i.e., a the antenna connection elements  411  that do not make contact with the antenna electrodes  212  may be adhered to the top of the top of the hot melt sheet  700 , if appropriate. 
     If the antenna connection elements  411  and the antenna electrodes  212  of the COB  200  are electrically connected, a core foil  500  is stacked thereon. A third hole  501  into which the molding element  220  of the COB  200  can be inserted, is formed in the core foil  500 . It is preferable that the size of the third hole  501  is substantially the same area as the area of the molding element  220 , and a thickness of the core foil  500  and a thickness of the molding element  220  are made same. Thus, if a stacked thickness of the front cover foil  300  and the antenna foil  400  becomes same as a thickness of the main board  210  of the COB  200 , there rarely exists a gap between the COB  200 , the front cover foil  300 , the antenna foil  400  and the core foil  500 . 
     If the core foil  500  is stacked, a backside cover foil  600  is stacked on the core foil  500 . The backside cover foil  600  has substantially the same function as the front cover foil  300 . The backside cover foil  600  is preferably made from a transparent coating film. Generally, objects for indicating a subject of the card, giving publicity, etc. are printed on the surface of the IC card. In case of the IC card of the present invention, objects are printed on the bottom of the antenna foil  400  or the top of the core foil  500 . It is preferred that the printed objects are protected by the cover foils  300  and  600 . 
     If the backside cover foil  600  is stacked, the other work plate (substantially flat metal plate) is laid on the backside cover foil  600 . The two work plates are then compressed. In this case, the work plates are heated at constant temperature, whereby the plurality of the foils are well compressed with one another and the top of the hot melt sheet  700  is well adhered to the core foil  500 . The hot melt sheet  700  serves to minimize the gap between the third hole  501  formed in the core foil  500  and the first and second holes  301  and  401 . 
     It has been described above that the IC card is formed by stacking the front cover foil  300 , the antenna foil  400 , the core foil  500  and the backside cover foil  600 , in case where the IC card of the present invention becomes a combi type card. It is, however, to be understood that the front cover foil  300  or the backside cover foil  600  may be omitted, other foils may be further inserted between the foils, and a variety of foils may be stacked, if necessary. It may be necessary that the foils  300 ,  400 ,  500  and  600  have the property that is adhered with one another when being thermally compressed. It is, however, to be noted that existing foils may be employed, if necessary. 
     A case where the IC card according to the present invention becomes a contact type card will be described. In the contact type card, the COB  200  does not have the antenna electrodes  212  described above. The antenna  410  is thus not formed in the antenna foil  400 . Furthermore, in case of using a hot melt sheet, the sheet holes  710  for the antenna electrodes  212  is not formed. Other processes are substantially the same as those for embodying the method of manufacturing the combi type IC card. In other words, the method of manufacturing the contact type card includes laying the COB  200  on the work plate, laying the front cover foil  300  having the first hole  301  on the COB  200 , and then forming the second hole  401  on the front cover foil  300  but stacking the antenna foil  400  having an antenna not formed thereon. The second hole  401  must have the size into which the molding element  220  can be inserted, preferably substantially the same as the size of the first hole  301 . Next, the core foil  500  having the third hole  501  corresponding to the molding element  220  is stacked. The backside cover foil  600  is then stacked on the core foil  500 . 
     It has been described above that the COB  200  is placed on the work plate, and the front cover foil  300  and the antenna foil  400  are then stacked. However, the COB  200  may be inserted into the holes  301  and  401  after the front cover foil  300  and the antenna foil  400  are stacked while the positions of the first hole  301  and second hole  401  are adequately aligned. In this case, if the antenna foil  400  is stacked on the front cover foil  300 , the COB  200  may be inserted into the holes  301  and  401  after the stacked foils  300  and  400  are turned over. Other processes are substantially the same as those for embodying the method of manufacturing the combi type IC card or the contact type IC card. 
