Environmental Testing – Why?
Since today’s consumers and businesses expect totally fault-free operation and uninterrupted service, tests must be devised in order to guarantee performance. Environmental testing is part of the testing that is conducted to determine a component’s ability to perform during, or after exposure to a specific environment.
These tests are designed to assess the basic design of the device as well as the fabrication methods and materials used. Passing these tests is an indicator that the device will indeed be robust enough to provide long-term reliability. In addition, environmental tests assist in determining a device’s safe and proper operation and its operational limits.
Mismatch of thermal coefficients of expansion of materials used in electronic and optoelectronic components are among the leading contributors to the failure of equipment exposed to extreme temperature variations. Repeated exposure to cyclic temperature variations can fatigue joints of different materials, and cause them to fail.
Conducting temperature cycling testing on these components will assist in determining
1) the existence of thermal coefficient mismatches and
2) the sensitivity of these mismatches to repeated temperature excursions.
Temperature cycling is performed in chambers that control number of cycles, dwell times, transfer times or ramp rates, and temperature extremes. Oftentimes, component manufacturers perform temperature cycling experiments far beyond Telcordia, JEDEC, or MIL specifications to ascertain eventual failure modes. In particular, temperature cycling to failure will be performed on a limited sample for information only.