Hello Bill,

I have the same issue before. I guess you can try lower the soldering pot
temperature and increase the conveyer speed. What is really going is that 
the board is holding on too much heat. And it takes rather "long time" for 
the solder to solidify, and resulted in grainy solder joint - (some sort of
slow 
rate of crystallisation).

Are your board have lot of DIP IC, and huge thermal mass. ??? 

Another suggestion, try installing a fan/blower, near to the exit point of
the 
solder pot, (but not too near as it might create solder short) as to increase
the rate of solder solidification.

Good Luck !!!!!!!!

Poh

............................................................................
...........................................................................





At 04:05 PM 3/18/97 EST, you wrote:
>
>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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