I want to evaluate the possibility of converting to a 100% tin electroplate finish on PCBs that requires a tin or tin-lead for contact pads. Primarily 72 pin SIMM memory modules which are destined for use in tin or tin-lead (usually high tin content 90/10 - 95/5 tin-lead alloy). Overall thickness is an issue with SIMM products (.050" + .004" -.003"). The HAL process results in a adequate finish most of the time, however this process can not be tightly controlled and is a root cause for thickness rejects and contact rel problems. I've a couple of goals: 1) Improve quality and performance of our product by improving contact reliability. 2) Give our PCB suppliers a way to improve yields for overall thickness. There are other pluses (for us and the PCB suppliers) associated with a conversion to tin that I won't bring up. I'm primarily concerned with overcoming any potential quality or reliability problems. Here are some of my concerns: 1) Tin whisker growth. Dependent on stress induced during electroplating. Low/no stress plating is critical. Whisker growth begins at ~50 'C. Spacing between contact pads on a 72 pin SIMM is .010" so whisker growth has to be eliminated. Whiskering is not a problem with lead present. Test conditions: High temperature storage, 150 'C unbiased. Length ? 1080 hrs 125 'C high temp operating life, biased. 85/85 APB T&H 2) Tin undercut must be minimized to prevent tin slivers. 3) Solderability, tin-oxides form readily at room temperature. This problem exists with HAL, but to a lesser same extent. 4) Copper-tin intermetallic growth, tin should be a minimum of 200 microinches thick. Again, this problem exists with HAL. Test conditions: Same as in #1. ************************************************************ My question is, has anyone experience with a tin electroplate finish in a similar application? Any potential problems I've overlooked? All comments are appreciated. Thanks in advance. Tracy Tennant ([log in to unmask]) ph (208) 368-5963