NTC thermistors for
temperature measurement
Leaded NTC thermistors,
lead spacing 2.5 mm
Series/Type:
B57891M
Date:
January 2018
© EPCOS AG 2018. 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.
Temperature measurement and compensation
B57891M
Leaded NTC thermistors, lead spacing 2.5 mm
M891
Applications
Temperature measurement and
compensation
Dimensional drawing
Features
Wide resistance range
Cost-effective
Lacquer-coated thermistor disk
Leads: copper-clad Fe wire, tinned
Marked with resistance and tolerance
Options
Lead spacing 5 mm available on request
Delivery mode
Bulk (standard), cardboard tape, reeled or in
Ammo pack on request
Dimensions in mm
Approx. weight 200 mg
General technical data
Climatic category
Max. power
Resistance tolerance
Rated temperature
Dissipation factor
Thermal cooling time constant
Heat capacity
(IEC 60068-1)
(at 25 °C)
(in air)
(in air)
P25
∆RR/RR
TR
δth
τc
Cth
40/125/56
200
±5, ±10
25
approx. 3.5
approx. 12
approx. 40
mW
%
°C
mW/K
s
mJ/K
Electrical specification and ordering codes
R25
Ω
1k
1.5 k
2.2 k
3.3 k
4.7 k
6.8 k
10 k
15 k
22 k
No. of R/T
characteristic
1009
1008
1013
2003
2003
2003
4901
2004
2904
B25/100
K
3930 ±3%
3560 ±3%
3900 ±3%
3980 ±3%
3980 ±3%
3980 ±3%
3950 ±3%
4100 ±3%
4300 ±3%
+ = Resistance tolerance
J = ±5%
K = ±10%
Please read Cautions and warnings and
Important notes at the end of this document.
Page 2 of 29
Ordering code
B57891M0102+000
B57891M0152+000
B57891M0222+000
B57891M0332+000
B57891M0472+000
B57891M0682+000
B57891M0103+000
B57891M0153+000
B57891M0223+000
Temperature measurement and compensation
B57891M
Leaded NTC thermistors, lead spacing 2.5 mm
M891
R25
Ω
33 k
47 k
100 k
150 k
220 k
330 k
470 k
No. of R/T
characteristic
2904
4012
4003
2005
2005
2007
2006
B25/100
K
4300 ±3%
4355 ±3%
4450 ±3%
4600 ±3%
4600 ±3%
4830 ±3%
5000 ±3%
Ordering code
B57891M0333+000
B57891M0473+000
B57891M0104+000
B57891M0154+000
B57891M0224+000
B57891M0334+000
B57891M0474+000
+ = Resistance tolerance
J = ±5%
K = ±10%
Reliability data
Test
Standard
Storage in
dry heat
IEC
60068-2-2
Storage in damp
heat, steady state
Rapid temperature
cycling
Endurance
Long-term stability
(empirical value)
Test conditions
Storage at upper
category temperature
T: 125 °C
t: 1000 h
IEC
Temperature of air: 40 °C
60068-2-78 Relative humidity of air: 93%
Duration: 56 days
IEC
Lower test temperature: 40 °C
60068-2-14 Upper test temperature: 125 °C
Number of cycles: 100
Pmax: 200 mW
t: 1000 h
Temperature: 70 °C
t: 10000 h
∆R25/R25
(typical)
< 3%
Remarks
< 2%
No visible
damage
< 2%
No visible
damage
< 3%
No visible
damage
No visible
damage
< 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.
Please read Cautions and warnings and
Important notes at the end of this document.
Page 3 of 29
Temperature measurement and compensation
B57891M
Leaded NTC thermistors, lead spacing 2.5 mm
M891
R/T characteristics
R/T No.
