NTC thermistors for
temperature measurement
Probe assemblies
Series/Type: B57045K
Date: March 2013
© EPCOS AG 2015. Reproduction, publication and dissemination of this publication, enclosures hereto and the
information contained therein without EPCOS' prior express consent is prohibited.
EPCOS AG is a TDK Group Company.
Applications
Temperature compensation, measurement
and control (chassis mounting)
Features
Cost-effective
Good thermal coupling through screw-type
case (thread M3)
Electrically isolated aluminum case
Tinned copper leads
Options
Tighter resistance tolerance available on
request.
Delivery mode
Bulk
Dimensional drawing
Dimensions in mm
Approx. weight 1 g
General technical data
Climatic category (IEC 60068-1) 55/125/56
Max. power (at 25 °C) P25 450 mW
Resistance tolerance ∆RR/RR±10 %
Rated temperature TR25 °C
Dissipation factor (in air) δth approx. 9 mW/K
Dissipation factor (on chassis) δth approx. 20 mW/K
Thermal cooling time constant (in air) τcapprox. 75 s
Thermal cooling time constant (on chassis) τcapprox. 15 s
Torque approx. 0.5 Nm
Insulation resistance (V = 100 V DC) Rins > 100 MΩ
Test voltage (t = 1 s) Vtest 2500 V AC
Temperature measurement B57045K
Probe assemblies K45
Page 2 of 11Please read Cautions and warnings and
Important notes at the end of this document.
Electrical specification and ordering codes
R25
Ω
No. of R/T
characteristic
B25/100
K
Ordering code
1 k 1011 3730 ±3% B57045K0102K000
2.2 k 1013 3900 ±3% B57045K0222K000
4.7 k 4001 3950 ±3% B57045K0472K000
6.8 k 2903 4200 ±3% B57045K0682K000
10 k 2904 4300 ±3% B57045K0103K000
33 k 1012 4300 ±3% B57045K0333K000
47 k 4003 4450 ±3% B57045K0473K000
68 k 2005 4600 ±3% B57045K0683K000
100 k 2005 4600 ±3% B57045K0104K000
150 k 2005 4600 ±3% B57045K0154K000
Reliability data
Test Standard Test conditions ∆R25/R25
(typical)
Remarks
Storage in
dry heat
IEC
60068-2-2
Storage at upper
category temperature
T: 125 °C
t: 1000 h
< 3% No visible
damage
Storage in damp
heat, steady state
IEC
60068-2-78
Temperature of air: 40 °C
Relative humidity of air: 93%
Duration: 56 days
< 3% No visible
damage
Endurance Pmax: 450 mW
t: 1000 h
< 3% No visible
damage
Long-term stability
(empirical value)
Temperature: 100 °C
t: 10000 h
< 5% No visible
damage
Note
Contact of NTC thermistors with any liquids and solvents shall be prevented. It must be
ensured that no water enters the NTC thermistors (e.g. through plug terminals).
Avoid dewing and condensation unless thermistor is specified for these conditions.
Temperature measurement B57045K
Probe assemblies K45
Page 3 of 11Please read Cautions and warnings and
Important notes at the end of this document.
