Description: A propietary, alkaline copper-ammonia complex etchant was evaluated for use in production of printed wiring boards (PWBs). A better etchant than the standard chromic-sulfuric acid etchant was needed because of the numerous disadvantages associated with use of the latter. Testing of the alkaline etchant involved etching identical circuit patterns with both etchants, micro-sectioning samples, and measuring conductor widths. There was little dimensional difference between the two systems. Inspection of the panels etched in the alkaline etchant indicated that conductor widths were within dimensional tolerances and that undercutting of the masking was less than expected. Parts masked with tin-lead plate and alkaline etched were tested for solderability; results were excellent. Because of this evaluation, the production process was changed to incorporate the alkaline etchant. It has been used for production etching of PWBs since June 1973.
Date: September 1, 1976
Creator: Evans, M. E.
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