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Adhesive doesn't stick to Chemfilm

We are a high volume manufacturer of an electrical component that is made of cast aluminum. This part is chem filmed and is supplied to us from an offshore source. We use an adhesive to bond a plastic part to the aluminum substrate and have occasions when the adhesive bond does not stick. Is there a chemical in the chem film process that will not allow the adhesive to stick to some parts?

Pete Capone
electronics - Oxnard, California, USA
2004

2004

If the chromate is too heavy then paint and adhesives will peel. If the applicator did not remove all the smut which is common to castings, then the chromate did not adhere and the adhesive will not adhere.

Clean (stay out of the alkali etch) then deox in 100% nitric acid with 2 pounds per gallon ammonium bifluoride, then apply the chromate very lightly.

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina

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