T (°C)
1008
1009
1013
B25/100 = 3560 K
B25/100 = 3930 K
B25/100 = 3900 K
RT/R25
α (%/K) RT/R25
α (%/K) RT/R25
α (%/K)
55.0
50.0
45.0
40.0
35.0
53.104
39.318
29.325
22.03
16.666
6.1
6.0
5.8
5.7
5.5
85.423
60.781
43.65
31.629
23.118
7.0
6.8
6.6
6.4
6.2
77.285
54.938
39.507
28.722
21.099
7.0
6.7
6.5
6.3
6.1
30.0
25.0
20.0
15.0
10.0
12.696
9.7251
7.5171
5.8353
4.5686
5.4
5.2
5.1
4.9
4.8
17.04
12.649
9.4864
7.1545
5.4479
6.1
5.9
5.8
5.6
5.4
15.652
11.715
8.8541
6.7433
5.1815
5.9
5.7
5.6
5.4
5.2
5.0
0.0
5.0
10.0
15.0
3.605
2.8665
2.2907
1.8438
1.492
4.7
4.5
4.4
4.3
4.1
4.1732
3.2256
2.5147
1.9763
1.5649
5.2
5.1
4.9
4.8
4.6
4.0099
3.1283
2.4569
1.9438
1.5475
5.1
4.9
4.8
4.6
4.5
20.0
25.0
30.0
35.0
40.0
1.2154
1.0000
0.82976
0.68635
0.57103
4.0
3.9
3.8
3.7
3.6
1.2481
1.0000
0.80956
0.65726
0.53697
4.5
4.3
4.2
4.1
4.0
1.2403
1.0000
0.81104
0.66146
0.54254
4.4
4.3
4.1
4.0
3.9
45.0
50.0
55.0
60.0
65.0
0.48015
0.40545
0.3417
0.28952
0.24714
3.5
3.4
3.3
3.2
3.1
0.44169
0.36534
0.30327
0.25313
0.21271
3.9
3.8
3.7
3.5
3.4
0.44727
0.37067
0.30865
0.25825
0.21707
3.8
3.7
3.6
3.5
3.4
70.0
75.0
80.0
85.0
90.0
0.21183
0.18194
0.1568
0.13592
0.11822
3.1
3.0
2.9
2.8
2.8
0.17962
0.15219
0.12949
0.11067
0.094952
3.4
3.3
3.2
3.1
3.0
0.18323
0.15535
0.13223
0.11302
0.096951
3.3
3.3
3.2
3.1
3.0
95.0
100.0
105.0
110.0
115.0
0.1034
0.090741
0.079642
0.070102
0.061889
2.7
2.6
2.6
2.5
2.4
0.08178
0.07069
0.061383
0.053486
0.04673
3.0
2.9
2.8
2.7
2.7
0.083487
0.072139
0.062559
0.054425
0.047508
3.0
2.9
2.8
2.8
2.7
120.0
125.0
130.0
135.0
140.0
0.054785
0.048706
0.043415
0.038722
0.034615
2.4
2.3
2.3
2.2
2.2
0.040955
0.036006
0.031747
0.028097
0.024935
2.6
2.5
2.5
2.4
2.4
0.041594
0.036532
2.6
2.6
145.0
150.0
155.0
0.031048
0.02791
0.025193
2.1
2.1
2.0
0.022176
0.019772
0.017683
2.3
2.3
2.2
Please read Cautions and warnings and
Important notes at the end of this document.
Page 4 of 29
Temperature measurement and compensation
B57891M
Leaded NTC thermistors, lead spacing 2.5 mm
M891
R/T No.
T (°C)
160.0
165.0
1008
1009
1013
B25/100 = 3560 K
RT/R25
α (%/K)
0.02279
2.0
0.020667
2.0
B25/100 = 3930 K
RT/R25
α (%/K)
B25/100 = 3900 K
RT/R25
α (%/K)
170.0
175.0
180.0
185.0
190.0
0.01878
0.01709
0.015582
0.014227
0.013012
1.9
1.9
1.8
1.8
1.8
195.0
200.0
205.0
210.0
215.0
0.011934
0.010964
0.0101
0.0093191
0.0085949
1.7
1.7
1.7
1.6
1.6
220.0
225.0
230.0
235.0
240.0
0.0079384
0.0073411
0.006798
0.0063087
0.0058623
1.6
1.5
1.5
1.5
1.5
245.0
250.0
0.0054487
0.0050705
1.4
1.4
Please read Cautions and warnings and
Important notes at the end of this document.
