Broken, Then Fixed, On/Off Button…

Broken, Then Fixed, On/Off Button…

I’m man enough to admit it. I broke the on/off switch on my first Crazyflie. There, I said it. In my defense though, it didn’t seem to be that easy to push in the first place. It was sticky and didn’t move smoothly. I probably applied too much pressure and finally, the little plastic bit broke off. I denied it for a while. I was able to dismantle the button enough that I could simply use a straight pin to turn it on and off. Eventually, that bit broke off as well so I decided to clean it up and desoldered the rest of the button leaving only the two pads intact. I used my propeller fork for turning it on and off for a long time. It fit the width of the solder pads perfectly. It wasn’t as easy as I would have liked it to be but it worked. Well, mostly it worked. Sometimes I couldn’t get it to turn on before the cold-boot timed out when I was trying to refresh firmware.

Eventually I decided I wanted to replace the button.


tweezersThere’s a page on the Bitcraze wiki that lists some commonly replaced components and gives some distributors through a “findchips.com” link. Unfortunately most of the distributors are not “direct to the consumer” so you’re expected to by in lots of 1000 or more (I don’t need 1000 power buttons for sure!). I found that Mouser Electronics actually ships direct to consumers so I decided to buy a few from them. They arrived pretty quickly.

magnified workI’ve never soldered surface mount technology (SMT) before so this was going to be an experiment for me. I hoped I’d not screw it up by lifting the solder pad with too much heat. I decided to do some research online first and found a few videos on SMT soldering. My main takeaway from all of my research was the following: apply solder domes to the bare pads first, place the button then heat the sides and apply just a little solder to get it all flowing, apply pressure once the solder is liquid, don’t heat for more than a few seconds (three or four), and finally, use leaded solder instead of silver solder to make life easier because it flows so much better. I don’t care about RoHS compliance. After all, this is an aftermarket fix and I just wanted to make sure I didn’t screw up the PCB so I used a high quality 60/40 Tin/Lead solder.

So, following my “key takeaways,” I fixed the power button on my Crazyflie! It worked great and the button feels even stronger and smoother than the original did! If you can’t tell, I’m really quite pleased with myself. My first SMT solder was a success, a simple task, but a successful one.
finished

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