       FIG. 3(A)  is a perspective view shown to explain a method of manufacturing a dual-interface IC card according to another embodiment of the present invention, and  FIG. 3(B)  is a cross-sectional view of the dual-interface IC card shown in  FIG. 3(A) . 
     The method of manufacturing the dual-interface IC card according to  FIG. 3(A)  and  FIG. 3(B)  is a modified process of applying the hot melt sheet  700 . In  FIG. 2 , the bottom of the hot melt sheet  700  is not directly adhered to the COB  200 . However, in  FIG. 3 , after the front cover foil  300  and the antenna foil  400  are stacked on the COB  200 , the bottom of the hot melt sheet  700  is adhered to the top of the COB  200  via the second hole  401  of the antenna foil  400 . In this case, the hot melt sheet  700  still needs the central hole  720  for exposing the molding element  220 , but does not need the sheet holes  710  for exposing the antenna electrodes  212 . In other words, a worker can electrically connect the antenna connection elements  411  and the antenna electrodes  212  of the COB  200  with a sufficient visual field, while stacking the antenna foil  400 . Thus, after such electrical connection, the worker can adhere the hot melt sheet  700  to the antenna foil  400 . Accordingly, it does not matter if the hot melt sheet  700  is greater than the second hole  401 . An adhesive strength with the core sheet  500  can be increased by using the hot melt sheet  700  having an area wider than that of the second hole  401 . 
       FIG. 4(A)  and  FIG. 4(B)  are plane views each showing the second hole formed in the antenna sheet according to an embodiment of the present invention. 
     The second hole  401  is formed in the antenna foil  400  of the combi type IC card according to the present invention. It is necessary that the second hole  401  be formed so that the connection elements  411  of the antenna  410  and the antenna electrodes  212  of the COB  200  are seen within the visual field of the worker, i.e., from the upper direction. Accordingly, the second hole  401  includes a central portion  402  having the size greater than the area of the molding element  220  of the COB  200  so that the molding element  220  can be exposed from the upper direction (for reference, the inner side of a closed curve is the hole and the outer side thereof is the antenna foil in FIG.  4 (A)), as shown in  FIG. 4(A) . 
     Furthermore, outer protrusions  403  of an ear shape that are outwardly protruded are formed at both sides of the central portion  402  so that the antenna electrodes  212  can be exposed from the upper direction. The connection elements  411  of the antenna  410  are formed to traverse the outer protrusions  403 . Therefore, the worker can electrically connect the antenna connection elements  411  and the antenna electrodes  212  located below it through the holes of the outer protrusions  403 . For reference, one side of both sides of the antenna foil  400  in which the antenna  410  is formed is oriented downwardly. In other words, the side in which the antenna  410  is formed becomes the side stacked on the front cover foil  300 . It is preferable that the center points of the outer protrusions  403 , the hot melt sheet holes  710  and the antenna electrodes  212  are coincident with one another on the plane. 
     If the hot melt sheet  700  is applied after the antenna foil  400  is stacked, it is preferred that the second hole  401  formed in the antenna foil  400  has a shape as shown in  FIG. 4(B)  (for reference, the inner side of a closed curve is the hole and an outer side thereof is the antenna foil in  FIG. 4(B) ). At this time, the central hole  402  having the size greater than the area of the molding element  220  of the COB  200  is formed in the second hole  401  so that the molding element  220  can be seen from the upper direction, i.e., by the worker&#39;s visual field. Further, a pair of inner protrusions  404  are protruded toward the inside of both sides of the central hole  402 , and the up and down directions of both sides of the central hole  402  with them spaced apart by some distance, respectively. In other words, the four inner protrusions  404  are a portion of the antenna foil  400 . In the connection elements  411  of the antenna  410 , the distance between the pair of the inner protrusions  404  serves as a lateral holes  405  formed at the edge of the central hole  402 . 
