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Special technical subjects
WIMA box encapsulation
Both, SMD and through-hole WIMA DC capacitors are produced with the proven box technology, showing the following substantial advantages in comparison with non-encapsulated, moulded or dipped capacitor versions:
- Safe protection of the capacitor element against the mechanical stresses which occur during processing and operation.
- No danger of delamination, internal cracks or tearing away of the contacts due to similar expansion coefficient and the elasticity of the construction.
- Excellent self-healing properties of metallized WIMA capacitors due to pressure free layers in the winding element.
- Flame retardant plastic case in accordance with UL 94 V-0.
- Clearly defined dimensions allows for close placement and exact setting of parts on PC-boards. Even larger parts are easily robotically insertable.
- Easy second source because of standardized box size.
WIMA self-healing behaviour as a quality standard
The capacitors manufactured by WIMA in winding technology are produced as single winding capacitors. The most effective pressure on the layers necessary for good self-healing behaviour can be individually adjusted for each capacitor.
WIMA capacitors are known for their excellent self-healing behaviour. A DC voltage test is used to demonstrate the self-healing properties:
This clearly shows that stacked MKT film capacitors short-circuit after a few self-healing processes. Also, the rate of the breakdown voltage is usually distinctly lower. A low loading capacity and a reduced life time are the result. WIMA capacitors, on the other hand, are surprisingly hardy. As well as having very high breakdown voltage, they self-heal much more frequently than corresponding stacked film capacitors. The test clearly proves the high reliability and long life-span of WIMA MKS capacitors, well above the data given in the catalogue.
- the capacitor to be tested is connected over a series resistance of R ~ 10 k at with adjustable direct voltage source.
- the voltage on the capacitor is observed with a line recorder or an oscilloscope (see diagram).
- the voltage applied to the capacitor is continually increased, over and above the rated voltage for the capacitor, up to the first self-healing process. The line recorder shows clear breakdowns in the capacitor voltage and then recharging until the next self-healing occurs.
This clearly shows that stacked MKT film capacitors short-circuit after a few self-healing processes. Also, the rate of the breakdown voltage is usually distinctly lower. A low loading capacity and a reduced life time are the result. WIMA capacitors, on the other hand, are surprisingly hardy. As well as having very high breakdown voltage, they self-heal much more frequently than corresponding stacked film capacitors. The test clearly proves the high reliability and long life-span of WIMA MKS capacitors, well above the data given in the catalogue.
Selection of capacitors for pulse applications
The maximum permissible AC voltage that can be applied to capacitors in sinusoidal waveform applications, can be determined from the graphs in the respective capacitor ranges.
However, where pulse conditions exists, the following procedure is to be observed to ensure that the correct capacitor rating is selected for a particular duty:
Rated voltage Ur: The rated voltage of a capacitor against a zero potential reference point shall take into consideration that the dielectric strenght of the capacitor film diminishes with rising frequency. The calculation of the required rated voltage of a capacitor must therefore allow for the correction factor k; where k = dielectric strength of the film at the frequency f in % is shown in graph 1.
Graph 1: Dielectric strength of Polypropylene film as a factor of frequency (general guide).
The calculation of the required dielectric strength is shown in the following example(Umin, Umax have the same polarity).
Furthermore the rms voltage derived from the peak to peak voltage shall not be greater than the nominal AC voltage rating of the capacitor to avoid the ionization inception level:
Urms < UACrated
Maximum current: The voltage gradient or rise time of the pulse is taken as the reference point when calculating the maximum current rating of the end contacts. The maximum possible current load on the end contacts is calculated by means of the voltage rise of the pulse (pulse rise time F).
Imax = F x C x 1.6
The data of the rated pulse rise time Fr for pulses equal to the rated rated voltage figure in the technical data of the different types. With low voltage rise in operation (UPP) the permissible current load is calculated as follows:
for example Ur = 63 V, UPP = 12 V, Fr = 50 V/µsec.
hence Fmax
When using maximum current ratings, self-heating must be taken into account at higher frequencies, and must not exceed 8 K.
Dissipation (heat losses): The heat dissipated by a capacitor when stressed by non-sinusoidal voltages or when under pulse conditions can be approximately determined from the following formula:
pulse frequency =
temperature rise in K =
Table 1: The data is for ordinary assembly and ventilation conditions avoiding radiant heat within the chassis of the equipment.
In applications where reliability is critical, it is recommended to measure the surface temperature of the capacitor and to take into account that the temperature within that capacitor will be approximately 5 K above the case temperature.
Determining the permissible AC voltage and AC current at given frequencies.
To determine the permissible AC voltage (sinusoidal) for applications in a higher frequency spectrum, graphs showing AC voltage derating with frequency are available for the respective WIMA series. The diagrams refer to a permissible self-heating of:
Δϑ < 10 K.
For the WIMA MKP 10 / 0.01µF / 630VDC/400VAC, for example, this shows - when f = 50kHz - a permissible AC voltage of
Urms = 280 V (graph 2).
Graph 2: Permissible AC voltage in relation to frequency at 10°C internal temperature rise (general guide).
The AC voltage given in the diagrams can also be used to determine the maximum effective current
The calculated maximum value of the effective current
must not exceed the maximum current rating specified in the maximum pulse rise time calculation (see Fmax above). In this case, the operating AC voltage is to be reduced accordingly.
