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FrozenGate by Avery

DIY circuit boards?

GooeyGus

GooeyGus

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So I'm interested in building my own drivers using printed circuit boards... but I really know nothing about building the board itself. Can anyone give me the basics or point me in the right direction?
 





There's a lot to it.
First you design the board.
Then you need to get the photocoated board.
Then you need to print your design onto acetate.
Then you expose the PCB to UV light with the design laid over it.
Then you dip it in photo developer which washes away the exposed photocoating.
Then you dip it in acid which eats away the exposed copper, leaving the coated tracks.
Then you just rinse it in water to remove the coating from the tracks, then you drill it and all.

All in all it's a tricky process and not one that goes right first time. There's a lot of experimenting to find out what works for you, and unless you have a large mercury vapour bulb in the shed (like me :P ) exposing can take a long time.
There's also a lot of nasty corrosive chemicals.

That said it can be done and often is. Though if you don't want the bother, I'm more than happy to print one or two boards for a small charge. :)
 
It is quite a lot to set up if you only plan to do a couple of boards really. I've done many in the past, but dont have a setup at home here. I guess its a bit like setting up a complete darkroom to develop 2 films of holiday shots a year - might be better to get someone else to do it.

That said, if you're interested and have some space and time to experiment, it's well possible to make your own pcb's.

As for exposing the pcb: I've had excellent results using the tube lights that come out of face tanners. Those emit a good level of near uv, which works well on pcb photoresist and exposes them in a few minutes.

Printing the layout can be done with a laser printer on 'milk paper', which is semi transparant but passes enough light to work. Obviously this should be done as a mirror image in order to get the printed tracks close to the PCB. We used a vacuform-like device to make a tight connection between print and board - but i guess it can be done with just a frame, some pressure and luck.


I've also heard people have decent results by printing the tracks onto glossy (photo) paper using a laserprinter, and then transferring the toner directly onto the (non-photosensitive) pcb using a clothes iron. The toner sticks to the copper and the paper can be removed after soaking it in water for some time. I havent tried myself, but heard it works well as long as you dont need really fine (smd ic's) tracks.
 
The laser printer method works very well actually. The difficulty lies in finding the right photo paper as not all photo papers are the same. It is recommended that the paper be for an inkjet even though it is run through a laser printer. Prep the board, removing all oils and dirt and brush it up a bit then iron on your custom transfer. Soak in water to remove the paper. There's quite a bit of information on the internet about this process. You can buy paper specifically designed for toner transfer. It's like $15.00 per 10 sheets. Here's a link to a site that describes the process: http://www.headwize.com/projects/garbz2_prj.php .
 
yep, toner transfer for the win. No exposing, only a laminating press or iron is needed. This is how I and several others can build boards even using sub-millimeter pin spacing packages, with a turnaround of 1 day.
 
I tried the toner transfer method, and it works perfectly. But i don't use photo paper.

I use printable labels, throw the labels away, and only use the waxy label backing sheet.. After ironing, i only have to wait for it to cool down, and i can peel it off. Everything transfers perfectly without soaking in water. It is much faster this way..


Unfortunatelly, the ease with which it transfers is the result of the toner not sticking properly to the waxy sheet. It can happen, that it doesn't print evenly.

In this case, i simply use a credit card to scratch the label backing, and then wipe it with a paper towel. After that it prints perfectly, and still transfers without a problem.
 
That toner x-fer is pretty neat... maybe I'll try that. If not I may get a hold of one of you guys that make your own boards! thanks a bunch!!
 
K, I suppose someone should wade in here as the safety nazi.

Wear those great big mamma sized cleaning rubber gloves, and use some plastic tongs, and goggles, when you get to the etching stage. A white smock really completes the look.... and saves your clothes.

Toner transfer is cheap, even for someone without access to a laser printer. You can always make your design and take it to office depot and have them make you a couple of transfers for a few bucks.

Go grab a single sided or double sided board from radio shack.

Home Depot, or Lowes has the Muriatic acid, and Hydrogen Peroxide, if not, then walgreens has big jugs of H2O2.

2 parts H2O2, one part Muriatic acid, for the etching solution.

Iron on your design.

If you use a paper backed transfer sheet, getting the back slightly damp before peeling off the ironed on design helps.

You can touch up your transferred image (parts that didn't transfer well) with a sharpie.

Soak and stir occasionally about 20-30 mins. Plastic utensils. Tongs. Gloves. Goggles. A warm solution works faster than a cool one. Take your jugs and place them in a sink of hot water before you mix them in your plastic bin, and it'll speed it up a bit.

Another safety tip would be to keep all aluminum away from the solution...... This is a big one.

Rinse, Repeat.

After you are done, flush the solution down the TOILET. NOT YOUR SINK.. Sink pipes are copper, toilet pipes are plastic.


Rich
 
i use standard paper for toner transfer and it works like a charm. if you dont have a laser printer go to a 2nd hand shop i got one for 15$
 
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