     Further, the connection elements  411  of the antenna  410  are formed to traverse the lateral holes  405 . In other words, after stacking the antenna foil  400  in which only the pair of the lateral holes  405  are formed, the worker can electrically connect the antenna connection elements  411  and the antenna electrodes  212  of the COB  200  through the lateral holes  405  and then form the second hole  401  of a shape as shown in  FIG. 4(B)  in the antenna foil  400  by using a puncher, etc. Next, the hot melt sheet  700  is adhered on the second hole  401 , wherein the molding element  220  is outwardly exposed and the hot melt sheet  700  having the size greater than the second hole  401  is employed. 
       FIG. 5(A)  is a traverse section view (taken along lines A-A′ in  FIG. 2(A) ) of the dual-interface IC card on which a plurality of foils are stacked in a first step half-finished product manufacturing process according to an embodiment of the present invention, and  FIG. 5(B)  is a longitudinal section view (taken along lines B-B′ in  FIG. 2(A) ) of the IC card shown in  FIG. 5(A) . In this embodiment, the method of manufacturing the dual-interface IC card is composed of a first step half-finished product manufacturing process and a second step finished product manufacturing process. The first step process includes a process of manufacturing a basic IC card (i.e., the step of inserting the antenna foil and the core foil into the COB and then stacking them), and the second step process includes a process of stacking the printing foils, the coating foil and the like. 
     In the method of manufacturing the dual-interface IC card according to the present invention, the first step process being the half-finished product manufacturing process includes stacking a plurality of foils. A first work plate (not shown), which is generally flat and has a hole formed at its given place that has substantially the same shape and area as the main board  210  of the COB  200 , is first laid on the floor (it is preferred that the first work plate has substantially the same thickness as the main board). The COB  200  whose electrode surface  211  is inserted downwardly is then located in the hole. It is preferable that the work plate is a metal plate of a predetermined thickness. This metal plate has an advantage that it can be easily compressed by heat as it is described later on. At this time, after a plurality of foils for the half-finished product to be described later are stacked, the COB  200  may be inserted into the work plate and then compressed without the need for the process of inserting the COB  200  into the work plate having the hole formed therein. 
     The bottom of the hot melt two-sided sheet  700  is adhered to portions except for the molding element  220  and the antenna electrodes  212  of the COB  200 , and the top of the hot melt two-sided sheet  700  is adhered to the antenna foil  400  to be described later on. As an oilpaper is preferably formed on the top of the hot melt two-sided sheet  700 , the bottom of the hot melt two-sided sheet  700  is adhered to the top of the COB  200  (adhesion by heat) and the oilpaper is then removed. 
     Therefore, the top of the hot melt two-sided sheet  700  can be adhered (adhered by heat) to the antenna foil  400 . It is preferable that the hot melt sheet  700  does not protrude outwardly beyond the outermost edge portion of the COB  200 , i.e., the main board  210  portion. It is more preferable that the portion adhered to the core foil  500  becomes widen by maximum by allowing the outermost edge of the hot melt sheet  700  to be substantially coincident with the outermost edge of the main board  210 . 
     Furthermore, sheet holes  710  are formed or “           ” shape grooves are formed in the portion where the hot melt sheet  700  makes contact with the antenna electrodes  212 . Thus, the antenna connection elements  411  to be described later and the antenna electrodes  212  can be electrically connected through ultrasonic welding, adhesion using a conductive adhesive, soldering and the like. Further, a central hole  720  of substantially the same size as the area of the molding element  220  is formed in the central portion of the hot melt sheet  700 . The molding element  220  of the COB  200  can be thus inserted into the central hole  720 .
     In the COB  200  having the hot melt sheet  700  adhered on its top, the antenna foil  400  in which the second hole  401  is formed at its predetermined location and the antenna  410  is formed at its one side, is laid on the work plate so that the molding element  220  and the antenna electrodes  212  of the COB  200  is exposed when viewed from the upper direction. In the above, the molding element  220  is inserted into the second hole  401 . It may be preferred that the bottom of the antenna foil  400  keeps parallel with the bottom of the main board. As described later, however, it is possible to lay the other at least one foil (for example, a second overlay foil, etc.) before the antenna foil  400  is laid and then to stack the antenna foil  400  on the other at least one foil. 
