[Vexs]

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"

[dsvf]

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

[Vexs]

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

[dmbche]

10/10 read

[idiotsecant]

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

[dlcarrier]

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.

[mrheosuper]

>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)

[mrheosuper]

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.