Do multi-layer ceramic capacitor specifications vary within a dielectric class?

Question

According to the linked pages below: Class 2 MLCCs are most commonly made of alkaline earth titanates, specifically barium titanate, along with suitable additives such as aluminum silicate, magnesium silicate, and aluminum oxide.

Do differences in the specific dielectric material or additive affect the specifications of a class 2 MLCC? In other words, can I expect every 0805 50V X7R to behave the same?

Comparing two 1206 X5R 10% 25V capacitors (datasheet links below), there are clear differences in the DC bias characteristics. Can parts be expected to vary more than this?

https://psearch.en.murata.com/capacitor/product/GJ831CR61E106KE83%23.pdf

http://www.samsungsem.com/kr/front/downloadcms.do?path=/kr/support/product-search/mlcc/__icsFiles/afieldfile/2016/01/21&fileName=Data%20sheet_CL31A106KAHNNNE.pdf

Thanks

https://en.wikipedia.org/wiki/Ceramic_capacitor#Class_2_ceramic_capacitors https://passive-components.eu/class-ii-ceramic-dielectrics-types-performance-and-applications/

Answer 1

The class of a ceramic dielectric tells you a lot less than you think, it only described the temperature coefficient.

Unfortunately, the voltage coefficient is a lot more important these days, with very exotic high K ceramics.

Manufacturers do use different ceramics with different voltage coefficients for different package sizes even within the same range of capacitors. The reason for this is that as the package shrinks, they tend to increase the ceramic K to allow high values of C to be realised, usually at the expense of voltage coefficient.

If the actual value of minimum capacitance is important, say for stabilising an LDO, then it's imperative to get the longform datasheet from the manufacturer, and stick to a specific value, voltage rating and package size. The shortform data sheet does not usually have the required information.

Answer 2

No, you cannot. Voltage coefficient and actual temperature coefficient will vary, thought the latter should fit within the specified range of +/-15% over the military range.

You should read the datasheet (probably the required information has to be extracted online these days) and specify and particular manufacturer and part number if those characteristics are important.

Answer 3

X7R and X5R dielectrics "saturate"

Even if they are the exact same composition and batch, the degree of saturation depends on the ratio of thickness to voltage in that particular capacitor design.

Imagine different chokes. Exactly the same iron is used, but saturation current depends on core size and number of turns.