Technical Note
Judicious Use of Aluminum Electrolytic Capacitors
Contents

1. Overview of Aluminum Electrolytic Capacitors
1－1

Basic Model of Aluminum Electrolytic Capacitors

1－2

Structure of Aluminum Electrolytic Capacitors

1－3

Features of Capacitor Materials

1－4

Manufacturing process

2. Basic Performance2－1

Basic Electrical Characteristics

2－2

Frequency Characteristics of Impedance

3. Reliability
4. Failure Modes
5. Lifetime of Aluminum Electrolytic Capacitors
5－1

Ambient Temperature Effect on Lifetime

5－2

Applying Voltage Effect on Lifetime

5－3

Ripple Current Effect on Lifetime

5－4

Charge and Discharge Operation Effect on Lifetime

5－5Inrush Current

5－6

Abnormal Voltage Effect on Lifetime

6. Effect of Halogens
6－1

Effect of Flux

6－2

Cleaning Agents

6－3

Adhesive and Coating Materials

6－4

Effect of Fumigation

7. Recovery Voltage
8. Storage
9. Tips for Selecting Capacitors Appropriate for Individual Applications
9－1

Input Filtering Capacitors for Switching Mode Power Supplies

9－2

Output Filtering Capacitors for Switching Mode Power Supplies

9－3

Filtering Capacitors for Inverter Main Circuits

9－4

Capacitors for Control Circuits

9－5

Photoflash Capacitors

TECHNICAL NOTE

1．Overview of Aluminum Electrolytic CapacitorsdDielectric

1-1 Basic Model of Aluminum Electrolytic Capacitors
S

Capacitors are passive components. Among the various kindsof capacitors, aluminum electrolytic capacitors offer larger CV
product per case size and lower cost than the others.
In principles of capacitor, its fundamental model is shown in Fig.
1 and its capacitance (C) is expressed by Equation (1) below:εrεrS（F） …………………………………（1）dεr ：Dielectric constant
Ｓ：Surface area of dielectric（m2）ｄ：Thickness of dielectric（m）

C ＝ 8.854 × 10 － 12

Fig-1

Basic model of capacitor

Separator

Anode foil

Equation (1) shows that the capacitance (C) increases as thedielectric constant (εr) and/or its surface area (S) increases and/or
the dielectric thickness (d) decreases.
An aluminum electrolytic capacitor comprises a dielectric layer ofaluminum oxide (Al2O3), the dielectric constant (εr) of which is 8 to
10. This value is not significantly larger than those of other types ofcapacitors.
However, by extending the surface area (S) of the aluminum foil
electrode by means of etching, and by electrochemically forming athinner but highly voltage-withstandable layer of oxide layer dielectric, the aluminum electrolytic capacitor can offer a larger CV product per case size than other types of capacitors.
A basic model of aluminum electrolytic capacitor is shown in Fig. 2.
An aluminum electrolytic capacitor comprises:

Cathode foil

Dielectric（Al2O3）

Electrolyte
DA

DC

LA

LC
CA
RA

R

CC
RC

CA、CC：Capacitance due to anode and cathodes foils
DA、DC：Diode effects due to oxide layer on anode and cathode foils
LA、LC ：Inductance due to anode and cathode terminals
R：Resistance of electrolyte and separator
RA、RC：Internal resistance of oxide layer on anode and cathode foils

Anode …Aluminum foil
Dielectric…Electrochemically formed oxide layer (Al2O3) on
the anode
Cathode …A true cathode is electrolytic solution (electrolyte).

Fig-2

Other component materials include a paper separator that
holds electrolyte in place and another aluminum foil that functions as a draw-out electrode coming into contact with the true
cathode (electrolyte).
In general, an aluminum electrolytic capacitor is asymmetricalin structure and polarized. The other capacitor type known as abi-polar (non-polar) comprises the anodic aluminum foils forboth electrodes.

Basic model and equivalent circuit of aluminumelectrolytic capacitor

Lead Wire (Terminal)
Aluminum Tab
Separator Paper
Cathode Foil
Anode Foil

1-2 Structure of Aluminum Electrolytic Capacitor
The aluminum electrolytic capacitor has, as shown in Fig. 3, aroll of anode foil, paper separator, cathode foil and electrodeterminals (internal and external terminals) with the electrolyte
impregnated, which is sealed in an aluminum can case with asealing material.
The terminal draw-out structure, sealing material and structure
differ depending on the type of the capacitor.
Figure 4 shows typical examples.

Fig-3

Basic model of element
Vent

Element
SleeveCan

Can

SleeveCoated Can

Element

Rubber Seal

Element

Aluminum Tab
Lead Wire（Terminal）

Rubber Seal

Aluminum Tab

Aluminum Tab
Terminal Plate

Sealing Material
Lead Wire（Terminal）
Terminal（Surface Mount Type）（Radial Lead Type）

Fig-4（Snap-in Type）

Construction of Aluminum Electrolytic Capacitors

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CAT. No. E1001Y 2024

TECHNICAL NOTE
1-3

Features of Capacitor Materials

1-4 Manufacturing Process

Aluminum, which is main material in an aluminum electrolytic
capacitor, forms an oxide layer (Al2O3) on its surface when thealuminum is set as anode and charged with electricity in electrolyte.
The aluminum foil with an oxide layer formed thereon, as
shown in Fig. 5, is capable of rectifying electriccurrent in electrolyte. Such a metal is called a valve metal.

① Etching (for extending the surface area)
This etching process serves toextend the surface area of thealuminum foil. This is an AC or
DCcurrent-employed electrochemical process for etching the foil
surface in a chloride solution.

Aluminum basematerial

Etching Model
Al2O3

I

② Formation (for forming a dielectric)
0

V

This is a process for forming adielectric layer (Al 2 O 3 ), which isnormally performed on the anodealuminum foil.

Forming Model③ Slitting
Fig-5

V-I characteristics of aluminum oxide<Anode aluminum foil>First, the foil material is electromechanically etched in a chloride
solution to extend the surface area of the foil.
Secondly, for the foil to form an aluminum oxide layer (Al2O3) as adielectric, more than the rated voltage is applied to the foil in a solution such as ammonium borate. This dielectric layer is as dense andthin as 1.1 - 1.5 nm/volt and showing a high insulation resistance(108 - 109 Ω/m).
The thickness of the oxide layer determines the withstand voltage
according to their direct proportional relationship. For the etchingpits to be shaped to the intended thickness of the oxide layer, the pit
patterns have been designed to have efficient surface area extension depending on the intended withstand voltage (see Fig. 6)<Cathode aluminum foil>
An etching process is performed to the cathode aluminum foil aswell as the anode foil. However, the formation process for oxide
layer is generally not performed. Therefore, the surface of thecathode foil only has an oxide layer (Al2O3) that has spontaneously formed, which gives a withstand voltage of about 0.5 volt.
Low Voltage Foil

High Voltage Foil

Blade

This is a process for slitting aluminum foils (both the anode andcathode) and paper separators to
the specified product size.

