Recycling!

I've been using the laser toner method for a while to make my PCBs. It seems to work well for me, I print out the PCBs using a  Samsung ML2010 laser printer, tape them to a cleaned copper board, then run them through a laminator twice. The heat fuses the toner to the board, and as long as your paper isn't too sticky, you can peel it straight off and etch.

I've been using this successfully, even for larger boards like my Arduino mega shield. The key variable seems to be the paper. I have the best results by cutting a square of sticker backing paper, using the stickers to stick it to the centre of a normal sheet of paper, then printing the PCB from Eagle. This works well, but I do need a sheet of stickers (like the A4 laser printing stickers) every time.

Other people have reported success with tracing paper, or magazine paper. I grabbed some tracing paper (two types, Goldline 63gsm and Goldline 112gsm) paper and gave it a try. It printed well, but didn't stick too well - you need to soak the paper to remove it, and most of my toner came off with the paper. Maybe my laminator wasn't hot enough :-(.

So, I'd run out of labels, my tracing paper experiments weren't working well - and then my eye fell on a discarded Farnell packing bill on my table. The Farnell packing receipts are printed on some sort of fan-fold sticker paper so that the address labels can be removed and stuck to the box. The whole bill is basically one big sticker! I cut a square, stuck it to a sheet of paper using the sticker I'd just removed, and ran it through the printer.


Perfect result, first time!  The toner transferred very well to the board:




The finished board (a SMT version of the tiny thermistor circuit) looks great and from the detail (on the lettering) this would work with much finer traces!

I'll start saving up all my old shipping receipts instead of buying printer labels now....



P.S. top tip - after the stickers have been 'laminated' and cooled, if you gently rub the back of the sticker with your thumb, a small 'bubble' forms that gently lifts the sticker backing away from the toner bit by bit. I get almost 100% adhesion with this technique.

Home-made Steampunk cogs

I like the steampunk look, and my daughter and I fancy building a steampunk keyboard.
Alongside my PCB building, I tried building some steampunk-style cogs to use as decoration or parts. I found some thin copper foil (0.1mm) from a sculptor's and restoration supplier Tiranti.

From Steampunk cogs

It's nice stuff, thin enough to cut with scissors, but thick enough to cover corners and bend around shapes without ripping. It should cover keyboard edges well.

One of the things I wanted to try was to use PCB etching techniques to make complex cogs or clockwork shapes. I put together a couple of templates (see the end of this post) and tried a few things to transfer the toner onto the foil - the best technique ended up being the label backing paper as per PCBs. Because you need to cover both sides, I mirrored the label and folded it in half - then placed the copper foil inside the transfer.

From Steampunk cogs

A couple of passes through the laminator, and the toner is fused onto the copper. I also printed a more complex mechanism onto normal PCB board.

From Steampunk cogs

I then used standard ferric chloride (PCB etching fluid) to etch the copper. You can either dunk the boards and gently stir the etchant, or (with GLOVES) rub it on the board with cotton wool or a kitchen towel.
Etching the PCB was pretty quick: etching the foil all the way through took a about twice as long as the PCB board. The etching worked well, most of the complex detail and cog teeth coming out well.
However, the toner is much more difficult to remove. With the PCB, the board gives the copper plenty of strength so the toner can be scrubbed away. With the foil cogs, they tear easily, so you can't scrub them. I tried soaking in acetone (nail varnish remover) and this removed some, but not all the toner. An agitated acetone bath (maybe an ultrasonic jewellery cleaner?) might remove more.

From Steampunk cogs

The normal PCB came out very well. The detail is good and the board can be scrubbed to remove all the black toner.

From Steampunk cogs

One of my ideas was to place some LEDs behind the PCB to shine through the board, illuminating the hidden pattern: this backlighting does give a really nice effect (shown against a normal lamp).

From Steampunk cogs

A nice large panel with plenty of clockwork mechanisms would look good instead of a numeric keypad, or as a lit panel in a PC case. Layers could even be stacked for a greater 3-d effect. This is just the research so far, I'll post more as it proceeds.


How to make a gear template (examples)

1. Generate a gear at woodgears.ca - I used tooth spacing 6mm, gear 1 teeth 100, spokes 5 and show spokes on.
2. Hit the 'print' button, then OK. My mac then allowed me (bottom left PDF dropdown) to import the PDF into iPhoto, basically exporting it to a jpg.
3. Edit the picture in Gimp. I did the following operations:
   
   1. Fill the outline with black
      
   2. Use Select - by color and then click on the background (white)
      
   3. Use Select - shrink to shrink the selection by 20 pixels (not from the image border)
      
   4. Use Edit - Fill with FG colour to fill it with black
      
   5. Use Select - all and Edit - copy
      
   6. Use Image - Canvas Size. Click the 'link' between the width and height to unlink them. Double the height and add two pixels.
      
   7. Click Image - transform - flip vertically
      
   8. Click edit - paste as - new layer. This should give you a mirrored image top and bottom, with a small line between them.
      
