Phil wrote:
> I've often wondered why not use a cnc machine to cut a paste stencil?
> Bascially, its just a couple mil thick piece of plastic sheeting that
> you squeegee (sp?) the solder paste over. A stencil is pretty easy to
> use - I watched a guy prep a board for reflow in about 5 minutes with one.
Stencils are really a production assembly tool used
where volumes of boards are being produced. The
amount of solder paste waste/contamination otherwise
is excessively high.
For contemporary solder paste formulations, once the
paste is brought to room temperature and handled in a
stencil screening process the shelf life is drastically
reduced. With the cost of solder paste in prototype
quantities somewhere between $25-40 per 250gm a more
conservative approach is quite attractive.
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uhmgawa@... www.gnu.org