Transponder and injection-molded part and method for manufacturing same

• US 20030076662A1
• Filed: 11/25/2002
• Published: 04/24/2003
• Est. Priority Date: 05/14/1999
• Status: Abandoned Application

• Current Assignee: Sokymat SA (Assa Abloy AB)
• Original Assignee: Sokymat SA (Assa Abloy AB)
• Inventors: Miehling, Martin
• Application Number:
  US10/302,967
• Publication Number:
  US 20030076662A1
• Time in Patent Office: Days
• US Class Current: 361/760
• CPC Class Codes: B29C 2045/14131 using positioning or centering means forming part of the insert
• CPC Class Codes: B29C 2045/14852 incorporating articles with a data carrier, e.g. chips
• CPC Class Codes: B29C 39/10 incorporating preformed parts or layers, e.g. casting around inserts or for coating articles coating a surface by casting in general B05D1/30, B29C39/126 takes precedence
• CPC Class Codes: B29C 39/123 Making multilayered articles
• CPC Class Codes: B29C 45/14073 using means being retractable during injection
• CPC Class Codes: B29C 45/14639 for obtaining an insulating effect, e.g. for electrical components
• CPC Class Codes: B29C 45/1671 with an insert
• CPC Class Codes: B29K 2105/0097 Glues or adhesives, e.g. hot melts or thermofusible adhesives
• CPC Class Codes: G06K 19/04 characterised by the shape
• CPC Class Codes: G06K 19/047 the record carrier being shaped as a coin or a gambling token
• CPC Class Codes: G06K 19/07724 the record carrier being at least partially made by a molding process molding in general B29C45/14
• CPC Class Codes: G06K 19/07745 Mounting details of integrated circuit chips
• CPC Class Codes: G06K 19/07749 the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
• CPC Class Codes: G06K 19/07779 the inductive antenna being a coil
• CPC Class Codes: G06K 19/07781 the coil being fabricated in a winding process
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2924/00011 Not relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01005 Boron [B]
• CPC Class Codes: H01L 2924/0102 : Calcium [Ca]
• CPC Class Codes: H01L 2924/01068 : Erbium [Er]
• CPC Class Codes: H01L 2924/181 : Encapsulation

Abstract

A transponder contains an integrated circuit, a power transmitting component (antenna) and a capsule made of a thermoplastic resin (hot glue) that surrounds the circuit continuously at least on one surface of the circuit. The glue preferably is a polyamide and surrounds the circuit protectively, ensuring a mechanical connection between the circuit and the antenna. The encapsulation with the hot glue is conducted at pressures and temperatures that are below the pressures and temperatures encountered during conventional injection molding. The transponder can be integrated into an injection molded part, for example a coin, by being placed in an injection mold in which it is supported by feet and then surrounded by molding material in a conventional injection molding process so that it develops a more resistant sheath.

Claims

1. An electrical circuit comprising an integrated circuit, an antenna and one or more electrical connections between the integrated circuit and the antenna, wherein at least the integrated circuit and the antenna are encapsulated within a capsule, and wherein the capsule comprises a thermoplastic resin having a melting point of from 120°

C. to 250°

C.

2. The electrical circuit according to claim 1, wherein the capsule completely encapsulates the electrical circuit.

3. The electrical circuit according to claim 1, wherein the capsule encapsulates the electrical circuit only on one surface of the electrical circuit.

4. The electrical connection according to claim 1, wherein the electrical circuit is encapsulated within the capsule such that at least one or more electrical connections are encapsulated by the thermoplastic resin.

5. The electrical connection according to claim 1, wherein the antenna is a coil.

6. Transponder comprising an electrical circuit containing at least one component suitable for interaction with an electromagnetic field encapsulated within a capsule, wherein the capsule comprises a thermoplastic resin having a melting point of from 120°

C. to 250°

C., and wherein the-electrical circuit is encapsulated by the thermoplastic resin such that at least an integrated circuit and an antenna of the electrical circuit are encapsulated by the thermoplastic resin.

7. Transponder according to claim 6, wherein the thermoplastic resin consists essentially of thermoplastic polyamide.

8. Transponder according to claim 6, wherein at least part of a surface of the capsule is covered with a cover layer of laminated film.

9. Transponder according to claim 8, wherein the laminated film comprises a plastic.

10. Transponder according to claim 9, wherein the plastic is polyvinyl chloride.

11. Transponder according to claim 6, wherein the antenna is a coil.

12. Transponder according to claim 6, wherein the electrical circuit further comprises one or more electrical connections connecting the integrated circuit in electrically conducting fashion with the antenna.

13. Transponder according to claim 6, wherein the capsule further comprises at least one supporting element projecting from its surface.

14. Transponder according to claim 6, wherein the capsule includes a material used as a mold during encapsulation with the thermoplastic resin.

15. Transponder according to claim 6, wherein the transponder further comprises a sheath of injection molded resin surrounding the encapsulated electrical circuit.

16. Method of manufacturing a transponder comprising an electrical circuit containing at least one component suitable for interaction with an electromagnetic field encapsulated within a capsule, wherein the capsule comprises a thermoplastic resin having a melting point of from 120°

C. to 250°

C., and wherein the electrical circuit is encapsulated by the thermoplastic resin within the capsule such that at least an integrated circuit and an antenna of the electrical circuit are encapsulated by the thermoplastic resin, comprising

placing at least one of the electrical circuits in a cavity of a mold, and

feeding the thermoplastic resin in molten form into the cavity to encapsulate the at least one electrical circuit and form the capsule, wherein the feeding is conducted at a temperature of from 120°

C. to 260°

C. and at a pressure of from 5 to 40 bars.

17. Method according to claim 16, wherein the placing places a supporting surface of the electrical circuit against the mold, and wherein the feeding consists of forming a partially covered electrical circuit covered with thermoplastic resin at least on one surface.

18. Method according to claim 16, wherein the placing places a supporting surface of the electrical circuit against the mold, wherein the feeding forms a partially covered electrical circuit covered with thermoplastic resin at least on one surface, and the method further comprises placing the partially covered electrical circuit in a cavity of a second mold such that the supporting surface is exposed to the cavity of the second mold, and filling the cavity of the second mold with the thermoplastic resin to form a fully covered electrical circuit.

19. Method according to claim 16, wherein the placing includes a plurality of pins supporting the electrical circuit within the cavity of the mold.

20. Method according to claim 19, wherein the method further comprises, following the feeding, removing the plurality of pins and subsequently filling the cavity of the mold once more with the thermoplastic resin.

21. Method according to claim 16, wherein the at least one electrical circuit comprises a plurality of electrical circuits that are encapsulated together so as to be held together by the thermoplastic resin.

22. Method according to claim 21, wherein the encapsulation forms a plate in which the plurality of electrical circuits are embedded, and the method further comprises stamping the transponder comprising at least one electrical circuit from the plate.

23. Method according to claim 22, wherein the method further comprises forming a film cover layer on one or both sides of the plate before the transponder is stamped from the plate.

24. Method according to claim 16, wherein the feeding is conducted at a temperature of at most 230°

C. and at a pressure of at most 35 bars.

25. Method according to claim 16, wherein the mold remains with the electrical circuit and forms at least a part of the capsule.

26. Method according to claim 16, wherein the method further comprises placing the transponder encapsulated in the thermoplastic resin in a cavity of an injection mold and subsequently injecting injection molding material into the cavity to form an injection molded part.

27. Method according to claim 26, wherein the injecting is conducted at a temperature of from 180°

C. to 400°

C. and at a pressure of from 50 bars to 2,000 bars.

28. Injection molded part with transponder integrated therein made according to the method of claim 26.