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Vishay's Capacitors Frequently Asked Questions
 

Aluminum Capacitors

  1. What is the standard ppm level set by Vishay for its aluminum capacitors?
  2. Is Vishay's 235 EDLC-HVR the only supercapacitor series with AEC-Q200 qualification?
  3. Under what capacitor technology is the EDLC categorized? Why is it AEC-Q200 qualified?
  4. I want to use the 235 EDLC-HVR in my application as a power back-up source operating at 4 V. What capacitance value is required to supply 1.5 A for 8 s until the operating voltage drops from 4 V to 2 V?
  5. What is the maximum lifetime Vishay can guarantee for the 235 EDLC-HVR series operating at 55 °C and 1.6 V?
  6. What are the surge voltage and peak current specifications for 235 EDLC-HVR?
  7. What is the failure mode of the 235 EDLC-HVR?
  8. Why does the 235 EDLC-HVR need cell balancing when it's used in serial connections?
  9. Why are there limitations in high / low air pressure for EDLC devices (high air pressure: 150K Pa; low air pressure: 8.5K Pa)?
  10. How long is the lifetime for the sealing rubber material used in EDLC devices?
  11. Are there differences in the characteristics for standard and ruggedized EDLC versions in the low temperature range?
  12. How is lifetime expectancy for EDLC capacitors calculated with respect to operating voltage and temperature? (Useful life at 2000 h at 85 °C , 2.6 V)
  13. What is the difference between the 196 HVC and 235 EDLC?
  14. Can the lifetime expectancy of Vishay's 235 EDLC-HVR exceed 16 years?
  15. What are the factors to be considered when calculating the lifetime expectancy of the 235 EDLC-HVR?
  16. Can an uncharged (0 V) EDLC capacitor pass a 95 °C storage test?

MLCCs

  1. What is the standard ppm set by Vishay for its MLCC?
  2. What is the frequency characteristic on impedance for Vishay's RF MLCC?
  3. What is MSL? What is MSL level of Vishay's RF MLCC?
  4. Why is VJ...32 series intended for special applications and not automotive?
  5. Does Vishay's RF MLCC have superior ESR performance?
  6. Does Vishay's RF MLCC have superior SRF performance?
  7. How do you choose a High Q MLCC?

Ceramic Capacitors

  1. What are the primary differences between AY1 and AY2 capacitors? Are they interchangeable?
  2. When to select SMDY1 over leaded type Y1?
  3. How wide of a temperature range does the X0U characteristic in the K..H series have?
  4. What is the difference between an X / Y class safety capacitor and a non-safety capacitor?
  5. What is the maximum operating temperature for Vishay safety capacitors?
  6. When should leaded MLCC product be used?
  7. When should customers consider a SMD Y1 device?
  8. The AY1 series can pass 10 kVAC impulse testing. What is the test condition?
  9. For the AY1 ceramic capacitor series, what is the meaning of the Y5U dielectric type?
  10. Under what conditions should ceramic capacitors be stored?
  11. My application has constraints with PCB and I require high temperature MLCC. What can Vishay offer?
  12. What are advantages of Vishay leaded MLCCs in automotive applications?
  13. Why do OBCs require both AY1 and AY2 capacitors?
  14. What is the main advantage of VY1*C series compared to standard VY1*Q series?

Film Capacitors

  1. Why do customers prefer to use film capacitors to replace aluminum capacitors in OBCs?
  2. What are X, Y capacitors and what is the difference between Y1 and Y2 ratings?
  3. Is there development plan of F340 X1 to operate at 125 °C?
  4. Which applications to select between X1 and X2 capacitors?
  5. Is F340 X1 produced in multiple location?