However, where pulse conditions exists, the following procedure is to be observed to ensure that the correct capacitor rating is selected for a particular duty:
Rated voltage Ur: The rated voltage of a capacitor against a zero potential reference point shall take into consideration that the dielectric strenght of the capacitor film diminishes with rising frequency. The calculation of the required rated voltage of a capacitor must therefore allow for the correction factor k; where k = dielectric strength of the film at the frequency f in % is shown in graph 1.
Graph 1: Dielectric strength of Polypropylene film as a factor of frequency (general guide).
The calculation of the required dielectric strength is shown in the following example(Umin, Umax have the same polarity).
Furthermore the rms voltage derived from the peak to peak voltage shall not be greater than the nominal AC voltage rating of the capacitor to avoid the ionization inception level:
Urms < UACrated
Maximum current: The voltage gradient or rise time of the pulse is taken as the reference point when calculating the maximum current rating of the end contacts. The maximum possible current load on the end contacts is calculated by means of the voltage rise of the pulse (pulse rise time F).
Imax = F x C x 1.6
The data of the rated pulse rise time Fr for pulses equal to the rated rated voltage figure in the technical data of the different types. With low voltage rise in operation (UPP) the permissible current load is calculated as follows:
| Fmax = UrUPP x Fr |
for example Ur = 63 V, UPP = 12 V, Fr = 50 V/µsec.
hence Fmax
6312
x 50 = 262.5 V/µsec.When using maximum current ratings, self-heating must be taken into account at higher frequencies, and must not exceed 8 K.
Dissipation (heat losses): The heat dissipated by a capacitor when stressed by non-sinusoidal voltages or when under pulse conditions can be approximately determined from the following formula:
| PV | = Urms 2 x ωC x tanδ |
| PV | = dissipation in Watts (see table 1 for the max. W per K). |
| Urms | = root mean square value of the AC voltage share |
| ω | = 2π x f, where f is the repetition frequency of the pulse waveform. |
| C | = capacitance in Farad |
| tanδ | = dissipation factor corresponding to the frequency of the steepest part of the pulse. |
pulse frequency =
1pulse width
temperature rise in K =
calculated dissipationspecific dissipation
(see table 1)| Printed circuit module PCM (in mm) |
Specific dissipation in Watts per K above the ambient temperature |
| 2.5 5 7.5 10 15 22.5 27.5 37.5 |
0.0025 0.004 0.006 0.0075 0.012 0.015 0.025 0.03 |
Table 1: The data is for ordinary assembly and ventilation conditions avoiding radiant heat within the chassis of the equipment.
In applications where reliability is critical, it is recommended to measure the surface temperature of the capacitor and to take into account that the temperature within that capacitor will be approximately 5 K above the case temperature.
Determining the permissible AC voltage and AC current at given frequencies.
To determine the permissible AC voltage (sinusoidal) for applications in a higher frequency spectrum, graphs showing AC voltage derating with frequency are available for the respective WIMA series. The diagrams refer to a permissible self-heating of:
Δϑ < 10 K.
For the WIMA MKP 10 / 0.01µF / 630VDC/400VAC, for example, this shows - when f = 50kHz - a permissible AC voltage of
Urms = 280 V (graph 2).
Graph 2: Permissible AC voltage in relation to frequency at 10°C internal temperature rise (general guide).
The AC voltage given in the diagrams can also be used to determine the maximum effective current
| XC = 1ω x C = 12π x 50kHz x 0.01 µF |
XC = 318 Ω |
| IC = UCXC = 280 V~318 MΩ |
IC = 0.88 A |
The calculated maximum value of the effective current
| IP = IC x √2 = 0.88 A x √2 | IP = 1.24 A |
Selection example for pulse application capacitors
Determination of the nominal voltage
Calculation is based on an operating temperature < +60°C unless other data is given by the user.
Ur > 350 V
Urms 85 V (referring to AC voltage share)
Selected nominal voltage: 400VDC / 250VAC pin spacing 27.5mm
Permissible voltage gradient
The voltage rise time is
350 V4 µsec
~ 87.5 V/µsec.Value from the table "pulse rise time WIMA FKP 1": 7000 V/µsec.
The calculated voltage gradient is lower than the permissible value shown in the catalogue for this capacitor.
Dissipation
Given:
Urms = 85 V
f = 32 kHz
C = 0.1 µF
The frequency determined from the steepest part of the pulse is:
Pulse width = 15 µsec = 1 cycle.
Hence pulse frequency =
115 x 10-6
~ 66 kHzThe tanδ of WIMA FKP 1 at 66 kHz ~ 10 x 10-4 (Polypropylene graph: Dissipation factor change versus frequency)
Pd = 852 x 2π x 32 x 103 x 0.1 x 10-6 x 10 x 10-4 ~ 0.145 Watts.
The selected capacitor has a pin spacing of 27.5mm
(Selection of capacitors for pulse applications: Table 1, specific dissipation = 0.025 Watts/K) and the temperature rise due to self-heating is:
Temperature rise =
0.145 Watts0.025 Watts/K
~ + 6K.The temperature rise plus the max. ambient temperature = max. permissible operating temperature (taking into account the voltage derating in the (Electrical Data WIMA FKP 1). If the permissible temperature is exceeded, then select a capacitor with a higher voltage rating.
Alternatively, our engineers will submit their recommendations upon receipt of voltage and current oscillogrammes. Questionnaire available on demand at WIMA Sales Office by phone +49 621 86295-0 or e-mail sales@wima.de.
Self-Inductance Depends on Construction Principle
Depending on the construction, an alternating current in the capacitor winding creates a more or less distinctive magnetic field which can be measured as inductance messen lässt.
