Research of the High Voltage Etching Fuse for Protecting Semiconductors

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1 Extended Summary pp Research of the High Voltage Etching Fuse for Protecting Semiconductors Mitsuo Asayama Student Member (Saitama University, Yuhzoh Ishikawa Member (Saitama University, Kengo Hirose Member (Saitama University, Shinichi Kobayashi Member (Saitama University, Yasushi Yamano Member (Saitama University, Keywords: fuse, etching fuse, semiconductor protection Recently uses of high voltage power electronics equipments have increased, so that high voltage current limiting fuses having excellent performance for semiconductor protection is required. We made trial products of etching fuse for protecting semiconductors experimentally and made various tests to confirm their performance. In addition we investigated the performance required to the high voltage fuse for protecting semiconductors. Results are as follows. ( 1 ) Investigation of the performance required to the high voltage fuse for protecting semiconductors. At present IGBTs or IPMs are mainly used as a semiconductor device for power electronics equipments such as inverters, but because of small heat capacity of their junction it is impossible to protect devices against over current failure by fuses. Nevertheless many fuses are still used for protection against the explosion of IGBT cases caused by the high fault current. Now there is no specified national standard and IEC standard related high voltage fuse for protecting semiconductors, therefore we have to confirn the general characteristics of high voltage fuse in accordance with JEM standard for the low-voltage fuses for the protection of semiconductor device. Moreover we investigated that the fuse apllied to inverters had to have special performances in addition to general characteristics, which we pointed out next 3 items. ( i ) Possibility of endurance against maximum voltage occurred after current interruption. It will be 110% of the rated voltage (8 kv in case of 7.2 kv rated voltage fuse). ( ii ) Possibility of breaking performance of the high di/dt value current discharged from the smoothing capacitor in the inverter circuit. (iii) Mechanical strength against fatigue by thermal expansion and shrinking due to repitation of current flow. ( 2 ) Feature of the etching fuse The etching fuse consists of an etched copper element plated on a thin ceramic substrate. This type of fuse has following features. ( i ) Excellent current breaking performance can be achieved, since the elaborate fuse element can be made. ( ii ) The element is mechanically strong and thus durable, since it sticks firmly to the ceramic substrate, therefore fatigue by thermal expansion and shrinking due to repitation of current flow does not appear. From these points an etching fuse makes it possible to realize a high voltage fuse for protecting semiconductor. We made trial products of etching fuse as shown in Table 1 with target rating. Elements pattern, the number of series current breaking points, and parallel current breaking points were decided on the basis of the research of the low voltage etching fuse for protecting semiconductors, to achieve the most desirable value. Fig. 1. Table 1. Target rating of a trial products Current breaking test result data and oscillogram ( 3 ) Test results of etching fuses ( i ) Current breaking test at rated voltage Current breaking test at commercial frequency was carried out at LC current breaking test circuit. Test result data and oscillogram were shown in Fig. 1. It shows excellent current breaking performance and small operating I 2 t value compered with the target value. ( ii ) Current breaking test at higher voltage circuit Current breaking test was carried out in circuit at higher voltage of 110% of the rated voltage (8 kv), and capability of breaking the short circuit current at this voltage was proved. (iii) Current breaking test of high di/dt value current discharged from smoothing capacitor in inverter circuit. This test was carried out by breaking the discharge current from 4.0 mf capacitor, and it was found that an etching fuse was able to break with low cut-off current and short operating time. (iv) Endurance test by repetitive current flow This test was carried out by repetitive rated current flows of 400 cycles in the cycle of 1 hour flow and 1 hour rest, and test result showed that nothing was wrong such as fusion and over heat. The result of these tests shows that the etching fuse has possibility to realize a high voltage fuse for protecting semiconductor. 8

2 Research of the High Voltage Etching Fuse for Protecting Semiconductors Mitsuo Asayama, Student Member, Yuhzoh Ishikawa, Member, Kengo Hirose,Member, Shinichi Kobayashi, Member, Yasushi Yamano,Member This paper describes the high voltage etching fuse for protecting semiconductors. At first the performance required to the fuse was investigated. Then test results of trial products of 7.2 kv rating etching fuses were shown. At present the specified national standard for high voltage fuse for semiconductor protection has not been established. Therefore, firstly we confirmed the general characteristics of high voltage fuses in accordance with JEM standard for the low-voltage fuses for the protection of semiconductor device. Next we investgated the breaking performance on the basis of the following 3 items, since the fuse applied to inverters must have special performances in addition to general characteristics. (a) Possibility of endurance against maximum voltage occurring after current interruption, (b) Possibility of breaking current having the high di/dt value due to being discharged from smoothing capacitor in inverter circuit, and (c) Mechanical strength against fatigue by thermal expansion and shrinking due to repetition of high current flow. It was found that an etching fuse have higher current breaking performance and mechanical strength. Current breaking test results exhibited that a 7.2 kv, 100 A rating fuse had small operating I 2 t value, that is excellent current breaking performance, and cleared above three points. Keywords: fuse, etching fuse, semiconductor protection 1. (1) IGBT IPM Saitama University 255, Shimookubo, Sakura-ku, Saitama GTO IGBT IGBT IGBT GTO I 2 t (a) 666 IEEJ Trans. PE, Vol.127, No.5, 2007

