IC card

Abstract: An IC card has a circuit board 11 with terminals 13 on one face at one end, and an IC module 1 on the other face. The terminals are on a portion 12 of the board which is raised above the surface of the rest of the board. Resin is injection molded round the circuit board and IC module so that these are completely incapsulated in resin on both sides to form a card body 14, with the exception of the raised terminal portion 12 and the terminals 13 on it. To form the resin body 14, the circuit board and IC module are placed in a mold cavity in which they are located by means of the raised terminal portion 12 and narrow holding projections 16b while the rest of the circuit board and IC module are entirely surrounded by molding space. The holding projections 16b serve to form guide grooves 14a in the resin body 14.

Description: BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates to an IC card formed by mounting an IC (Integrated Circuit) on a circuit board and molding them with resin. DESCRIPTION OF THE RELATED ART Fig. 1A is a plan view which illustrates a conventional IC card, and Fig. 1B is a cross-sectional view which illustrates the same. An integrated circuit 1 (abbreviated as "IC" hereinafter) is mounted on a reverse side of a circuit board 2 and connected to a circuit (not shown) formed on the same side of this circuit board 2. A plurality of electrode terminals 3 for establishing an electrical connection between the IC 1 and outer equipment is disposed at an end portion of the inverse side of the circuit board 2, that is, the obverse side of the same, these electrode terminals 3 are connected to the above circuit formed on the inverse side of the circuit board 2. Thus-formed circuit board 2 is fitted and bonded, with an adhesive (not shown), within a recessed portion formed in a card base body 4 composed of molding synthetic resin, such as to expose the obverse side of the circuit board. In an another method for assembling of the IC card, as shown in Figs. 2A and 2B, the thus-formed circuit board 2 is molded by sealing with resin as follows: first, the circuit board 2 is, as shown in Fig. 2A, disposed within a recessed portion 5a of the lower mold 5 such that the side on which the electrode terminal 3 is disposed is allowed to face downward and the two ends thereof are respectively supported by a pair of positioning projections 5b. Then, the circuit board 2 is fixed within the recessed portion 5a by reducing pressure through a suction hole 5c. Next, as shown in Fig. 2B, an upper mold 6 is secured to the lower mold 5. Then, molten synthetic resin is introduced through a runner 5d and injected into the recessed portions 5a and 6a. Thus, as shown in Fig. 1, an IC card in which the circuit board 2 is embedded in the card base body 4 as to be integrated with the latter and the obverse side of the circuit substrate 2 is allowed to appear. In the conventional IC card formed as described above, a problem rises in the type of an IC card formed by adhering the circuit board 2 to which the IC 1 is secured to the reverse side of this circuit board 2 to the recessed portion in the card base body 4 which has been previously molded, the problem being such as a deterioration of the adhesion and water invasion from outside to the adhered portion. On the other hand, an IC card formed by integrally embedding the one side of the circuit board 2 with synthetic resin rises a problem in that the circuit board 2 cannot be readily secured to the mold. In addition, a large portion of one surface of the IC card 1 is covered with the obverse surface of the circuit board 2, which deteriorates the quality in terms of appearance of the IC card. It as well causes a problem in that it is difficult to apply a print or the like to the surface, and causes a limitation in terms of design of the IC card. Another problem rises, due to the fact that the surface of the circuit board 2 is allowed to appear on one surface of the card base body 4, in that the card can be warped due to the difference between the thermal expansion coefficients of the circuit board 2 and the card base body 4. As a result, a bond strength between the circuit board 2 and the body 4 deteriorates. EP-A-0 254 444 discloses an integrated circuit module in which the circuit board is completely encapsulated on both sides, but this arrangement is complicated to utilise in an IC card. EP-A-0 297 991 discloses an IC card which is covered with resin on one side only and which, therefore, suffers from many of the above problems. EP-A-0 277 854 discloses and IC card in which the circuit board is encapsulated, however the card must be manufactured by a suction technique similar to that described above. As a