IC card and method of making the same

An IC card includes a first cover including a first flat panel portion and a first upright wall portion formed therein adjacent a perimeter of the flat panel portion so as to extend transverse to the flat panel portion, and a second cover including a second flat panel portion and a second upright wall portion formed therein adjacent a perimeter of the flat panel portion so as to extend transverse to the flat panel portion. The first upright wall portion defines a chamber in cooperation with a portion of the first flat panel portion. The first and second covers are mated together with the first and second upright wall portions bonded together in a butt fashion.

BACKGROUND OF THE INVENTION 
1. (Field of the Invention) 
The present invention generally relates to an IC card and, more 
particularly, to the IC card of a non-contact type which has no 
interfacing terminal electrode exposed to the outside, but utilizes 
wireless signals such as electromagnetic waves for communication with 
external system appliances. 
2. (Description of the Prior Art) 
The non-contact type IC cards are not a recent development and are now 
coming into widespread use. One example of the prior art non-contact type 
IC card is schematically shown in FIG. 6 in sectional representation. 
The prior art IC card shown in FIG. 6 is assembled by mounting a circuit 
module 3, including various electronic component parts 2 and a power 
source cell 4 incorporated therein, on a generally rectangular first cover 
10 made of thermoplastic resin, then mounting of an antenna coil 5 for 
selective transmission and receiving data by means of wireless signals to 
and from an external system appliance, applying a thermosetting bond 6 of, 
for example, an epoxy resin to a flat mating face of a peripheral wall 
which is parallel to a plane of a panel body of the first cover 10 and 
which is partially formed with a peripheral recess 13, mounting a 
similarly shaped second cover 20, made of a similar thermoplastic resin, 
onto the first cover 10 with a peripheral protuberance 23 received within 
the peripheral recess 13, and finally heating the assembly to cure the 
thermosetting bond 6 to thereby complete the IC card. 
The prior art IC card so assembled is susceptible to trouble. One of the 
troubles has been found resulting from separation between the first and 
second covers 10 and 20, that is, an insufficient adhesive between the 
first and second covers 10 and 20. 
In order to achieve a sufficient robust bond between the first and second 
covers 10 and 20, a very popular attempt is to increase the mating bond 
areas of the first and second covers 10 and 20. It has, however, been 
found that since increase of the bond areas results in increase of the 
size of the IC card, increase of the bond areas is limited for the IC card 
which requires a compact size and a light-weight feature. 
The inventors of the present invention have examined the bond strength 
between the first and second covers and, as a result thereof, have found 
that, for a given area of surface of contact between the first and second 
covers 10 and 20, the bond strength measured in a direction parallel to, 
that is, in a shearing direction of, the bond areas of the first and 
second covers 10 and 20 is ten or more times that measured in a direction 
perpendicular to any one of the bond areas of the first and second covers 
10 and 20. 
Also, in the manufacture of the prior art IC card, it has often been found 
that during the adhesive between the first and second covers, a deposit of 
the adhesive tends to run outwardly to eventually form bond flashes. Once 
the bond flashes are formed along a joint between the first and second 
covers, an extra process step of removing the bond flashes is required 
during the manufacture of the IC card. 
SUMMARY OF THE INVENTION 
The present invention is based on the above described finding and is 
intended to provide an improved non-contact IC card in which the first and 
second covers are sufficiently bonded together to exhibit an increased 
bond strength with no need to increase the mating bond areas of the first 
and second covers. 
Another important object of the present invention is to provide an improved 
non-contact IC card of the type referred to above wherein no extra step of 
removing the bond flashes such as required in the prior art is required. 
To accomplish these objects, the present invention provides an IC card 
which comprises a first cover including a first flat panel portion and a 
first upright wall portion formed therein adjacent a perimeter of the flat 
panel portion, and a second cover including a second flat panel portion 
and a second upright wall portion formed therein adjacent a perimeter of 
the flat panel portion. The first upright wall defines a chamber for 
storing IC parts in cooperation with a portion of the first flat panel. 
The first and second covers are mated together with the first and second 
upright walls having a joint face bonded together in a butt fashion such 
as a cap-and-cup fashion or an inclined butt fashion. 