R/T characteristics
R/T No. 1011 1012 1013
T (°C) B25/100 = 3730 K B25/100 = 4300 K B25/100 = 3900 K
RT/R25 α(%/K) RT/R25 α(%/K) RT/R25 α(%/K)
55.0 70.014 6.9 87.237 6.8 77.285 7.0
50.0 49.906 6.7 62.264 6.7 54.938 6.7
45.0 36.015 6.4 44.854 6.5 39.507 6.5
40.0 26.296 6.2 32.599 6.3 28.722 6.3
35.0 19.411 6.0 23.893 6.1 21.099 6.1
30.0 14.479 5.8 17.654 6.0 15.652 5.9
25.0 10.903 5.6 13.098 5.8 11.715 5.7
20.0 8.2923 5.4 9.8059 5.7 8.8541 5.6
15.0 6.3591 5.2 7.4266 5.5 6.7433 5.4
10.0 4.9204 5.1 5.6677 5.4 5.1815 5.2
5.0 3.8279 4.9 4.3213 5.3 4.0099 5.1
0.0 3.0029 4.8 3.3208 5.1 3.1283 4.9
5.0 2.3773 4.6 2.5842 5.0 2.4569 4.8
10.0 1.8959 4.5 2.0238 4.9 1.9438 4.6
15.0 1.5207 4.3 1.5858 4.8 1.5475 4.5
20.0 1.228 4.2 1.2507 4.7 1.2403 4.4
25.0 1.0000 4.1 1.0000 4.5 1.0000 4.3
30.0 0.81779 3.9 0.7964 4.4 0.81104 4.1
35.0 0.67341 3.8 0.64053 4.3 0.66146 4.0
40.0 0.55747 3.7 0.51772 4.2 0.54254 3.9
45.0 0.46357 3.6 0.41958 4.1 0.44727 3.8
50.0 0.3874 3.6 0.34172 4.1 0.37067 3.7
55.0 0.32368 3.5 0.27877 4.0 0.30865 3.6
60.0 0.272 3.4 0.22861 3.9 0.25825 3.5
65.0 0.23041 3.3 0.18872 3.8 0.21707 3.4
70.0 0.19604 3.2 0.15645 3.7 0.18323 3.3
75.0 0.16735 3.1 0.13012 3.6 0.15535 3.3
80.0 0.14342 3.0 0.10863 3.6 0.13223 3.2
85.0 0.12347 3.0 0.091115 3.5 0.11302 3.1
90.0 0.10668 2.8 0.0767 3.4 0.096951 3.0
95.0 0.092734 2.8 0.064867 3.3 0.083487 3.0
100.0 0.080903 2.8 0.055047 3.3 0.072139 2.9
105.0 0.070616 2.7 0.046797 3.2 0.062559 2.8
110.0 0.061826 2.6 0.039904 3.1 0.054425 2.8
115.0 0.054282 2.6 0.034255 3.1 0.047508 2.7
120.0 0.047793 2.5 0.029498 3.0 0.041594 2.6
125.0 0.042249 2.4 0.025448 3.0 0.036532 2.6
Temperature measurement B57045K
Probe assemblies K45
Page 4 of 11Please read Cautions and warnings and
Important notes at the end of this document.
R/T characteristics
R/T No. 2005 2903 2904
T (°C) B25/100 = 4600 K B25/100 = 4200 K B25/100 = 4300 K
RT/R25 α(%/K) RT/R25 α(%/K) RT/R25 α(%/K)
55.0 120.22 7.0 120.03 7.7 121.46 7.4
50.0 85.48 6.9 82.38 7.4 84.439 7.2
45.0 61.004 6.8 57.248 7.2 59.243 7.1
40.0 43.712 6.7 40.255 7.0 41.938 6.9
35.0 31.459 6.6 28.627 6.7 29.947 6.7
30.0 22.746 6.6 20.577 6.6 21.567 6.6
25.0 16.49 6.4 14.876 6.4 15.641 6.3
20.0 12.071 6.3 10.88 6.1 11.466 6.2
15.0 8.8455 6.1 8.0808 5.9 8.451 6.0
10.0 6.5446 6.0 6.0612 5.8 6.2927 5.9
5.0 4.8852 5.8 4.5649 5.6 4.7077 5.7
0.0 3.6781 5.6 3.4708 5.4 3.5563 5.5
5.0 2.7944 5.4 2.6625 5.2 2.7119 5.3
10.0 2.1391 5.3 2.0599 5.1 2.086 5.1
15.0 1.6507 5.1 1.6069 4.9 1.6204 5.0
20.0 1.2823 5.1 1.2631 4.8 1.2683 4.8
25.0 1.0000 5.0 1.0000 4.6 1.0000 4.7
