I would be more inclined to suspect the solder mask thickness.  Thicker
mask would hold the stencil futher away from the pad and leave more paste.

Regards,
Ken Kirby





 (Embedded
 image moved   Rob Watson <[log in to unmask]>
 to file:      05/17/99 02:18 PM
 pic18212.pcx)




To:   [log in to unmask]
cc:    (bcc: Kenneth Kirby/ElectrovertUS/Cookson)
Subject:  Re: [TN] Different Paste Height




Are these boards HASL?  You may want to look to see if the coating is
thicker on the one board.  Without
knowing anything else that is the only thing I can think of at the moment
which would cause a difference..

Hope this helps,
Rob Watson
Sanmina Corp.


Poh Kong Hui wrote:

> Hi,
>
> Have anyone encountered that PCB from different suppliers give different
> paste height.
>
> We are using 3 PCB suppliers for one of our product, and the average
paste
> height we are getting (on 2 suppliers), using 6 mil stencil with rubber
> squeegee (70 durometer) gives an average paste height of 6.5 mil.
However,
> there is one supplier's PCB that gives the average paste of 8 mil.
>
> We need to double the squeegee pressure to achieve the paste height of
near
> 7.0 mil
>
> Could anyone advise me the cause to such issue.
>
> Thanks
>
> Poh
>
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