Manufacturing PCBs with Laser Printers – Toner Transfer Technique

 
As an electronic hobbyist, you would love the fact that homemade circuit boards are not just cheap – they are also an ideal way of manufacturing cheap custom PCBs if you intend to produce professional grade DIY circuit boards in bulk at home. Building PCBs with a laser printer probably seems like a very efficient method. However, the manufacturing may not be that simple. Don’t get intimidated just yet though.

Here is how you can etch your own laser PCBs with the toner transfer technique.

What are the essential components?

You will need:

1. A laser printer – and be careful not to use an inkjet printer for toner transfer technique.
2. A photo paper/ glossy sheet from magazines
3. A copper PCB – single or double sided
4. An iron (that you use for pressing clothes)
5. Electronic driller for mounting the components
6. Really small drill bits (1mm and smaller)
7. Circuit diagram (made on software like Proteus or Eagle) or a PCB layout (made on DesignSpark PCB)
8. Chemicals like hydrogen per oxide and Hydrochloric acid, Acetone or thinner
9. A container for holding the etchant preferably made of plastic
10. Hacksaw for cutting boards.
11. Sandpaper
12. Safety goggles

The Process of Making Laser PCB with Toner Transfer Technique

1. Selection of photo paper and printer settings: In order to make laser PCBs, you will have to get your hands on a photo paper or magazine sheets which are glossy (the already printed ink of the magazines do not get transferred to the copper board). Next make sure that the printer settings are accurate before printing out.  Print out the mirror image of the layout or circuit – after transferring the image to the board, you can visualize the real circuit.

2. Setting up the copper board:

Don safety goggle before proceeding any further.  Cut the board with a hacksaw to an appropriate size. Then, you have to remove the oxidation layer from the copper board as well as finger prints, grease and oil. Scrub lightly and do not go overboard as it might remove copper. Clean the board with simple water. Use soap if necessary. You may also use isopropyl alcohol for cleaning. Let the board dry out, and be careful not to leave fingerprints on the surface.

3. Transferring toner to the copper board:

Neatly cut out any excess paper and then cautiously lay the printed side of the paper facing downwards on the copper board. You may make use of a tape if you think that the paper might change alignment during the process.

Set the pressing iron on max temperature limit, and position the iron on the paper. Exert pressure for 10 seconds and the carefully move it. Continue the process for a maximum of 3 minutes, making sure that you applied heat adequately to all sides of the copper board so that the circuit gets printed on the board.

Immerse the board in a warm water bath so the paper gets soft for peeling. With the help of running water and a soft toothbrush, remove the paper from the board to reveal the board with the toner prints. After removing the paper, observe the tracks for breaks or shorting. Just in case you think that there is something wrong with the circuit, remove the toner with acetone/thinner and repeat all of the procedures above.

4. Etching the laser printed PCB:

A mixture of hydrochloric acid (HCL) and hydrogen peroxide () in the ratio of 2:3 is used as an etchant. When making the solution, always mix HCL in H₂O₂. Sometimes, ferric chloride and ammonium persulphate is also used. Submerge your board in the etchant solution. Upon removing the board, you will observe that the excess copper has been removed and copper traces are etched.

5. Removing the toner:

The toner has to be removed to reveal the copper traces. You may use acetone/thinner to achieve this purpose. Use a multimeter to check connectivity.

6. Drilling and mounting components:

For through-hole components, you will have to drill holes. Keep the PCBs on a wooden board before drilling. Since tiny bits are used for drilling, go through the process carefully. Insert the components and solder them. Voila – your custom laser printed PCB is ready.