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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.

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  • \$\begingroup\$ My general guideline would be: don't recycle at the component level unless it has wires that can be cut. Desoldering a non-wired component results in let's say (let's be optimistic) 5% failures? That means that a circuit with 10 such components has a success rate of 60% ... \$\endgroup\$
    – Wouter van Ooijen
    Commented Jul 10, 2013 at 15:14
  • \$\begingroup\$ Please, clarify, what do you mean by non-wired component? Surface mounted? Too short legs to be inserted somewhere else? \$\endgroup\$
    – Roman Susi
    Commented Jul 10, 2013 at 15:22
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    \$\begingroup\$ I'd say don't expect reliability out of any component you de-solder - the heat damage & physical stress can easily shorten lifespans even if no obvious damage occurs. Remember too - that component may already be some way through its expected service life! All that said - I've re-used all sorts either when needs must or when just idly fiddling, and almost anything can be re-used if you have the capability to remove it intact. \$\endgroup\$
    – John U
    Commented Jul 10, 2013 at 15:24
  • \$\begingroup\$ Roman: I meant: if you can remove it by cutting wires it is probably OK, if it requires soldering I would not trust it. @John: the devil is in your last words: "if you have the capability to remove it intact" ;) \$\endgroup\$
    – Wouter van Ooijen
    Commented Jul 10, 2013 at 15:53
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    \$\begingroup\$ @WoutervanOoijen - The devil is always in the detail! I would add that the activity of trying to remove components intact is quite good practice at (de)soldering & learning what sort of damage you can cause & how to avoid it. That is when you are just doing it for fun/interest and don't really care if the component survives or not. \$\endgroup\$
    – John U
    Commented Jul 10, 2013 at 16:24

3 Answers 3

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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.

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  • \$\begingroup\$ This matches my experience too, even though I usually use rework station / vacuum desoldering pump. Thanks for the ESR-meter reminder. \$\endgroup\$
    – Roman Susi
    Commented Aug 28, 2013 at 3:29
  • \$\begingroup\$ With hot air, I'd not hesitate to salvage a known QFP if I had a need for it, in the sense of not having another on hand. Having done it once in the middle of the night with an iron, braid, and music wire (so I could put it back down in the right orientation!), doing it with a rework station is comparably no big deal. \$\endgroup\$
    – Chris Stratton
    Commented Aug 28, 2013 at 4:46
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I usually keep a couple of boards assembled as source for test parts, desoldering, measuring, sorting and labeling would be a huge waste of time.

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  • \$\begingroup\$ So, are you proposing to store old boards in assembled state instead of at least partially put components to proper places? How to find component quickly then? \$\endgroup\$
    – Roman Susi
    Commented Jul 11, 2013 at 3:31
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    \$\begingroup\$ There are fairly few components which would be worth the time to speculatively remove, vs simply speculatively stocking in new form. But if you get stuck on a project because you need a surface mount encabulating modulator right now and you have some sense of what is in your junk box, you likely know what types of boards might use one. I did a form of that today, transplanting a crystal from last week's prototype to today's, because we ran out and the reorder won't arrive until tomorrow. \$\endgroup\$
    – Chris Stratton
    Commented Jul 31, 2013 at 4:20
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Personally I wouldn't do it. Outside of stripping heatsinks and other hardware, you run the risk of transplanting heat or physically damaged components into the new circuit.

Perhaps socketed ICs are another exception.

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