Earning my bread-and-butter as an engineer designing RF electronics, I've
spent far too much time working on SM PCBs.....
If you have the right tools, it's not so difficult to work with SM discrete
components down to 0603. 0402 parts are a bit of a pain, but even they can
be soldered by hand with care. Normal packages down to 0.25mm lead spacing
don't represent a problem if the PCB is well designed. PCBs intended for
hand assembly require different pad dimensions from those intended for
reflow. The only thing I wouldn't attempt is to mount a BGA package: they go
to a specialist! I also frequently build circuits 'ugly style' above a
ground-plane with SMD parts.
The trick is to get decent optical aids. Looking across at my bench, I have
a x10 binocular microscope (brought on eBay for about USD50), a large lens
magnifier, and a pair of 3dioptre throwaway reading glasses. I don't use
them all at once!
A good soldering tool is also important. I use a Metcal iron, having
abandoned the Weller TCP route nearly a decade ago. That seems to have been
the case in most of labs I visit. The price of the Metcal tools is
unfortunately significantly greater than that of the Wellers.
'Flood soldering' and then removing the surplus with solder wick is fine for
many packages. Don't forget that you can do your own 'hand reflow' by using
solder paste and a hot-air gun. A technician at a pager company I used to
consult for produced very good results that way, although it requires a bit
of practice if you're not to sent hot SMD parts and molten solder flying
around the room!
73
Chris
GW4DGU
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