Molded IC card

An IC card includes a thin plate forming an external surface of the card, a circuit board formed on an internal surface of the thin plate, and a frame surrounding peripheries of the thin plate and the circuit board. A space defined by the frame and the surface plate is filled with molded resin. A portion of an inner peripheral surface of the frame projects into the resin. The molded resin completely covers a surface of the circuit board and integrates the frame and the thin plate.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to structures of an IC card in which a 
microcomputer and/or an IC memory are embedded in a plate such as a 
credit-card-sized plate. 
2. Description of the Background Art 
FIGS. 9A and 9B show a conventional IC card. FIG. 9A is a plan view of the 
IC card of a non-contact type, and FIG. 9B is a structural cross section 
taken along line C--C in FIG. 9B. 
The IC card has the same size as that of credit cards, and incorporates an 
integrated circuit(s) such as a microprocessor and/or a memory. The IC 
card has advantages that a memory capacity is larger than those of a 
magnetic card or the like, and that information can be altered. 
Referring to FIGS. 9A and 9B, an IC card 1 includes a pair of upper and 
lower casings 101 and 102, and a circuit board 4 assembled in the casings 
101 and 102. On a surface of the circuit board 4, there are formed an IC 
(integrated circuit) device 5 as well as an interconnection pattern 9 
connected to the IC device 5. The circuit board 4 is fixed to an internal 
surface of the lower casing 102. A space is formed between the circuit 
board 4 and an internal surface of the upper casing 101, and between the 
board and the internal surface of the lower casing 102. 
FIGS. 10A and 10B illustrates a conventional IC card of another type. FIG. 
10A is a structural plan view of the IC card of a contact type having an 
electrode terminal for an external connection, and FIG. 10B is a 
structural cross section taken along line D--D in FIG. 10A. The IC card of 
this type includes an electrode terminal 41 formed on a portion of the 
surface of the lower casing 102. The electrode terminal 41 is electrically 
connected to the interconnection pattern 9 on the circuit board 4 via a 
through hole 42. 
The IC cards 1 of the non-contact and contact types described above have 
spaces 11 in casings 10 made from plastics. The space 11 must have the 
size large enough to prevent contact between the upper casing 101 and the 
IC device 5 when the card 1 is deformed to a large extent by an external 
force. Due to this large space 11, the IC card 1 cannot be made thin. 
A strength of, particularly, the upper casing 101 depends only on the 
thickness of the upper casing 101. Therefore, in order to increase the 
strength of the IC card 1, the upper casing 101 and the lower casing 102 
must have large thicknesses, respectively. This further impedes the 
reduction of thickness of the IC card. 
Further, in the prior art IC card, moisture may enter through a gap between 
the upper and lower casings 101 and 102. Therefore, the prior art IC card 
has a problem of low environmental resistivity. 
Meanwhile, IC cards having resin coating on the integrated circuit boards 
provided with the IC devices have been known. 
U.S. Pat. No. 4,746,392 has disclosed an IC card in which an integrated 
circuit module is fitted into a portion of a stack of films which forms a 
card body. This card body is formed of a stacked structure of films 
without a frame member surrounding peripheries of these films. The card 
body has a concave portion. An IC module is fitted into this concave 
portion, and the gap between the IC module and the concave portion is 
filled with resin. This resin member covers only the periphery of the IC 
module, and does not serve as a structural member for the card body. 
This IC card further employs a film covering a surface of the resin. 
Therefore, employment of this surface film impedes the reduction of 
thickness of the IC card. Further, since the card body is formed of the 
stacked structure of thin films, the card has low strength at its end or 
edge portions. 
SUMMARY OF THE INVENTION 
It is an object of the invention to reduce a thickness of an IC card. 
It is another object of the invention to improve strength of an IC card. 
It is still another object of the invention to provide an IC card having 
structures which enables easy manufacturing of an IC card. 
An IC card according to the invention comprises a surface plate forming one 
surface of the IC card, and a circuit board attached to an internal 
surface of this surface plate and incorporating a semiconductor element. 
Further, the IC card comprises a frame which extends along a whole 
peripheral edge of the surface plate and surrounds the surface plate and 
the circuit board. A space defined by the frame and the surface plate is 
filled with a filler of which surface forms a rear surface of the IC card. 
A portion of an inner peripheral surface of the frame projects into the 
filler. 
The foregoing and other objects, features, aspects and advantages of the 
present invention will become more apparent from the following detailed 
description of the present invention when taken in conjunction with the 
accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
An IC card of a first embodiment of the invention is illustrated in FIGS. 
1A and 1B. The IC card 1 includes a thin plate 3 made of resin, a circuit 
board 4 fixed to a surface of the thin plate 3, a frame 2 surrounding 
whole peripheries of the thin plate 3 and the circuit board 4, and a 
molded resin 7 filled inside the frame 2. Other surface of the thin plate 
3 forms a top surface of the IC card 1. A surface of the molded resin 7 
forms a rear or bottom surface of the IC card 1. Further, the frame 2 
principally forms side surfaces of the IC card I. 
The thin plate 3 is formed of a thin premolded plate of resin. The circuit 
board 4 is fixed to an internal surface of the thin plate 3. A 
predetermined circuit pattern is formed on a surface of a circuit board 4. 
The surface of the circuit board 4 also bears an IC device 5 and a chip 
part 6 which have functions such as a memory function and an operation 
function. 
Now, structures of the frame 2 will be described with reference to FIGS. 
