I purchased a PC board with lots of interesting I/O that's being controlled by a single microcontroller in a 44-pin QFP package. I'd like to access the I/O lines directly so I could hack in my own microcontroller, but the footprint of the QFP package is too small (less than .05" lead spacing) for me to connect wires directly to the pads. There are no larger pads anywhere on the PC board I can connect to. Ideally, I'd mount some sort of socket or header in place of the existing microcontroller, that I could then connect wires to. The speeds aren't so fast that I need to worry about lead length.

There are obviously lots of prototyping boards for mounting an SMD that allow you to connect headers. What I ideally need is different... something that be soldered into an existing PCB footprint and gives access to the pads. But I haven't been able to find resembling this!

Would love to hear any solutions-- I'd love to repurpose this board and give it some new life!

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    \$\begingroup\$ Have you tried 30AWG wire yet? \$\endgroup\$ – Ignacio Vazquez-Abrams Apr 11 '17 at 17:04
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    \$\begingroup\$ can you give us the actual spacing, not just a "less than"? My guess is that it's 0.5mm spacing (QFP isn't usually sold with smaller pitches, but that doesn't mean it doesn't exist), and you might indeed find ribbon cable for that \$\endgroup\$ – Marcus Müller Apr 11 '17 at 18:29

No, a reverse, dip to QFN type adaptor is not readily available. This is not a typical prototype or debugging method and you would have up roll your own solution.

Typically this is done by soldering magnetic wire (32 awg) to a trace or the removed chip.

enter image description here

It's normally not pretty.



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