Commercializing "Thermo-String" a Small, High-Precision and Flexible Lead Thermistor for Temperature Sensing

Thermo-String

10/5/2009

Murata Manufacturing Co., Ltd.

President/ Statutory Representative Director: Tsuneo Murata

Overview

Murata Manufacturing Co., Ltd. has commercialized “Thermo-String,” a small, high-precision temperature-sensing device utilizing Chip POSISTOR® or a chip NTC thermistor as the detector element. This “Thermo-String” allows for temperature sensing in a tight space due to its ultra small sensing device at less than 1.6 x 0.8 [mm] and coated lead wire with flexible length between 25mm and 150mm. A Chip NTC thermistor used at the detector element enables a lineup with an extensive range of resistance and B-values*.

While an NTC thermistor is generally used at the sensing device, Murata’s overheat detection chip PTC or POSISTOR® may be used in its place simplifying the temperature sensing circuit.

*B-value: A constant representing the variance in resistance corresponding with the temperature

Background

Temperature control becomes more vital as electric equipment become smaller and more densely mounted. Use of lithium-ion rechargeable batteries is increasing becoming more common not only for note-size PCs, but also electric tools and HEVs, creating stronger demands for overheat detection of their battery cells. NTC thermistors, with their varying resistance according to the temperature change, are widely used for temperature sensing of electronic equipment, allowing “Thermo-String” to accommodate a wide range of temperature sensing demands that are now becoming ever stronger. Also, utilizing characteristics of Murata’s PTC thermistor or POSISTOR®, where the resistance value rapidly increases above a certain temperature, allows for more simplified temperature sensing circuit.

Features

  • Introducing chip NTC thermistor as the temperature sensing device, offering a wide variation in resistance values and B-values
  • Realizing much smaller sensing device (diameter at the tip) at less than 1.6mm
  • Introducing flexible coated lead wire, allowing for wiring in very tight areas within electronic equipment
  • Accommodating lead wire length between 25mm and 150mm
  • Use of a chip PTC POSISTOR® for overheat detection is optional
  • Halogen-free (except for some models)

Part Number

Series Part Number Sensing temperature
NTC lead
For general consumer market
NXFT15*** -40℃~125℃
NTC lead
For automobile electrification
NXFS15*** -40℃~150℃
PTC lead
For general consumer market
PXFT15*** 55℃~130℃
-40℃~140℃
(operating temperature)
PTC lead
For automobile electrification
PXFS15*** (Under development) 55℃~130℃
-40℃~150℃
(operating temperature)

External Size

External Size
  Dimensions (mm) notes
D 1.2±0.4 Resin width
T 1.2±0.4 Resin width
L 25~100±2
110~150±3
Full length
L1 3+2/-1 Soldering part
d 0.30±0.05 Lead wire Diameter

Production

300 thousand units per month in August 2009

Sample Price

20 Yen (or about $0.23 at 90 yen /dollar) /per unit (NXFT series)
Varies depending on the specification and the amount.


Murata in Brief

Murata Manufacturing Co., Ltd. is a worldwide leader in the design, manufacture and sale of ceramic-based passive electronic components & solutions, communication modules and power supply modules. Murata is committed to the development of advanced electronic materials and leading edge, multi-functional, high-density modules. The company has employees and manufacturing facilities throughout the world. For more information, visit Murata's website at www.murata.com