Hey, super advice from all of you! That same thing works for Leadless chips as well!
I regularly solder 0402s and 0201 here at work. The big advantage we have here is a microscope at each of our benches.
A few additional hints and tricks:
To remove fine pitch ICs we just mask the area around the chip with KAPTON tape (high temperature) and heat the area with a heat shrink gun until the chip falls off. A razor knife or small tipped tool can be used to apply a SMALL amount of upward pressure to help it (too much will bend any pins not yet free). Many of the fine pitch chips have a pad on the underside that is soldered to the board to act as a heat sink (small leads don't carry heat away from the chips very well). With these chips that's the only way you are going to get it off. (Check the data sheet or the replacement part to see if one exists.) Since you are heating the area it should come away all at once. DON'T be in a hurry! I've spent 2 or 3 minutes waiting for the chip to come away with a very hot gun.
Some notes:
- Watch for discoloration of the silk screen and the solder mask, they give you a good warning that you are overheating a spot.
- The chips themselves are pretty heat resistant: I just quickly looked at a data sheet for a plastic TSOP and the lead solding temperature is +300°C and the storage temperature is +160°c. As long as you spread the heat around evenly, the solder will melt long before you reach those temperatures
The previous advice for soldering the new ones in is great except if your chip has the heat sink pad on the bottom. For that type I clean the pads with solder wick (carefully they do lift!). I then add a small amount of solder to several pads spaced around the footprint. Add flux to all the pads including the heat sink area and drop a short piece of fresh solder off the roll on the heat sink pad (flattening it first helps). Then just hold chip in place (non-matalic tool is best since this takes awhile and the handle of your razor knife will get quite hot before you're done, my lesson is healing quite nicely
) and start heating with your gun. You will feel it start to squish down as the solder melts. This will not take as long as removing the chip since the hot air can now get under the chip. MAKE SURE YOU REALIGN THE CHIP WITH THE PADS BEFORE YOU STOP HEATING! :!: Now you can go in solder the leads as the other guys mentioned.
Oh.. for 0402s, 0201s, and 01005s (1/2 of a 0201) I use exactly the technique you asked about, since it's impossible to feed the right amount of solder from a roll at those sizes. My other 2 leaded SMT trick is to leave a small amount of solder on ONE of the pads and press down on the part while heating that pad. Make sure the other pad is clean, otherwise you will break the cap off the first end when you try to solder the other end the same way!
Sorry to be so long winded!