   9. Click file - save and export when prompted.
      
4. Laserprint onto label backing paper, heat transfer to copper foil, and etch.
   

Schoolboy Error

In my last two boards, I made a schoolboy error:
Both boards (due to different reasons) ended up being reversed left-to-right.
Now, during the transfer from paper to the board, it does mirror/reverse the image. I had 'overcompensated' and flipped the board twice, i.e. the wrong way.

Also, the stepper driver experiment was for the brand new 3.0 version, not the tried and tested 2.3 version (as noticed in the comments).

I've knocked together a version of a single sided board for the stepper driver v2.3 here - you want the v2 for the 2.3 board (eagle and .brd files provided). I dropped the ethernet connections (too many holes) and reverted back to the RepRap 3-pin connectors for the max/min endstops.

Here's a couple of etched boards, using the laserprinter/laminator/dab etching method:

From PCB

From PCB

I had to tidy a couple of edge tracks with a CD pen, but they came out well.

Here's my temperature controller (0-100 degrees C, controlling a relay) for another project:

From PCB

I bought some more copper board today from Maplins, so I should be able to make them a bit larger next time and avoid the issues with the transfer at the edge of the board.
Now to drilling several hundred holes with my new dremmel...

Etched boards

Here's the two boards I etched using the laserprinter/laminator method.

From PCB

From PCB

The laminator bound the laser toner to the boards really well. I used a few mm of ferric chloride, and dabbed/rubbed it onto the board with a cotton wool ball (wearing GLOVES). The centre etched first, and I was able to rub more around the edges to finish off the etch.

The etching worked really well. The detail came out fantastically - even the drill marks came out on the stepper board. You can also clearly see a minature mouse pointer in the centre of the temperature board - oops!

The toner bound so well to the copper that I had to scrub the completed boards with a green scourer and cif to get the toner off - it was harder work than cleaning the boards in the first place!
There is a small error on the stepper board (bottom left corner, just above the resistors). When transferring the laserprint to the board, before the laminator, I accidentally smudged a track. This is probably repairable when I add the via/wire bridges.

[Edit - I thought this was based on the Makerbot stepper driver (A3982) - but I actually picked up the files from the RepRap distribution, which are actually V3.0 of the stepper driver, based on the A3977. Wow, I'm ahead of the curve!]
Schematic:

From PCB

Ah! That's the way to do it!

Last night, I got round to making a couple of PCBs with the LaserPrinter method, using a couple of tips scavenged off the comments and interweb.

From PCB

I printed onto some sticker backing paper from some laserprinter address labels I had around. The first sheet, which was completely sticker-free, was a bit thin and bendy and got jammed up in the rollers and didn't print properly. After retrieving the sheet (and extracting a cat toy from the inside of my LaserPrinter), I removed a few stickers from the centre of a new sheet of stickers, so it was thicker and stiffer.
This printed perfectly.

I then taped on my cleaned copper board (Cif and green scourer again) and put it through a cheap home laminator machine.

This worked really really well. The toner transferred perfectly to the copper, and the sticker paper was left completely clean. It seems to have bonded well to the copper, so I will have a go at etching the boards soon.

From PCB

I re-printed my temperature controller PCB board. Since I only had a PDF of the circuit diagram, I had to mirror it before printing. Last time, I used a command-line utility and a converter - but this converted the tracks into a low-res jpg, which worked but was certainly not the best quality.
This time, I printed out the PDF version and measured the printed PCB (49mm). I then zoomed in, so the tracks were filling the whole screen (in the PDF reader) and took a screenshot. This screenshot can be cropped to the edge marks, and flipped in GIMP, and GIMP offers specific print options to print out at exact sizes - i.e. the size measured earlier. This worked well (apart from a minature mouse pointer appearing on my PCB tracks!)

Single Sided Makerbot Stepper Driver board

From PCB

I've been trying to get hold of the Stepper driver board for a little while, but while waiting I thought I'd try and make a single-sided version of the PCB that was easier to etch at home.
First task was getting to grips with Eagle, and downloading the .brd files from the RepRap repository. The biggest problem with the mix of through hole and surface mount components is that the pads end up on both sides of the board - the through hole pads are on the bottom, and surface mount on the top.
I loaded up Eagle and mirrored the through hole components onto the other side of the board. The plugs are now pointing downwards (not ideal) but at least the pads are now on the top side. Rotating the connectors by 180 degrees helped match the tracks to the existing routes.
This left lots of messy tracks on the board, but a bit of work tidied them up. I then went to work moving via's (that would now have to be wire links) and moving the via points so they are not underneath the surface mount components, as I'd have to through-hole solder them. I'm no circuit board designer, so I went with moving the components as little as possible, and re-routed the tracks to avoid or shorten the vias where I could. Straightening the vias helped avoid crossing wires, and some of the connectors could be connected directly.

I printed off the PCB and transferred it to the copper. If it etches well, and I can drill some holes without ripping all of the tiny tracks off the board, it might be worth getting some components to build up a version.

[Edit - here are the eagle board files for anyone who's interested. Probably there will be later versions that might actually work.]