[Webinar Recap Part One] High Voltage MLCCs in Comparison to Safety MLCCs

In a recent webinar, Division Manager Pierre Lohrber explained the comparison of MLCCs for high voltage and safety applications.

Pierre is responsible for the capacitor business unit worldwide for Wurth Electronics. He has a background of more than 25 years of experience in the electronics business, as well as supply chain management, and supply chain risk management experience. His expertise gives him an overview of the market as a whole, including knowledge for different technologies of capacitors.

In today’s recap of Pierre’s webinar, we will cover important definitions of which you should be aware and provide an in-depth overview about the usage and comparisons of MLCCs.

Ceramics Class 1 & Class 2

To help differentiate the MLCCs, we have various types of software classes.

Class 1 is ceramics. This is when we talk about the NP0 or CGO ceramics. As you can see in the chart above, we have the NP0 types. The temperature coefficient of NP0 is zero, meaning there is no capacitance drift over the whole temperature range.

This is the best ceramic power out there and most stable ceramics you can find for Class 1.

Class 1 is based on Titanium Oxide. For a low relative permittivity, it means for NP0 and COG, there is a very limited range of capacitance values. For NP0 types, capacitance values available in the market are just a few picofarads, or a few nanofarads.

You won't find any large nanofarads, or even microfarads, with an NP0. To have an absolutely linear temperature performance means there is no deviation over the whole temperature range and minimum aging behavior.

Class 1 Ceramics (e.g.: NP0 = C0G)

• Based on titanium oxide

• Low relative permittivity εr >> only smaller capacitance values possible

• Linear temperature performance

• Minimum aging behavior

• Low (down to zero) voltage dependency

In comparison, we have Class 2 ceramics, where we normally have the X5R, X7R, X7S, or X7T for various applications.

The most used parts of Class 2 ceramics is X7R and X5R, where it can reach much higher capacitance values because of the higher permittivity of this ceramic powder.

Class 2 Ceramics (e.g.: X7R, X5R, Y5V)

• Based on barium titanate

• Higher relative permittivity εr >> higher capacitance values possible

• Not linear (and stronger distinct) temperature dependency

• Notable aging behavior

• High voltage dependency

• Piezoelectric effects can result in microphonic noise

One cannot assume the ceramic powder of different MLCC manufacturers will be the same. The ceramic category name will not define the powder composition, only the accordance to the max. technical limits will be specified.

Take into account there are often standard and low-profile series with the same ceramic powder and technical features, but different electrical and mechanical performance. The DC Bias performance might be different between competitor parts.

Temperature Dependency

In the above chart, the redline is the NP0, which is absolutely stable over the whole temperature range.

There can be a high voltage tendency, meaning the DC biased behavior you see with an X7R or a X5R is worse than on the Y5V. You will see the real capacitance value you can use is less than 50%.

When you have different vendors, it is important you have the same values on the datasheet. Not each X7R will be the same with each and every competitor on the market. This is because you’re able to add some additives into the ceramic powder, giving you behavior in the ceramic capacitor.

Study the datasheets to see the performance over the voltage or temperature range of each capacitor.

Mid & High Voltage Series

• Capacitance range: 10pF to 470nF

• Rated voltage DC: 200V / 250V / 500V / 630V / 1000V / 2000V / 3000V

• Temperature: Max:125°C / Min: -55°C

• Ceramic: NP0 / X7R

• Size: 0603 / 0805 / 1206 / 1812

MLCCs are good for DC voltages from 200V up to 3kV.

For MLCC capacitors, you will not see large-scale microfarad capacitors. The temperature range is in the range of NP0 and X7R, meaning it’s from -55°C to 125°C. Sizes vary from 0603 to 1812.

Applications:

• DC/DC converters

• To meet surge & burst requirements on I/O ports

• DC blocking / HV coupling

• Snubber for high frequency converters

High Voltage MLCCs in Comparison to Safety MLCCs Recap Continues

Check back in for more information as we continue to recap our High Voltage MLCCs in Comparison to Safety MLCCs webinar.

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