Page 5 of 29
Temperature measurement and compensation
B57891M
Leaded NTC thermistors, lead spacing 2.5 mm
M891
R/T characteristics
R/T No.
T (°C)
2003
2004
2005
B25/100 = 3980 K
B25/100 = 4100 K
B25/100 = 4600 K
RT/R25
α (%/K) RT/R25
α (%/K) RT/R25
α (%/K)
55.0
50.0
45.0
40.0
35.0
97.578
67.65
47.538
33.831
24.359
7.5
7.2
7.0
6.7
6.5
99.552
68.582
47.963
34.019
24.448
7.6
7.3
7.0
6.7
6.5
30.0
25.0
20.0
15.0
10.0
17.753
13.067
9.7228
7.3006
5.5361
6.3
6.0
5.8
5.6
5.5
17.787
13.083
9.7251
7.316
5.5545
6.3
6.1
5.8
5.6
5.4
22.746
16.49
12.071
8.8455
6.5446
6.6
6.4
6.3
6.1
6.0
5.0
0.0
5.0
10.0
15.0
4.2332
3.266
2.5392
1.9902
1.5709
5.3
5.1
5.0
4.8
4.7
4.2531
3.2836
2.5512
1.9973
1.5738
5.3
5.1
5.0
4.8
4.7
4.8852
3.6781
2.7944
2.1391
1.6507
5.8
5.6
5.4
5.3
5.1
20.0
25.0
30.0
35.0
40.0
1.2492
1.0000
0.80575
0.65326
0.5329
4.5
4.4
4.3
4.1
4.0
1.2488
1.0000
0.8008
0.64733
0.52628
4.5
4.5
4.3
4.2
4.0
1.2823
1.0000
0.78393
0.61822
0.49053
5.1
5.0
4.8
4.7
4.6
45.0
50.0
55.0
60.0
65.0
0.43715
0.36064
0.29908
0.24932
0.20886
3.9
3.8
3.7
3.6
3.5
0.43263
0.35708
0.29406
0.24342
0.20278
3.9
3.9
3.8
3.7
3.6
0.39116
0.31371
0.25338
0.20565
0.16762
4.5
4.3
4.2
4.2
4.1
70.0
75.0
80.0
85.0
90.0
0.17578
0.14863
0.12621
0.10763
0.092159
3.4
3.3
3.2
3.1
3.1
0.16964
0.14257
0.12028
0.10196
0.086757
3.5
3.4
3.4
3.3
3.3
0.13726
0.11279
0.093053
0.077177
0.064263
4.0
3.9
3.8
3.7
3.6
95.0
100.0
105.0
110.0
115.0
0.079225
0.068356
0.059247
0.051531
0.044921
3.0
2.9
2.8
2.8
2.7
0.073804
0.062974
0.054276
0.046943
0.040576
3.2
3.0
2.9
3.0
2.9
0.053678
0.044996
0.037917
0.032063
0.027161
3.6
3.5
3.4
3.4
3.3
120.0
125.0
130.0
135.0
140.0
0.039282
0.034387
0.030186
0.02665
0.023594
2.7
2.6
2.5
2.5
2.4
0.035174
0.030637
2.8
2.7
0.023079
0.01968
3.2
3.2
145.0
150.0
155.0
0.020931
0.018616
0.016612
2.4
2.3
2.3
Please read Cautions and warnings and
Important notes at the end of this document.
Page 6 of 29
120.22
85.48
61.004
43.712
31.459
7.0
6.9
6.8
6.7
6.6
Temperature measurement and compensation
B57891M
Leaded NTC thermistors, lead spacing 2.5 mm
M891
R/T characteristics
R/T No.
