Internal MLCC cracking can result in serious failure modes. If ceramic capacitors are subjected to severe mechanical stress, a bending crack may occur. This crack can run through two or more electrodes of opposing polarity and result in a short circuit. Typical bending cracks are shown below. In the worst case scenario, these short circuits may lead to the MLCC overheating and catastrophic failure.
Standard termination construction may result in ceramic cracking during PCB bending, vibration, Depanelizing, etc.
Failure Mode Type 1
The failure mode results from PCB bending forces. These cracks may not be visible on the MLCC surface. Cross sectional analysis is required to identify these internal cracks.
Failure Mode Type 2 (wetting greater than 2/3 of thickness)
MLCC cracking frequently occurs during the circuit board depanelizing process. The root cause is knife (blade) vibration during the process
Holy Stone has developed the “Super Term” Series (TX suffix in the part number), which incorporates a “cushion layer” in the termination structure. This construction effectively absorbs external forces, reduces the incidence of cracking and improves overall product reliability.
SuperTerm product applications include: high temperature automotive, power circuits and other critical end products with extreme processing conditions.
During destructive bending test, the PCB is subjected to bending until capacitor failure. With superterm there is no cracking damage in the ceramic.
Superterm effectively prevents ceramic body cracking during extreme mechanical stress as simulated by this test. Superterm failures resulting from destructive bending test occur in the OPEN mode and not the short circuit mode typical of standard termination failures. The SuperTerm cushion layer material is a ”polymer silver” material and can be seen in the above photo.