Introduction

Introduction
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Vishay BCcomponents
Aluminum Capacitors
TRANSLATION OF TECHNICAL TERMS
SOME IMPORTANT TERMS
Ambient temperature (Tamb)
DES TERMES IMPORTANTES
EINIGE WICHTIGE BEGRIFFE
température ambiante
Umgebungstemperatur
Assessment level
niveau d'assurance
Gütebestätigungsstufe
Axial terminations
sorties axiales
axiale Anschlussdrähte
capacité
Kapazität
Capacitance
Charge
Climatic category
Dimensions
Discharge
Dissipation factor (tan )
Endurance
charge
laden
catégorie climatique
Klimakategorie
dimensions
Maße
décharge
entladen
tangente de l`angle de pertes
Verlustfaktor
endurance
Dauerspannungsprüfung
Equivalent series resistance (ESR)
résistance série équivalente
äquivalenter Serienwiderstand
Equivalent series inductance (ESL)
inductance série équivalente
äquivalente Serieninduktivität
taux de fiabilité
Ausfallrate
fréquence
Frequenz
usage général
allgemeine Anforderungen
impédance
Scheinwiderstand, Impedanz
sans fils
unbedrahtet
Failure rate
Frequency (f)
General purpose grade
Impedance (Z)
Leadless
Leakage current (IL)
Long life grade
Method
Mounting
courant de fuite
Reststrom
longue durée de vie
erhöhte Anforderungen
méthode
Verfahren
montage
Montage
aucun dommage
keine sichtbaren Schäden
circuit ouvert
Unterbrechung
Mounting hole diagram
dessin de montage
Bohrungsraster
Rated capacitance (CR)
capacité nominale
Nennkapazität
Rated voltage (UR)
tension nominale
Nennspannung
reprise
Nachbehandlung
tension de formation
Formierspannung
No visible damage
Open circuit
Recovery
Forming voltage (UF)
Requirements
exigences
Anforderungen
Reverse voltage (Urev)
tension inverse
Umpolspannung
Ripple current (IR)
courant ondulé
überlagerter Wechselstrom
Short circuit
Surface mounting device (SMD)
Surge voltage (US)
court-circuit
Kurzschluß
composant pour montage en surface
oberflächenmontierbares Bauelement
surtension
Spitzenspannung
Terminal pitch
distance entre les connections
Rastermaß
Terminations
sorties
Anschlüsse
durée de vie
Brauchbarkeitsdauer
examen visuel
Sichtkontrolle
Useful life
Visual examination
Revision: 17-May-16
Document Number: 28356
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Introduction
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CAPACITOR PRINCIPLES
ENERGY CONTENT OF A CAPACITOR
The essential property of a capacitor is to store electrical
charge. The amount of electrical charge (Q) in the capacitor
(C) is proportional to the applied voltage (U). 
The relationship of these parameters is:
The energy content of a capacitor is given by:
1
2
W E = --- x C x U
2
Q=CxU
Dielectric
where:
Q = charge in coulombs (C)
C = capacitance in farads (F)
U = voltage in volts (V)
Anode
Cathode
The value of capacitance is directly proportional to the
(anode) surface area and inversely proportional to the
thickness of the dielectric layer, thus:
A
A
C =  0 x  r x --d
d
εr
where:
0 = absolute permittivity (8.85 x 10-12 F/m)
C
r = relative dielectric constant (dimensionless)
A = surface area
NON-POLAR
(m2)
d = thickness of the dielectric 
(oxide layer in aluminum capacitors) (m).
Fig. 1 - Equivalent circuit of an ideal capacitor
Dielectric layer
Cathode
Anode
Electrolyte
Rins
C
Current supply
Aluminum foil
(highly etched)
RESR
LESL
Aluminum foil
POLAR
Anode electrode:
Valve effect metal: Aluminum
Al2O3
Al2O3
Electrolyte absorbing paper
(spacer)
Dielectric: Al2O3
Cathode electrode, solid or non-solid electrolyte depending on technology:
Non-solid: Wet electrolyte, spacer and aluminum foil
Solid: Solid electrolyte (e.g. manganese dioxide), graphite and silver epoxy
Fig. 2 - Equivalent circuit of an aluminum capacitor
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ELECTRICAL BEHAVIOR
Characteristics of aluminum capacitors vary with temperature, time and applied voltage.
