Applications Recent advances in material technology and design have allowed multilayer ceramic capacitors (MLCCs) to extend beyond replacing electrolytic capacitors in output filtering applications.
Avoiding failures in ceramic chip capacitors, also known as multilayer ceramic capacitors (MLCCs), is strongly driven by the ability of the designer, both electrical and mechanical, to follow guidelines based on an understanding on how surface mount ceramic capacitors fail.
Failure mechanisms for ceramic capacitors are presented and the drivers for failure occurrence, mechanical, thermal, chemical, and electrical, are tabulated. The influence of Pb-free solder on each driver is then analyzed, with the subsequent output changes in current design guidelines with justification when appropriate.
In every electronic assembly line where ceramic capacitors are used and printed circuit boards are depaneled the quality risk “flex cracks” is widely known. Unfortunately flex cracks in “cercaps” always extend under the metal terminations of the capacitors and electrical tests only reveal about 1% of the affected parts.
In the course of failure analysis it is helpful to know that most of the time not only the failed ceramic capacitor shows a crack pattern but all the surrounding cercaps as well. Well-founded knowledge of different crack patterns and failure modes also allows us to discover unsafe bending and warping lines on the PCB.
The most probably root cause is related to a potential leakage of a ceramic capacitor. This capacitor had to be replaced as a result of a non-compliance detected during manufacturing and testing phase. For the repair process, the capacitor was assembled using direct wiring soldering process.