47015

Comparisons of Sn finishing vs. Ag finishing [Malaysia] 

November 12, 2007

My component supplier wants to change their component lead finishing from matte Sn to electroplated Ag. I would like to understand the pros and cons of both types of platings.

Yi-Feng Hwang
Product Engineer - Penang, Malaysia

Hello, Y-Feng. As we have noted on other occasions, to try to list the pros and cons of two different finishes without knowing the application is like trying to list the pros and cons of travel by rail vs. travel by ship without knowing the destination. Please tell us about your parts. Is appearance important? Corrosion resistance? Is it a contact surface? Will they be soldered? Is a subsequent electroplating sometimes applied? What advantage does your component supplier claim? Thanks.

Ted Mooney, P.E.  finishing.com Brick, New Jersey

Hi Hwang
Just go ahead and do it.But before doing it have a Memorandum of understanding signed by both of u so that your supplier does not come back and claim the losses if any, by the change of the process. Also please do not forget to post the outcome in the same forum for all of us to know.
good luck.

T.K. Mohan     plating process supplier  Mumbai, India

Ted, thanks for your reply.
The plating is the terminal finish for an electronic component that needs to be soldered eventually. The parts are shipped in Moisture Barrier Bag and might be kept in the warehouse for >6months. Appearance is not important. My concerns are more on wetting, solderability, shelf life etc. My supplier claimed that there is not much difference in soldering Sn plated parts and Ag plated parts, except that Ag tarnishes easily when exposing environment with sulfur but will not have worry of whisker growth like Sn whisker. However, I've also read through other literature that talked about Ag undergoing dendritic growth. What is the risk in this case when the Ag plated terminals have been soldered?

Yi-Feng Hwang
- Penang, Malaysia