Wet Tantalum Capacitors

  1. What is the difference between 134D and T34 capacitors since both are being used primarily for oil and gas applications?
  2. Is the T24 recommended for avionics applications, particularly in radar systems that may be exposed to high temperatures?
  3. Why are the T24 and T22 only available in one case size?
  4. What is the difference between wet and aluminum capacitors?
  5. Do Vishay wet tantalum capacitors need voltage derating up to +85 °C?
  6. Can Vishay wet tantalum capacitors be used in high altitude applications?
  7. Is there defined shelf life for solid and wet tantalum (Ta) capacitors, surface-mount or through-hole?
  8. What is the main advantage of SMD Wet Tantalum T24 series against the standard leaded products?

Aluminum Capacitors

Q1.

What is the standard ppm level set by Vishay for its aluminum capacitors?

A1.

For non-automotive customers, the maximum is 0.3 ppm. For automotive customers, the maximum is 0.03 ppm, or one failure unit maximum.

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Q2.

Is Vishay's 235 EDLC-HVR the only supercapacitor series with AEC-Q200 qualification?

A2.

All our EDLC series are AEC-Q200 qualified according to the respective test plans (220 EDLC, 225 EDLC-R, 230 EDLC-HV, and 235 EDLC-HVR). In addition, all EDLC series are UL-recognized.

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Q3.

Under what capacitor technology is the EDLC categorized? Why is it AEC-Q200 qualified?

A3.

The EDLC falls under the aluminum capacitor categorization. It is AEC-Q200 qualified to support automotive applications, primarily for back-up energy storage.

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Q4.

I want to use the 235 EDLC-HVR in my application as a power back-up source operating at 4 V. What capacitance value is required to supply 1.5 A for 8 s until the operating voltage drops from 4 V to 2 V?

A4.

Required energy Q = 4 V x 1.5 A x 8 s = 48 Ws, Q = ½ x C x (Vmax2 - Vmin2), Vmax = 4 V and Vmin = 2 V. Required C = 2 x Q /(Vmax2 - Vmin2) = 2 x 48 / (42 - 22) = 2 x 48 / (12) = 96 / 12 = 8. C = 8 F. As the voltage rating of a single capacitor is 3 V, two capacitors with a capacitance of > 16 F must be connected in series. So, from the 235 EDLC-HVR series, two 20 F / 3.0 V capacitors will meet this requirement.

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Q5.

What is the maximum lifetime Vishay can guarantee for 235 EDLC-HVR series operating at 65 °C and 1.6 V?

A5.

Below 2.2 V, the calculation for doubling the lifetime is no longer valid. The useful lifetime t = t0 x 2((T0-T)/ΔT0) x 2((U0-U)/ΔU0) = 2000 x 2((65-55)/10) x 2((3.0-2.2)/0.2) = 64 000 hours.

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Q6.

What are the surge voltage and peak current specifications for 235 EDLC-HVR?

A6.

The maximum surge voltage is 3.15 V. The maximum peak current at 65 °C is 35 A and at 85 °C it's 30 A. More parameters could be found under this series on www.vishay.com.

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Q7.

What is the failure mode of the 235 EDLC-HVR?

A7.

The failure mode for a supercapacitor is usually an "open circuit" / "high ohmic resistor." Until that happens, ESR rises indefinitely and the capacitance will decline.

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Q8.

Why does the 235 EDLC-HVR need cell balancing when it's used in serial connections?

A8.

Series-connected supercapacitors may run into voltage imbalance issues, which could cause an overvoltage of a single cell. To prevent this, resistors can be used for balancing.

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Q9.

Why are there limitations in high / low air pressure for EDLC devices (high air pressure: 150K Pa; low air pressure: 8.5K Pa)?

A9.

High and low air pressure limitations are the consequence of the applied elastic sealing of the capacitor's case. Violating the limits can cause short circuits due to mechanical deformations.

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Q10.

How long is the lifetime for the sealing rubber material used in EDLC devices?

A10.

It's similar to aluminum capacitor itself, more than 10 years.

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Q11.

Are there differences in the characteristics for standard and ruggedized EDLC versions in the low temperature range?

A11.

No. They have the same electrical specifications, even in the low temperature range. However, they do have performance differences in high stress environments, e.g. at higher relative humidity.

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Q12.

