HOME FAQs BOOKS JOBS: Help Wanted Suggestions you are here: Hotline/Forum => Letter 2027

Electroless nickel tarnished with rainbow colors during heat treatment

I am an electroplating jobber in Penang, Malaysia. My company provide gold, silver, palladium-nickel, tin, tin-lead and electroless nickel (EN) plating to the electronic and electrical industries.

I had lately doing some EN coating jobber that require heat treatment, the job pieces tarnished with rainbow colors in the heating chamber. What caused this? Could you share some experience with me?

After the EN coating we passivate the surface with dilute chromic acid. Then heated in nitrogen gas purging oven with the following profile:

Ramp up from 140 degree F to 750 degree F in 30 minutes
Soak at 750 degree F for 75 minutes.
60 minutes to cool down to 140 degree F
Remove from oven.

Thank you and best regards,

Keat-Seng Ong
- Malaysia

Rinsing before bake must be thorough. Consider using D.I. water.

Richard Painter
- Cleveland, Ohio

+++

I agree with the better rinsing. Also, is the 750F necessary. What are you trying to achieve, higher hardness?

Robert Sachs
- Canada

ANSWER or FOLLOW UP POST an unrelated QUESTION HOT Topics

Disclaimer: It is not possible to diagnose a finishing problem or the hazards of an operation via these pages. All information
presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The
internet is largely anonymous; some names may be fictitious and some recommendations may be deliberately harmful.

If you are seeking a product or service related to metal finishing, please check these Directories: