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Originally Posted by Butcher
A TEC won't flex much as the surfaces are ceramic which will shatter or crack if you try to bend it too much.
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That they will.
Another cause of failure is bowing of the hot/ cold plates. If a unit is not properly clamped the majority of the pressure exerted on the TEC will be around the edges somtimes with no pressure at all in the middle. If some of the p-junctions have nowhere to transfer heat to because of little or no clamping pressure they will not perform well and may self destruct.
Yet another cause of failure is stress fracturing. This is more likely to occur in larger TECs that are cycled. The clamping requirements of TECs are much higher than CPUs etc. Typical mounts are designed to exert about 300 psi on the TEC. A copper mount will not expand and contract at the same rate as the device and under 300 psi the TEC cannot move on it's own. This is why many maufacturers do not produce the mondo 220w + TECs used a lot on computers, as a larger TEC is repeatedly heated and cooled the MTBF from stress is lower than with 2 smaller TECs with the same combined output.