     Furthermore, the step of applying the hot melt sheet  700  may be changed. In this case, the bottom of the hot melt sheet  700  is not directly adhered to the COB  200 , but may be adhered to the top of the COB  200  through the second hole  401  of the antenna foil  400  after the second overlay foil  20  and the antenna foil  400  are stacked on the COB  200 . In this case, the hot melt sheet  700  still needs the central hole  720  (see  FIG. 2(A) ) for exposing the molding element  220 , but does not need the sheet holes  710  for exposing the antenna electrodes  212 . In other words, a worker can electrically connect the antenna connection elements  411  and the antenna electrodes  212  of the COB  200  with a sufficient visual field, while stacking the antenna foil  400 . Thus, after such electrical connection, the worker can adhere the hot melt sheet  700  to the antenna foil  400 . Accordingly, it does not matter if the hot melt sheet  700  is greater than the second hole  401 . An adhesive strength with the core sheet  500  can be increased by using the hot melt sheet  700  having an area wider than that of the second hole  401 . In case where the hot melt sheet  700  is adhered after the antenna foil  400  is stacked as such, it is preferable that the second hole  401  has a shape shown in  FIG. 4(B) . 
     In the above, the second hole  401  may have a variety shapes. The molding element  220  and the antenna electrodes  212  may be exposed upwardly. Furthermore, it is required that both ends (the antenna connection elements  411  of the antenna  410  be adequately protruded toward the inside of the second hole. The antenna connection elements  411  have to be formed at a location corresponding to the antenna electrodes  212 . Since technology for forming such an antenna connection elements  411  is known to those skilled in the art, detailed description on it will be omitted. In addition, the antenna foil  400  may be stacked after the antenna  410  is formed, or the antenna  410  may be formed after a foil having the antenna  401  not formed therein is stacked. 
     It is preferred that the antenna foil  400  is stacked after the second overlay foil  20  having a hole (hereinafter, referred to as “fifth hole”  11 ) of substantially the same area and shape as the main board  210  of the COB  200  is inserted into the molding element  220  of the COB  200 , before the antenna foil  400  is stacked. In this case, given portions of the second overlay foil  20  and the antenna foil  400  are spot-adhered using ultrasonic waves, i.e., several points of them are tack-welded. By stacking the second overlay foil  20 , it is possible to prevent the antenna  410  from being faintly seen from the outside in the finished IC card. Also, a difference in a thickness that is caused by the hot melt sheet  700  can be thus solved. By making the thickness of the antenna foil  400  sufficiently thick, i.e., by making the thickness of the antenna foil  400  substantially same as that of the molding element  220  of the COB  200 , it is possible to make the thickness of the molding element  220  consisting of only the thickness of the second overlay foil  20  and the antenna foil  400 . It is, however, preferable that the thickness of the antenna foil  400  is smaller than that of the molding element  220  and the step of stacking the core foil  500  is further included. 
     If the antenna connection elements  411  of the antenna foil  400  and the antenna electrodes  212  of the COB  200  are electrically connected, at least one core foil  500  having a third hole  501  of substantially the same shape and area as the molding element  220  is stacked. The third hole  501  is inserted into the molding element  220  of the COB  200 . More preferably, before the core foil  500  is stacked (or while the plurality of the core foils are stacked, i.e., after one of two core foils is stacked), another hot melt sheet (not shown) enough to completely cover the molding element  220  of the COB  200  is adhered. This makes it possible to prevent a gap from generating between the molding element  220  and the antenna foil  400  or the core foil  500  in subsequent thermal compression. In particular, when a hot melt sheet is adhered between the antenna foil  400  and the core foil  500 , the hot melt sheet is adapted to cover up to the second hole  401 . This causes the hot melt sheet to melt, which fills the space around the antenna connection elements  411  in the second hole  401  in subsequent thermal compression. 
