Dead-bug soldering is an acceptable method to patch a production circuit board per IPC-7721. Awww, even looking at it is painful, there must be a lot of industrial horror stories behind these photos...

...and deliberately tombstoning an SMD resistor to install a mod wire to a production board is acceptable, too. From now on, whenever I do this I'll claim the board is hacked using the recommended industry standard technique.

...and the classic hack: stacking DIP chips on top of each other, lifting or cutting QFP pins for mod wires, are all accepted by IPC-7721 as legitimate methods for patching a production board. Interestingly, IPC-A-610 even allows stacked SMD resistors and capacitors by design, not limited to a modification.

Mod wires do have to follow some rules: secured by epoxy glue, not perpendicular to the pin, not crossing a component, and only a single wire should be used at a single pin. Also, zero-ohm resistors are acceptable pin bridges.


@theruran Stacking DIP chips on top of each won't work for most systems. But it's a classic way to do a RAM/ROM mod in a 8/16-bit computer because these chips are special - all data and address pins have the same pinout and are connected together on the same tri-state bus to carry the same signals, so you can stack one on another. The only different signal is the Chip Select pin, you cut that pin and solder a jumper wire to the decoder logic you added so only one chip is selected at a time. tag

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