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Comment by Vexs | Hacker News Reader

I don't think that modern boards are really repairable at all beyond component replacement- 4+ layer stackups being the big reason. If there's a way to do anything to those boards besides total replacement I'd be super interested to know.

The techniques here are also way beyond basics I think- like, you look at most guides for repair and it's "idk just solder some bodge wires on there, here's what a good joint should look like"

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Andrew Zonenberg posted a Twitter thread a year or two ago where he fixed a missing PCB trace some layers down a PCB, with a stereo microscope, precision mill and very steady hands.

Edit: here's the thread. It's a 6 layer PCB with a short on L5 that needs to be fixed from the L1 side.

https://xcancel.com/azonenberg/status/1468825231225540611#m

Holy cow! I've been pushing around a TQFP48 tonight and thought I was pretty good.

If you enjoy that sort of thing, check out this guy's videos. Lots of trace repairs (including below the surface), pad replacements, etc. Quite impressive to see it done.

https://www.youtube.com/@northwestrepair

10/10 read

Mostly when things fail it's not a trace, it's components

For boards with a bunch of layers and BGA/LGA packages, that have internal manufacturing errors or damage (e.g from overflexing), repairs can be untenable.

If the parts all have pads on their perimeter, then a jumper wire can replace internal traces. If the pads are underneath the part, and the trace is only internal, than a jumper may not be feasible, unless the damage happens from the surface in, in which case each layer can be jumpered at the damage.

>If the pads are underneath the part, and the trace is only internal, than a jumper may not be feasible.

BGa pad repairing is very common, here is one example: https://www.facebook.com/watch/?v=1077341457703029 (sorry can't find non-facebook link)

nope, people still repair >8 layers boards like it's nothing. Some even do "chip repairing", literally remove the expoxy of the IC to fix bonding wire, or remove the security key/module on the chip.

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