EPCOS B32559S

Film Capacitors
Metallized Polyester Film Capacitors (MKT)
Series/Type:
B32559S
Date:
May 2009
© EPCOS AG 2009. Reproduction, publication and dissemination of this publication, enclosures hereto and the
information contained therein without EPCOS' prior express consent is prohibited.
Metallized polyester film capacitors (MKT)
B32559S
xDSL applications, compliant with ITU-T K.45/K.20
Typical applications
Enhanced types for xDSL applications,
suitable for test conditions according to
ITU-T K.45 and ITU-T K.20.
Dimensional drawing
Climatic
Max. operating temperature: 125 °C
Climatic category (IEC 60068-1): 55/125/56
Construction
Dielectric: polyethylene terephthalate
(polyester, PET)
Stacked-film technology
Heat shrinkable tube
special xDSL types B32559S*9xx:
polyolefin 300 µm ±100 µm, 125 °C
Features
Very small dimensions
Self-healing properties
High pulse strength
Terminals
Lead spacing 5.0 mm
Crimped wire leads, lead-free tinned,
lead length (6 1) mm
Straight wire leads, lead-free tinned,
lead length (6 1) mm
Special lead length available on request
Dimensions in mm
Marking
Manufacturer's logo, rated capacitance (coded),
capacitance tolerance (code letter),
rated AC voltage, date of manufacture (coded)
Lead spacing
±0.4
5.0
Delivery mode
Bulk (untaped)
Taped (Ammo pack or reel)
For notes on taping, refer to chapter
"Taping and packing".
Detail specifications
Homologated to IEC 60384-2
Please read Cautions and warnings and
Important notes at the end of this document.
Page 2 of 18
Lead diameter d1
0.5
B32559S
xDSL applications, compliant with ITU-T K.45/K.20
Overview of available types
Lead spacing 5.0 mm
Type
B32559S
Lead
straight / crimped
configuration
Page
4
VR (V DC)
630
VRMS (V AC)
400
CR (µF)
0.0056
0.0082
0.010
0.012
0.015
0.018
0.022
0.027
Please read Cautions and warnings and
Important notes at the end of this document.
Page 3 of 18
B32559S
xDSL applications, compliant with ITU-T K.45/K.20
Ordering codes and packing units
VR
VRMS
CR
f ≤60 Hz
V DC V AC
µF
630 400
0.0056
0.0082
0.010
0.012
0.015
0.018
0.022
0.027
Max. dimensions
w×h×l
mm
4.0 × 8.5 × 7.0
4.0 × 9.0 × 7.0
4.5 × 10.0 × 7.0
4.5 × 10.0 × 7.0
4.5 × 10.0 × 7.0
5.0 × 10.0 × 7.0
5.5 × 13.0 × 7.0
6.0 × 13.5 × 7.0
Ordering code
(composition see
below)
B32559S8562+***
B32559S8822+***
B32559S8103+***
B32559S8123+***
B32559S8153+***
B32559S8183+***
B32559S8223+***
B32559S8273+***
Ammo
pack
pcs./MOQ
1600
2000
1800
1800
1800
1700
1600
1600
Reel
Untaped
pcs./MOQ
1600
1600
1500
1500
1500
1400
1400
1400
pcs./MOQ
1200
1600
1400
1400
1400
1300
1200
1200
MOQ = Minimum Order Quantity, consisting of 4 packing units.
Further E series and intermediate capacitance values on request.
B32559S8...+9xx complies with ITU-T K.45 and ITU-T K.20.
Composition of ordering code
+ = Capacitance tolerance code:
M = ±20%
K = ±10%
J = ±5%
Please read Cautions and warnings and
Important notes at the end of this document.