30.0 0.78393 4.8 0.79593 4.5 0.7942 4.6
35.0 0.61822 4.7 0.63796 4.4 0.63268 4.5
40.0 0.49053 4.6 0.51467 4.2 0.5074 4.3
45.0 0.39116 4.5 0.41887 4.1 0.41026 4.2
50.0 0.31371 4.3 0.34272 4.0 0.33363 4.1
55.0 0.25338 4.2 0.28081 3.9 0.27243 4.0
60.0 0.20565 4.2 0.23141 3.8 0.2237 3.9
65.0 0.16762 4.1 0.19211 3.7 0.18459 3.8
70.0 0.13726 4.0 0.16027 3.6 0.15305 3.7
75.0 0.11279 3.9 0.13421 3.5 0.12755 3.6
80.0 0.093053 3.8 0.11288 3.4 0.10677 3.5
85.0 0.077177 3.7 0.095326 3.3 0.089928 3.4
90.0 0.064263 3.6 0.080828 3.2 0.076068 3.3
95.0 0.053678 3.6 0.068916 3.2 0.064524 3.3
100.0 0.044996 3.5 0.058989 3.1 0.054941 3.2
105.0 0.037917 3.4 0.050701 3.0 0.047003 3.1
110.0 0.032063 3.4 0.043735 3.0 0.040358 3.0
115.0 0.027161 3.3 0.037778 2.9 0.034743 3.0
120.0 0.023079 3.2 0.032736 2.8 0.030007 2.9
125.0 0.01968 3.2 0.028513 2.7 0.026006 2.8
130.0 0.022609 2.8
135.0 0.01972 2.7
140.0 0.017251 2.6
145.0 0.015139 2.6
150.0 0.013321 2.5
155.0 0.011754 2.5
Temperature measurement B57045K
Probe assemblies K45
Page 5 of 11Please read Cautions and warnings and
Important notes at the end of this document.
R/T characteristics
R/T No. 4001 4003
T (°C) B25/100 = 3950 K B25/100 = 4450 K
RT/R25 α(%/K) RT/R25 α(%/K)
55.0 88.052 7.3 103.81 6.8
50.0 61.65 7.0 73.707 6.7
45.0 43.727 6.8 52.723 6.6
40.0 31.395 6.5 37.988 6.5
35.0 22.802 6.3 27.565 6.4
30.0 16.742 6.2 20.142 6.2
25.0 12.367 6.0 14.801 6.1
20.0 9.2353 5.6 10.976 5.9
15.0 7.0079 5.4 8.1744 5.8
10.0 5.3654 5.4 6.1407 5.7
5.0 4.126 5.2 4.6331 5.5
0.0 3.2 5.0 3.5243 5.4
5.0 2.4986 4.9 2.6995 5.3
10.0 1.9662 4.7 2.0831 5.1
15.0 1.5596 4.6 1.6189 5.0
20.0 1.2457 4.5 1.2666 4.9
25.0 1.0000 4.4 1.0000 4.7
30.0 0.80355 4.2 0.78351 4.6
35.0 0.65346 4.1 0.62372 4.5
40.0 0.53456 4.0 0.49937 4.4
45.0 0.43966 3.9 0.40218 4.3
50.0 0.36357 3.8 0.32557 4.2
55.0 0.30183 3.7 0.26402 4.1
60.0 0.25189 3.6 0.21527 4.0
65.0 0.21136 3.5 0.17693 3.9
70.0 0.17819 3.4 0.14616 3.8
75.0 0.15089 3.3 0.12097 3.7
80.0 0.12833 3.2 0.10053 3.7
85.0 0.10948 3.1 0.083761 3.6
90.0 0.093748 3.0 0.070039 3.5
95.0 0.080764 2.9 0.058937 3.4
100.0 0.069842 2.9 0.049777 3.4
105.0 0.060455 2.9 0.042146 3.3
110.0 0.052498 2.8 0.035803 3.2
115.0 0.04574 2.7 0.030504 3.2
120.0 0.039972 2.7 0.026067 3.1
125.0 0.034984 2.6 0.022332 3.0
130.0 0.019186 3.0
135.0 0.016515 2.9
140.0 0.014253 2.9
145.0 0.012367 2.8
150.0 0.010758 2.8
155.0 0.0093933 2.7
Temperature measurement B57045K
Probe assemblies K45
Page 6 of 11Please read Cautions and warnings and
Important notes at the end of this document.
