Method for the production of printed circuit boards

• US 6,035,527 A
• Filed: 05/12/1997
• Issued: 03/14/2000
• Est. Priority Date: 05/18/1996
• Status: Expired due to Term

• Current Assignee: Multilayer Technology, Inc. (DOVatron International, Inc.)
• Original Assignee: Ingenieurburo Tamm Factory Innovations
• Inventors: Tamm, Wilhelm
• Primary Examiner(s): Arbes, Carl J.
• Application Number:
  US08/854,468
• Time in Patent Office: 1,037 Days
• Field of Search: 29/852, 29/846, 427/97
• US Class Current: 29/852
• CPC Class Codes: H01K 3/10 Machines therefor
• CPC Class Codes: H05K 2201/0376 Flush conductors, i.e. flush with the surface of the printed circuit
• CPC Class Codes: H05K 2201/09036 Recesses or grooves in insulating substrate
• CPC Class Codes: H05K 3/0032 of organic insulating material
• CPC Class Codes: H05K 3/027 the conductive material being removed by irradiation, e.g. by photons, alpha or beta particles
• CPC Class Codes: H05K 3/048 using a lift-off resist pattern or a release layer pattern
• CPC Class Codes: H05K 3/107 by filling grooves in the support with conductive material H05K3/045, H05K3/101, H05K3/1258 and H05K3/465 take precedence
• CPC Class Codes: H05K 3/108 by semi-additive methods; masks therefor characterised by metallic etch mask H05K3/062; electroplating methods or apparatus H05K3/241
• CPC Class Codes: H05K 3/146 By vapour deposition
• CPC Class Codes: H05K 3/185 by making a catalytic pattern by photo-imaging
• CPC Class Codes: H05K 3/426 initial plating of through-holes in substrates without metal
• CPC Class Codes: Y10T 29/49155 Manufacturing circuit on or in base
• CPC Class Codes: Y10T 29/49165 by forming conductive walled aperture in base

Abstract

A method for the production of printed circuit boards comprises the steps of producing recesses (2, 3, 4, 5) and/or through holes (2a) in a substrate (1) made from insulating material, in particular by means of laser-ablation, wherein the recesses and/or through holes correspond to the desired structure of conductive tracks and/or plated through holes; introducing a base layer (6) on one or both sides of the substrate (1); and introducing a conductive material (7) onto the base layer (6) which is catalytic and/or activating relative to the conductive material (7). The base layer (6) is selectively removed from the substrate (1), except in the recesses and/or in the through holes, by means of laser-ablation prior to introduction of the conductive material (7). Processing of the surface of the conductive material, the base layer or of the substrate is no longer necessary.

Claims

1. A method for the production of printed circuit boards, the method comprising the steps of;

a) Removing material from a substrate to form a first recess in a first side of said substrate, said first recess having a bottom and a side surface, said first recess side surface defining a first recess width, said first recess for generating a first line of a circuit pattern;

b) removing material from said substrate to form a second recess in a second side of said substrate, across from and aligned with said first recess, said second recess having a bottom and a side surface, said second recess side surface defining a second recess width, said second recess for generating a second line of a circuit pattern;

c) removing material from said substrate to form, in one of said first and said second sides, a third recess having a bottom and a side surface, said third recess for generating a third line of a circuit pattern;

d) removing material from said substrate to produce a through hole centered in and connecting said first recess and said second recess, said through hole having an inner surface defining a width less than said first recess width and less than said second recess width;

e) covering said first, second and third recess side and bottom surfaces and said through hole inner surface with a base layer;

f) selectively removing said base layer deposited in step e) from said first, second and third recess side surfaces while leaving said base layer on said first, second, and third recess bottom surfaces and on said through hole inner surface; and

g) applying a conductive material, following step f), to cover said base layer and to cover said first, second, and third recess side surfaces, wherein said base layer is at least one of catalytic and activating relative to said conductive material.

2. The method of claim 1, wherein step c) comprises forming said third recess in said first side and steps a) and c) are performed prior to step b).

3. The method of claim 1, wherein said base layer is selectively removed by laser-ablation in step f).

4. The method of claim 1, wherein step d) follows step c), the method further comprising the step of:

c1) applying a removable cover layer to said substrate following step c) and prior to step d).

5. The method of claim 1, further comprising the step of:

e1) applying electromagnetic radiation to said base layer to convert said base layer into at least one of a catalytic and activating layer.

6. The method of claim 1, wherein a chemical wetting solution is used in step f) to selectively remove said base layer.

7. The method of claim 1, wherein said base layer is introduced onto said substrate in step e) using one of a chemical wetting process, physical vapor phase deposition, and chemical vapor phase deposition.

8. The method of claim 1, wherein said base layer is one of a metal oxide compound and an organic palladium compound.

9. The method of claim 1, wherein said conductive material is applied using one of chemical deposition and galvanic metallic deposition.

10. The method of claim 1, further comprising the step of introducing an additional metallic layer onto said conductive material, said additional layer being flush with said first and said second sides of said substrate.

11. The method of claim 1, further comprising removing said conductive material and said base layer until said conductive material is flush with said first and with said second sides of said substrate.

12. The method of claim 1, further comprising irradiating said first, second and third recesses and said through holes with electromagnetic radiation, and depositing a conductive material using a wet chemical bath.

13. The method of claim 1, wherein step g) comprises applying conductive material to said substrate to completely fill said first, second and third recesses and said through hole, and further comprising removing said conductive material until said conductive material is flush with said first and said second sides of said substrate.