result, it is not easy to secure the circuit board in the mould during manufacture. SUMMARY OF THE INVENTION In view of the above-described problems of the conventional IC card, an object of the present invention is to provide an IC card exhibiting advantages that the circuit board can be readily embedded in the card base, further the circuit board does not appear outside of the IC card, any warp of the card can be prevented, a reliability thereof can be improved, any limitation in terms of designing the IC card can be suspended, and the quality of appearance the IC card can be improved. A still further object of the present invention is to provide an apparatus for and a method of manufacturing an IC card of the type described above. According to the present invention there is provided an IC card according to Claim 1, and a method of manufacturing an IC card according to Claim 4. Preferred features of the invention are set out in Claims 2, 3, 5 and 6. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1A is a plan view which illustrates a conventional IC card; Fig. 1B is a sectional view taken along line IB-IB in Fig. 1A; Fig. 2A is a broken side sectional view which illustrates a state where a circuit board is disposed in a lower mold; Fig. 2B is a broken side sectional view which illustrates a state where an upper mold is secured to the lower mold shown in Fig. 2A; Fig. 3A is plan view which illustrate an IC card according to the present invention; Fig. 3B is a sectional view taken along line IIIB-IIIB in Fig. 3A; Fig. 3C is a front elevational view which illustrates the IC card shown in Fig. 3A; Fig. 4A is a broken side sectional view which illustrates a state where the circuit board is secured within the mold; Fig. 4B is a broken front sectional view which illustrates a state where the circuit board is secured within the mold; Fig. 5A is a broken plan view of a circuit board according to another embodiment of the present invention; Fig. 5B is a sectional view taken along line VB-VB in Fig. 5A; Fig. 6 is a broken front sectional view which illustrates a state where the circuit substrate shown in Fig. 5A is secured within the mold; and Fig. 7 is a broken front sectional view which illustrates an essential portion of the IC card whose card base body has been molded by a mold. DESCRIPTION OF THE PREFERRED EMBODIMENT Figs. 3A to 3C are views which illustrate an embodiment of an IC card according to the present invention. Referring to the drawings, a terminal board portion 12 is integrally formed or adhered on an end portion of a circuit board 11 as to become higher than the level of the surface of the circuit board 11. On surface of the terminal substrate portion 12, a plurality of electrode terminals 13 for establishing connections with the outside of the IC card are formed, the plurality of electrode terminals 13 is connected to a circuit (not shown) which is on the reverse side of the circuit board 11. An IC 1 which is connected to the circuit is mounted on the other side, that is, a reverse side of the circuit board 11. A card base body 14 is formed by integrating and embedding the IC 1 and the circuit board 11 by means of injection-molding with synthetic resin after, wherein only the electrode terminal portion 13 of the terminal board portion 12 is allowed to appear the outside of the IC card. A pair of guide grooves 14a having a depth starting from the reverse side of the card base body 14 to the reverse surface of the terminal board portion 12 are formed at the end portions of this card base body 14, and these grooves 14a extend in the direction of insertion and withdrawal of the IC card. This pair of guide grooves 14a are formed by molding by using a mold and capable of preventing erroneous insertion of the IC card inside out into the external equipment. The above-described card base body 14 is molded as shown in Figs. 4A and 4B. The circuit board 11 on which the IC 1 is mounted is put in the bottom portion of a recessed portion 15a of a lower mold 15 so as to allow the electrode terminal 13 to face downward. Then an upper mold 16 is secured to the lower mold 15. As a result, the terminal board portion 12 is pressed down from the reverse side by a pair of pressing projections 16b formed on the both sides of the recessed portion 16a in the upper mold 16. Consequently, the circuit board 11 is held such that the other end portion of the board 11 is floated between the two recessed portions 15a and 16a. Then, the molten synthetic resin is injected through a runner 15b into the two recessed portions 15a and 16a and the mold device is cooled down thereafter. As the result, a card base body 14 which embeds the circuit board 11 so as to allow only the portion