Feb 17, 2015

DIY PCBs on the cheap: toner transfer with Box Packing Tape and a Hair Straightener / Iron

A few months ago I started to design an affordable 2WD Robot Kit to teach 20 students in a workshop in the AVM Master, at the Universidad Politécnica de Valencia, Spain.

That means also making about 100 tiny PCBs!




Want the short story? Watch the video:



Long story
Using the classic iron and magazine paper may be ok for one board, but I didn't want to repeat the process until getting the right and uniform heat and pressure needed. So I went the laminator way. Bought an old professional laminator (people say home laminators' plastic parts tend to melt at the needed temperature), modified the heat controlling circuit, and made the board with that.
The thin magazine got stuck if fed straight into my printer, so I fixed it to a paper sheet with regular box sealing / packing adhesive tape ( or "BOPP" packing tape http://en.wikipedia.org/wiki/Box-sealing_tape )

By chance one of the prints landed on the adhesive tape, and... it looked good! Tired of pealing paper magazine, and knowing that other people used parchment paper that could be easily pealed, or even made their own corn starch paper, I thought, well, lets try transferring from the packing tape (serendipity)!
With the laminator, the tape seemed to behave different than the magazine paper, so it didn't work. So, for the rest of the boards, I bought some cheap toner transfer paper sheets (no need to spend $ in Press-n-Peel film). Then I thought "there must be some small home appliance designed to apply uniform heat an pressure... hmmm... a electric pie iron maybe?", and suddenly the image of a hair straightener came into my mind. Exactly! That could do the trick. It was so obvious that someone must have done that before. After a web search I came across this old post by a guy called Ryan who was using his wife's hair straightener with success.
So I went to the next thrift store and bought a $8 used wide shape hair iron, with temperature control. After many tries I found the right temperature, times and method (using a thin cotton fabric folded four times, to distribute the pressure evenly).
You can see the real-time speed long version here.
I also used the same hair iron method with the cheap toner transfer paper to compare the results.
These are pictures of the boards after etching:
LEFT: toner transfer paper  |  RIGHT: packing tape    

LEFT: toner transfer paper  |  RIGHT: packing tape    
End note
If you intend to reproduce this process, do it at your own risk. Make sure the tape sticks properly to the paper: you don't want an adhesive tape jam inside your printer. An excess of ironing heat/time will start to melt the edges of the tape. Also the printed tape tends to shrink after a few hours.
Edit:
Have a look at the comments of hackaday's post about this method, there are good advices, opinions and alternatives there.




Edit:
Works great also for the silkscreens too. Just align the print using needles in two of the board's holes, and protect with transparent lack.




7 comments:

  1. I like. I might even try this today.
    Thanks for the tip.

    ReplyDelete
  2. Very funny. I stumbled upon this article today not realizing that I commented on it just over a year ago :)
    I tried the packing tape method today and it worked famously. Much much better transfer than magazine paper.

    Many thanks.

    ReplyDelete
  3. what kind of paper do you need to use?

    is it just a normal typewritting paper?

    ReplyDelete
    Replies
    1. do you have any tips in printing like how to get the original hole size of the parts?

      Delete
    2. The size consistence is better if you use "toner transfer paper" (search for it in your favorite search engine) instead of the packing tape.

      Delete