The PCB Design Magazine

PCBD-July2017

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36 The PCB Design Magazine • July 2017 by Craig Armenti MENTOR GRAPHICS Deriving the physical constraints and fa- tigue issues for a design prior to manufactur- ing is essential to reducing board failure and thereby improving product quality. In harsh environments, fatigue can be responsible for up to 20% of failures. The need to design a reliable product is, of course, not a new concept; how- ever, it has begun to receive greater attention in recent years. Customers have come to expect reliability across the industry spectrum no mat- ter where actual production occurs. Companies that are known to produce reli- able products are rewarded in the marketplace with increased purchases as compared to their non-reliable counterparts. Reliable products have less risk of failure, less field returns and less warranty claims, all of which contribute to higher profitability. It is a given that every prod- uct is expected to fail at some point, however premature failures can be mitigated through proper design with attention to potential issues due to vibration and acceleration (Figure 1). Common Methods of Validation Industry statistics indicate field failure rates of up to 15–20% in the first year of new- ly launched electronic products. Most design teams rely on physical testing to determine reliability issues. Physical vibration and accel- eration testing, also known as Highly Acceler- ated Lifecycle Testing or HALT, provides a clear mechanism to ensure reliability of a product and identify potential failures due to environ- mental factors. This is accomplished by apply- ing a much higher fatigue than the actual prod- uct will undergo, thereby forcing failures and identifying weak spots. The process, however, is costly and destruc- tive, potentially taking months per design to complete. Furthermore, results can vary be- tween testing chambers, possibly concealing accuracy and functional limitations on compo- nents that could then fail in the field. With the high cost and increased time-to-market, only a few prototype designs actually go through physical vibration and acceleration testing. The aforementioned cost and time issues as- sociated with physical testing have resulted in FEATURE

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