of the electrode terminals 13 to appear on the IC card surface can be formed, and an IC card shown in Fig. 3A can be obtained. The guide grooves 14a are formed in the card base body 14 by means of the holding projections 16b of the upper mold 16. Figs. 5A and 5B are views which illustrate a circuit board portion of an IC card according to a second embodiment of the present invention. The IC 1 is mounted on the reverse side of the circuit board 11, while an injected terminal board portion 12 is integrally formed or adhered on an end portion of the obverse side of the circuit board 11. A plurality of electrode terminals 13 are formed on the terminal board portion 12, and a pair of positioning through holes 12a are formed on the both sides of the terminal board portion 12. Thus-fashioned circuit board 11, as shown in Fig. 6, is disposed within the recessed portions 15a and 16a in the upper and lower molds 15 and 16 respectively. In the mold device, the portion of the terminal board 12 is held and secured between the bottom surface of the recessed portion 15a and the holding projection 16b. A pair of positioning pin portions 15c which corresponds to the positioning holes 12a are formed on the both sides of the recessed portion 15a of the lower mold 15 as to be inserted into the positioning holes 12a to position the circuit board 11. Then the molten synthetic resin for molding is injected through a runner (see Fig. 4A) into the recessed portions 15a and 16a in the upper and lower molds 15 and 16, and the mold device is cool down thereafter. As the result, a card base body 14 can be formed so that an IC card can be manufactured, this card base body 14 being formed such that only a portion of the terminal electrodes 13 is allowed to appear on the IC card surface and the portion including the circuit board 11 is embedded in the body 14. The positioning pin portions 15c are formed conically and arranged to be lower than the thickness of the terminal board 12 so that synthetic resin can be introduced into a portion of the positioning hole 12a. As a result, the circuit board 11 can be strongly secured to the card base body 14 by injection molding with the synthetic resin. In the above-described embodiments, although the pair of holding projections 16b are disposed on the both sides of the upper mold 16 to form the pair of guide grooves 14a, the number of the projections, that is the number of the guide grooves, may be increased. As described above and according to the present invention, the terminal board portion is disposed at an end portion of the circuit board to project the surface of the terminal portion over the surface of this circuit board, the electrode terminals are formed on the surface of the terminal board portion, the circuit board portion which provides the IC module on the reverse side thereof is embedded in the card base body by molding with the synthetic resin, and thereby only the electrode terminal portion is allowed to appear. Consequently, the circuit board does not appear outside of the IC card, any warp of the card can be prevented, its reliability can be improved, any limitation in terms of design of the IC card can be suspended, and the quality of appearance can be improved. At least a pair of guide grooves are formed which has the depth starting from the reverse side of the card base body to the reverse side of the terminal board portion and extends in the insertion direction of the IC card, the guide grooves being disposed at both end portions of the card base body. These guide grooves are formed by the holding projections formed in the upper mold. Since the thus-formed holding projections press down the reverse side of the terminal board disposed on the bottom surface of the recessed portion of the lower mold, they can also be used as means for securing the circuit board portion disposed in the mold. As a result, the structure of the securing means can be simplified with respect to that of the conventional securing means, and required works for securing the circuit board portion can be conducted easily. In addition, the structure may be so arranged that a pair of positioning holes are formed on the both sides of the terminal board portion surface of the circuit board, and positioning pins each having a length shorter than the thickness of the corresponding positioning holes are formed for the purpose introducing the synthetic resin for the card base body into a part portion of the positioning holes at the time of the injection molding by using the synthetic resin. As a result, positioning of the circuit board portion can be conducted easily and the coupling of this circuit substrate portion with the card base body can be conducted strongly.

