Thermal-Shock Testing and Fracturing of MLCCs Under Manual-Soldering Conditions

The fracturing and failures of multilayer ceramic capacitors (MLCCs) after manual soldering onto printed wiring boards are often associated with a soldering-induced thermal shock that results in substantial mechanical stresses in the parts. Recommendations and guidelines for safe soldering conditions are well developed and documented; however, there is a lack of adequate testing for the selection of MLCCs that are robust enough to sustain stresses related to manual soldering. In this paper, various lots of X7R-type material MLCCs with different size have been subjected to three types of thermal-shock testing: terminal solder-dip test, ice-water test, and liquid-nitrogen drop test. The electrical characteristics of the parts were measured through various test conditions to determine critical temperatures that resulted in fracturing and electrical failures. Optical examinations and cross-sectional analysis were used to confirm the presence of cracks. The mechanisms of fracturing, factors affecting crack formation, and the effectiveness of different thermal-shock methods are discussed.