Minimum slot width?

Sure they do. It's just shifted negative a bit.

Cheers

Phil Hobbs

Oops! You're right. I missed that. Sorry.

De nada, thanks for looking. They got back to me--their minimum slot is

Cheers

Phil Hobbs

Crazy idea, maybe they could thin ~80% of the way with a big mill... leave a bit of epoxy with the copper. But it would reduce the stress enough.

George H.

That can be a problem, too; what about the solder-paste and mask? Any excess paste applied will endanger the slot's main virtue, the nonconducting air fill. Worse, if it ever grows whiskers...

The missing part of the footprint won't have a paste pattern.

Cheers

Phil Hobbs

Light is very "flexible" and can do cutting (laser).

Glass is somewhat immune to photons, and FR4 is mostly glass. also scorched FR4 is conductive.

a water jet cutter might work.

As I mentioned upthread, excimer and femtosecond lasers cut just about everything, glass included, and don't leave charring. Nd:YAG, diode, and CO2 lasers can char organic materials, but don't always.

Yup, maybe.

Cheers

Phil Hobbs

Really small PCB via holes are drilled with lasers.

Maybe do a few of those and then join them up with a really small nibbler. ;)

Cheers

Phil Hobbs

torsdag den 2. august 2018 kl. 17.51.34 UTC+2 skrev John Larkin:

but if you are going to fill the hole with copper it probably doesn't matter if the resin is slightly charred

If you run high enough frequency AC through a wire EDM, can you cut glass too? :^)

Aside (even without the substrate being what it is): PCB is probably not the best EDM material, on account of copper being much more difficult to cut that way, even in foil I would suppose.

Tim

Maybe that's because they think we are now all wearing MAGA caps :-)

That sounds impossible on any standard FR-4 board. They would lose too many end mills. Anyhow, all the low cost manufacturers I know wouldn't even come close to 0.8mm. I think this is the kind of stuff where one has to cough up the dough and go higher end. These guys claim their "special bit" can do 0.021" which I think comes to 0.54mm:

The tolerance for "special" is +/-0.004 though which could be too much in your case.

If it has to be slotted smaller maybe you could go flex-board (Kapton) for that part of the board and have it lasered out. Or maybe for the whole board could be flex.

EDM cuts conductive stuff.

I was very sceptical at first, but I'm coming round--the Donald has all the right enemies. ;)

Check out PCBway next time. Really a good outfit. Their standard quick-turn boards can have 0.8mm unplated and 0.5mm plated slots, no extra charge.

I think this is the kind of stuff where one

Thanks, that's interesting. We've become quite disillusioned with our local folks (PNC in Nutley NJ) because their prices have gone up a lot and we've had trouble communicating with them, so we're planning to switch to Advanced Assembly in Aurora CO for our next serious order.

This is a preproduction version of the APD power supply. Getting it through approvals is the customer's worry, but I really want that to be easy, so I'm overdesigning the creepage by about 2x from what I think they'll need (80 mils minimum, with at most 300V between traces).

Cheers

Phil Hobbs

He's crass and crude, but he's on our side. And he likes to win.

It's possible that he's smarter than he looks, but crass and crude work for him. I've seen that happen.

He has got the Kochs now against him.

Fake news :-)?????? I like to look at things from more than 1 perspective.

US is getting very isolated these days, new world order: China, Russia, Europe.

If he's crass and crude, one would rather keep some distance.

Winning isn't a virtue, nor a reliable expectation. Mature persons can "meet with triumph and disaster, and treat those two imposters just the same".