How is lifetime expectancy for EDLC capacitors calculated with respect to operating voltage and temperature? (Useful life at 2000 h at 85 °C and 2.6 V)

A12.

There are two major stress factors that determine the operational life of an EDLC capacitor:

  • Temperature: a 10 °C decrease in operating temperature results in double the lifetime expectancy
  • Operating voltage: a 0.2 V decrease in operating voltage results in double the lifetime expectancy

Estimates for specified performance targets for Vishay's 235 EDLC-HVR series are indicated in the table below (extrapolated from the maximum stress point).

  85 °C 75 °C 65 °C 55 °C 45 °C
3.0 V     2000 h 4000 h 8000 h
2.8 V   2000 h 4000 h 8000 h 16 000 h
2.6 V 2000 h 4000 h 8000 h 16 000 h 32 000 h
2.4 V 4000 h 8000 h 16 000 h 32 000 h 64 000 h
2.2 V 8000 h 16 000 h 32 000 h 64 000 h 128 000 h

Green: safe operating area

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Q13.

What is the difference between the 196 HVC and 235 EDLC?

A13.

Please see the benchmark table below.

  SUPERCAPACITORS
220 / 225 / 230 / 235 EDLC
HYBRID CAPACITOR
196 HVC
TRADITIONAL
NiMH / Li-ion Cells
Power density 2.000 W/kg to 10.000 W/kg 2.000 W/kg to 5.000 W/kg 500 W/kg to 1.500 W/kg
Energy density 3 Wh/kg to 5 Wh/kg 20 Wh/kg to 200 Wh/kg 80 Wh/kg to 200 Wh/kg
Lifetime expectation > 15 years 10 years to 15 years 3 years to 8 years
Cycle count > 1.000.000 (100% DOD) > 100.000 (100% DOD) < 2.000 (80% DOD)
Self discharge after 20 days 0% < 5 % / month < 5 % / month
Temperature range -40 °C to +85 °C -20 °C to +85 °C -20 °C to +55 °C
Ultra fast charge capability yes yes yes

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Q14.

Can the lifetime expectancy of Vishay's 235 EDLC-HVR exceed 16 years?

A14.

At 35 °C and a voltage of 2.2 V, the lifetime expectancy for the 235 EDLC is approximately 256 000 hours, or ∼29 years!

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Q15.

What are the factors to be considered when calculating the lifetime expectancy of the 235 EDLC-HVR?

A15.

The useful life of an EDLC capacitor depends on ambient temperature and working voltage. Every 10 K lower temperature will double the lifetime; similarly, every 200 mV lower working voltage will also have same effect.

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Q16.

Can an uncharged (0 V) EDLC capacitor pass a 95 °C storage test?

A16.

The maximum specified temperature for Vishay's EDLC is 85 °C.

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MLCCs

Q17.

What is the standard ppm set by Vishay for its MLCC?

A17.

MLCC parts are below 0.04 ppm.

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Q18.

What is the frequency characteristic on impedance for Vishay's RF MLCC?

A18.

The magnitude of the impedance |Z| for a capacitor, and equivalent series resistance (ESR), varies with frequency. This phenomenon is called the "frequency characteristic." The frequency characteristics of capacitor differ greatly under different technology. Vishay's RF MLCC adopts a Noble Metal Electrode system under wet build process, has low impedance, and exhibits excellent frequency characteristics. Below, ESR comparison data shows Vishay's ESR is lower than its competitors.

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Q19.

What is MSL? What is the MSL level of Vishay's RF MLCC?

A19.

MSL is the abbreviation for Moisture Sensitivity Level. It applies to the phenomenon in which a cubical expansion is generated by the gasification of moisture in the MLCC, which is then absorbed by the product through the reflow soldering process. The result is component failure. The MSL expresses the risk of failure. As MSL increases, the risk becomes higher. Therefore, it is necessary to prevent moisture absorption when the level reaches 2 or higher. For Vishay's RF MLCC (and all Vishay surface-mount MLCCs), the MSL = 1.

