We solder both mixed SMD (bottom side and leaded) and leaded panels 
     with large heat sinks and 15 relays with a 2% solids no clean in air, 
     some panels are 6+ layers. Hole filling is not a major problem, with 
     the exception of specific parts with hole/lead ratios outside of our 
     design standards. However, I can get 100% fill with a more aggressive 
     flux. 
     
     The chip wave is not required on one brand of machine. I must use it 
     on another, most likely because of a spray fluxer issue.


______________________________ Reply Separator _________________________________
Subject: RE: ASSM:  Top fillet formation
Author:  [log in to unmask] at internet
Date:    12/21/96 2:41 AM


A couple of questions,
     
1.   Are you using the turbulent wave with the lambda wave?
     
The added thermal transfer that the turbulent wave will add to the card may 
help improve your solder filling problem.
     
2.   What temperature is the topside of the board at before contact with the 
solder wave(s)?
     
Going somewhat hotter then your flux manufacturers recommended temperatures 
in not always a bad thing.  I would think it would be better to run hotter 
and get some solder up in the barrel then to run cooler and not have solder 
fill.  As long as components are not being damaged.
     
3.   What type of fluxing application are you using? foam/spray
     
Foam may give you a little more flux up into the barrels.
     
     
 ----------
From: TechNet-request
To: Technet
Subject: ASSM:  Top fillet formation 
Date: Friday, December 20, 1996 06:34
     
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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