④ WindingThis is a process for rolling a set ofanode and cathode foils into a cylindrical form with a paper separator
inserted between them. During thisprocess, an inner terminal (called atab) is attached to each of the aluminum foils. The roll made at thisprocess is called a capacitor element.

Fig-6（Fracture surface of DC etched foil）
Replica

Cross section of aluminum etched foil（SEM)<Electrolyte>
The electrolyte, an ion-conductive liquid functions as a true
cathode coming into contact with the dielectric layer on the surface of the anode foil. The cathode foil serves as a collector
electrode to connect the true cathode with the external circuit.
Electrolyte is an essential material that controls the performance of the capacitor (temperature characteristics, frequency
characteristics, service life, etc.).
<Paper separator >The separator maintains uniform distribution of the electrolyte andkeeps the anode-to-cathode foil distance unchanged.
<Can case and sealing materials>
An aluminum can case and seal materials mainly consisting of
rubber are used for the purpose of keeping airtightness.

Lead Wire(Terminal) Anode Foil
Separator Paper

Cathode Foil

Electrolyte⑤ Impregnation
This is a process for impregnating
the element with electrolyte as atrue cathode. The electrolyte alsofunctions to repair the dielectric
layer.

⑥ Sealing

Impregnation

Aluminum Can

This process seals the element
using the aluminum can case andsealing materials (rubber,rubberlined cover, etc.) for keeping thecase airtight.

（Fracture surface of AC etched foil）

Slitting Model

Element⑦ Aging (reforming)
The process of applying voltage to a
post-sealed capacitor at high temperature is called “aging”. This
serves to repair defective dielectrics
that have been made on the foil
during the slitting or winding process.

Rubber⑧ 100% inspection and packaging
After the aging, all products shallundergo testing for checking theirelectrical characteristics with chiptermination, lead reforming, taping
etc. finished, and then be packaged.

⑨ Outgoing inspections
Outgoing inspections are performed as per standard inspection
procedures.

⑩ Shipment

Product specifications in this catalog are subject to change without notice.Request our product specifications before purchase and/or use. Please use our products based on the information contained in this catalog and product specifications.

CAT. No. E1001Y 2024

TECHNICAL NOTE

２．Basic Performance
2-1-1

Capacitance

The larger the surface area of an electrode is, the higher thecapacitance (capacity for storing electricity) is. For aluminumelectrolytic capacitors, the capacitance is measured under the
standard measuring conditions of 20°C and a 120Hz AC signalof about 0.5V. Generally, as the temperature rises, the capacitance increases; as the temperature decreases, the capacitance decreases (Fig. 7). With a higher frequency, the capacitance is smaller; with a lower frequency, the capacitance islarger (Fig. 8).

Tanδ( also called tangent of loss angle or dissipation factor)(Fig. 9) is a simplified model of the equivalent circuit shown in(Fig. 2). For an ideal capacitor with an equivalent series resistance of R = 0, the tanδ shown in (Fig. 10) is zero. For an
aluminum electrolytic capacitor, the equivalent series resistance(R) is not zero due to the presence of resistance of the electrolyte and paper separator and other contact resistances. 1/ωC
and R are correlated as shown in (Fig. 10) and Equation (2).
R

Fig-9

L

-60

-40

-20

0

20

Fig-7

60

80

100

120

Temperature Characteristics of CapacitanceEx. 35V470µF Radial Lead Type at 105℃

20
10
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100

20

100

Fig-8

1k

10k
Frequency(Hz)

100k

1M

Frequency Characteristics of CapacitanceEx. 35V470µF Radial Lead Type at 105℃
1C

Simplified equivalent circuit

0.1

0.01
-60

-40

-20

0

20

1/ωC δ
R

Fig-1040

Temperature(℃)

tanδ

2-1-2

Capacitance Change (%)

Basic Electrical Characteristics

Capacitance Change (%)

2-1

Ex. 35V470µF Radial Lead Type at 105℃
20
15
10
5
0
-5
-10
-15
-20
-25
-30
-35
-40

40

60

80

100

120

Temperature(℃)

Fig-11

Temperature Characteristics of tanδDissipation Factor (tanδ)
100

2-1-3

Leakage Current (µA)

Rtan δ＝＝ωCR …………………………………（2）
1/ ωC
ω：2πf
π＝Circular constant、f：Frequency（f ＝ 120Hz）

Leakage Current (LC)

80

60

40

20

As a feature of an aluminum electrolytic capacitor, when DC
voltage is applied to it, the oxide layer that acts as a dielectricin the electrolyte allows a small amount of electric current toflow in it. The small amount of current is called a leakage current (LC). An ideal capacitor does not allow the leakage current
to flow (this is not the case for charging current).

0

0

20

40

60

80

100

120

Time (sec)

Leakage Current (µA)

Fig-12The leakage current (LC) changes with time as shown in (Fig. 12).
Note that LC, decreasing with time, will reach a steady-statevalue. Therefore, the specifications of LC are defined as a value
measured several minutes after the beginning of the applicationof the rated voltage at 20°C. As the temperature rises, the LC
increases; as the temperature decreases, the LC decreases(Fig.13). As the applied voltage decreases, the LC decreases.

102

2 minutes
10
5 minutes－40 －25

Fig-13

Leakage Current vs. Time

0

20
60
Temperature(℃)

85

Temperature Characteristics of Leakage Current

Product specifications in this catalog are subject to change without notice.Request our product specifications before purchase and/or use. Please use our products based on the information contained in this catalog and product specifications.

CAT. No. E1001Y 2024

TECHNICAL NOTE
2-2 Frequency Characteristics of Impedance
When a capacitor is applied with a voltage with the frequencychanged, the impedance (Z), a factor of preventing the AC current changes as shown in (Fig. 14). This is the impedance-frequency characteristics of the capacitor.

R（

R2＋ ωL－

1
ωC） …………………………………（3）2

Impedance・ESR (Ω)

Z

0.1

0.01

ESR
ωL

1／ωC
0.001
100

Fig-14

1k

10k
100k
Frequency(Hz)1M

Factor of Impedance Frequency

100

10

Impedance (Ω)

Z＝

C

1

(Fig. 9) is a simplified model of an equivalent circuit of analuminum electrolyte capacitor. (Fig. 14) shows dotted lines
representing a breakdown of the impedance-frequency characteristic curve into components (C, R and L). As can be seen inthis figure, the impedance-frequency characteristics are a composition of C, R and L frequency characteristics.
The value 1/ωC shows the pure capacitive reactance graphically presented by a straight line going downward at an angleof 45°, and ωL shows the pure inductive reactance graphicallypresented by a straight line going upward at 45̊. R shows theequivalent series resistance (ESR). At a range of lower
frequencies, the R curve goes downward due to the dielectricloss frequency-dependence. At a range of higher frequencies,
the R curve tends to be almost flat since resistance of electrolyte and paper separator is dominant and independent on
frequency. Equation (3) shows this tendency.

