soldering xson8s sucks but the board works

A project log for TP-BMP

Black Magic Probe remixed to replace the silly fingerprint reader on my X220. Might work on other Thinkpads too. ARM debugging for all!

zakqwyzakqwy 09/15/2017 at 21:310 Comments

As the title says, soldering the tiny XSON8-packaged level shifters was a real pain in the ass. I didn't make a stencil for TP-BMP but I did stretch the footprint out a bit, so I tried hand-soldering them but to no avail. You can probably see why:

[above: image of the bottom of the level shifter in XSON8 form, sitting on a standard 0.1" spaced board for scale.. Note that this is really an LGA, so unlike a QFN the pads don't actually extend to the side of the package. Not hand-soldering friendly.]

I probably should have gotten a stencil and started over with a fresh board, since I have a few extra. Instead, I bodged on a bit of solder paste and hit the components with a hot air gun. This didn't work at first, so I touched 'em up with an iron, tested the board, desoldered two of them, cleaned up the joints, etc .. repeat for a lot longer than I should have spent on this project. But finally...

[above: screenshot of using ARM gdb to detect, attach, program, and detach a #NeuroBytes Interneuron board. Yay!]