Adventures in PCB Burning

Resulting "good" PCBs

Resulting “good” PCBs

In some of the projects I’ve been working on I’ve had to design a basic to intermediate circuit to control the electronic components of the project (typically a bunch of LEDs, which you don’t want to use a Raspberry Pi for because the resulting current of multiple LEDs will be too much for the board, same goes for Arduino which recommends: 1 LED per pin).

There are a number of how-to’s and instructions out there for the various methods and I’ve tried just about all of them, so the following is my notes and thoughts on the different techniques.


The Methods:

  • Toner Transfer
  • The Flame Thrower
  • Baking Parchment Paper
  • Toner Transfer Paper

The TLDR version is that thermal transfer paper is the best for me, especially cause I have the dreaded Brother toner.

Toner Transfer

Toner Transfer PCB

Toner Transfer PCB

This is one of the most popular and quite successfull methods out there. My cousin Corey Kingsbury even did a great instructable on it long ago (http://www.instructables.com/id/DIY-Arduino-or-The-DIY-Duino/). The one catch is that the type of toner you use can play a difference. My laser printer is a Brother so I fell into the unfortunate category of “Brother toner doesn’t work nearly as well”. I did try it out numerous times, using Brother toner, the recommended Staples Glossy photo paper, and spare iron (even used a cheap laminator I purchased as well) and got mediocre success about 1 every 8 tries.The image shows a successful burn and you can see the results are not super great.

The Flame Thrower

This is a variation of the Toner Transfer method for Brother toner. Idea is same as Toner Transfer but you use a blowtorch and a thermally conductive plate to get a higher temp on the toner and crystallize/transfer it better. I tried this with a number of different conductive plates (wearing a respirator! Be very careful with heating materials, you don’t want to breath anything toxic, check the MSDS info beforehand) with mixed results; it was hard to get an even spread or see what the board looked like, some parts would be underdone transferring little or no toner while other parts got too hot and the board started to melt/burn. I used aluminum (too bendy when mounting), glass in order to see the board (a terrible idea it shattered almost immediately when applying heat), and I eventually settled on weldable steel (from Lowes).

Parchment Paper

Out of desperation of frustration I learned that you can also printer to baking parchment paper. I tried this but found that the toner didn’t transfer well, tended to move, and as the heat was applied the paper liked to curl and not stay in the same spot without tons of tape.

Thermal Transfer Paper

Toner Transfer Paper

Toner Transfer Paper

After some frustration results and more reading online I stumbled across Thermal Transfer Paper and decided to purchase some (this kind:  http://amzn.com/B011RYZANO) for $15 there are 100 sheets, I figured that was a better value than the Photo paper I purchased. It arrived and the instructions are the same everywhere and not helpful at all, here they are for entertainment value:

Description: 100% brand new and high quality. Remove the white paper- laser printer (or copier) to the PCB map- hit the smooth side- apply to the copper- and iron into the machine or rapid transfer to plate. DIY Transfer Paper (fan-made high-precision electronic circuit board must have the material). Heat transfer law making circuit boards- circuit board is drawn graphics- laser printers print in thermal transfer paper- transfer paper and then covered in Bonded Copper- after heating- the melting of the toner completely adsorbed on the deposited copper- and other cool tear off transfer paper- you can see the graphics board has to transfer to the Bonded Copper on the black anti-corrosion layers- that is- we want to map the PCB- and finally to corrosion- and that we want to obtain the PCB board. The process of making iron tools used in heating or over-presses. We serve the transfer paper for the production of circuit boards dedicated thermal transfer paper- with its production of circuit board has the following advantages: 1. plate with high precision. 2. plate cost. 3. plate-making speed. 4. can produce double-sided. Usage: Circuit board with a laser printer to print to the circuit diagram of the smooth thermal transfer paper. Raised with the laminator between 150-180 degrees Celsius- the heat transfer printed circuit side of the paper deposited in the Bonded Copper on the transfer; the system can also be used instead of iron plate machine- hand transfer. Remove the transfer paper after printing- the Bonded into the ferric chloride solution to corrosion. Finally- remove the circuit board using toner. Aution: You can use the laser printer! Can not use inkjet printer. Package included: 100 x Heat Toner Transfer Paper

So you can see from the photo that there’s a brown side and a yellow side. The brown is a medium card stock while the yellow side seems to be the special chemical paper (made of a layer of wax and then a dissolvable substance like dextrose, or glucose, some sort of sugar/starch compound.) and the two can be peeled away leaving a thin (and likes to curl up) yellow paper and a sticky/sticker side to the brown card stock.

The idea is that the toner is applied to the wax layer, that is placed on the copper PCB and transferred via heat using an iron or laminator, then the board and paper is placed in water and the “paper” is dissolved/pulled away leaving only the toner on the copper.

Now the frustrating part was how to properly use the Thermal Transfer Paper, the instructions do not seem to match reality. I did a lot of trial and error to find out the proper usage. I printed and applied to the brown card stock (which gave results like the photo paper),  the yellow side which didn’t work well at all. Finally I tried applying to the inside sticky brown side and the shiny inside yellow paper.

Thermal Transfer Paper PCB

Thermal Transfer Paper PCB

The last is the key, you apply the toner to the the shiny yellow inside, this is where the wax layer existed, and I believe the brown card stock is there to protect the wax until it is ready to use.

You still have to iron on the paper, which if not done correctly can leave some thin or underdown traces; but the results I got were far better than the Toner Transfer Method (even though I have Brother toner) and more consistent almost every attempt was good.

 

 

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