Several years ago there was an article that said anytime you "solder sculpt" a 
connection, you degrade the integrity of the pwb by 80%. I believe it had 
something to do with trapped moisture and the cosmetics of the joint without 
preheating could cause outgassing. Going back farther than IPC-A-610, Mil Std 
454 Req 5 also dealt with the acceptability of a partially filled connection.

______________________________ Reply Separator _________________________________
Subject: Through Hole wave Vs. rework
Author:  [log in to unmask] at SMTPpost1
Date:    10/10/96 4:46 PM


     
     We are building a board that has 8 layers with multiple ground planes, this
     
     combined with Entek plus coating and a no clean process is making it 
     difficult to optimize the wave solder profile to get 100% fill with a 
     fillet on all pins on the top side of the board.
     
     The IPC A-610 rev B specification calls out 75% fill as being acceptable 
     (table 4-1, pg. 52) on through hole solder joints. We are pushing our 
     subcontractors to get 100% fill with a fillet on each pin.
     
     Since we are setting our expectations to 100% fill on these solder joints 
     the subcontractor is having to touch up some of the solder joints to meet 
     this requirement (they are touching up the pin from the solder side letting
     
     the solder flow through the board to the top)    Thus my question...
     
     Is a solder joint that is 75% filled over the wave stronger (more reliable)
     
     than a solder joint that has been touched up to get to 100% with a fillet? 
     
     What is the effect to long term reliability of touching up a through hole 
     solder joint?
     
     I would really like some reference material on this subject if anyone has a
     
     source.
     
     Thanks,
     
     Mark Weiler
     [log in to unmask]
     512-728-8323
     
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