>      
>      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

At first, what is the problem at wave soldering, why can't you get 100%
fill? How much heat do you have on the PCB? How long dwell time do you
have at soldering? What kind of flux do you use?
We have alot of 8 layer pcb with multiple ground planes and get great
results, but then ofcourse we sure do have problems sometimes.
To my knowledge it's a minimum of 75% fill, but between 75%-100% makes
no different, it's just as stabile at 75% as it's is at 100% and
touching a through-hole soldering joint only makes it better and no harm
as long as you don't do anything wrong.
This is my view of the situation, please tell me if i'm wrong.

Jan Merstrand
Ericsson Microwave Systems AB
 

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