I need a a solder stencil for a upcoming PCB, and was wondering what material and thickness to use. The smallest pads are on a 127 QFN package, and are .3mm square. Because this is so small, I was thinking 2 mil (.002") thick. What material? I am thinking type 302 stainless steel.
Any thoughts? The stencil will be machined using FIB (Focused Ion Beam).
Stainless is good for production, but stainless stencils are normally pretty expensive. Not sure about FIB, and what its capabilities are.
I’ve used Ryan O’Hara’s $25 Kapton stencils (0.003" thick), which work well even for very fine pitch components.
I wouldn’t go thinner, as you might not get enough solder paste for the bigger components. If you’re worried about too much solder on the fine-pitch pads, you can slightly reduce the size of these pads in the stencil.
The SS stencil will cost me under $10.
I will do what you said, and reduce the size for the fine pitch pads.
Please tell us where you can get SS stencils for under $10!rp181:
The SS stencil will cost me under $10.
I can get it machined free, SS sheet is only about $7.