Multilayer Ceramic Capacitors: Mitigating Rising Failure Rates
The multilayer ceramic capacitor (MLCC) has become a widely used electronics component both for surface mount and embedded PCB applications.
Materials Tech
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Authored By:
Dock Brown
DfR Solutions
Summary
The multilayer ceramic capacitor (MLCC) has become a widely used electronics component both for surface mount and embedded PCB applications. The MLCC technologies have gone through a number of material and process changes such as the shift from precious metal electrode (PME) configurations which were predominantly silver/palladium to base metal electrodes (BME) dominated by nickel.
Each of these changes were accompanied by both quality and reliability problems. The MLCC industry is now in the midst of an unprecedented set of challenges similar to the Moore's Law challenges being faced by the semiconductor industry. While capacitor failures have historically been responsible for a significant percentage of product field failures (most estimates are ~30%) we are seeing disturbing developments in the low voltage (<250V) commodity part infant mortality and wearout failure rates.
Conclusions
Field failures have been confirmed for MLCC applications where DC leakage fell substantially below the manufacturer's datasheet specification in 14 months, far below the 5 to 8 years projected in [11]. One conclusion in that 2010 CARTS paper was, "given the complexity of today's electronic devices and the reduced reliability margins of high CV capacitors, designers must pay special attention to reliability requirements of their system and the long term reliability of the capacitors" To mitigate rising MLCC failure rates, that was advice worth heeding in 2010 and remains valid today.
Initially Published in the IPC Proceedings
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Comments
No mention in the report about the improper rework of the ceramic chip caps causing or contributing to the failure rate increase. Replacing them with a soldering iron or soldering tweezers crack them internally and shorten their life. IPC had a video about 30 minutes long discussing how to rework/replace them after initial assembly.
Bruce J Sander, EAE Sales
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