2A-2D. The frame 2 has a rim-like body 2b and a rib or inward projection 
2a projected from an inner peripheral surface of the frame body 2b. The 
rib 2a is located at a substantially central position of the body 2b of 
the frame 2 with respect to a direction of the card thickness. The rib 2a 
is in contact with the surface of the circuit board 4 in a finished card. 
The rib 2a is continuously formed along the inner periphery of the frame 
body 2b, and has a section which is preferably of a dumbbell-shape, as 
shown in FIG. 2C, or of a square shape, as shown in FIG. 2D. Of course, 
other sectional shapes may be employed. 
Returning to FIG. 1B, the molded resin 7 completely fills a space formed 
between the frame 2, thin plate 3 and circuit board 4. This molded resin 7 
has a protection function for protecting circuits formed on the circuit 
board 4 and a function as a strength member in the IC card. That is, the 
complete covering of the surface of, the circuit board 4 with the molded 
resin 7 improves an environmental resistivity such as a water proof. 
Further, the rigidity of the molded resign 7 itself resists an external 
force applied to the IC card 1 to restrict the application of the external 
force onto the circuit board 4. It is preferable to form all of the frame 
2, thin plate 3 and molded resin 7 from the same material such as liquid 
crystal polymer. However, these may be formed of different kinds of resin. 
Now, manufacturing method of the IC card shown in FIG. 1B will be described 
with reference to FIGS. 3A-3D. 
First, as shown in FIG. 3A, the thin plate 3 is laid on a lower die 8a of a 
metal mold 8. Further, the circuit board 4 is laid on the surface of the 
thin plate 3. The circuit board 4 has the predetermined circuit pattern, 
IC device 5 and chip parts 6 which are formed in advance on the surface 
thereof. 
Then, as shown in FIG. 3B, the frame 2 is fitted into a concave in the 
lower die 8a. 
Then, as shown in FIG. 3C, the upper die 8b is lowered to close the mold 8. 
In this condition, the external surface of the frame 2 is in tight contact 
an internal surface of the mold 8. 
Then, as shown in FIG. 3D, liquid resin is introduced into the mold 8 
through a gate 9 formed in the upper die 8b. The resin is supplied to fill 
completely the space inside the mold 8. Thereafter, the resin is hardened, 
and thus the frame 2, thin plate 3, circuit board 4 and molded resin 7 are 
integrated. The mold 8 is opened to release the IC card 1. 
As described above, the IC card 1 is manufactured by the integration of the 
respective components, i.e., the frame 2, thin plate 3 and circuit board 4 
by the molded resin 7. Therefore, neither bonding step nor stacking step 
is required, which simplifies the manufacturing steps. Further, the rib 2a 
provided in the frame 2 reliably prevents separation of the molded resin 7 
and the frame 2 from each other. 
Then, a second embodiment of the invention will be described below. 
Referring to FIG. 4, the frame 2 of the IC card of the second embodiment 
is provided at its inner peripheral surface with the rib 2a which has a 
plurality of recesses 211. FIG. 5 illustrates the frame 2 and the circuit 
board 4 assembled therein. The recesses 211 provided in the rib 2a form 
gaps 21 between the frame 2 and the circuit board 4. The gaps 21 serve 
such that a space between the frame 2 and the thin plate 3 is sufficiently 
filled with the introduced resin through these gaps 21. 
Further, a third embodiment of the invention will be described below. As 
shown in FIG. 6, the frame 2 of the third embodiment is provided at 
several portions of the rib 2a with through holes 22. FIG. 7 shows the 
frame 2 and the circuit board 4 assembled therein. The through holes 22 in 
the rib 2a are located substantially at a boundary region between the 
frame 2 and the circuit board 4. These through holes 22 serve to fill 
completely the space with the resin, similarly to the recesses 211 shown 
in FIG. 4. 
Then, modifications of the first to third embodiments will be described 
below. While the above first to third embodiments are described with 
respect to a so-called non-contact type in which external electrode 
terminals of the IC cards are not exposed at the external surfaces, these 
embodiments can be applied to the IC cards of a contact type having 
exposed external electrode terminals. FIG. 8A illustrates the structures 
of the IC card, in which the electrode terminal 41 extending from the 
circuit board 4 is exposed at the surface of the IC card through a space 
between the frame 2 and the thin plate. FIG. 8B illustrates the IC card 
having structures in which the thin plate 3 is provided at a predetermined 
position with an opening 31 through which the external electrode terminal 
41 extending from the circuit board 4 is exposed on the card surface. 
As described above, the IC card according to the invention is formed of the 
frame 2, thin plate 3 and circuit board 4 which are integrated by the 
molded resin 7. The frame 2 improves the strength and shock resistance at 
the outer peripheral edge of the IC card. The molded resin improves the 
environmental resistivity such as the water proof for the circuits formed 
on the circuit substrate. The rib formed at the inner periphery of the 
frame reliably fixes the frame and the molded resin together. Further, if 
the same configurations of the frames are employed, production can be 
performed with the common molds, independent of types of the circuits 
formed on the circuit board. Therefore, the manufacturing steps can be 
simplified, resulting in an improved productivity. 
Further, the IC card according to the invention is manufactured by filling 
the space defined by the frame and the thin plate with the molded resin. 
Therefore, the thicknesses of the IC cards are determined to be constant 
by the configurations of the metal mold which encloses the frames. 
Thereby, the IC cards having a small and uniform thickness can be 
produced. 
Although the present invention has been described and illustrated in 
detail, it is clearly understood that the same is by way of illustration 
and example only and is not to be taken by way of limitation, the spirit 
and scope of the present invention being limited only by the terms of the 
appended claims.