You could try baking the board before it is wave soldered.  Put the board 
through the wave solder process while it is still hot.  You could increase your 
flux content in the plated through hole (barrels) by increasing the pitch or the
pump pressure for the sprays.  If you are using a no-clean/low-residue, even 
though the base alcohol or water has dried, the flux solids should still be on 
the surface.  What speed are you running through the machine?  Pre-baking this 
CCA may help the most.  Around 200 degrees "F" long enough to heat up the CCA.  
Careful not to bake to long and degrade your solderability.

______________________________ Reply Separator _________________________________
Subject: ASSM:  Top fillet formation
Author:  [log in to unmask] at INTERNET
Date:    12/20/96 6:58 AM


Hello Technetters,
     
I need some advises. I have a  6- layers board. I try to wave solder it, 
the solder 
at the ground point is not able to flow up to the top side of the board, in 
fact, it
doesn't flow above 75%.
     
We have tried using a solder-iron and set to temperature to 450 deg. cel. and 
hopefully able to force the solder through the PTH. Too bad, it didn't work 
anyway
and it in fact has caused some lifted pads.
     
We use full blow Nitrogeneous wave-solder machine, and the flux we use is 
only 1.2% solid content. And if the preheat temperature set to high, the flux 
gets degraded before it even reaches the wave..
     
I would like to know if anyone could advise me how wave-solder such a board 
with a great heavy thermal mass.
     
Thanks in Advance..
     
     
     
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