26 Improving reliability and quality for product success
of materials experiencing stresses, just like mechanical components. The
unit structure of electronic components, including the materials and their
attendant stresses, is not essentially different from that of mechanical
parts, but the shape of the failure rate curve is usually assumed to be dif-
ferent. It is frequently said that the failure of electronic items occurs acci-
dentally, or that failure is random, but that, for mechanical items, there are
few failures within the expected lifetime and many wear-out failures near
the end. Is it true that only wear-out failures occur in mechanical items
and random failures in electronic products? This hypothesis was formu-
lated in