Ripple
current
capability
C
Frequency
Frequency
Leakage
current
tan δ
Frequency
Z
Temperature
Leakage
current
Z
ESR
ESR
Load time
Frequency
C/C0
Z/Z0
Leakage
current
ESR
ESR
ESR0
25 °C
C
tan δ
ESR
Z
Voltage
Temperature
C
failure
rate
tan δ
ESR/Z
Life time
ripple
current
capability
Temperature
failure
rate
Temperature
% rated voltage
Fig. 3 - Typical variation of electrical parameters as a function of frequency, ambient temperature, voltage and time
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CONSTRUCTION
Examples
Wound cell, consisting of:
Solvent-resistant
shrink sleeves
gives high insulation
resistance
- Paper spacer
impregnated with
electrolyte
- Aluminum foil cathode
Flattened cathode lead
Flattened anode lead
Base plate
Aluminum can
Aluminum can,
fully covered with
insulating foil
- Aluminum foil anode
with aluminum oxide
dielectric
Aluminum
connection part
Rubber sealing
High-quality
low-resistance
laser weld between
connections and
anode/cathode.
This means low
ESR and ESL
Special design so that
insertion forces on the connections
do not stress the windings mechanically
Wound cell,
consisting of:
- Aluminum foil anode
with aluminum oxide
dielectric
- Paper spacer
impregnated with
electrolyte
- Aluminum foil cathode
Non-porous, teflon
coated hard paper
disc and rubber insert
for optimum seal
Snap-in connections
for fast assembly
Fig. 7 - Large aluminum, snap-in
Fig. 4 - Surface mount device (vertical style)
Aluminum can
Epoxy resin
Cone-shaped flange
Wound cell, consisting of:
Insulating sleeve
Cathode lead
- Aluminum foil anode
with aluminum oxide
dielectric
- Paper spacer impregnated
with electrolyte
- Aluminum foil cathode
Cathode connection:
Rubber sealing
Etched Aluminum
Silver epoxy on graphite covered with Al2O3 Anode lead
and manganese dioxide (dielectric)
Aluminum
connection part
Fig. 8 - Solid aluminum (SAL), radial
Anode and cathode lead,
tin plated
Terminals
Fig. 5 - Radial aluminum
Aluminum can
Cathode lead
Synthetic disc sealed
by rubber gasket
Pressure relief
Paper spacer
impregnated
with electrolyte
Multi-welded low
ESR connections
Sealing disc
Winding of high purity
etched aluminum and
electrolyte impregnated
paper spacer
Blue insulating
sleeve
Cathode tab foil
welded to the bottom
of the can
Aluminum foil anode
with aluminum oxide
dielectric
Solvent resistant
insulating sleeve
Anode lead
Aluminum
foil cathode
Fig. 6 - Axial aluminum
Revision: 17-May-16
Bolt for mounting
(optional)
Fig. 9 - Large aluminum, screw terminal
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DEFINITIONS OF ELECTRICAL PARAMETERS
VOLTAGE
Sequence of measurement for tests are in accordance with
“IEC 60384-4”:
RATED VOLTAGE (UR)
The maximum DC voltage, or peak value of pulse voltage
which may be applied continuously to a capacitor at any
temperature between the lower category temperature and
the rated temperature.
1. Leakage current (IL)
2. Capacitance (CR)
3. Dissipation factor (tan or ESR)
CATEGORY VOLTAGE (UC)
The maximum voltage which may be applied continuously to
a capacitor at its upper category temperature.
4. Impedance (Z)
CAPACITANCE
AC CAPACITANCE OF AN ALUMINUM CAPACITOR
The capacitance of an equivalent circuit, having
capacitance, resistance and inductance in series, measured
with alternating current of approximately sinusoidal
waveform at a specified frequency; refer to Fig. 10.
Standard measuring frequencies for aluminum capacitors
are 100 Hz or 120 Hz.
C
ESR
ESL
VAC
Fig. 10 - AC equivalent circuit of an aluminum capacitor
DC CAPACITANCE OF AN ALUMINUM CAPACITOR 
(FOR TIMING CIRCUITS)
TEMPERATURE DERATED VOLTAGE
The temperature derated voltage is the maximum voltage
that may be applied continuously to a capacitor, for any
temperature between the rated temperature and the upper
category temperature.
RIPPLE VOLTAGE (URPL)
An alternating voltage may be applied, provided that the
peak voltage resulting from the alternating voltage, when
superimposed on the DC voltage, does not exceed the value
of rated DC voltage or fall under 0 V and that the ripple
current is not exceeded.
REVERSE VOLTAGE (UREV)
The maximum voltage applied in the reverse polarity
direction to the capacitor terminations.
