How are you masking the holes that do not get soldered. I've seen this with 
uncured spot mask sealing pads that do not get soldered in the wave.

I've also gotten top side solderballs on an electrovert with the omega bar set 
too high (at a previous employer).

E-mail me or post more specifics and I can provide more specifics.

Aric

______________________________ Reply Separator _________________________________
Subject: Solder Balls
Author:  [log in to unmask] at INTERNET
Date:    6/30/97 10:23 AM


     Good morning everyone,
     Lately, we are experiencing solder balls on the top side of single 
     side PWB.  There are some holes that do not get any components before 
     wave solder.  When the board hits wave, it makes "frying" noise and 
     next thing you see is solder balls.  There are two bottom pre-heaters 
     set at 450 F & 475 F.  Solder temp is 500 F.  Conveyor speed is  6 
     fpm.
     
     This problem occurred in the past and was solved by increasing 
     pre-heat temps.  which were originally 325 F & 350 F.  Now we are at 
     the peak of  highest component heat ratings.  I checked several boards 
     and made sure that there is no flux left on the bottom side before it 
     hits solder wave. 
     
     Any suggestion on what should I try next will help.
     
     Thanks in advance,
     Paresh Patel
     Oneac Corp.
     (847)816-6000 X-704

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