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Copper Corrosion from Clear Chromate

October 15, 2012

Q. We are a Thermal Solutions company that make liquid cold plates for the electronics industries. We have a product that went out for "Chemical Conversion Coat per MIL-DTL-5541F, Type II, Class 1A, Clear". We have had the parts processed many times and they have come back without fail. They have looked great. But this current lot has come back completely different. The copper tube has almost turned to a reddish color. On some plates, the tubing has actually turned black and has recessed into the plate about .005". I have never seen copper react like this for a clear chromate process. They grey substance you see is a thermal compound. Has anybody ever seen a reaction like this? Any ideas why something like this may have happened? Thank you for your help in advance!

copper tube corrosion after clear chromate 1

Rob McCarter

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