B57220K0212A003 Datasheet, PDF (5/12 Pages) EPCOS – NTC thermistors for temperature measurement

Temperature measurement and compensation
Leadless NTCs
B57220K
K220
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
Soldering time
Distance from thermistor
Dip soldering
max. 260 °C
max. 4 s
min. 6 mm
Iron soldering
max. 360 °C
max. 2 s
min. 6 mm
Under more severe soldering conditions the resistance may change.
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
should be used. In addition, soldering methods should be employed which permit short soldering
times.
2
Clamp contacting
Pressure contacting by means of clamps is particularly suitable for applications involving frequent
switching and high turn-on powers.
3
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 feed-
throughs. During bending, any mechanical stress at the outlet of the leads must be removed. The
bending radius should be at least 0.75 mm.
Tensile strength:
Test Ua1:
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
0.80 < ∅ ≤1.25 mm = 20.0 N
Please read Cautions and warnings and
Important notes at the end of this document.
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