T (°C)
55.0
50.0
45.0
40.0
35.0
2006
2007
2904
B25/100 = 5000 K
B25/100 = 4830 K
B25/100 = 4300 K
RT/R25
α (%/K) RT/R25
α (%/K) RT/R25
α (%/K)
200.55
131.02
87.171
58.988
40.545
8.7
8.3
8.0
7.7
7.4
185.87
123.23
82.888
56.544
39.061
8.4
8.1
7.8
7.6
7.3
121.46
84.439
59.243
41.938
29.947
7.4
7.2
7.1
6.9
6.7
30.0
25.0
20.0
15.0
10.0
28.272
19.997
14.292
10.35
7.5614
7.1
6.9
6.6
6.4
6.4
27.321
19.326
13.823
10.001
7.3067
7.1
6.8
6.6
6.4
6.4
21.567
15.641
11.466
8.451
6.2927
6.6
6.3
6.2
6.0
5.9
5.0
0.0
5.0
10.0
15.0
5.5343
4.086
3.0374
2.276
1.7188
6.2
6.0
5.9
5.7
5.6
5.3454
3.9484
2.9595
2.2358
1.7001
6.2
5.9
5.7
5.6
5.4
4.7077
3.5563
2.7119
2.086
1.6204
5.7
5.5
5.3
5.1
5.0
20.0
25.0
30.0
35.0
40.0
1.3074
1.0000
0.76988
0.5954
0.46341
5.5
5.3
5.2
5.1
4.9
1.3021
1.0000
0.7756
0.60507
0.47498
5.4
5.2
5.0
4.9
4.8
1.2683
1.0000
0.7942
0.63268
0.5074
4.8
4.7
4.6
4.5
4.3
45.0
50.0
55.0
60.0
65.0
0.36327
0.28636
0.2262
0.17974
0.1438
4.8
4.8
4.7
4.5
4.4
0.37533
0.29823
0.23763
0.19041
0.15356
4.7
4.6
4.5
4.4
4.3
0.41026
0.33363
0.27243
0.2237
0.18459
4.2
4.1
4.0
3.9
3.8
70.0
75.0
80.0
85.0
90.0
0.1156
0.093296
0.075623
0.061619
0.050414
4.3
4.3
4.2
4.1
3.9
0.12442
0.10131
0.08286
0.068004
0.056032
4.2
4.1
4.0
3.9
3.8
0.15305
0.12755
0.10677
0.089928
0.076068
3.7
3.6
3.5
3.4
3.3
95.0
100.0
105.0
110.0
115.0
0.041532
0.034355
0.028525
0.023774
0.019852
3.8
3.8
3.7
3.7
3.6
0.046379
0.038533
0.032169
0.026952
0.022658
3.8
3.7
3.6
3.5
3.4
0.064524
0.054941
0.047003
0.040358
0.034743
3.3
3.2
3.1
3.0
3.0
120.0
125.0
130.0
135.0
140.0
0.016632
0.014016
3.5
3.4
0.019111
0.016201
3.3
3.3
0.030007
0.026006
0.022609
0.01972
0.017251
2.9
2.8
2.8
2.7
2.6
145.0
150.0
155.0
0.015139
0.013321
0.011754
2.6
2.5
2.5
Please read Cautions and warnings and
Important notes at the end of this document.
Page 7 of 29
Temperature measurement and compensation
B57891M
Leaded NTC thermistors, lead spacing 2.5 mm
M891
R/T characteristics
R/T No.
T (°C)
55.0
50.0
45.0
40.0
35.0
4003
4012
4901
B25/100 = 4450 K
B25/100 = 4355 K
B25/100 = 3950 K
RT/R25
α (%/K) RT/R25
α (%/K) RT/R25
α (%/K)
103.81
73.707
52.723
37.988
27.565
6.8
6.7
6.6
6.5
6.4
115.76
80.102
56.067
39.677
28.374
7.5
7.2
7.0
6.8
6.6
87.89
61.759
43.934
31.618
23.006
7.1
6.9
6.7
6.5
6.3
30.0
25.0
20.0
15.0
10.0
20.142
14.801
10.976
8.1744
6.1407
6.2
6.1
5.9
5.8
5.7
20.496
14.949
11.004
8.1721
6.1208
6.4
6.2
6.0
5.9
5.7
16.915
12.555
9.4143
7.1172
5.4308
6.1
5.9
5.7
5.5
5.4
5.0
0.0
5.0
10.0
15.0
4.6331
3.5243
2.6995
2.0831
1.6189
5.5
5.4
5.3
5.1
5.0
4.6219
3.5176
2.6973
2.0834
1.6205
5.5
5.4
5.2