L

1

0.1
Aluminum Electrolytic Capacitors
Film Capacitors
Multilayer Ceramic Capacitors

Because the impedance characteristics of an aluminum electrolyte capacitor depend on resistance of the electrolyte andpaper separator, the Z value at the self-resonant frequency
tends to be relatively higher, as shown by the solid line in (Fig.
15). The resistance of the electrolyte varies depending on temperature: as the temperature rises, the impedance decreases;
and as the temperature decreases, the impedance increases,
as shown in (Fig. 16).

0.01
100

1k

10k

100k

1M

Frequency(Hz)Fig-15Frequency Characteristics of each Capacitors Impedance

Ex. 35V470µF Radial Lead Type10

Impedance・ESR (Ω)

1
Impedance
ESR
－40℃

0.1
20℃
105℃

0.01
100

Fig-161k

10k
Frequency(Hz)

100k

1M

Temperature and Frequency Characteristics of Impedance・ESR

Product specifications in this catalog are subject to change without notice.Request our product specifications before purchase and/or use. Please use our products based on the information contained in this catalog and product specifications.

CAT. No. E1001Y 2024

TECHNICAL NOTE

３．Reliability
For designing the device with aluminum electrolytic capacitors, a failure
rate and useful life are necessary to be considered for their reliability.
The failure rate of aluminum electrolytic capacitors is approximated by
the bathtub curve shown in (Fig.17).
ac<Catastrophic failure>This is a failure mode that completely destroys the function of thecapacitor such as short circuit and open circuit failure.
<Wear-out failure>This is a failure mode where the electrical parameters of thecapacitor gradually deteriorate and fail. The criteria for determining if this failure has occurred depend on the purpose of a device.
For each series of capacitors, the following electrical parameters
have been defined as criteria in the specifications of Endurance inthe catalogs or product specifications:
・Change in capacitance・Tanδ・Leakage current
Failure rates are often measured in units of % per 1000 hours(10-5/hour). For higher reliability devices designed with a smaller
failure rate, units of Failure In Time (FIT) (10-9/hour) is used.
Aluminum electrolytic capacitors are considered as componentsof wear-out failure mode, the electrical characteristics of which
gradually deteriorate and their failure rate increases with time. In
general, the failure rate in FIT is determined by total componenthours (product of the number of tested components and test
hours).
Due to the definition of FIT, the same FIT rate can be calculated inboth cases of testing on the large number of tested components
and also testing for long test periods of time. However, thesecases mean differently for aluminum electrolytic capacitors. Using
the failure rate is not suited to express the reliability of aluminumelectrolytic capacitors, but the electrical characteristics based
lifetime in hour should be considered to express the reliability.
Also, there are MTBF (Mean Time Between Failures) and MTTF
(Mean Time To Failure) to express reliability. The latter is applicable for aluminum electrolytic capacitors because they are
categorized into a group of non-repairable systems, equipment
and devices for which MTTF is applicable.

Failure Rateb

Aluminum electrolytic capacitors have two categories of failures:catastrophic failure and wear-out failure.

Time

Fig-17 Bathtub curve
Early failure period
At the comparatively early periods of use, devices/components fail by deficiencies
in design or manufacturing process or incompatibility with operation conditions.
For aluminum electrolytic capacitors, these defectives are removed by debugging
at one of manufacturing processes before shipments.
b Random failure period
Failure is stable low in occurrence and appears unrelated
to their served term. Aluminum electrolytic capacitors are
low in catastrophic failures in this period compared withsemi-conductors and solid tantalum capacitors.
c Wear-out failure period
In this period, the failure rate increases with the served time.
For aluminum electrolytic capacitors, since they were completed in manufacturing, the electrolyte impregnated has gradually evaporated and diffusedout of the capacitors through the rubber seal materials with time, whichleads to decrease in the capacitance and/or increase tanδ. When any ofthese values changes beyond the allowable range of specifications, thecapacitors are defined as “fell into the wear-out failure”. The served term
until the capacitors fall into the wear-out failure period is called a useful life.
a４．Failure Modes

Failure modes depend on the application conditions that lead to fail. (Fig. 18).
Primary Factors
Failure Modes

Internal Causes

Short Circuit
1
1
Open Circuit

Short Circuit
Between Electrodes
Dielectrical Break of
Oxide Layer
Dielectrical Break of
Separator
Disconnection ofTerminal Construction
Poor Terminal
Connection

Less Electrolyte
Capacitance
Drop

3Open Vent/
Rubber Bulging

Intemal Pressure Rise

Electrolyte Leakage

Airtightness Decline

Burred Foil/
Metal Particle
Local Deficiency inOxide Layer

3
Mechanical Stress
Poor Connection

2

Deterioration With Time

1

Deterioration of
Oxide Layer
Corrosion

Unavoidable Factors
in Normal Service

2

Cathode Foil
Capacitance Drop
2

4

Mishandled
Application

Mechanical Stress2

Anode Foil
Capacitance Droptanδ（ESR）
Increase

Leakage Current
Increase

4

1Electrochemical Reaction

1

Mismanaged
Production

3
3

Excessive
Thermal Stress
Excessive
Operating Voltage
Reverse Voltage
Excessive
Ripple Current

Penetration of
Halogen Ion

Excessive
Charge-Discharge Duty
Penetration of Halogen Ion
Due To Board Cleaning

Poor Sealing

Fig-18 Failure Modes
Product specifications in this catalog are subject to change without notice.Request our product specifications before purchase and/or use. Please use our products based on the information contained in this catalog and product specifications.

CAT. No. E1001Y 2024

TECHNICAL NOTE

５．Lifetime of Aluminum Electrolytic Capacitors

5-1 Ambient Temperature Effect on Lifetime
The lifetime of aluminum electrolytic capacitors is affected mainlyby the loss of electrolyte as the result of diffusion through therubber seal materials, which leads to a decrease in capacitanceand increase in tanδ.
The relationship of temperature to the diffusion of electrolyte
follows the Arrhenius’ Law (Equations (4) and (5)):
k＝Ae

-E
RT

For lifetime estimation at a lower-temperature range, evaluation
test data have not been obtained, and for evaluating long term
endurance, it is necessary to take into account some additional
factors such as deterioration of the rubber seal materials as wellas the diffusion of electrolyte. Accordingly, in Equation (8), Tx
should be 40°C at the lowest for the lifetime calculation purpose,and also the estimated lifetime (Lx) should be 15 years at thelongest.
1,000,000

Law of 10 2 times
Law of Arrhenius
100,000

10,000Life time (hours)

The lifetime of aluminum electrolytic capacitors is largely dependent on the application conditions. Environmental factors include
temperature, humidity, atmospheric pressure and vibrations. Electrical factors include operating voltage, ripple current and chargedischarge. Where the capacitors are used in a normal filtering
circuit, ambient temperature and heating due to the ripple current
are crucial factors for determining the lifetime of the capacitors.
These factors are included to the lifetime specifications titled “Endurance” on the catalogs or product specifications.
For applications subject to high humidity and/or continuous vibrations, or subject to frequent charge and discharge operations, theendurance of individual conditions should be considered.

