Home-made PCBs and vias

[shapirus]

Some old DMM's I've worked on made via's by rolling little strips of some copper alloy, into cylinder's with just a little overlap. IIRC, nothing extended out of the hole by any amount.

Now that's an idea. I have some copper tape with a glue layer. It can be used not only for creating copper traces, but also for vias. That's going to be very labor intensive though.

[shapirus]

A related question...

How do you drill small holes (say, sub-0.6mm) without breaking the bits? Presumably there's some kind of precision pillar drill available that I've yet to come across.

Near zero chance of doing it with a hand-held drill.

I bought this mini drill press specifically for the task: https://www.aliexpress.com/item/1005004599678055.html

Works very, very well. Zero runout (I guess that's the term for the bit going slightly off the axis so that its end draws a circle instead of a point), zero axial and radial play, and that's pretty much all that matters.

It's built down to a price, but they made the really important parts really nice. There seems to be a small percent of people having worse experience than mine, so YMMV.

[Howardlong]

A related question...

How do you drill small holes (say, sub-0.6mm) without breaking the bits? Presumably there's some kind of precision pillar drill available that I've yet to come across.

Near zero chance of doing it with a hand-held drill.

I bought this mini drill press specifically for the task: https://www.aliexpress.com/item/1005004599678055.html

Works very, very well. Zero runout (I guess that's the term for the bit going slightly off the axis so that its end draws a circle instead of a point), zero axial and radial play, and that's pretty much all that matters.

It's built down to a price, but they made the really important parts really nice. There seems to be a small percent of people having worse experience than mine, so YMMV.

Interesting. How small can you go with it?

[shapirus]

Interesting. How small can you go with it?

I think the smallest I have tried so far was 0.6 mm, as that's the diameter of the wire I use to make vias and I can't remember having to drill holes for anything smaller than that. Could easily go smaller if I needed, as it's really very well aligned. One of key factors is to press the PCB down firmly to the base and not let it get lifted, or moved otherwise, as the drill bit starts to go into it. The PCB moves, the drill bit breaks. Extra attention required when you drill smaller holes first to be later used as guides for larger bits: those larger bits effectively act as screws, trying to lift the board up.

I'm assuming hard alloy bits (typically tungsten carbide based), of course. They are super brittle. Steel bits are more tolerant to misalignment, but even when made of HSS, which is a wear resistant type of steel alloys, they get dulled very quickly by the glass textolite material, because, guess what, glass is hard.

BTW I have also successfully drilled half-holes with it, where the center of the hole lies right on the edge of the board. Hold the board firmly, lower the drill very very slowly, and it works just fine. The diameter was 1.0 mm in that case. This means that the lateral stiffness of this drill press is also quite decent. Might probably be used for some very simple light duty milling jobs as well, even though the RPM (about 3k/min IIRC) is nowhere near what is good for milling, but I really don't want to abuse it this way not to cause excessive wear of the axles and bearings.

[tooki]

A related question...

How do you drill small holes (say, sub-0.6mm) without breaking the bits? Presumably there's some kind of precision pillar drill available that I've yet to come across.

In terms of hobbyist tools, a Proxxon "dremel" tool (I use the IBS/E myself because it has extremely low runout of 0.03mm maximum, despite costing under 100 euros) together with a Proxxon drill stand (I use the MB 200). Unlike Dremel's wobbly-ass drill stand that uses a plastic thing to hold the machine, the Proxxon drill stands are all-metal and are rigid enough to drill tiny holes.

I think 0.5mm is the smallest I've tried on it so far, but thinner should be possible.

At my old job, they had a dedicated PCB drill press, and using that, I drilled 0.3mm holes into aluminum sheet. Lemme tell you, though, you just look at a 0.3mm carbide drill bit the wrong way and it snaps! Working with them requires extreme care and focus; don't do it on a day when your hands are shaky or you've had too much coffee, nor when there are people milling around!

[sleemanj]

You can use a hand-held (eg dremel type) rotary tool to drill down to 0.3mm, as long as you use HSS bits, don't bother trying to use carbide ones at that size as you will of course break them too easily.

Of course maybe the hole will end up a fraction bigger than 0.3mm, but does it really matter.  0.3mm is the thinnest HSS bit I think you can get.

Micro size HSS will wear out quickly, they are disposable consumables, if you use 1 or two per PCB, it's not the end of the world.

Keep the bit length short.

[shapirus]

Micro size HSS will wear out quickly, they are disposable consumables, if you use 1 or two per PCB, it's not the end of the world.

This is a good point btw. Considering the amount of hassle they save, they may be better than carbide bits even if you use a few per PCB. And maybe even cheaper: they are actually dirt cheap.

[shapirus]

Interesting. How small can you go with it?

I think the smallest I have tried so far was 0.6 mm

Just to test it, I tried to drill a 0.3 mm hole, which is the smallest bit size I have. No issues whatsoever, worked like a charm. And it was a carbide bit.