Making Printed Circuit Boards - Toner Transfer

For the home automation over IP project I needed a fast and easy method for creating printed circuit boards (PCB). After some research the “toner transfer method” seemed a solution to give a try.

Not being sure about the quality of the final result I designed the PCB with wide paths. This way a lack of precision shouldn’t be a big problem.

PCB Design

What you we need:

• a PCB design (obvious)
• a blank board (without photosensitive layer)
• magazine paper
• a laser printer
• an iron, preferably without steaming capabilities
• personal protection against chemicals (gloves, safety glasses and eventually a lab coat)
• glass or plastic bowl (never use a metallic bowl as etchant container!)
• etchant: HCl, H₂0₂ and H₂0
• thinner (acetone)

Step 1: Printing the PCB design

To print the design you need a laser printer (a copier should do the job too). An inkjet printed will NOT work. Common printer paper will work but to make the process easier paper with a glossy layer is recommended. You can use expensive photo paper but magazine paper will work too. Since the magazines a printed using ink the content will not transfer. Still I discourage the use of pages with pictures, look for text on a white background.

Before printing make sure your not using an almost empty toner and change the printer settings to the darkest possible mode (avoid toner-saving-eco-modes).

Step 2: Transferring the design to the board

Cut the blank PCB to the required size. To ease the alignment cut the paper with the design on 3 of the 4 sides to the PCB size. Keep 1 side uncut to make it possible to hold the paper without having to put the hot iron on your hand.

Ironing can be done on a piece of wood. Set the iron as hot as possible.

Iron used for toner transfer

Align the paper on the board  (toner side on the copper side of the board) and put the iron on the paper. Don’t move the iron the first 10 seconds to avoid moving the paper. Next, keep on ironing until the paper becomes brown. Make sure to iron all spots. After the ironing the paper will stick to the PCB.

Ironed PCB board

Step 3: Removing the paper

Now it’s time to get rid of the paper. Put the board in a boil of ho water. After a while the paper can be removed from the board leaving the toner on the copper.

After the toner transfer

If some paper sticks to the toner that’s no problem but make sure the paper is removed on the places without toner. Especially take a look at the places where you’ll drill the holes later on. If you let the board dry for a while the spots with paper will become white and very visible.

Step 4: Etching

WARNING: THIS STEP INVOLVES DANGEROUS CHEMICALS. BE CAREFUL AND READ THE LABELS ON THE BOTTLES OF CHEMICALS BEFORE USING THEM. USE PERSONAL PROTECTION!

Use a plastic of glass boil for the etchant. For the mixture I use this proportions: 90/8/2  for respectively H₂0/HCl/H₂O₂.

Since the chemicals don’t come in 100% solutions some calculations need to be done before mixing. I have a 29% HCl solution and a 3% H₂O₂ solution.  For 150ml of etchant I used 9ml H₂O, 41ml HCl and 100ml H₂O₂. If you stored the etchant for a while the will be a lack of oxigen. You can revive the solution adding H₂O₂ or using a bubble machine for fishbowls.

First add the water, next the acid and finish with the peroxide. Mix it using a plastic or glass spoon.

Gently drop the PCB with the toner on it in the etchant. Move it around to fasten the etching. After a few minutes the copper will dissolve and the etchant will become green. If all the copper is gone take the board out of the etchant and clean it with a lot of water (not in a metal sink…).

Etching a PCB

Adding some oxigen

Step 5: Removing the toner

Use a thinner like acetone to remove the toner from the copper.

Removing the toner

Cleaned PCB

Step 6: Prepare the PCB for population

After removing the toner it’s time to drill the holes and eventually protect the copper. Using a drill stand making the holes goes pretty fast. Especially when you etched the copper away. Aligning the drill will be very easy.

Now the board is finished it’s time to populate it and solder the parts…