IC CARD AND FLAT COIL FOR IC CARD

Abstract: Thickness of an IC card is decreased, and the manufacturing efficiency of the IC card is enhanced so as to reduce the manufacturing cost. The IC card comprises: a semiconductor element 14 having electrodes; a plane coil 12 formed in such a manner that a conductor 12b is wound on the same face, having terminals 12a at respective ends; bonding wires 16 for electrically connecting terminals at both ends of the plane coil to the electrodes of the semiconductor element; and resin films 10 for sealing the semiconductor element, plane coil and bonding wires 16 when they are interposed between the resin films, wherein the thickness of the semiconductor element 14 is smaller than the thickness of the plane coil 12, the semiconductor element is arranged in a plane region which is in a range of the thickness of the plane coil 12 and does not interfere with the conductor of the plane coil, and a thin wall thickness portion 12c is formed on a front face of the conductor of the plane coil through which the bonding wires can pass without protruding from the region of the thickness of the plane coil.

Description: FIELD OF THE INVENTION The present invention relates to an IC card, more particularly to a non-contact type IC card, and a plane coil used for such an IC card. The non-contact type IC card includes: a plane coil in which a conductor is wound around a sheet-shaped card material a plurality of times; and a semiconductor electrically connected to the plane coil. The plane coil functions as an antenna by which information can be transmitted between a card processor and the IC card. When the plane coil is disposed between the card processor and the IC card, it is possible to transmit information between the card processor and a semiconductor element provided on the IC card in the non-contact condition. DESCRIPTION OF THE BACKGROUND ART Concerning the method of manufacturing a plane coil to be formed on an IC card, various methods are known. Examples of these methods are: a method in which a plane coil is formed in such a manner that a covered wire, which is covered with electrically insulating material, is wound so as to form the plane coil; a method in which a surface of a resin film is covered with a layer of metallic foil by means of sputtering, and then the layer of metallic foil is etched so as to form a plane coil; and a method in which a metallic sheet is subjected to punching so as to form a plane coil as disclosed in Japanese Unexamined Patent Publication No. 6-310324. Fig. 11 is a view showing an example of the arrangement of an IC card in which the semiconductor element 102 is mounted on the plane coil 100. As shown in the drawing, the plane coil 100 is composed in such a manner that the conductor is wound on a face so that it cannot cross itself and the terminals 100a, 100b of the plane coil 100 are electrically connected with the electrodes of the semiconductor element 102. Concerning the method of connecting the semiconductor element 102 with the plane coil 100, the following methods can be provided. One of the methods is that the conductor of the plane coil 100 is put on the semiconductor element 102 as shown in Fig. 11 and the terminals 100a, 100b of the plane coil 100 are connected to the electrodes of the semiconductor element. The other method is that the terminals 100a, 100b of the plane coil 100 are drawn out to the inside or the outside of the plane coil, and the semiconductor element 102 is connected to the ends of the terminals 100a, 100b which have been drawn out. However, as shown in Fig. 11, when the semiconductor element 102 is arranged in such a manner that it is put on the plane coil 100, the thickness of the IC card is increased to a value corresponding to a total of the thickness of the plane coil 100 and the thickness of the semiconductor element 102. Since the thickness is increased as described above, problems may be caused in the case where the thickness of the IC card must be restricted. Further, in order to connect the terminals 100a, 100b of the plane coil 100 to the electrodes of the semiconductor element 102 as they are, a distance between the electrodes of the semiconductor element 102 must be larger than the arrangement width of the plane coil 100. Accordingly, in the case of a semiconductor element 102, the size of which is smaller than the arrangement width of the plane coil 100, it is impossible to adopt such an arrangement as shown in Fig. 11. In this connection, in some cases, a chip module is used instead of the semiconductor element 102, and the terminals 100a, 100b of the plane coil 100 are connected to the electrodes of the chip module. In this case, the same problem may occur. On the other hand, in the case where the terminals 100a, 100b of the plane coil 100 are arranged inside or outside of the plane coil 100, it is necessary to bend end portions of the plane coil so that they can cross the plane coil 100. Accordingly, the manufacturing process of the plane coil 100 would be complicated. WO96/07982A is specifically directed towards ensuring that the ends of the coil do not cross the coil winding and identifies a problem that occurs when such crossing is present in that the coil thickness is substantially increased. JP-A-1101105 discloses an antenna card wherein the semiconductor element is positioned between adjacent windings of the antenna coil. The terminal ends of the antenna coil cross the coil windings and correspondingly increase the overall height of the card. SUMMARY OF THE INVENTION The present invention has