The tape length of the winding element determines the value of the self-inductance
Modern plastic film capacitors are contacted over the whole end surface of the winding element. In this way the self-inductance of the winding element is short-circuited. The self-inductance is reduced to the PCM (0.8 nH/mm) and the remaining length of the terminating wires (in case of SMD capacitors the distance between the soldering plates).
Average value for practical applications: inductance related to length = 0.8 nH/mm
Example: length of the terminating wires = 2 x 3 mm + PCM
Old Type with High Self-Inductance
The tape length of the winding element determines the value of the self-inductance
Modern WIMA Type
Modern plastic film capacitors are contacted over the whole end surface of the winding element. In this way the self-inductance of the winding element is short-circuited. The self-inductance is reduced to the PCM (0.8 nH/mm) and the remaining length of the terminating wires (in case of SMD capacitors the distance between the soldering plates).
Average value for practical applications: inductance related to length = 0.8 nH/mm
Example: length of the terminating wires = 2 x 3 mm + PCM
WIMA MKS 02 / PCM 2.5 mm
Self-inductance L < 8 nH
WIMA SMD /Size Code 1812
Self-inductance L < 6 nH
Increasing winding lengths in relation to the capacitance result in a large bonding area and guarantee low ESR values.
Thus plastic film capacitors stand out because of their HF properties which are the same as or better than those of ceramic capacitors of comparable size.
Circuit arrangements of capacitors
In parallel
| Ctotal = C1 + C2 + ... |
In series
1Ctotal = 1C1 +1C2 + ... |
Marking of WIMA capacitors
SMD capacitors
Marking of WIMA SMD capacitors was gradually ceased as of July 2003. Identification is possible by the labelling of packages and delivery notes respectively.
Through-Hole Capacitors
In general, WIMA through-hole capacitors are marked on the front side of the box in plain text with brand name, capacitor series, capacitance, nominal voltage, date code and tolerance. Capacitors with PCM smaller than 15 mm will have the tolerance indicated on the reverse. Standard tolerance 20% is not marked.
PCM 2.5mm and PCM 5mm film/foil
PCM 5mm metallized*
| Capacitance | Code |
| 0.01 µF 0.015 µF 0.022 µF 0.033 µF 0.047 µF 0.068 µF |
10n 15n 22n 33n 47n 68n |
| 0.1 µF 0.15 µF 0.22 µF 0.33 µF 0.47 µF 0.68 µF |
µ1 µ15 µ22 µ33 µ47 µ68 |
| 1,0 µF 1.5 µF 2.2 µF 3.3 µF 4.7 µF 6.8 µF |
1µ 1µ5 2µ2 3µ3 4µ7 6µ8 |
| 10 µF | 10µ |
PCM 7.5mm and 10mm
PCM 15mm through 37.5mm
or
or
The series name MKS 2, FKP 3 etc. is composed as follows:
- The first letter indicates the type of construction
"M"= metallized construction
"F"= film/foil construction (brands of other manufacturers are missing this letter) - The second letter "K" stands for plastic film capacitors.
- The third letter indicates the dielectric film used "S"= Polyester (PET) (other manufacturers are using "T")
- The numbers following are WIMA-specific markings.
"P"= Polypropylene (PP)
The cases of 2.5 mm and 5 mm capacitors are too small to imprint with the series type (i.e. MKS 2, FKS 2 etc.). Instead, these capacitors must be identified by different colours of the marking inks.
| PCM 2.5 mm | Case | Marking | Example | ||
| FKP 02 | Red | Black |  |
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| MKS 02 | Red | Silver/Black |  |
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| PCM 5 mm | Case | Marking | Example | ||
| FKS 2 | Red | Silver/Black |  |
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| FKP 2 | Red | Black |  |
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| MKS 2 | Red | Silver/Black/White* |
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| MKP 2 | Red | Black* |
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WIMA MKS 2: (Marking: White)
WIMA MKP 2: (Marking: Black)
Application guide for WIMA capacitors
Overview |
Fields of Applications | ||||||||||
| Automotive | Power | Lighting | Medical | Consumer | Telecom/ Data | New Enegy | |||||
| Product Family | Range Description | Picture | |||||||||
| SMD Capacitors | Size codes 1812 - 6054 SMD-PET/-PEN/-PPS |
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| Miniature Capacitors | PCM 2.5 mm MKS 02, FKP 02 |
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| Film/Foil Capacitors | PCM 5 - 15 mm FKS 2, FKP 2, FKS 3, FKP 3 |
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| Metallized Capacitors | PCM 5 - 52.5 mm MKS 2, MKP 2, MKS 4, MKP 4 |
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| Pulse Capacitors | PCM 7.5 - 52.5 mm MKP 10, FKP 4, FKP 1 |
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| RFI Capacitors | PCM 7.5 - 37.5 mm
MKP-X2, MKP-X1 R, MKP-Y2 |
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| Filter Capacitors | PCM 27.5 - 52.5 mm MKP 4F |
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| Snubber Capacitors | Variable terminations Snubber MKP/FKP |
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| GTO Capacitors | Axial screw connections
GTO MKP |
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| DC-LINK Capacitors | Variable terminations
DC-LINK MKP 4/6/HC Customized |
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| SuperCap Modules | Customized
PowerBlocks |
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Automotive |
Fields of Application | |||||||||||
| Safety | Auxiliaries | Powertrain | Features | |||||||||
| Airbag control unit | Braking system (ABS/ESC) | Tire pressure monitoring unit | HID lamps | Small motor drives (e.g. seats, mirrors windows etc.) | Electrical power steering | Remote keyless entry | DC/DC converter and inverter, Electric drives | Fuel pump, diesel filter control unit | ||||
| SMD Capacitors
0.01 µF - 6,8 µF 63 - 1000 VDC Size codes 1812 - 6054
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SMD-PPS |
SMD-PPS |
SMD-PET |
SMD-PET |
SMD-PET |
SMD-PET |
SMD-PET |
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Film Capacitors
1000 pF - 680 µF 50 - 2000 VDC PCM 2.5 - 52.5 mm
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MKS 02 MKS 2 MKS 4 FKS 2 FKS 3 |