*** = Packaging code:
900 = Untaped crimped (lead length 6 1 mm)
902 = Untaped straight (lead length 6 1 mm)
904 = Ammo pack crimped
907 = Ammo pack straight
908 = Reel pack crimped
910 = Reel pack straight
Page 4 of 18
B32559S
xDSL applications, compliant with ITU-T K.45/K.20
Technical data
Max. operating temperature Top,max
+125 °C
Upper category temperature Tmax
+125 °C
Lower category temperature Tmin
55 °C
Rated temperature TR
+85 °C
Dissipation factor tan δ (in 10-3) at
CR ≤ 0.1 µF
at 20 °C
1 kHz 8
(upper limit values)
10 kHz 15
100 kHz 30
VR
CR ≤ 0.33 µF
Insulation resistance Rins
or time constant τ = CR Rins
≥ 250 V DC 7500 MΩ
at 20 °C, rel. humidity ≤ 65%
(minimum as-delivered values)
DC test voltage
1500 V DC, 2 s
TA (°C)
DC voltage derating
AC voltage derating
Category voltage VC
(continuous operation with VDC TA ≤ 85
VC = VR
VC,RMS = VRMS
or VAC at f ≤ 60 Hz)
85<TA≤125 VC = VR (165TA)/80 VC,RMS=VRMS (165TA)/80
TA (°C)
DC voltage (max. hours) AC voltage (max. hours)
Operating voltage Vop for
short operating periods
TA ≤ 100
Vop = 1.25 VC (2000 h) Vop = 1.0 VC,RMS (2000 h)
(VDC or VAC at f ≤ 60 Hz)
100<TA≤125 Vop = 1.25 VC (1000 h) Vop = 1.0 VC,RMS (1000 h)
Damp heat test
56 days/40 °C/93% relative humidity
Limit values after damp
Capacitance change ∆C/C
≤ 5%
heat test
Dissipation factor change ∆tan δ
≤ 5 10-3 (at 1 kHz)
Insulation resistance Rins
≥ 50% of minimum
or time constant τ = CR Rins
as-delivered values
Reliability:
Failure rate λ
1 fit (≤ 1 10-9/h) at 0.5 VR, 40 °C
Service life tSL
200 000 h at 1.0 VR, 85 °C
For conversion to other operating conditions and temperatures,
refer to chapter "Quality, 2 Reliability".
Failure criteria:
Total failure
Short circuit or open circuit
Failure due to variation
Capacitance change ∆C/C
> 10%
of parameters
Dissipation factor tan δ
> 2 upper limit value
Insulation resistance Rins
< 150 MΩ (CR ≤ 0.33 µF)
or time constant τ = CR Rins
< 50 s
(CR > 0.33 µF)
Soldering conditions
Maximum solder bath temperature
260 °C
Maximum soldering time
4s
Operating temperature range
Please read Cautions and warnings and
Important notes at the end of this document.
Page 5 of 18
B32559S
xDSL applications, compliant with ITU-T K.45/K.20
Pulse handling capability
"dV/dt" represents the maximum permissible voltage change per unit of time for non-sinusoidal
voltages, expressed in V/µs.
"k0" represents the maximum permissible pulse characteristic of the waveform applied to the
capacitor, expressed in V2/µs.
Note:
The values of dV/dt and k0 provided below must not be exceeded in order to avoid damaging the
capacitor.
dV/dt and k0 values
VR (V DC)
VRMS (V AC)
k0 in V2/µs
dV/dt in V/µs
63
40
250
30 000
100
63
300
60 000
250
160
400
200 000
400
200
600
500 000
630
400
800
1 000 000
Impedance Z versus frequency f
(typical values)
Please read Cautions and warnings and
Important notes at the end of this document.
Page 6 of 18
B32559S
xDSL applications, compliant with ITU-T K.45/K.20
Permissible AC voltage VRMS versus frequency f (for sinusoidal waveforms, TA ≤55 °C)
For TA >55 °C, please refer to "General technical information", section 3.2.3.
Lead spacing 5 mm
630 V DC/400 V AC
Permissible AC current IRMS versus frequency f
Lead spacing 5 mm
630 V DC/400 V AC
Please read Cautions and warnings and
Important notes at the end of this document.
Page 7 of 18
B32559S
xDSL applications, compliant with ITU-T K.45/K.20
Mounting guidelines
1
Soldering
1.1
Solderability of leads
The solderability of terminal leads is tested to IEC 60068-2-20, test Ta, method 1.
Before a solderability test is carried out, terminals are subjected to accelerated ageing (to
IEC 60068-2-2, test Ba: 4 h exposure to dry heat at 155 °C). Since the ageing temperature is far
higher than the upper category temperature of the capacitors, the terminal wires should be cut off
from the capacitor before the ageing procedure to prevent the solderability being impaired by the
products of any capacitor decomposition that might occur.