DC capacitance is given by the amount of charge which is
stored in the capacitor at the rated voltage (UR). 
DC capacitance is measured by a single discharge of the
capacitor under defined conditions. Measuring procedures
are described in “DIN 41328, sheet 4” (withdrawn).
SURGE VOLTAGE (US)
The maximum instantaneous voltage which may be applied
to the terminations of the capacitor for a specified time at
any temperature within the category temperature range.
At any given time, the DC capacitance is higher than the AC
capacitance.
TEMPERATURE
CDC
ESR
Rleak
Fig. 11 - DC equivalent circuit of an aluminum capacitor
RATED CAPACITANCE (CR)
The capacitance value for which the capacitor has been
designed and which is usually indicated upon it.
Preferred values of rated capacitance and their decimal
multiples are preferably chosen from the E3 series of
“IEC Publication 60063“.
TOLERANCE ON RATED CAPACITANCE
Preferred values of tolerances on rated capacitance:
-20 % / +20 % -10 % / +50 % -10 % / +30 % -10 % / +10 %
M
T
Q
These values depend on the relevant series.
Revision: 17-May-16
K
CATEGORY TEMPERATURE RANGE
The range of ambient temperatures for which the capacitor
has been designed to operate continuously: this is defined
by the temperature limits of the appropriate category.
RATED TEMPERATURE
The maximum ambient temperature at which the rated
voltage may be continuously applied.
MINIMUM STORAGE TEMPERATURE
The minimum permissible ambient temperature which the
capacitor shall withstand in the non-operating condition,
without damage.
RESISTANCE / REACTANCE
EQUIVALENT SERIES RESISTANCE (ESR)
The ESR of an equivalent circuit having capacitance,
inductance and resistance in series measured with
alternating current of approximately sinusoidal waveform at
a specified frequency; refer to Fig. 10.
EQUIVALENT SERIES INDUCTANCE (ESL)
The ESL of an equivalent circuit having capacitance,
resistance and inductance in series measured with
alternating current of approximately sinusoidal waveform at
a specified frequency; refer to Fig. 10.
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DISSIPATION FACTOR (TANGENT OF LOSS ANGLE; tan )
The leakage current requirements for the majority of Vishay
BCcomponents aluminum capacitors, are lower than
specified in “IEC 60384-4” or “EN130300”.
The power loss of the capacitor divided by the reactive
power of the capacitor at a sinusoidal voltage of specified
frequency. The dissipation factor can be approximated by
following formula:
If, for example, after prolonged storage and / or storage at
excessive temperature (> 40 °C), the leakage current at the
first measurement does not meet the requirements,
pre-conditioning shall be carried out in accordance with
“EN130300 subclause 4.1”.
tan  = ESR x 2fC
IMPEDANCE (Z)
LEAKAGE CURRENT AT DELIVERY (IL1 or IL2)
The impedance (Z) of an aluminum capacitor is given by
capacitance, ESR and ESL in accordance with the following
equation (see Fig. 12):
Z=
2
1
ESR +  2fESL - -------------
2fC
In addition to IL5, the leakage current after 1 min application
of rated voltage (IL1) is specified in most of the detail
specifications.
2
For some series this value is specified after 2 min (IL2).
OPERATIONAL LEAKAGE CURRENT (IOP)
CURRENT
After continuous operation (1 h or longer) the leakage
current will normally decrease to less than 20 % of the 5 min
value (IL5).
LEAKAGE CURRENT (IL)
The DC current flowing through a capacitor when a DC
voltage is applied in correct polarity. It is dependent on
voltage, temperature and time.
The operational leakage current depends on applied voltage
and ambient temperature; see Tables 1 and 2.
LEAKAGE CURRENT FOR ACCEPTANCE TEST (IL5)
LEAKAGE CURRENT AFTER STORAGE WITH NO
VOLTAGE APPLIED (SHELF LIFE)
In accordance with international standards (“IEC 60384-4”
and “EN130300”) the leakage current (IL5) after 5 min
application of rated voltage at 20 °C is considered as an
acceptance requirement.
If non-solid aluminum capacitors are stored above room
temperature for long periods of time, the oxide layer may
react with the electrolyte, causing increased leakage current
when switched on for the first time after storage.
