Issue link: https://iconnect007.uberflip.com/i/1471044
44 PCB007 MAGAZINE I JUNE 2022 Feature Article by Denis Jacques TECHNIC INC. About three decades ago, immersion silver, a nitrate-based process, gained a lot of market share in the world of PCB final finishes. More economical than ENIG, flat, solderable, and conductive, it had everything going for it— everything but corrosion resistance in a harsh environment, that is. Champagne voids were also an issue, along with line reduction. But the worst drawback, the characteristic that made the part short over time, was creep corrosion. A build-up of copper sulfide salt that grows in contact with a sulfur-rich environment, heat, and moisture resulted in failures in the field. is was enough to scar the process for good. e market today for silver as a final finish is pretty meager and therefore does not justify much research. Fortunately, there is an alterna- tive immersion silver, originally developed for other applications, that has proven to be a reli- able solution. Immersion silver is nitrate-free, slightly alkaline, and deposits a slow, pore- free pure silver deposit. I had a strong feeling that this process would be a solid alternative to nitrate-based chemistry, yielding the benefits without the drawbacks. Work started about 10 years ago with this product, on a very limited basis, because as mentioned before, the interest in silver is just not there. One of our customers raised the fact that their silver was acting somehow gal- vanic, and some isolated lines were reduced. e customer works in the RF field, and this was a major issue for them. I offered to test this bath, feeling that it could be a solution to the problem. Plating on Silver: What's Old Is New Again