The cap-and-cup joint so formed utilizes a peripheral surface of the first 
upright wall to form a plane of joint with a mating peripheral surface of 
the second upright wall that lies at an angle relative to any one of the 
first and second flat panels. Similarly, the inclined butt joint so formed 
utilizes an inclined free end face of the first upright wall remote from 
the first flat panel to form a plane of joint with a corresponding 
inclined free end face of the second upright wall remote from the second 
flat panel that lies at an angle relative to any one of the first and 
second flat panels. In either case, the plane of joint angled relative to 
any one of the first and second flat panels allows a bond component acting 
in the shearing direction relative to the plane of joint to be used as a 
bond strength with which the first and second covers are bonded together. 
Accordingly, without the mating adhesive surface areas being increased, 
the bond strength of the IC card can be increased. 
Preferably, each of the first and second covers may also includes a 
peripheral wall formed therein along the perimeter of the associated cover 
so as to extend generally transverse to the associated flat panel. By so 
doing, the respective peripheral walls of the first and second covers can, 
when the first and second covers are mated together, define a reservoir 
inside the IC card for accommodating a portion of the adhesive material 
squeezing from a plane of joint between the first and second upright 
walls. This is particularly advantageous in that since that portion of the 
adhesive material is accommodated within the reservoir invisible from the 
outside of the IC card, such a step of removing flashes of the adhesive 
material hitherto required in the prior art IC card can be dispensed with. 
According to the present invention, the adhesive material filled in the 
chamber flows outwardly from the chamber over the first upright wall and 
is in turn supplied to the plane of joint between the first and second 
upright walls to thereby form a bond layer. Therefore, portion of the 
adhesive material squeezing from the surface areas to be bonded together 
can be accommodated within the reservoir without being flowing outwardly 
from the IC card and, therefore, no extra step of applying the adhesive is 
also needed, making it possible to simplify the process of making the IC 
card. 
It may be possible that when an external stress may act on the IC card from 
the second cover, the circuit module accommodated within the IC card may 
be damaged. To avoid this possibility, the IC card may include an elastic 
cushioning element interposed between the adhesive layer, formed by curing 
the adhesive material filled in the chamber, and a portion of the second 
flat panel immediately above the adhesive layer so that the external 
stress applied to the IC card can be lessened to thereby protect the 
circuit module. 
Instead of the use of the elastic cushioning element, a cushioning air 
layer may be employed. This air layer can readily be formed by designing 
the first upright wall to have a free end terminating at a position spaced 
a distance inwardly from the second flat panel to allow the cushioning air 
layer to be formed between the second flat panel and the bond layer in the 
chamber when the first and second covers are mated together. 
The present invention also provides a method of making an IC card of the 
type comprising a first cover including a first flat panel and a first 
upright wall formed therein adjacent a perimeter of the flat panel so as 
to extend transverse to the flat panel and having a joint surface area, 
the first upright wall defining a chamber in cooperation with a portion of 
the first flat panel; and a second cover including a second flat panel and 
a second upright wall formed therein adjacent a perimeter of the flat 
panel so as to extend transverse to the flat panel and having a joint 
surface area. According to this method, a circuit module is first disposed 
within the chamber in the first cover, followed by filling an adhesive 
material within the chamber in a quantity sufficient to allow a top 
surface of the filled adhesive material to raise slightly above a plane 
flush with a free end face of the first upright wall. Then, the second 
cover is mounted on the first cover with the first upright wall 
encompassing the second upright wall, and the both are subsequently 
pressed together to allow a portion of the adhesive material within the 
chamber to squeeze outwardly from the chamber into a gap between the first 
and second upright walls so as to bond the first and second upright walls 
together. 
With the IC card making method of the present invention, filling of the 
adhesive material within the chamber defined in the first cover and 
subsequent capping of the second cover over the first cover allows the 
adhesive material to be supplied to surface areas to be bonded together, 
no extra step of applying the adhesive material to the surface areas to be 
bonded together is needed, and therefore, no extra step of applying the 
adhesive material to the joint surface area is needed, making it possible 
to simplify the process of making the IC card. 
Preferably, each of the first and second covers also includes a peripheral 
wall formed therein along the perimeter of the associated cover so as to 
extend generally transverse to the associated flat panel, such that the 
respective peripheral walls of the first and second covers, when the first 
and second covers are mated together, define a reservoir inside the IC 
card for accommodating portion of the adhesive material squeezing from a 
plane of joint between the first and second upright walls. In such case, 
when the first and second covers are mated together, that portion of the 
adhesive material can advantageously flow into the reservoir. 
Because of this, no extra step of removing possible flashes is also needed, 
making it possible to simplify the process of making the IC card.