Solder bath temperature
235 ±5 °C
Soldering time
2.0 ±0.5 s
Immersion depth
2.0 +0/0.5 mm from capacitor body or seating plane
Evaluation criteria:
Visual inspection
Wetting of wire surface by new solder ≥90%, free-flowing solder
1.2
Resistance to soldering heat
Resistance to soldering heat is tested to IEC 60068-2-20, test Tb, method 1A.
Conditions:
Series
Solder bath temperature Soldering time
MKT boxed (except 2.5 × 6.5 × 7.2 mm) 260 ±5 °C
coated
uncoated (lead spacing > 10 mm)
MFP
MKP (lead spacing > 7.5 mm)
MKT boxed (case 2.5 × 6.5 × 7.2 mm)
MKP (lead spacing ≤ 7.5 mm)
MKT uncoated (lead spacing ≤ 10 mm)
insulated (B32559)
Please read Cautions and warnings and
Important notes at the end of this document.
Page 8 of 18
10 ±1 s
5 ±1 s
<4s
recommended soldering
profile for MKT uncoated
(lead spacing ≤ 10 mm) and
insulated (B32559)
B32559S
xDSL applications, compliant with ITU-T K.45/K.20
Immersion depth
2.0 +0/0.5 mm from capacitor body or seating plane
Shield
Heat-absorbing board, (1.5 ±0.5) mm thick, between capacitor
body and liquid solder
Evaluation criteria:
Visual inspection
∆C/C0
tan δ
Please read Cautions and warnings and
Important notes at the end of this document.
No visible damage
2% for MKT/MKP/MFP
5% for EMI suppression capacitors
As specified in sectional specification
Page 9 of 18
B32559S
xDSL applications, compliant with ITU-T K.45/K.20
1.3
General notes on soldering
Permissible heat exposure loads on film capacitors are primarily characterized by the upper category temperature Tmax. Long exposure to temperatures above this type-related temperature limit
can lead to changes in the plastic dielectric and thus change irreversibly a capacitor's electrical
characteristics. For short exposures (as in practical soldering processes) the heat load (and thus
the possible effects on a capacitor) will also depend on other factors like:
Pre-heating temperature and time
Forced cooling immediately after soldering
Terminal characteristics:
diameter, length, thermal resistance, special configurations (e.g. crimping)
Height of capacitor above solder bath
Shadowing by neighboring components
Additional heating due to heat dissipation by neighboring components
Use of solder-resist coatings
The overheating associated with some of these factors can usually be reduced by suitable countermeasures. For example, if a pre-heating step cannot be avoided, an additional or reinforced
cooling process may possibly have to be included.
EPCOS recommends the following conditions:
Pre-heating with a maximum temperature of 110 °C
Temperature inside the capacitor should not exceed the following limits:
MKP/MFP 110 °C
MKT 160 °C
When SMD components are used together with leaded ones, the leaded film capacitors should
not pass into the SMD adhesive curing oven. The leaded components should be assembled after the SMD curing step.
Leaded film capacitors are not suitable for reflow soldering.
Uncoated capacitors
For uncoated MKT capacitors with lead spacings ≤10 mm (B32560/B32561) the following measures are recommended:
pre-heating to not more than 110 °C in the preheater phase
rapid cooling after soldering
Please read Cautions and warnings and
Important notes at the end of this document.
Page 10 of 18
B32559S
xDSL applications, compliant with ITU-T K.45/K.20
2
Cleaning
To determine whether the following solvents, often used to remove flux residues and other substances, are suitable for the capacitors described, refer to the table below:
Type
Ethanol,
isopropanol,
n-propanol
MKT
(uncoated)
MKT, MKP, MFP
(coated/boxed)
Suitable
n-propanol-water
mixtures,
water with surface
tension-reducing
tensides (neutral)
Unsuitable
Solvent from
table A (see
next page)
Suitable
Suitable
Solvent from
table B (see
next page)
In part suitable Unsuitable
Even when suitable solvents are used, a reversible change of the electrical characteristics may
occur in uncoated capacitors immediately after they are washed. Thus it is always recommended
to dry the components (e.g. 4 h at 70 °C) before they are subjected to subsequent electrical testing.
