On 23 Aug 98 at 17:28, Stephen R. Gregory wrote:

> snip snap
> .....there's no mask, I'll do a 5-mil thick stencil, still do the same
> width reduction, but lengthen the aperture on the toe and heel by
> around 5-10 mils or so, that gives me some volume back that I took
> getting a thinner stencil to reduce the bridging from no damn
> dams...the over printed solder will wick back into the main fillet
> during reflow, and where it counts too, back at the heel. I leave
> the apertures 1:1 for the rest of the 50 mil pitch stuff except for
> the J-leaded parts which I lengthen too, since they need a good deal
> of solder to form their fillets.

Steve, I just wanted to ask, do you use a special CAM software for
this over/undersize black magic or is it much manual work with
D-codes editing and transcoding instead of just pressing the
"undersize button"? The SW I know mostly allows just (semi-)automatic
oversize/undersize for all selected items for which value I ever
needs. (If you dont't like "product placement", reply off-line
please)

Which solder mask oversize do you prefer? (depends on solder mask
process, screen printing or photo) If I want dams between the pads,
then I should have as low mask oversize as possible. But then I get
often PCBs with misaligned solder mask ON the pads....

Thanks
Matthias
-----------------------------------------------
Matthias Mansfeld Elektronik
* Printed Circuit Board Design and Assembly
Am Langhoelzl 11, D-85540 Haar, GERMANY
Phone: +49-89-4620 0937, Fax: +49-89-4620 0938
E-Mail: [log in to unmask]
Internet: http://home.t-online.de/home/matthias.mansfeld

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