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PCB UV exposure box
AdeV:
As Andrew said somewhere up the thread, one of the things you have to watch for with plastic is whether it cuts out UV or not. Fortunately, there's a nice simple test - common or garden tonic water fluoresces a lovely cyan colour in UV light. So, pop the light box back on the timer, fire it up, and check it out with a bottle of the (apparently delicious) Fever Tree tonic water.
Sure enough, a lovely light blue glow. I think I'll be OK with this.
Now to go cut up some more circuit board and do the test over again!
PekkaNF:
That is good to know. I need to check that trick one day. I have affinity to Fever tree tonic and I got bitten by acryllic sheet that would block over 95% of UV - no good for PCB work.
Pekka
AdeV:
--- Quote from: PekkaNF on January 05, 2019, 11:14:18 AM ---That is good to know. I need to check that trick one day. I have affinity to Fever tree tonic and I got bitten by acryllic sheet that would block over 95% of UV - no good for PCB work.
--- End quote ---
Yep - I can't remember where I read it, but it's a great check.
NEWS: I just made my first PCB!! There were one or two problems.... actually, just one broken trace, although it looked like there should be more dead ones :scratch: so I'm having another go now.
Pictures soon..., because I know that :worthless:
AdeV:
Sooo, after a few experiments, 3rd time lucky! (pic 1)
After etching... one track has undercut (pic 2). Oddly, the tracks that LOOK broken are fine, and one that looks fine isn't. I tried to fix it with some solder, but no joy.
Decided to drill it anyway (pic 3), silly me forgot to check the drill bit size and the holes are a little too large, but there looks to be enough pad left to solder to. Too late to start now, that's tomorrow's job. I'll bridge the broken track with a tiny bit of wire.
So, if the soldering goes well, then the jury will be back in! The provisional verdict so far is:
* The LEDs are now doing the job nicely
* The drilling machine works fine; it's a bit of a chore setting it up without any alignment marks, but I pretty much got there OK
* Cupric Chloride works just fine as an etchant. A bit slow, perhaps, but maybe I didn't make it strong enough, I'll try a new batch another day.
* Will it solder....
AdeV:
So, update...
Nope! I think I drilled a bit too much of the pad away... that and the copper oxidised too quickly, or maybe there was a hint of photoresist left on it, or something. Basically, the solder refused to stick properly.
So... I'll make it all again next weekend; in the meantime, I'm off to buy some tinning solution!
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