1,000…………………（4）（ RT ）＋ln A ………（5）-E

Applying Equation (5) to the lifetime of the capacitors brings
Equation (6), which is converted to Equation (7):E
（ LoLx ）＝2.303R（ Tx1 － To1 ）……………（6）1E
log Lx＝（ Tx － To1 ）＋log Lo ……（7）2.303Rlog

Practical estimation of the lifetime has been using Equation (8)as an approximation:
Lx ＝ Lo・Bt(To-Tx)/10……………（8）Lo：Specified lifetime (hour) with the rated voltage applied(or the rated ripple current superimposed to a DC voltage)at the upper limit of the category temperature. Refer to thelifetime specifications of individual products.
Lx：Estimated life on actual usage (hour)
To：Maximum Category Temperature（℃）
Tx：Actual Ambient Temperature（℃）
Bt ：Temperature acceleration factor
Where, the temperature acceleration factor (BT) is approximately
2 over an ambient temperature range from 60°C to 95°C, whichmeans that the lifetime is approximately halved for every 10°C risein ambient temperature. However, according to the Arrhenius
Equation (6), the reciprocal of T is directly proportional to the logarithm of lifetime, which means that, strictly speaking, there is thetemperature range where the theory of lifetime reducing by half at
every 10°C rise is not applied. (Fig. 19).
Especially for capacitors whose maximum operating temperature
is a 105°C or higher, the temperature acceleration factor (BT)needs to be modified depending on temperature ranges of the
lifetime estimation.
For details, please consult us.

10
2.3

2.4

2.5

2.6

2.7

2.8

2.9

3.0

3.1

1／T（K -1）

3.2

×10 -3

Fig-19 Estimated result by Law of 10℃ 2 times and Law of Arrhenius

5-2

Applying Voltage Effect on Lifetime

Where a capacitor is used at lower than the rated voltage, thelifetime may not be adversely affected, which means that the effectof the applying voltage is negligibly small, while the effect of theambient temperature and heat generation due to ripple current issignificant.
（Fig-20）（％）
0Capacitance Change

k ：Reaction rate constant
A：Frequency factor
E：Activation energy
R：Gas constant (8.31J/deg)
T：Absolute temperature (K)

100

－10

100V
80V
65V
50V
35V

－20
－30
－40
10

tan δ

ln k＝

100V
80V
65V
50V
35V

1
0.1
0.01

0

100

200

500

1,000

Test Hours

2,000

5,000 10,000（hours）

Fig-20 Endurance (measured by each apply voltage, result curves are overlapped)
Note: Due to the very small effect of the applying voltages, the plotscannot be distinguished from one another.

However, for capacitors of larger size and higher rated voltage
contain a larger volume of electrolyte, difference in applying
voltages can affect degradation of the oxide layer, other thanthe diffusion of electrolyte.
Therefore, for screw mount terminal type capacitors with the
rated voltage of 350Vdc or higher, the lifetime estimation
includes the effect of applying a lower voltage than the rated
voltage (derating voltage).

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CAT. No. E1001Y 2024

TECHNICAL NOTE
5-3

Ripple Current Effect on Lifetime

Since an aluminum electrolytic capacitor has a larger tanδ than other types ofcapacitors, the capacitor produces more internal heat when a ripple current flows
through it. The temperature rise due to this heat may significantly affect the lifetime of
the capacitor. This is the reason why ripple current ratings are specified for capacitors.

5-3-1

Heat Generation due to Ripple Current

Power consumption by the ripple current can be expressed as follows:
W ＝ IR2R ＋ VIL …………………………………………（9）W：Internal power dissipation
IR ：Ripple Current
R ：Internal Resistance (Equivalent Series Resistance)
V ：Applied voltage
IL ：Leakage Current
Leakage current IL at the maximum operating temperature can be 5 to 10 times higher than the valuesmeasured at 20°C. However, considering IR >> IL, the above equation can be simplified as Equation (10).
W ≒ IR2R ………………………………………………（10）To obtain the temperature at which equilibrium is achieved
between heat generation and dissipation, derive Equation (11).
IR2R ＝βAΔT …………………………………………（11）β ：Radiation Constant
A ：Surface area of can case（m2）ΔT：Temperature-rise due to the Ripple Current（℃）π
A ＝ D（D ＋ 4L）
4
D：Can Diameter (m)L：Can Length (m)From the above equation, the internal temperature rise (ΔT) is given by Equation (12):IR2R ……………………………………………
（12）
ΔT ＝
βA
Also, for a ripple frequency of 120Hz, Equation (12) for calculating
ΔT is rewritten as Equation (13):
IR2R IR2tanδ ……………………………………
＝（13）
βA βAωCtanδ
Where R ＝
ωCtanδ ：Dissipation Factor at 120Hzω：2πf（f = 120Hz）
C：Capacitance at 120Hz（F）
An approximate value of ripple current-caused ΔT can be calculated using Equation (14):ΔT ＝（Ix/Io）2 ×ΔTo ……………………………………（14）ΔT ＝

Io ：Rated ripple current (Arms), frequency compensated,
at the upper limit of the category temperature range
Ix ：Operating ripple current (Arms) actually flowing in the capacitor
ΔTo：Rise in internal temperature due to the rated ripple current (℃):
different for each product series. Please consult us.
There are some product families that can accept a higher ripple current than the rated value providingthat ambient temperature Tx is lower than the upper limit of the category temperature range. However,in this case, remember that the lifetime decreases due to the higher ΔT due to the ripple current. Be
sure that ΔT does not exceed the specified limit that has been determined as a function of ambient
temperature. Note that the core temperature limit of the element is shown by [Tx + ΔT limit].
Examples of ΔT limits at some ambient temperatures are shown below.
Ambient Temp Tx 85℃ less or equal
Limit value of ΔT
15℃

105℃
5℃

Each product family has a different ΔT limit. For details, consult us.

