MDT is capable of screening the diodes when the customer requires that the diode meet performance specifications at an operating environment which is different from that in the catalog. The time and temperature are chosen to accelerate any incipient or latent defects. Any weakness in the bond between the chip and the underlying package will result in bond breakage. The test is done in a centrifugal chamber in such a way that there is a force trying to pull the straps or wires away from the semiconductor chip. The normally used acceleration is 20,000 g's.
Bond pull tests in sample devices are more reliable.
Microwave semiconductor diodes are not normally subject to mechanical shock tests because of their small mass. Again, because of the small mass the microwave semiconductor devices and the associated bond wires or straps are not tested for bond integrity by mechanical vibration tests. However, in certain applications such as in missiles where microphonic noise may pose a problem during launch, operational tests may be conducted under mechanical vibration. Microphonic noise may be caused by the strap or wire movement under vibration causing frequency modulation of the oscillator. Such tests are time consuming and very costly.