Cautions and warnings
See "Important notes".
Storage
Store thermistors only in original packaging. Do not open the package prior to storage.
Storage conditions in original packaging: storage temperature 25 °C ... +45 °C, relative
humidity ≤75% annual mean, <95% maximum 30 days per annum, dew precipitation is
inadmissible.
Do not store thermistors where they are exposed to heat or direct sunlight. Otherwise, the
packing material may be deformed or components may stick together, causing problems during
mounting.
Avoid contamination of thermistor surface during storage, handling and processing.
Avoid storage of thermistors in harmful environments like corrosive gases (SOx, Cl etc).
Use the components as soon as possible after opening the factory seals, i.e. the
polyvinyl-sealed packages.
Solder thermistors within the time specified after shipment from EPCOS.
For leaded components this is 24 months, for SMD components with nickel barrier termination
12 months, for SMD components with AgPd termination 6 months.
Handling
NTC thermistors must not be dropped. Chip-offs or any other damage must not be caused
during handling of NTCs.
Do not touch components with bare hands. Gloves are recommended.
Avoid contamination of thermistor surface during handling.
Washing processes may damage the product due to the possible static or cyclic mechanical
loads (e.g. ultrasonic cleaning). They may cause cracks to develop on the product and its parts,
which might lead to reduced reliability or lifetime.
Bending / twisting leads
A lead (wire) may be bent at a minimum distance of twice the wire’s diameter plus 4 mm from
the component head or housing. When bending ensure the wire is mechanically relieved at the
component head or housing. The bending radius should be at least 0.75 mm.
Twisting (torsion) by 180°of a lead bent by 90°is permissible at 6 mm from the bottom of the
thermistor body.
Soldering
Use resin-type flux or non-activated flux.
Insufficient preheating may cause ceramic cracks.
Rapid cooling by dipping in solvent is not recommended.
Complete removal of flux is recommended.
Temperature measurement B57045K
Probe assemblies K45
Page 7 of 11Please read Cautions and warnings and
Important notes at the end of this document.
Mounting
Ensure that no thermo-mechanical stress occurs due to production processes (curing or
overmolding processes) when thermistors are sealed, potted or overmolded or during their
subsequent operation. The maximum temperature of the thermistor must not be exceeded.
Ensure that the materials used (sealing/potting compound and plastic material) are chemically
neutral.
Electrodes/contacts must not be scratched or damaged before/during/after the mounting
process.
Contacts and housing used for assembly with the thermistor must be clean before mounting.
Ensure that adjacent materials are designed for operation at temperatures comparable to the
surface temperature of the thermistor. Be sure that surrounding parts and materials can
withstand the temperature.
Avoid contamination of the thermistor surface during processing.
The connections of sensors (e.g. cable end, wire end, plug terminal) may only be exposed to
an environment with normal atmospheric conditions.
Tensile forces on cables or leads must be avoided during mounting and operation.
Bending or twisting of cables or leads directly on the thermistor body is not permissible.
Avoid using chemical substances as mounting aids. It must be ensured that no water or other
liquids enter the NTC thermistors (e.g. through plug terminals). In particular, water based
substances (e.g. soap suds) must not be used as mounting aids for sensors.
Operation
Use thermistors only within the specified operating temperature range.
Use thermistors only within the specified power range.
Environmental conditions must not harm the thermistors. Only use the thermistors under
normal atmospheric conditions or within the specified conditions.
Contact of NTC thermistors with any liquids and solvents shall be prevented. It must be
ensured that no water enters the NTC thermistors (e.g. through plug terminals). For
measurement purposes (checking the specified resistance vs. temperature), the component
must not be immersed in water but in suitable liquids (e.g. Galden).
Avoid dewing and condensation unless thermistor is specified for these conditions.
Bending or twisting of cables and/or wires is not permissible during operation of the sensor in
the application.
Be sure to provide an appropriate fail-safe function to prevent secondary product damage
caused by malfunction.
This listing does not claim to be complete, but merely reflects the experience of EPCOS AG.
Temperature measurement B57045K
Probe assemblies K45
Page 8 of 11Please read Cautions and warnings and
Important notes at the end of this document.
