This pic is job number 38 of version 3.4.5 of the Mitochondrion. That square chip is the dinky little computer that runs everything. It connects to the outside world through all those pins. Those pins are at 0.8 mm spacing, 0.4 mm between them and yes, this is the hardest thing I’ve ever soldered. It came out quite nicely:
The secret to really hard soldering is to do a bunch of moderately hard soldering first.
(For the geeks, it’s a Picaxe 40X1, which is really a PIC16F887 running a BASIC interpreter, in a 44-pin QFP package. 7 ADCs, I2C two-wire bus, external oscillator overclocking it to a whole 16 MHz!!!w00t!!!)
I’ve found a new thing that my phone can do. It makes a passable microscope, zoom factor 4 or so.
Now, the really hard part – getting the little sod to work, then to work with all the other bits, then to keep working…
(Couldn’t not try it sunday night – yup, not working. Chip has power and connection to the laptop for programming, but reset line is misbehaving, or at least doing sufficiently complicated things that, on a sunday night, I can’t work out if what is it doing is what it should be doing. Possibly, chip is permanently resetting. This is solvable, but not right now. Curse you, paid employment!)