I'd offer one other suggestion. We've always been told that the OSP coating thickness cannot exceed 0.5 um, but we've seen instances where it greatly exceeds this value - up to 3x in some situations. The OSP suppliers have argued that this was impossible, but the data did come from a very reputable lab and I don't doubt the results. The difference (in my opinion) comes from the analytical method. The OSP suppliers measure thickness on copper coupons by chemically reducing the coating and calculating an average for the entire coupon. (At least, this was how they did this 3-4 years ago when we had this discussion!) The significantly thicker coatings were found in localized regions, such as on BGA SMT pads. The pad geometries, coupled with surface tension of the coatings, may have contributed to the thicker readings. Greg Bartlett Mercury Computer Systems Chelmsford, MA [log in to unmask] > > Hello Technetters, > A colleague and I have been facing some problems in Circuit testing > with 2 types of boards that have OSP coating. There has been a low > First time pass yield at approx 40% due to the thickness of the OSP > coating, which we are specifying to the PCB manufacturers to be in the > range of 0.2-0.25 um. > The OSP coating is Entek Plus type 106 and the type of pin material > used on these OSP boards are High conductivity steel made by QA > technologies. > The Incircuit tester used is HP 3070 series II with vaccum fixturing > and the total pin count is 2004 pins on one board type and 1443 on > another. Test time is approximately 1-2 minutes per board, and the > failure if faused by poor pin contact will occur within the first 30 > seconds of testing. > We have been trying some alternative pin types ie. rotating flux > buster type pins. Has any one out there used this pin type or any > other that has increased the success rate on the FTPY? > Does anyone have any suggestions on > - alternative pin types and manufacturers > - changes to the test fixturing to help resolve this problem > - information on how to ensure while manufacturing these boards, osp > coating proceses are controlled to get the right coating thickness. > > Thanks and regards > Arjunan Murthy > [log in to unmask] >