Issue link: https://iconnect007.uberflip.com/i/1471044
48 PCB007 MAGAZINE I JUNE 2022 putting cold parts in a hot clay, sulfuric envi- ronment for a 24-hour cycle. When we plotted the results, ENIG was per- fect, and the nitrate-free process with post-dip was extremely close. Traditional nitrate-based silver was far behind (Figure 2). Since those findings, we reshaped the pro- cess, and do have a 5G solution for a final fin- ish. It is economical, conductive, solderable (and in fact, multi-cycle solderable), and most beneficially, addressing all the issues immer- sion silver had with corrosion. is new immersion silver process is a game- changer because cost, speed, and performance are all there. Today, ENIG is still dominating the final finish market, but this approach will not work in the very near future. 5G today is at one-tenth of its full potential, and as the signal speed increases, the options that can keep the cost down and performance high will become the new standards. PCB007 Denis Jacques is product manager of PWB products for Technic Inc. is was what we needed to get started. In our internal study, we compared ENIG, nitrate- based silver, and nitrate-free silver against dif- ferent types of corrosion. We wanted to prove our concept addresses corrosion issues and is superior to nitrate-based chemistry, much like the show Mythbusters. We believe we are bet- ter, let's do destructive testing to prove it! e three processes were plated, using the same test coupons. ey were all run as close as possible to best practice and we have tested the use of an organic post-dip for the two sil- vers. en we compared all parts for cosmet- ics, adhesion, solderability, nitric acid dip/sol- derability, horizontal micro-etch cycle, and creep corrosion. As expected, the cosmetics and adhesion were all good. Even the nitric dip was good for three tests; the nitrate-based fin- ish came out slightly yellow, but still solder- able. It was during the next two tests that we got a nice surprise. As expected, ENIG, came out perfect. But surprisingly, ENIG was followed very closely by the nitrate-free process using a post-dip. It was very close! e horizontal micro-etch was removing about 15 microinches of copper with each pass. We processed the parts—inspect, tape test, and if it passed, on to the next round— for 10 passes. e creep corrosion test involves Figure 2: Corrosion test of ENIG, nitrate-based silver, and nitrate-free silver finishes.