Contamination and Moisture on MLCCs

Gideon Analytical Laboratories received a printed circuit board (PCB) with suspected failing multi-layered ceramic capacitors (MLCC). Multilayer ceramic capacitors are fixed value capacitors in which ceramic the material acting as the dielectric. It is made up of two or more alternating layers of ceramic and a metal layer acting as the electrodes. There are various types of materials that could function as the dielectric in a capacitor, for example, glass, porcelain, paper, or mica. Each PCB has four suspected failing MLCCs, and the goal was to determine the cause of these failures.

Gideon Analytical Laboratories performed expert electronic failure analysis on these MLCCs. First, they were electrically tested regarding moisture. The four respective MLCCs are labeled, C1, C2, C3, and C4. These are the results:

MLCC ohmsNewBad PcbMoisture Test on badBakeWater immersionBakeRemove Caps
C115G7.4G10G20G69M,139M,183M, 408M, 3G, 11.6G>15G14.7G
C215.2G15G228M16.8G295M, 428M, 532M, 556M, 610M, 638M>15G283K
C315G13.513.6G15.2G751M, 856M, 933M, 1G, 1.2G, 1.3G>13G13.3G
C417G14.715G15.3G594M, 698M, 796M, 896M, 981, 1.1G>12G15.3G

C1 had no voids in the conformal coating. Unfortunately, C2 had a void in the conformal coating next to the side, which went all the way to the bare board. The SEM-EDS-XRF analysis was used to further analyze these MLCCs. The spectra of the backside of C2 was very complicated; the ceramic was barium titanate, the solder was tin/lead with bismuth. The silicone coating was siloxane, oxygen, and aliphatic alkanes. After SEM-EDS-XRF, C2 was cross-sectioned. In conclusion, Gideon Analytical Laboratories identified the cause of this failure as contamination what is moisture because of the breach in conformal coating.

At Gideon Analytical Laboratories, we know what it takes to solve almost any electronic failure. To your electronics company, a failure is like moisture inside your MLCC; you don’t want it. Let us put the decades of experience, state of the art analytical equipment, and our motivation to succeed to work for you. Do you have problems?  We have solutions. Call Gideon Analytical Laboratories today.

C2 backside, analyzed by SEM-EDS-XRF

C2 backside, analyzed by SEM-EDS-XRF

C1 no voids in the conformal coating

C1 no voids in the conformal coating

C2 Spectra

C2 Spectra

Side of C2

Side of C2

Other side of C2

Other side of C2

Cross Section of C2

Cross Section of C2