I would think the thermal shock of the chips hitting the hot water would be a failure mechanism. Hot air and hot water are different things, even at the same temperature. The thermal resistance of a water to ceramic (or plastic) junction is much, much lower, than one with air, so during the first seconds of the wash cycle, the chips go from ambient temperature to something rather high. Lots of stress results, especially if only some of the chip's package gets wet. Preheating the boards would help reduce the shock greatly, but home dishwashers do not do that (not a good idea to cook the food onto the plates before trying to wash them!).