Letter 38029

Hardened Silver Plating for Printed Circuit Boards [California] 

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I am a PCB manufacturer that has been asked by a customer to find a replacement finish to our current plating of Rhodium/Nickel. The customer likes the hardness of the Rhodium, but it is too expensive. We've tried Hard Gold, but it's not hard enough. Someone mentioned Hardened Silver as a possible replacement. Apparently, hardened silver is plated on coins but I can't find anyone who plates this metal to print circuit boards. Furthermore, the only specification that I can find for silver (QQ-S-365) makes no reference to the hardness.

Does anyone have suggestions on another possible alternative to Rhodium....or does anyone have any additional information about Hardened Silver and where I can find it? Thank you in advance!

Dara Ferris
PCB Manufacturer - Newbury Park, California, USA

The answer is going to depend on the properties your customer is looking for in the finish. How hard does the finish need to be? Does it have to be solderable? For how long? Over the whole surface, or just edge connectors? Get more specific and the answers get easier.

James Totter, CEF - Tallahassee, FL

Dara

Hard Gold on PCB's attains a hardness of 200 and more vickers.Alloys are Gold nickel and Gold cobalt.

Silver though hard will not exceed the conductivity and hardness provided by gold Tarnish resistance is another issue where silver is not a preferred route.

Regards

Asif Nurie Atlanta Global Limited New Delhi, India

You can try palladium plating. Hardness is 250-300 DPH (rhodium=900 DPH). According to Fischer,Weimer: Precious Metal Plating,Teddington 1964. Good luck!

Goran Budija
- Zagreb, Croatia

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