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April 1997

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From:
"ddhillma" <[log in to unmask]>
Date:
Thu, 24 Apr 97 17:12:46 cst
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     Hi Elizabeth -
     
     You might try investigating the compatibility of the soldermask and 
     the flux chemistry. I have found that the soldermask texture (i.e. 
     either shiny/smooth or matte/rough) and the specific flux interaction 
     is very important. The general industry trend is that shiny soldermask 
     will have more solderballs/bridging than matte soldermasks but I have 
     found that with certain flux chemistries I can use shiny soldermasks 
     with no solderball/bridging problems. Good Luck.
     
     
     Dave Hillman
     Rockwell Collins
     [log in to unmask]


______________________________ Reply Separator _________________________________
Subject: Solder bridging after wave solder
Author:  [log in to unmask] at ccmgw1
Date:    4/23/97 7:19 PM


Dear Technet,
I have a customer who is reporting bridging on the solder side of the board 
after wave soldering.  I have seen the boards, and they look quite messy, 
with solder sticking to the mask as well as between component leads and 
pads.  The mask itself is adhering nicely.  The mask is PC501 from Haven, 
with C101 hardener.  This was recently discontinued by MacDermid and picked 
up by Haven.  The flux is no clean, ENFLUX NCF-8660, and is under pressure 
with nitrogen.  The wave itself is at 500 degrees F, with preheats set to 
get the board to 210 to 220 degrees F when it hits the wave.  The same 
design board with LPI ran fine, so I do not suspect a problem in another 
area of the process.
     
No other customers are reporting this problem, and I am at a loss as to 
where to investigate further. The customer is not happy, and wants a 
resolution today!  If anyone has any insights, please let me know.
     
Thanks,
Elizabeth Falk
Process Engineer, Beaverbrook Circuits
     
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