5-3-2

Ripple Current and Frequency

The ripple current rating is specified normally by the effective value (r.m.s value) of
120Hz or 100kHz sine wave. However, since the equivalent series resistance(ESR) of a capacitor is frequency-dependent, the allowable ripple current
depends on the frequency. Where the operating ripple current consists of a mains
power frequency element and switching frequency element(s) like switching mode
power supplies do, the internal power loss is expressed by Equation (15):W ＝ If12 Rf1 ＋ If22 Rf2 ＋……Ifn2 Rfn ……………………（15）
W：Power consumption
If1、If2、…Ifn：Ripple current (Arms) at frequency f1···fn
Rf1、Rf2、…Rfn：ESR (Ω) at f1···fn
Given a frequency compensation factor (Frequency Multiplier) = Ffn andreference frequency for the ripple current = fo, Rfn ＝ Rfo/Ffn2 is obtained.
Therefore, the ripple current at any frequency can be converted into its
r.m.s. value at the reference frequency (Ifo) using Equation (16):
Ifo= (If1/Ff1)2+(If2/Ff2)2+……(Ifn/Ffn)2 ………………………（16）
Ifo ：Reference ripple current (Arms), i.e., that at the reference frequency
Ff1、Ff2、…Ffn：Frequency compensation factor (Frequency Multiplier)at frequency f1···fn (Refer to the catalogs)
Note that the ESR depends on the temperature and the value of βdepends
on the installation conditions of the capacitor on the board. To determine moreaccurate values of ΔT, they can be actually measured using a thermocouple.

5-3-3

Lifetime Estimation

Equations (17) through (19) can be used for estimating the lifetime of a non-solid aluminum electrolytic capacitor based on the ambient temperature, therise of internal temperature due to ripple current, and operating voltage applied.
For a surface mount type or radial lead type capacitor :Endurance specifications are defined by the rated voltage.
To-Tx

-ΔT

Lx=Lo×2 10 × 2 5………………………………（17）For a surface mount type or radial lead type capacitor : Endurance
specifications are defined by “the rated ripple current superimposition”.
To-Tx

ΔTo -ΔT

Lx=Lr×2 10 × 2 5……………………………（18）For a snap-in type or screw terminal type capacitor
Kt(To-Tx)
ΔTo -ΔT
Lx=Lr×2 10 × 2 A ×Kv ……………………（19）Lo: Specified lifetime (hour) at the upper limit of thecategory temperature range and at the rated voltage
Lr: Specified lifetime (hour) at the upper limit of thecategory temperature range and at the rated
ripple current superimposed to a DC voltage
Lx: Estimation of actual lifetime (hour)To: Upper limit of the category temperature range (℃)
Tx: Actual ambient temperature of the capacitor (℃)
Use 40℃ if the actual ambient temperature is below it.
ΔT : Rise of internal temperature due to actual ripple current (℃)*ΔTo : Rise of internal temperature due to the rated ripple current (℃)*Kt : Correction factor of ambient temperature acceleration factor*Kv : Derating voltage factor (a snap-in type capacitor with the
rated voltage of less than 160Vdc and a screw terminal type
capacitor with the rated voltage of less than 350Vdc :1)*A: Acceleration factor of temperature-rise due to theripple current (This factor depends on use conditions.)
For the values marked with * , consult us.
Please consult us about lifetime equations for the series of the categorytemperature 125℃ or more.
Subject series : MXB, MHS, MVH, MHL, MHB, MHJ, MHK, GPA, GVA, GXF, GXL, GPD, GVD, GQB, GXA.
Note that the calculation results above are not considered as a guaranteed value.
When designing the lifetime of a device, please select a capacitor that has an
extra margin against the device lifetime requirements. Also, where the estimation
result calculated exceeds 15 years, please consider 15 years to be a maximum.
If 15 years or more may be required as an expected lifetime, please consult us.

Product specifications in this catalog are subject to change without notice.Request our product specifications before purchase and/or use. Please use our products based on the information contained in this catalog and product specifications.

CAT. No. E1001Y 2024

TECHNICAL NOTE
5-4 Charge and Discharge Operation Effecton Lifetime

56WV－10,000μF（φ35×60ℓ）
Measurement:20℃, 120Hz
Capacitance Change(%)

Applying a voltage to an aluminum electrolytic capacitor makes theelectric charges accumulate on the anode foil dielectric. Discharging the electricity through a discharging resistance makes the electric charges move to the cathode foil and cause chemical reactions
between the cathode aluminum and electrolyte, thereby forming adielectric oxide layer.

0Special－10－20(Vent Operated)－30

Test Conditions
Products
Applied Voltage: Rated Voltage
Ambient Temp: 60℃
τ: 0.01sec
General Cycle: Charge 30 sec, Discharge 30 sec｛

Products－40－50

When this charge and discharge is repeatedly operated, thechemical reactions proceed to further form the oxide layer on thecathode foil, causing the capacitance of the cathode foil to reduceand thereby reducing the capacitance of the capacitor. Moreover,the chemical reactions bring heat and gases. Depending on the
charge and discharge conditions, the internal pressure may
increase, the pressure relief vent may open or the capacitor may
have destructive failures. Consult us for using a capacitor with thefollowing applications:

0

1
2
4
6
Charge and Discharge Cycle (ten thousand cycle)8

Fig-23 Rapid charge and discharge characteristics(Effects of Frequency)
56WV－10,000μF（φ35×60ℓ）
Capacitance Change(%)

Measurement:20℃, 120Hz
0
－10
－20
－30
－40

・Frequently repeating power on/off.
・Repeating rapid charge and discharge operations at a short interval cycle.
・Repeating charge and discharge operations with a large voltage drop.

Test Conditions
τ: 0.01sec
Ambient Temp: 60℃
harge and Discharge: 10,000 times
Cycle: Charge 30 sec, Discharge 30 sec

｛

0.7WV

0.8WV

(Vent Operated)

GeneralProducts
0.9WV

WV

Applied Voltage/Rated Voltage Ratio

Fig-24 Rapid charge and discharge characteristics(Effects of Applied Voltage)
56WV－10,000μF（φ35×60ℓ）

Q ＝ CA V1

V1

Cathode Foil
CC

SpecialProducts

0Capacitance Change(%)

Anode Foil
CA

CA：Capacitance of Anode Foil
CC：Capacitance of Cathode Foil
V1 ：Voltage of Power Supply
V2 ：Applied Voltage to Cathode Foil

Applied Voltage: Rated Voltage
Applied Voltage: Rated Voltage
τ: 0.01sec
Charge and Discharge: 10,000 times
Cycle: Charge 30 sec, Discharge 30 sec

｛

－10
－20
－30
－40
－50

Fig-21 Charge Condition at Charge(Vent Operated)
20

40

60
70
(Vent Operated)

GeneralProducts

80

Fig-25 Rapid charge and discharge characteristics(Effects of Ambient Temperature)

Charge Transfer

V2
Anode Foil

V2
Cathode Foil

Fig-22 Charge Condition at Discharge(Disconnect V1 and Discharged condition)
Q＝CAV2＋CCV2
then
CAV1＝CAV2＋CCV2
CAV1V2＝…………………………………………（20）
CA＋CC
Figures 23 through 25 show some test data of special-design capacitors for charge and discharge application, compared with general-purpose capacitors.