5.1
5.0
4.1505
3.2014
2.5011
1.9691
1.5618
5.2
5.0
4.9
4.7
4.6
20.0
25.0
30.0
35.0
40.0
1.2666
1.0000
0.78351
0.62372
0.49937
4.9
4.7
4.6
4.5
4.4
1.2689
1.0000
0.79302
0.63266
0.50765
4.8
4.7
4.6
4.5
4.3
1.2474
1.0000
0.808
0.6569
0.5372
4.5
4.3
4.2
4.1
4.0
45.0
50.0
55.0
60.0
65.0
0.40218
0.32557
0.26402
0.21527
0.17693
4.3
4.2
4.1
4.0
3.9
0.40961
0.33229
0.27096
0.22206
0.18287
4.2
4.1
4.0
3.9
3.8
0.44235
0.3661
0.30393
0.25359
0.21283
3.9
3.8
3.7
3.6
3.5
70.0
75.0
80.0
85.0
90.0
0.14616
0.12097
0.10053
0.083761
0.070039
3.8
3.7
3.7
3.6
3.5
0.1513
0.12574
0.10496
0.087977
0.074045
3.7
3.7
3.6
3.5
3.4
0.17942
0.15183
0.12901
0.11002
0.094179
3.4
3.3
3.2
3.1
3.1
95.0
100.0
105.0
110.0
115.0
0.058937
0.049777
0.042146
0.035803
0.030504
3.4
3.4
3.3
3.2
3.2
0.062565
0.053067
0.045177
0.038597
0.03309
3.3
3.3
3.2
3.1
3.0
0.080896
0.069722
0.060397
0.052493
0.045733
3.0
2.9
2.9
2.8
2.7
120.0
125.0
130.0
135.0
140.0
0.026067
0.022332
0.019186
0.016515
0.014253
3.1
3.0
3.0
2.9
2.9
0.028464
0.024564
3.0
2.9
0.039963
0.035059
0.030844
0.027192
0.024034
2.7
2.6
2.6
2.5
2.4
145.0
150.0
155.0
0.012367
0.010758
0.0093933
2.8
2.8
2.7
0.021285
0.018895
0.016813
2.4
2.4
2.3
Please read Cautions and warnings and
Important notes at the end of this document.
Page 8 of 29
Temperature measurement and compensation
B57891M
Leaded NTC thermistors, lead spacing 2.5 mm
M891
Taping and packing
1
Taping of SMD NTC thermistors
Tape and reel packing according to IEC 60286-3.
Tape material: Cardboard or blister, tape width 8 ±0.30 mm
2
Reel packing
Dimensions in mm
8-mm tape
180-mm reel
330-mm reel
A
180 +0/3
330 +0/2.0
W1
8.4 +1.5/0
8.4 +1.5/0
W2
14.4 max.
14.4 max.
Leader, trailer
Please read Cautions and warnings and
Important notes at the end of this document.
Page 9 of 29
Temperature measurement and compensation
B57891M
Leaded NTC thermistors, lead spacing 2.5 mm
M891
Packing units for discrete chip
Case size
Chip thickness
inch/mm
0402/1005
0603/1608
0805/2012
1206/3216
3
th
0.5 mm
0.8 mm
0.8 mm
1.2 mm
0.8 mm
1.2 mm
Cardboard tape Blister tape
W
8 mm
8 mm
W
8 mm
8 mm
8 mm
8 mm
8 mm
∅ 180-mm reel ∅ 330-mm reel
pcs.
10000
4000
2000/ 4000
3000
2000
4000
pcs.
50000
16000
16000
12000
12000
12000
Packing codes
The last two digits of the complete ordering code state the packing mode:
Last two digits
60
SMD
Cardboard tape
180-mm reel packing
62
SMD
Blister tape
180-mm reel packing
70
SMD
Cardboard tape
330-mm reel packing
72
SMD
Blister tape
330-mm reel packing
Please read Cautions and warnings and
Important notes at the end of this document.
