A composite material is provided, which has a low thermal expansivity, a high thermal conductivity, and a good plastic workability, which composite material may be applied to semiconductor devices and many other uses. The rack and tray assembly comprising a folding frame structure having left and right legs and a tray support assembly situated and mounted thereinbetween for supporting at least one tray. A first filter may receive the quality value and produce a first filtered quality value, and a first comparator may compare the filtered quality value to a threshold and produce a fault value if the first filtered quality value crosses the threshold.