Holiday Trinket: Take Two

Turns out it was essentially impossible to solder the transistors upside down; It didn't help that my solder paste was "expired" and incredibly runny. The method of using a toothpick like CNLohr failed miserably on the tiny pads. Despite knowing that everything was going to go badly, I still tried to put one trinket together.

I ordered a new set of PCBs with the transistors corrected and got them a few weeks later. Today I attempted to assemble a trinket again, but this time with the aid of a stencil. I ordered a simple plastic solder stencil from OSHStencils so I wouldn't need to precisely dab solder paste anymore.

Stencil in hand.

Using the same runny solder paste from before, I just had to spread a blob of paste over the stencil using the provided plastic card until all the holes were filled.

Stencil aligned and ready to go.

After applying the paste, placing the parts, and heating it all up on the hot plate, I got a much nicer result:

Don't look at the left one.

The paste was still spilled out a little but that was to be expected. I finished up the backside manually with the soldering iron and put a battery in. Disappointingly, the top most LED slowly lit up but the ring did not oscillate. I will need to do some debugging and get some fresher solder paste (some may have run a bit and caused a small short). The last time I used the paste, the joints definitely didn't look this dull and flat.

On a side note, OSHPark provided some free jellybeans!

Hooray!