DETAILED DESCRIPTION OF THE EMBODIMENT 
Referring first to FIGS. 1 and 2F, a non-contact IC card comprises, as is 
the case with the prior art IC card shown in and described with reference 
to FIG. 6, generally rectangular first and second covers 10 and 20 made of 
thermoplastic resin and having a substantially equal size. The first and 
second covers 10 and 20 are so configured and so designed that, when mated 
and boded together, they define a generally flattened closed box. Each of 
the first and second covers 10 and 20 comprises a flat panel 10a or 20a 
and a generally rectangular peripheral wall 10b or 20b formed integrally 
with the flat panel 10a or 20a so as to protrude from a perimeter of the 
flat panel 10a or 20b in a direction generally transverse thereto. 
The flat panel 10a of the first cover 10 is formed integrally with a 
generally rectangular-sectioned tubular wall 11 which is positioned inside 
the peripheral wall 10b and which protrudes in a direction conforming to 
the direction of protrusion of the peripheral wall 10b, i.e., upwardly as 
viewed in FIG. 2F, and perpendicular to the flat panel 10a. Similarly, the 
flat panel 20a of the second cover 20 is formed integrally with a 
generally rectangular-sectioned tubular wall 21 which is positioned inside 
the peripheral wall 20b and which protrudes in a direction conforming to 
the direction of protrusion of the peripheral wall 20b, i.e., downwardly 
as viewed in FIG. 2F, and perpendicular to the flat panel 20a. 
As will become clear from the subsequent description, one of the tubular 
walls 11 and 21 is so undersized relative to the other of the tubular 
walls 11 and 21 so that one tubular wall can be capped onto the other 
tubular wall so as to enclose the latter. In the illustrated embodiment, 
the tubular wall 11 is undersized relative to the tubular wall 21 and, 
accordingly, when the first and second covers 10 and 21 are mated together 
to complete the IC card, the tubular wall 21 receives therein and 
encompasses the tubular wall 11. 
The IC card of the above described construction is assembled in the manner 
which will now be described with reference to FIGS. 2A to 2F. FIG. 2A 
illustrates a step of mounting electronic component parts 2 such as ICs 
(integrated circuits) and chip capacitors on a mother board to form a 
plurality of, for example, four, independent circuit modules 3 for the 
corresponding number of the IC cards. 
The mother board shown in FIG. 2A is subsequently broken, or divided in any 
suitable manner, into the four circuit modules 3 as shown in FIG. 2B. The 
use of the mother board makes it possible to reduce the tact time required 
in accomplishing mounting of the IC components. 
As shown in FIG. 2C, one of the four circuit modules 3 is then mounted in a 
chamber 15 defined in the first cover 10 by the tubular wall 11 in 
cooperation with the flat panel 10a. After the mounting of the circuit 
module 3, and as shown in FIG. 2D, a power source cell 4 is mounted inside 
the chamber 15 and soldered to associated terminals on the circuit module 
3, followed by mounting and soldering of an antenna coil 5 for selective 
transmission and receiving of data to and from an external system 
appliance. The antenna coil 5 is, according to the present invention, 
accommodated within a peripheral space 16 defined between the tubular wall 
11 and the peripheral wall 1Ob. As will become clear from the subsequent 
description, the peripheral space 16 concurrently serves as a sealed 
reservoir for a deposit of adhesive material. 
Thereafter, as shown in FIG. 2E, a adhesive material 6 of thermosetting 
resin, for example, epoxy resin, is filled in the chamber 15 by the use of 
any suitable dispenser. The amount of the adhesive material 6 to be filled 
in the chamber 15 is preferably so chosen that, when the adhesive material 
6 is completely filled in the chamber 15, the top surface of the filled 
adhesive material 6 can raise slightly above a plane flush with a free end 
face of the tubular wall 11 opposite to the flat panel 10b as clearly 
depicted in FIG. 2E, it being however to be noted that the amount of 
portion of the adhesive material that raises above the plane flush with 
the free end face of the tubular wall 11 should be smaller then the volume 
of the free space or reservoir 16. 
Finally, as shown in FIG. 2F, the second cover 20 is mounted on the first 
cover 10 with the tubular wall 21 receiving therein the tubular wall 11 
integral of the first cover 10. Thereafter, the assembly including the 
first and second covers 10 and 20 is placed in a constant temperature bath 
maintained at, for example, 70.degree. C. to cause the adhesive material 6 
to cure, thereby completing the IC card. 