Page 10 of 29
Temperature measurement and compensation
B57891M
Leaded NTC thermistors, lead spacing 2.5 mm
M891
4
Taping of radial leaded NTC thermistors
Dimensions and tolerances
Lead spacing F = 2.5 mm and 5.0 mm (taping to IEC 60286-2)
Dimensions (mm)
w
th
d
P0
P1
F
∆h
∆p
W
W0
W1
W2
H
H0
H1
D0
t
L
L1
Lead
spacing
2.5 mm
11.0
5.0
0.5/0.6
12.7
5.1
2.5
0
0
18.0
5.5
9.0
3.0
18.0
16.0
32.2
4.0
0.9
11.0
4.0
Lead
spacing
5 mm
11.5
6.0
0.5/0.6
12.7
3.85
5.0
0
0
18.0
5.5
9.0
3.0
18.0
16.0
32.2
4.0
0.9
11.0
4.0
Please read Cautions and warnings and
Important notes at the end of this document.
Tolerance of
lead spacing
2.5/5 mm
max.
max.
±0.05
±0.3
±0.7
+0.6/0.1
±2.0
±1.3
±0.5
min.
+0.75/0.5
max.
+2.0/0
±0.5
max.
±0.2
max.
max.
max.
Remarks
±1 mm / 20 sprocket holes
measured at top of component body
peel-off force ≥5 N
without wires
Page 11 of 29
Temperature measurement and compensation
B57891M
Leaded NTC thermistors, lead spacing 2.5 mm
M891
Types of packing
Ammo packing
Ammo
type
x
y
z
I
80
240
210
Packing unit: 1000 - 2000 pcs./reel
Reel packing
Packing unit: 1000 - 2000 pcs./reel
Reel dimensions (in mm)
Reel type
d
f
n
w
I
360 max.
31 ±1
approx. 45
54 max.
Please read Cautions and warnings and
Important notes at the end of this document.
Page 12 of 29
Temperature measurement and compensation
B57891M
Leaded NTC thermistors, lead spacing 2.5 mm
M891
Cassette packing
Packing unit: 1000 - 2000 pcs./cassette
Bulk packing
The components are packed in cardboard boxes, the size of which depends on the order quantity.
Please read Cautions and warnings and
Important notes at the end of this document.
Page 13 of 29
Temperature measurement and compensation
B57891M
Leaded NTC thermistors, lead spacing 2.5 mm
M891
5
Packing codes
The last two digits of the complete ordering code state the packing mode:
Last two digits
00, 01, 02, 03,04,
05, 06, 07, 08
Bulk
40, 41
Bulk
45
Bulk
50
Radial leads, kinked
Cardboard tape
Cassette packing
51
Radial leads, kinked
Cardboard tape
360-mm reel packing
52
Radial leads, straight
Cardboard tape
Cassette packing
53
Radial leads, straight
Cardboard tape
360-mm reel packing
54
Radial leads, kinked
Cardboard tape
AMMO packing
55
Radial leads, straight
Cardboard tape
AMMO packing
(If no packing code is indicated, this corresponds to 40)
Example 1:
B57164K0102J000
B57164K0102J052
Bulk
Cardboard tape, cassette packing
Example 2:
B57881S0103F002
B57881S0103F251
Bulk
Cardboard tape, reel packing
Please read Cautions and warnings and
Important notes at the end of this document.
Page 14 of 29
Temperature measurement and compensation
B57891M
Leaded NTC thermistors, lead spacing 2.5 mm
M891
Mounting instructions
1
Soldering
1.1
Leaded NTC thermistors
Leaded thermistors comply with the solderability requirements specified by CECC.
When soldering, care must be taken that the NTC thermistors are not damaged by excessive
heat. The following maximum temperatures, maximum time spans and minimum distances have
to be observed:
Bath temperature
Dip soldering
Iron soldering
max. 260 °C
max. 360 °C
Soldering time
max. 4 s
max. 2 s
Distance from thermistor
min. 6 mm
min. 6 mm
Under more severe soldering conditions the resistance may change.
1.1.1
Wave soldering
Temperature characteristic at component terminal with dual wave soldering
1.2
Leadless NTC thermistors
In case of NTC thermistors without leads, soldering is restricted to devices which are provided
with a solderable metallization. The temperature shock caused by the application of hot solder
may produce fine cracks in the ceramic, resulting in changes in resistance.
To prevent leaching of the metallization, solder with silver additives or with a low tin content
Please read Cautions and warnings and
Important notes at the end of this document.
