Highly Accelerated Life Test
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A Highly Accelerated Life Test (HALT), is a stress testing methodology developed by Gregg K. Hobbs. It is commonly associated with electronics and is performed to obtain information about a product's reliability. Individual components, printed circuit boards both populated and unpopulated, and whole electronic systems can be subjected to different HALT tests. Testing is typically performed on a statistically significant sampling of the product which is governed by many factors including the number of samples available, cost, type of stresses applied, and physical size. For example, component manufacturers can typically test thousands of individual components at one time.
Individual components such as resistors, capacitors, and diodes, printed circuit boards, and whole electronic products such as cell phones, PDAs, and TVs, eventually fail under consumer or end-user stress levels. For example, a typical consumer-owned cell phone will not likely be found in temperatures above ambient, dropped more than about once a day from only a few feet off the ground, or subjected to extreme vibration. Ideally, when a product's reliability is investigated, it is tested under the end-user stress level and tested until the product has failed. Statistical data from this ideal test will be directly correlated to the real world. However, manufacturers are driven by consumers who want to purchase reliable products that last years before failure under end-user stress levels. Therefore, testing under these end-user conditions is typically not feasible due to the length of time the test would take for all of the products being tested to fail.
A highly accelerated life test, as its name implies, speeds up the time until failure of the product. This is accomplished by increasing the test stress levels. The data obtained must then be correlated from the increased stress level to the end-user stress level.