5-5

Inrush Current

For the power supply inrush current that can occur on the start-up
of a power supply or on the charge of a welding machine lasts
only milliseconds, but its magnitude may reach 10 to 1,000 times
more than the normal current. Usually, a single, non-repeatedinrush current produces a negligibly small amount of heat, so it
does not matter.
However, frequently repeating inrush currents may heat up theelement inside a capacitor more than the allowable limit and/or
overheat the external terminal connections or the connections
between the internal lead and foil electrode.

Product specifications in this catalog are subject to change without notice.Request our product specifications before purchase and/or use. Please use our products based on the information contained in this catalog and product specifications.

CAT. No. E1001Y 2024

TECHNICAL NOTE
5-6

Abnormal Voltage Effect on Lifetime

Applying abnormal voltage can increase the internal pressure
with heat and gases produced, causing the pressure relief ventto open or the capacitor to have destructive failures.

5-6-1

Overvoltage

Applying a voltage higher than the rated voltage will cause
chemical reactions (formation of dielectric) to occur on the anodefoil with the leakage current rapidly increasing, which produces
heat and gases and thereby increases the internal pressure.
The reactions are accelerated by the voltage, current density
and ambient temperature, causing the pressure relief vent toopen or the capacitor to have destructive failures. It may also
accompany a reduction in capacitance and an increase in tanδas well as an increase in the leakage current, which can lead tointernal short-circuiting failure. An example of capacitor overvoltage characteristics is shown in Fig. 26.

5-6-2

Reverse Voltage

Applying a reverse voltage will cause chemical reactions (formationof dielectric) to occur on the cathode foil, and, as is the case withovervoltage, the leakage current will rapidly increase with heat andgases generating and thus the internal pressure increases.
The reactions are accelerated by the voltage, current density
and ambient temperature. It may also accompany a reduction incapacitance and an increase in tanδ as well as an increase in
the leakage current. An example of capacitor reverse-voltage
characteristics is shown in Fig. 27.
A reverse voltage of as small as 1V can cause the capacitance todecrease. A reverse voltage of 2 to 3V can shorten lifetime due toa reduction in capacitance, increase in tanδ, and/or increase inleakage current. A reverse voltage of even higher value can open
the pressure relief vent or lead to destructive failures (Fig. 27).
Ex. Radial Lead Type 25V47µF

Ex. Radial Lead Type 35V560µF
10

WV
WVx1.07
WVx1.140Capacitance Change(%)

Capacitance Change(%)

10

-10
-20
-30

WV
-1V
-3V

0
-10
-20
-30
-40

-40

1

1

0.1

tanδ

tanδ

WV
WVx1.07
WVx1.14

1000

1000
WV
WVx1.07
WVx1.14

100

Leakage Current(µA)

Leakage Current(µA)

WV
-1V
-3V

0.01

0.01

10

1

0.1

0

1000

2000

3000

4000

Time(hours)

Fig-26 Applied overvoltage characteristic at 105℃

100

10

1

5000

WV
-1V
-3V

0

250

500

750

1000

Time(hours)

Fig-27 Applied Reverse voltage characteristic at 105℃

5-6-3

Do not Use Aluminum Electrolytic Capacitorsin an AC Circuit

Using an aluminum electrolytic capacitor in an AC circuit will resultin the same situation as that with a positive potential being applied
to the cathode (like a reverse voltage) and with an excessively
large ripple current flowing in the capacitor, which may increase theinternal pressure due to the generation of heat and gases, open
the pressure relief vent, leak the electrolyte with the rubber sealbung expelled or cause the capacitor to blow up or catch fire in theworst case. If the capacitor blows up, it may scatter flammablematerials such as electrolyte and element-supporting wax materials, which can lead to short-circuiting of the device. Therefore, do
not use aluminum electrolytic capacitors in any of the AC circuits.
Product specifications in this catalog are subject to change without notice.Request our product specifications before purchase and/or use. Please use our products based on the information contained in this catalog and product specifications.

CAT. No. E1001Y 2024

TECHNICAL NOTE

6.Effect of Halogens
Aluminum electrolytic capacitors are sensitive to contaminationof halogen ions (especially to chlorine and bromine ions)though the degree of the effect depends on the properties ofthe electrolyte and/or sealing materials used in the capacitors.
For using a halide-containing flux, solvent (cleaning agent, adhesive or coating materials) or fumigant, the halide may penetrate into the capacitor through the rubber seal materials andcause the following corrosion reactions to occur. These reactions can lead to an increase in leakage current, opening of thepressure relief vent, and/or open-circuit failure in the capacitor.
The reactions are accelerated as the voltage and/or temperature rises.
[Corrosion reactions]a) Decomposition of halides+
RX + H2O → ROH + H + X …………………………… (21)b) Corrosion reactions+
AI2O3 + 6H + 6X → 2AIX3 + 3H2O …………………… (22)AI + 3X → AIX3 + 3e …………………………………… (23)

⇒

+

-

2AIX3 + 6H2O → 2AI(OH)3 + 6H + 6X ………………… (24)
RX：Halogenated compound
X-：Halogen ions（Cl , F , Br ）Halides that penetrated the element inside a capacitor makecontact with the electrolyte, by which the halides are hydrolyzed and release halogen ions as shown on Reaction (21). The
halogen ions then attack aluminum by anodic half-cell reaction,
producing AlX3 (Reaction 22 and 23).
AlX3 is then hydrolyzed, which is decomposed to aluminum hydroxide and the halogen ions (Reaction (24)). The halogen ionsreproduced are repeatedly used and reproduced by the reactions of (22) 〜 (24), and then the corrosion develops
endlessly.
Shown below are precautions for use of flux, cleaning agents,
adhesive, coating materials and fumigant.

6-1 Effect of Flux
Usually flux products contain an activator of ionic halide system, which has been associated with the corrosion issues ofcapacitors, and nowadays non-ionic halide system type flux
products have been increasingly available on the market. Someof the latter flux type have been classified into the so called
non-halogen flux or halogen-free flux , and parts of the
non-halogen or halogen-free flux products may contain alarge amount of non-ionic halides, which can also adversely affect the capacitors.

6-2 Cleaning Agents
Where cleaning the solvent resistance type of aluminum electrolytic capacitors, confirm the following conditions:a. Control the contamination (the conductivity, pH, specificgravity, water content, etc.) of the cleaning agents.
b. After the cleaning, do not leave the capacitors (assemblyboards) in an environment of cleaning agent-rich or in aclosed container. Sufficiently evaporate the residual cleaning
agent from the assembly boards and the capacitors byforced hot air at temperatures less than the upper limit of category temperature range for more than 10 minutes.
In general, aluminum electrolytic capacitors are sensitive tocontamination of halogen ions (particularly to chlorine ions).
Depending on the properties of the electrolyte and rubber
seal materials used in a capacitor, the halogen ions lead up
to catastrophic failures on the capacitor. Where the inside ofa capacitor has been contaminated with more than a certain
amount of halogen ions and the capacitor is in use, the corrosion reaction of aluminum occurs. The corrosion causes
the capacitor to have a significant increase in leakage cur-rent with heat produced, open the pressure relief vent andbecome open circuit mode failure.
Due to global environmental issues (greenhouse effects andother environmental destruction by depletion of the ozone
layer), the conventional cleaning solvents of CFC 113,
Trichloroethylene and 1,1,1-trichloroethylene were replacedby substitutes.

