Browse Prior Art Database

High Current Density Copper Plating of High Aspect Ratio Boards

IP.com Disclosure Number: IPCOM000102970D
Original Publication Date: 1990-Apr-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 46K

Publishing Venue

IBM

Related People

Edwards, RD: AUTHOR

Abstract

Disclosed is a process for electroplating copper on relatively thick printed circuit boards with small diameter holes at higher than normal current densities.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 67% of the total text.

High Current Density Copper Plating of High Aspect Ratio Boards

      Disclosed is a process for electroplating copper on relatively
thick printed circuit boards with small diameter holes at higher than
normal current densities.

      Thick composites with small diameter drilled holes create a
problem for electroplating boards since the surface is at a higher
potential than in the hole and will, thus, plate thicker.  By
modifying chemical parameters of the bath and reducing the current,
the difference between surface and hole plating can be reduced.  As
the plating current density is decreased, the amount of time required
for plating the same thickness of copper increases.  Typical plating
times for 1 mil of copper on a board 126 mils thick with 18 mil
holes, 7:1 aspect ratio, is 2 hours.

      Faster plating times are possible using the same tank design as
the conventional process, without degrading the ratio of hole plating
vs. surface plating, by adjusting some of the chemical parameters.
The process listed below differs from a conventional process in that
it operates at a higher temperature for better solution conductivity,
higher brightener and leveller concentrations for better suppression
of plating in the high current density areas, and higher current
densities that cut plating time up to 50%.

      PARAMETER                 SET POINT      LIMITS
Copper (from copper sulfate)     14 g/l      11 -  16 g/l
Sulfuric a...