All of the projects on this blog have been made using either pad-per-hole PERFBOARD (each hole has its own copper pad) or VEROBOARD (rows of holes share the same copper pad and are connected).

Building electronic projects with these boards is feasible, but demands a lot of care and attention because during the placement of the components because the connections between them have to be made as well. This is quite labor intensive and prone to mistakes.

With this technique, we take a copper clad board, cover the copper with the appropriate etch resistant traces and then etch the rest of the copper away, leaving only the copper under the traces.

Materials needed: copper clad board, acetone, HCL, H2O2, water, inverted pcb layout printed on the best glossy picture paper you can find.
Tools: saw, clothes iron, water boiler, plastic containers, plastic tweezers, steel wool (000), Sharpie or black marker for writing on CDs

STEP 1: preparation

Cut out the layout pcb and measure the size of copper board you will need. Saw it to size. Do not leave space around the pcb layout, cut it exactly to size or smaller.



Clean the copper board with the steel wool 000, don't be lazy, clean it well, it will save you time later. Once it's shiny and clean, remove all the dirt and scraped off residue with a cloth soaked in acetone.

STEP 2: ironing the layout on

Take the iron and remove all the water. Put it on 'Linen' (hottest you can go) and wait until it's hot. Put the paper on the pcb, hold it on one side so it does not slip. Now apply the iron to one side of the board while keeping the paper in place. Do not move for about 15 seconds. After this time, the paper will stick to the copper due to the heat.

Now gently go over the rest of the board and really iron it so as to remove air from underneath the paper. Then put your iron flat on the whole board and apply pressure for about 2 minutes. Then iron the board top to toe, left to right. Just iron the hell out of it and don't be afraid, the paper won't catch fire. Unplug the iron temporarily if it indicates it's overheating.

Put the kettle on, Polly! Boil some water for a cup of tea or three. In the meanwhile leave the iron on the board. The more heat the better the layout will stick.

Make the cup of tea and put the rest of the water in any container.



Leave it like this for about ten minutes. You might want to put some more water on to add to the soaking bath when it cools down.

Sit down, have you cup of tea and check out the updates on modman.blogdrive.com


STEP 3: Removing the paper

Soak it long enough and refill with plenty of boiling water.



After your cup, take the board out of the water. Try to peel off the paper gently. It might come off easily in its entirety or seem to do so:



Be careful, in this case it might be that the traces may come off with the paper, so be gentle and check what happens. The bigger the surface, to more risk of the trace coming off.

A safer technique is to start rubbing the center of the board with your thumbs. The paper will then come off layer by layer and if you applied enough heat the chances of damage are minimal. Keep on rubbing, don't be affraid. If the board goes dry, soak again then continue rubbing.



STEP 4: Touching up

It might be that some parts of the traces didn't stick well (not enough heat!) and come off while removing the paper. If this happens you can touch up these areas with a black sharpie or cd marker. If you're saying now "Why do we need the layout on picture paper then?" my answer will be: it's faster then drawing the layout on with a sharpie completely. But it could be done. I would suggest that draw the layout, and when the ink has dried go over it again. This will give better traces.




STEP 5: Etching

BE SAFE -- please wear at least industrial rubber gloves and do this in a well ventilated area or outside.
Don't bring any metal in contact with the etchant, it eats metal.
Use only plastic containers and tools.

For 1L of etchant you need:

750ml H2O water
200ml HCL hydrochloric acid http://en.wikipedia.org/wiki/Hydrochloric_acid
50ml H2O2 hydrogen peroxide http://en.wikipedia.org/wiki/H2O2

Put some of this mixture in a plastic container that you put in another plastic container containing hot water. This hot water will accelerate the process of etching. Stirring the etchant CAREFULLY also helps. Don't breath the fumes, stand away if you're not stirring or checking how it goes.

It takes some time, dependent on the size of the board. Be patient and watch.



If you see traces only, check carefully whether there is no coper left between them,stir a bit more. If it's done, take it out with the plastic tweezers and rinse well with plenty of water. Leave to dry. The traces are still black, that the toner still sticking on the copper.



You can see the touch up has worked, bottom left corner in blue. I used a blue marker, it's not the color that does it.




STEP 6: Finishing the board

When dry, clean the board with steelwool 000. Don't be affraid, it's impossible to rub off the traces.



If you are not going to solder the board in the near future, don't remove the black tracing until you do. The toner coating will prevent the copper traces from oxidation and resultant corrosion.

In order to be able to place the components on the board, the boards needs some drilling. I tried hard with 1mm bits, but broke the 3 I bought because the drill itself was too heavy and the bits bent. You would be better of with a hand drill and a bit smaller than 1mm if you can find it. Another option is to use a dremel -- the 0.8mm engraving bit is perfect for the job. Apply the point of the dremel while resting your hand and holding at 45° as if you were writing. This way it easier to keep it steady while making the first contact with the board. Once you have a small hole, put the dremel straight and drill through.

CONCLUSION:

1/ You really don't need that expensive Press 'n Peel Blue dedicated pcb transfer. You even don't need to have Staples Picture Paper, though it appears to be a very good photo paper.
2/ For etching, do use the solution suggested above. It's cheap, easy to find, doesn't create so many fumes and is easier to get rid off than Ferric Chloride, that is most often used. If you dilute with plenty of water, you can just pour it in the sink. Remember it is (more concentrated but still) hair bleach and pool detergent.
3/ Remember that the image you print must be inverted.


LINKS

PCB etching without Press n Peel Blue
This is where most of the inspiration came from but there are a lot of pages devoted to this. None of them describe the technique I used. I took bit and pieces everywhere...

PCB etching with transparency film
Etching Techniques
More PCB Etching Techniques