[sdiy] DIY pcbs - how difficult is it, and where to begin? (sorry, it's a bit long - make a cup of tea first)

[Steve Lenham]

Hi Julian,

Have been meaning to reply to this, esp. as not many others have.

I make some of my own boards, both for my own use and as commercial 
prototypes. Because I don't really enjoy doing so (it's dirty, smelly and 
time-consuming), I only do it when there is a good reason. That reason is 
usually that I only need one or two boards, and even the best commercial 
boardmakers aren't very cost-effective at that volume. Any more (even if you 
might only need the extras in the future) and I'd recommend getting them 
commercially done. Another good reason might be that you need/want the 
boards NOW rather than next week (or whatever).

I also wouldn't entertain making anything other than single-sided boards. 
Yes, it is possible to do double-sided at home but you need to work very 
hard to get it right and, even if you get the layer alignment right, you'll 
miss the plated-through holes terribly.

If you're still up for it, the good news is that there is no black art 
involved and I can recommend a simple system which has consistently 
delivered me very good results (and everything comes from Rapid). The method 
I use is optimised for speed and cleanliness and might not be the choice for 
higher volumes - but IMHO you shouldn't be DIYing large volumes anyway...

1. Artwork

Buy the blue Press-and-Peel sheets (Rapid 34-4450) and laser-print the 
artwork onto them. Obviously it helps if you own a laser printer - 
photocopying is also supposed to be possible but I've not tried it. If you 
have laid the board out yourself, you can print stright from the layout 
software. Ditto if you have a PDF of someone else's layout. Paper artwork 
can be scanned in, with the advantage that old magazine plots can be cleaned 
up on the computer before printing. The only thing to watch out for is 
slight scaling errors in the scanning (do a trial run on paper first), but 
quite acceptable results are possible - I did the old ETI phaser board that 
way.

The printed artwork is then ironed onto bare copper-clad board using a 
clothes iron. Some people have reported that this is a tricky process but I 
can honestly say that I have never had a problem or an unusable board. The 
critical thing is preparation of the board material. It needs to be really 
clean and really smooth. First get rid of any hint of a burr along the board 
edge with a fine file (even a small burr will hold the artwork away from the 
copper and prevent it adhering properly at the edges). I then use fine wire 
wool to scrub off the oxide layer and make the copper really bright, wash 
the board with a bit of washing-up liquid on some kitchen roll (as you can 
see I use only the most exotic of materials ;-) , rinse it with tap water 
and dry it off.

For the ironing, just follow the instructions which come with the sheets. I 
did so, with no previous experience, and even my first board turned out 
fine. They specify a range of times for applying heat - use the longest for 
large boards and reduce it for smaller ones. It is better to iron for 
slightly too long than too little time - overdoing it just causes the toner 
to blur somewhat, but the board is very likely to still be usable.The heat 
of my iron just goes from 0 to 5 - I use 4. When done, cool the board with 
cold water and peel off the backing sheet - the toner of the artwork should 
be stuck to the board.

This method is good for quite fine artwork - it has no problems with tracks 
passing between the pins of standard through-hole ICs.

2. Etching

Buy the Seno etch-in-a-bag system (Rapid 34-0384). Yes, it's more expensive 
than mixing up your own etchant in a pot but it keeps you as far away from 
the horrid ferric chloride as possible. You only need to ruin one pair of 
trousers by getting etchant on them and the financial advantage of making 
that board yourself will be but a distant memory.

Again, just follow the instructions, which pretty much amount to putting the 
board in the bag and swishing it around a bit. You can watch the board 
through the clear bag and see for yourself when it is fully etched. You then 
take it out through an "airlock" which keeps you separated from the etchant 
as much as possible, and rinse off the board (preferably at the outside 
tap - there will be a tiny bit of etchant still present).

The toner can then be removed from the copper with wirewool.

3. Drilling

You need a little handheld electric drill (Minicraft, Dremel, etc. - still 
all from Rapid) and a small selection of fine bits (0.8mm, 1.0mm and 1.2mm 
will get you a long way). A drill stand would be great, and saves the odd 
broken drill, but is by no means essential (I haven't got one yet).

Some may hold up their hands in horror, but I only use SRBP (paper) board 
material for my DIY PCBs because it is SO much easier and quicker to drill. 
It also spares you the foul-smelling and rather unhealthy fibreglass dust 
which drilling conventional material generates. Even so, it's still nice to 
rig up your vacuum cleaner to suck up the dust as it is created.

That's about it! Excluding the drill, you are looking at expenditure of 
about £30 for the artwork sheets, the Seno etch kit and some board material. 
Why not give it a go? Let me know if you need any more tips.

Sorry for the ramble - layout software, layout technique and commercial 
board manufacturers will have to wait for another day!

Cheers,

Steve L.

----- Original Message ----- 
From: "Julian" <julian at 22host24.com>
To: <synth-diy at dropmix.xs4all.nl>
Sent: Thursday, January 05, 2006 1:31 PM
Subject: [sdiy] DIY pcbs - how difficult is it, and where to begin?


Right, Its something ive wondered about for a long time, but never made a
start with, so im wondering -  etching your own board: how much of a black
art is it?

How many attempts is it likely to take before i get it right (i know thats
an open ended question, but, is it like 'wow - he got it to work first
time - amazing!' or what?)

I have a friend who tried twice in the past, with no success, i suspect that
they were reasonably carefull, so thats what worries me ; )

Is there some fool proof technique?  Im guessing that the variables of
temperature, time, and chemical makeup all affect things, so im wondering if
i can get a specific set of one make of chemicals / boards and just follow
the directions to the letter - ie to take out any human skill on my behalf.

I know some of you make boards all the time, but, as i say, im aware my
friend had no success, so it cant be that easy either.

Any comments at all would be most appreciated.

Again, im in England, so any suggested products need to be available here
too.


Failing all that, if i want to get a company to do it for me...

To go from the schematic to pcb, i need to do the layout in some program
(any free and easy suggestions?) and upload the file to a company (i know
there have been threads in the past on companies), but, having never used
the layout software, im wondering how automated it all is?  Ie. is there
stuff i need to *know* about board layout rather then just being careful
with inputting data off schematic?  (Will i have decisions to make)

Basically, id like to start on this, whichever way, but id really like some
pointers as to where to begin.

Cheers, Julian