At 08:50 AM 12/17/01 +1100, Ian Wilson wrote:
>On 10:34 AM 17/12/2001 +1300, Wayne Trow said:
>>We have recently had problems with our smt placement machines and reflow
>>causing beading of the solder because of too much solder paste. I have been
>>asked to reduce the paste apertures by 5% on all smt components.

Let me guess that the one specifying "5%" was not taking the trouble to 
find out exactly what reduction was necessary. Paste mask expansions are 
specified as oversize from pads. Applying a percentage to them will produce 
results not having a clear relationship to pad sizes. I don't think that is 
what the assembler actually needs. Rather, he needs the mask openings to 
have a specific relationship to the pad sizes. I'd find out what that is 
and define the masks accordingly.


[EMAIL PROTECTED]
Abdulrahman Lomax
Easthampton, Massachusetts USA

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