Micro v1 Tracker with WLCSP-24 Package

A project log for DWM1000 Cat Tracker

Using the DWM1000s amazing ability to pinpoint tags to within 10cm we will track the cats positions in the house with amazing precision.

dryerziniaDrYerzinia 01/09/2017 at 00:530 Comments

I have successfully tested the Micro version of the tracker. None of the WLCSP pins have shorted and they are all connected. I can attach the programmer and load a build on the chip. This chip has a smaller program memory of only 16kB so I had to make some significant changed to the code. Basically I ripped out everything but basic tag functionality, No UART, no re-writable settings.

You can see how nicely the balls came out. I used tacky flux and a small hot air tool to get it to settle into place after putting it down with tweezers. If you look closely at the above image you will see a 0201 LED with concealed pads on the bottom I also managed to get down with hot air. This minimalist design left me with lots of space on the bottom and I managed to shove my logo in there.

This design end up with a board no bigger than the DWM1000 Module that sits on it. The only annoying thing was I used a footprint for a LDO that has a quiesent current of 25uA where I meant to use one with sub 1uA. I will have to search Digikey for one with the same layout because I don't want to get more boards made and I want to minimize sleep current, and that's taking up a big chunk.

You may be wondering how I used a 0.4mm pitch WLCSP with OSH Park design rules. The answer is I cheated! I lose out on some GPIO but by just shorting them to the inner pins I had to route out the design still worked out.

I actually found the WLCSP easier to solder than a QFN, probably because I never use solder stencils but I did manage to make a board of the same size with the QFN version of the chip as well as some extra goodies: