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Shelf life of assembled electronics

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pcm81:
Photography is a hobby of mine and often when discussing high end nikon cameras and lenses the comments get made like "it will outlast you". Which is true at-least about lenses, i own a Nikon lens that is 2 months older than me and unlike me is in a perfectly usable condition. But unlike old style film cameras, the large number of very small components (transistors) in the DSLR cameras got me wondering: what is a shelf life of a package of electronics, such as a DSLR? I am not talking about wear and tear from the use, that varies greatly; i am also not talking about a camera being rendered useless due to new technologies being developed. What i am interested in is the actual expected shelf life from aging of electronics. 20 years? 30 years? More? Less?

james_s:
Electrolytic capacitors tend to have a shelf life, anywhere from several years to several decades depending on the specific type and environmental conditions. Other than that electronic components don't really have a definable shelf life, there is a lot of 40 and 50 year old solid state equipment that still works. Rubber, foam and plastic parts can deteriorate with age.

unknownparticle:
Very difficult to define. As stated above, caps are the component most likely to fail over just time, even in storage, followed by resistors, their most likely failure mode is going high resistance. Semi conductors can also fail in storage, due to package issues. Surface mount components are less reliable than through hole.  All the forgoing is the reason Mil Spec components are produced for the military.  Regarding camera's, I don't use or even have a digital camera, but have many 35mm types.  The earliest of these which have active electronics are from around 1978, and are still working perfectly. However, I have a Nikon F5, a late 90's model that developed an auto focus fault, as in, it doesn't!!  I've never had it repaired as it would cost serious money, it would be cheaper to buy a good used one. It has a huge amount of electronics as it was one of the most sophisticated 35mm film cameras ever produced, so more likely to fail. It isn't the focus motor, as that can be heard hunting. It is impossible to predict when components will fail, but they are spec'd with a theoretical MTBF life, Mean Time Before Failure. Taking the most unreliable, shortest lived component, the electroleaktic crapacitor, they are lifed in thousands of hours when used at max voltage and max temp, the number of hours depending on the quality of the cap. Even then, they can well exceed that theoretical life, or, fail well before!!!

pcm81:
Everything stated above makes sense to me, but there are also additional factors like solder, oxidation etc.
Mil-spec items are actually rated for harsh environment MTBF, they are not really rated for shelf life. I work in aerospace.
Hence is this oddball question. So far we lived in a world where new features of new electronics outpace lifespan of older electronics, hence the upgrade cycle. I am actually typing up this post on a computer that is 11 years old and i used it every day.
Naturally an assembly of components, like pcb, cannot have longer lifespan or shelf life than the individual components used on it; however it would seem like the assembly should have shorter lifespan than shortest lifespan of individual components, since assembly is an item of higher complexity and may be more prone to faults or additive behavior of faults.

That's why i was curious if anyone did any research into lifespan of assemblies.

Kasper:
Flux can cause problems over time if not managed properly during production.  I'm guessing that's not too common in the type of company that makes cameras.  Probably more likely in smaller operations.

I once worked in a messy little company that didn't believe in this or in ESD.  They had problems with both.

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