     If the core foil  500  is stacked, a first overlay foil  10  having any hole not formed therein is stacked. It is preferred that the first and second overlay foils  10  and  20  are relatively thinner in thickness than the antenna foil  400  and the core foil  500 . It is more preferable that the height of the top of the core foil  500  is higher a little than the height of the molding element  220  of the COB  200  after the at least one core foil  500  is stacked. Furthermore, the upper portion of the molding element  220  corresponding to the difference between the heights of the core foil  500  and the molding element  220  is filled with a filler  800 ′. This makes the thickness of the foils thinner than the molding element  220  in subsequent thermal compression. 
     In other words, during the thermal compression, the thickness of the foils is reduced, while the thickness of the molding element  220  keeps same as before. It thus prevents the thickness of the foil layer from becoming thinner than that of the molding element  220  of the COB  200 . The filler  800 ′ may include an ultraviolet filler that is hardened by ultraviolet rays, an instant adhesive, an adhesive of an epoxy series that is hardened by heat, and so on. At this time, in case of the ultraviolet filler, it is hardened by ultraviolet rays after a transparent plate is placed on a portion to which the filler  800 ′ is supplied. In case of the adhesive of an epoxy series, it is hardened by an additional heating means. 
     If the first overlay foil  10  is stacked, a second work plate that is substantially flat is laid on the first overlay foil  10  (when the first work plate is not initially laid, after the main board  210  of the COB  200  is inserted into the hole the first work plate). At least one work plate is then compressed while applying heat. 
     In the method of manufacturing the IC card according to the present invention, the second step process for manufacturing the IC card finished product is as follows. 
     With respect to the IC card half-finished product formed through the above-mentioned first step process, at least one foil having a hole (not shown) of substantially the same area as the main board of the COB is stacked below the second overlay foil  20 . In the above, the thickness of the at least one foil must be not smaller than that of the main board of the COB (this is because the thickness of the foil portion may be reduced due to thermal compression). At this time, the at least one foil may be a printing foil, if necessary, or a coating foil for preventing abrasion. This corresponds to the front cover foil  300  shown in  FIG. 2(A) . Preferably, the step of stacking the other at least one foil (corresponding to the backside cover foil  600  in  FIG. 2(A) ) that will be coated on the first overlay foil  10 , may be further included. Finally, the entire stacked foils are compressed while applying heat. The method of manufacturing the dual-interface IC card according to the present invention provides a method of manufacturing a dual-interface IC card having a high smoothness by means of twice thermal compressions; thermal compression in the half-finished product manufacturing process and thermal compression in the finished product manufacturing process. 
       FIG. 6(A)  is a traverse section view of a dual-interface IC card on which a plurality of foils are stacked in a first step half-finished product manufacturing process according to another embodiment of the present invention, and  FIG. 6(B)  is a longitudinal section view of the dual-interface IC card shown in  FIG. 6(A) . 
     In the method of manufacturing the dual-interface IC card according to the present invention, the first step process being the half-finished product manufacturing process also basically includes stacking a plurality of foils around a COB. However, before the plurality of the foils are stacked, the step of thermally compressing the antenna foil  400  and a lamination foil  400 ′ to form a base foil  400 ″ is first performed. The antenna foil  400  and the lamination foil  400 ′ are first thermally expanded by thermally compressing them. A fourth hole  401 ″ into which the molding element  220  of the COB  200  is inserted, i.e., through which the molding element  220  is exposed upwardly, is then formed. It is preferred that the antenna hole  402  for exposing the antenna connection elements  411  corresponding to both ends of the antenna  410  is formed in the antenna foil  400  and the lamination foil  400 ′, before the antenna foil  400  and the lamination foil  400 ′ are thermally compressed. 
