Hi Arjun,

It seems that the amount of flux deposited or the evenness across the
board, is likely to be the causes for the solder-short as you have mentioned
that it is better with the foam fluxer. 

Try using fax paper and paste it on a glass slide or wave-level gauge, 
allow the waxy side of the fax paper to face against the spray. Turn off the
preheat & the wave and pass the glass thru' the machine. Check the uniformity 
and also the coverage. It may due to the spray-fluxer stops spraying slightly
earlier before the board is completely travelled thru' the spray-head or 
uneven application on the board.

The solder balls formation  may due to insufficient pre-heat, or improper
wave-hgt adjustment..

Good Luck ..

Poh 

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At 02:45 PM 7/11/97, [log in to unmask] wrote:
>
>     
>
>
>
>     Hello Fellow Internetters,
>     I work for ERG telecommunications, in Perth, Australia.
>     We have been seeing problems  with the wave solder process,with two 
>     defect types ie. Bridging (approx 12%) and solder balling(Approx 2%). 
>     Bridging has the higher rate of the two problems.
>     The location that the bridging problem occurs is mainly at the front 
>     of the boards as they pass the wave machine.  Also bridging is mainly 
>     the trailing edge type but, there are instances when it bridges 
>     across the board.. 
>     The machine that is used, has the capability of spray and foam 
>     fluxing. Alternating between these two fluxing types, I observed that 
>     the foam fluxing gives better results, in most cases at 0% defect 
>     rate. My concern with changing to foam fluxing is that the residual 
>     contamination left after such a process is high( i am yet to test some 
>     boards with a Ionic contamination tester). The flux that is used is 
>     halide free Multicore X32-10i. 
>     
>     Does anyone have any suggestions to reduce such wave solder problems ?
>     
>     Regards
>     Arjun Murthy 
>     
>     [log in to unmask]
>
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