Claims: An IC card comprising: a circuit board (11) including a terminal board portion (12) disposed at an end portion thereof on one side thereof, an IC module (1) being mounted on the other side thereof; at least one electrode terminal (13) on the surface of said terminal board portion (12) and connected to said IC; and a card base body (14) in which by molding by using a synthetic resin, both sides of said circuit board (11) are embedded with said electrode terminal (13) appearing on the outside of said IC card, characterized in that the terminal board portion (12) stands proud of the surface of the said one side of the circuit board (11) and the circuit board (11) is embedded in the molded resin with only the said surface of the terminal board portion (12) remaining exposed. An IC card according to claim 1 further comprising a pair of guide grooves (14a) disposed in the card body at said one end of said card base body (14), formed in the direction in which said IC card is inserted and having a depth running from the side of said card base body (14) opposite to the side of the electrode terminal (13) to the side of said terminal board portion (12) opposite to the electrode terminal (13). An IC card according to claim 2, wherein at least a pair of positioning through holes (12a), running in the terminal board portion (12) from the said surface of said terminal board portion (12) on which the electrode terminal (13) is situated to the side of the terminal board portion (12) opposite to the electrode terminal (13), are formed at the said one end of said terminal board portion (12) of said circuit board (11), said resin forming said card base body (14) being introduced into a respective part portion of each of said positioning holes (12a). A method of making an IC card according to Claim 1, comprising the steps of providing a circuit board (11) with a terminal board portion (12) standing proud in an end region of a first surface of the circuit board (11), mounting an IC module (1) on a surface of the circuit board (11) opposite to the first surface, placing the circuit board (11) and IC module (1) in a mold cavity; and molding an insulating resin material around the circuit board (11) and IC module (1) in the mold cavity; characterised in that, during moulding, the circuit board (11) is positioned in the mould cavity with a proud surface of the terminal board portion (12) in contact with a mold surface and the rest of the circuit board (11) and IC module (1) spaced from the walls of the mold cavity. A method according to Claim 4 of manufacturing an IC card according to claim 2 wherein the mould cavity is defined by a lower mold (15) having a recessed portion (15a), and an upper mold (16) including a recessed portion (16a) and provided with at least two holding projections (16b); one holding projection 16b) being situated at each side of said recessed portion (16a) and being capable of holding said terminal board portion (12) of said circuit board (11) from the side of said terminal board portion (12) opposite to the electrical terminal (13) and serving as a mold for forming a respective one of said guide grooves (14a); said method comprising: a step in which said circuit board (11) is placed on the base of said recessed portion (15a) of said lower mold (15) so as to locate said electrode terminal (13) thereagainst; a step in which said upper mold (16) is secured to said lower mold (15) for the purpose of holding said circuit board (11) such that an end portion of said circuit board (11) opposite to the said one end is spaced from the bases of said two recessed portions (15,16) as a result of pressing said terminal board portion (12) with the holding projections (16b) from the side of said terminal board portion opposite to the electrical terminal (13), and for the purpose of forming the said guide grooves (14a); a step in which molten synthetic resin is injected into a molding space formed by securing said upper mold (16) to said lower mold (15); and a step in which said molding space is cooled down. A method according to claim 5 of manufacturing an IC card according to claim 3 wherein said lower mold (15) comprises at least two positining pins (15c), each having a length shorter than said positioning holes (12a) formed in said terminal board portion (12); said method comprising inserting the pins (15c) into said positioning holes (12a), wherein the circuit board (11) is located in the moulding cavity prior to injection.

Inventors: KODAI SYOJIRO C O KITAITAMI SE, OCHI KATSUNORI C O KITAITAMI S, KODAI, SYOJIRO C/O KITAITAMI SEISAKUSHO OF, OCHI, KATSUNORI C/O KITAITAMI SEISAKUSHO OF
Applicants: MITSUBISHI ELECTRIC CORP, MITSUBISHI DENKI KABUSHIKI KAISHA
Application year: 1989
Main classification: G06K19
IPC codes: H05K3, H05K1, B29C45, G06K19, G11C5, B42D15