The tubular wall 11 of the first cover 10 is so sized relative to the 
tubular wall 21 of the second cover 20 that an annular gap of about 0.1 mm 
can be formed between an inner peripheral surface of the tubular wall 21 
and an outer peripheral surface of the tubular wall 11. Accordingly, when 
the second cover 20 is mounted on the first cover 10 and is then pushed 
against the first cover 10 or the both are pressed together, that portion 
of the adhesive material 6 raising above the plane flash with the free end 
face of the tubular wall 11 is forced to flow into the annular gap between 
the mutually confronting outer and inner peripheral surfaces of the 
tubular walls 11 and 21 until it reaches a portion of the reservoir 16 
adjacent a free end face of the tubular wall 21 positioned outside the 
tubular wall 11 of the first cover 10. Placement of the assembly within 
the constant temperature bath results in curing of not only a major 
portion of the adhesive material 6 filled within the chamber 15, but also 
that portion of the adhesive material 6 which has flowed into the annular 
gap between the mutually confronting outer and inner peripheral surfaces 
of the tubular walls 11 and 21. 
Thus, according to the present invention, the adhesive material 6 used 
serves not only to bond the respective flat panels 10a and 20a of the 
first and second covers 10 and 20 together, but also to bond the mutually 
confronting outer and inner peripheral surfaces of the tubular walls 11 
and 21 together. Since the mutually confronting outer and inner peripheral 
surfaces lie in a direction conforming to the direction along which the 
first and second covers 10 and 20 are separated and perpendicular to any 
one of the respective flat panels 10a and 20a, the IC card embodying the 
present invention can exhibit a bond strength which is ten or more times 
that exhibited by the IC card wherein surfaces to be joined together by 
the use of a adhesive material lie substantially parallel to any one of 
the flat panels, even though the area of each of the surfaces to be joined 
remains the same. Accordingly, with the IC card embodying the present 
invention, the possibility of separation of one of the covers from the 
other of the covers, which would result in a malfunctioning of the IC 
card, can advantageously be minimized. 
Moreover, that portion of the adhesive material 6 which has reached and 
cured at the portion of the reservoir 16 adjacent the free end face of the 
tubular wall 21 is located inside the reservoir 16 and is invisible from 
the outside of the IC card. Thus, according to the present invention, no 
extra step of removing flashes of the adhesive material which are, 
according to the prior art IC card shown in FIG. 6, apt to be formed 
around the outer perimeter of the IC card, is needed during the 
manufacture of the IC card of the present invention. This makes it 
possible to simplify the manufacture of the IC card. 
It is to be noted that respective free end faces of the peripheral walls 
10b and 20b of the first and second covers 10 and 20, which are held in 
contact with each other when the second cover 20 is mounted onto the first 
cover 10 in the manner described above may or may not be bonded with each 
other, although in the illustrated embodiment they are not bonded 
together. Where the respective free end faces of the peripheral walls 10b 
and 20b are not bonded together such as shown, that portion of the 
adhesive material 6 which has flowed into the annular gap between the 
mutually confronting outer and inner peripheral surfaces of the tubular 
walls 11 and 21 is preferably accommodated within the reservoir 16 at a 
location adjacent the free end face of the tubular wall 21. For this 
reason, in consideration of the accuracy of filling of the adhesive 
material 6 into the chamber 15, the volume of a portion of the reservoir 
16 below the level flush with the free end face of the peripheral wall 10b 
is preferably so chosen as to be about 30% of the volume of the chamber 
15. 
In the foregoing embodiment of the present invention, the adhesive material 
6 has been shown and described as filled in the chamber 15. This is 
particularly advantageous in that both of the circuit module 3 and the 
electronic component parts 2 on the circuit module 3 can be firmly 
retained in position. 
However, the present invention does not necessarily preclude the 
possibility of only the free end faces of the tubular walls 11 and 21 
being bonded to the flat panels 20a and 10a, respectively. 
