JP6989372B2 - Circuit separation elements and semiconductor devices - Google Patents

Description

Embodiments relate to circuit separation elements and semiconductor devices.

Power electronics devices such as inverters have a plurality of semiconductor elements built-in and are used for high power control. For example, in applications such as transportation and power transmission and distribution, high reliability is required for power control systems, but if even one of the multiple semiconductor elements that make up these devices fails in a short circuit, the system can continue to operate. become unable. Usually, it is difficult to avoid an accidental short-circuit failure of a semiconductor element, which is a factor that lowers the reliability of the system. Therefore, studies are underway on a system having redundancy that enables continuous operation even if some semiconductor elements fail. However, in such a system, it is difficult to avoid the increase in size and cost due to the arrangement of spare equipment.

Japanese Unexamined Patent Publication No. 2011-199940 Japanese Unexamined Patent Publication No. 2013-38864 Japanese Unexamined Patent Publication No. 2014-236580 Patent No. 5489586

The embodiment provides a circuit separation element and a semiconductor device that separate a failed semiconductor element from a circuit and enable continuous operation of the entire system.

The circuit separation element according to the embodiment includes an insulator, a first electrode provided on the insulator, a second electrode provided on the insulator at a position separated from the first electrode, and the insulation. A plurality of linear conductors provided on the body and connected to the first electrode and the second electrode are provided. The number of the linear conductors is larger than the value obtained by dividing the maximum current value flowing between the first electrode and the second electrode by the minimum arc current value of the linear conductors.

Further, the semiconductor device according to the embodiment includes a semiconductor element and a circuit separation element connected in series to the semiconductor element. The circuit separation element is on the insulator, the first electrode provided on the insulator, the second electrode provided on the insulator at a position separated from the first electrode, and the insulator. The maximum rated current of the semiconductor device includes a plurality of linear conductors provided and connected to the first electrode and the second electrode, respectively, and the maximum rated current of the semiconductor device is the number of the linear conductors and the minimum of the linear conductors. It is smaller than the value multiplied by the arc current value.

It is a perspective view which shows typically the circuit separation element which concerns on embodiment. It is a schematic diagram which shows the circuit separation element which concerns on embodiment. It is a schematic diagram which shows the characteristic of the circuit separation element which concerns on embodiment. It is a graph which shows the characteristic of the circuit separation element which concerns on embodiment. It is a schematic diagram which shows the semiconductor device which concerns on embodiment. It is a schematic diagram which shows the operation of the semiconductor device which concerns on embodiment. It is a circuit diagram which shows the semiconductor device which concerns on embodiment. It is a schematic diagram which shows the circuit separation element and the test circuit which concerns on embodiment. It is a schematic diagram which illustrates the voltage waveform and the current waveform measured by the test circuit which concerns on embodiment. It is a schematic diagram which shows the test result of the circuit separation element which concerns on embodiment. It is a schematic diagram which shows the other test result of the circuit separation element which concerns on embodiment.

Hereinafter, embodiments will be described with reference to the drawings. The same parts in the drawings are designated by the same number, detailed description thereof will be omitted as appropriate, and different parts will be described. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the ratio of the sizes between the parts, and the like are not necessarily the same as the actual ones. Further, even when the same part is represented, the dimensions and ratios may be different from each other depending on the drawing.

Further, the arrangement and configuration of each part will be described using the X-axis, Y-axis and Z-axis shown in each figure. The X-axis, Y-axis, and Z-axis are orthogonal to each other and represent the X-direction, the Y-direction, and the Z-direction, respectively. Further, the Z direction may be described as upward, and the opposite direction may be described as downward.