Page 15 of 29
Temperature measurement and compensation
B57891M
Leaded NTC thermistors, lead spacing 2.5 mm
M891
should be used. In addition, soldering methods should be employed which permit short soldering
times.
1.3
SMD NTC thermistors
SMD NTC thermistors can be provided with a nickel barrier termination or on special request with
silver-palladium termination. The use of no-clean solder products is recommended. In any case
mild, non-activated fluxes should be used. Flux residues after soldering should be minimized.
SMD NTCs with AgPd termination are not approved for lead-free soldering.
Nickel barrier termination
Figure 1
SMD NTC thermistors, structure of nickel
barrier termination
The nickel barrier layer of the silver/nickel/tin termination (see figure 1) prevents leaching of the
silver base metallization layer. This allows great flexibility in the selection of soldering parameters.
The tin prevents the nickel layer from oxidizing and thus ensures better wetting by the solder. The
nickel barrier termination is tested for all commonly-used soldering methods according to IEC
60068-2-58. Insufficient preheating may cause ceramic cracks. Rapid cooling by dipping in solvent is not recommended.
The following test and process conditions apply for nickel barrier termination.
Please read Cautions and warnings and
Important notes at the end of this document.
Page 16 of 29
Temperature measurement and compensation
B57891M
Leaded NTC thermistors, lead spacing 2.5 mm
M891
1.3.1
Solderability (test to IEC 60068-2-58)
Preconditioning: Immersion into flux F-SW 32.
Evaluation criterion: Wetting of soldering areas ≥95%.
Solder
Bath temperature (°C)
Dwell time (s)
SnPb 60/40
215 ±3
3 ±0.3
SnAg (3.0 ... 4.0), Cu (0.5 ... 0.9)
245 ±3
3 ±0.3
1.3.2
Resistance to soldering heat (test to IEC 60068-2-58)
Preconditioning: Immersion into flux F-SW 32.
Evaluation criterion: Leaching of side edges ≤1/3.
Solder
Bath temperature (°C)
Dwell time (s)
SnPb 60/40
260 ±5
10 ±1
SnAg (3.0 ... 4.0), Cu (0.5 ... 0.9)
260 ±5
10 ±1
1.3.3
Reflow soldering
Temperature ranges for reflow soldering acc. to IEC 60068-2-58 recommendations.
Please read Cautions and warnings and
Important notes at the end of this document.
Page 17 of 29
Temperature measurement and compensation
B57891M
Leaded NTC thermistors, lead spacing 2.5 mm
M891
Profile feature
Preheat and soak
- Temperature min
- Temperature max
- Time
Sn-Pb eutectic assembly
Pb-free assembly
Tsmin
Tsmax
tsmin to tsmax
100 °C
150 °C
60 ... 120 s
150 °C
200 °C
60 ... 120 s
Average ramp-up rate
Tsmax to Tp
3 °C/ s max.
3 °C/ s max.
Liquidous temperature
Time at liquidous
TL
tL
183 °C
40 ... 150 s
217 °C
40 ... 150 s
Peak package body temperature
Tp
215 °C ... 260 °C1)
235 °C ... 260 °C
Time above (TP 5 °C)
tp
10 ... 40 s
10 ... 40 s
Average ramp-down rate
Tp to Tsmax
6 °C/ s max.
6 °C/ s max.
max. 8 minutes
max. 8 minutes
Time 25 °C to peak temperature
1) Depending on package thickness.
Notes:
All temperatures refer to topside of the package, measured on the package body
surface.
Number of reflow cycles: 3
Iron soldering should be avoided, hot air methods are recommended for repair
purposes.
Solder joint profiles for silver/nickel/tin terminations
Please read Cautions and warnings and
Important notes at the end of this document.
Page 18 of 29
Temperature measurement and compensation
B57891M
Leaded NTC thermistors, lead spacing 2.5 mm
M891
1.3.4
Recommended geometry of solder pads
Recommended maximum dimensions (mm)
Case size
inch/mm
A
B
C
0402/1005
0.6
0.6
1.7
0603/1608
1.0
1.0
3.0
0805/2012
1.3
1.2
3.4
1206/3216
1.8
1.2
4.5
2
Conductive adhesion
An alternative to soldering for silver-palladium terminated components is the gluing of thermistors
with conductive adhesives. The benefit of this method is that it involves no thermal stress. The
adhesives used must be chemically inert.
