Failure analysis of miniaturized multilayer ceramic capacitors in surface mount printed circuit board assemblies

Abstract

New failure analysis results of miniaturized multilayer ceramic capacitors (sizes 0402, 0603, 0805 and 1206) which have been subjected to various degrees of thermal shock up to 450°C by ice-water or dry ice quenching are reported. The thermal shock resistance of 0402 multilayer ceramic capacitors was found to be about 400°C and considerably better than those of the larger ones. Microstructural and layer-by-layer insulation resistance analyses have clearly identified the physical locations responsible for the electrical leakage of defective capacitors. Further, no evidence of silver migration as a dominant failure mechanism has been observed for any of the defective capacitors under usual operating stresses. Comparisons ofI–V characteristics for multilayer ceramic capacitors quenched by ice-water and dry ice confirm that water plays a significant role in causing electrical failure at nominal bias. Comparisons with results obtained from practical surface mount printed circuit board assembly of mobile telephones is discussed. From these, failure mechanisms are proposed to explain the failure of miniaturized multilayer ceramic capacitors under normal service conditions.