6-2-1 Alcohol Cleaning Agents①Fatty-alcohol cleaning agents (New type of solvent)
Pine Alpha ST-100S (Arakawa Chemical)
Clean Through 750H, 750HS and 750J (Kao)② IPA (Isopropyl alcohol)[Compatible capacitor products]
Terminal Shape

Subject Series

Surface Mount Type All Series

Radial Lead TypeAll Series

Snap-in TypeAll Series (Less and equal 100Vdc)[Cleaning conditions]
Either of Immersion or ultrasonic cleaning, for a maximum of 10
minutes at a maximum liquid temperature of 60°
C.
[Precautions]a. Make sure that the markings on a capacitor are not rubbed
against any other component or the PC board during cleaning. Note that shower cleaning can cause the markings on
the capacitor to be washed off.
b. Depending on the cleaning method, the markings may beerased or blur.
c. A drying process following a water cleaning or rinsing process may cause the outer sleeve materials of a capacitor toswell or shrink.
d. After using a weak-alkaline cleaning agent (e.g. Clean
Through 750HS, 750J), rinse with water to make sure that no
alkaline residue is left on the capacitor.
e. Control a flux concentration in a cleaning agent within 2 wt%.
f. IPS (Isopropyl Alcohol), if containing xylene or other solvent
to improve its cleanability, may swell the rubber sealmaterials.
g. Depending on the type of cleaning agent or conditions, notethat the outer sleeve of a capacitor may lose a gloss or whiten in appearance.

6-2-2 HCFC (Freon-225), as Alternative CFCs

AK225AES (Asahi Glass)[Cleaning conditions]
Solvent resistant type capacitors, which were originally developed to intend to resist Freon TE or Freon TES, are also capable of withstanding either of immersion or ultrasonic cleaning,
for a maximum of 5 minutes (or 2 minutes for KRE series or 3
minutes for SRM series). However, in view of global environmental issues, HCFCs has not been recommended.
[Compatible capacitor products]
Terminal Shape Subject Series
Surface
Mount
Type

MVE(〜63Vdc), MZS, MZL, MZR, MZJ, MZA, MVY(6.3 〜 63Vdc), MZF,
MZE ,MZK, MLA, MLF, MLE, MLK, MVL, MVJ, MHS,
MVH(〜50Vdc), MHL, MHB, MHJ, MXB, MHK

RadialLead
Type

SRG, KRG, KMQ(〜100Vdc),
LZA, LXZ, LXY, LXV, LE, GPA, GVA, GXF,
GXL, GPD, GVD, GQB, LBV, LBG

When a capacitor is mounted closely flush on the PC board, a
residual cleaning agent may be left in the gap between the
body of the capacitor and PC board surface. Dry out the residue with a forced hot air of 50 to 85°C for 10 minutes or more.

Product specifications in this catalog are subject to change without notice.Request our product specifications before purchase and/or use. Please use our products based on the information contained in this catalog and product specifications.

CAT. No. E1001Y 2024

TECHNICAL NOTE

To avoid capacitor failures, do not use the following cleaning
agents:・Halogenated system: causes capacitor failures due tocorrosion.
・Alkali system: corrodes (dissolves) the aluminum cancase.
・Terpene and petroleum system: deteriorates the rubber
seal materials.
・Xylene and toluene: deteriorates the rubber seal materials
as well.
・Acetone: erases the markings printed on a capacitor.

6-3 Adhesive and Coating Materials
To use adhesives and/or coating materials for aluminum electrolytic capacitors, make sure of the following conditions:a. Do not use any of adhesive or coating materials containing
halogenated solvents.
b. No flux residue nor stain is left between the rubber seal of acapacitor and PC board.
c. Dry the capacitor to remove residual cleaning agents before
applying adhesive and coating materials. Do not cover up theentire surface of the rubber seal of the capacitor with adhesive and coating materials.
d. Improper heating and/or curing conditions for adhesives andcoating materials may cause the sleeve to swell or shrink.
Please consult us for proper conditions.
e. For a non-solid aluminum electrolytic capacitor, covering up

7. Recovery Voltage
Where a capacitor is once charged and discharged with both of
the terminals short-circuiting and then left the terminals open
for a while, a voltage across the capacitor spontaneously increases again. This is called recovery voltage phenomenon .
The mechanism for this phenomenon can be interpreted asfollows:
When charged with a voltage, the dielectric produces someelectrical changes within, and then the inside of the dielectric iselectrified with the opposite polarities (dielectric polarization).
The dielectric polarization occurs in both ways of proceeding
rapidly and slowly. When a charged capacitor was discharged
until the voltage across the capacitor disappears, and then being left the terminals open, the slow polarization will discharge
within the capacitor and appear as recovery voltage.
(Fig. 28).
The recovery voltage changes with time as sown in Fig. 29. Its
peak will appear 10 to 20 days after the terminals are opened,with gradual weakening thereafter. Larger sized capacitors(screw terminal type and snap-in type) may produce larger recovery voltage.
With a recovery voltage residing in a capacitor, carelessly
short-circuiting the terminals can cause sparks to occur, which
may scare workers and/or damage low-voltage operating components such as CPU s and memories in the device circuit. To
avoid this trouble, discharge the capacitor through 100 - 1kΩ
resistors before use. Also, Nippon Chemi-Con may provide
some solutions with some packaging method for it. Please consult us.

the entire surface of the rubber seal with resin mold materials will obstruct the normal diffusion of internal hydrogen gas
from the capacitor and result in serious failures. Also, where
the adhesive and coating materials contain a large amountof halogen ions, the halogen ions will contaminate the insideof the capacitor through the rubber seal materials, whichcause the capacitor to become a failure.
f. The outer sleeve of a capacitor may lose a gloss or whiten inappearance depending on solvent materials that the adhesive or coating materials contains.
g. Some adhesives or coating materials contain organic solvent
such as Xylene. Xylene can deteriorate the rubber seal materials, which cause the flux ingredients to penetrate into thecapacitor.

6-4 Effect of Fumigation
In exporting or importing electronic devices, they may be exposed to fumigation with halide such as methyl bromide. Where
aluminum electrolytic capacitors exposed to halide such as methyl bromide, the capacitors will be damaged with the corrosion
reaction with the halogen ions.
For the export and import, Nippon Chemi-Con considers using
some packaging method and so forth that the fumigation is not
required to. For customers to export or import electronic devices, semi-assembly products or capacitor components, confirm
if they will be exposed to fumigation and also consider final
condition of packaging. (Note that either cardboard or vinyl
package has a risk of fumigation gas penetration.)Fig-28 Model of Recovery Voltage
Applied Voltage
The Fast Polarization

Discharge
After discharge, the electrodepotential is 0V level.

