I’ve looked for a diy way of making a solder paste stencil online. I couldn’t find anything simple. There are lots of examples of using a thin copper plate, then etching away the holes. I thought I’d try something else.
I started with a thin piece of plastic from a food container. It’s clear and 0.007" thick. Then I overlaid a printout of the PCB pads, and drilled 1.2mm holes through the template and the plastic. The hard part was keeping the drill from wandering. I also had to “clean up” the plastic holes as there were a lot of burrs.
I tried some 0.8mm holes too. Some worked, others I didn’t get clean enough after drilling. I don’t know if I can drill holes suitable for a TQFP, but I might have to give it a try. There was some minor smudging which seemed to be worse after the first board when the stencil was clean. I just fixed up the smeared paste with some tweezers before placing the components.
The photos below are of the stencil, the solder paste on the board, and the finished job. The resistors are size 0805.
Not bad for an afternoon of DIY
edit: sorry for the huge pictures. On the plus side, you can see the granules in the solder paste!