RE: Exorcisor on a chip

> Maybe I'm not follow this discussion, but let me ask. By using
> several
> connectors and a 7414 at the corners of the boards (resulting in a
> single layer board), does that make this PCB cheaper to produce?
>
> The obvious answer is "Yes, Steve."
>
Yes, in some production runs (depending on the boards material) but more
importantly it gives the "etch it yourself" crowd a much better chance
of success with the board.

> So my next question is, "Does this change also eliminate the need for
> drilling (or simplify the drilling to be just the pattern for
> socket/connectors/IC pads)?" I'm trying to understand if the new
> layout
> has made the PCB cheap enough that we'll have more demand for it or
> need
> less people to make a production run of it.
>
In this case you're probably offsetting any cost benefits of a single
layer board by taking up a lot more square inches. Not a big deal if
you just bought a 6"x9" PCB to etch yourself, but in production square
inches = $$$. If someone wants to mass produce it you're better off
with a 2-layer "as small as you can cram it into" design. If you're
going to sell 100,000 a month for $9.95 you'd want to look at
through-hold components on single-layer phenolic built in China...

> I guess I also don't understand how single layer boards affect
> cost/drilling? Maybe Al's implying that because the board is single
> layered that it is more easily etched by hand rather than created in a
> production run?
>
Single layer is cheaper than double layer in production because you will
generally use cheaper materials to make the PCB's. (Phenolic or treated
cardboard instead of FR4 fiberglass.) Drill time is (for small runs)
usually counted in drill hits, but depending on what/where you do things
it can be MORE expensive to have fewer holes over a large area vs. fewer
holes in a small area. (Time it takes to position the drill head.)
Changing drill bits more than a couple times per board is spendy too.

Someone can just layout a single-layer design, save it as a 300DPI TIFF
(or whatever) for 1:1 printing on a 300DPI laser printer and then anyone
can print it on transfer film and make their own PCB...

-Clay

> Steven S Ozdemir
> sso@plpt.com (my company renamed itself in Feb)
> sso@dsc.com (good for a few more months)
> ozdemir@xenon.stanford.edu (permanent...weekly)
>
> ps - If power and clock have to come through the center of the board,
> that implies some drilling.
>
>
>
> >----------
> >From: aek@plpt.com[SMTP:aek@plpt.com]
> >Sent: Monday, February 23, 1998 8:47 PM
> >To: vectorlist@spies.com
> >Cc: aek@ns1.plpt.com
> >Subject: Re: Exorcisor on a chip
> >
> >I just sent a note to Joe that with a pin reassigment and placing the
> >3 sockets and the 7414 at each corner with the mach part in the
> center,
> >you can do the layout on a 1 layer board:
> >
> >+- -+ +- -+
> >J1 J3
> >
> > mach210
> >
> >
> >+- -+ +- -+
> >J2 pwr,gnd 7414
> >
> > pins
> >
> >the ground wraps around the outer edge of the board,
> >power and clocks go through the center..
> >
>
Received on Tue Feb 24 11:09:41 1998