3 (b) di/dt (c) JEM1383 JEM1293 IEC JEM1383 JEM1293 JISC L 0 (2) (3) IEC IEC269-4 (4) 110% AC 7.2 kv AC 8 kv RMS ,000 V 2(a) 1 2(b) R 1 L 1 3 EMTP (5) 2(b) di/dt A/s 40 ka 40 ka 2(b) C 2 C 4 3 C 1 3 di/dt L I 2 t (a) An example of circuit of smoothing capacitor (b) Equivalent circuit of (a) 1 Fig. 1. Applied circuit of the fuse. 2 Fig. 2. Circuit of smoothing capacitor. B

4 1 Table 1. Target rating of trial product. Fig Simplified equivalent circuit of Fig. 2(b). 24 mm 280 mm 5 Fig. 5. Outline of fuse element. (1) Wave form of Fig. 3 (2) Wave form of Fig. 2(b) (a) Calculated wave form (3) Wave form of Fig. 3 (4) Wave form of Fig. 2(b) (b) Enlarged time scale wave form 4 Fig. 4. Discharge current wave form JEM1383 JEM IEC JEC % I 2 t I 2 t 6 Fig. 6. Detail of fuse element. I 2 t (1) mm 280 mm 600 V kv 7200/600 = % 280 mm V I 2 t 24 mm IEEJ Trans. PE, Vol.127, No.5, 2007

5 mm 43 mm ,000 µf C L 7.2 kv 40 ka RMS I 2 t % 8.0kV 3 2(b) C 7.2 kv 2.7 kv 2.7 kv Fig. 7. Outside view of fuse link I 2 t 1 8 LC Fig. 8. LC current breaking test circuit. Fig. 10. test. 10 Current breaking oscillogram of rated voltage Table 2. 2 Results of current breaking tests. 9 Fig. 9. Current breaking test circuit of capacitor discharge currrent. B

6 (a) Surface (b) The back 11 Fig. 11. Fuse element after current breaking test. 13 Fig. 13. Current breaking oscillogram of capacitor discharge test % (6) Fig. 12. Current breaking oscillogram of 110% rating voltage test. 11 (a) (b) % 12 di/dt A/s 7,920 V RMS % ,500 A A/s ,000 V I 2 t 18,300 A 2 s % 12 8kV I 2 t µh 670 IEEJ Trans. PE, Vol.127, No.5, 2007

7 IGBT, IPM 3 (a) 7.2 kv 110% 8kV (b) (c) (a) (c) 7.2 kv 100 A 1 I 2 t 2 110% 8kV M. Asayama, Y. Ishikawa, K. Hirose, S. Kobayashi, and Y. Yamano: Improvement of the Etching Fuse Performance by Element Pattern Design, IEEJ Trans. PE, Vol.127, No.3, pp (2007-3), B, 127, 3, pp (2007-3) 2 S. Duong, C. Schaeffer, L. Rouve, J. DePalma, and C. Mullert: Fuse for Power IGBT-Converters, Conf. Rec. IEEE Ind. and Appl. Soc. Annu. Meet., Vol.1994, No.2, pp , USA (1994) 3 S. Duong, C. Schaeffer, F. Sarrus, and C. Mullert: Investigation on fuses against IGBT case explosion, PCIM 1997 Europe (DEU), pp (1997) 4 IEC (Supplementary requirements for fuse-links for the protection of semiconductor devices), IEC Amendment 2 5 EMTP, (2001) 6 H. Takahashi and K. Hirose: A semiconductor fuse-link on a ceramic substrate, The Fourth ICEFA, pp.92 95, UK (1991) 7 S. Duong, J. Schanen, C. Schaeffer, F. Sarrus, and J. DePalma: IGBT protection by fuse calculation, behavior and conection, Conf. Rec. IEEE Ind. Appl. Conf., Vol.1997, No.2, pp , USA (1997) 8 R. Wilkins, H. Cline, and E. Knapp: Fuse protection of IGBT inverters, Off Proc 37th Int. Power Electron Conf., pp , USA (1998) B

8 IEEE 672 IEEJ Trans. PE, Vol.127, No.5, 2007