In addition, in the illustrated embodiment, the tubular walls 11 and 12 
have been shown and described as bonded in side-by-side fashion. In other 
words, each of the tubular walls 11 and 21 has such a length that when the 
first and second covers 10 and 20 are mated together the free end face of 
the tubular wall 11 and the free end face of the tubular wall 21 can 
terminate respectively within the second and first covers 20 and 10 to 
accomplish a so-called cap-and-cup joint. However, in the assembled 
condition of the IC card according to the present invention, the tubular 
walls 11 and 21 may be aligned in position with each other and, in such 
case, the extent to which each of the tubular walls 11 and 21 protrudes 
from the associated flat panel 10a or 20a towards the opposite flat panel 
20a or 10a should be so chosen as to form an inclined butt joint. The 
inclined butt joint refers to a joint in which the plane of the joint 
between the tubular walls 11 and 21 in the assembled condition of the IC 
card extend slantwise relative to the direction of protrusion of the 
tubular walls 11 and 21 from the associated flat panel 10a and 20a. 
Referring now to FIG. 3 showing a modified form of the IC card according to 
the present invention, a generally rectangular elastic sheet 31 such as, 
for example, a silicone rubber sheet, is interposed between the flat panel 
20a of the second cover 20 and the cured adhesive material 6 within the 
chamber 15. The interposition of the elastic sheet 31 serves as a 
cushioning element effective to protect the circuit module 3 from being 
damaged by the effect of external impacts or shocks. 
In another modified form of the IC card shown in FIG. 4, an air layer 32 is 
formed between the flat panel 20a of the second cover 20 and the cured 
adhesive material 6 within the chamber 15. This air layer 32 can readily 
be formed by choosing the extent of protrusion of the tubular wall 11 to 
such a value that, when the first and second covers 10 and 20 are mated 
together, the free end face of the tubular wall 11 may terminate at a 
position spaced a distance inwardly from the flat panel 20a of the second 
cover 20. 
The air layer 32 shown in FIG. 4 serves the same purpose as that 
accomplished by the use of the elastic sheet 31 shown in FIG. 31. 
FIG. 5 illustrates a cross-section, taken along the line V--V in FIG. 1, of 
one corner area of the IC card where a chain hole 30 is formed. This chain 
hole 30 is used for attachment of the IC card to a key holder by means of 
a connecting element such as, for example, a chain, thread or ring. As 
shown in FIG. 5, one corner area of the first cover 10 is formed with an 
annular recess 12 extending inwardly of the first cover 10 and, on the 
other hand, a corresponding corner area of the second cover 20 is formed 
with a annular projection 22 of a size sufficient to be press-fitted into 
the round recess 12. Thus, it will readily be understood that when the 
first and second covers 10 and 20 are mated together in the manner 
described hereinbefore, respective hollows in the annular recess and 
projection 12 and 22 are coaxially aligned with each other to define the 
chain hole 30. 
The use of the annular projection 22 in the second cover 20 that is adapted 
to be press-fitted into the annular recess 12 in the first cover 10 is, 
regardless of the presence or absence of the chain hole 30, particularly 
advantageous in that any possible separation of the second cover 20 from 
the first cover 10 which would otherwise take place before the filled 
adhesive material 6 is completely cured can be eliminated. 
From the foregoing description, it has now become clear that the first and 
second covers are mated together with the respective tubular walls bonded 
together in either a cap-and-cup fashion or an inclined butt fashion and, 
accordingly, a bond component acting in the shearing direction relative to 
the plane of joint enhances the bond strength of the plane of joint. 
Accordingly, as compared with the case in which the plane of joint does 
not incline such as in the prior art IC card, for a given adhesive area, 
the bond strength can be increased. In particular, if the plane of joint 
lies perpendicular to any one of the respective flat panels of the first 
and second covers, the bond strength can attain a value about ten times 
that exhibited by the prior art IC card, making it possible to minimize 
the possible occurrence of trouble in the IC card. 
It is also clear that since according to the present invention filling of 
the adhesive material within the chamber defined in the first cover and 
subsequent capping of the second cover over the first cover allows the 
adhesive material to be supplied to surface areas to be bonded together, 
no extra step of applying a adhesive material to the surface areas to be 
bonded together is needed. Moreover, portion of the adhesive material 
squeezing from the surface areas to be bonded together can be accommodated 
within the reservoir without being flowing outwardly from the IC card and, 
therefore, no extra step of removing possible flashes is also needed, 
making it possible to simplify the process of making the IC card. 
Although the present invention has been described in connection with the 
preferred embodiments thereof with reference to the accompanying drawings, 
it is to be noted that various changes and modifications are apparent to 
those skilled in the art. Such changes and modifications are to be 
understood as included within the scope of the present invention as 
defined by the appended claims, unless they depart therefrom.