been achieved in order to solve the above problems. It is an object of the present invention to provide an IC card wherein: a semiconductor element of any size can be easily mounted on the IC card; the thickness of the IC card can be appropriately reduced; and the IC card can be easily manufactured. It is another object of the present invention to provide a plane coil appropriately applied to the above IC card. According to the invention there is provided a plane coil as defined by claim 1. Preferred embodiments are defined by the dependent claims. The claims are delimited against WO96/07982A. The conductor of the plane coil may be formed by punching or etching a metallic sheet, and the thin wall thickness portion is formed in a predetermined portion of the conductor. The connecting means may be composed of bonding wires, where bonding connection is made by connecting end portions of the bonding wires between the terminals of the plane coil and the electrodes of the semiconductor element. An outer circumferential surface of the bonding wire may be covered with an electrically insulating covering material. The connecting means may be alternatively a film carrier in which an electrical conductive pattern which is formed on an insulating film, where the electrical conductive pattern is electrically connected with the terminals of the plane coil and the electrodes of the semiconductor element. The semiconductor element may be arranged between adjacent windings of the plane coil. The semiconductor element may be arranged either outside an outer winding of the plane coil or inside an inner winding of the plane coil. A surface of the thin wall thickness portion may be covered with an insulating layer having an electrically insulating property. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an arrangement view of the first embodiment of the IC card of the present invention. Fig. 2 is a plan view showing an arrangement of the connecting section between the semiconductor element and the plane coil. Fig. 3 is a side view showing an arrangement of the connecting section between the semiconductor element and the plane coil. Figs. 4(a) and 4(b) are cross-sectional views showing a state in which an insulating layer is provided on a surface of the thin wall thickness portion provided in the conductor. Fig. 5 is a plan view showing an arrangement of the connecting section in the second embodiment of the IC card. Fig. 6 is a plan view showing an arrangement of the connecting section in the third embodiment of the IC card. Figs. 7(a) and 7(b) are plan and side views showing an arrangement of the connecting section composed of a tape carrier. Figs. 8(a) and 8(b) are plan and side views showing another arrangement of the connecting section composed of a tape carrier. Fig. 9 is a plan view showing an IC card in which a tape carrier is used. Fig. 10 is a plan view showing an IC card of another embodiment in which a tape carrier is used. Fig. 11 is a schematic illustration showing an arrangement of the conventional IC card. THE MOST PREFERRED EMBODIMENT FOR CARRYING OUT THE INVENTION By referring to the appended drawings, the most preferred embodiment of the present invention will be explained as follows. Fig. 1 is a view showing the first embodiment of the present invention. The IC card of this embodiment is composed in such a manner that the plane coil 12, which composes an antenna, and the semiconductor element 14 are interposed between, and sealed by, two sheets of resin films 10, so that the overall IC card is formed into a card-shape. The plane coil 12 is made by etching or punching a sheet of metal such as copper. The semiconductor element 14 and the plane coil 12 are electrically connected to each other by bonding wires 16 which connect electrode terminals of the semiconductor element 14 to terminals 12a of the plane coil 12. Figs. 2 and 3 are respectively an enlarged plan view and an enlarged side view showing a connecting section in which the semiconductor element 14 and the terminals 12a of the plane coil 12 are connected to each other, wherein this connecting section is the most characteristic portion in the structure of the IC card of this embodiment. Reference numeral 12b is a conductor composing the plane coil 12. The plane coil 12 is formed into a configuration in which the conductor 12b is wound a plurality of times in the same manner as that of the conventional IC card shown Fig. 7. A method of manufacturing the plane coil 12 by punching a metallic sheet is advantageous as follows. According to the above method, it is possible to form a narrow conductor 12b, that is, the width of the conductor 12b can easily be reduced. Therefore, it is possible to form a configuration in which the conductor 12b is wound a large number of times. The above plane coil 12 can easily be mass-produced when it is successively punched in a plurality of manufacturing stages. For the above reasons, as compared with the conventional method in which a covered wire is wound a plurality of times, it is possible to greatly reduce the manufacturing cost by adopting the above punching method. In this connection, of course, it is possible to form the plane coil by etching a metallic sheet. When a very narrow conductor is to be formed, the etching method is effective. As shown in Fig. 2, this embodiment is characterized in that: the semiconductor element 14 is arranged in the coil width in which the conductor 12b of the plane coil 12 passes; and the conductor 12b is arranged outside the semiconductor element 14 so that the conductor 12b cannot