     A worker can electrically connect the antenna connection elements  411  and the antenna electrodes  212  of the COB  200  through the antenna hole  402 , by using soldering, ultrasonic welding, a conductive paste and the like. At this time, the antenna holes  402  have to be formed in two corresponding to a point where the antenna electrodes  212  of the COB  200  will be located. Those skilled in the art will appreciate that this can be easily implemented. After the antenna hole  402  is formed in each of the antenna foil  400  and the lamination foil  400 ′, the antenna  410  of a predetermined shape is adequately wound on one side of the antenna foil  400 . At this time, it is required that the antenna  410  traverses the antenna hole  402  and both ends of the antenna  410  traverse the antenna hole  402 . 
     If the antenna  410  is formed, the lamination foil  400 ′ is thermally compressed onto the antenna foil  400 . It is preferred that the lamination foil  400 ′ and the antenna foil  400  are thermally compressed so that the lamination foil  400 ′ can cover the side in which the antenna  410  of the antenna foil  400  is formed. The two foil layers formed by such thermal compression become the base foil  400 ″. 
     A fourth hole  401 ″ into which the molding element  220  of the COB  200  is inserted, is formed in the base foil  400 ″ that is formed by thermally compressing the antenna foil  400  and the lamination foil  400 ′. In this case, the fourth hole  401 ″ must have an area through the molding element  220  of the COB  200  can be completely exposed when viewed from the upper direction. It is preferred that the fourth hole  401 ″ has substantially the same shape and area as the molding element  220 . This process of forming the fourth hole  401 ″ may be performed by means of an automation process using a predetermined punching machine. 
     The process of forming the base foil  400 ″ according to an embodiment of the present invention includes forming the antenna hole  402  and the second hole  401  in the antenna foil  400  and the lamination foil  400 ′, respectively, winding the antenna  410  around the antenna foil  400 , and then thermally compressing the antenna foil  400  and the lamination foil  400 ′. At this time, the antenna hole  402  and the second hole  401  have the same shape as that described above, and are suitable for a case where the degree that the foil is expanded is small or uniform even if the antenna hole  402  and the second hole  401  are thermally compressed. 
     The base foil  400 ″ in which the fourth hole  401 ″ is formed is inserted into the molding element  220  of the COB  200  through the fourth hole  401 ″. The antenna connection elements  411  that traverses the base foil  400 ″ and the molding element  220  via the antenna hole  402 , and the antenna electrodes of the COB  200  are then electrically connected. A worker can secure a visual field through the antenna hole  402  and accordingly can obtain a strong physical connection such as soldering, ultrasonic welding and the like. At this time, a conductive paste may be used, if necessary, and all the methods for electrical connection may be used unless specially described. 
     Preferably, before the base foil  400 ″ is inserted into the molding element  220  of the COB  200 , the hot melt two-sided sheet  700 , i.e., the bottom of a sheet where an adhesive material melt by heat is formed at its both sides is adhered (adhered by applying heat using additional device (device having a heater and a pressing plate)) to portions except for the molding element  220  and the antenna electrodes  212  of the COB  200 . Hereinafter (that is, during thermal compression in the second step finished product manufacturing process), the top of the sheet is adhered to the base foil  400 ″, which will be described later. In this case, the top of the hot melt sheet  700  and the base foil  400 ″ may be adhered in advance using the additional device. 
     An oilpaper is preferably formed on the top of the hot melt two-sided sheet  700 . At this time, the bottom of the hot melt two-sided sheet  700  is adhered (adhered by heat) to the top of the COB  200  and the oilpaper is then removed. Therefore, the top of the hot melt two-sided sheet  700  can be adhered (adhered by heat) to the base foil  400 ″. It is preferable that the hot melt sheet  700  does not protrude outwardly beyond the outermost edge portion of the COB  200 , i.e., the main board  210  portion. It is more preferable that the portion adhered to the core foil  500  becomes wide by maximum by allowing the outermost edge of the hot melt sheet  700  to be substantially coincident with the outermost edge of the main board  210 . 
