Thursday, January 25, 2018

Oopsie – but it's alive!

Last time, in High-altitude help to prepare for low-altitude testing I wrote about receiving a batch of custom Airball circuit boards (v2) to prepare for Ihab's flight testing. I bet you – dear reader – are waiting with bated breath to learn how that went. The answer is... well, but not well. It turns out that as part of my cleanup work on Ihab's EAGLE board files, I managed to swap Ihab's carefully-backwards-designed placement of the SparkFun Fio v3 board to the forwards orientation. Which is fine, unless you, uh, actually need to mount the Fio backwards.

They work perfectly, you just can't mount a Fio on them in the way that we need to; so I got to do the re-order walk of shame. At the same time, I made some adjustments to v3 mainly to the silkscreen text on the boards based on seeing some of them in person, and I rounded the corners a bit more, as the previous radius was too small. However, I was careful to leave all the SMDs in the exact same places so that the stencil I ordered would still work just fine.

These are the new boards (on top) and the v2 boards (on bottom), top side:

And bottom side (notice how the Fio pins are swapped on v2, bottom):

A stainless steel solder paste stencil is used to apply exactly the right amount of solder on all the SMD pads, which makes placing parts and soldering them much simpler, and produces way nicer results:

And then the parts can be manually placed with tweezers and a steady hand:

I used a hot air rework station to reflow the solder, and the tricky part of the boards is done, all of the SMD parts are on:

With the addition of all the sockets, the board is complete, and it works! This is the pressure sensor side (missing an absolute barometric pressure sensor for the moment):

And the Fio side:

It's alive and well, and reporting data. It's still on the (high altitude) ground though, so next step is to get some of these over to Ihab for some "low altitude" in-air testing!

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