Long time is necessary for a reliability test. A theory and the mechanism analysis of the reliability are difficult, too. However, a way of thinking not to need a long-time test is suggested. It is quality engineering.
There are two kinds in the quality of the product. It is a kind to be able to treat by technique of the quality control and a kind not to be able to treat. It is necessary for the latter quality to be established at a development design stage. I comment on technique of preventing it of that purpose at six times.