overlap the semiconductor element 14. The reason why the above arrangement is adopted is that the terminals 12a, 12a on both sides of the plane coil 12 cannot be simultaneously connected to the electrodes of the semiconductor element 14 because the size of the semiconductor element 14 is too small. Another reason is that even if the conductor 12b is arranged to avoid overlapping the semiconductor element 14, the characteristic of the plane coil 12 is not effected, because the size of the semiconductor element 14 is small. When the semiconductor element 14 and the conductor 12b of the plane coil 12 do not overlap each other as described in this embodiment, the overall thickness of the IC card is determined by the respective thickness of the plane coil 12 and the semiconductor element 14. Therefore, the arrangement of this embodiment is advantageous in that the thickness of the IC card can be reduced. In this connection, the semiconductor element 14 is electrically connected to the terminals 12a of the plane coil 12 by bonding wires 16, the outer circumferential faces of which are covered with coating material having an electrically insulating property. The reason why the covered bonding wire 16 is used is described as follows. It is necessary to prevent the occurrence of an electrical short circuit would be caused if the bonding wires 16 came into contact with an intermediate portion between the electrodes of the semiconductor element 14 and the terminals 12a. When there is no possibility of the occurrence of an electrical short circuit between the bonding wires 16 and the conductor 12b, of course, it is unnecessary to use the bonding wires 16 covered with an electrically insulating material. For example, when a method is adopted in which the insulating layer 13 is formed by making an electrical insulating film adhere onto a surface of the thin wall thickness portion 12c as shown in Fig. 4(a), or when a method is adopted in which the insulating layer 13 is formed by coating resin having an electrical insulating property on an inner bottom face of the thin wall thickness portion 12c as shown in Fig. 4(b), it is possible to conduct wire bonding by using bonding wires which are not covered with an electrically insulating material. According to the wire bonding method in which the covered bonding wires 16 are used, bonding is carried out as follows. The bonding wire is pressed against a bonding face and given a frictional force by means of ultrasonic oscillation. Therefore, the covering material is separated from the bonding wire, and the thus exposed bonding wire is bonded to the bonding face. Therefore, in the case where wire bonding is conducted in such a manner that the bonding wires cross the conductor 12b as shown in this embodiment, the above method is preferably used. In the wire bonding method, there is provided a method of bonding in which an arc formed by the bonding wire is not so high which is like the wedge bonding method. However, in order to draw out the bonding wire, the bonding wire protrudes upward so that it is a little higher than the bonding portion at which the bonding wire is drawn out. In this embodiment, in order to prevent the bonding wire 16 from protruding from the face of the conductor 12b, a portion of the conductor 12b, through which the bonding wire 16 passes in the case of bonding, is subjected to coining so as to reduce the thickness of the conductor 12b. Fig. 3 is a view showing a state of the thin wall thickness portion 12c in which the conductor 12b has been subjected to coining. In Fig. 2, reference mark C represents a range in which the thin wall thickness portion 12c is formed. In Fig. 3, reference mark H represents a thickness of the conductor 12b, and reference mark L represents a thickness of the conductor 12b in a portion in which the thin wall thickness portion 12c is formed. Since the thickness of a metallic sheet, which is formed into a pattern by punching, is approximately 100 µm and the thickness of the semiconductor element 14 is approximately 50 µm, the thickness L of the conductor 12b is reduced to about 50 µm by means of coining. Since the thin wall thickness portion 12c is formed as described above, it is possible to conduct bonding so that the bonding wire 16 can be accommodated in the thin wall thickness portion 12c. Therefore, the semiconductor element 14 and the bonding wire 16 can be accommodated in the thickness range of the plane coil 12. As shown in Fig. 2, in this embodiment, the conductor 12b is subjected to coining, and a range in which the thin wall thickness portion 12c is formed is made wider than a range through which the bonding wires 16 pass, that is, the width of a range in which the thin wall thickness portion 12c is formed is made to be C. The reason is that coining must be conducted by one punching operation because the plane coil 12 is manufactured by punching. Of course, coining may be conducted only along the routes in which the bonding wires 16 pass. Figs. 5 and 6 are schematic illustrations showing the second and third embodiments of the IC card. In these embodiments, the semiconductor element 14 is arranged at a position which is separate from the width range in which the conductor 12b composing the plane coil 12 is arranged, that is, the semiconductor element 14 is arranged outside the outer circumferential edge portion of the plane coil 12 or inside the inner circumferential edge portion of the plane coil 12, and the terminals 12a of the plane coil 12 and the semiconductor element 14 are connected with each other by means of wire