Axial Leaded Glass Encapsulated Diode DO35 Shape NTC Thermistor Temperature Sensor, 20K Ohm, Beta B(25/50): 3950K, Operating Temperature Range -40C to +250C.

AMWEI Product Code: AMF58-203G3950

Appearance Dimension 

Axial Glass NTC Thermistor Temperature Sensor Dimension

Unit: mm

  • NTC Thermistor chip hermetically sealed in DO35 glass shell.
  • Tinned Dumet wire

Axial Glass NTC Thermistor Application

Axial lead glass encapsulated NTC thermistor used for high temperature measurement, sensing, monitoring, detection and control. Typical application such as  industrial process control, HVAC, oven,  office equipment, etc.

AMWEI Axial Glass Encapsulated NTC Thermistor Electric Characteristics Data

  • Resistance at 25C R25: 20K ohm+/-2%
  • Beta Value B(25/50): 3950K+/-1%
  • Optional R25 resistance tolerance,  ±1%(F), ±2%(G), ±3%(H), or ±5%(J)
  • Dissipation Factor:  δ≥2mW/℃
  • Thermal Time Constant (in still air): 12 seconds max.
  • Rated Power: ≤50mW
  • Insulation resistance: room temperature, 50VDC, 60 Seconds, ≥100MΩ.
  • Operating temperature range: -40 to +250C.

NTC 20K Ohm 3950K Resistance vs. Temperature RT Data

(K Ohm)
(K Ohm )
(K Ohm)
-40C 699.295 KΩ 80C 2.526 KΩ 200C 0.135 KΩ
-35C 497.852 KΩ 85C 2.155 KΩ 205C 0.123 KΩ
-30C 359.261 KΩ 90C 1.846 KΩ 210C 0.113 KΩ
-25C 262.710 KΩ 95C 1.587 KΩ 215C 0.103 KΩ
-20C 194.541 KΩ 100C 1.369 KΩ 220C 0.095 KΩ
-15C 145.760 KΩ 105C 1.186 KΩ 225C 0.087 KΩ
-10C 110.396 KΩ 110C 1.030 KΩ 230C 0.080 KΩ
-5C 84.443 KΩ 115C 0.898 KΩ 235C 0.074 KΩ
0C 65.179 KΩ 120C 0.785 KΩ 240C 0.068 KΩ
5C 50.728 KΩ 125C 0.688 KΩ 245C 0.063 KΩ
10C 39.786 KΩ 130C 0.606 KΩ 250C 0.058 KΩ
15C 31.427 KΩ 135C 0.534 KΩ
20C 24.991 KΩ 140C 0.473 KΩ
25C 20.000 KΩ 145C 0.420 KΩ
30C 16.104 KΩ 150C 0.373 KΩ
35C 13.044 KΩ 155C 0.334 KΩ
40C 10.627 KΩ 160C 0.299 KΩ
45C 8.708 KΩ 165C 0.269 KΩ
50C 7.176 KΩ 170C 0.242 KΩ
55C 5.957 KΩ 175C 0.219 KΩ
60C 4.971 KΩ 180C 0.198 KΩ
65C 4.169 KΩ 185C 0.179 KΩ
70C 3.513 KΩ 190C 0.163 KΩ
75C 2.973 KΩ 195C 0.148 KΩ

Axial Leaded Glass Encapsulated NTC Thermistor Mechanical Test

Test Standard Test Conditions and methods Requirements
Soldering & Solderability IEC60068-2-20
Test Ta
Temperature: 230±5 ℃,
2-2.5mm away from ceramic body
On: 2±0.5 Seconds.
The terminations shall be evenly tinned
Resistant to soldering heat IEC60068-2-20
Test Tb
Temperature: 260±5℃,
2-2.5mm away from ceramic body
On:10±1 Seconds.
No visible damage,
Lead wire tensile IEC60068-2-21
Test U
Test Ua: Force 10N, On 10 Seconds;
Test Ub: Bending 90C, Force 5N, Twice.
No break off,

Axial Leaded Glass Encapsulated NTC Thermistor Reliability Data

Test Standard Test Conditions ΔR25/R25 (typical) Remarks
Low temperature storage IEC 60068-2-1 Storage at low category
temperature: -30 oC,
Time: 1000 hours
≤3% No visible damage
Storage in dry heat IEC 60068-2-2 Storage at upper category temperature: 200 oC,
Time: 1000 hours
≤3% No visible damage
Storage in damp heat, steady state (Humidity test) IEC 60068-2-3 Temperature: 40oC,
Humidity:90%-95% RH,
Duration:1000 hours
≤3% No visible damage
Temperature cycling IEC 60068-2-14 1. -30C/30 minutes
2. 80C/5 minutes
3. 200C/30 minutes
4. 80C/5 minutes.
Number of cycles: 5 Cycles
≤3% No visible damage

Axial Lead Glass Sealed NTC Thermistor Application Precaution

Minimum lead wire length tailored to shall be ≥8mm.
In lead wire bending, bending point shall be more than 2mm away from glass body part.

Mounting and Handling Recommendations

Excessive forces applied to a sensor may cause serious damage. To avoid this, the following recommendations should be adhered to:

  • No perpendicular forces must be applied to the body
  • During bending, the leads must be supported
  • Bending close to the body must be done very carefully
  • Axial forces to the body can influence the accuracy of the sensor and should be avoided
  • These sensors can be mounted on a minimum pitch of >5 mm

Soldering and Welding

  • Avoid any force on the body or leads during, or just after, soldering.
  • Do not correct the position of an already soldered sensor by pushing, pulling or twisting the body.
  • Prevent fast cooling after soldering.
  • For hand soldering, where mounting is not on a printed-circuit board, the soldering temperature should be <300C the soldering time <3 s and the distance between body and soldering point >1.5 mm.
  • For hand soldering, dip, wave or other bath soldering, mounted on a printed-circuit board, the
  • soldering temperature should be <300C, the soldering time <5 s and the distance between body and soldering point >1.5 mm.
  • The distance between the body and the welding point should be >0.5 mm. Care should be taken to ensure that welding current never passes through the sensor. 

Other Related AMWEI NTC Thermistors Products for Temperature Sensing