Advice Making Custom PCB with Many Holes

Electronics
#1

I’m wanting to make or custom order a PCB that has many small holes in it.
The goal is to resemble PVC mesh like this. The only component on it would be 1515 leds like the ones in the picture.

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The holes are 0.55mm in diameter in a hexagonal pattern with 0.75mm between them (as in, there is 0.75mm of plastic between the edges of neighboring holes)
The holes are just for appearance, they won’t need to be lined with copper.

Would the normal custom PCB companies accept a design like this? Could I make it in the makerspace?
I think it would only need 1 layer, so I wouldn’t need a very complex mill to make it.

Should I pick a specific material to make this out of? I’m not sure if that many holes would make a normal board really fragile. I would likely attach the finished board to laser cut or milled acrylic though, which may fix that.

#2

If you are wondering why, my goal is to have something I can see through that also emits light.

It is common to use that sort of PVC mesh as “eyes” on costumes that you can see though. If you want the costume to have glowing eyes, you would light up that mesh from the side. But that means you can’t light it very precisely, and half the light is shining directly in your face.

When I saw how tiny these leds are, I thought “you could put those on the mesh itself without even blocking your vision.” And that’s where I got the idea to use a custom PCB as mesh.

#3

Here is an example of the “normal” way you would make these light up.

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(This one was designed and built by me)

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#4

The lower right corner somewhat shows your concept. I used Pads on 0.1" centers but Holes could be used much closer. Used free EasyEDA CAD program which links to JLCPBC for manufacturing. Five 4"x4" boards with shipping are $3.50.

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#5

Most PCB houses will make something like this, but they won’t be happy about it because it’s putting undue stress on their machines and the board can be more prone to snapping. Some places have a policy of x number of drills per sq inch, anything more than that and you pay per drill.

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#6

The shapeoko 3 in plastics would I think be accurate enough for this if you had the right tooling to make the hole; i.e. the correct drill bit with a 1/8" shank ideally.

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#7

Thank you! I’ll keep a lookout for a Shapeoko 3 on the calendar for this then.

#8

Yes, you can definitely use the router to drill a bunch of holes in a piece of plastic. Here I used the machine to drill a grid of holes in the core material before I added the fiberglass. The holes allowed the air to escape inside the vacuum bag. A much better option than drilling them by hand.

For small holes, you would use a peck drill cycle. One way to align the workpiece is to bore a pair of 0.25" holes, stick a pair of dowel pins into those holes and then just keep the workpiece pressed against the pins. As long as it stays touching the pins you know exactly where it is, until you turn the machine off. You will want to use a low-profile clamp to keep it pressed up against the pins. Don’t hit the clamp!

If you’re super lazy you can also just click the outline of your part and pocket the whole part into your spoilboard. Think chalk outline around a murder victim. This is not very accurate, but it does work occasionally and it doesn’t require any prior planning.

I don’t really get why the LEDs need to be on the same sheet as the optical grating. But it might be worth a shot. If you use regular PCB material, it may crack and / or generate a lot of dust. Would the nomad be big enough?

carbide drill bits on ali express

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#9

Yes, but BEWARE if you’re using fiberglass resin PCB material that the drilled dust is hazardous.

#10

Thank you! This is really helpful!
And that flexible PCB is nice. Maybe I could get it made out of that material to avoid cracking and throwing up fiberglass dust.

I guess my main reason is just “because it would look cool be unique”.
Part of the appeal to me is that it’s going to be so hard and complicated to pull off. That would be a good conversation starter, and it would just feel more rewarding to pull off.

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#11

@keoliver I found you a student for the fiberglass class!

Also, I bought one of these and I set it up to output a screen. I haven’t designed an enclosure or anything yet.

It should work for fiberglass-sized particles. I know the metal shop was also interested in particle counts for grinding dust.

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#12

In my experience rapid PCB houses tend not to charge extra for through holes. I have only seen major price jumps for plated castellated holes and blind vias.

Have you quoted your PCB design with and without the holes?

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#13

I saw a post in Discord that the Nomad can be used for PCBs if you take a new course. Is that the fiberglass class you’re talking about?

#14

Ah, thanks! I hope that’s true, since that would simplify this a lot.
I’m currently learning how to use KiCAD, so I don’t have a design to test this with yet.

#15

Yes. There will be a specific class for it (PCB/Fiberglass). The expectations for cleaning up will be much higher.

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#16

Thanks!
If I take that, would I also be able to use the Nomad to mill acrylic?
If I could use it for both, then I can skip learning the Shapeoko completely. That’s the only other thing I’d use it for. And I’d only be milling stuff small enough to fit in the Nomad.