Table A
Manufacturers' designations for trifluoro-trichloro-ethane-based cleaning solvents (selection)
Trifluoro-trichloroethane
Freon TF
Frigen 113 TR
Arklone P
Kaltron 113 MDR
Flugene 113
Mixtures of trifluoro-trichloro-ethane with ethanol and
isopropanol
Freon TE 35; Freon TP 35; Freon TES
Frigen 113 TR-E; Frigen 113 TR-P; Frigen TR-E 35
Arklone A; Arklone L; Arklone K
Kaltron 113 MDA; Kaltron 113 MDI; Kaltron 113 MDI 35
Flugene 113 E; Flugene 113 IPA
Manufacturer
Du Pont
Hoechst
ICI
Kali-Chemie
Rhone-Progil
Table B (worldwide banned substances)
Manufacturers' designations for unsuitable cleaning solvents (selection)
Mixtures of chlorinated hydrocarbons and ketones with fluorated hydrocarbons
Freon TMC; Freon TA; Freon TC
Arklone E
Kaltron 113 MDD; Kaltron 113 MDK
Flugene 113 CM
Please read Cautions and warnings and
Important notes at the end of this document.
Page 11 of 18
Manufacturer
Du Pont
ICI
Kali-Chemie
Rhone-Progil
B32559S
xDSL applications, compliant with ITU-T K.45/K.20
3
Embedding of capacitors in finished assemblies
In many applications, finished circuit assemblies are embedded in plastic resins. In this case,
both chemical and thermal influences of the embedding ("potting") and curing processes must be
taken into account.
Our experience has shown that the following potting materials can be recommended: non-flexible
epoxy resins with acid-anhydride hardeners; chemically inert, non-conducting fillers; maximum
curing temperature of 100 °C.
Caution:
Consult us first if you wish to embed uncoated types!
Please read Cautions and warnings and
Important notes at the end of this document.
Page 12 of 18
B32559S
xDSL applications, compliant with ITU-T K.45/K.20
Cautions and warnings
Do not exceed the upper category temperature (UCT).
Do not apply any mechanical stress to the capacitor terminals.
Avoid any compressive, tensile or flexural stress.
Do not move the capacitor after it has been soldered to the PC board.
Do not pick up the PC board by the soldered capacitor.
Do not place the capacitor on a PC board whose PTH hole spacing differs from the specified
lead spacing.
Do not exceed the specified time or temperature limits during soldering.
Avoid external energy inputs, such as fire or electricity.
Avoid overload of the capacitors.
The table below summarizes the safety instructions that must always be observed. A detailed description can be found in the relevant sections of the chapters "General technical information" and
"Mounting guidelines".
Topic
Storage conditions
Flammability
Resistance to
vibration
Safety information
Reference chapter
"General technical
information"
Make sure that capacitors are stored within the
4.5
specified range of time, temperature and humidity "Storage conditions"
conditions.
Avoid external energy, such as fire or electricity
5.3
(passive flammability), avoid overload of the
"Flammability"
capacitors (active flammability) and consider the
flammability of materials.
Do not exceed the tested ability to withstand
5.2
vibration. The capacitors are tested to
"Resistance to vibration"
IEC 60068-2-6.
EPCOS offers film capacitors specially designed
for operation under more severe vibration regimes
such as those found in automotive applications.
Consult our catalog "Film Capacitors for
Automotive Electronics".
Please read Cautions and warnings and
Important notes at the end of this document.
Page 13 of 18
B32559S
xDSL applications, compliant with ITU-T K.45/K.20
Topic
Safety information
Soldering
Do not exceed the specified time or temperature
limits during soldering.
Cleaning
Use only suitable solvents for cleaning capacitors.
Embedding of
When embedding finished circuit assemblies in
capacitors in
plastic resins, chemical and thermal influences
finished assemblies must be taken into account.
Caution: Consult us first, if you also wish to
embed other uncoated component types!
Please read Cautions and warnings and
Important notes at the end of this document.