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Q20.

Why is VJ....32 series intended for special applications and not automotive?

A20.

The VJ....32 series offers two important characteristics. First, it has a lead (Pb)-bearing termination finish. This is key in preventing the formation of tin whiskers, which is a reliability issue, especially in applications such as Low Earth Orbit (LEO) satellites. Second, the part is qualified to AEC-Q200 requirements. This means it is a reliable device and can be used in less demanding high reliability applications, such as LEO satellites. Since it does have a lead (Pb)-bearing termination finish, it is not recommended for pure automotive applications, as many of these require lead (Pb)-free products.

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Q21.

Does Vishay's RF MLCC have superior ESR performance?

A21.

At higher frequencies (above 600 MHz), Vishay's Ag / Pd MLCCs have lower ESR than nickel and copper (BME) devices. Lower ESR translates into lower temperature rise and low losses, thus better and optimum performances.

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Q22.

Does Vishay's RF MLCC have superior SRF performance?

A22.

Vishay's RF MLCC offers better SRF performance than the competition, especially for capacitance values ≤ 1 pF. Vishay's 250 V / 0.3 pF device in the 0805 case size can operate under higher frequencies up to 14 GHz.

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Q23.

How do you choose a High Q MLCC?

A23.

Q = 1/(2π • ESR • f • C)

where f = frequency (Hz), C = capacitance (F), and ESR is equivalent series resistance (Ω)

A lower ESR will result in a higher Q, as will a lower frequency and lower capacitance. So, if at 50 Hz we choose a 0.01 µF, 2 GHz ∼ 3.5 GHz device, a narrow capacitance (< 100 pF) and tight tolerance (± 0.1 p, ± 0.05 p) is necessary.

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Ceramic Capacitors

Q24.

What are the primary differences between AY1 and AY2 capacitors? Are they interchangeable?

A24.

The AY1 is an X1 / Y1 class device with double or reinforced insulation. The AY2 is an X1 / Y2 class device with basic or supplementary insulation. Both are AEC-Q200 qualified.

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Q25.

When to select SMDY1 over leaded type Y1?

A25.

SMDY1 series allows for reflow soldering. It can replace through-hole type devices without clearance issues on the back of PCB.

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Q26.

How wide of a temperature range does the X0U characteristic in the K..H series have?

A26.

The X0U characteristic has a +22 % / -56 % capacitance change within the range of -55 °C to +175 °C. While this seems like a very loose capacitance over a wide temperature range, from -55 °C to +125 °C the X0U fulfills the same ± 15 % capacitance range as the X7R.

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Q27.

What is the difference between an X / Y class safety capacitor and a non-safety capacitor?

A27.

Safety capacitors for EMI / RFI interference suppression must have safety certification (including VDE / UL / CQC) according to the IEC standard. Non-safety capacitors don't require this certification. X capacitors are used across the power lines, and the failure of an X capacitor would not lead to an electric shock, but it could open safety fuses or circuit breakers, and in an extreme case, catch on fire. Y capacitors on the other hand are connected between a live conductor and the metal shielding, which someone could potentially touch. As Y capacitors are always grounded, they act as grounding capacitor to prevent electrical shock.

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Q28.

What is the maximum operating temperature for Vishay safety capacitors?

A28.

It depends on the product family. For our AY and VY series ceramic capacitors, it's 125 °C max. For our X1, X2, and Y2 film capacitors there is a 105 °C, 110 °C, and 125 °C max, respectively. For details, please check the series datasheet or contact the Vishay Business Marketing department.

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Q29.

When should leaded MLCC product be used?

A29.

If there is no PCB, example in motor control applications, customer often uses a leaded MLCC. In other applications, where they need to avoid the bedding effect or require better heat dissipation, they also prefer to use a leaded version. Leaded MLCC withstand higher vibration as compared to standard SMD type.

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Q30.

When should customers consider a SMD Y1 device?

A30.

