Process for preparing the through hole walls of a printed wiring board for electroplating

Abstract

Abstract In the process for electroplating the walls of through holes in a laminated printed wiring board comprised of at least one non-conducting layer laminated to at least two separate conductive metal layers, which comprises the steps: (a) contacting said printed wiring board having said through holes with a liquid dispersion of carbon black comprised of: (1) carbon black particles having an average particle size of less than about 3.0 microns in said dispersion; (2) an effective dispersing amount of a surfactant which is compatible with said carbon black; and (3) a liquid dispersing medium, wherein the amount of carbon black is sufficient to coat substantially all of said non-conducting surfaces and is less than about 4% by weight of said liquid dispersion; (b) separating substantially all of the liquid dispersing medium from said dispersion, thereby depositing said carbon black particles in a substantially continuous layer on said non-conducting portions of said hole walls; (c) microetching said metal layers of said printed wiring board to remove deposited carbon black therefrom; (d) rinsing said printed wiring board to remove residual microetch therefrom; and (e) electroplating a substantially continuous metal layer over the deposited carbon black layer on said non-conducting portions of hole walls, thereby electrically connecting said metal layers of said printed wiring board; wherein said improvement comprises: contacting said deposited carbon black particles after step (b) and before step (c) with aqueous solution of gas-forming compound selected from an alkaline carbonate, an alkaline sulfite and mixtures thereof.

Inventors

• 👤 Anthony M. Piano

Bibliographic Details