bonding in such a manner that the bonding wires cross the conductor 12b. In the embodiment shown in Fig. 5, the terminals 12a on both sides of the conductor 12b are subjected to coining, so that the thickness of the terminals can be reduced. At the same time, a portion of the conductor 12b in which one of the bonding wires 16a crosses the conductor 12b is subjected to coining, so that the thin wall thickness portion 12c can be formed. Concerning the bonding wire 16a which crosses the conductor 12b and is connected with the terminal 12a, wire bonding is conducted in such a manner that the bonding wire 16a passes over the portion in which the thin wall thickness portion 12c is formed. Therefore, it is possible to accomplish the connection so that the bonding wire does not protrude from a surface of the conductor 12b. In the embodiment shown in Fig. 6, the thin wall thickness portion 12c is formed in the conductor 12b in accordance with a portion in which the two bonding wires 16 for connecting the terminals 12a of the plane coil 12 with the semiconductor element 14, and the bonding wires 16 are arranged crossing the thin wall thickness portion 12c. In this embodiment, the conductor 12b of the plane coil 12 and the semiconductor element 14 do not overlap each other. Therefore, it is possible to reduce the overall thickness of the IC card. Accordingly, when the thin wall thickness portion 12c is formed in a portion in which the bonding wires pass, the bonding wires can be accommodated in the thickness of the plane coil 12. As described above, in the IC card of the present invention, the plane coil 12 and the semiconductor element 14 are arranged so that they do not overlap each other, and further the thin wall thickness portion 12c is formed in a portion of the conductor 12b in which the bonding wires 16 for connecting the terminals 12a of the plane coil 12 with the electrodes of the semiconductor element 14 pass, so that the bonding wires 16 do not protrude from a surface of the conductor 12b. Due to the above structure, the overall thickness of the IC card can be reduced. When the plane coil 12 and the semiconductor element 14 are connected to each other by means of wire bonding, it becomes possible to electrically connect the plane coil 12 with the semiconductor element 14 irrespective of the size and the arrangement position of the semiconductor element 14. When the terminals 12a of the plane coil 12 and the semiconductor element 14 are connected with each other by means of wire bonding, the semiconductor element 14 is hung by the bonding wires 16. Therefore, under the condition that the semiconductor element 14 is wire-bonded, it can be easily conveyed together with the plane coil 12. Instead of the bonding wires, metallic ribbons may be used for connecting the semiconductor element 14 with the terminals 12a of the plane coil 12. Compared with the bonding wires, the metallic ribbons are advantageous in that the electrical resistance is low. Figs. 7(a) and 7(b) are respectively a plan view and a side view showing an embodiment of the connecting section in the case where a tape carrier (TAB tape) is used as the electrically connecting means instead of bonding wires. In this embodiment, the tape carrier 20 is composed in such a manner that two substantially parallel conductor patterns 22 are formed on an insulating resin film 21. At a position of the semiconductor element 14, an opening 21a, the size of which is larger than the plane size of the semiconductor element 14, is formed on the resin film 21, and the two conductor patterns 22 are arranged above the opening 21a. On one side, end portions of the two conductor patterns 22 extend to the same portion, and the two conductor patterns 22 are electrically connected to the electrodes of the semiconductor element at the position of the opening 21a. On the other side, an end portion of one of the conductor patterns 22 is short, and an end portion of the other conductor pattern 22 is long. These end portions are respectively connected to the outside and the inside terminal of the plane coil 12 in the case where the semiconductor element 14 is arranged inside the plane coil 12. In this embodiment, the semiconductor element 14 is connected to the conductor pattern 22 so that the semiconductor element 14 can be located on the same side as that of the resin film 21 with respect to the conductor pattern 22. Accordingly, this embodiment is preferably applied to a case in which the thickness of the semiconductor element 14 is small. In this connection, reference numeral 23 is a layer of an insulating resist which is used for insulating the conductor 12b of the plane coil 12. Figs. 8(a) and 8(b) are respectively a plan view and a side view showing another embodiment of the connecting section in the case where a tape carrier is used. A different point of this embodiment from the embodiment described above is that the semiconductor element 14 is connected to the conductor pattern so that the semiconductor element 14 can be located on the opposite side to the resin film 21 with respect to the conductor pattern. Accordingly, there is provided no opening 21a unlike the embodiment described before. In this embodiment, the semiconductor element 14 is located on the side of the plane coil 12. Therefore, even if the thin wall thickness portion is not provided in the conductor 12b of the plane coil 12, there is a possibility that the semiconductor element 14 is sufficiently accommodated in thickness range c of the conductor 12b of the plane coil. In this connection, when the