DIY PCB

This is an outline of my trials in DIY PCBs. This has been a learning process. There are tons of articles on this subject online. Many people seem to have their own techniques and tips on etching PCBs. This will be my contribution to the pile of knowledge out there. My hope is to provide first hand experience to help make your DIY PCB attempts easier. This was my very first attempt at doing this so I am sure you will find a better more efficient way of doing it. In short the process is very straight forward. But like all things the devil is in the details.

• Copper-Clad PC Board 115x160mm (Radio Shack Part# 276-1499)
• 16 oz. PCB Etchant Solution Ferric Chloride (Radio Shack Part# 276-1535)
• Press-n-peel Blue PCB Transfer Paper (www.dipmicro.com Part# DE2706)
• 1 NEW black Sharpie Marker fine tip (not the very fine tip)
• Clothing Iron
• Scotch-Brite Heavy Duty Scour Pads by 3M
• Dish Soap
• Sheet of printer paper
• Laser Jet Printer || Photo Copier
• 2 x Sterilite Plastic Shoe Boxes
• Pair of yellow rubber dish gloves
• Eye protection.

All design was done on a MacBook Pro. The software below is also available on Linux and winblows. Except for OSX Preview. You can use any image editor of your choice.

• Fritzing Electronic Design Tool
• OSX Preview
• Open Office

OK, this is a challenge in its own right. I am not going to go into detail on how to design your circuit. I can see how just designing circuits can be an art form. Creating a clean PCB layout was a little more challenging then I expected. Depending on the complexity of your layout you could find yourself spending quite some time figuring out how to lay your traces on a board. In my case it took a few reiterations of the design to get it right. The software I used is called Fritzing. This is an open sourced project designed for hobbyist in the spirit of sharing. This is a great little tool and very easy to use. It is currently in an alpha state but totally usable. In short this was the process.

• Open Fritizing
• Choose the PCB design window in the bottom right.
• Draw up your circuit.
• Click the “Export Etchable PDF” button in the bottom bar.

• Open the PDF you exported with Preview.
• Click File → Save As
• Change “Format:” to PNG
• Click Save

• Open Open Office
• Choose new “Text Document”
• Click Insert → Picture → From File…
• Align your image in a way that you can paste as many of them as possible on the page. Be sure to leave at least a 1/2” separation between each image.
• Save and print a copy of the page and make sure you are happy with the alignment.
• Once the alignment is to your satisfaction place a sheet of the Press-n-peel Blue PCB Transfer Paper into your LASER JET printer. This can not be done with an inkjet or any other type of printer. It must use toner. Make sure that you have the paper placed so that your page will be printed on the dull side of the paper.
• Cut out as many of the circuit transfers on one piece that will fit on your copper clad board.

This is an easy process but took a little trial and error to get it right. You can follow the steps on techniks.com. Here are my notes on getting a good transfer to the board. This is the most critical part of the process.

Gather your materials for the transfer process.

• Clothing Iron
• Press-n-peel Blue sheets with your laser printed circuit.
• Dish Soap
• Scotch-Bright pads
• Piece of printer paper
• Copper Clad board
• NEW Sharpie marker

1. Clean the board well. I can not stress this enough. A recommendation on a few sites was to use Comet cleaner instead of the methods recommended by www.techniks.com. I made the mistake of trying this. In my experience just use a Scotch-Brite scouring pad. Under a stream of water scrub the copper clad board until it is shiny. Make sure it is scrubbed well. Missing the slightest spot can result in starting the transfer over and a wasted piece of the Press-n-peel. After the board is shinny use a little bit of dish soap and a clean sponge to clean any copper residue off the board. Running a thin stream of water across it should result in a smooth line of water down the board. If the water breaks direction down the board or seems to route around spots then repeat the cleaning process. Do not touch the boards surface with your fingers after it has been cleaned. Even a little bit of oil from your fingers can cause problems with the transfer.
2. Set your iron to the synthetic setting. Temperature should be around 300° F.
3. Place your PnP blue circuit design, dull sided down, onto your copper clad.
4. Place your sheet of paper on top of that making sure you have not moved the PnP blue.
5. duration 1 minute - Put the iron on top of the sandwich you just created. Do not move the iron around. Allow it to sit for ~1 minute without being disturbed.
6. duration 2 minutes - After a minute start moving the iron up and down the transfer using NO downward force. Allow the weight of the iron to do the work. Using downward force will cause the transfer to smear. Found that out the hard way. You may want to hold the sheet of paper with your free hand to prevent it from sliding around.
7. duration 1-2 minutes - Remove the paper. The PnP should have adhered to the copper. Lift the iron and press down on the transfer making sure you have applied heat to all parts of the circuit design. Do not slide the iron. You can use the pointed side of the iron to make sure you are getting good transfer on the small traces.
8. After you have applied heat to all parts of the design take the board and run it under cool water until the board is cool enough to handle with bare hands. Do not peal off the transfer yet.
9. Now start pulling the transfer off slowly making sure the traces have stuck to the copper. If you notice that the traces are not applied stop pealing. Dry off the board and transfer as much as you can and reapply the heat from the iron. Once the board is back up to temperature use the pointed side of the iron to apply heat to the problematic traces. You may be able to save the transfer.

If all goes well you should have a clean transfer of your circuit on the copper clad.

You may find parts of the traces that have small holes or unfilled areas. This is where you use the Sharpie marker. Use the fine tip to dab marker ink into the missing areas. As the spots dry give it another layer or two of dabs. You should not need to draw any large lines. Only do a little touch up. I find that the sharpie marker works really well for this.

If the transfer fails…

use your Scotch-Brite pad and scrub the board clean. Making sure all the toner transfer is removed. You can then start over with the same board.

This is the easiest part of the whole process.

Gather your materials for the etching process.

• Copper clad board with your circuit transfered.
• PCB Etchant Solution Ferric Chloride
• Sterilite Plastic Shoe Boxes
• Rubber gloves
• Eye protection
• Good ventilation

1. Pour enough of the etchant into one of the boxes to fill it 1/2”.
2. Fill the other box with clean water.
3. Place the copper clad board into the etchant solution and let it sit for 2 minutes.
4. After two minutes start rocking the box back and forth gently. Allowing the etchant to wave too and fro over the PCB.
   
5. In about 5-10 minutes you will see the copper start to dissolve exposing the fiberglass board under the copper.
   
6. Keep agitating the mix checking on the board until all the exposed copper has been dissolved. Do not let the board sit after the exposed copper is gone otherwise it may start to eat into your traces.
7. Remove the board from the etchant solution letting the excess etchant drip from the board.
8. Place the board in the tub of water. Clean it thoroughly making sure there is no etchant left on the board. Give it another good rinse under the sink.
9. At this point only your traces should be left with toner still on them.
   
   Go ahead and scrub off the toner transfer from the copper with your Scotch-Brite pad and drill your holes.
   
10. Lastly cut your PCBs as you see fit.
    

You now have a custom made PCB. By the way. If you want text etched out in the copper don't forget to reverse it before you print it on the toner transfer paper. As you can see I found that out after I already printed the PnP blue and didn't want to waste it. :D