Three dimensional plating or etching process and masks therefor

• US 4,985,116 A
• Filed: 02/23/1990
• Issued: 01/15/1991
• Est. Priority Date: 02/23/1990
• Status: Expired due to Fees

• Current Assignee: Mint Urban Technologies Limited
• Original Assignee: Mint Urban Technologies Limited
• Inventors: Johnson, William L., Strickland, William C., Mettler, John H., Zaderej, Victor V.
• Primary Examiner(s): Powell, William A.
• Application Number:
  US07/484,387
• Time in Patent Office: 326 Days
• Field of Search: 219/121.68, 219/121.69, 219/121.85, 430/5, 430/313, 430/314, 430/315, 430/316, 430/318, 427/96, 427/98, 204/15, 204/20, 204/23, 204/38.4, 204/38.5, 204/38.7, 156/643, 156/656, 156/659.1, 156/666, 156/645, 156/212, 156/242, 156/277, 156/285, 156/902, 156/345, 428/195, 428/199, 29/846
• US Class Current: 438/674
• CPC Class Codes: G03F 1/68 Preparation processes not covered by groups G03F1/20 - G03F1/50
• CPC Class Codes: H05K 1/0284 Details of three-dimensional rigid printed circuit boards H05K1/119 takes precedence; shaping of the substrate H05K3/0014
• CPC Class Codes: H05K 2203/056 Using an artwork, i.e. a photomask for exposing photosensitive layers
• CPC Class Codes: H05K 2203/085 Using vacuum or low pressure
• CPC Class Codes: H05K 2203/107 Using laser light shaping a substrate by laser ablation H05K3/0026
• CPC Class Codes: H05K 3/0002 for manufacturing artworks for printed circuits
• CPC Class Codes: H05K 3/0082 characterised by the exposure method of radiation-sensitive masks
• CPC Class Codes: Y10T 156/1028 by bending, drawing or stretch forming sheet to assume shape of configured lamina while in contact therewith

Abstract

In a process for plating or etching metalization patterns on the surface of a three dimensional substrate, a flexible plastic mask is fabricated by first coating the surface of a thin plastic sheet with vacuum formable ink. The mask is then molded into the shape of the surface into which the pattern is to be formed. A low power YAG laser is used to remove areas of the ink through which light is to be allowed to pass. This mask may then be used in either a print and plate process or a print and etch process by drawing the mask into intimate contact with the workpiece by applying a vacuum between the mask and the workpiece. The workpiece may then be exposed to light through the clear areas of the mask.

Claims

1. A method for fabricating a mask, comprising in combination the steps of:

coating one surface of a sheet of transparent vacuum formable material with a vacuum formable ink;

vacuum forming said sheet; and

removing portions of said ink to reveal transparent areas of said mask.

2. The method of claim 1, wherein said removing step is carried out by illuminating said portions of said ink with a low power laser.

3. The method of claim 2, wherein said laser is a YAG laser.

4. The method of claim 1, wherein said sheet is approximately 0.005 to 0.050 inch in thickness.

5. The method of claim 2, wherein said ink is removed from said surface by illuminating said surface through said transparent material.

6. The method of claim 2, wherein said ink is removed from said surface by illuminating said surface from the inked surface of said sheet.

7. The method of claim 2, wherein said laser comprises a computer controlled laser.

8. The method of claim 7, wherein said laser can be controlled with five degrees of freedom.

9. The method of claim 2, wherein said laser has a power output of less than about 50 watts.

10. A method for fabricating a mask, comprising in combination the steps of:

coating one surface of a sheet of transparent vacuum formable material having thickness between 0.005 and 0.050 inch with a vacuum formable ink;

vacuum forming said sheet; and

removing portions of said ink to reveal transparent areas of said mask by illuminating said portions of said ink with a low power computer controlled YAG laser.

11. The method of claim 10, wherein said ink is removed from said surface by illuminating said surface through said transparent material.

12. The method of claim 10, wherein said ink is removed from said surface by illuminating said surface from the inked surface of said sheet.

13. A mask for use in a plating or etching process to be carried out on a workpiece, comprising in combination:

a vacuum formed sheet of flexible transparent plastic carrying the approximate shape of a surface of said workpiece;

a coating of an opaque material covering a portion of said sheet;

at least one area of said sheet having an absence of said opaque material to expose transparent plastic; and

registration means for providing alignment between said mask and said workpiece.

