Great read(PDF) from KEMET on the design features and screening methods applied to electrolytic and tantalum capacitors to prevent long-term deterioration or sudden unexpected failures.
Wherever electronic equipment is used such as in the home, at work, in-car, or in defense equipment users typically expect perfect reliability while the technology itself should ideally be invisible or transparent. Numerous aspects of today’s components are evolving to realize this goal, from leading-edge nanometre semiconductor process nodes and chipscale packages to improvements in devices such as capacitors.