Improving the reliability of a newly-designed mobile phone by environmental tests and accelerated life tests

The auto-fold motor is the key part of the auto-fold mobile phone. Its reliability was evaluated and improved for the newly manufactured mobile phone. Two kinds of tests were performed for this purpose. First, environmental tests such as high/low temperature operation tests, high/low temperature storage tests and thermal shock tests were conducted to evaluate the performance of the motor at various conditions and then the problems detected during the tests were resolved to meet the expected levels of requirements. For example, the noise of the motor was decreased by changing the grease type. The wear-out of the cam shaft and hinge housing was also decreased by upgrading the quality of the raw material. Second, the accelerated life tests (ALTs) were conducted to measure the mean-time-to-failure (MTTF) of the motor. The temperature and the voltage were used as stress factors to accelerate the failure of the motor