Table 1
TYPCIAL MULTIPLIER OF OPERATIONAL LEAKAGE CURRENT AS A FUNCTION OF AMBIENT TEMPERATURE
MULTIPLIER (1)
SYMBOL
Tamb (°C)
-55
-40
-25
0
20
45
65
85
105
125
150
IOP/IL
< 0.5
0.5
0.6
0.8
1
1.5
2.5
4
7
10
15
Note
(1) As far as allowed for the corresponding series
Table 2
TYPCIAL MULTIPLIER OF OPERATIONAL LEAKAGE CURRENT AS A FUNCTION OF APPLIED VOLTAGE
SYMBOL
MULTIPLIER
U/UR
< 0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
IOP/IL
0.1
0.15
0.2
0.3
0.4
0.5
0.65
0.8
1.0
2πfESL
ESR
1
2πfC
δ
Z
Fig. 12 - Vector diagram showing the AC parameters of a capacitor
Revision: 17-May-16
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RATED RIPPLE CURRENT (IR)
Any pulsating voltage (or ripple voltage superimposed on
DC bias) across a capacitor results in an alternating current
through the capacitor.
Because of ohmic and dielectric losses in the capacitor, this
alternating current produces an increase of temperature in
the capacitor cell.
The heat generation depends on frequency and waveform of
the alternating current.
The maximum RMS value of this alternating current, which
is permitted to pass through the capacitor during its entire
specified useful life (at defined frequency and defined
ambient temperature), is called rated ripple current (IR).
The rated ripple current is specified in the relevant detail
specifications at 100 Hz or 120 Hz (in special cases at
100 kHz and at upper category temperature.
Usually the rated ripple current will cause a temperature
increase of the capacitor's surface of approximately 3 K or
5 K (dependent on series) compared with ambient
temperature. A further temperature increase of 3 K or 5 K
will be found in the core of the capacitor.
This temperature rise is the result of the balance between
heat generated by electric losses:
Vishay BCcomponents
vectorial sum of the currents thus found may not exceed the
applicable ripple current.
For some frequently occurring waveforms, approximation
formula are stated in Fig. 13 for calculating the
corresponding RMS value.
RMS VALUE
WAVE FORM
A
t0
t0
A
t
T
A
t2
t1
T
t1 + t2
A
t
3T
T
A
t2
t2
t1
2 t1 + 3 t2
t
3T
A
T
2
P = I R ESR
A
and the heat carried off by radiation, convection and
conduction:
P = T x A x 
IR can be determined by the equation:
IR =
T x A x 
---------------------------ESR
where:
T = difference of temperature between ambient and case
surface (3 K to 5 K, dependent on series)
A = geometric surface area of the capacitor
 = specific heat conductivity, dependent on the size of the
capacitor
The heat, generated by ripple current, is an important factor
of influence for non-solid aluminum capacitors for
calculating the useful life under certain circumstances.
In the detail specifications this factor is considered in the
so-called “life-time nomograms” (“Multiplier of useful life”
graph) as a ratio between actual ripple current (IA) and rated
ripple current (IR), drawn on the vertical axis.
Care should be taken to ensure that the actual ripple current
remains inside the graph at any time of the entire useful life.
If this cannot be realized, it is more appropriate to choose a
capacitor with a higher rated voltage or higher capacitance,
than originally required by the application.
The internal losses and the resultant ripple current capability
of aluminum capacitors are frequency dependent.
Therefore, a relevant frequency conversion table (“Multiplier
of ripple current as a function of frequency”) is stated in the
detail specifications. See also “CALCULATION OF USEFUL
LIFE BY MEANS OF ‘LIFE-TIME NOMOGRAMS’.”
CALCULATION OF THE APPLICABLE RMS RIPPLE
CURRENT
Non-sinusoidal ripple currents (if not accessible by direct
measurement) have to be analyzed into a number of
sinusoidal ripple currents by means of Fourier-analysis; the
Revision: 17-May-16
t0
t0
t
A
2T
T
Fig. 13 - Approximation formula for RMS values of
non-sinusoidal ripple currents
STORAGE
No pre-condition will be necessary for Vishay
BCcomponents aluminum capacitors, when stored under
standard atmospheric conditions (15 °C to 25 °C; 25 % to
75 % RH; 860 mbar to 1060 mbar) for the following periods
of time:
• 1 year for DLC and polymer types
• 2 years for ENYCAPTM
• 3 years for non-solid 85 °C types
• 4 years for non-solid 105 °C types
• 10 years for non-solid 125 °C types and 150 °C types
• 20 years for solid types
For non-solid capacitors after these periods, the leakage
current for acceptance test shall not exceed twice the
specified IL5 requirement.
A limited current can be applied to reduce the leakage
current of long stored non-solid capacitors to normal values.
