IC card

Abstract: An IC card (21) includes a substrate (13), semiconductor devices (1a-1h) mounted on at least one of majors surfaces of the substrate, and a casing in which the substrate with the semiconductor devices mounted on it is housed. The casing includes a frame (5) and panels (7, 8) bonded to the frame on the opposite sides of the frame by means of adhesive layers (9a, 9b). Means for preventing the semiconductor devices from being bonded to the panel via the adhesive layers are disposed at locations on the adhesive layers facing the semiconductor devices.

Description: This invention relates to an IC card, which comprises a substrate with semiconductor devices, such as IC's, mounted on it, a frame within which the substrate with the IC's is mounted, and panels bonded to the frame on its opposite sides to form a casing for housing the IC's. BACKGROUND OF THE INVENTION A conventional IC card of the above-described type is now described in detail with reference to Figures 1, 2 and 3. Figure 1 is a cross-sectional view of a conventional IC card 20, Figure 2 is a perspective view of the conventional IC card inserted into an inlet port of an external device, and Figure 3 is a cross-sectional view of the IC card of Figure 1 when it is bent. On opposing major surfaces of a substrate 13, lands 3a, 3b, ..., 3j are disposed. Each of the lands constitutes a part of the circuit of the IC card 20. Leads 2a, 2b, ..., 2h of IC's 1a, 1b, ..., 1h, which may be semiconductor devices for storing or processing information, are connected to the associated lands 3a, 3b, ..., 3j by means of solder layers 4a, 4b, ..., 4j. Thus, the IC's 1a, 1b, 1c, 1d, 1e, 1f, 1g and 1h are electrically and mechanically coupled to the respective associated ones of the opposing major surfaces of the substrate 13 by the leads 2a, 2b, 2c, 2d, 2e, 2f, 2g, and 2h soldered to the associated lands 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i and 3h by means of the solder layers 4a, 4b, 4c, 4d, 4e, 4f, 4g, 4h, 4i and 4j. The substrate 13 on which the IC's 1a, 1b, ..., 1h are mounted is disposed in a frame 5. A connector 6 is disposed at one end of the frame 5 for connecting the IC card 20 to an external device which is described later. The connector 6 is connected to the substrate 13 within the frame 5. A top panel 7 and a bottom panel 8 are bonded with respective adhesive layers 9a and 9b to the peripheral edges of the frame 5 on the opposite sides of the frame 5 to thereby form a casing, in which the substrate 13 with the IC's 1a-1h mounted thereon is housed. The IC's 1a, 1b, ... 1h are bonded to the panels 7 and 8 with the adhesive layers 9a and 9b, respectively. The IC card 20 is inserted, by a user, into an external device 10 through an inlet port 10a thereof, as shown in Figure 2. The insertion of the IC card 20 into the external device 10 causes the connector 6 of the IC card 20 to be connected to a connector (not shown) within the external device 10. When necessary processing has been completed, the IC card 20 is pulled out of the external device 10. If the IC card 20 is roughly handled and receives abnormal force when, for example, it is inserted into or withdrawn from the external device 10, the IC card 20, particularly its rear part opposite to the end where the connector 6 is disposed, is bent in the direction perpendicular to the major surfaces of the card, as shown in Figure 3. When the IC card 20 is bent in the clockwise direction as in the case shown in Figure 3, not only the IC card 20 itself is deformed, but also the IC's 1a-1d, which are bonded to the top panel 7 via the adhesive layer 9a, are forced to move rearward due to the bending of the top panel 7. As for the IC's 1e-1h, which are bonded to the bottom panel 8 via the adhesive layer 9b, are forced to move forward toward the connector 6 of the IC card 20 due to the bending of the panel 8. When the IC's 1a-1d on the top surface of the substrate 13 move rearward and the IC's 1e-1h on the opposite surface of the substrate 13 move forward, force is exerted via the leads 2a-2h of the respective IC's to the associated solder layers 4a-4j. Since the amount of displacement of the rearmost IC's 1a and 1e is largest, the leads 2a and 2e of the IC's 1a and 1e are deformed more than the other leads. Accordingly, if the IC card 20 is repeatedly bent as it is inserted into the external device 10, the solder layers connected to the leads of the IC's, particularly the solder layers 4a, 4b, 4f and 4g to which the leads 2a and 2e of the IC's 1a and 1b located in the rear portion of the IC card 20 are connected, may be cracked, which may cause disconnection of the leads 2a and 2e from the associated lands 3a,3b,3f and 3g, or, sometimes the leads 2a and 2b may snap. An object of the present invention is to provide an improved IC card, in which at least those IC's which are located in the rear portion of the card are not bonded to the adhesive layers so that the IC's may not be forced to move forward or rearward by the bending of the top and bottom panels which occurs when the IC card is bent as shown in Figure 3, for example, whereby no stress is applied to the leads or the solder layers. A similar problem is addressed in DE-A-3626604. In the arrangement shown in this disclosure an integrated circuit is attached to an edge of the substrate rather than being mounted on one of its major surfaces. The casing of the card is then recessed to provide a cavity for the IC which is bigger than the IC itself. EP-A-0268830 discloses a card