Hi , We are using water wash solder paste to solder the SMT LED's manufactured by Chicago Miniature lamp (CMD93-21 & 22)and Kingbright. Achieving the solder fillet , wetting has no issue but we observe high fallout at the functional testing. If we do some touch up on the LED's leads the the LED pass the test. We are controlling the LED's storage and handling conditions recommended by the manufacturer. Note the the LED's are solderd on the ENIA(Electroless Ni/Immersion Gold) pads finish.