The maximum allowed current when doing this at room
temperature is given by the following formula:
D 2
x
I max. = ------------- x   ---- +  D x L 
 2

Ur
In this equation, Ur is the rated voltage, D the diameter of the
capacitor can and L the length of the capacitor can. When
Imax. is in mA, D in mm and L in mm, the value for  is
1 mW/mm2. During this reforming process, the rated voltage
shall not be exceeded.The process has ended when the
current drops below the specified leakage current.
To ensure good solderability and quality of taping, for all
types and prior to mounting, the storage time shall not
exceed 3 years. This means for example: 2 years storage
time between manufacture and arrival at the customer, plus
1 year in customer storage.
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OPERATIONAL CONDITIONS
CHARGE-DISCHARGE PROOF
This term means the capability of capacitors to withstand
frequent switching operations without significant change of
capacitance.
Vishay
BCcomponents
aluminum
capacitors
are
charge-discharge proof in accordance with “IEC 60384-4”
and “EN130300 subclause 4.20”: unless otherwise
specified, 106 switching operations (RC = 0.1 s) shall not
cause a capacitance change of more than 10 %.
Non-frequent charging and discharging, without a series
resistor, will not damage the capacitor.
If a capacitor is charged and discharged continuously
several times per minute, the charge and discharge currents
have to be considered as ripple currents flowing through the
capacitor. The RMS value of these currents should be
determined and the resultant value must not exceed the
applicable limit.
ENDURANCE TEST
In “IEC 60384-4” or “EN130300” the criteria for the
acceptable drift of electrical parameters after the endurance
test at UR and upper category temperature are defined.
Test duration and conditions per series are stated in the
relevant detail specification.
The endurance test does not provide information about the
useful life of a capacitor, as no failure percentage is defined
for this test.
USEFUL LIFE
Useful life (other names: load life, life time or typical life time)
is that period of time, during which a given failure
percentage may occur, under well defined conditions and
requirements. Useful life data are usually calculated with a
confidence level of 60 %.
High quality of materials and controlled manufacturing
processes provided, the useful life of non-solid aluminum
capacitors is, in most cases, determined by evaporation of
electrolyte through the sealing.
Fig. 14 shows the principal electrical consequences of this
electrolyte loss: increasing impedance and decreasing
capacitance at the end of useful life, for different non-solid
types.
Due to the fact that no liquid electrolyte is used in solid
aluminum capacitors, the associated failure mechanism
does not occur.
For non-solid aluminum capacitors the influence of
temperature on useful life is approximated by the so-called
“10 K-rule”. The “10 K-rule” states that double the life time
can be expected per 10 K temperature decrease; this
principle is derived from the well known law of Arrhenius
about acceleration of reaction processes.
The exact temperature dependence of useful life for a
particular range is given in the corresponding detail
specification in the “life-time nomogram” (“Multiplier of
useful life” graph in the detail specifications). Detailed
performance requirements, on which the definition “useful
life” is based, are also stated in the relevant detail
specifications.
Exceeding those requirements shall not necessarily induce
a malfunction of the equipment involved. The performance
requirements offer advice on the choice of components and
design of the circuitry.
Typ. useful life
Typ. useful life
of standard types of long life types
Typ. useful life
of extra long life types
SAL-capacitors
100
ΔC0 90
C
80
%
70
60
Z/ZD
50
%
40
400
300
200
100
C0 = Initial value of capacitance
ZD = Specified limit of impedance
Standard
Long life
Extra long life
SAL-capacitors
10K-rule
2000 h/85 °C
4000 h/75 °C
8000 h/65 °C
> 5 years/40 °C
8000 h/85 °C
16 000 h/75 °C
32 000 h/65 °C
> 20 years/40 °C
30 000 h/85 °C
60 000 h/75 °C
120 000 h/65 °C
> 50 years/40 °C
Life time at specified ambient temperature
Fig. 14 - Principal trend of electrical parameters during useful life of different aluminum capacitors
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CALCULATION OF USEFUL LIFE BY MEANS OF “LIFE-TIME NOMOGRAMS”
Based on the Arrhenius law and on experience for some
decades, a nomogram is specified in the detail specification
for each range, where the influence of ambient temperature
and ripple current on the expected useful life is shown.
Ripple currents at other frequencies than specified must be
corrected using the frequency conversion tables in the
relevant detail specification.
The ratio of actual ripple current to rated ripple current (IA/IR)
is plotted on the vertical axis and the ambient temperature
(Tamb) on the horizontal.
3.6
3.5
3.4
3.3
3.2
3.1
3.0
2.8
Lifetime multiplier
2.6
2.4
5
1. 0
2.