When customers need a low profile due to height limitations and/or reflow soldering; PCB real estate limitation also encourages the use of SMD. Vishay's SMDY1 offers 4 mm max. body thickness, which is much lower than leaded devices.

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Q31.

The AY1 series can pass 10 kVAC impulse testing. What is the test condition?

A31.

In impulse voltage testing, each individual capacitor receives 10 kVAC impulses for each polarity, in accordance with the IEC standard.

In the impulse voltage waveform below, the time T1 is the rise time for the pulse to go from 0 % to 100 % of the peak voltage. T2 is the time it takes for the voltage to go from 0 % to 100 % of the peak and then back to 50 %.

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Q32.

For the AY1 ceramic capacitor series, what is the meaning of the Y5U dielectric type?

A32.

Y5U is dielectric material that defines temperature characteristic of capacitance for Class 2 ceramic capacitors.

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Q33.

Under what conditions should ceramic capacitors be stored?

A33.

The capacitors must not be stored in a corrosive atmosphere, where sulfide or chloride gas, acid, alkali, or salt are present. Exposure of the components to moisture should be avoided. The solderability of the leads is not affected by storage of up to 24 months (at temperatures from +10 °C to +40 °C and up to 60 % RH).

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Q34.

My application has constraints with PCB and I require high temperature MLCC. What can Vishay offer?

A34.

In space-crunched applications where there is no space for PCB or direct mounting of the component, through-hole capacitors are preferred. However, in applications that encounter higher temperatures in the range of 200 °C (like exhaust sensors and engine control), leaded ceramics provide advantages.

Vishay's HOTcap (K....H series) devices aren't ordinary devices; they're built for the most extreme automotive operating conditions, especially high temperature.

SMD Leaded MLCC
  • PCB bending and vibration may cause mechanical stress and capacitor cracks
  • More robust to thermo-mechanical stress and vibration
  • Impact on the MLCC is reduced as the lead wires absorb the bending stress
  • The capacitor can be welded or soldered directly to a lead frame and overmolded with plastic

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Q35.

What are advantages of Vishay leaded MLCCs in automotive applications?

A35.

Vishay's leaded MLCC handles temperature up to 200 °C. This also avoids any possible crack problem under harsh conditions. Vishay's leaded MLCC uses own in-house MLCC chip which is fully AEC-Q200 qualified.

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Q36.

Why do OBCs require both AY1 and AY2 capacitors?

A36.

They are used to protect against surge and impulse voltages and provide double insolation. They are connected to ground to protect users and surrounding components. Vishay's ceramic Y capacitors are AEC-Q200 qualified and are able to withstand high pulse rates.

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Q37.

What is the main advantage of VY1*C series compared to standard VY1*Q series?

A37.

VY1*C series can support pulse load up to 10 kVAC against the standard requirement of 8 kVAC and come with 85 /85 / 1000 h RH with applied rated voltages. VY1*C is compact in size and popularly used in many segments including industrial, consumer and servers' applications.

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Film Capacitors

Q38.

Why do customers prefer to use film capacitors to replace aluminum capacitors in OBCs?

A38.

OBCs require high rated voltage > 500 VDC at 85 °C and very high ripple current from DC-Link capacitors. Film capacitors can support much higher rated voltage and ripple current than aluminum devices. For example, Vishay's MKP1848 series can support 1200 VDC at 85 °C, with ripple current of 40.5 A IRMS. Therefore, customers can reduce quanityt of capacitors used if they choose film capacitors for DC-DC applications. In addition, lifetime of film capacitor is > 10 years and do not encounter dry out problem as seen in aluminium electrolytic capacitors.

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Q39.

What are X, Y capacitors and what is the difference between Y1 and Y2 ratings?

A39.

X, Y capacitors are different types of safety capacitors that are required for RFI suppression. All safety capacitors must be certified according to IEC 60384-14. X capacitors are used across the power lines, while Y capacitors are used between power lines and the earth. Both Y1 and Y2 are subclasses of Y capacitors with different rated voltage (Y1 ≤ 500 VAC, Y2 ≤ 300 VAC) and peak impulse voltage (Y1: 8.0 kV, Y2: 5.0 kV). In addition, Y1 is targeted at high pulse applications, while Y2 is intended for general purpose applications.

