Re: Homemade PCBs!

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Hydrogen18" <hydrogen18-at-hydrogen18-dot-com> 

I'm going to try something soon...any tips on making a PCB insulated to
15000 volts?

Also on the subject of CNC routers...they can be made cheap. Search the web.
For prototyping purposes btw, you could use a drill press and a routing bit.

---Eric
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Sunday, April 25, 2004 5:00 PM
Subject: Re: Homemade PCBs!


 > Original poster: "Jim Lux" <jimlux-at-earthlink-dot-net>
 >
 > Having been through both approaches in a variety of environments, I have
the
 > following observations:
 > 1) If you have the room to make the boards (including exposures, etc.) and
 > do it often enough that your process skills remain fresh, there is a
certain
 > appeal to being able to zap out a board "on impulse".  Draw the circuit,
 > make the board, solder the parts, and be testing in a couple hours.  20
 > years ago I bought a big stat camera which can do 1:4 reductions just for
 > this sort of thing.  Too bad I don't make enough boards to keep the
 > chemicals and film fresh, much less my photographic skills.  The camera
 > sits, unused, in my garage.
 >
 > 2) The commercial products will almost always turn out better (unless
you're
 > a business where prototyping is part of the day to day work).  While
making
 > good quality two layer boards is fairly straightforward, drilling by hand
is
 > a pain, decent robotic drills are expensive (more than a kilobuck,
although
 > I'd love to hear about a cheaper one), and doing plated through holes is a
 > real pain.  Then there's the solder mask and silkscreen..
 >
 > 3) On a cost basis, they'll probably turn out about the same, within the
 > significance of the measurement.  More dollars invested up front (or time
 > scrounging equipment and materials) for home fab, but fairly low piece
 > costs.
 >
 > 4) Multilayer (4 or more) are not real feasible for home fabrication. It
can
 > be done, but process controls are tough. There's also the problem of
minimum
 > order quantities for things like prepreg.
 >
 > 5) A very attractive alternative for a lot of prototyping is the computer
 > controlled router approach.  It will do the traces, and do the holes.
Won't
 > do the plated through, but it's definitely a hot ticket for RF
prototyping.
 > A tad pricey (again, if someone knows of a decent (assembled) system for
 > under $1000 (exclusive of PC), I'd love to hear about it).
 >
 > 6) There are some interesting approaches I've seen commercially, but I
 > haven't seen in hobby applictions, although I think they'd be appropriate.
 > Things like the "multiwire" where it essentially "plots" a special
insulated
 > wire onto the substrate, or various stereolithographic schemes (like the
 > computer controlled glue gun things).  I've also seen systems (based on
the
 > same scheme they use for making custom vinyl signs) that cut copper foil
on
 > a backing, which is then "glued" to a substrate.  Peeling the unused
copper
 > away doesn't strike me as a lot of fun (like peeling rubylith!) but might
 > give good results.
 >
 >
 > ----- Original Message -----
 > From: "Tesla list" <tesla-at-pupman-dot-com>
 > To: <tesla-at-pupman-dot-com>
 > Sent: Saturday, April 24, 2004 6:55 PM
 > Subject: Re: Homemade PCBs!
 >
 >
 >  > Original poster: "Jim Mitchell" <Electrontube-at-sbcglobal-dot-net>
 >  >
 >  > Or for about the same price it costs to get all the materials and
things
 > to
 >  > do photo etching,  you can have 10, 3X5 soldermask and silkscreened
boards
 >  > for 65$....
 >  >
 >  > Regards - Jim Mitchell
 >  > ----- Original Message -----
 >  > From: "Tesla list" <tesla-at-pupman-dot-com>
 >  > To: <tesla-at-pupman-dot-com>
 >  > Sent: Saturday, April 24, 2004 8:53 PM
 >  > Subject: Re: Homemade PCBs!
 >  >
 >  >
 >  >  > Original poster: Matthew Smith <matt-at-kbc-dot-net.au>
 >  >  >
 >  >  > Eric ("Hydrogen18") writes:
 >  >  > >I'm looking to make some homemade PCB's for a voltage multiplier,
 > whats
 >  >  > >the best way to do this? I've seen those kits where you draw
 > everything,
 >  >  > >but that seems pretty tedious. Is their a better way to do it at
home?
 >  >  > >Also, what kind of circuit board do I want to buy? Thanks.
 >  >  >
 >  >  > Matthew replies:
 >  >  >
 >  >  > I use PCBs for all prototypes - they are NOT hard to make once you
get
 > the
 >  >  > hang of it. I use a simple photolithographic process with all
home-made
 >  >  > equipment.
 >  >  >
 >  >  > Note that a PCB will be more reliable and easier to trouble-shoot
than
 >  >  > prototypes using solderless breadboard or ratsnesting.
 >  >  >
 >  >  > Now that I've got my technique down to pat and have got the optimum
 >  >  > exposure times, etc., I can throw a board together in very little
 >  >  > time.  I'm even starting to use some SMD components now.
 >  >  >
 >  >  > Abbreviated steps are:
 >  >  > 1) Produce artwork on a transparency.  This could be hand-drawn or
 >  > produced
 >  >  > by CAD software such as Eagle <http://www.cadsoft.de>.
 >  >  > 2) Acquire PCB stock coated with positive photoresist.
 >  >  > 3) Cut stock to size if required.
 >  >  > 4) Contact print artwork onto PCB stock with UV source
 >  >  > 5) Develop board with sodium metasilicate solution (easier to use
than
 >  > NaOH).
 >  >  > 6) Wash board
 >  >  > 7) Etch with ammonium persulphate solution.  This is far nicer to
work
 >  > with
 >  >  > than ferric chloride.
 >  >  > 8) Wash board
 >  >  > 9) Drill (unless SMD ;-)
 >  >  > 10) When ready to solder, remove remaining photoresist with acetone.
 > (It
 >  >  > protects the board in the meantime)
 >  >  > 11) - optional - flux and tin traces or use humungously expensive
 > tinning
 >  >  > compound ;-)
 >  >  > 12) Assemble and solder
 >  >  > 13) Clean off flux residues
 >  >  > 14) Step back and admire your work :)
 >  >  >
 >  >  > Exposure, developing and etching can easily be done in under half an
 > hour.
 >  >  >
 >  >  > One very important tip that I received from a member of this list
 > (think
 >  > it
 >  >  > was Dan Mccauley) is: remember to put plenty of test points on your
 >  >  > artwork, especially if this is a prototype!
 >  >  >
 >  >  > Contact me off-list if you want to know any specifics, like how to
make
 > a
 >  >  > UV exposure unit, etc.
 >  >  >
 >  >  > Cheers
 >  >  >
 >  >  > M
 >  >  >
 >  >  > --
 >  >  > Matthew Smith
 >  >  > Kadina Business Consultancy
 >  >  > South Australia
 >  >  > http://www.kbc-dot-net.au
 >  >  >
 >  >