having a single electronic component embedded therein, housed in a recess in a substrate layer. The substrate is adhered to the card material via an adhesive layer but an extra layer of deformable material is provided in the region of the electronic component to prevent the component from adhering to the adhesive layer. The resulting arrangement is still liable to be damaged when bent because the electronic component is rigidly connected to the substrate. In comparison with the IC card of the prior art shown in Figures 1 and 3, the IC card of the present invention has at least one of the semiconductor devices (1a-1h) being adhered to one of said adhesive layers (9a,9b) and is characterised in that at least one of the remaining semiconductor devices (1a-1h) is prevented from adhering to said adhesive layers (9a,9b) by adhesion preventing means disposed between the panels and the semiconductor devices whereby forces bending said IC card are not transmitted to the semiconductor device(s) (1a-1h) adjacent to said adhesion preventing means. Certain embodiments of the invention will now be described by way of example only and with reference to the accompanying drawings. In the drawings: Figure 1 is a cross-sectional view of a conventional IC card; Figure 2 is a perspective view of the IC card of Figure 1 inserted into an external device; Figure 3 is a cross-sectional view of the IC card of Figure 1 when it is bent; Figure 4 is a cross-sectional view of an IC card according to a first embodiment of the present invention, in which adhesion preventing sheets are disposed between IC's and adhesive layers; Figure 5 is a reduced cross-sectional view along V-V in Figure 4; Figure 6 is a cross-sectional view of the IC card of Figure 4 when it is bent; Figure 7 is a cross-sectional view of an IC card according to a second embodiment of the present invention; Figure 8 is a reduced, cross-sectional view along VIII-VIII in Figure 7; and Figure 9 is a cross-sectional view of the IC card of Figure 8 when it is bent. A first embodiment of the present invention is shown in Figures 4-6. The structure of an IC card 21 shown in Figures 4-6 is similar to that of the conventional IC card shown in Figure 1, except that adhesion preventing sheets 11a and 11b are disposed between an IC 1a and an adhesive layer 9a and between an IC 1e and an adhesive layer 9b, respectively. Thus, the IC's 1a and 1e are prevented from being bonded to the adhesive layers. Specifically, on the opposite major surfaces of the substrate 13, there are disposed lands 3a-3j which constitute part of the IC card circuit Semiconductor devices, such as IC's 1a-1h, for storing or processing information, are mounted with their leads 2a-2h bonded to the associated lands 3a-3j by means of solder layers 4a-4j. Thus, the respective IC's are electrically and mechanically coupled to the major surfaces of the substrate 13. The substrate 13 with the IC's 1a-1h mounted thereon is disposed within a casing which comprises a frame 5 and top and bottom panels 7 and 8 which are bonded to the opposite sides of the frame 5 by means of respective adhesive layers 9a and 9b. As shown in Figure 5, at one end of the frame 5, a connector 6 is disposed, which is used for connecting the IC card to an external device such as the device 10 shown in Figure 2. The connector 6 is connected to the substrate 13 within the casing. As stated previously, the IC card 21 according to the first embodiment of the present invention employs the adhesion preventing sheets 11a and 11b disposed between the IC's 1a and 1e and the adhesive layers 9a and 9b, respectively, so that the IC's 1a and 1e which are located in the rear portion of the IC card 21 do not adhere to the adhesive layers 9a and 9b. The adhesive layers 9a and 9b are first disposed on the top and bottom panels 7 and 8, respectively, and, then, the adhesion preventing sheets 11a and 11b are disposed to adhere to the adhesive layers 9a and 9b at the locations facing the IC's 1a and 1b. The IC card 21 with the above-described structure is inserted into or withdrawn from the external device 10, shown in Figure 2, through the inlet port 10a when a user uses the IC card 21. When the IC card 21 is inserted into or withdrawn from the device 10, it may be bent as shown in Figure 6. Since the adhesion preventing sheets 11a and 11b prevent the IC's 1a and 1e from being bonded to the panels 7 and 8, it never occurs that the bending of the panels 7 and 8 would push the IC's 1a and 1e to move forward or rearward. Accordingly, no undesired stress is applied to any of the leads 2a and 2e or to any of the solder layers 4a, 4b, 4f and 4g. Thus, no fault, such as defective connection due to cracking of the solder layers and disconnection of the leads 2a and 2e, will occur. In this first embodiment, adhesion preventing sheets are disposed only at those locations of the adhesive layers 9a and 9b which face the IC's 1a and 1e which would otherwise be displaced greatly when the IC card 21 is bent as shown in Figure 6. However, such adhesion preventing sheets may be disposed for almost all of the IC's 1a-1h. Thus, not only when the IC card is bent, as shown in Figure 6, as it is inserted into or withdrawn from the external device 10, but also when the IC card is largely bent at any location on the IC card, no stress will be applied to the IC's, the leads, or the solder layers and, therefore, no fault, such as defective connection due to craking of the solder layers and disconnection of the leads, will occur. IC's may be