FIG. 1 is a perspective view schematically showing the circuit separation element 1 according to the embodiment. The circuit separation element 1 includes, for example, an insulating substrate 10, electrodes 20, 30 and a plurality of linear conductors 40. The electrodes 20 and 30 and the linear conductor 40 are provided on _{the upper surface 10 T of the insulating substrate 10.}

As shown in FIG. 1, the electrode 20 is arranged at a position separated from the electrode 30 in the X direction. The linear conductor 40 extends in the X direction, respectively, and is connected to the electrode 20 and the electrode 30. The linear conductor 40 contains, for example, the same materials as the electrodes 20 and 30. That is, the linear conductor 40 is provided integrally with the electrodes 20 and 30. Further, the linear conductor 40 may contain a material different from that of the electrodes 20 and 30.

As the material of the insulating substrate 10, any material can be used as long as it has insulating properties, regardless of whether it is an organic material or an inorganic material. The insulating substrate 10 preferably contains, for example, at least one of glass and ceramics, which are highly heat-resistant insulating materials. Further, an epoxy resin, a phenol resin, a fluororesin, a polyimide, or the like may be used for the insulating substrate 10, and insulation between them and insulating filler particles such as silica, alumina, and aluminum nitride, or insulation such as glass fiber. A material in which sex fibers are combined may be used.

For the electrodes 20 and 30, for example, a metal material capable of wire bonding or solder bonding is used. For the linear conductor 40, for example, any one of copper and a copper alloy, aluminum and an aluminum alloy, tin, zinc, bismuth, and nickel is preferably used, but the linear conductor 40 is not limited thereto. Further, it is preferable to use a metal whose oxide has an insulating property for the linear conductor 40. That is, when the linear conductor 40 is melted in an atmosphere containing oxygen, it is preferable that an insulating oxide is formed on the surface thereof. As a result, the electrical resistance of the fused (separated) linear conductor 40 is remarkably increased, so that the circuit separation speed can be improved and the insulation reliability after separation can be ensured. Further, a material for improving adhesion such as titanium (Ti), chromium (Cr), tantalum (Ta), tungsten (W) and a compound containing these is interposed between the insulating substrate 10 and the linear conductor 40. You may let me.

The electrodes 20 and 30 and the linear conductor 40 can be formed by using, for example, a printing method using a mask such as squeegee printing, or a maskless printing method such as inkjet, bubble jet (registered trademark), or imprint. .. It can also be formed using thin film forming methods such as plating, sputtering, vacuum deposition, ion plating, and photolithography.

2 (a) and 2 (b) are schematic views showing the circuit separation element 1 according to the embodiment. FIG. 2A is a plan view showing the upper surface of the insulating substrate 10, and FIG. 2B is a cross-sectional view taken along the line 2B-2B shown in FIG. 2A. The electrodes 20 and 30 and the linear conductor 40 shown in FIGS. 2A and 2B are examples, and the embodiment is not limited thereto.

As shown in FIG. 2A, the linear conductor 40 extends in the X direction and has a length L. Also, the linear conductor 40 has a width _{W M} of Y-direction. Linear conductor 40 is provided, for example, a line shape extending in the X direction, a L»W _M. Linear conductor 40 is, for example, are arranged in the Y direction with an interval W _S.

As shown in FIG. 2 (b), the linear conductor 40 has a thickness _{T M} in the Z direction. Further, an insulating film 50 that covers the linear conductor 40 is provided. The insulating film 50 is, for example, a silicon oxide film, a silicon nitride film, or a silicon acid nitride film. The insulating film 50 is formed by, for example, a CVD (Chemical Vapor Deposition) method, a coating method, or a sputtering method. The insulating film 50 has an opening 50 _H located above the electrodes 20 and 30.

In the circuit separation element 1, for example, when a short-circuit current flows between the electrode 20 and the electrode 30 due to a failure of the semiconductor element, the linear conductor 40 is melted by the Joule heat, and the linear conductor 40 is melted between the electrode 20 and the electrode 30. It works by breaking the electrical connection.

