Hi, We have been struggling with an issue of non wetting on a QFP (Renesas - 256, Sn90Pb10) but the issue "desapears" sometimes for a while and then back again suddenly. This is the scenario:
Component: QFP 256 / Renesas / Sn90Pb10 / 0.5 mm pitch
Solder paste: Indium NC-SMQ92J Sn63Pb37 / Proflow Cassette
Profile Used: Ramp To Spike - N2 environment.
PCB: HASL finish, 3 ounces copper.
Same component is placed in a different PCB without having this issue, both PCBs are from the same MFG house and both HASL but the other is 2 Oz copper, Both assys run on the same line.
We have been playin with reflow profile on peak temperature, TAL, initial ramp with no success. recently I plotted Defects related to this specific issue with average temperature and relative humidity and there's an evident defect increase when RH increases. Have you seen a sumilar issue before? or how can I contain the it.
thanks in advance!
Ps. Attached are an image of solder profile and defect plot
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