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1 J. of the Korean Sensors Society Vol. 18, No. 1 (009) pp. 8 3 VO w PCM yá Á Á Ÿ Built-in protection circuit module by using VO temperature sensors K. H. Song, J. B. Choi, M. W. Son, and K. S. Yoo Abstract Most portable mobile devices employ rechargeable lithium-ion batteries. This lithium-ion battery usually suffers from the possibility of explosion due to heat generation from surrounding atmosphere or internal deficiency during charging or at overuse. To solve these problems, most rechargeable batteries have a built-in protection circuit module (PCM). The resistance of a properly processed VO critical temperature sensor (CTS) is changed dramatically at a critical temperature of around 68 o C, which can replace some bi-metal, NTC, or PTC sensors embedded in PCM. Such VO CTS consumes a very small current at the level of natural discharge. Experimental results showed that this CTS could be applied to a PCM as the PCM could protect the battery while keeping its power consumption at minimum. Key Words : vanadium oxide, critical temperature sensor, protection circuit module 1. ƒ w j MIT(Metal-insulator transi- ú y»» IT w tion) p ùkü. w w s, p, mp3, le, PMP { Ÿw,» y ùkü ƒ þƒ»»ƒ w.»» p l w. ù p hysteresis p ùkü. p» w 10 ~10 5 order w l w»» w w w y CTR(Critical temperature l ü ƒ w š resistor) š w. CTR z ùkü t. w l ƒ s w x y ù [1]. j» w. w l s w» w Vanadium-Oxygen system w PCM(Protection circuit module) w PCM w y VO, VO, V O 3, V 3 O 5, V O 5 ƒ w. PCM w V 3 O 5 VO V n O n 1 (4 n 8) Magneli k, NTC, PTC w wš w ƒ š PTCƒ š.. VO 68 o C» (sensing mech- yw anism)ƒ VO, VO, TiO,. V-O- Fe O 3, NbO, NiO 3 y V w œ w w w». y, w w œw (Department of Materials Science and Engineering, University of Seoul) Corresponding author: [email protected] (Received : October 1, 008, Revised : December 0, 008 Accepted : December 7, 008) š. y VO 68 o C w ƒ ƒ ƒw 68 o C w ƒ w x []. ù y w w ƒ - w p ( w jumping j») w, ù y /z y 8

2 VO w PCM 9 t š [3,4]. p l š PTC, PCM t CTR VO z wš NMOS Field Effect Transistor(NMOSFET) w l ü»» z w p d sƒw.. x š V O 5 (99.6 %, Aldrich) w, High Energy Ball-milling (FRITSCH, Planetary mill P-6) w w q vehicle(56 wt% a-terpinel, 7 wt% - butoxy ethoxy, 11.5 wt% polyvinyl butyral-co-vinyl alcohol-co-vinyl acetate, 16.5 wt% polyethylene glycol) wì 1 : 0.65 (q : vehicle) Shaker (FINEPCR, Vortex mixer) w 1 y ww r p(paste)y w. yw r p silk-screen printing ù»q z x. w» w w Fig. ùkü, (a) ù» œ 60 o C 10 w z q y ù z s k, (b) N» 500 o C, 1 w [5,6]. p ƒ w š, (c) w ƒ w VO NMOSFETƒ y. œ» (annealing tube furnace) w. y» w z y VO x. V O 5 VO y V O 5 V 3 O 7 V 4 O 9 V 6 O o C¾ 3 o C/min w. p 55 o C~75 o C 0.1 o C/ Fig. 1. VO sensor resistance and NMOS gate voltage according to the temperature change. jumping j»)ƒ 10 4 order d ew y w [5,8]., VO z NMOSFET y Fig. 3 VO w y z ùkü. w 68 o C w R1 VO ƒ w(r1 = 3 MΩ) w NMOSFETƒ OFF VO y ù š [7]. l p(v g ) VO 1. µa» p» w - w p ƒ l V g ƒ d w. yw d w. 68 o C Climatic Chamber(Vötsch, VC 4018) w 5 ~ R1 VO ƒ û w(r1 = 300 Ω) w VO 1 ma ƒ NMOSFETƒ ON š l V d w w min - w p V d l s l»» yw» d w. w., 68 o C d NMOSFET w NMOSFET p 0.4 Vƒ š, one chipy w, y NMOSFET 68 o C p 0.4 V e y w. NMOSFETƒ. 3. š Fig. 4 VO NMOSFETƒ y p [Fig. (4a)] p [Fig. (4b)] Fig. 1 VO - w w. p NMOSFET p ùkü w NMOSFET - (I-V) p VO. wp 5 o C 80 o C w r ( w w y p k w š, 9 J. Kor. Sensors Soc., Vol. 18, No. 1, 009

