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42 PCB007 MAGAZINE I OCTOBER 2023 Feature Article by Reza Ghaffarian JPL NASA Editor's note: is excerpt was taken om Chapter 60 of the Printed Circuits Handbook, 7 th Edition, edited by Clyde F. Coombs and Happy T. Holden. Reliability Testing Methods Almost every reliability test program must solve the problem of determining whether an object is reliable in a time that is much shorter than the expected use period. Obviously, one cannot spend three to five years testing a per- sonal computer that will be marketed for an even shorter time span or 20 years testing a mil- itary system. Depending on the failure mech- anism, there are two approaches that may be combined: 1) accelerate the frequency of the occurrence that causes failure and test the abil- ity of the object to survive the expected num- ber of events; or 2) increase the severity so that fewer occurrences are needed. Drop tests that simulate shock during transportation are an example of the first approach. Since the time between drops does not affect the amount of damage caused, a lifetime of drops can be con- ducted in rapid succession. However, the effect of temperature and humidity on corrosion over the lifetime of the product can be tested only by increasing the temperature, the humidity, Reliability of Printed Circuit Boards