The Slow Polarization

OpenCircuits Un-polarization potential at applied voltage,
polarization will be happen gradually.

Depolarization

Residual Polarization

10
9
Recovery Voltage (V)

6-2-3 Other Solvents

8
7
6
5
4
3
2
Ex. 200V680µF(φ30×50L)

1
0
0

5

10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90
Time (day)Fig-29 Change of Recovery Voltage
Product specifications in this catalog are subject to change without notice.Request our product specifications before purchase and/or use. Please use our products based on the information contained in this catalog and product specifications.

CAT. No. E1001Y 2024

TECHNICAL NOTE

8. Storage

Capacitors that have been stored for long periods of timeshould be subjected to a voltage treatment process (see Note1) which will reform the dielectric (AI2 O 3 ) by electrolyte andreturn the leakage current to the initial level. Leakage current
increase during storage will vary with the withstanding voltage
of a capacitor. In general, the higher the rated voltage, thelarger increased the leakage current tends to be. Also, sincestoring for long period of time may shorten the lifetime of thecapacitors, consider storage conditions according to therequirements of device life expectancy.

Capacitance Change (%)

40℃
－10
70℃
－20
－30

tanδ
Leakage Current

1

70℃

100

70℃
40℃ 10

0.1

Leakage Current (µA)

Leaving them exposed to high temperatures (higher than thenormal ambient temperature) for long periods of time may leadto chemical reactions between the anode oxide layer and electrolyte, which drop the withstanding voltage and increase leakage current. If this is the case, applying the rated voltage to thecapacitor will lead to dielectric breakdown due to the heat produced with the large leakage current, which finally causes thepressure relief vent to open.

0

－40

tanδ

Some characteristics of an aluminum electrolytic capacitor are
temperature-dependent. The higher the temperature is, themore deteriorated the capacitor will be. An increase in temperature accelerates the increase in leakage current and tanδand the decrease in capacitance. Leaving a capacitor exposed
to high humidity for long hours may lead to discoloration of thelead wires and terminals, and poor solderability. To store aluminum electrolytic capacitors, keep them at normal temperatureand humidity without exposure to direct sunlight.

50WV 100µF（φ12.5×20 ）

＋10

40℃

0.01

0

1

2

1

Time (year)

Fig-30 Temperature Characteristics of Storage(Note 1) In the voltage treatment process, connecting resistor(around 1kΩ) in series with the capacitor, applied the rated
voltage and then be kept the rated voltage for 30 to 60 minutes.

Product specifications in this catalog are subject to change without notice.Request our product specifications before purchase and/or use. Please use our products based on the information contained in this catalog and product specifications.

CAT. No. E1001Y 2024

TECHNICAL NOTE

9. Tips for Selecting Capacitors Appropriate for Individual Applications
Aluminum electrolytic capacitors are used mainly for the filtering application of power supplies. Select appropriate capacitors
for the specific requirements of each application, referring to
the following examples for typical applications:

9-1 Input Filtering Capacitors for Switching Mode Power Supplies
An input filtering capacitor functions to smooth 50-120 Hz
waveforms that come from a rectifying circuit, the waveforms ofwhich are superimposed with the ripples with the switchingfrequency from the switching stage where the capacitor supplies the electric power. Therefore, the capacitor must be
capable of managing both ripple currents with each frequency.
The ESR of a capacitor is frequency-dependent, so that aripple current of different frequency produces a different thermal energy in the capacitor.
For PFC power supplies or lighting ballasts, capacitors are
subjected to ripple current whose frequency is several dozens
of kHz to 100kHz. Therefore, to select capacitors, take their
impedance characteristics into consideration.
●Representative output ﬁltering capacitors for SMPS
85℃
Characteristics
Type
Standard Longer Life Standard
Radial Lead－－
KMQ
Snap-in
SMQ
SMM
KMQ

105℃
Compact Longer Life
PAG
KXJ
KMS,KMR LXS,LXM

9-2 Output Filtering Capacitors for Switching Mode Power Supplies

For the filtering circuit for 400Vac line, two capacitors of eacha rated voltage 350 to 400Vdc can be used with being connected in series. In the series connection, voltages across theindividual capacitors during charging depend on their individual capacitance values. After completion of the charging,the voltages come to depend on their leakage current values
as the voltage distribution to the individual capacitors inversely
corresponds to their leakage current values. For the voltage
not to exceed the rated value after the charging is completed,balancing resistors should be connected in parallel with eachcapacitor. For guidance on choosing balancing resistors,
please consult us.
Where capacitors connected in series are frequently charged
and discharged, individual charging voltages depend on thevariations in their capacitance values. Therefore, keeping thevoltage balance will be difficult even if balancing resistors are
employed. For servo amplifiers and other application wherethe voltage fluctuates frequently due to regeneration, use
capacitor families that have been especially designed forintensive charge and discharge operations, or consult us forindividual designs.
●Representative ﬁltering capacitors for inverter main circuits
85℃
105℃
Characteristics
Type
Standard Longer Life Standard Longer Life
Snap-in
SMQ
SMM
KMQ
LXS,LXM
Screw Mount
RWE
RWF,RWH
KMH
LXA,LXR●Representative capacitors for servo ampliﬁers
85℃
Characteristics
Type
Standard
Snap-in－Screw Mount
RWV

105℃
High Temp
KMV－

In the output filtering, a capacitor must be capable of managing
a ripple current with the frequency as high as around 100 kHz.
Therefore, Nippon Chemi-Con provides excellent product lineups with low impedance characteristic at high frequencies,
including high temperature and long-life versions, which can bechosen according to the application purpose.
The 125˚C maximum temperature series capacitors have ashorter lifetime than the “Long Life” series of 105˚C max. temperature though the electrical characteristics are highly stable. The“wide temperature range” series has two subseries that differ by
the applicable temperature range: -55 to 105˚C and -40 to 125˚C .
The “Long Life” series capacitors have been designed for specializing lower impedance and also longer lifetime. Comparedto the “wide temperature range” series, the Long Life series canserve longer with the lower impedance, though the maximum
operating temperature is limited to 105˚C and the electricalcharacteristics are large in change over the temperature range.
●Representative output ﬁltering capacitors for SMPS
105℃
Characteristics
Type
Standard
Low Z
Wide Temp Range
LXY
LZA
Longer Life
KYB
KZN

125℃
High Temp
GPA－

9-3 Filtering Capacitors for Inverter Main
Circuits
These capacitors are used in a similar way to those for the
input of the switching mode power supplies. Additionally,please understand the following precautions:

Product specifications in this catalog are subject to change without notice.Request our product specifications before purchase and/or use. Please use our products based on the information contained in this catalog and product specifications.

CAT. No. E1001Y 2024