Gideon Analytical Laboratories received several PCBs with MLCC capacitors mounted near the circuit board edge. The capacitors had a polyurethane conformal coating passing class 2 IPC-A-610 inspection. Several of the capacitors had less than 3000 ohms leakage current when measured on an IR meter. The coating was removed and the samples were potted and cross-sectioned for further analysis. The capacitor shown is typical of a lot of failures.
These are flex cracks caused by PCB flexing or bending. These types of failures most generally do not show any signs of stress on the outside margin area and, therefore, cannot be identified visually under the microscope. This failure is clearly a handling issue associated with installation.
Gideon Analytical Laboratories can identify many different causes of failures: Components (end of life, wear out mechanism in components, electrical stress, package seals, processing induced failures, seal), manufacturing (assembly, process, testing, PCB layout), design (improper component, layout, wrong component value, design flaws, better design, better failure rates), process problems (material incompatibility, physical stresses caused by materials, residual materials left on PCBs, cleanliness issues), environmental (outside sources of contaminants that are inherently not compatible with the solder mask, copper, lead metallurgy, moisture, temperature). When your product fail, and you want to know why, call us.