MKS 02 MKS 2 MKS 4 FKS 2 FKS 3 |
MKP 2 MKP 4 |
MKS 02 MKS 2 MKS 4 MKP 2 MKP 4 FKS 2 FKS 3 |
MKP 2 MKP 4 |
MKS 02 MKS 2 MKS 4 |
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| Pulse Capacitors
100 pF - 47 µF 100 - 6000 VDC PCM 7.5 - 52.5 mm
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MKP 10 FKP 4 FKP 1 MKP 2 MKP 4 |
MKP 10 FKP 4 FKP 1 MKP 2 MKP 4 |
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| RFI Capacitors 1000 pF - 10 µF 300 - 440 VAC PCM 7.5 - 37.5 mm
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MKP-X2 MKP-X1 R MKP-Y2 |
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| Filter Capacitors 0.68 µF - 75 µF 230 - 440 VAC PCM 27.5 - 52.5 mm
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MKP 4F |
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| Snubber Capacitors
0.01 µF - 8 µF 630 - 4000 VDC Variable contacts
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Snubber MKP Snubber FKP |
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| DC-LINK Capacitors
1 µF - 8250 µF 400 - 1500 VDC Variable contacts
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DCL MKP 4 DCL MKP 6 DCL HC customized |
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| PowerBlock Modules
Customized
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SuperCap modules for boardnet stabilization and safety backup | SuperCap modules for local power supply | SuperCap modules for recuperation of breaking energy/ power boost |
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Power Electronics |
Fields of Application | ||||||||
| Power Electronics | Features | ||||||||
| Battery charger | Frequency converter | Power supply/ SMPS | UPS | AC filter, harmonic filter | Electronic power meter | ||||
| SMD Capacitors
0.01 µF - 6.8 µF 63 - 1000 VDC Size codes 1812 - 6054
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SMD-PET |
SMD-PET |
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| Film Capacitors
1000 pF - 680 µF 50 - 2000 VDC PCM 2.5 - 52.5 mm
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MKS 02 MKS 2 MKS 4 MKP 2 MKP 4 FKS 2 FKS 3 |
MKS 02 MKS 2 MKS 4 MKP 2 MKP 4 FKS 2 FKS 3 |
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| Pulse Capacitors
100 pF - 47 µF 100 - 6000 VDC PCM 7.5 - 52.5 mm
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MKP 10 FKP 4 FKP 1 MKP 2 MKP 4 |
MKP 10 |
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| RFI Capacitors 1000 pF - 10 µF 300 - 440 VAC PCM 7.5 - 37.5 mm
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MKP-X1 MKP-X2 MKP-Y2 |
MKP-X1 MKP-X2 MKP-Y2 |
MKP-X1 MKP-X2 MKP-Y2 |
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| Filter Capacitors 0.68 µF - 75 µF 230 - 440 VAC PCM 27.5 - 52.5 mm
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MKP 4F |
MKP 4F |
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| Snubber Capacitors
0.01 µF - 8 µF 630 - 4000 VDC Variable contacts
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Snubber MKP |
Snubber MKP |
Snubber MKP |
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| DC-LINK Capacitors
1 µF - 8250 µF 400 - 1500 VDC Variable contacts
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DC-LINK MKP 4 DC-LINK MKP 6 DC-LINK HC customized |
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| SuperCap Modules
customized
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PowerBlock as uninterruptible power supply (UPS) |
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Lighting |
Fields of Application | ||||
| Lighting Industry | Features | ||||
| Electronic ballasts | Energy saving lamps | ||||
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Metallized Capacitors
1000 pF - 680 µF 50 - 2000 VDC PCM 5 - 52.5 mm
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MKP 2
MKS 4 MKP 4 |
MKS 2
MKP 2 MKS 4 MKP 4 |
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| Pulse Capacitors
100 pF - 47 µF 100 - 6000 VDC PCM 7.5 - 52.5 mm
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MKP 10 FKP 4 FKP 1 |
MKP 10 FKP 4 FKP 1 |
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| RFI Capacitors
1000 pF - 10 µF 230 - 440 VAC PCM 7.5- 37.5 mm Class X1, X2, Y2
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MKP-X1
MKP-X2 MKP-Y2 |
MKP-X1
MKP-X2 MKP-Y2 |
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Medical |
Fields of Application | |||||||||
| Medical Equipment | Features | |||||||||
| Imaging equipment (CT, MRT, X-Ray, ultrasound) | Anesthesia equipment | Cleaning equipment | Defibrillation devices | Patient care monitoring (glucose meter, blood gas analyser, telemetry) | Respiration technology | Laser technology | ||||
| SMD Capacitors
0.01 µF - 6.8 µF 63 - 1000 VDC Size codes 1812 - 6054
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SMD-PET |
SMD-PET |
SMD-PET |
SMD-PET |
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Film Capacitors
1000 pF - 680 µF 50 - 2000 VDC PCM 2.5 - 52.5 mm
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MKP 2 MKP 4 |
MKS 02 MKS 2 MKS 4 MKP 2 MKP 4 |
MKS 02 MKS 2 MKS 4 MKP 2 MKP 4 |
MKS 02 MKS 2 MKS 4 MKP 2 MKP 4 |
MKS 02 MKS 2 MKS 4 MKP 2 MKP 4 |
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| Pulse Capacitors
100 pF - 47 µF 100 - 6000 VDC PCM 7.5 - 52.5 mm
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MKP 10 FKP 4 FKP 1 |
MKP 10 FKP 4 FKP 1 |
MKP 10 FKP 4 FKP 1 |
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| RFI Capacitors
1000 pF - 10 µF 300 - 440 VAC PCM 7.5 - 27.5 mm
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MKP-X2
MKP-X1 R MKP-Y2 |
MKP-X2 MKP-X1 R MKP-Y2 |
MKP-X2 MKP-X1 R MKP-Y2 |
MKP-X2 MKP-X1 R MKP-Y2 |
MKP-X2 MKP-X1 R MKP-Y2 |
MKP-X2 MKP-X1 R MKP-Y2 |
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| Filter Capacitors 0.68 µF - 75 µF 230 - 440 VAC PCM 27.5 - 52.5 mm
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MKP 4F |
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| Snubber Capacitors
0.01 µF - 8 µF 630 - 4000 VDC Variable terminations
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Snubber
MKP Snubber FKP |
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| GTO Capacitors
1.0 µF - 100 µF 400 - 2000 VDC Axial screw connection