semiconductor element 14 cannot be firmly held, a reinforcement member 24 may be arranged in the periphery of the semiconductor element 14. Figs. 9 and 10 are views showing embodiments of the connecting section in the case where a tape carrier is used as the electrical connecting means instead of bonding wires. In these embodiments, the position of the semiconductor element shown in Fig. 9 corresponds to the position of the semiconductor element shown in Fig. 2, and the position of the semiconductor element shown in Fig. 10 corresponds to the position of the semiconductor element shown in Fig. 6. Concerning the arrangement of connection for connecting the tape carrier 20 with the semiconductor element 14, any of the arrangements shown in Figs. 7(a) and 7(b) and the arrangements shown in Figs. 8(a) and 8(b) may be adopted. In this connection, the IC card of each embodiment of the present invention described above uses the plane coil 12 formed by press forming a metallic sheet. When coining is conducted simultaneously when the metallic sheet is punched so as to form the conductor 12b, the thin wall thickness portion 12c can be easily formed in the conductor 12b. The above method is advantageous in that coining and punching can be carried out in the same manufacturing line. INDUSTRIAL APPLICABILITY According to the IC card of the present invention which is composed as described above, it is possible to electrically connect the plane coil to the semiconductor element irrespective of the width of the plane coil and the size of the semiconductor element. Since the thin wall thickness portion is provided in accordance with a portion of the conductor in which the bonding wires cross the conductor, the thickness of the connecting portion, in which the plane coil is connected with the semiconductor element, can be reduced to the substantially same thickness as that of the plane coil. Therefore, the thickness of the IC card can be appropriately reduced. When a metallic thin sheet is punched so as to manufacture a plane coil, the productivity of the plane coil can be enhanced and the manufacturing cost can be effectively decreased. DESCRIPTION OF REFERENCE NUMERALS 10 resin film 12 plane coil 12a terminal 12b conductor 12c thin portion 13 insulating layer 14 semiconductor element 16 bonding wire 20 tape carrier 21 insulating film 22 conductor pattern 23 insulating resist 24 reinforcement material 100 plane coil 102 semiconductor element

Claims: A plane coil (12) for an IC card, the plane coil comprising a conductor (12b) wound in a plane and having terminals (12a) at respective ends; wherein the terminals (12a) are electrically connected to a semiconductor element (14) via electrical connecting means (16); characterised in that a portion of the conductor is formed as a thin wall thickness portion (12c) through which the electrical connecting means (16) can pass without protruding from a range of the thickness of the conductor. An IC card comprising: a semiconductor element (14) having electrodes; a plane coil (12) according to claim 1; an electrical connecting means (16) for electrically connecting the terminals (12a) at the respective ends of the plane coil (12) to the electrodes of the semiconductor element (14); and, resin films for sealing the semiconductor element (14) , plane coil (12) and connecting means (16) when they are interposed between the resin films, wherein the thickness of the semiconductor element (14) is smaller than the thickness of the plane coil (12), the semiconductor element (14) being arranged adjacent the plane coil (12) so that the semiconductor element does not coincide with the conductor (12b) of the plane coil (12). The IC card (12) according to claim 2, wherein the conductor (12b) is formed by punching or etching a metallic sheet, and the thin wall thickness portion (12c) is formed in a predetermined portion of the conductor (12b). The IC card according to claim 2 or claim 3, wherein the electrical connecting means are bonding wires (16), and bonding connection is made by connecting end portions of the bonding wires (16) between the terminals (12a) of the plane coil (12) and the electrodes of the semiconductor element (14). The IC card according to claim 4, wherein an outer circumferential surface of the bonding wire (16) is covered with an electrically insulating covering material. The IC card according to claim 2 or claim 3, wherein the electrical connecting means is composed of a film carrier (20) in which an electrical conductive pattern (22) is formed on an insulating film, and the electrical conductive pattern (22) is electrically connected with the terminals (12a) of the plane coil (12) and the electrodes of the semiconductor element (14). The IC card according to any one of claims 2 to 6, wherein the semiconductor element (14) is arranged between adjacent windings of the plane coil (12). The IC card according to any one of claims 2 to 6, wherein the semiconductor element (14) is arranged either outside the outer winding of the plane coil (12) or inside the inner winding of the plane coil. The plane coil (12) according to claim 1, or the plane coil (12) of the IC card according to any one of claims 2 to 8, wherein an insulating layer (13) is formed on a surface of the thin wall thickness portion (12c).

Inventors: AKAGAWA M, ITO D, AKAGAWA, M., ITO, D., AKAGAWA, M. Shinko Electric Ind. Co.,Ltd, ITO, D., Shinko Electric Industries Co. Ltd.
Applicants: SHINKO ELECTRIC IND CO, SHINKO ELECTRIC INDUSTRIES CO. LTD.
Application year: 1999
Main classification: G06K19
IPC codes: G06K19, H01F5