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Blistered Plating on Beryllium Substrate
Q. I have been experiencing problems to plate beryllium copper and leaded nickel alloys. These base metals show peeling and blisters when plated with copper, nickel and gold. The adhesion problem is from the base metal. Our process is an automatic process that require a hand pretreatment. Somebody can tell me the best way to clean and activate this base material.
Thanks,
- El Segundo, California, USA
2001
2003
Q. Colleagues,
I'm in a plating laboratory environment, developing a process for plating on beryllium. Once developed, this process will need to be semi-productionized for low volume, hi-reliability applications.
Roughly stated, our process is: solvent cleaning, flowing DI rinse, soak cleaning in a soap, flowing DI rinse, acid pickling, flowing DI rinse, zincating, flowing DI rinse, copper striking....and then the blisters occur. We're using the standard Rochelle bath and immediately after striking, the blisters are evident under magnification in small quantities, and after subsequent vacuum baking they are more pronounced. Adhesion away from the blisters appears to be very good: tape test, scrape test and thermal shock have no effect.
We've made the following process changes: added a cathodic electroclean in a caustic soap cleaner in place of the soak cleaner; added ultrasonic cleaning with the solvent; added ultrasonic rinses between steps. We've seen a decrease in number, but the blistering continues.
The best results, virtually no blistering, was after a
pumice [on
eBay or
Amazon] scrub was introduced after the solvent soak, but I'd prefer NOT to manually scrub each part and chance the embedding or trapping of pumice particulate into the surface or blind areas. We've used both instrument and standard grade beryllium. Ideas/suggestions ?
Thanks in advance,
avionics Tampa, Florida
A. I stopped reading your message when I got down to "Rochelle", which tells me you are striking in Cyanide Copper.
Beryllium forms an insoluble with cyanide. You cannot get adhesion by copper cyanide striking.
Plate first in ANY acid solution including Copper sulphate. And, OH, you do not need a zincate, just flash acid copper direct on the cleaned Be-Copper.
Robert H Probert
Robert H Probert Technical Services
Garner, North Carolina
2003
Q. Mr. Probert,
I appreciate the response. We eliminated the cyanide strike shortly after posting the question. We tried several more pre-treatment steps and could only minimize the blistering, could not eliminate it. We then tried an electroless nickel after the zincate and we have reasonable success, no blisters.
Please keep in mind that we're working with pure beryllium, not Be-Cu. Pure Be needs the zincate in the same way and for the same reasons that aluminum does.
Thanks,
avionics Tampa, Florida
2003
A. Can you use a different finish on pure Be other than copper? What is the key property you are looking for, electrical conductivity?
Gus Vallejo- Minneapolis, Minnesota, USA
2003
Q. We are having a similar problem on "CAST STEEL SUBSTRATE" which contains 1 1/2 chrome & .5 percent molybdneum. Any suggestions?
HARSHAL h. BHATTElectroplating - Surat, Gujrat India
2003
A. Hello Harshal. While it's easy for you to recognize that you have a 'similar problem' to Mr. Denney's, it is not so easy for me. I unfortunately don't know whether you are implying that you are using rochelle copper, or an acid copper flash, or zincate, or electroless nickel. And your pretreatment for steel is or isn't identical to Mr. Denney's pretreatment for beryllium? And you had no blistering when you hand scrubbed parts but you don't want to continue doing so, or you still had blistering even with hand scrubbing? Please try to describe your own problem, with details, so that people can try to help. Thanks!
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2003
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