Charlie,
Experienced problems thermally cured masks with uncured or uncross-linked 
soldermask where soldermask exhibited solder webbing, solder balls embedded 
in the mask, crazing from proximity of solder iron heat where the medium is 
the flux. Also the aqueous OA flux when washed turns the surface of the mask 
to a white translucent haze or streaks. This lightening or discoloration of 
the mask can be tested by dropping methylene chloride on the surface for 1 
minute then wiping with swab and with fingernail scratch the pcb and look 
for removal of the mask as residue on swab or in the finger nail. This 
indicates that the mask permanancy properties should be analyzed.
BW 




I would like to know if there is any affect on the solder mask of a pcb 
after it goes through the wave solder operation.  Does the mask "soften"? 
Would it become "sticky"?  Could it pick up impurities from the wash process 
because the properties of the mask have changed?  I would appreciate any 
answers to these questions.  Thanks.  Charlie
     
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