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Shelf life of semiconductors held in a storage area for 26 years question — Parallax Forums

Shelf life of semiconductors held in a storage area for 26 years question

UnknownUnknown
edited 2009-11-04 16:39 in General Discussion
My dad stored some semi-conductors in a storage area for about 26 years.· The storage area was not climate controlled and some things melted and other parts look okay.

I plugged in a flood light and it didn't last half a day.

Some of the things like wires, solder and terminal connectors I will keep.· Should I try everything else or should I say enough is enough and give up with the capacitors, resistors and other things and just go with new?· If something looks okay, will it give me a true voltage or could its characteristics change over time?



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Comments

  • kwinnkwinn Posts: 8,697
    edited 2009-11-04 16:21
    What to try or toss depends on the item and how you intend to use it.

    Electrolytic caps - toss - The electrolyte dries out and even if they seem to work now they may not work for long.

    Other capacitors, Resistors, IC's, Transistors, Diodes, Zeners, Bridge rectifiers, Relays, etc search the internet to see if you can find data sheets for them and keep them if they may be of any use. Test them before soldering them in a circuit.
  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2009-11-04 16:34
    Depends on how hot the semi-conductors got in storage. Generally "today" the metal migration rules are set for 10 year 125 Deg C operation which basically is a derating factor that can be adjusted for "special case IC's". If you think of metal as a fluid ( a very slow moving fluid ) with a specific flow rate due to gravity and temperature, then eventually metal wires within an IC will bleed into one another and cause a short. The more current (HEAT) that you put into the chip will shorten the time required for this failure event to happen. The CMOS process in 1983 was much bigger than it is today and metal migration while it still did exist may not be as much of a problem with an older chip as it would be with a chip made today placed in storage until 2035.

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    Beau Schwabe

    IC Layout Engineer
    Parallax, Inc.
  • mctriviamctrivia Posts: 3,772
    edited 2009-11-04 16:39
    bigger question is how much would it cost you to buy new stuff? some things like surface mount resisters and caps are $10/5000 other things are a lot more expensive.

    *Aluminum wire recycle it will not be worth your time to clean and you can make a little money on the raw metal.
    *Copper wire will be fine though insulation on cheap older wire can be a pain to take off.
    *Resisters, Caps - odds are the parts are cheap enough to buy to not be worth your time and effort to test and more time and frustration to trouble shoot later if a bad one gets into a circuit.

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