On 12/03/2014 02:19 PM, Ron Bean wrote: > Jon Elson <[email protected]> writes: > >> One other place the military screwed up, is Tantalum >> capacitors. These have the >> bad characteristic that they can be VERY reliable if used >> CONSTANTLY. That means >> either on all the time, or used every few days. But, make >> something with >> tantalum caps, test it rigorously, and then put it in a >> supply depot for a couple >> years, and you will almost CERTAINLY find the caps short out >> and blow (as >> in fire and smoke) when you then put it into use. > > Does that mean that unused tantalum capacitors have a limited > shelf life? > > Also, Wikipedia says that some of them used to have a liquid > electrolyte, does that affect the shelf life? > > Yes, apparently the "wet slug" design is the one that has this failure mode. I don't KNOW about the new-old stock thing. My experience is with built equipment, which presumably was run for at least a functional test before going into storage. It may apply specifically to gear that has run in the field for thousands of hours before going into storage, I just don't know. I DO know that I have run into this a lot, and replaced shot tantalum caps in gear I picked up surplus.
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