More components are only available in SMD packages. For hobbyist assembly the options are to buy breakout boards or solder SMD.
Since components are usually packaged in a couple of SMD package types I am trying to put together a set of guidelines for choosing packages that are compatible with hobbyist skills and tools. I would consider hobbyist level tools for SMD assembly as -- soldering iron in the $50-$100 range (new), for magnification a $40 visor (like the B&L) and tweezers.
For the kits I make now I use the following guidelines --
- Passives 0805 or larger
- Min Lead Pitch for SOIC or QFP -- 0.5mm
- No QFN, LGA or BGA
- Prefered package for gates, BJT, FET --- SOT23
- Diodes SOD123 (or larger)
I am interested in recommendations on component selection, minimum tool requirements and assembly issues. Specific tool changes (like solder tip size) that enabled you to do SMD assembly with your existing tools would be useful too.
Thanks.
Answer
0603 isn't too bad to solder by hand (I won't do 0402 or smaller though).
SOT23 is probably a good guideline (for diodes too, not just transistors); there are some SOT323s that are smaller that are a pain.
I would avoid certain SOT23-6 parts because it can be very difficult to determine which way the package is supposed to go. (For some dual MOSFET packages it doesn't matter.) We had one where there was a slight bevel along one edge. Grrr.
I would also avoid SOD123 because of the backwards nature, if possible. SMA/SMB/SMC aren't as much of a problem.
And avoid those cylindrical diodes (LL-34 / MELF) like the plague! they will roll off the board.
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