Method for manufacturing low cost electroluminescent (EL) illuminated membrane switches

• US 7,255,622 B2
• Filed: 06/27/2003
• Issued: 08/14/2007
• Est. Priority Date: 08/30/2001
• Status: Expired due to Fees

• Current Assignee: Novatech Electro-Luminescent Incorporated
• Original Assignee: Novatech Electro-Luminescent Incorporated
• Inventors: Lau, James, Stevenson, William C.
• Primary Examiner(s): Williams; Joseph L.
• Application Number:
  US10/608,370
• Publication Number:
  US 20060026821A1
• Time in Patent Office: 1,509 Days
• Field of Search: 445/50, 445/51, 445 23- 25, 427/66, 313504-506, 296/22, 298/46, 298/47, 216/12, 216/13, 216/5, 438/5
• US Class Current: 445/24
• CPC Class Codes: H01H 13/83 characterised by legends, e.g. Braille, liquid crystal displays, light emitting or optical elements
• CPC Class Codes: H01H 2219/018 Electroluminescent panel
• CPC Class Codes: H01H 2219/037 using organic materials, e.g. organic LED
• CPC Class Codes: H01H 2229/004 Conductive ink
• CPC Class Codes: H01H 2229/016 Selective etching
• CPC Class Codes: H01H 2229/02 Laser
• CPC Class Codes: H01H 2229/038 Folding of flexible printed circuit
• CPC Class Codes: H01H 2239/01 combined with other elements on the same substrate
• CPC Class Codes: Y10T 29/49105 Switch making
• CPC Class Codes: Y10T 29/49155 Manufacturing circuit on or in base
• CPC Class Codes: Y10T 29/49156 with selective destruction of conductive paths

Abstract

A method for manufacturing low cost electroluminescent (EL) illuminated membrane switches is disclosed. The method includes the steps of die cutting, embossing or chemically etching the metal foil surface of a metal foil bonded, light transmitting flexible electrical insulation to simultaneously form one or more front capacitive electrodes, membrane switch contacts and electrical shunt, electrical distribution means and electrical terminations that together form a flexible printed circuit panel. This continuous flexible printed circuit substrate is then used with a precisely positioned indexing system.

Claims

1. A method for manufacturing an electroluminescent lamp and membrane switch assembly, said method comprising the following steps of:

forming rear capacitive plate electrodes from a metal foil by embossing said metal foil onto a first surface of an insulating flexible plastic film;

forming front capacitive electrodes from a metal foil by embossing said metal foil onto said first surface of said insulating flexible plastic film;

forming electrical distribution pathways connected to said capacitive electrodes from a metal foil by embossing said metal foil onto said first surface of said insulating flexible plastic film;

forming electrical terminations that connect to said electrical distribution pathways from a metal foil by embossing said metal foil onto said first surface of said insulating flexible plastic film;

forming a pair of switch contact electrodes from a metal foil by embossing metal foil onto the second surface of said insulating flexible plastic film;

forming electrical distribution pathways connected to said pair of switch contact electrodes from a metal foil by embossing said metal foil onto said second surface of said insulating flexible plastic film;

forming electrical terminations that connect to said electrical distribution pathways from a metal foil by embossing said metal foil onto said second surface of said insulating flexible plastic film;

forming a switch contact shunt electrode from a metal foil by embossing said metal foil onto said second surface of said insulating flexible plastic film;

applying said insulating flexible plastic film to an optically registered indexing system, said optically registered indexing system to precisely position said insulating plastic film for further electroluminescent lighted membrane switch construction processing;

applying a layer of capacitive dielectric to said metal foil rear capacitive plate electrodes, said capacitive dielectric for electrically isolating said rear capacitive plate electrodes;

applying a layer of electroluminescent phosphor to said capacitive dielectric layer, said electroluminescent phosphor layer for precisely defining an area of illumination;

applying an electrically conductive layer to said electroluminescent phosphor layer, said electrically conductive layer contacting said front capacitive electrodes thereby creating a light transmissive second capacitive plate;

applying an insulating layer to cover said second capacitive plate, said insulating layer extending to cover said electrical distribution pathways;

die cutting said insulating flexible plastic film in a pattern comprising a three part, two hinged foldable electroluminescent illuminated membrane switch subassembly having a tab portion extending therefrom, said tab portion supporting said electrical terminations connecting to said electrical distribution pathways, thus creating an electroluminescent illuminated membrane switch subassembly;

embossing said insulating flexible plastic film in a pattern comprising a serpentine spring member substantially forming a surrounding frame element that is offset from the perimeter of said switch contact shunt electrode and permanently deforming said switch contact shunt and said insulating flexible plastic film to form a switch actuator surface bordered by said frame element;

folding a first portion from said electroluminescent illuminated membrane switch subassembly, said first portion folded at the location of one of two said hinges and substantially positioning said switch contact shunt electrode opposite said switch contact electrodes; and

folding a second portion from said electroluminescent illuminate membrane switch subassembly, said second portion folded at the location of the remaining said hinge, thus overlapping said second portion above said first portion and substantially positioning said rear capacitive plate electrode opposite said switch contact shunt electrode.

