Very clean etch! I am jealous.

Thanks Dick!
This method is really easy, I'll elaborate for readers who have not used this method.
all I needed was:

• laser printer
• drafting film (architects and artists use it). two prints taped together for the master.
• 45 year old Radio Spares light box small with two 'black light tubes'. I think I exposed for about 5 minutes.
• Something to set the resist and allow the unset part to be washed off.
• pcb precoated with photoresist
• Ferric Chloride
• a small retangular plastic tray full of boiling water which a smaller tray for a bit of Ferric Chloride and the pcb. Gently hand swirl the Ferric Chloride about for 5 minutes and it's done.
• and of course, easy to use schematic capture and PCB programs. I recommend gSCHEM and PCB-RNG because theyre open source and Free, you can give them to your friends, if you teach, you can give copies to your students, no one will arrest you or sue you for a million dollars!

This method is repeatable, one can use the master artwork again and again. With all new gear and no prior experience, just make up some test strips of pcb and expose them in one minute intervals, perhaps 1 - 6 minutes then expose, and compare for the one with the most contrast, this can be easily done by eye. Etch to confirm the time and quality of output.

Note: the only reason I had this PCB was because I messed up the SMT transistor pinouts (doh!) and couldn't use it. I made a batch of 10 for that project in 1999, and they're still in use in industry to this day, doing level detecting duties in the livestock feeding industry. There is a PIC16F84 in there and they're still good after 23 years continuous daily use!

Cheers,
Terry

 

Presensitised board is getting expensive, especially if it doesn't work first time. I just send mine off to China. I get plated through holes and solder resist - something I can't make myself.

Have to agree with this, China is so cheap and the board quality so high, that messing around making them yourself, with the time, hassle and chemicals required, just isn't worth it. Upload your board design to JLC and you will get it in a week, all nicely made, double sided, with solder mask, silkscreen and in one of a number of different board colours (I just tried the purple, they came out quite nicely). Sometimes, you just have to accept that there are much better ways of doing things...

 

Hello. I believe this couple of threads might be of your interest:

https://forum.allaboutcircuits.com/threads/my-new-etching-tank.117346/

https://forum.allaboutcircuits.com/threads/my-etching-process.115229/

I've made a few tweaks and improvements to my processes since I published those posts. If you want to know more, all you have to do is ask.

 

How I make PCBs

 

Ok so I did end up being lucky with vellum and deep black toner after all. (I had a print shop print it). I think my main problem is a cool-ish environment since I'm in a home with central air. It did take a few times of transferring the board between ferric chloride (etchant) and sodium silicate (kinsten DP-50 chemical) and warming both chemicals up, but in the end, the board did turn out decently. It also didn't help that the board I had left had an almost transparent Presensitized coating on it. That's what forex (an overseas company, I think in UK) does to their boards. And I only ordered from them once when I needed to cut a large board (305x450mm) into a few equal pieces.