Hello,

Problem: We have some gold plated pads (SMT components, solder side) that
won't solder at the wave. The temperature profile seems good (140 oC or 284
oF for the bottom side). We use the chip wave and smart wave to produce some
turbulence. After washing the boards with water (we use Alpha 651 water
soluble flux) we can easily hand solder the faulty pads, showing that if it
were a contamination, it went off during washing.

There should be 5 to 10 microinches of gold plated over 50 to 100
microinches of nickel on these pads. The solder temperature is 260 oC. The
problem is most often seen near the fingers that hold the board (heat sink
from the fingers?) but is also seen just about anywhere on this board.

Questions:
 - What can cause this ?  How do I prevent it ?
 - Is 260 oC (500 oF) the usual temperature used at the wave ?

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