nuckollsr(at)cox.net
Guest
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 Posted: Wed Jan 17, 2007 6:53 am Post subject: Hobbyist ECB services |
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At 09:51 PM 1/15/2007 -0500, you wrote:
| Quote: |
<eanderson(at)carolina.rr.com>
While I have been a satisfied customer of ExpressPCB for a number of years
and think they are indeed a great PCB provider, I have lately found some
of there limitations - well, rather limiting. I have decided to convert
my project design from through-hole to surface Mount (ugh! those
components are almost invisible!).
In order to keep my sanity, I decided that using a stencil to lay on the
bare board for a limited number of units would be an ideal way to
go. This stencil is simply a thin metal (or plastic) sheet with holes
very precisely cut to fit over those component pads you wish to have a
solder paste deposited on. So you put the paste on the stencil and use a
squeegee to pull the paste across all the holes in the stencil thereby
depositing the solder paste only where you are going to put a component.
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Gave up on solder paste in a skunk-werks environment.
The stuff has a shelf life and is not the friendliest
material compared to wire solder.
| Quote: | Then you use a magnifying glass and tweezers to put the tiny components
on their pads and pop them into an oven and voila (if everything goes
right) you have a solder surface mount board.
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We've settled on 1206 or larger components as the
smallest we'll use in a hand-assembled design. We
lay down a wire solder dot on one of the pads, then
slide the part into the hot pad with a tweezer. After
the part is tacked into place, we solder the free end.
The tack end occasionally needs touch-up but not often.
| Quote: | Now the problem is that ExpressPCB does not offer the stencil service,
furthermore most firms offering the stencil service require a set of
Gerber files (normal CAD output of most PC board software). You can not
directly produce one from the ExpressPCB software. You must pay an
additional $60 for a Gerber file from ExpressPCB. This is the file that
EAGLE and some of the other readily available PC board software produces
that file as a normal course. So $60 just seems a bit much when there are
package that produce it free.
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ExpressPCB was designed to support the
few-of-a-kind, hobbyist/skunk-werks market.
Our engineering overhead is $800/man-day
. . . turn-time is critical to achieving
low-cost proof of concept solutions.
In this venue, I've found their service
to be invaluable. On one occasion I was
able to order, stuff and test three different
board configurations in a 15-day window.
There may be others with similar services but
what they offer for $59 a pop is pretty attractive.
| Quote: | A PCB software package that produces such non-proprietary Gerber files
also give you a much greater range of service providers including all the
way to China (very nice prices if you can stand the transportation delay).
So I believe, as Bob pointed out - it all depends on what your needs are.
For one of a kind, or a few, ExpressPCB offers a valued service at a
reasonable price. Up to now, I have used no other. But, some of their
limitations in face of my current needs are causing me to reconsider.
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Once I've proven a design, others are most
welcome to repackage and/or modify the design
to suit their particular manufacturing requirements
and favorite materials.
For the guy who wants to build a one-of-a-kind
electro-whizzy for his project, I'll suggest that
ExpressPCB offers some attractive and practical
support.
Bob . . .
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