I think your preheat is too high. You need preheat temp before solder pot
about 230F on TOP side. You may be burning of the flux rather than allowing
it to activate.

Check it out.

re,
ken patel

At 10:38 AM 10/15/97 -0400, Blanchet,Richard wrote:
>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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______________________________________________________
Ken Patel                       Phone:  (408) 490-6804
575 Cottonwood Dr.              Fax:    (408) 490-6859
Milpitas, CA 95035              Beeper: (888) 769-1808

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