I understand that many components, such as electrolytic capacitors (Do electrolytic capacitors have a limited shelf life?), have a limited shelf life if not used. Other components, such as carbon resistors tend to change values over time while sitting on the shelf.
What I would like to know is if ICs also have a limited shelf life and if so, do some types suffer more than others?
ICs as such dont have a shelf life, like milk or so. They do age on the shelf, though, but generally not as fast as when in use. What happens is you have a rising probability of ICs being dead when unpackaged, or dying earlier when used.
Oxidation, radiation (both natural and man-made), and chemical degradation of the dielectric, and probably several other aspects, degrade the ICs over time.
The effect of these influences largely depends on the manufacturing process and the quality of the IC. A well made IC may be less prone to oxidation, for instance. Older ICs (aka larger structures) have more material to be eaten away. Some ICs have dielectrics than can be more prone to aging. Modern ICs seem to be built with thinner, but more robust dielectrics.
All told, the ageing through technology means more. I do have perfectly working 74ls00 that is over 30 years old in an apparatus that is mostly turned off. Would I use it to build something today? Probably not.
But then again, from a museum perspective, it is quite important to know how to preserve ICs: Dry with a desiccant, in a metal container which is not radioactive seems to be the best bet.
ICs have a limited shelf life, but that has little to do with the die. It's rather about the solderability of the pins. These are coated and the coating will oxidize with time, which would result in poor soldering. For production quantities your ICs may come in vacuum packaged trays with a "use before" date on them, usually a few months to a year in the future.
It depends in the IC packaging , if the IC is MSL1 (Moisture Sensitivity Level 1) , the shelf life is unlimited. See JEDEC Standards (020C)
As @posipiet said, no. However BGAs and some other packages do need to be kept dry. That's why there is descant in the bag. Once the bag is opened, if you wait too long you need to bake them first.
An over looked type of special chips (or chip modules) that other people haven't listed are ones that have other "things" integrated inside of them, such as: 1) battery inside some battery-backed SRAMs, 2) crystals inside real-time clocks, 3) Opto-Isolators (not sure if they age over time on the shelf). In the case of the battery, the obvious draining of the battery over time is an issue, and the case of the crystal is the aging of the crystal may change over time thus losing precision.
ICs are made out of a piece of monocristalline silicon that has been doped P or N in selected adiacent areas in order to make junctions. Typical dopings are of one "foreign" atom in 1000 Si atoms. If you take a 1 liter of water in a jar and put two drops of color (say one red and one black) after a certain amount of time the color will diffuse all over the jar and a sort of uniform brown color will be seen. That amount of time goes linearly with time and exponentially with temperature. So if you keep your spare ICs in -18°C refrigerator their shelf life will be exponentially longer.