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GTO MKP |
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| SuperCap Modules
customized
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PowerBlock |
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Consumer |
Fields of Applications | |||||||||
| Consumer and Household Electronics | Features | |||||||||
| High-end audio systems | Amplifier | LCD / Plasma TVs | Set top boxes | Video systems | Control units for home applications | White goods (induction cooker, ignition units etc.) | ||||
| SMD Capacitors
0.01 µF - 6.8 µF 63 - 1000 VDC Size codes 1812-6054
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SMD-PPS |
SMD-PET |
SMD-PET |
SMD-PET |
SMD-PET |
SMD-PET |
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Film Capacitors
27 pF - 680 µF 50 - 2000 VDC PCM 2.5 - 52.5 mm
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MKS 02 |
MKS 02 MKS 2 MKS 4 MKP 2 MKP 4 FKP 02 FKP 2 FKP 3 |
MKP 2 MKP 4 |
MKS 02 MKS 2 MKS 4 |
MKS 02 |
MKS 02 MKS 2 MKP 2 MKP 4 FKS 2 FKS 3 |
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| Pulse Capacitors 100 pF - 47 µF 100 - 6000 VDC PCM 7.5 - 52.5 mm
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MKP 10 | MKP 10 | MKP 10 | MKP 10 FKP 4 FKP 1 |
MKP 10 FKP 4 FKP 1 |
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| RFI Capacitors 1000 pF - 10 µF 300 - 440 VAC PCM 7.5 - 37.5 mm
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MKP-X1 MKP-X2 MKP-Y2 |
MKP-X1 MKP-X2 MKP-Y2 |
MKP-X1 MKP-X2 MKP-Y2 |
MKP-X1 MKP-X2 MKP-Y2 |
MKP-X1 MKP-X2 MKP-Y2 |
MKP-X1 MKP-X2 MKP-Y2 |
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| Snubber Capacitors 0.01 µF - 8 µF 680 - 4000 VDC Variable terminations
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Snubber MKP Snubber FKP |
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Telecom/ |
Fields of Application | ||||||||
| Telecommunication / Data Processing | Features | ||||||||
| Power supply | Splitter | Data processing systems (server etc.) | Network devices (router, switcher, hubs, modems) | Wireless communication (WLAN, UMTS etc.) | Memory backup | ||||
| SMD Capacitors
0.01 µF - 6.8 µF 63 - 1000 VDC Size codes 1812-6054
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SMD-PET |
SMD-PET |
SMD-PET |
SMD-PET |
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Film Capacitors 1000 pF - 680 µF 50 - 2000 VDC PCM 2.5 - 52.5 mm
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MKS 02 MKS 2 MKS 4 MKP 2 MKP 4 |
MKS 02 MKS 2 MKS 4 MKP 2 MKP 4 FKS 2 FKS 3 |
MKS 02 MKS 2 MKS 4 MKP 2 MKP 4 FKS 2 FKS 3 |
MKS 02 MKS 2 MKS 4 MKP 2 MKP 4 FKS 2 FKS 3 |
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| Pulse Capacitors 100 pF - 47 µF 100 - 6000 VDC PCM 7.5 - 52.5 mm
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MKP 10
FKP 4 FKP 1 |
MKP 10 FKP 4 FKP 1 |
MKP 10 FKP 4 FKP 1 |
MKP 10 FKP 4 FKP 1 |
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| RFI Capacitors 1000 pF - 10 µF 300 - 440 VAC PCM 7.5 - 37.5 mm
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MKP-X1 MKP-X2 MKP-Y2 |
MKP-X1 MKP-X2 MKP-Y2 |
MKP-X1 MKP-X2 MKP-Y2 |
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| SuperCap Modules
customized
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PowerBlock |
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New Energy |
Fields of Application | ||||||
| New Energy | Features | ||||||
| Energy storage | Converter | Power supply | UPS | Grid interface | |||
| Pulse Capacitors
100 pF - 47 µF 100 - 6000 VDC PCM 7.5 - 52.5 mm
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MKP 10 FKP 4 FKP 1 MKP 2 MKP 4 |
MKP 10 FKP 4 FKP 1 MKP 2 MKP 4 |
MKP 10 FKP 4 FKP 1 MKP 2 MKP 4 |
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| Filter Capacitors 0.68 µF - 75 µF 230 - 440 VAC PCM 27.5 - 52.5 mm
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MKP 4F | MKP 4F |
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| Snubber Capacitors 0,01 µF - 8 µF 630 - 4000 VDC Variable terminations
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Snubber
MKP Snubber FKP |
Snubber
MKP Snubber FKP |
Snubber
MKP Snubber FKP |
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| GTO Capacitors
1µF - 100 µF 400 - 2000 VDC Axial screw connection
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GTO MKP | GTO MKP | GTO MKP |
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| DC-LINK Capacitors
1 µF - 8250 µF 400 - 1500 VDC Variable terminations
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DC-LINK MKP 4 DC-LINK MKP 6 DC-LINK HC customized |
DC-LINK MKP 4 DC-LINK MKP 6 DC-LINK HC custumized |
DC-LINK MKP 4 DC-LINK MKP 6 DC-LINK HC customized |
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| SuperCap Modules
customized
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PowerBlock (e.g. in photovoltaic systems) | PowerBlock (e.g. pitch control in wind turbine systems) | PowerBlock for emergency backup systems |
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WIMA SMD capacitors
| Fields of Application: Automotive, Power, Medical, Consumer, Telecom/Data | |||||||||||||
| Product Type | Application Function | Circuit Application | Waveform | Requirements | Special Characteristics | ||||||||
| SMD-PET
SMD-PEN SMD-PPS |
Blocking/Coupling
High-pass filter:
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| Bypass/Decoupling
Low-pass filter:
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Smoothing
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| SMD-PPS | Band-pass filter (e.g. audio, TV)
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Band-stop filter (e.g. audio, TV)
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WIMA film capacitors (PCM 2.5 – 52.5 mm)
| Fields of Application: Automotive, Power, Lighting, Medical, Consumer, Telecom/Data, New Energy | |||||||||||||
| Product Type | Application Function | Circuit Application | Waveform | Requirements | Special Requirements | ||||||||
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MKS 02, FKS 2, MKP 4 (HF-coupling/ decoupling) |
Blocking/Coupling
High-pass filter:
