Reliability Assessment of Electronic Devices - A Case Study of Connectors Applied to Telecommunication
Date Issued
2009
Date
2009
Author(s)
Chen, Yao-Chung
Abstract
The steady-state failure rates of electronic products applied to telecommunication are frequently estimated based on Telcordia SR-332 Reliability Prediction Model. Its basic assumptions are that product lives follow the exponential distribution and failure rates are constants. Although this approach provides us an easy way to estimate the failure rate, mean time to failure (MTTF) and other quantities related to product reliability, it may not be able to reflect complicated environmental conditions a product may be subjected to. In practical applications, products are affected by many environmental factors causing reliabilities predicted by the model inconsistent with characteristics of the products. Therefore, in the present study, Failure Mode and Effect Analysis (FMEA) and Fault Tree Analysis (FTA) are used to identify the most relevant failure modes of a particular electronic product - a two-mm hard metric connector. Based on results from FMEA and FTA, a series of accelerated test and durability test are designed and performed for the studied connectors. Detailed reliability analyses are carried out. The result shows that the activation energy is 0.26 eV for pins of this type of connector. Among the fitted probability distribution functions, the pin life follows the lognormal distribution the best, and its MTTF is 69,734 hours under the condition of 40 ℃ if Arrhenius model is adopted. If Eyring model is considered instead, the lognormal distribution is also the best fit to the tested data. Its MTTFs are 74,634 hours under the condition of 40 ℃, and 70,725 hours under the condition of 40 ℃/30％ RH, respectively. The above results show that the pin life does not follow the exponential distribution and the failure rate is not a constant as reflected by Telcordia model. If Telcordia SR-332 Reliability Prediction Model is applied, the failure rate is found to be 1.79 FITs (Failures per Billion Device Hours), which has a MTTF of 558,659,218 hours. As for the plug-in-and-out durability test, the result from analyzing the test data indicates the pin life may be fitted by a lognormal distribution, and its MTTF is 41,771 cycles. In summary, with its rather strong pins, the tested and analyzed type of connector is quite reliable.
Subjects
Failure Mode and Effect Analysis (FMEA)
connector
accelerated test
durability test
activation energy
Type
thesis
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