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JULY 2026 I I-CONNECT007 MAGAZINE 47 surface of the copper during the galvanic reaction. As copper is displaced, the silver deposits on the copper surface, forming a silver "roof" over the voided area. Upon assembly, the silver dissolves, leaving microvoids as shown in Figure 2. This issue was named "champagne bubbles." The alkaline-based process will not attack the copper as aggressively as any nitrate-based process. In addition, the silver ions in the alkaline silver process are chelated. This allows for more controlled deposition of silver. This results in a denser, less porous silver deposit. While gold is slightly less conductive than silver, the benefits of an immersion gold deposit would outweigh any additional signal loss due to the pres- ence of gold over silver. In addition, gold provides T RO U B L E I N YO U R TA N K Figure 2: Voids also known as champagne bubbles. additional protection for the silver and enhances wire-bonding performance. With a thin coating of immersion gold, the underlying silver is protected from tarnishing. In general, the ISIG process presents a more controllable and efficient final finish for 5G/6G. The result of a nitrate-free immersion silver process is a deposit with insertion loss identical to copper, and now providing protection very close to electroless nickel. This makes nitrate-free immersion silver a viable process for 5G and millimeter-wave appli- cations well into the future. I-CONNECT007 Michael Carano brings over 40 years of electronics industry experience with special expertise in manufac- turing, performance chemicals, metals, semi- conductors, medical devices, and advanced packaging. To read past columns, click here.