IC card and a method for the manufacture of the same

#This invention relates to an IC card and a method for manufacturing the IC card, which has an IC module incorporating an IC chip that processes or stores data, can exchange data with external devices, and can be carried and used as a cash card, credit card, identification card or the like.

#A so-called IC card, which incorporates an IC module containing an IC chip having a microcomputer and memories therein and having a series of connection terminals for exchanging data with external devices buried in a card base, is widely known, and its standardization is in process at the ISO (International Organization for Standardization). In comparison with conventional magnetic stripe cards, since such IC cards have a larger memory capacity and are superior in security, practical usages are considered in many fields such as financial businesses, medical institutes and personal identification. The portability of the IC cards are greatly advantageous like that of conventional magnetic stripe cards. Therefore, to put the IC cards into practical use, the reliability must be securely guaranteed in the environment where the IC cards are used, that is, resistance to bending of IC card and protection of the incorporated IC chip from external stresses. Nowadays, this is an important problem.

#As a conventional example, a sectional view of an IC card in Japanese Laid-open Patent Publication No. 58-92597 is shown in FIG. 8. This IC card is constructed by an IC module 32 incorporating an IC chip and having connection terminals 34 with external devices which are adhered inside of a concave 33 formed in a specified position on a card base 31 with an adhesive 35. An IC card having such a construction is produced by punching out a card base 31 in a desired size, forming a concave 33 with a size similar to an IC module 32 in a desired position, disposing the IC module 32 inside of the concave 33 of the card base 31 by using the adhesive 35 in such a way that the surface of the connection terminals 34 is flush with the surface of the card base 31.

#FIGS. 1a and b are a top view showing an IC card of this invention and a sectional view along line A--A' of FIG. 1a, FIG. 2 is a sectional view showing an IC module used in an IC card of the invention, FIGS. 3, 4 and 5 are sectional views showing other IC cards of the invention, FIGS. 6a, b and FIGS. 7a to d are sectional views showing methods for manufacturing an IC card of the invention, and FIG. 8 is a sectional view showing a conventional IC card.

#Referring to the drawings, one of the embodiments of the invention is described in detail below. FIGS. 1 and 2 show one embodiment of the invention. As shown in FIG. 2, an IC module 3 incorporating an IC chip 10 and having a series of connection terminals 2 to exchange data with external devices is positioned in a first concave 9 that is formed in a specified position of a card base 1 shown in FIG. 1 in such a manner that the surface of each connection terminal 2 is flush with the surface of the card base 1. The IC module 3 in such a state is adhered to the inside bottom part of the first concave 9 by means of an adhesive 7. The card base 1 is composed of two center cores 5a and 5b made of white colored rigid vinyl chloride resin and two over-sheets 4a and 4b made of transparent vinyl chloride resin that are disposed on the surfaces of the center cores 5a and 5b, respectively. Between the center core 5a and the over-sheet 4a, and between the center core 5b and the over-sheet 4b, although not shown in FIG. 1a, desired letters and patterns 6a and 6b which are visible through the over-sheets 4a and 4b are formed by a printing technique. The thickness of the center cores 5a and 5b are both 0.35 mm, that of over-sheets 4a and 4b are both 0.03 mm, the overall thickness of the card base 1 is 0.76 mm, and the overall dimensions are the same as credit cards. As shown in the sectional view in FIG. 2, the IC module 3 used in this IC card comprises a connection terminal 2 composed of a metallic thin plate, one surface of which is exposed outside and on the other surface an IC chip 10 that processes or stores data is mounted with an insulating adhesive 11. The IC chip 10 is connected to the connection terminal 2 by a metallic wire 12, and these members are covered with a sealing resin 13 made of an epoxy resin. By the transfer molding method, the IC chip 10 and the peripheral members (adhesive 11, metallic wire 12, sealing resin 13 and connection terminal 2) are molded into one body. The overall dimensions of this IC module 3 are 10.2.times.12.4 mm, and the thickness is 0.59 mm. The IC chip 10 works by connecting five out of six connection terminals 2, which are exposed on the surface of the IC module 3 as shown in FIG. 1a, to an external device.

#As shown in FIG. 1b, the inside surface of the first concave 9 formed in the card base 1 continuously inclines inward toward the inside bottom surface of this first concave 9, and between the inside surface of the first concave 9 and the outside surface of the IC module 3 adhered to the inside bottom surface of the first concave 9, there is formed an inclined gap 8 which is wider at the inner upper part of the first concave 9 and narrower at the inner lower part of the first concave 9. In an IC card having such a construction, in the case that the both sides of the card base 1 are bent downward, the gap 8 between the inside surface of the first concave 9 and the outside surface of the IC module 3 simply opens and the inside surface of the first concave 9 does not press the outside surface of the IC module 3 inward, so that a bending stress does not work on the IC module 3. Reversely, in the case that the both sides of the card base 1 are bent upward, the inside surface of the first concave 9 changes positions more at the inner upper part of the first concave 9 and less at the inner lower part thereof, centering around the boundary portion 14 of the said inside surface and the said inside bottom surface, and comes very close to the outside surface of the IC module 3. Since the inclined gap 8 which is wider at the inner upper part of the first concave 9 and narrower at the inner lower part is formed between the inside surface of the first concave 9 and the outside surface of the IC module 3, so long as the card base 1 is exceedingly bent, the inside surface of the first concave 9 and the outside surface of the IC module 3 do not directly contact. Therefore, a bending stress of the card base 1 does not work on the IC module 3. In a portion of the card base 1 that is close to the boundary portion 14 of the inside surface and the inside bottom surface of the first concave 9, a tension or a bending stress which may be created in the case that the inside surface of the inner upper part of the first concave 9 and the outside surface of the IC module 3 contact each other is not generated. Thus, even if both sides of the card base 1 are bent either upward or downward, the IC module 3 and the card base 1 are protected from the bending stress.

#As a result of our various experiments, it is proved that by forming the inside surface of the first concave 9 at an inclination of 10 deg., against the perpendicular and setting the internal angle between the inside surface of the first concave 9 and the outside surface of the IC module 3 at 10 deg., the IC module 3 and the card base 1 are protected at a practical level against a bending of the IC card. The inner dimensions of the inside bottom surface of the first concave 9 are set at 10.28.times.12.48 mm, taking the allowance of the inner dimensions and the allowance of the outer dimensions of the IC module 3 in consideration, and the depth of the first concave 9 is set so that the thickness of the remaining part of the card base 1 at the lower inside bottom surface of the first concave 9 becomes 0.15 mm. The thickness of the remaining part of the card base 1, 0.15 mm, is composed of a thickness 0.03 mm of the over-sheet 4b and the remaining thickness 0.12 mm of the center core 5b, and this composition is an important factor that determines durability and strength of the card base 1 against bending, as the thickness of the card base 1 is the smallest.