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Metallized film capacitors (MK-types):
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| Bypass/Decoupling
Low-pass filter:
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MKS 02, |
Smoothing
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FKP 02,
MKP 2, |
Band-pass filter (e.g. audio, TV)
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Band-stop filter (e.g. audio, TV)
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FKP 02, MKP 2, |
Timing (e.g. signal light)
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FKP 02, MKP 4 |
Sample & hold (e.g. amplifier) analogue-digital converter:
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Peak voltage detectors
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WIMA pulse duty capacitors (PCM 7.5 – 52.5 mm)
| Fields of Application: Automotive, Power, Lighting, Medical, Consumer, Telecom/Data, New Energy | |||||||||||||||
| Product Type | Application Function | Circuit Application | Waveform | Requirements | Special Characteristics | ||||||||||
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MKP 10
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Fly-back (e.g. monitors, TV)
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S-correction (smoothing)
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Energy storage (e.g. ballasts)
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Oscillating circuit Resonant system (LC):
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Snubbing (e.g. relay)
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WIMA EMI suppression capacitors
| Fields of Application: Automotive, Power, Lighting, Medical, Consumer, Telecom/Data, New Energy | |||||||||||||
| Product Type | Application Function | Circuit Application | Waveform | Requirements | Special Characteristics | ||||||||
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MKP-X2 MKP-X1 R MKP-Y2 |
EMI suppression
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MKP-X2 |
Voltage dropper
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Filter capacitors
| Fields of Application: Automotive, Power, Medical, New Energy | |||||||||||
| Product Type | Application Function | Circuit Application | Waveform | Requirements | Special Characteristics | ||||||
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MKP 4F |
Voltage Dropper
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WIMA Snubber capacitors
| Fields of Application: Automotive, Power, Medical, Consumer, New Energy | |||||||||||||
| Product Type | Application Function | Circuit Application | Waveform | Requirements | SpecialCharacteristics | ||||||||
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Snubber MKP
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Energy storage
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Snubbing (e.g. IGBT)
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WIMA GTO capacitors
| Fields of Application: Power, New Energy | |||||||||||||
| WIMA products | Application Function | Circuit Application | Waveform | Requirements | Special Characteristics | ||||||||
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GTO MKP
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Energy storage
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Snubbing (e.g. GTO-thyristor)
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WIMA DC-LINK capacitors
| Fields of Application: Automotive, Medical, Power, New Energy | |||||||||||||
| Produc Type | Application Function | Requirements | Special Characteristics | ||||||||||
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DC-LINK MKP 4 |
Energy buffer e.g. in:
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WIMA PowerBlocks
| Fields of Application: Automotive (Passenger Cars, Trucks, Busses, Military Vehicles, and Forklifts) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Application Function | Figure | Requirements | Special Characteristics | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Recuperation of Braking Energy/Power Boost
Peak-Load Levelling
Local Power Supply
Boardnet Stabilisation
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Combination with Batteries in Hybrid and Electric Cars
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Cranking of Engines
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Replacement of Starter Batteries
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| Fields of Application: Transportation (Trains, Tram, Subway ) | |||||||||||||||||||||||||||||||||||||
| Application Function | Figure | Requirements | Special Charecteristics | ||||||||||||||||||||||||||||||||||
Recuperation of Braking Energy/Power Boost
Peak-Load Levelling
Short-Term Energy Storage
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Motor Start
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| Fields of Application: Power Supply (UPS); Telecommunication/Data Processing (Memory Backup) | ||||||||||||||||||
| Application Function | Figure | Requirements | Special Characteristics | |||||||||||||||
UPS
Peak-Load Levelling
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UPS-Emergency Backup in Hospitals, Telecommunication Systems, Oil and Gas Extraction
(cost-intensive processes)
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Short-Term Energy Storage
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Memory Backup - On-Board Logic
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| Fields of Application: New Energy (Wind, Solar Systems) | ||||||||||||||||||||||||||||
| Application Function | Figure | Requirements | Special Characteristics | |||||||||||||||||||||||||
Power Supply
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Short-Term Energy Storage
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Substitution of obsolete polycarbonate (PC) capacitors
After the discontinuation of Polycarbonate film (end of 2000) as a capacitor dielectric by the only manufacturer, Bayer AG/Germany, we have removed all MKC ranges (metallized construction) and FKC ranges (film/foil construction) using this capacitor film from our range of products latest after inventory of film has run out.
