THERMISTOR Thermally Sensitive Resistor. NTC CHARACTERISTIC PRODUCT EXAMPLES APPLICATIONS

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1 ISC, UNPAD Oct 2008 Synthesis and Characterization of CuFe 2 O 4 Thick Film Ceramics for NTC Thermistor Using Yarosite as Raw Material Wiendartun 1 ),, Dani Gustaman Syarif 2 ) 1 ) Department of Physics, UPI, Bandung 2 )Nuclear Technology Center for Materials and Radiometry BATAN, Bandung.

2 INTRODUCTION THERMISTOR Thermally Sensitive Resistor. NTC CHARACTERISTIC PRODUCT EXAMPLES APPLICATIONS R vs T- THERMISTOR Current limiter thermistor Incubator Specialize Thermistor Computer

3 INTRODUCTION (Continuation) Important electronic component. - Sectors: Biomedical, aerospace, instrumentation, communications, automotive and HVACR (Heating, Ventilation, Air conditioning and Refrigeration). -Application : Temperature sensor measurement, current limiter, circuit compensation, suppression of in rush- current, flow rate sensor and pressure sensor. It is necessary to get capability in self producing thermistor by utilizing material abundant in Indonesia such us yarosite mineral (Fe 2 O 3 ) CuFe 2 O 4 based-thick film for NTC Thermistor. The thermistor in the form of thick film is possible for miniaturization and integration. Advantages : more practical, profitable economically, need a few material, and fired at law temperature.

4 YAROSITE MNERAL Hibah BERSAING, 13 Oktober 2008

5 EXPERIMENT : Powder of Fe 2 O 3 (derived from yarosite mineral) and CuO Crushing Sieving Glass Frit Organic vehicle Mixing Paste Characterization: 1. Electrical 2. XRD 3. Microstructural (SEM) Screen Printing Firing ( C) Electroding Thick Film Ceramics Fabrication of CuFe 2 O 4 thick film ceramics from yarosite mineral ISC - UNPAD, Oct 2008

6 SCREEN PRINTING Screen screen stress Squeeze Coated Film snap-off distance Paste Substrate Hibah BERSAING, 13 Oktober 2008

7 Electrical Characteristic R = R 0. Exp.(B/T) Ln R = B/T + Ln Ro Ea = B.k α = - B/T 2 R = Thermistor resistance R o = Resistance at the infinite temperature B = Thermistor constant T = Temperature of thermistor in Kelvin Ea = Activation energy K = The Boltzmann constant Α = Sensitivity of thermistor

8 RESULT : Chemical composition of Fe 2 O 3 powder derived from yarosite table No. Component Concentration (Weight %) 1 Fe 2 O Al 2 O SiO TiO MgO K 2 O CaO Na 2 O MnO 0.09

9 RESULT Thick Film ( yarosite) Visual appearance Alumina Substrat Thick film before fired Thick film fired at 1100 C/1 hr ISC -UNPAD, Oktober 2008

10 A typical thick film thermistor Sensor Layer Silver Electrodes

11 RESULT (XRD) Fired at 900 o C Fired at 1000 o C Fired at 1100 o C XRD profile of CuFe 2 O 4 based-thick film

12 RESULTS (Microstructure) Fired at 900 o C Fired at 1000 o C Fired at 1100 o C Microstructure of the CuFe 2 O 4 thick film

13 RESULTS (Electrical Characteristics) ln R(Mohm m) /T(1/K) 900 o C 1000 o C 1100 o C Ln resistivity ( ) vs 1/T of CuFe 2 O 4 thick film ceramics.

14 RESULTS (Electrical Characteristics) Table of electrical characteristics of CuFe 2 O 4 thick film ceramics. No. Firing B R RT Ea Temperature ( o K) (%/ o K) (M.Ohm) (ev) ( o C) Market requirement for : B is 2000 o K is 2.2 %/ o K[7] RT = 10 ohm.cm -1 Mohm.cm [4].

15 CONCLUSIONS CuFe 2 O 4 thick film ceramics utilizing Fe 2 O 3 derived from yarosite mineral have been well prepared at 900 o C, 1000 o C and 1100 o C. All of the thick films crystallize in tetragonal spinel. The increase of firing temperature till 1000 o C decreases the resistance and thermistor constant of the thick films, however, a further increase to 1100 o C increases the resistance and thermistor constant of them. So, 1000 o C is the optimum firing temperature for preparing the thick films in this work. The thick film fired at 1000 o C has optimal characteristic namely thermistor constant (B) = 3150K and room temperature resistance (R RT ) = 7.9 MOhm. These values fit the market requirement for NTC thermistor.

16 THANK YOU ACKNOWLEGMENT The authors wish to acknowledge their deep gratitude to DIKTI, Department of National Education of Indonesian Government for financial support under HIBAH BERSAING program with contract No.014/SP2H/PP/DP2M/III/ M/III/2008

17 LAMPIRAN APLIKASI THERMISTOR-1 Inkubator Bayi

18 APLIKASI THERMISTOR-2 Komputer

19 APLIKASI THERMISTOR-3 Pengukur suhu

20 APLIKASI THERMISTOR-4 Sensor Aliran Air

21 APLIKASI THERMISTOR- 5 Lampu neon Thermistor AC Pembatas Arus Listrik

22 BENTUK THERMISTOR-1 Thermistor Pembatas Arus

23 BENTUK THERMISTOR-2 Thermistor Gelas

24 BENTUK THERMISTOR-3 Thermistor Khusus

25 BENTUK THERMISTOR-4 Thermistor Lead Epoxy