This is a solder paste stencil machined from a beer can. [Simon Ludborzs] spent quite a bit of time dialing in his process to get to this point. Note the nice crisp edges of the openings. That’s a big change from his first attempt.
When looking for a way to make his own stencils he considered two options: plastic and aluminum. He produced both (more about the plastic stencil and his reflow process is discussed in this post). Plastic is a bit easier to work with since it lays flat. But it proves to be too thick. After applying paste with a squeegee there’s way too much solder on the pads. Aluminum beverage can walls are much thinner, depositing less paste.
We’ve seen soda cans used in the past, but they were produced through an etching process. [Simon] cut these holes using a CNC mill. This required a bit of…
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