Printed film.

The film is a translucent blue colour which is glossy on one side and matt on the other - the printing is done on the matt side. Since this stuff is rather pricey, I printed three copies of the board along the top edge of the film. That way, I can make three boards from one strip of film. I found that the plastic became a little wrinkled due to the heat from the laser printer, but this didn't seem to affect the print quality.

Transfer and blank board.

Here's a piece of blank board and one PCB transfer, ready for heating. The board was cleaned with an abrasive block and then washed with IPA. You can see that the printed pattern is slightly reflective.

Transfer ironed on to board.

The transfer has been ironed onto the board. I used a normal iron, set to give a reading of 120-130 Celsius on a digital thermometer with K-type thermocouple. The temperature of the board didn't seem to get above about 100 Celsius, and was generally about 80.

Peeled transfer.

After quenching in cold water to cool the board, the transfer was peeled off. It came off easily - there was no stickiness. In fact, there was a slight crackling sound as it came away, which made me think of the edges of the trace giving way as the plastic substrate was lifted.

The board ready to etch.

Here's the board with the laser printed etch resist in place. The edges are a little rough, but it looks like there are no breaks.

Etching the board.

Hubble, bubble, toil and trouble!

Etched board.

Taa-daa!! It actually works, and it really does take about four minutes! Note the staining in the middle of the board. It was still there after all the other copper had gone, and I thought that this was a stubborn bit, so I continued etching for another 8 minutes - to no avail. Maybe it's staining in the FR4 itself. I checked with a meter, and got no reading even on a 2,000 megohm range.

After cleaning with IPA.

Apparently, there's a stripper available for cleaning off the etch resist, but Maplin don't sell it. I tried a tissue wetted with IPA and found that it did a fair job of removing the bulk (the deposit is quite thick). I used a medium pressure and continually refolded and wetted the tissue to present a clean pad as I worked over the board. You can see that the resist in the middle of the pads, and some traces, hasn't come off - methinks removal has come about by wet rubbing, rather than any true solvent effect.

After cleaning with abrasive block.

I then went over the board using the abrasive rubber cleaning block, and this seemed to work well - it's hard to see in the photo, but the result was bright copper all round.

Ready for drilling.

Some of the tracks are a bit ropey in places - I suspect there may have been some over-etching when I was trying to remove the stain in the middle. At one particular spot, the track is almost broken (but continuity is good). I'll probably bridge that bit, just to be sure.

Holes drilled.

The holes were drilled using 0.8 and 1mm PCB drill bits held in a small milling machine with a top speed around 2000rpm. The drill bits cut the material easily. The 0.8mm holes are for components, and the 1mm holes are for single SIL header pins. The photo below, with the blue arrow, shows the bit of track that nearly etched right through.

Drilled board, component side.

Here's the component side. There was some burr around the holes on this side - a quick spin with a spot cutter in each one cleaned them up.

The soldered board.

Solderability was excellent. If there was any tarnishing after 24 hours, it wasn't an issue.

Finished board.

Here's the board in use. It's a non-inverting 2-channel amplifier using an NE5532 op amp. It's for messing about with, so presets are used instead of fixed value resistors. The additional pins make reading resistance values more convenient. In a build with a specific gain, the presets can be changed to normal resistors and the pins left out.