Re: Homemade PCBs!

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

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