3 송건화 최정범 손명우 유광수 30 Fig. 3. Power-off protection circuit module using VO temperature sensors. Fig.. (a) VO temperature sensor, (b) Temperature sensor combined with semiconductor device, (c) Semiconductor-type temperature sensor integrated the VO thick film and MOS transistor. 단일 NMOSFET의 소자특성과 비교 되었다. 온도센서 의 등가회로 구성은 Fig. 3과 같다. Fig. 4(a)는 드레인 전압이 0.05 V와 1 V에서 수행된 게이트 전압 변화에 따른 드레인 전류 특성변화(I -V )의 시뮬레이션 결과 이다. VO 센서가 1.5 MΩ 이상의 높은 저항을 갖는 상전이 온도 이하에서는 NMOSFET의 게이트 전극에 Fig. 4. (a) Gate voltage vs. drain current, (b) Drain voltage 문턱전압(threshold voltage)인 0.08 V 이상의 전압이 vs. drain current. 인가되지 않기 때문에 소자가 구동되지 않는다. 상전이 온도 이상에서는 VO 센서의 저항이 300 Ω 이하로 급 이상의 전압이 인가된다. 또한 증가하는 게이트 전극 격히 감소하기 때문에 게이트 전극에 문턱전압 0.08 V 전압에 따라서 드레인 전류의 증가를 확인 할 수 있다. D G 센서학회지 제 권 제 호 18 1,

4 VO w PCM 31 VO w y NMOSFET ƒ on/off w e p y w. Fig. 4(b) NMOSFET p p (I D -V D ) y ùküš. l l 0. V p ƒ j ww. w VO ƒ w ƒ ƒw y w. VO w y w NMOSFET p w ƒ w y w ù, 10 4 A w p y w. VO NMOSFETƒ y e w p ƒ d w š, PCM ƒ y w. 4. VO V O 5 z w y w z PCM w y VO NMOSFET p, z w xw p l PCM l ü y w w w s ƒ p w. š x [1] C. H. Griffiths and H. K. Eastwood, Influence of stoichiometry on the metal-semiconductor transition in vanadium dioxide, J. Appl. Phys., vol. 45, no. 5, pp , [] K. S. Yoo, J. M. Kim, and H. J. Jung, Electrical properties of semiconducting VO -based critical temperature sensors, J. Kor. Ceram. Soc., vol. 30, no. 10, pp , [3] Y. Muraoka, Y. Ueda, and Z. Hiroi, Large modification of the metal-insulator transition temperature in strained VO films grown TiO substrates, J. Phys and Chem. of Solids, vol. 63, pp , 00. [4] Y. Ningyi, L. Jinhua, and L. Chenglu, Valence reduction process from sol-gel V O 5 to VO thin films, Appl. Surf. Sci., vol. 191, pp , 00. [5] K. H. Song and K. S. Yoo, Characterization of VO thick-film critical temperature sensors by heat treatment conditions, J. Kor. Sensors Soc., vol. 16, no. 6, pp , 007. [6] Dachuan, Niankan, Jingyu, and Xiulin, High quality vanadium dioxide films prepared by an inorganic sol-gel method, Materials Research Bulletin, vol. 31, no. 3, pp , [7] J. H. Kang, H. B. Shim, S. H. Park, K. H. Song, and K. S. Yoo, Temperature vs. resistance properties of the VO -based critical temperature sensors, Proceedings of the International Sensors Conference. pp , 004. [8] J. Verkelis, Z. Bliznikas, K. Breive, V. Dikinis, and R. Sarmaitis, Vanadium oxides thin films and fixed-temperature heat sensor with memory, Sensors and Actuators A, vol. 68, pp , y( ) w œw 1991 w w (œw ) 005 ~ x w w 1984 ~ 000 ( ) VCR 000 ~ 00» ( ) 00 ~ x p p t :, d l ( Ž) w œw ~ x w w 31 J. Kor. Sensors Soc., Vol. 18, No. 1, 009

5 3 yá Á Á Ÿ ( ) w œw ~ x w w Ÿ (œ ) w w» œw 1983 w» œw (œw ) ù w œ w (œw ) 1983 ~ 1984 x ( ) 1984 ~ 1987 w w»» 1991 ~ 1995 w w» 1995 ~ x w œ w 1998 ~ x w wz r,,,, («) 00 ~ x w wz w, r, («) z 005 ~ 007 w» 007 ~ x w œ w w / w 007 ~ x w œ w x z z :,,, wz 18«1y, 009 3