2.2
0
3. 0
4.
2.0
0
6.
0
8.
12
The useful life determined by this procedure is valid for
applications without forced cooling. If IA/IR > 1 and
additional cooling is applied, the useful life may be
considerably extended.
IA = Actual ripple current at specified conditions
IR = Rated ripple current, multiplied with the
frequency correction factor (see relevant tables
in the detail specifications)
0
1.
At the intersection of these two operational conditions the
appropriate multiplier (correction factor) for useful life can be
read. The useful life under these operational conditions shall
be calculated by multiplying the specified useful life with the
correction factor read.
IA 3.8
IR 3.7
1.8
1.6
3.1
3.0
2.8
2
IA = Actual ripple current at specified conditions
IR = Rated ripple current, multiplied with the frequency
correction factor (see relevant tables in the
detail specifications)
1.4
1.2
1.0
0.8
0.5
0.0
60 0
10 0
15 00
IA
IR 3.2
20
30
3.3
40
50
60
70
80
90
110
100
Tamb (°C)
Fig. 16 - Typical example of a life-time nomogram as used for axial
and radial 105 °C types: useful life as a function of ambient
temperature and ripple current load
2.6
EXAMPLES FOR THE USE OF “LIFE-TIME NOMOGRAMS”
2.4
Example 1
Lifetime multiplier
2.2
0
1.
0
2.
Which useful life can be expected (without pause and
storage times):
0
3.
1.8
0
4.
1. For a capacitor with a specified useful life of 2000 h at
85 °C
0
6.
1.6
10
1.4
15
20
30
2. For a capacitor with a specified useful life of 2000 h at
105 °C
50
70
1.2
1.0
0.8
0.5
0.0
Ripple current load is exactly the rated value (thus: IA/IR = 1).
5
1.
2.0
40
Temperature in (operating) equipment is 45 °C.
Solution:
50
60
70
80
90
100
Tamb (°C)
Fig. 15 - Typical example of a life-time nomogram as used for axial
and radial 85 °C types: useful life as a function of ambient
temperature and ripple current load
the corresponding life-time multiplier may be found at the
intersection between the vertical “45 °C”-line and the
horizontal “1”-line. For the 85 °C type this is “30” (see
Fig. 15) and for the 105 °C type it is “90” (see Fig. 16).
Resulting useful life is thus:
1. For 85 °C type: 30 x 2000 h = 60 000 h or about 7 years
2. For 105 °C type: 90 x 2000 h = 180 000 h or about
20 years.
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Example 2
Example 3
Which life time requirement has to be fulfilled by the
capacitors, if the equipment life shall be 10 years (approx.
100 000 h), consisting of 1000 h at 75 °C + 9000 h at
65 °C + 90 000 h at 40 °C.
No ripple current applied (thus: IA/IR = 0).
Which internal temperature may occur in the equipment, if
the actual ripple current at 10 kHz is 3 times higher than
specified for a 16 V-type and the load limit may not be
exceeded?
Solution:
the ripple current must first be converted from 10 kHz to
100 Hz by using the conversion table (see typical example,
Table 3). This shows that the conversion factor for a
16 V-type is 1.2.
the mentioned life-times shall be converted to specified
85 °C or 105 °C life-times, i.e. they have to be divided
through the correction factors found at the intersection of
the respective operational conditions (see Table 4).
The required life-time can be fulfilled by types with a
specified useful life of:
1. > 2970 h at 85 °C i.e. a 3000 h/85 °C type, or
2. > 935 h at 105 °C i.e. a 1000 h/105 °C type.
Solution:
IA/IR = 3 at 10 kHz and must be divided by 1.2, resulting in
IA/IR = 2.5 at 100 Hz.
The load limit is defined by the diagonal line “multiplier 1” in
the relevant nomogram.
This means here: the vertical line on the intersection of
IA/IR = 2.5 and the multiplier 1-line shows the maximum
permitted internal temperature:
1. For 85 °C types this is max. 59 °C
2. For 105 °C types this is max. 79 °C
The corresponding life-time in this case is equal to the
specified useful life.