3
Clamp contacting
Pressure contacting by means of clamps is particularly suitable for applications involving frequent
switching and high turn-on powers.
4
Robustness of terminations (leaded types)
The leads meet the requirements of IEC 60068-2-21. They may not be bent closer than 4 mm
from the solder joint on the thermistor body or from the point at which they leave the feedthroughs. During bending, any mechanical stress at the outlet of the leads must be removed. The
bending radius should be at least 0.75 mm.
Please read Cautions and warnings and
Important notes at the end of this document.
Page 19 of 29
Temperature measurement and compensation
B57891M
Leaded NTC thermistors, lead spacing 2.5 mm
M891
Tensile strength:
Test Ua1:
Value of applied force for Ua1 test:
Diameter (d) of
Force with tolerance of ±10%
corresponding round leads
∅ ≤ 0.25 mm
1.0 N
0.25 < ∅ ≤ 0.35 mm
2.5 N
0.35 < ∅ ≤ 0.50 mm
5.0 N
0.50 < ∅ ≤ 0.80 mm
10.0 N
Bending strength: Test Ub:
Two 90°-bends in opposite directions
Value of applied force for Ub test:
Diameter (d) of
Force with tolerance of ±10%
corresponding round leads
∅ ≤ 0.25 mm
0.5 N
0.25 < ∅ ≤ 0.35 mm
1.25 N
0.35 < ∅ ≤ 0.50 mm
2.5 N
0.50 < ∅ ≤ 0.80 mm
5N
Torsional strength: Test Uc: severity 2
The lead is bent by 90° at a distance of 6 to 6.5 mm from the thermistor body.
The bending radius of the leads should be approx. 0.75 mm. Two torsions of
180° each (severity 2).
When subjecting leads to mechanical stress, the following should be observed:
Tensile stress on leads
During mounting and operation tensile forces on the leads are to be avoided.
Bending of leads
Bending of the leads directly on the thermistor body is not permissible.
A lead may be bent at a minimum distance of twice the wire's diameter +4 mm from the solder
joint on the thermistor body. During bending the wire must be mechanically relieved at its outlet.
The bending radius should be at least 0.75 mm.
Please read Cautions and warnings and
Important notes at the end of this document.
Page 20 of 29
Temperature measurement and compensation
B57891M
Leaded NTC thermistors, lead spacing 2.5 mm
M891
5
Sealing and potting
Sealing or potting processes can affect the reliability of the component.
When thermistors are sealed, potted or overmolded, there must be no mechanical stress caused
by thermal expansion during the production process (curing / overmolding process) and during
later operation. The upper category temperature of the thermistor must not be exceeded. Ensure
that the materials used (sealing / potting compound and plastic material) are chemically neutral.
As thermistors are temperature sensitive components it should be considered that molding can affect the thermal surrounding and may influence e.g. the response time.
Extensive testing is encouraged in order to determine whether overmolding or potting influences
the functionality and/ or reliability of the component.
6
Cleaning
Cleaning processes can affect the reliability of the component.
If cleaning is necessary, mild cleaning agents are recommended. Cleaning agents based on water are not allowed. Washing processes may damage the product due to the possible static or
cyclic mechanical loads (e.g. ultrasonic cleaning). They may cause cracks which might lead to reduced reliability and/ or lifetime.
7
Storage
In order to maintain their solderability, thermistors must be stored in a non-corrosive atmosphere.
Humidity, temperature and container materials are critical factors.
Do not store SMDs where they are exposed to heat or direct sunlight. Otherwise, the packing material may be deformed or SMDs may stick together, causing problems during mounting. After
opening the factory seals, such as polyvinyl-sealed packages, use the SMDs as soon as possible.
The components should be left in the original packing. Touching the metallization of unsoldered
thermistors may change their soldering properties.
Storage temperature:
25 °C up to 45 °C
Relative humidity (without condensation):
≤75% annual mean