Where the
world gathers for metal finishing
Q&As since 1989


-----

HELP ON PLATING A COPPER PIN

2000

Help!

I am a small woman-owned electronics company. I had pins made out of copper C14500. I had them annealed at 600 degrees F for 1 hour. This was to soften it up. The pin is swaged into a circuit board.

Now I am sending them to the platers. My customer requires 200 microinches Tin/Lead (SnPb 90/10) over 80-120 Microinches nickel and I was told if I have them with an under coat of nickel there is a very high chance the nickel will cause the copper to be brittle. This is so important to me. I want my customer to get nothing but the best. I have no way of checking if the copper makes it brittle. I can only swage the finished pin into FR4 Material and check if there is any cracks.

If there is anyone out there that can help me, I forever be in your debt. Please Help!

Michelle Pease
electronics - Tyngsboro, Massachusetts

The nickel plate does not by itself make the copper brittle, it is the stress in the plated nickel and the adsorbtion of hydrogen gas into the pores of the copper. (please excuse my spelling, not a good am) One suggestion is to try electroless nickel plating since it is likely that little hydrogen will be evolved during the autocatalytic process as opposed to the electrolytic. Also look for a vendor that is using a process that is compressivley stressed. Do not let your vendor overlook the fact that cleaning and pickling of the copper will add to the hydrogen adsorbtion and need to be conducted in a manner to minimize same.

Gene Packman
process supplier - Great Neck, New York
2000

---

All alloy C14500 materials have some phosphorus added, which effectively deoxidizes the copper. The tellurium present generally is in the form of a fine oxide dispersion. There are C14510, C14520 and C14530 variations also, with varying trace amounts of P (and Sn), but these may not be available except by custom order. For your type of application, metallurgically, one would expect it to be difficult to cause "hydrogen embrittlement", as seen when oxygen bearing coppers like C11000 are exposed to hydrogen. My company has produced alloy 145 fin copper for heat exchangers, made by soldering fins to copper tube, using a Pb/Sn molten bath process. The purpose of the elements in 145 is to give it a higher softening temperature. Some residual coldwork strength will be retained at soldering temps, which is probably the objective for your customer specifying it for his application.

W. Carl Erickson
- Rome, New York
2000