Process for through-hole plating of two-layer circuit boards and multilayers

• US 5,403,467 A
• Filed: 01/19/1993
• Issued: 04/04/1995
• Est. Priority Date: 01/29/1992
• Status: Expired due to Term

• Current Assignee: Heraeus Clevios GmbH (Heraeus Holding GMBH)
• Original Assignee: Bayer AG
• Inventors: Jonas, Friedrich, Wolf, Gerhard-Dieter
• Primary Examiner(s): Niebling, John
• Assistant Examiner(s): Wong, Edna
• Application Number:
  US08/005,779
• Time in Patent Office: 805 Days
• Field of Search: 205/125, 205/185, 427/97
• US Class Current: 205/125
• CPC Class Codes: C25D 5/56 of plastics
• CPC Class Codes: H05K 2201/0329 Intrinsically conductive polymer [ICP]; Semiconductive polymer
• CPC Class Codes: H05K 2203/0796 Oxidant in aqueous solution, e.g. permanganate
• CPC Class Codes: H05K 3/424 by direct electroplating
• CPC Class Codes: H05K 3/427 initial plating of through-holes in metal-clad substrates

Abstract

A process for through-hole plating of two-layer circuit boards and multilayers using polythiophenes as a conductive agent on the side walls of through-holes for the direct through-hole plating and to the circuit boards and multilayers thus produced.

Claims

1. A process for the production of through-hole plated circuit boards and multilayers, wherein a conductive layer of a polythiophene is produced on the walls of the through-holes provided in the board by treatment with an emulsion of 3,4-ethylenedioxythiophene, said process comprising the following steps:

a) formation of through-holes in copper-laminated circuit boards (base materials);

b) oxidative treatment of the through-holes with an alkaline potassium permanganate solution;

c) rinsing with water;

d) treatment with an emulsion consisting essentially of 3,4-ethylenedioxythiophene and water;

e) treatment with an acid;

f) rinsing with water; and

g) electrodeposition of copper.

2. A process as claimed in claim 1, wherein steps d and e are combined into a single step.

3. A process as claimed in claim 1, wherein the emulsion in step (d) consists of water and 0.1 to 10% by weight of 3,4-ethylenedioxythiophene.

4. A process as claimed in claim 1, wherein the emulsion in step (d) consists of water and 0.2 to 5% by weight of 3,4-ethylenedioxythiophene.

5. A process as claimed in claim 1, wherein the emulsion in step (d) consists of water and 0.5 to 2.5% by weight of 3,4-ethylenedioxythiophene.