The switching mode power supply (SMPS) is the key part of a laser beam printer. Its reliability was evaluated and improved by highly accelerated life test (HALT) and accelerated life test (ALT). First, HALT was conducted to evaluate the performance of the SMPS in various environmental conditions and then the problems detected during the tests were modified to meet the expected level of requirement. Second, ALT was conducted to estimate the mean time to failure (MTTF) of the SMPS. The temperature, humidity, electrical load, and voltage were used as stress factors to accelerate the failure of the SMPS. The main failure units were resistors and switching ICs. The test results showed that the acceleration factor was 80 under the stress condition of 80°C, compared to the normal use condition of 25°C.
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