However, the question of which capacitors can be used to replace the PC series is still of interest. The following comparisons may be of assistance in making decisions.
The special feature of Polycarbonate (PC) capacitors is the almost constant course of capacitance drift versus temperature and the suitability for special applications in the field of higher frequencies respectively.
Note: size comparisons between series are possible for the most parts.
Note: size comparisons between series are possible for the most parts.
However, the question of which capacitors can be used to replace the PC series is still of interest. The following comparisons may be of assistance in making decisions.
The special feature of Polycarbonate (PC) capacitors is the almost constant course of capacitance drift versus temperature and the suitability for special applications in the field of higher frequencies respectively.
Capacitance change with temperature
Dissipation factor change with frequency
Substitution by Polyester (PET) Capacitors
Capacitance change with temperature
Results: In the field of normal application temperature 0/+20 to +80°C Polyester (PET) shows a comparable linearity of the capacitance course in the positive field in comparison with Polycarbonate (PC) which shows a slightly negative course. The capacitance inconstancy versus time is basically identical with both dielectrics.
Substitution suggestions for metallized capacitors:
| Obsolete WIMA type | PCM | Suggested WIMA type | PCM | Replace also obsolete competitor series |
| WIMA MKC 02 | 2.5 | WIMA MKS 02 | 2.5 | |
| WIMA MKC 2 | 5 | WIMA MKS 2 | 5 | MKC 1858 / CMK |
| WIMA MKC 3 | 7.5 | WIMA MKS 4 | 7.5 | CMK |
| WIMA MKC 4 | >10 | WIMA MKS 4 | >10 | MKC 1862 / MKC 344 / CMK |
Substitution suggestions for film/foil capacitors:
| Obsolete WIMA type | PCM | Suggested WIMA type | PCM | Replace also obsolete competitor series |
| WIMA FKC 2 | 5 | WIMA FKS 2 | 5 | KC 1850 / CFR (CMK) |
| WIMA FKC 3 | >7.5 | WIMA FKS 3 | >7.5 | CMK |
Substitution suggestions for Polypropylene (PP) capacitors:
Capacitance change with temperature
Dissipation factor change with frequency
Results: in comparison to Polycarbonate (PC), Polypropylene (PP) has a lower dissipation factor throughout the course of the whole temperature field.
Substitution suggestions for metallized capacitors:
| Obsolete WIMA type | PCM | Suggested WIMA type | PCM | Replace also obsolete competitor series |
| WIMA MKC 2 | 5 | WIMA MKP 2 | 5 | MKC 1858 / CMK |
| WIMA MKC 3 | 7.5 | WIMA MKP 4 | 7.5 | CMK |
| WIMA MKC 4 | >10 | WIMA MKP 4 | >10 | MKC 1862 / MKC 344 / CMK |
| WIMA MKC 10 | >7.5 | WIMA MKP 10 | >7.5 |
Substitution suggestions for film/foil capacitors:
| Obsolete WIMA type | PCM | Suggested WIMA type | PCM | Replace also obsolete competitor series |
| WIMA FKC 02 | 2.5 | WIMA FKP 02 | 2.5 | |
| WIMA FKC 2 | 5 | WIMA FKP 2 | 5 | KC 1850 / CFR (CMK) |
| WIMA FKC 3 | >7.5 | WIMA FKP 3 | >7.5 | CMK |
Radial box versus radial dipped capacitor technologies
Radial Box versus Radial Dipped Capacitor Technologies
The origins of radial box film capacitor technology lie in radial dipped film technology, which was first developed by WIMA and other European manufacturers in the early-middle 1960s. The radial design offered obvious advantages over the axial design. These included board real estate savings as well as improved electrical performance (lower ESR and self inductance) and did not require the pins to be bent in order for the part to be inserted on the printed circuit board.
1962 Radial dipped
- Improved electrical performance
- Lower ESR and self-inductance
- Less space required on PC-board in comparision to axial leaded devices
- Easy plug-in mounting.
