43Chapter three: Novel concepts of reliability technology
the current model. Meanwhile, according to the veried results,
*
Pecht’s
law states that the failure rates of microcircuit devices for digital systems
decrease by about 50% every 15 months. Therefore, the duration of the rel-
evant period in Moore’s law cannot be shorter than that of Pecht’s law.
†
3.4 The BX life target setting as a durability index
Using the mean time to failure (MTTF) as a lifetime index leads to misun-
derstanding, whereas the index of BX life more properly reects the real
scenario of the life of an assembled product.
‡
The last section explained
that the lifetime target of a unit incorporated into a more complex product
should be equal to or longer than that of