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Q40.

Is there development plan of F340 X1 to operate at 125 °C?

A40.

Options will be considered as we have the capability to build to automotive specifications depending on market demand.

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Q41.

Which applications to select between X1 and X2 capacitors?

A41.

Vishay's F340 X1 safety capacitors offer rated voltage at 480 VAC; it is recommended for Industrial 3-phase application. Whilst Vishay's X2 capacitors MKP339 X2 series offer rated voltage at 310 VAC, it is recommended for commercial single phase and lower VRMS applications.

Category Peak Impulse
X1 4.0 kV
X2 2.5 kV
Y1 8.0 kV
Y2 5.0 kV

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Q42.

Is F340 X1 produced in multiple location?

A42.

Yes, it is based on pitch size. 27.5 mm pitch products are produced in India; 37.5 mm and 52.5 mm pitch products are produced in Portugal. However, we have options for risk mitigation production if situation requires Vishay to react in any of the production location mentioned above.

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Wet Tantalum Capacitors

Q43.

What is the difference between 134D and T34 capacitors since both are being used primarily for oil and gas applications?

A43.

The 134D is qualified to 100 g shock and 20 g vibration, but not random. The T34 series is qualified to 500 g shock, 80 g vibration, and 54 g random. The device also offers an improve life-test from 500 hours to 1000+ hours.

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Q44.

Is the T24 recommended for avionics applications, particularly in radar systems that may be exposed to high temperatures?

A44.

The T24 is a high temperature version of the T22 series. Both series are hermetically sealed wet tantalum capacitors for surface mounting and are capable of withstanding 300 cycles of thermal shock. They are also both available in RoHS-compliant versions with 100 % Sn and SnPb finishes and can survive 500 g shock, 80 g vibration, and 27.78 g random vibration. The T24 series extends the temperature performance of the T22 series to 200 °C with voltage derating. We currently have two ratings available and will have others later in the year.

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Q45.

Why are the T24 and T22 only available in one case size?

A45.

Vishay developed the T22 and T24 SMD devices targeting the axial T1 case size. SMD parts are better for mounting on the PCB compared to the T1 axial case and also helps in PCB space saving.

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Q46.

What is the difference between wet and aluminum capacitors?

A46.

The difference is mainly in reliability and lifetime. Wet capacitors have very high reliability and no limit on lifetime, while the lifetime of aluminum devices — which are very sensitive to high temperatures — is based on the specifications of each series. For example, the lifetime of our 150 RMI series aluminum capacitors is 4000 hours to 10 000 hours at 105 °C. Aluminum capacitors also have tendency to drop in capacitance, since the electrolyte inside the can could either dry-out or leak.

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Q47.

Do Vishay wet tantalum capacitors need voltage derating up to +85 °C?

A47.

They do not require derating up to +85 °C. This enables designers to achieve more capacitance per specified rated voltage when used below +85 °C.

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Q48.

Can Vishay wet tantalum capacitors be used in high altitude applications?

A48.

Vishay wet tantalum capacitors have been tested to MIL-STD-202, method 105C, test condition D, for 100 000 feet (equivalent to 30,480 meters).

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Q49.

Is there defined shelf life for solid and wet tantalum (Ta) capacitors, surface-mount or through-hole?

A49.

The dielectric Ta2O5 is a very stable compound and therefore not subjected to shelf-life limitations, if stored under recommended storage conditions. Typically, tantalum capacitors have no breakdown mechanism in their electrical properties.

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Q50.

What is the main advantage of SMD Wet Tantalum T24 series against the standard leaded products?

A50.

The main advantage of T24 is high volumetric efficiency under small package. This SMD wet tantalum also derives extremely high CV, enhanced reliability in hermetically sealed package and built with increased thermal shock cycles for harsh and high temperature applications.

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