MLCC Cracking

Gideon Analytical Laboratories received a PCB with possible failed capacitors in several positions. PCBs are used to mechanically support and electrically connect electronic components. They are used in almost every all but the simplest electronic devices, from GPS systems to laptops, from cell phones to microwave ovens. Several MLCC capacitors on this PCB had failed, and the goal of Gideon Analytical Laboratories was to diagnose the cause of the failure.

The objective was to test and cross-section the capacitors for any defects particularly in the terminal area. Each capacitor was cross-sectioned and observed 15 to 20 times under 400 x magnifications during the sectioning process. Pictures were taken during the cross-sectioning to depict the internal quality of the ceramic structure and any cracks (mechanical, knit, Kirkendall voiding or other defects) that may be present. As seen in the picture at the top left, there was an oblique crack in the capacitor.

Although most of the cross sections showed no defects, a few capacitors did have cracks. There was a fine crack which bisects the first two electrodes on the capacitor bottom, as shown in the picture at the top right. This crack may not have caused any noticeable electrical failure. The picture above is taken at 1200x and the crack as it enters the active area becomes progressively finer. This crack was located at the side adjacent to the margin region. As the capacitor was cross-sectioned and this region disappeared, the leakage current immediately disappeared proving that this is the defective spot even though we could not obtain the correct lighting effects to clearly show the crack as it transgressed the electrodes. This is a board flexing failure.

Electronics companies that use Gideon Analytical Laboratories can receive extremely valuable and beneficial information. Imagine knowing whether a device is failing because of a problem in the production process or misuse in some field application. Gideon Analytical Laboratories can take the guesswork out of failures by providing candid and accurate results about how and why devices fail. At Gideon Analytical Laboratories, our goal is to help companies solve problems that help them better prepare for the future.