Symbols and terms
Symbol English German
A Area Fläche
AWG American Wire Gauge Amerikanische Norm für Drahtquerschnitte
B B value B-Wert
B25/100 B value determined by resistance
measurement at 25 °C and 100 °C
B-Wert, ermittelt durch Widerstands-
messungen bei 25 °C und 100 °C
Cth Heat capacitance Wärmekapazität
I Current Strom
N Number (integer) Anzahl (ganzzahliger Wert)
P25 Maximum power at 25 °C Maximale Leistung bei 25 °C
Pdiss Power dissipation Verlustleistung
Pel Electrical power Elektrische Leistung
Pmax Maximum power within stated
temperature range
Maximale Leistung im
angegebenenTemperaturbereich
∆RB/RBResistance tolerance caused by
spread of B value
Widerstandstoleranz, die durch die
Streuung des B-Wertes verursacht wird
Rins Insulation resistance Isolationswiderstand
RPParallel resistance Parallelwiderstand
RRRated resistance Nennwiderstand
∆RR/RRResistance tolerance Widerstandstoleranz
RSSeries resistance Serienwiderstand
RTResistance at temperature T
(e.g. R25 = resistance at 25 °C)
Widerstand bei Temperatur T
(z.B. R25 = Widerstand bei 25 °C)
T Temperature Temperatur
∆T Temperature tolerance Temperaturtoleranz
t Time Zeit
TAAmbient temperature Umgebungstemperatur
Tmax Upper category temperature Obere Grenztemperatur
(Kategorietemperatur)
Tmin Lower category temperature Untere Grenztemperatur
(Kategorietemperatur)
Top Operating temperature Betriebstemperatur
TRRated temperature Nenntemperatur
Tsurf Surface temperature Oberflächentemperatur
V Voltage Spannung
Vins Insulation test voltage Isolationsprüfspannung
Vop Operating voltage Betriebsspannung
Vtest Test voltage Prüfspannung
Temperature measurement B57045K
Probe assemblies K45
Page 9 of 11Please read Cautions and warnings and
Important notes at the end of this document.
Symbol English German
αTemperature coefficient Temperaturkoeffizient
∆Tolerance, change Toleranz, Änderung
δth Dissipation factor Wärmeleitwert
τcThermal cooling time constant Thermische Abkühlzeitkonstante
τaThermal time constant Thermische Zeitkonstante
Abbreviations / Notes
Symbol English German
Surface-mounted devices Oberflächenmontierbares Bauelement
* To be replaced by a number in ordering
codes, type designations etc.
Platzhalter für Zahl im Bestellnummern-
code oder für die Typenbezeichnung.
+ To be replaced by a letter. Platzhalter für einen Buchstaben.
All dimensions are given in mm. Alle Maße sind in mm angegeben.
The commas used in numerical values
denote decimal points.
Verwendete Kommas in Zahlenwerten
bezeichnen Dezimalpunkte.
Temperature measurement B57045K
Probe assemblies K45
Page 10 of 11Please read Cautions and warnings and
Important notes at the end of this document.
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 re-
quirements 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 incum-
bent on the customer to check and decide whether an EPCOS product with the properties de-
scribed 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 Ma-
terial Data Sheets on the Internet (www.epcos.com/material). Should you have any more de-
tailed 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 fore-
going for customer-specific products.
6. Unless otherwise agreed in individual contracts, all orders are subject to the current ver-
sion of the "General Terms of Delivery for Products and Services in the Electrical In-
dustry" published by the German Electrical and Electronics Industry Association
(ZVEI).
7. The trade names EPCOS, BAOKE, Alu-X, CeraDiode, CeraLink, CSMP, CSSP, CTVS,
DeltaCap, DigiSiMic, DSSP, FilterCap, FormFit, MiniBlue, MiniCell, MKD, MKK, MLSC,
MotorCap, PCC, PhaseCap, PhaseCube, PhaseMod, PhiCap, SIFERRIT, SIFI, SIKOREL,
SilverCap, SIMDAD, SiMic, 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.
Important notes
Page 11 of 11
