High Voltage Ceramic Capacitors

What is the maximum temperature a capacitor can withstand?

Most current capacitor technologies on the market, such as aluminium electrolytics or film capacitors, are limited to a maximum temperature range of 125oC - 150oC or even lower. To achieve higher temperature ratings, ceramics and tantalum capacitors are used. In downhole electronics, high temperature is usually classified as 150oC and above.

Are high-temperature capacitors reliable?

The lack of reliable high-temperature, high value capacitors has almost certainly limited growth in these newer applications. Most current capacitor technologies on the market, such as aluminium electrolytics or film capacitors, are limited to a maximum temperature range of 125oC - 150oC or even lower.

What determines a high-temperature limit of an electrolytic capacitor?

Largely the formation voltage sets the high-temperature limit. Higher formation voltages permit higher operating temperatures but reduce the capacitance. The low-temperature limit of an electrolytic capacitor is set largely by the cold resistivity of the electrolyte.

How does cold resistivity affect the capacitance of a capacitor?

The higher cold resistivity increases the capacitor's ESR 10 to 100 fold and reduces the available capacitance. The electrolyte is a complex blend of ingredients with different formulations according to voltage and operating temperature range.

How does a higher formation voltage affect the capacitance of an electrolytic capacitor?

Higher formation voltages permit higher operating temperatures but reduce the capacitance. The low-temperature limit of an electrolytic capacitor is set largely by the cold resistivity of the electrolyte. The higher cold resistivity increases the capacitor's ESR 10 to 100 fold and reduces the available capacitance.

What temperature should a capacitor be heated to?

Heating to 200°C for 10 minutes for a second time probably won't ruin your capacitors, but it may reduce their life. The most important, however, is the peak temperature phase, where the temperature goes for a short time (about half a minute) to about 250°C, depending on package volume.