Holes in PCB

[robotix3]

I was just wandering what the heck these holes in this RC quad-copter remote PCB are? It's a single-sided board and they aren't plated. It's an IR remote so it's not some weird RF thing.... I guess it has something to do with the wave soldering?

https://drive.google.com/file/d/0B8gXTJQEnbqQMHZaZndvSVZ6MDg/view
https://drive.google.com/file/d/0B8gXTJQEnbqQQXlfR3c4dEFoeVU/view

[m98]

Real crappy soldering going on there.
Those holes almost look like former vias, which where removed, as the board was redesigned to single-layer. Maybe they forgot to change the drill file? Can't see any other purpose for them.

[robotix3]

My guess is that they are using the pcb from a different controller because it is cheap and they are not using the mounting holes.

I'm talking about the little ones, way too small for screws

[sleemanj]

Bored designer playing connect the dots maybe.

[TassiloH]

This is an FR2 (phenolic paper) board. I remember reading somewhere that for high volume, cheap production, FR2 is not drilled, but punched. You would need a special tool for every PCB layout with all the holes punches in it. I figure it is maybe cheaper to combine several board layouts into one punching tool (same hole pattern, different copper layout). That would keep the tooling costs lower, but would result in unnecessary holes in every board.

[robotix3]

Oh well that is interesting. So they make an aluminum punch and for a whole series of boards to save costs, that is very smart...

[Ian.M]

To me, it looks more like they redesigned it for more SMD parts, and rather than making a new punch or modifying the existing one by removing punch bits from the tool, they just worked around them, maybe so they can react to varying component prices by a board respin to choose the cheapest SMD or through hole option for each.

[Alex Eisenhut]

This is an FR2 (phenolic paper) board. I remember reading somewhere that for high volume, cheap production, FR2 is not drilled, but punched. You would need a special tool for every PCB layout with all the holes punches in it. I figure it is maybe cheaper to combine several board layouts into one punching tool (same hole pattern, different copper layout). That would keep the tooling costs lower, but would result in unnecessary holes in every board.

Winner. This is called "punch'n'crunch" PCB, for low-cost, high-volume products.

That's exactly what they do, it's a special die and they made a die for several models.

I do similar things in the RF world, several different converters fit in the same enclosure. You just have to keep track of where the mounting holes are.

[wguibas]

looks like it was printed on a color laser printer, the secret service is tracking circuit boards now.

[robotix3]

looks like it was printed on a color laser printer, the secret service is tracking circuit boards now.

Ahhh yes