Letter 2025

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I have oxidation on my finish copper product surface (leadframe), my process are : etching-rinsing-stripping of photoresist by sodium hydroxide-rinsing-neutralizer by sulphuric acid-rinsing-antitarnish-DI rinsing-air blow-dry. The oxidation are 1)red dot 2)dark brown dot 3)black dot and this affect my production yield badly,any suggestion? Any help would be appreciated

Ken Chia
- Singapore

It sounds like you don't have a corrosion inhibitor that is specifically used for copper in the acids and rinses after the acids. Sherwin Williams makes one called Cobratec. The chemical name is tolytriazole. Just a little in the acid and rinses should help.

Good Luck,

Craig A. Burkart Nalco Company - Naperville, IL

The COBRATEC line of corrosion inhibitors, primarily for copper, its alloys and silver, is now part of the PMC Specialties Group, Inc.

Bruce Fredrickson
- Berlin, NJ

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