Method of making smart cards

• US 5,955,021 A
• Filed: 09/08/1997
• Issued: 09/21/1999
• Est. Priority Date: 05/19/1997
• Status: Expired due to Term

• Current Assignee: Cardxx Incorporated
• Original Assignee: Cardxx Incorporated
• Inventors: Tiffany, Harry J. III
• Primary Examiner(s): RAIMUND, CHRISTOPHER W
• Application Number:
  US08/925,593
• Time in Patent Office: 743 Days
• Field of Search: 264/272.11, 264/272.13, 264/272.15, 264/272.17
• US Class Current: 264/272.11
• CPC Class Codes: B29C 2045/14532 injecting between two sheets
• CPC Class Codes: B29C 2045/2714 elongated, e.g. film-like, annular
• CPC Class Codes: B29C 45/14647 Making flat card-like articles with an incorporated IC or chip module, e.g. IC or chip cards
• CPC Class Codes: B29C 70/685 by laminating inserts between two plastic films or plates
• CPC Class Codes: G06K 19/07745 Mounting details of integrated circuit chips
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

Smart cards having high quality external surfaces can be made through use of partially cured, low shrinkage glues to hold the smart card'"'"'s electronic elements during their immersion in a thermosetting material that becomes the core layer of said cards.

Claims

1. A process for making a smart card comprising a top layer, a core layer in which an electronic component is embedded and a bottom layer, said process comprising:

(1) using at least one mound of low shrinkage glue to connect an electronic component to an inside surface of the bottom layer of the smart card and thereby form a bottom layer/low shrinkage glue/electronic component assembly;

(2) partially curing the mound of low shrinkage glue to produce a bottom layer/partially cured glue/electronic component assembly;

(3) positioning the bottom layer/partially cured glue/electronic component assembly in a bottom mold;

(4) positioning a top layer in a top mold;

(5) closing the top mold to the bottom mold in a manner that creates a void space between the top layer and bottom layer;

(6) injecting a thermosetting polymeric material into the void space at temperature and pressure conditions which are such that;

(a) the electronic component is held in place by the mound of partially cured glue while the electronic component and mound of partially cured glue are immersed in the thermosetting material, (b) at least one layer of the smart card is at least partially cold, low pressure molded into a cavity in the top mold, (c) gases and excess polymeric material are driven out of the void space, (d) the electronic component is encapsulated in the thermosetting polymeric material before the partially cured glue becomes completely cured and (e) the thermosetting polymeric material bonds with both the top layer and the bottom layer to produce a unified precursor smart card body;

(7) removing the unified precursor smart card body from the mold device; and

(8) trimming the precursor smart card to a desired dimension to produce a smart card.

2. The method of claim 1 wherein the electronic component does not come in physical contact with the bottom layer.

3. The method of claim 1 wherein the electronic component is positioned at least 0.01 mm above the bottom layer.

4. The method of claim 1 wherein the electronic component is an antenna that is pedestaled on at least two mounds of glue that hold the antenna at least 0.01 mm above the bottom layer.

5. The method of claim 1 wherein the low shrinkage glue is a cyanoacrylate adhesive type glue that is capable of at least partially curing in less than about 5 seconds.

6. The method of claim 1 wherein the low shrinkage glue is a UV curable glue that is capable of at least partially curing in less than about 5 seconds.

7. The method of claim 1 wherein the low shrinkage glue is at least 10 percent cured in less than about 3 seconds.

8. The method of claim 1 wherein the low shrinkage glue is about 10 to about 90 percent cured while it is immersed in the thermosetting material.

9. The method of claim 1 wherein the inside surface of the top layer and the inside surface of the bottom layer are treated to facilitate the creation of a strong bond between the top layer and the thermosetting material and the bottom layer and the thermosetting material.

10. The method of claim 1 wherein the inside surface of the top layer and the inside surface of the bottom layer are treated by coating each with a bonding agent.

11. The method of claim 1 wherein the inside surface of the top layer and the inside surface of the bottom layer are treated by a corona discharge process.

12. The method of claim 1 wherein the thermosetting material is injected into the void space at a pressure between about ambient pressure and about 500 psi.

13. The method of claim 1 wherein the thermosetting material is injected into the void space at a pressure between about 80 and about 120 psi.

14. The method of claim 1 wherein the thermosetting material is injected into the void space at a temperature between about 56°

F. and about 100°

F.

15. The method of claim 1 wherein the thermosetting material is injected into the void space between the top layer and the bottom layer at a temperature between about 65°

F. and about 70°

F.

16. The method of claim 1 wherein a film bearing alphanumeric/graphic information is applied to the inside surface of the top layer.

17. The method of claim 1 wherein a layer of opacity preventing material is applied to the inside surface of the top layer and the inside surface of the bottom layer.

18. The method of claim 1 wherein the electronic component is an antenna that is electrically connected to a chip.

19. The method of claim 1 wherein the top layer and the bottom layer are each formed from a flat sheet of polymeric material.

20. The method of claim 1 wherein the top layer is preformed with at least one card-forming cavity.

21. The method of claim 1 wherein the top layer is molded into a card-forming cavity of a top mold and the bottom layer is molded against a substantially flat surface of a bottom mold.

22. The method of claim 1 wherein the thermosetting material is a polyurethane.

23. The method of claim 1 wherein the thermosetting material is an epoxy.

24. The method of claim 1 wherein the thermosetting material is a unsaturated polyester.

25. The method of claim 1 wherein the void space is filled by a gate whose width is at least about 25 percent of the width of an edge of a precursor card being serviced by said gate.

26. A process for making a smart card comprising a top layer, a core layer in which an electronic component is embedded and a bottom layer, said process comprising:

(1) using at least one mound of low shrinkage glue having a volume of less than bout 0.1 cc to position an electronic component from about 0.075 to about 0.13 mm from an inside surface of the bottom layer of the smart card and thereby form a bottom layer/low shrinkage glue/electronic component assembly;

(2) curing the mound of low shrinkage glue from about 10 percent to about 90 percent of the total curing the glue will experience in a period of time less than about 5 seconds to produce a bottom layer/partially cured glue/electronic component assembly;

(3) positioning the bottom layer/partially cured glue/electronic component assembly in a bottom mold;

(4) positioning a top layer in a top mold;

(5) closing the top mold to the bottom mold in a manner that creates a void space between the top layer and bottom layer;

(6) injecting a thermosetting material into the void space at a temperature between about 65°

F. and about 70°

F. and at a pressure between about 80 psi and about 120 psi which are such that;

(a) the electronic component is held in place by the mound of partially cured glue while the electronic component and mound of partially cured glue are immersed in the thermosetting material, (b) at least one layer of the smart card is at least partially cold, low pressure molded into a cavity in the top mold, (c) gases and excess polymeric material are driven out of the void space, (d) the electronic component is encapsulated in the thermosetting polymeric material before the partially cured glue becomes completely cured and (e) the thermosetting polymeric material bonds with both the top layer and the bottom layer to produce a unified precursor smart card body;

(7) removing the unified precursor smart card body from the mold device; and

(8) trimming the precursor smart card to a desired dimension to produce a smart card.