High-voltage ceramic capacitors can still be broken down. What are the causes of breakdown of high-voltage ceramic capacitors?
There are many factors that cause the breakdown of high-voltage ceramic capacitors, and according to the factors caused by them, the breakdown situation can be divided into: voltage breakdown;Thermal breakdown;Overcurrent breakdown;strong breakdown of electromagnetic field, etc.
One: voltage breakdown.
This is a breakdown condition that high-voltage capacitors are prone to, and in applications it usually manifests as a broken capacitor surface and a crack in the ceramic chip. The reason for this breakdown is that the high-voltage capacitor is not able to withstand the voltage enough. Often, technicians do not have enough control over the voltage margin of the capacitor, which means that if the voltage is lowered a little, or a higher voltage capacitor is used, this problem is solved.
Two: thermal breakdown.
This breakdown usually occurs in high-frequency pulsed circuits. A ceramic high-voltage capacitor with insufficient frequency level is used in a power supply other than the endurance capacity, and thermal breakdown will obviously occur. There is no warning of this breakdown, and it is often a one-hit breakdown, or a few pulses that break down quickly.
The root cause of this problem is that the capacitor itself does not match the Hz level required by the circuit design, for example, a 2 GHz capacitor is used instead of a 2 GHz capacitor. Even lower grade products. The consequence of this is that the capacitor will break down as soon as it is put on the machine. This breakdown is straightforward, because the pulse frequency is so strong that the capacitor is often crushed. Because this is in a very short period of time, the temperature of the ceramic chip undergoes an extremely sharp change, which is caused by the intolerance of the ceramic to high frequencies. This instantaneous heat catches technicians off guard, and it is often easy to misjudge that the voltage is not enough. Because the heating time is too short, no warming phenomenon is found. In fact, the chip is hot at this time.
In the process of practical application, there is a false phase that is not easy to distinguish when the thermal breakdown of high-voltage ceramic capacitors occurs, which requires special attention from engineers. For example, in the process of the product increasing the ambient temperature, when it reaches a certain value, the circuit is suddenly broken. At this time, it is found that the appearance of the capacitor is good, and there are very few breakdown phenomena, and more part, it is that the capacitor does not break down, but only changes the effect. It also returns below its initial value when the temperature decreases.
In the purchase of high-voltage ceramic capacitors, it is also important to choose the original manufacturer with quality assurance. In this way, the breakdown of the ceramic capacitor can be avoided at the source.