1963 Moulded case
- Defined case-size
- Humidity protection
- Robotic insertion
- Less space required on PC-board
1970 Resin potted case
- Improved humidity protection
- Reduced mechanical stress on pins/solder joints due to support on edge of box
- Good self-healing properties due to encapsulation without pressure
1974 Box type
- Increased humidity protection
- Reduced outside dimensions
- Easy robotic insertion
- Seating plane defined through „standoff-feet“
- Excellent self-healing properties due to encapsulation without pressure
- Standardized sizes
Humidity Protection
The poreous epoxy coating of radial dipped film capacitors cannot be expected to provide reliable humidity protection where moderate to severe humidity conditions exist, even when potting compound such as bitumen is used. In addition, since there is no clearly defined seating plane, components rest on the "laquered pants" that can and do develop fissures at the pin exit points when parts are automatically inserted, thus further compromising their ability to resist the effects of humidity.
Box type
- Two casting steps guarantee high humidity protection
- Homogenous encapsulation without air enclosures
- Case and pin exit points secure from high humidity
- Additional protection by cast sealing is not necessary
Dipped version
- Very porous coating with visible air enclosures
- Mechanical stress during insertion leads to cracks around the pin exit points
- Insufficient humidity protection due to thin and irregular encapsulation
- Bitumen or tar casting does not provide the expected protection
Uniform Dimensions
Radial box film capacitor provides uniform dimensions for purposes of optimizing space and second sourcing. Further, it allows for greater flexibility in automatic insertion including robotic insertion of larger parts.
Box type
- All dimensions clearly defined
- Allows for close placement of parts
- Easy second source because of standardized box size
Dipped version
- Only pin spacing is defined
- All other dimensions are undefined
- No standardized body sizes (second source)
- Need of additional space between the parts due to variations of pin exit points and body dimensions
Exact Setting on PC-Board
Since radial dipped film capacitors rest on their pins rather than on the case or "standoff-feet", any vibration that the capacitor element may be experiencing will be transmitted through the pins to the solder joints. This is of particular concern in AC applications where self-generated electro-mechanical vibrations accelerate the ageing of the solder joints.
Box type
- Capacitors rest on „standoff-feet“
- No stress on pins
- Electro-mechanical vibrations do not impact solder joints
- Exact setting on PC-board
- Small footprint on PC-board
Dipped version
- Capacitors rest on solder joints
- Electro-mechanical vibrations can lead to accelerated ageing of solder joints
- More space required to avoid short circuits
Flammability Resistance
The extremely thin covering, plus the presence of air pockets contained within the coating, makes the dipped film packaging of doubtful value with regard to passive and active flammability. This is especially the case when the applications does not use any potting compound. On the other hand, the mechanical integrity of the box and cast resin technology provides a high level of flammability resistance when the capacitor is used in AC applications such as in a power line filter or in series with the lamp.
Basically all plastic film dielectrics are flammable. Only encapsulation protects the capacitor against fire.
Box type
- Uniform thickness of encapsulation
- High flammability protection in accordance with UL 94 V-0
- No cast sealing necessary.
- Epoxy material may or not be passively flammable
- Thin coating gives quick access to winding element after short application of flame
- Air bubbles in coating stimulate the flames
- Higher fire risk when tar is used
When radial box film capacitors are used, the need for potting disappears, since the box capacitor provides sufficient humidity and flammability protection, as well as mechanical integrity, in the face of externally or internally generated shock and vibration.
The need for qualified capacitor applications to operate for many years without the maintenance or replacement in often times difficult environmental and operating conditions, makes it critical that the components meet the highest standards of packaging technology. Without such standards, safe and reliable operation over the life of the product cannot be guaranteed. The box film technology is designed to meet this challenge both in radial and SMD version.
Snubber capacitors for IGBT circuits
The trend of modern semiconductor technology towards increasingly powerful applications results in the fact that switched currents and voltage levels are continuously increased and that simultaneously the switching speed is also increasing markedly.
The developments in the area of power semiconductors include the component group IGBT (Insulated Gate Bipolar Transistor) or IGBT modules.
The switching capacity with shortest switching times which can be realized using IGBTs necessitates an extremely low-inductance circuit design. Even the low self-inductance of the power bus may induce dangerous voltage overshoots between collector and emitter which may result in the destruction of the valuable power semiconductors.
Typical voltage overshoot during switch-off.
To protect the components, so-called snubber suppressor circuits are used. The most important component in this respect is a low-inductance pulse capacitor in order to attenuate or cut off peak voltages. In general, three basic snubber circuits are used with IGBTs.
Circuit A Capacitor |
Circuit B Capacitor-resistor-diode |
Circuit C Capacittor-resistor-diode |
In this context, the capacitor serves to suppress dangereous induced voltages which are produced during switching of the often very high currents. The most important criteria in selecting such capacitors are
- low self-inductance
- low ESR
- high pulse load capability
- low loss factor
Based on long experience with Polypropylene pulse capacitors in all conceivable applications, the series WIMA Snubber MKP and WIMA Snubber FKP were developed to meet the demands of high-power converter technology and are state-of-the-art components with regard to quality, reliability, and electrical performance.
The WIMA Snubber technology is unique
- Low-loss Polypropylene dielectric
- High pulse load capability due to double-sided metallization or film/foil construction
- High voltage / overvoltage strength
- Low inductance design achieved by end-surface contacting
- Various connection configurations
- Direct-contact terminals for safe contact at high continuous current load
- Flame-retardant plastic case, UL 94 V-0
- Production sites ISO 9001:2015 certified.
WIMA environmental policy
All WIMA capacitors, irrespective of whether through-hole devices or SMD, are made of environmentally friendly materials. Neither during manufacture nor in the product itself any toxic substances are used, e.g.
- Lead
- PCB
- CFC
- Hydrocarbon chlorid
- Chromium 6+
- carton
- cardboard
- adhesive tape made of paper
- polystyrene
- adhesive tapes made of plastic
- metal clips