SMD: Surface Mount Device Soldering

SMDs are mounted using: reflow soldering, wave soldering and hand soldering.

• Hand SMD soldering is done for small-scale SMT mounting, using good old soldering irons. It is the most common and easiest method for the electronics hobbiest.
• Reflow SMD soldering is where you screen print solder paste onto the PCB land pads, placing the SMT component on the pad, and passing the assembly thru a reflow oven or otherwise heat the entire assembly to melt the solder and produce the solder bond. It requires an oven or other heat source, solder paste (usually applied with a stencel), and is greatly improved by a solder mask, but can be done at home. Care must be taken to avoid frying the components. Hand repair or touchup is often required.
• Wave soldering is where you glue the SMT component onto the bottom side of the PCB and then float the assembly over a wave solder pot to soak everything in molten solder. This is very fast, but difficult to do without destroying the components.

Reflow:

Toaster ovens or hardware store hot air guns for smt reflow.

http://www.sparkfun.com/tutorials/59 Reflow soldering on a skillet.
http://youtu.be/CO2Vv0YztBE Solder paste can be manually applied and components placed and re-flowed in a toaster oven

Wave:

Use electric skillets for dip (wave) soldering and tin/lead plateing. The basic problem with home plating is that a roundness forms that causes the leads to slip off the pads. You can use wick to remove the the rounded tops. "Mopping" the solder over the board with an iron can result in uneven solder hight which can prevent all the chip leads from contacting the pads. Again, solder wick can remove "bumps"

One problem is that the package picks up moisture and turns to steam if heated rapidly as in wave soldering. This can cause delamination of the plastic from the die or leadframe^. I've observed the problem appearing as blown output pins. Smaller packages are rarely a problem. Typically you can pre-bake the chip for 12-24 hours at low enough temperatures to prevent rapid generation of steam (Altera suggests 12hrs at 260F).

http://www.cornwell.demon.co.uk/micro1.htm MELTING METALS IN A DOMESTIC MICROWAVE

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