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MARCH 2021 I PCB007 MAGAZINE 47 EPIG vs. EPAG EPIG (electroless palladium/immersion gold) and EPAG (electroless palladium au- tocatalytic (electroless) gold) are nickel-free surface finishes that prevent the signal loss associated with electroless nickel deposits. ey are widely valued for high frequency RF applications. As discussed, thicker gold (greater than im- mersion gold) increases the wire bond operat- ing window. EPAG is promoted as the answer to the thickness limitations of immersion gold. Autocatalytic gold requires an immersion gold underlay and is a difficult bath to control. RAIG gold deposits a higher gold thickness than im- mersion gold in a single gold plating step. e hybrid EPIG/EPAG using RAIG gold produc- es the desired thickness without the complex- ity of an additional electroless bath. e concept of reduction-assisted immer- sion gold RAIG baths is coming into its own as more manufacturers and OEMs recognize its benefits, most notably the ability to deposit a thicker layer of gold (3–6 mins) with no corro- sion of the underlying nickel, in a single gold plating step. PCB007 George Milad is the national accounts manager for technology at Uyemura. To read past columns or contact Milad, click here. Bill Bowerman and Pete Starkey discuss process improvement strategies for the elimination of weak micro- via interfaces, and Bill's presentation at the IPC APEX EXPO 2021 Technical Conference. Best Practices for Metallization of Complex HDI Panels Pete Starkey Interviews Bill Bowerman From MacDermid Alpha Electronics Solutions