disposed only on one surface of the substrate 13. Figures 7, 8 and 9 show an IC card 22 according to a second embodiment of the present invention. In Figures 7, 8 and 9, the similar or equivalent portions to those shown in Figures 4, 5 and 6 are designated by the same reference numerals, and their details are not described. In the second embodiment, in order to prevent the IC's 1a and 1c from being bonded to the associated panels 7 and 8 via the adhesive layers 9a and 9b, openings 23a and 23b are formed in the adhesive layers 9a and 9b at those locations which face the IC's 1a and 1e. The openings 23a and 23b may be formed by removing the portions of the adhesive layers 9a and 9b before they are applied to the panels. As in the IC card 21 of the first embodiment, even when the IC card 22 is bent, as shown in Figure 9, as it is inserted into or withdrawn from the external device 10 shown in Figure 2, the IC's 1a and 1e will not be forced to move forward or rearward by the panels 7 and 8, since they are separated from the panels 7 and 8 by the openings 23a and 23b. Accordingly, any stress is applied neither to the leads 2a and 2e of the IC's 1a and 1e nor to the solder layers 4a, 4b, 4f and 4g which connect the leads to the lands. Therefore, faults, such as defective connection due to cracking of the solder layers and disconnection of the leads can be effectively avoided. In the second embodiment, too, as in the first embodiment, openings like the ones 23a and 23b may be formed in the adhesive layers 9a and 9b for almost all of the IC's 1a-1h. Then, neither deformation of the IC card 22 when it is bent as shown in Figure 9, as it is inserted into or withdrawn from the external device 10 shown in Figure 2, nor other type of deformation which could occur during the handling of the IC card 22 causes any stress to be applied to the IC's, the leads or the solder layers. In this second embodiment, too, IC's may be disposed only on one of the two major surfaces of the substrate 13. In the described embodiments, the adhesive layers 9a and 9b are sued, but adhesive sheets may be used in place of the adhesive layers. As described in detail above, according to the present invention, at least those IC's which are located in the rear part of an IC card are prevented from adhering to panels of the card via adhesive layers. Accordingly, even if the panels or a frame are more or less deformed during the use or handling of the card, none of the IC's, the leads and the solder layers connecting the leads to the substrate within the casing of the IC card are stressed and, therefore, faults, such as disconnection of the leads and cracking of the solder layers, are avoided. Thus, according to the present invention, highly reliable, high quality IC cards can be produced.

Claims: An IC card comprising a substrate (13) having two opposing major surfaces, a plurality of semiconductor devices (1a-1h) mounted by means of lead conductors (2a-2h) thereof on at least one of said two major surfaces of said substrate, and a casing (5,7,8) housing said substrate with said semiconductor devices (1a-1h) mounted thereon, said casing comprising a frame (5) having opposed sides, opposed front and rear ends, an electrical connector (6) disposed at the front end, two panels (7,8) each panel having an inside surface and an outside surface, and an adhesive layer (9a,9b) disposed over the inside surface of each of said panels, each of the adhesive layers bonding one of said panels to respective opposite sides of said frame (5); the substrate (13) on which said semiconductor devices are mounted being disposed within said casing substantially equidistant from said panels (7,8) at least one of the semiconductor devices (1a-1h) being adhered to one of said adhesive layers (9a,9b) characterised in that at least one of the remaining semiconductor devices (1a-1h) is prevented from adhering to said adhesive layers (9a,9b) by adhesion preventing means disposed between the panels and the semiconductor devices whereby forces bending said IC card are not transmitted to the semiconductor device(s) (1a-1h) adjacent to said adhesion preventing means. An IC card according to Claim 1 wherein said adhesion preventing means comprises adhesion preventing sheets (11a,11b) which are disposed in contact with some of said semiconductor devices (1a-1h) and are bonded to said adhesive layers (9a,9b) at locations facing said semiconductor devices (1a-1h) so that said semiconductor devices are prevented from adhering to said adhesive layers (9a,9b). An IC card according to Claim 1 wherein said adhesion preventing means comprises openings (23a, 23b) formed in said adhesive layers at locations facing some of said semiconductor devices (1a-1h) so that said semiconductor devices are prevented from adhering to said adhesive layers. An IC card according to Claim 1, 2 or 3 wherein said semiconductor devices are mounted on both of the major surfaces of said substrate. An IC card according to any preceding claim including adhesion preventing means for preventing only those semiconductor devices (1a-1h) mounted proximate the rear end of the frame (5) from adhering to said adhesive layers.

Inventors: MAEDA HAJIME, OMORI MAKOTO, ONBUCHI JUN, ONODA SHIGEO, TACHIKAWA TORU, UENAKA TAKESHI, MAEDA, HAJIME, OMORI, MAKOTO, ONBUCHI, JUN, ONODA, SHIGEO, TACHIKAWA, TORU, UENAKA, TAKESHI
Applicants: MITSUBISHI ELECTRIC CORP, MITSUBISHI DENKI KABUSHIKI KAISHA
Application year: 1990
Main classification: H01L23
IPC codes: H01L23, H01L25, G06K19, H05K3