Page 14 of 18
Reference chapter
"Mounting guidelines"
1 "Soldering"
2 "Cleaning"
3 "Embedding of
capacitors in finished
assemblies"
B32559S
xDSL applications, compliant with ITU-T K.45/K.20
Symbols and terms
Symbol
α
αC
A
βC
C
CR
∆C
∆C/C
∆C/CR
dt
∆t
∆T
∆tan δ
∆V
dV/dt
∆V/∆t
E
ESL
ESR
f
f1
f2
fr
FD
FT
i
IC
English
Heat transfer coefficient
Temperature coefficient of capacitance
Capacitor surface area
Humidity coefficient of capacitance
Capacitance
Rated capacitance
Absolute capacitance change
Relative capacitance change (relative
deviation of actual value)
Capacitance tolerance (relative deviation
from rated capacitance)
Time differential
Time interval
Absolute temperature change
(self-heating)
Absolute change of dissipation factor
Absolute voltage change
Time differential of voltage function (rate
of voltage rise)
Voltage change per time interval
Activation energy for diffusion
Self-inductance
Equivalent series resistance
Frequency
Frequency limit for reducing permissible
AC voltage due to thermal limits
German
Wärmeübergangszahl
Temperaturkoeffizient der Kapazität
Kondensatoroberfläche
Feuchtekoeffizient der Kapazität
Kapazität
Nennkapazität
Absolute Kapazitätsänderung
Relative Kapazitätsänderung (relative
Abweichung vom Ist-Wert)
Kapazitätstoleranz (relative Abweichung
vom Nennwert)
Differentielle Zeit
Zeitintervall
Absolute Temperaturänderung
(Selbsterwärmung)
Absolute Änderung des Verlustfaktors
Absolute Spannungsänderung
Differentielle Spannungsänderung
(Spannungsflankensteilheit)
Spannungsänderung pro Zeitintervall
Aktivierungsenergie zur Diffusion
Eigeninduktivität
Ersatz-Serienwiderstand
Frequenz
Grenzfrequenz für thermisch bedingte
Reduzierung der zulässigen
Wechselspannung
Frequency limit for reducing permissible Grenzfrequenz für strombedingte
AC voltage due to current limit
Reduzierung der zulässigen
Wechselspannung
Resonant frequency
Resonanzfrequenz
Thermal acceleration factor for diffusion Therm. Beschleunigungsfaktor zur
Diffusion
Derating factor
Deratingfaktor
Current (peak)
Stromspitze
Category current (max. continuous
Kategoriestrom (max. Dauerstrom)
current)
Please read Cautions and warnings and
Important notes at the end of this document.
Page 15 of 18
B32559S
xDSL applications, compliant with ITU-T K.45/K.20
Symbol
IRMS
iz
k0
LS
λ
λ0
λtest
Pdiss
Pgen
Q
ρ
R
R
Ri
Rins
RP
RS
S
t
T
τ
tan δ
tan δD
tan δP
tan δS
TA
Tmax
Tmin
tOL
Top
TR
Tref
tSL
VAC
English
(Sinusoidal) alternating current,
root-mean-square value
Capacitance drift
Pulse characteristic
Series inductance
Failure rate
Constant failure rate during useful
service life
Failure rate, determined by tests
Dissipated power
Generated power
Heat energy
Density of water vapor in air
Universal molar constant for gases
Ohmic resistance of discharge circuit
Internal resistance
Insulation resistance
Parallel resistance
Series resistance
severity (humidity test)
Time
Temperature
Time constant
Dissipation factor
Dielectric component of dissipation
factor
Parallel component of dissipation factor
Series component of dissipation factor
Ambient temperature
Upper category temperature
Lower category temperature
Operating life at operating temperature
and voltage
Operating temperature
Rated temperature
Reference temperature
Reference service life
AC voltage
Please read Cautions and warnings and
Important notes at the end of this document.
