Re: Home-made SSI chips

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While I admire your enthusiasm, it is highly unlikely that you can
build, even low resolution, integrated circuits without a fairly
large capital investment (probably a minimum of tens, if no hundreds,
of thousands of dollars). The process requires a number of steps, each
of which reqires specialized equipment, high purity (possibly poisonous)
materials and a high degree of accuracy and precision.

Here is a web page that gives a quick overview of the IC manufacturing
process: http://rel.intersil.com/docs/lexicon/manufacture.html

If you would like an interesting and challenging next step in your
hobby, you could either 1) try making multi-layer circuit boards, or
2) start working with FPGAs.

Multi-layer circuit boards will move you a step closer to the IC
manufacture process (ICs require several layers to be built up on a
silicon wafer: at least, for PNP type devices, a P-type substrate, a
set of N-type regions in the substrate, another set of P-type regions
in the N-type regions, an insulating layer on top of the entire thing
and, finally, a metal interconnect layer between PNP devices).

FPGAs give you the chance to construct actual chips that can compete
with relatively modern custom devices (you can get, with carefull
design, devices operating in the tens of megahertz). While this has
little to do with the physical challenges of building ICs, it gives
you the chance to experience some of the logical design challenges.

Re: Home-made SSI chips
On 29 Sep 2003 06:52:49 -0700, snipped-for-privacy@bellatlantic.net (Jeffrey Dutky)

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Interesting :) So you say that I'm now a step closer to manufacturing
my own IC's ? Cool :) Just kidding, but seriousely, I builld
multilayer PCB's at home on a regular basis using my homebrew through
hole plating machine.

Markus

Re: Home-made SSI chips
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Don't tease :) Tell us more?

Mike Harding


Re: Home-made SSI chips
On Tue, 30 Sep 2003 07:08:58 +1000, Mike Harding

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Ok, you asked for it :)

A while ago, I put a little quick hack kind of homepage online showing
the station. I should update the pages to show the latest
developements. Time did not permitted this yet, but it's still better
than nothing.

www.myhome.ch/mzingg/pcbstuff/tps

A through plating machine is what you primarely need to create
multilayer boards. It's of course also a great thing to have for
double layers if you have lot's of holes and vias as it's often the
case. The process of creating multilayers then (somewhat
oversimplified to be short) boils down to first creating the inner
layer but withouth any drilling, then glueing the outer layers onto
the inner layer, drilling and through hole plate the whole stack. Then
expose and etch the outer layers, apply a solder stop laminate if
requiered. The process is the same for 6 layers but of course takes
another aditional glue etc. step. Drilling is always done as the last
step after glueing layers. You will need to work with photoresist
laminates cause through plating on precoated material is not possible
- and - the holes must be covered during the final etching stage of
the outer most layers or else the through hole plating will be etched
away. Actually, using photoresist laminates is fun and fairly easy
once you know how to do it. A nice side effect of the laminates is
that you can create even finer artwork with them. The quality and look
and feel of the resulting PCB can't be distinguished from those made
in a board house if things are done propperly and provided you also
laminate a solder stop mask onto the final PCB. I use those homebrew
PCB's primarly for prototypes cause this is a huge timesaver and -
provided you have some reasonably anual volume of boards you need -
actually also the cheapest way to get (multilayer) PCB's (as a rough
estimate, calculate ~$1.5 per square inch). A four layer pcb takes
aproximately 5 hours until it's ready. The speed is influenced by the
fact wether you have a CNC drill or not ( I don't). Having one will
speed up things by ~1 hour. This is of course a rough estimation for
PCB's that are reasonably sized (i.e. 4x6.5").

Btw, building a simple CNC drill is my next project that I will start
as soon as time permits. I mostly want one to reduce the risk of
creating an unuseable PCB by a drill error after 3 hours of work and -
of course - it's also not so funny to hand drill > 200 holes.

Markus


Re: Home-made SSI chips
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I am impressed sir. And after reading you more detailed account of
multi-layer circuit board production, I think you may be a lot closer
to building ICs than at first appeared. You still need to deal with
the caustic/ultrapure/high-temperature chemical problem, but you
probably have the other problems licked (I'm not sure how similar
the photoresist you are using is to what is required for IC manufacture,
but you are certainly on the right track).

The alignment and optics should be too big a problem: you should be able
to use standard photographic equipment for the optics, and the alignment
is just a matter of patience (especially if you are willing to ruin a
high proportion of your wafers).

The checmical problems (obtaining silicon wafers and the oven in which
to bake them to produce doped and insulating layers) are just a slight
matter of money. I'd bet you could find some nice, bench-top, top stuff
in any scientific supply catalog. I'm pretty sure the oven needs to be
able to sustain a vaccuum, so no simple consumer device will substitute.

Another problem would be disposal of the byproducts: these things are
TOXIC and probably tightly regulated by your local government. It's bad
enough if you just want to do photography or auto repair.

-- Jeff Dutky

Re: Home-made SSI chips
Hi Jeffrey

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And I'm more than surprized to hear this. I never would have spend one
single thought in producing home brew IC's and I'm sure I'm not going
to try this in the forseable future. I'm really happy for the moment
to have found a way to produce multilayer PCB's "at will" cause this
is a huge time and money saver. Also I'd like to point out that I do
this exclusively to produce prototypes.

Thanks for your information anyways and who knows, maybe you have just
placed a virus in my brain :)

Markus

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