14. The mask of claim 13, wherein said sheet is made of material approximately 0.005 to 0.050 inch in thickness.

15. The mask of claim 13, further comprising a vacuum port for application of vacuum between said mask and said workpiece.

16. The mask of claim 13, further comprising a vacuum seal surrounding a periphery of said mask.

17. The mask of claim 13, wherein said registration means comprises at least one dimple adapted to seat within an aperture in said workpiece.

18. The mask of claim 13, wherein said plastic is transparent to ultraviolet light.

19. A method for applying a mask to a workpiece for use in a plating or etching process, the method comprising in combination the steps of:

providing a flexible mask having a surface which conforms with a surface of said workpiece;

registering said mask over said surface of said workpiece; and

drawing said mask into close contact with said workpiece by applying a vacuum between said mask and said workpiece.

20. The method of claim 19, further comprising the step of selectively exposing said workpiece to light through said mask.

21. The method of claim 20, wherein said light is produced by a non-collimated light source.

22. A method for processing a substrate, comprising in combination the steps of:

coating a plated substrate with photoresist;

installing a flexible mask over said coated substrate;

pulling said substrate and said mask into close contact by applying a vacuum between said substrate and said mask; and

exposing said coated substrate to light through said mask.

23. The method of claim 22, wherein said mask includes transparent areas and opaque areas, and wherein said transparent areas correspond to areas where metal is to be on said substrate.

24. The method of claim 22, wherein said mask includes transparent areas and opaque areas, and wherein said transparent areas correspond to areas where metal is to be removed from said workpiece.

25. The method of claim 22, further comprising the step of developing said exposed resist coated substrate to expose conductive areas.

26. The method of claim 22, wherein said light is non-collimated light.

27. The method of claim 22, further comprising the steps of electroless plating an insulating substrate prior to said coating step to produce said plated substrate.

28. The method of claim 27, further comprising the step of electroplating said electroless plated substrate with a conductive metal prior to said coating step to produce said plated substrate.

29. The method of claim 25, further comprising the step of electroplating said exposed conductive areas with a conductive material.

30. The method of claim 25, further comprising the step of etching away said exposed conductive areas.

31. The method of claim 25, further comprising the step of stripping away said developed resist.

32. The method of claim 31, further comprising the step of etching away conductive material exposed by the step of stripping away said developed resist.

33. The method of claim 31, further comprising the step of cleansing said substrate to remove a catalyst therefrom.

34. A method for printing and plating a substrate, comprising the ordered steps of:

molding an insulative substrate to a predetermined shape;

annealing said insulative substrate;

electroless plating said substrate with copper;

electroplating said substrate with a photoresist material;

drying and baking said photoresist material;

installing a flexible mask over said substrate;

pulling said flexible mask into close registration with said substrate by applying a vacuum between said mask and said substrate;

exposing said substrate to non-collimated light through said mask;

removing said mask from said substrate;

developing said photoresist material to expose areas of plated substrate while covering other areas of plated substrate;

electroplating said exposed areas of plated substrate with a conductive material;

etching said other areas of plated substrate to remove said plating on said other areas; and

stripping said photoresist to expose said other areas of plated substrate.

35. A method for fabricating a mask, comprising in combination the steps of:

providing a sheet of transparent material which turns opaque when exposed to laser light of adequate intensity;

forming said sheet of material into a predetermined shape; and

exposing said formed sheet to laser light of adequate intensity to cause selected areas of said formed sheet to turn opaque.

36. The method of claim 35, wherein said sheet of material is made of acrylic and wherein said laser burns opaque patterns in said selected areas.

38. The method of claim 35, wherein said laser burns opaque patterns in said selected areas.

37. A method for printing and etching a substrate, comprising the ordered steps of:

molding an insulative substrate to a predetermined shape;

annealing said insulative substrate;

electroless plating said substrate with a conductive material;

electroplating said substrate with a conductive material;

electroplating said substrate with a photoresist material;

drying and baking said photoresist material;

installing a flexible mask over said substrate;

pulling said flexible mask into close registration with said substrate by applying a vacuum between said mask and said substrate;

exposing said substrate to non-collimated light through said mask;

removing said mask from said substrate;

developing said photoresist material to expose areas of plated substrate while covering other areas of plated substrate;

etching away said exposed areas of plated substrate; and

stripping said photoresist to expose said other areas of plated substrate.