We are currently experiencing random grainular solder joints on double
sided rigid PWB assemblies after wave solder. Our wave solder machine is an
Electrovert Econopak 229, and we are using Alpha 615-25 (RMA-type) flux
with Sn6337 solder per QQ-S-571. The PWB is GHN type per Mil-P-13949/5 with
"C" type copper, and solder coated, with a dry film soldermask. We have
made many process adjustments, including speed, top-side board temperature,
wave bath temperature, etc. We have very recently verified that solder
purity is within specifications. The graininess we are seeing in the solder
joint (including the fillet area) is randomly distributed, and in some
cases located one pad from a perfect solder joint. There is no consistent
pattern from board to board. Can anyone offer some advice?

Bill Bromley/Mike Polifrone
Lucas Aerospace PSA
777 Lena Dr.
Aurora OH 44202 USA
voice: 216-995-1000 ex 7036
email: [log in to unmask]



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