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Failure Mode of Chip Capacitor
2021/04/29 03:04:09

SLC single layer capacitor is composed of ceramic medium and metal electrode. Single layer capacitor produced by EXSENSE Electronics Technology Co., Ltd. is mainly used in microwave integrated circuits and optical communication, etc. It plays a role of DC isolation, source bypass, impedance matching, etc. In the working process of the chip capacitor, the failure may occur due to external or internal causes. Generally, there are the following three failure forms:

First, thermal shock failure

In the process of chip capacitor manufacturing, the use of various compatible materials will lead to different coefficient of thermal expansion and thermal conductivity of internal tension, and when the temperature conversion rate is too high, it is easy to appear the phenomenon of thermal shock and rupture. And the failure of thermal shock may cause a variety of phenomena:

(1) Obvious nail-shaped or U-shaped crack

(2) Hidden tiny crack

The difference between the two phenomena is that the latter is subjected to less tension and causes less crack. The fracture caused by the first kind is obvious and can generally be detected in the metalloscope, while the second kind can only be detected by the metalloscope after a certain degree of development.

Second, rupture failure

(1) The rupture caused by the SMT phase

During the SMT phase, the mechanical claws that take and place the single layer capacitor may break due to abrasion, inaccurate counterpoint, tilt, etc. These ruptures are generally visible surface cracks; Surface fracture generally follow the strongest pressure lines and the direction of ceramic displacement.

(2) The rupture caused by the production phase after SMT

PCB cutting, testing, backside assembly and connector installation, and final assembly can cause damage if the solder assembly is twisted or the board is straightened after the soldering process.

Third, the original material failure

Chip capacitor typically has two basic visible internal defects that can damage product reliability:

(1) Inter-electrode failure and bonding wire rupture

The inter-electrode failure and the rupture of the bonding wire are mainly caused by the high gap of the ceramic or the gap between the dielectric layer and the relative electrode, which makes the dielectric layer split between the electrodes and becomes a potential leakage crisis.

(2) Burning rupture

The characteristics of combustion fracture are perpendicular to the electrode and generally originate from the edge or terminal of the electrode. If the rupture appears to be vertical, it is caused by combustion.

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