Work log - Week 8 - March 16, 2022¶
Wednesday - 3/16¶
Class Links¶
https://www.jpl.nasa.gov/edu/learn/project/space-origami-make-your-own-starshade/
http://cba.mit.edu/docs/theses/19.09.calisch.pdf
After Class¶
David Taylor at Charlotte Latin Highschool was kind enough to invite me over to their Fablab to finish up my previous week’s project on their CNC Router.
This project took a decent amount of time, and as always, meant chasing down a few inconsistencies. Managed to learn a few more things about Aspire, and get the hang of the work flow down.
Did I mention how nice David was to help me with this? With his help, we finished up by about 2:30pm. David helped with some of the finishing and sanding. I owe David and his two boys lunch.
Thursday - 3/17¶
I slept a lot, I’m out of shape. A bunch of 12 hour days in a row wipes me out. Worked on a couple of new boards to prepare. One is a ADXL343 accelerometer breakout board. One was a “fixed” attiny neopixel board with added i2c pullup resistors. And the final new board was a 16 neopixel attiny based board.
Friday - 3/18¶
Went in to the CPCC Fablab and started work on the new boards. I had two quick failures. In one case, the endmill seemed to eat away much of the traces of the board. And in the next case, the board started moving during the contour cutout tool path. I stopped it, and then I took the board out. It had gone about 3/4 through the board. I tried a pair of wire snips to cut it out, however this only managed to split the board down the middle. I threw the board across the room. Stupid board.
I think the problem was that the board was warped, and the tape wasn’t strong enough to hold it down.
Met with Cori and Adam and learned some more about electronics, including pull up resistors, sinks and sources and how many microcontrollers handle them, and various other electronics information.
Cori was able to get her board milled and soldered up, and after a bit of debugging, was able to get it to work successfully.
Later on, I was able to mill a few different boards and soldered them.
Also created a couple of solder masks (using Kapton Tape) for Adam to be used on his SAMD11C based programmer. They turned out really nice.
Soldering a QFN package¶
We received a solder heat gun station. I put it to the test with some “Quickchip” solder paste. This was my second attempt.
My first attempt seemed to be okay, but it was quite obvious that despite a large amount of heat directed at the board (the copper started oxidizing), you could still see that the pasted was composed of tiny balls of solder, and not the shiny, cohesive blob that you would want to see.
This attempt was a bit better (though not perfect). I added extra length to the traces of the pads where the chip was to be placed. Even for pads that were unused, I extended the pads out to the sides of the chip.
The idea was to use these copper pads to act as heat pipes, to transfer the heat to solder paste underneath the chip, and thus melt it. I have to say, this did seem to work much better than my earlier experiments.
The laser cut Kapton tape stencil’s also continued to work very well.
Some images of the ADXL343 soldering process:
Saturday - 3/19¶
Spent a lot of time trying to program the neopixels. I’m trying to figure out how to have more control over them, and slowly learning this.
Working a bit more on group projects and programming.
Sunday - 3/20¶
Lot’s of documentation.
Monday - 3/21¶
Spent a large chunk of the day working on new boards. Had a hard time getting the boards to mill due to the lacklaster PCB’s that are not flat, nor will stay stuck down to the sacrificial board on our Roland SRM-20.
Spent a couple hours trying to get one good board. Made one board, and the traces were all over the place; not straight, and basically garbage. I managed to at least semi-get it ready by using bodge wires (haven’t had a chance to test it other than seeing if power light comes on, which it does.)
I managed to finally get a good board milled out, and soldered both boards up (fixing the first one took too long.) By the time I finished, I was tired and went home, haven’t gotten around to programming them.
Tuesday - 3/22¶
Met with Adam, Denny, Cori and David (all at slightly different times) and discussed different project with each.
Denny was very helpful in finding a short in one of my experimental ADXL343 accelerometer board. Denny also answered a whole bunch of questions about building electronics. Thanks for the help Denny.
I helped out Cori a small amount with programming her neopixel/attiny board and the button. It didn’t blow up!
Met with Adam and discussed some of the designs and where to go from here.
Met with David and discussed FabAcademy stuff.