What devices are used? What are the pitfalls, you can trap in using the equipment?

1. KEMET Webinar - Measuring capacitors
properties correct

2. Measure ESR ????

5. Agenda
• Standards for measuring capacitors
• Equipment DMM, RLC-Bridge and VNA
• Measurement principles
• Taken cares of …

6. What we measure
We don’t measure
• Impedance
• Capacitance
• Inductance
• Resistance
You can only measure
• Voltage
• Current
• Phase between V and I

7. Measurement principle
Not discussed here

8. EIA-198-D
• Testsetup and conditions for :
• Ceramic dielectric capacitors classes I, II, III
• Polymer and Tantal measured the same way
• Room temperature 23,5°C, normal air pressure 1023mb
C_min C_max Test
Frequency
V_rms V_DC
0,1pF 1nF 1kHz 1V 0V
1nF 10µF 1kHz 1V 0V
10µF 1800µF 120Hz 0,5V 0V

9. Measurement principle II
Series
Parallel

10. When measure serial or parallel Impedance
Parallel
Medium Z
Series

11. WHAT ABOUT CONSTANT
CURRENT ?

12. C = ic * dv/dt
• Charge with a constant current
• Dielectric dependant charge curves look differrent
• dv1/dt1 ≠ dv2/dt2
dv1
dv2
dt1 dt2

13. RC-Ladder

14. RLC BRIDGE

15. Impedance

16. Principle of C measurement
• We only measure voltage, current and phase/time
• Impedance is a frequency dependant resistor
• Signal generator has a source impedance ZS
• Voltage split up between to Impedance

17. EIA-198-D
• Testsetup and conditions for :
• Ceramic dielectric capacitors classes I, II, III
• Polymer and Tantal measured the same way
C_min C_max Test
Frequency
Vrms V_DC
0,1pF 1nF 1kHz 1V 0V
1nF 10µF 1kHz 1V 0V
10µF 1800µF 120Hz 0,5V 0V

18. Measure at 0V DC-Bias
• Applies Only to Class II and III (X7R, X5R, X8R | Z5U, Y5V)
26

19. incorrect C measurement wrong VAC
27

20. Capshift caused by AC voltage
28
we need
1Vrms
Here

21. Correct Measurement with 1VAC
29

22. capacitance change with AC voltage
30

23. VNA

24. VNA Omicron 100 Lab

25. https://www.omicron-lab.com/

26. VNA
• VNA = Vector network analyzer
• Magnitide and Phase

27. Measurement techniques
• Capacitance ↑ or frequency ↑ → Xc ↓ << 50Ω
• 2-Port measurement
• Capacitance ↓ or frequency ↓ → Xc ↑ >> 50Ω
• 1-Port measurement

28. SECTION

29. Two-Port Header
38

30. SECTION
OnePort measurement
Two Port measurement
Two Port calibration

31. One port measurement
• Calibration area
OnePort measurement

32. Upright

33. Bode 100 Software

34. Capacitance and ESR

35. Wrap up
• Principles of capacitance measurement
• Load /Charge curve
• Voltage, Current & Phase
• Low - Z use series Circuits/ -model above 100kHz
• High - Z use parallel Circuits/ -model below 1kHz

36. Thank You!
Axel Schmidt
Senior Field Application Engineer
Cell +49 172 89 25 284
email: AxelSchmidt@kemet.com
Hermann-Köhl-Str. 2
86899 Landsberg am Lech
Germany
www.kemet.com