DIY Surface Mount Soldering

[Michael B. Irwin]

It is possible to solder tiny SMD parts using ordinary  equipment if you
have a steady hand, good eyes, a magnifier and patience. I use a cheap
Radio Shack 15 watt soldering iron. File down the (interchangeable) tip
to a needle point and use fine gauge wire solder. Align the chip on the
PCB (with the help of a magnifier) and hold it in place by soldering a
pin at each corner. I have soldered (and replaced) 100-pin QFP (flat
pack) microcontrollers on many occasions using these tools. When solder
bridges occur between pins (as FREQUENTLY happens) use a fine-braid
solder wick to remove the excess solder. The remaining solder will be
enough to secure the pin to the pad.

To remove a QFP a special tool that heats up all pins at once is best.
Otherwise use a very sharp knife to gently cut the pins off each side
to remove a defective chip, and desolder the remains of each pin. The
biggest risk here is peeling the tiny pads off the PCB. Adapters are
available for a number of  many-pin flat packs which have sockets for
the chip and PCB pads or wire-wrap pins for connecting to a main board.
By the way, most DSP evaluation boards have connectors to bring out
control and data lines for interfacing to a larger system. The
difficult-to-do soldering has already been done for you on the board.