reuse - Using recycled components

To what extent and which components can be salvaged from 5-15 years old electronic devices? In other words, what is feasible to dismantle for hobbyist use and what is not? Especially, is it ok to reuse surface-mounted ICs?

My own experience tells, that resistors, transistors, small capacitors survive quite well, but I am not sure about small diodes, small and surface-mounted electrolytic capacitors, crystals. Also, I have bad experience with recycling connectors (pins get out of plastic case).

Somewhat related, how to check non-trivial components? Do some of them loose precision a lot?

Maybe, there is some specialized web resource on the topic and or guides.

UPDATE: I am really interested in an answer from persons, who had more or less extensive practical experience with recycling different kinds of components. Personally I do not recall anything failed because of thermal impact of desoldering (but I have no experience with SMDs). And this makes this question even more interesting, because answers so far are discouraging the practice.

Answer

So much of this depends on the quality of your desoldering technique. I have personally found that, when it comes to removing components, very short exposure to high heat is preferable to prolonged exposure to low heat. That being said, I would NEVER re-use an aluminum electro - (if you MUST, at least check it with a reliable ESR meter first). Film caps take desoldering well as long as the barrel of the iron is kept away from the cap's body.

Metal film and wirewound resistors can reliably survive desoldering and keep their value within spec; carbon films and (especially) carbon comps will sometimes "open up" in value to a small degree - (sometimes this is acceptable, sometimes not; check them with an ohmmeter before using).

I've not had any problems desoldering diodes that are designed to take any degree of heat (such as DO-41's, DO-35's, DO-204's, etc.) Also, these are usually mounted "off-the-board" slightly. I've never bothered w/SMD diodes or small signal (1N914/1N4148) diodes as they're extremely cheap new.

But you asked about SMD chips in particular. I can only impart my personal experience, which is as follows:

SOT's and SOIC's - Very doable, but having one of those threaded IC desoldering tips for your iron (which heats all pins simultaneously for easy removal) is a major plus.

SSOP's - Hit or miss. I've had many successes (and a few failures), but I generally don't bother unless it's something I really need immediately.

QFP's/LCC's and the like: Forget it!

Hope this helps.