German
(Sinusförmiger) Wechselstrom
Inkonstanz der Kapazität
Impulskennwert
Serieninduktivität
Ausfallrate
Konstante Ausfallrate in der
Nutzungsphase
Experimentell ermittelte Ausfallrate
Abgegebene Verlustleistung
Erzeugte Verlustleistung
Wärmeenergie
Dichte von Wasserdampf in Luft
Allg. Molarkonstante für Gas
Ohmscher Widerstand des
Entladekreises
Innenwiderstand
Isolationswiderstand
Parallelwiderstand
Serienwiderstand
Schärfegrad (Feuchtetest)
Zeit
Temperatur
Zeitkonstante
Verlustfaktor
Dielektrischer Anteil des Verlustfaktors
Parallelanteil des Verlfustfaktors
Serienanteil des Verlustfaktors
Umgebungstemperatur
Obere Kategorietemperatur
Untere Kategorietemperatur
Betriebszeit bei Betriebstemperatur und
-spannung
Beriebstemperatur
Nenntemperatur
Referenztemperatur
Referenz-Lebensdauer
Wechselspannung
Page 16 of 18
B32559S
xDSL applications, compliant with ITU-T K.45/K.20
Symbol
VC
VC,RMS
English
Category voltage
Category AC voltage
VCD
Vch
VDC
VFB
Vi
Vo
Vop
Vp
Vpp
VR
Corona-discharge onset voltage
Charging voltage
DC voltage
Fly-back capacitor voltage
Input voltage
Output voltage
Operating voltage
Peak pulse voltage
Peak-to-peak voltage Impedance
Rated voltage
Amplitude of rated AC voltage
R
VRMS
German
Kategoriespannung
(Sinusförmige)
Kategorie-Wechselspannung
Teilentlade-Einsatzspannung
Ladespannung
Gleichspannung
Spannung (Flyback)
Eingangsspannung
Ausgangssspannung
Betriebsspannung
Impuls-Spitzenspannung
Spannungshub
Nennspannung
Amplitude der Nenn-Wechselspannung
VSC
Vsn
(Sinusoidal) alternating voltage,
root-mean-square value
S-correction voltage
Snubber capacitor voltage
Z
Impedance
Spannung bei Anwendung "S-correction"
Spannung bei Anwendung
"Beschaltung"
Scheinwiderstand
Lead spacing
Rastermaß
Please read Cautions and warnings and
Important notes at the end of this document.
(Sinusförmige) Wechselspannung
Page 17 of 18
Important notes
The following applies to all products named in this publication:
1. Some parts of this publication contain statements about the suitability of our products for
certain areas of application. These statements are based on our knowledge of typical requirements that are often placed on our products in the areas of application concerned. We
nevertheless expressly point out that such statements cannot be regarded as binding
statements about the suitability of our products for a particular customer application.
As a rule, EPCOS is either unfamiliar with individual customer applications or less familiar
with them than the customers themselves. For these reasons, it is always ultimately incumbent on the customer to check and decide whether an EPCOS product with the properties described in the product specification is suitable for use in a particular customer application.
2. We also point out that in individual cases, a malfunction of electronic components or
failure before the end of their usual service life cannot be completely ruled out in the
current state of the art, even if they are operated as specified. In customer applications
requiring a very high level of operational safety and especially in customer applications in
which the malfunction or failure of an electronic component could endanger human life or
health (e.g. in accident prevention or lifesaving systems), it must therefore be ensured by
means of suitable design of the customer application or other action taken by the customer
(e.g. installation of protective circuitry or redundancy) that no injury or damage is sustained by
third parties in the event of malfunction or failure of an electronic component.
3. The warnings, cautions and product-specific notes must be observed.
4. In order to satisfy certain technical requirements, some of the products described in this
publication may contain substances subject to restrictions in certain jurisdictions (e.g.
because they are classed as hazardous). Useful information on this will be found in our Material Data Sheets on the Internet (www.epcos.com/material). Should you have any more detailed questions, please contact our sales offices.
5. We constantly strive to improve our products. Consequently, the products described in this
publication may change from time to time. The same is true of the corresponding product
specifications. Please check therefore to what extent product descriptions and specifications
contained in this publication are still applicable before or when you place an order. We also
reserve the right to discontinue production and delivery of products. Consequently, we
cannot guarantee that all products named in this publication will always be available. The
aforementioned does not apply in the case of individual agreements deviating from the foregoing for customer-specific products.
6. Unless otherwise agreed in individual contracts, all orders are subject to the current version of the "General Terms of Delivery for Products and Services in the Electrical Industry" published by the German Electrical and Electronics Industry Association
(ZVEI).
7. The trade names EPCOS, BAOKE, Alu-X, CeraDiode, CSMP, CSSP, CTVS, DSSP,
MiniBlue, MKK, MLSC, MotorCap, PCC, PhaseCap, PhaseCube, PhaseMod, SIFERRIT,
SIFI, SIKOREL, SilverCap, SIMDAD, SIMID, SineFormer, SIOV, SIP5D, SIP5K, ThermoFuse,
WindCap are trademarks registered or pending in Europe and in other countries. Further
information will be found on the Internet at www.epcos.com/trademarks.
Page 18 of 18