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I'm going to solder a small pcb with reflow process and I'd like to use a stencil for that because the components are too tiny for hand soldering iron. The pcb has a QFN32 (0.5mm pitch and exposed pad), and some passive components, most of them 0402 and few 0603. I haven't done this before and I wonder if there's some specific solder paste intended for stencil use.

This is the board. https://github.com/jgabcgr/cc1310

Thanks in advance!

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Solder paste is designed for use with stencils. As long as you don't buy a cheap-o low quality paste, you should be fine. I heard a good description somewhere; good paste consistency should be that of smooth creamy peanut butter. For good results with a stencil, you don't want it to be too thin and watery (like when peanut butter separates), or thick and clumpy (like the bottom of the jar).

Clumpy paste will not spread properly over the stencil, and may clog and not remain on your PCB when the stencil is removed.

Thin paste will not hold its form after the stencil is removed, and may spread out, causing bridging.

Also remember; solder paste has a finite shelf-life that will be listed by the manufacturer. Typically this is 6 months to a year, if stored properly. Your results may worsen as your paste ages.

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  • \$\begingroup\$ As a side-note, this site isn't intended for product recommendations. To narrow down which paste you choose, do some research to see what's available, check reviews, and possibly check to see what other hobbyists recommend in other forums such as EEVblog. I'm sure you can find more information there. \$\endgroup\$ – Daniel Mar 2 '17 at 22:28
  • \$\begingroup\$ Daniel Giesbrecht, Thank you very much for your answer, That was exactly what I was looking for. Now, to be exact, I'm considering to buy the "XG-Z40". I haven't checked it yet but I don't want something more expensive than this. I'll check its recommendations in the related forums. \$\endgroup\$ – jgabcgr Mar 2 '17 at 22:40
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    \$\begingroup\$ The consistency, but not the flavor, of peanut butter. \$\endgroup\$ – pericynthion Mar 3 '17 at 0:45

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