Table 3
TYPICAL EXAMPLE OF A FREQUENCY CONVERSION TABLE
FREQUENCY
(Hz)
(1)
IR MULTIPLIER
UR = 6.3 V TO 25 V
UR = 35 V AND 40 V
UR = 50 V AND 63 V
50
0.95
0.85
0.80
100
1.00
1.00
1.00
300
1.07
1.20
1.25
1000
1.12
1.30
1.40
3000
1.15
1.35
1.50
 10 000
1.20
1.40
1.60
Note
(1) (I /I ) as a function of frequency; I = rated ripple current at 100 Hz
R,f R
R
Table 4
LIFE-TIME CALCULATION in “Example 2”
LIFE CONDITIONS
85 °C TYPES (see Fig. 15)
105 °C TYPES (see Fig. 16)
1000 h at 75 °C
1000/2.9 = 345 h
1000/8 = 125 h
9000 h at 65 °C
9000/6 = 1500 h
9000/20 = 450 h
90 000 h at 40 °C
90 000/80 = 1125 h
90 000/250 = 360 h
Sum for 85 °C = 2970 h
Sum for 105 °C = 935 h
Revision: 17-May-16
Document Number: 28356
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FAILURE RATE () TOTAL FAILURE PERCENTAGE
Aluminum capacitors, like many other electronic
components and devices, exhibit a failure rate which varies
with time as depicted in the familiar “bathtub” curve (see
Fig. 17). Three distinct regions can be discerned:
a. Burn-in period, showing a rapidly decreasing failure rate.
During production of Vishay BCcomponents’ aluminum
capacitors all capacitors undergo a re-forming process
which is a short burn-in. All capacitors shipped have
passed burn-in.
b. Constant failure period, showing a low failure rate for a
long period. This is the “useful life” period of the
aluminum capacitor. The detail specifications of the
relevant series specify the upper limit for the total failure
percentage (TFP) during this period. For non-solid
aluminum capacitors this limit is usually not reached
before the wear-out period begins.
c. Wear-out period, showing an increasing failure rate due
to gradual deterioration. For aluminum capacitors with
non-solid electrolyte, the onset of this period can be
calculated with the nomogram (see Fig. 18).
The failure rate is the number of components failing within a
unit of time. For region (b), where the failure rate has a
constant value , the total failure percentage as a function of
time, TFP(t), can be expressed as:

N(t) 
- x t
TFP(t) =  1 - ----------  x 100 % =  1 - e
 x 100 %
N(0)



with
 =  40 °C, 0.5 U x mult  T U /U R 
103
Failure rate
multiplying
factor
U/UR =
102
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
10
1
10-1
0
20
40
60
80
100
120
N(t) is the number of components that have not failed after
time t. As  mainly depends on two stress factors,
temperature and the ratio of applied voltage to rated
voltage, it is common to normalize it to reference
conditions, Tamb = 40 °C and U = 0.5 x UR. The value for
 40 °C, 0.5 U is calculated from results of periodical tests in
R
the quality laboratories or derived from field observations.
Fig. 18 - Conversion factors for failure rate () as a function of
ambient temperature (Tamb) and voltage ratio (U/UR) for non-solid
aluminum capacitors
Failure rate
multiplying
factor
U/UR =
1.0
0.9
10
In order to calculate  for other operating conditions, the
value for the failure rate multiplying factor, mult (T, U/UR) in
the formula above, must be taken from Fig. 18 (non-solid
aluminum capacitors) or Fig. 19 (solid aluminum capacitors).
Factory
(a)
Customer
(b)
a) Initial failure period (“infant mortality”)
b) Random failure period (= Useful life period)
c) Wear-out failure period
0.8
0.7
0.6
0.5
0.4
0.3
0.2/0.1
1
(c)
Time (t)
Fig. 17 - Failure rate () as a function of time
(“bathtub” curve)
Revision: 17-May-16
160 180
Tamb (°C)
102
R
Failure
rate
(λ)
140
10-1
0
50
100
150
Tamb (°C)
Fig. 19 - Conversion factors for failure rate () as a function of
ambient temperature (Tamb) and voltage ratio (U/UR) for solid
aluminum capacitors
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CLIMATIC CATEGORY
For each capacitor range the climatic category in accordance with “IEC 60068-1” is stated in the relevant detail specification.
The climatic category consists of three digit groups; example given in Table 5.
Table 5
EXAMPLE OF CLIMATIC CATEGORIES
Example:
40
085
56
40
Lower category temperature (here: -40 °C)
085
Upper category temperature (here: +85 °C)
56
Duration of test “damp heat, steady state” (here: 56 days)
Table 6
MAXIMUM HUMIDITY CONDITION INDICATION FOR THE APPLICATION CLASS
RELATIVE AIR HUMIDITY
CODE
LETTER
YEARLY
AVERAGE
30 DAYS
PER YEAR
OCCASIONALLY
C
 95 %
100 %
100 %
Permitted
D
 80 %
100 %
90 %
Permitted
E
 75 %
95 %
85 %
Slightly / rarely
F
 75 %
95 %
85 %
Not permitted
DEWING
APPLICATION CLASS
DESIGN RULES FOR “CAPACITOR BATTERIES”
Although the German standard “DIN 40040” has been
withdrawn, it is still widely used in industrial specifications
for the definition of climatic working conditions. The
application class consists of 3 code letters which have the
following meanings.
