Capacitor porcelain sleeve abnormality

What causes a MLC capacitor to fail?

These arise from mismatches in CTE, both between the capacitor and the board on which it is mounted and between the different materials which make up the capacitor. The MLC is constructed of alternate layers of silver/palladium (Ag/Pd) alloy, with a CTE of around 20 ppm/°C, and ceramic with a CTE of 10–12 ppm/°C.

What happens if a ceramic capacitor falls out?

In severe cases, the body of the capacitor may even fall out, leaving just remnants of ceramic surrounded by termination and solder joints. Fortunately, improvements in ceramic technology have reduced the incidence of both types of crack, at least as far as well-made components are concerned.

Are multilayer ceramic capacitors reliable?

Multilayer ceramic capacitors (MLCs) have become one of the most widely used components in the manufacture of surface mount assemblies, and are inherently very reliable.

What happens if a capacitor cracks?

After a number of temperature excursions, for example due to circuit operation, the crack may propagate (Figure 3), creating an open-circuit device. In severe cases, the body of the capacitor may even fall out, leaving just remnants of ceramic surrounded by termination and solder joints.

Do chip ceramic capacitors need to be marked?

Chip ceramic capacitors are usually unmarked, because of the practical problems of doing this. However, some end customers, particularly in the automotive industry, prefer capacitors to be marked, so that they can have visual assurance that the correct component has been fitted.

What causes elliptical cracks on a capacitor?

In severe cases, when a large surface mounted capacitor has been subjected to a sudden thermal shock, a clearly visible elliptical crack may form on the upper surface of the chip (Figure 1). This is primarily due to the tensile forces exerted by the terminations.