– March 9, 2011

This post is a speciale dedicace to anagram’s map of Paris

I just received a bunch of cool new chips from my favorite dealer. The problem is that a lot of them are surface mount ( SOIC, SOP, MSOP, SOT23 and sometimes worse…) and I cannot really force them into the perforated board I was using before. So I decided to try and make my own PCB using the toner transfer technique (see here and here for detailed french tutorials). The metro map is a perfect material for this because:

1. It has plenty of fine details.
2. This week end was the half-marathon of Paris and I could print the race track on top of it.
3. I like it (Even if there’s no rabbit inside).

1. Inkscape craze

First step is to remove trains, trams and boats to make more room for the actual metro tracks. Then make everything black and white and stroke the metro tracks with white so they are visible on top of black background. In the end, everything that is black will be copper, all the white will be epoxy.

2. Printing on shiny paper

Second step is to print the map (dont forget mirror mode) on a shiny paper, like supermarket ads.

3. Laminator transfer

Third step is to transfer the black toner into the copper clad. This is made by pressing hard and heating, which is conveniently achieved using a laminator. Mine was a bit weak on the “heating” side so I added a hairdryer as well. The laminator was rated 0.6mm but swallowing 1.6mm PCB did not cause any obvious problem.

4. Paper removal

Leaving the board inside water, the paper becomes soft and easy to remove. The toner stays on the copper clad.

5. Etching

The board is etched using a mix of tap water, chlorhydric acid and hydrogen peroxyde (100/60/40). After 2 minutes, the solution becomes all green (sorry no pictures for this step, I was too focused…)

6. Cleaning

The remaining toner is removed using acetone. The result is not that bad. SOIC8, SOIC20 and SOT23 should be ok, not sure for the other ones. There are still some small holes and black marks. Hopefully this will not happen on smaller boards (this one is A4).

About martin

François

Posted March 12, 2011 at 11:54 PM

Hope C. did not mind about her hairdryer! The folks in charge of organizing the Paris half-marathon in 2012 should consider giving this piece of PCB to the finishers instead of a stupid medal!


martin

Posted March 13, 2011 at 12:43 PM

Or gold PCB for the winner, silver for 2nd, bronze for 3rd . But I wonder if chlorhydric acid can dissolve gold….
- Reply
  
  Alex
  
  Posted March 19, 2011 at 7:35 PM
  
  You could just etch three normal ones and then plate them after. The gold and silver should only attach to where their is metal right?
- Reply
  
  Jon
  
  Posted March 20, 2011 at 9:06 AM
  
  Only thing I can think of that dissolves god is Aqua Regia, which is a highly acidic and volatile mix containing both highly concentrated Nitric Acid and, I think, HCl.
  - Reply
    
    martin
    
    Posted March 20, 2011 at 9:51 AM
    
    Dissolving god sounds like a good plan . Did we start already ?

Philip

Posted March 20, 2011 at 5:58 AM

by the way that formula is Hydrochloric acid, water, and H2O2 (hydrogen peroxide). “Oxygenated water” really translated wrong. its water (H2O) with an extra oxygen (H2O2)
- Reply
  
  martin
  
  Posted March 20, 2011 at 9:50 AM
  
  Looks like you’re right. If I google for “oxygenated water”, I get plenty of websites selling this for drinking, which I will definitively not try with what I used… I just edited the text. I’ll check the exact formula on the bottle when going home tonight.
  - Reply
    
    martin
    
    Posted March 20, 2011 at 9:59 AM
    
    Actually, “hydrogen peroxyd” is written on the bottle on the picture just above so this proves it. I guess “eau oxygénée” is just a poetic interpretation of the scientific name. Thanks for noticing it !