An accelerated life test is a method for stress testing consumer goods like electronics. The test usually consists of five independent stages: cold step, heat step, rapid temperature cycling, stepped vibration, and combined environmental stress. Although an item may never experience the extremes that the accelerated life test produces, studies have shown that if an item is susceptible in the short term to a certain extreme stress, that it will be susceptible in the long term to that same stress at lesser degrees.
Cold step typically determines the lowest operating temperature of a device, as well as determining the structural integrity of a device at lower extremes. The heat step tests the functionality of a device at high temperatures. This step often is combined with a humidity test to see whether atmospheric water affects the device.
The rapid temperature cycling step usually tests the durability of a product when it is exposed to extreme temperatures. These accelerated life test systems create changes of at least 113°F (45°C) per minute. The temperature fluctuates rapidly between the two extremes to see if this has any effect on the device.
Stepped vibration subjects a device to vibrations at random frequencies between 20Hz and 2KHz. This test aims to show how well a device will hold up during shipping, as well as during heavy duty. The combined environmental stress stage throws it all together and tests the device with vibrations at the temperature extremes.
Before any testing begins, the parameters for the device usually are calculated. For instance, if a team determines that a certain device does not need to receive a high rating against cold extremes, then they typically will note that cold failure does not necessarily mean a failure for the device. The same can apply to extreme heat conditions, as well.
Generally, devices go through the accelerated life test numerous times before they make it to market. The individual components usually go through the testing cycle until all of them make the cut. Then, the assembled device usually is put through the test. If parts do not fare well, they typically are sent back to the design team which then might rework the weak component.
The accelerated life test also can be used by companies to determine their warranty contract. It also is used during the production of a device to make sure the product is consistent. If there is an influx of complaints about inferior products, the company may order an intensive accelerated life test to find the weak point of the device as quickly as possible.