2. The method of 1 wherein said metal foil is die cut to form said rear capacitive plate electrodes.

3. The method of 1 wherein said metal foil is chemically etched to form said rear capacitive plate electrodes.

4. The method of 1 wherein said metal foil is laser cut to form said rear capacitive plate electrodes.

5. The method of 1 wherein said rear capacitive plate electrodes is a layer of electrically conductive ink.

6. The method of 1 wherein said rear capacitive plate electrodes is a layer of deposited metal.

7. The method of 1 wherein said metal foil is die cut to form said front capacitive electrodes.

8. The method of 1 wherein said metal foil is chemically etched to form said front capacitive electrodes.

9. The method of 1 wherein said metal foil is laser cut to form said front capacitive electrodes.

10. The method of 1 wherein said front capacitive electrodes is a layer of electrically conductive ink.

11. The method of 1 wherein said front capacitive electrodes is a layer of deposited metal.

12. The method of 1 wherein said metal foil is die cut to form said electrical distribution pathways.

13. The method of 1 wherein said metal foil is chemically etched to form said electrical distribution pathways.

14. The method of 1 wherein said metal foil is laser cut to form said electrical distribution pathways.

15. The method of 1 wherein said electrical distribution pathways is a layer of electrically conductive ink.

16. The method of 1 wherein said electrical distribution pathways is a layer of deposited metal.

17. The method of 1 wherein said metal foil is die cut to form said electrical terminations.

18. The method of 1 wherein said metal foil is chemically etched to form said electrical terminations.

19. The method of 1 wherein said metal foil is laser cut to form said electrical terminations.

20. The method of 1 wherein said electrical terminations is a layer of electrically conductive ink.

21. The method of 1 wherein said electrical terminations is a layer of deposited metal.

22. The method of 1 wherein said metal foil is die cut to form said pair of switch contact electrodes.

23. The method of 1 wherein said metal foil is chemically etched to form said pair of switch contact electrodes.

24. The method of 1 wherein said pair of switch contact electrodes is a layer of electrically conductive ink.

25. The method of 1 wherein said metal foil is laser cut to form said pair of switch contact electrodes.

26. The method of 1 wherein said metal foil is die cut to form said switch contact shunt electrode.

27. The method of 1 wherein said metal foil is chemically etched to form said switch contact shunt electrode.

28. The method of 1 wherein said switch contact shunt electrode is a layer of electrically conductive ink.

29. The method of 1 wherein said metal foil is laser cut to form said switch contact shunt electrode.

30. The method of 1 wherein said switch contact shunt electrode is embossed to form a substantially convex snap dome contact.

31. The method of 1 wherein said switch contact shunt located on said second surface of said insulating flexible plastic film is substantially positioned opposite of said rear capacitive plate located on said first surface of said insulating flexible plastic film.

32. The method of 1 wherein said first folded portion of said insulating flexible plastic film is embossed to form a serpentine spring member surrounding a die cut aperture opening substantially shaped and sized to allow passage of said switch shunt electrode therethrough, and said aperture opening substantially oppositely positioned above said switch contacts.

33. The method of 1 wherein said light transmissive front capacitive plate is a layer of conductive ink.

34. The method of 1 wherein said light transmissive front capacitive plate is a conductive metal oxide coated plastic film.

35. The method of 1 wherein said light transmissive front capacitive plate is a conductive ink containing metal oxide.

36. The method of 1 wherein said light transmissive front capacitive plate is a sputter coated layer containing metal oxide.

37. The method of 1 wherein said light transmissive front capacitive plate is a plasma spray coated metal oxide.

38. The method of 1 wherein said light transmissive front capacitive plate is a conductive organic polymer comprised of PEDOT (Poly-3,4-Ethyelenedioxithiophene).

39. The method of 1 wherein said electroluminescent phosphor layer is an electroluminescent phosphor particle imbued plastic film.

40. The method of 1 wherein said electroluminescent phosphor layer is an electroluminescent phosphor particle imbued ink.

41. The method of 1 wherein said electroluminescent phosphor layer is applied via plasma spray.

42. The method of 1 wherein said capacitive dielectric layer is a plastic film.

43. The method of 1 wherein said capacitive dielectric layer is ink.

44. The method of 1 wherein said capacitive dielectric layer is applied via plasma spray.