Do unused electronic components expire from old age?

There is a liquidation outlet near my house and they have tons of electronic components for really cheap prices (for instance they have MAX713 battery charger IC's for $1, while online they are around $9).

Most of their stuff is unused, but I think some of it may be really old (like from the 1970's). I'm wondering if these old components are safe to use. Especially the aluminum electrolytic caps (I hear they dry out).

Four concerns in order of importance: 1; electrolytics do dry out, especially if stored hot; 2; batteries, only if I can trace the date code; 3; static sensitive components may have been mishandled/mispackaged to death; 4; component leads become tarnished and difficult to solder (easily fixed).

Until recently, I had an electronics surplus store in my area and it was a great resource. Most of the stock was new surplus from production runs.

Thanks.
About the the aluminum electrolytics -- if you could know the exact production date, and knew they had been in a temperature-controlled room (actually gets a little chilly in the winter) what is the oldest capacitor you would use?

They don't have a 'use by' date, even capacitors from the same batch degrade at different rates although poor storage obviously speeds their demise. I have some capacitors here dating from 1950 which are still in perfect condition but I've disposed of ones two years old because they have lost value. If you need to check them, use an ESR meter. Rising ESR is the first sign of a capacitor going bad, even if it's value seems OK.

Brian.

If you are just experimenting, go for it. If you have a critical application and need the part to not fail....all things have a shelf life! Semiconductors are subject to damage if exposed to the elements, and a plastic package does not protect them forever. Eventually air or moisture will leak in, or the plastic itself will outgas and contaminate the semiconductor. I would probably not try to use semiconductors more than 10 years old for that reason.

Aluminum electrolytics can be "rejuvenated", but yes they do die after a while. Older tantalum capacitors can fail rather spectacularly. Old circuit boards are hard to solder too unless it is just a thin layer of surface corrosion which can be cleaned up with a wire brush.

Ceramic capacitors are basically rocks, and will last ~forever. Old solder will have the flux dry out in the middle, and will not work too well.

But with the price of components being so high today, the only way an experimenter can get by is to buy used components. Some of the better deals are kits of components, like a kit of every common leaded resistor value in a set of drawers, a partial reel of 0.1 uf chip capacitors or 4.7 uf tantalum capacitors, a small box of cut reel pieces of chip resistors (50 of each value). Stuff like that just keeps on giving day after day!

Don't get tempted to buy any dangerous stuff! You do not want a big kit full of cadmium plated screws for instance, as the cadmium dust is toxic! Too much lead plated stuff around the house is a bad idea. Asbestos is a bad thing to breath in. Common solvents from days gone by are now considered carcinogenic. etc etc.

Used tools can be a great deal too. Pick up a couple used weller controlled temp soldering irons for $15 each, but some new tips and sponges, and you are good to go for a $400 savings! Used test equipment can be a good deal too if it is in working condition. For a few hundred bucks you can get a quality tektronix scope, a couple power supplies, and a function generator.

Wow, thanks for all that info.

Beware of computer motherboards in particular. If you are trying to make a cheap linux box, The capacitors fail frequently due to age and//or heat and many times they fry the cpu and memory or any AGP, PCI, or ISA cards (video, NIC, modem)

There is possible to predict life cicle of determined component, based on MTBF estimation.
One of te most used model is that :


Notice that it consider enviroment conditions ( temperature, vibration, etc... )

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The document (Mil-Handbook 217F) Reliability Predictions of Electronic Equipment noted in the MTBF analysis dates back to 1991 with last update 1992. That is nearly 20 years ago. Do the calculations and assumptions really hold up? The largest microprocessor cited is 32 bits but we know that is small now, and memory devices that hold 1 million bits is tiny. I have more than that in my cable box or digital clock. Very large scale integration gate count of 60,000 was big in its day.
Moore's law has made obsolete this document about a few months after publication. But it usually tales the government so long to sanitize this doc. to make it politically correct, it would have been relevant when probably originally written in the 1980's.

montyw47,

Although this document be old, it is still referenced and is very trustable.
In absense of other models, we can estimate them, just extrapolating values, due most growth linearly.
Note also the case you mentioned is covered at other section, changing the model.

Could you sugest other chart to predict MTBF ?

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Some time ago I bought a large lot of old IC's, many from the 1970's, still in their original tubes. I soon noticed that many of them had tarnished legs, but only the ones near the ends of the tubes. This was especially true of the Texas Instruments parts. It turns out that back then the pins were plated with silver, which reacted with the sulfur in the tube's rubber endcaps to form a black tarnish.

Some other things to keep in mind:

1) NVSRAMs contain lithium cells that age as they sit.
2) SMD parts that have been improperly stored may explode while being soldered.
3) Electrolytic caps are a crapshoot, Definitely stay away from surplus Taiwanese caps. Capacitor plague - Wikipedia, the free encyclopedia