MECHANICAL
CODE LETTER MEANINGS
1st letter:
Lower category temperature
F: -55 °C; G: -40 °C; H: -25 °C
2nd letter:
Upper category temperature
P: +85 °C; M: +100 (+105) °C;
K: +125 °C; H: +155 (+150) °C
3rd letter:
Maximum humidity conditions (see Table 6)
Vishay BCcomponents large aluminum capacitors are
mainly used in power supply applications under high ripple
current load. In these circumstances, the capacitors must
be mounted with a distance of  15 mm from each other, in
order to allow sufficient air circulation and to prevent mutual
radiation.
Likewise, if axial or radial types are subject to high ripple
load, they shall be mounted with sufficient distance
(e.g.  10 mm) from each other for good convection.
ELECTRICAL
Parallel connection
MOUNTING
MOUNTING POSITION OF NON-SOLID ALUMINUM
CAPACITORS
Snap-in and printed wiring (PW) as well as solder lug (SL)
aluminum capacitors, in addition to the larger case sizes of
axial and radial types, are normally equipped with pressure
relief in the aluminum case. These and all smaller case size
types, may be mounted in any position.
Screw-terminal aluminum capacitors have a pressure relief
in the sealing disc. These types shall be mounted so that no
emissions of electrolyte or vapor may reach either the
conductors under voltage, or other parts of the printed
circuit board. Vertical (pressure relief up) or horizontal
(pressure relief on the upper side) mounting position is
recommended.
Revision: 17-May-16
Aluminum capacitors may be connected in parallel, but for
safety reasons, large sizes should be individually guarded
against sudden energy discharge of the whole battery due
to a defective specimen.
Series connection
If two aluminum capacitors are connected in series,
balancing resistors are required; see Fig. 20. Without these
resistors, leakage current through both capacitors is the
same. Because the leakage current for two capacitors can
be quite different when the same voltage is applied, forcing
the same current through both capacitors will mean that the
voltage will not divide evenly. One capacitor might be
subjected to a voltage exceeding its rated voltage. Parallel
balancing resistors limit the difference in voltage across the
capacitors under DC conditions.
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For practical purposes the following equation can be used
to calculate the maximum possible resistor values in ohms:
2 x U m - U total
R = ---------------------------------------I L5
C1
R
C2
R
Utotal
Here, Um is the maximum (rated) voltage that may be
present on one of the capacitors and IL5 is the specified
leakage current in amperes after 5 min (used as an
approximation of the difference in leakage current between
C1 and C2).
Um
Fig. 20 - Balancing resistors for two aluminum capacitors in series
Combined series / parallel connection
The above mentioned rules for both series and parallel
connection are accordingly valid for any combination of
these two cases.
MARKING
Vishay BCcomponents aluminum capacitors are identified in accordance with “IEC” rules. When sufficient space is available,
capacitors are marked with the following details:
Rated capacitance
Rated voltage
in μF (the “μ” sign represents the position of the decimal point)
in V
Tolerance on rated capacitance
If necessary, as a letter code in accordance with “IEC 60062”, e.g.
T for -10 % / +50 %
M for ± 20 %
K for ± 10 %
Q for -10 % / +30 %
A for tolerance according to detail specification
Group number
Catalog number
Name of manufacturer
3-digit part of the catalog number, e.g. 036 for RSP series
or last 8-digits of the catalog number
BCcomponents or BCC or BC
Date code
Abbreviation in 2 digits (“IEC 60062”), e.g.
1st digit
X = 2009
F = 2015
A = 2010
H = 2016
B = 2011
J = 2017
C = 2012
K = 2018
D = 2013
L = 2019
E = 2014
M = 2020
2nd digit
1
= January
2
= February
...
9
= September
O or A = October
N or B = November
D or C = December
Example:
B5 = produced in 2011, May
Production date may also be stated as year / week code.
Date code may also be stamped in the case.
Factory code
Indicating the factory of origin
Polarity identification
Strip, band or negative symbol (“-” sign) to indicate the negative terminal and / or a “+” sign
to identify the positive terminal.
Revision: 17-May-16
Document Number: 28356
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