     Furthermore, sheet holes  710  are formed or “           ” shape grooves are formed in the portion where the hot melt sheet  700  makes contact with the antenna electrodes  212 . Thus, the antenna connection elements  411  and the antenna electrodes  212  can be electrically connected through ultrasonic welding, adhesion using a conductive adhesive, soldering and the like. Further, a central hole of substantially the same size as the area of the molding element  220  is formed at the central portion of the hot melt sheet  700 , whereby the molding element  220  can be inserted into the central hole. Or, a hole smaller than the area of the molding element  220  is formed at the central portion of the hot melt sheet  700 , whereby a worker can strip off the oilpaper on the hot melt sheet  700  through the hole.
     It is preferable that the bottom of the base foil  400  keeps parallel with the bottom of the main board. As described above, however, after the other at least one foil (for example, the second overlay foil  20  shown, etc.) is laid before the base foil  400 ″ is laid, the base foil  400 ″ may be stacked on the foil. At this time, it is possible to change the step of applying the hot melt sheet  700 . In this case, the bottom of the hot melt sheet  700  is not directly adhered to the COB  200  unlike  FIG. 2 , but is adhered to the top of the COB  200  through the fourth hole  401 ″ of the base foil  400 ″ after the second overlay foil  20  and the antenna foil  400  are stacked on the COB  200 . 
     In the above, the hot melt sheet  700  still requires a central hole  720  for exposing the molding element  220 , but does not require sheet holes  710  for exposing the antenna electrodes  212 . In other words, a worker can electrically connect the antenna connection elements  411  and the antenna electrodes  212  of the COB  200  with a sufficient visual field, while stacking the base foil  400 ″. The worker can thus adhere the hot melt sheet  700  on it after such electrical connection. Accordingly, it does not matter if the hot melt sheet  700  is greater than the second hole  401 . As the hot melt sheet  700  of the area wider than that of the second hole  401  is used, an adhesive strength with a core sheet  500  to be described later on can be increased. 
     If the antenna connection elements  411  of the base foil  400 ″ and the antenna electrodes  212  of the COB  200  are connected, a filler  800  is supplied to the second hole  401  formed in the base foil  400 ″ and the central hole  720  formed in the hot melt sheet  700 . The IC card completed through the filler thus maintains a generally high smoothness. It is preferred that the adhesive property between the foils is improved by applying the filler  800  having the adhesive property. Such a filler  800  may include an ultraviolet filler that is hardened by ultraviolet rays, an instant adhesive, an adhesive of an epoxy series that is hardened by heat, and so on. At this time, in case of the ultraviolet filler, it is hardened by ultraviolet rays after a transparent plate is placed on a portion to which the filler  800 ′ is supplied. In case of the adhesive of an epoxy series, it is hardened by an additional heating means. 
     As described above, it is preferred that the base foil  400 ″ is stacked after the second overlay foil  20  having the first hole  301  of substantially the same area and shape as the main board  210  of the COB  200  is inserted into the molding element  220  of the COB  200 . At this time, given portions of the second overlay foil  20  and the base foil  400 ″ are spot-adhered, i.e., track-welded by means of ultrasonic waves. Stacking the second overlay foil  20  prevents the antenna  410  from being faintly viewed from the outside in the completed IC card. Further, it can solve a difference in the thickness occurring due to the hot melt sheet  700 , as shown in the drawings. 
