Soldering SMD's

[Stewart Pye]

If you have to desolder SMD you can buy a "chip quick" kit. This contains
flux and low temperature solder. It's used like this....

Apply flux to pads of chip you want to remove.
Put plenty of the special solder on the joints, on every pin of the chip. 
Go around the chip a few times, trying to get all pins hot. The special
solder will mix with the old solder and will be molten at a lower temp than
normal. This gives you time to melt all pins at once. After 30s or so the
chip will just fall off. Just make sure you get all the solder off before
replacing the part. 

For caps and resistors I use wick to get rid of most of the solder, then
heat up one side then the other and give it a shove with the iron. I only
destoyed one pad when I was first learning with this method. 

Packages like soic with .05" spacing are OK to solder conventionally,
however I've found the best way for .25" spacing stuff is to cover the pins
with solder, so they're all briged, then use wick to get the excess off (as
others have described).

I use "soder wick" for desoldering. I think the manuf is Chemtronics. It's
coated with something that makes the solder stick to it really well. This
is one reason not to touch it. If you touch it it doesn't work so well. I
use cutters to pull a bit more out and cut off the used portion.


Regards, 

Stewart Pye


BTW: I dreaded the thaught of replacing SMD stuff in the beginning but once
you get used to it it's a piece of cake. Oh... maybe that's an overstatement!