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Maybe in reply to: Charles_Barker@i-o.com: "HASL Microetch"

As a micro-etch (either type) becomes saturated with copper, there is a tendency for it to redeposit copper sulfate crystals, especially when it hits a cold rinse. These tiny copper sulfate crystals will cause dewetting in HASL. It is common practice to follow the micro-etch rinse with a sulfuric acid dip of 5-10% and rinse. This redissolves the copper sulfate. Another fix is to change (persulfate) or regenerate (peroxide-sulfuric) the micro-etch more frequently, to prevent copper buildup in the solution. Also, maintain enough acid in the etch (see supplier) to keep the maximum amount of copper in solution.

Patty