To peel or not to peel...

[crawler486]

Any of you guys use transparency printed with laser jet to etch your PCB?
I've done it with 2 of my pcbs before. It works but it needs retouching with a sharpie(permanent maker) because some didnt stick into the copper board.

Now my question is do I have to let the pcb cool down before I peel the transparency?

[Gringo]

Yes, let it cool down a while. I haven't tried throwing the pcb in cold water to speed the process, though.

[Elektrojänis]

I have used it for some time now too... Usually some retouching is needed, but I think I have managed to make at least one that didn't need any fixing.

I have found out that much depends on the temperature you use to iron it. I'm not sure if the ironing temperature is marked with dots on your side of the globe but here it is (1-3 dots, 3 being the hottest). I've found out that somewhere between two to three dots is good. Probably closer to three.

I usually use some paper (just ordinary copier/printer paper) under and over the PCB and the transparency I'm ironing to be sure the transparency will not stick to the iron or other stuff it shouldn't if it melts.

I iron it for quite long (5 minutes or so) so the PCB warms up too. The toner sticks to the PCB better like this. It is usually best if the transparency almost (but not quite) melts.  So experiment with the temperature. I usually just press the iron on it and keep it there for a while and then take it up and press it on to a bit different position. If you iron it like a shirt it wil probably move and smear.

What comes for the cooling, I usually just let it cool. I think that trying to speed up the cooling might make the toner crack or something, but I have not experimented with that too much.

And yes... I would use (or at least try) pnp blue or similar products if my local supliers had any. Next thing I'm going to try is the photo method (or whatever it should be called). My workbuddy says it is the only way...

[zener]

I've tried to put one in a refrigerator to speed up the cooling and nothing wrong happened.

Transparency film (acetate) has never failed me. I always have it printed in a photocopying machine.

I start with scrubbing the pcb with a green scrubbing pad. I do it until the copper becomes shiny. I just put the layout on top and put the iron on it and leave it there for 5-10 mins. The iron setting is on 3 for silk. After 10 mins, I take the iron and do it as if it is a shirt. I press hard and make sure every portion of the layout is being given a hard-pressing by the iron. I often pay special attention to the sides where the ground and other off-board connection pads are. Patience is the virtue to observe.

Then, I wait it to cool on its own. After cooling down, I just peel the film slowly, pressing with my thumb on the portion of the layout as I start to peel on it. I very seldom have a pcb where a trace is cut because it didn't sticked.

It keeps me wondering why some people here are struggling to get a good pcb out of blue press 'n peel which requires strict control of iron pressing. Furthermore, it's more expensive than the transparency film through a photocopying machine

[crawler486]

Yesterday I tried printing from a magazine I got from office.
I must say its way better than my experiences with transparency.

[RedHouse]

Cooling is good, another thing that helps is to run cold water over it while you *slowly* peel away your medium of choice.

(I use Avery Label backing stock)