That's debatable .
Ceramic caps of this size are often used in fixed frequency SMPS, but with high harmonic content so neither test method is purely accurate. But CC sine @f is the standard used by testers and MFG's.
Also dielectric layers with many non -homogeneous and variable diameter ratios of laminations with metallic interface affects ESR, Rp and C simultaneously with different test conditions.
Thus C and ESR both change.
Hi again Tony,
Well if the ESR is going to change much then we have to know what is causing that and then test accordingly. The power supply caps are easier to test i guess because they either have low ESR or the ESR is much higher than expected. For a little historical data, my devices never actually failed before the cap ESR changed pretty drastically, which is easy to detect with either method. If we want more explicit data on a cap then we really have to be willing to test more carefully. That's only if that kind of exacting data is really needed at the time, such as when specifying the capacitor for the first time.
When we do a simple test on a resistor, we can apply a DC voltage and measure the current. We then calculate R=E/I and we're done. If we have to test a potentiometer we might still apply a DC voltage, but then we'd have to plot the curve of the current in order to calculate the curve of the resistance.
So if the ESR changes much then we have to know what makes it change and then test accordingly. If it changes with voltage, then we have to test with different bias voltages, if it changes with frequency, then we have to test with different frequencies. If if changes with both, then we have to test with different bias voltages and different frequencies, then we'd have to use a 3d plot to plot the variations due to both parameters. If we also wanted to plot with temperature (a good thing too) then we'd want to do the test with bias voltage and frequency over several different temperatures, so we'd get several different 3d plots.
The main idea here is that if we want to go beyond the basic test for ESR, then we have to be willing to go the distance just like with any other test.
So i do agree that if the ESR changes (second sentence, first paragraph of previous post) then we have to take steps to test more rigorously.
Very good point BTW, especially if we start to take temperature effects into account. Temperature is such a pain sometimes and everything heats up at one time or another