     If the filler  800  is applied and hardened, at least one core foil  500  (only one is shown in this drawing) having a third hole  501  of substantially the same shape and area as the molding element  220  is stacked. The third hole  501  is inserted into the molding element  220  of the COB  200 . More preferably, before the core foil  500  is stacked (or while the plurality of the core foils are stacked, after one of two core foils is stacked), the other hot melt sheet (not shown) is adhered enough to completely cover the molding element  220  of the COB  200 . It prevents a gap from occurring between the molding element  220  and the base foil  400 ″ or the core foil  500  in subsequent thermal compression. In particular, if a hot melt sheet is adhered between the base foil  400 ″ and the core foil  500 , the hot melt sheet can cover the fourth hole  401 ″. Thereby, in subsequent thermal compression, the hot melt sheet is melt to fill the space around the antenna connection elements  411  in the fourth hole  401 ″. 
     The antenna foil  400  and the lamination foil  400 ′ may be formed sufficiently thick as much thickness as the core foil  500  without stacking such a core foil  500 . In other words, assuming that a thickness of the molding element  220  is about 0.42 mm, a thickness of the antenna foil  400  and a thickness of the lamination foil  400 ′ may be set to about 0.11 mm and 0.11 mm (or may be different), respectively, and the core foil  500  of 0.22 mm may be then stacked on it, or a thickness of the antenna foil  400  and a thickness of the lamination foil  400 ′ may be set to 0.22 mm and 0.22 mm and the core foil  500  may be omitted. 
     If the core foil  500  is stacked, the first overlay foil  10  having a hole not formed therein is stacked. It is preferable that the first and second overlay foils  10  and  20  are relatively thinner in thickness than the base foil  400 ″ and the core foil  500 . After the at least one core foil  500  is stacked, it is not required that the height of the top of the core foil  500  be necessarily the same as the height of the molding element  220 . 
     In other words, in case where the filler  800 ′ is filled into the upper portion of the molding element  220  corresponding to a difference between the heights of the core foil  500  and the molding element  220  and is thermally compressed later, the thickness of the foils is not made thinner than the molding element  220  since the height of the top of the core foil  500  is slightly higher than the height of the molding element  220  of the COB  200 . In other words, once being thermally compressed, the thickness of the foils is reduced, while the thickness of the molding element  220  is same as before. It prevents the thickness of the foil layer from becoming thinner than that of the molding element  220  of the COB  200 . 
     Furthermore, referring to the expanded drawing (indicated by dotted lines in  FIG. 6(A) ) with respect to the filler  800 ′ applied between the core foil  500  and the molding element  220 , the edge of the molding element  220  does not have an exact rectangular edge shape but a smoothly curved shape. Thus, the smoothness of the final IC card can be further improved by filling the gap between the molding element  220  and the core foil  500  with the filler  800 ′. The filler  800 ′ may be the same as the filler  800 . Of course, the top of the core foil  500  may be formed lower than the molding element  220  of the COB  200 . 
     In the method for manufacturing the dual-interface IC card, the second step process of manufacturing the dual-interface IC card finished product is as follows. 
     In the dual-interface IC card half-finished product that is formed by the first step process, at least one foil (corresponding to the front cover foil  300  in  FIG. 2(A) ) having a hole (not shown) of substantially the same area as the main board  210  of the COB  200  is stacked below the second overlay foil  20 . At this time, the area of the at least one foil is not smaller than the thickness of the main board of the COB (this is because the thickness of the foil portion can be reduced due to thermal compression). At this time, the at least one foil may include a printing foil, if necessary, and a coating foil for preventing abrasion. It is preferred that the step of stacking the other at least one foil (corresponding to the backside cover foil  600  in  FIG. 2(A) ) that will be coated on the first overlay foil  10  may be further included. Finally, the stacked entire foils are compressed while applying heat. 
     As described above, the present invention provides a method of solving a problem that may happen as an antenna foil is contracted due to first thermal compression, while manufacturing an IC card of a higher smoothness through twice thermal compressions; thermal compression in a half-finished product manufacturing process and thermal compression in a finished product manufacturing process. 
     While the present invention has been described with reference to the particular illustrative embodiments, it is not to be restricted by the embodiments but only by the appended claims. It is to be appreciated that those skilled in the art can change or modify the embodiments without departing from the scope and spirit of the present invention.