FIG. 3 is a schematic diagram showing the modeled characteristics of the circuit separation element 1. For example, let N be the number of parallel conductors 40 in parallel, and let i be the current flowing between the electrodes 20 and 30. That is, it is assumed that an i / N current flows through each of the linear conductors 40.

As shown in FIG. 3, the current i between the electrode 20 and the electrode 30 and the calorific value Q of the linear conductor 40 are generated in steps at time t = 0 and are constant with respect to time t. In this case, the resistance of the linear conductor 40 uses a predetermined temperature value and is constant regardless of the temperature T. For example, when copper is used as a material, a resistance value of T = 1000 ° C. is used.

ここで、Ｑ_Ｔ（＝Ｑ×ｔ）は累積発熱量、Ｃは熱容量、ｒは比抵抗、ρは密度、ｃは比熱である。また、断面積Ｓは、複数の線状導体４０の全断面積であり、Ｓ＝Ｗ_Ｍ×Ｔ_Ｍ×Ｎである。 Temperature variation ΔT of the linear conductor 40 (= _{T-T R)} is calculated using the following equation (1), increases from room temperature _{T R} linearly with time t.

Here, Q _T (= Q × t) is the cumulative calorific value, C is the heat capacity, r is the specific resistance, ρ is the density, and c is the specific heat. Further, the sectional area S is the total cross-sectional area of the plurality of linear conductors 40, which is _{S = W M × T M ×} N.

As shown in the equation (1), the temperature change amount ΔT of the linear conductor 40 is expressed as a function with the current i and the time t as variables, and is expressed in the specific resistance r, the density ρ, the specific heat c, and the cross-sectional area S of the material. Dependent. Here, the length L of the linear conductor 40 is canceled in the equation. Therefore, ideally, if the material constituting the linear conductor 40 is specified, it can be seen that the cross-sectional area S becomes a parameter for increasing the temperature. When the cross-sectional area of the linear conductor 40 changes in the direction in which the current flows, the cross-sectional area S similar to that of a rectangular parallelepiped is used.

ここで、ｔ＝ｔｒ、ΔＴ＝Ｔｍ−Ｔ_Ｒとして、線状導体４０の断面積Ｓの上限を求めることができる。Ｔｍは、線状導体４０の融点であり、ｔｒは、線状導体４０の温度が融点に達するまでの時間である。 Further, the cross-sectional area (S / i) per unit current is expressed by the following equation (2).

Here, t = tr, as ΔT = _{Tm-T R,} can be determined the upper limit of the cross-sectional area S of the linear conductor 40. Tm is the melting point of the linear conductor 40, and tr is the time until the temperature of the linear conductor 40 reaches the melting point.

The power control system is provided with a protection circuit that detects a short-circuit failure and stops its operation. For example, the time until the protection circuit operates and the power control system is stopped is set to off. By applying the circuit separation element 1 to the power control system and setting tr <toff, for example, the failed semiconductor element can be separated from the circuit before the power control system is stopped. As a result, even if the semiconductor element connected to the circuit separation element 1 fails, the operation of the power control system can be continued.

For example, when the material of the linear conductors 40 is a copper or copper alloy, tr = 10μsec, Tm = 1085 ℃, it is calculated as T R = 25 ° C., the cross-sectional area S per unit current, 14 × ¹⁰ -6 mm It becomes ^{2 / A.} That is, when a current of 1 A ^{flows through the linear conductor 40 having a cross-sectional area of 14 × 10 -6} mm ² , the temperature reaches the melting point of copper 1085 ° C. in 10 μsec after the short-circuit current starts to flow.

線状導体４０の並列数Ｎは、Ｓｍａｘを線状導体４０のそれぞれの断面積（Ｗ_Ｍ×Ｔ_Ｍ）で除した値と同じか、それよりも小さい。ここで、最大電流Ｉｍａｘは、例えば、線状導体４０を溶断する電流値である。 Assuming that the maximum current flowing between the electrode 20 and the electrode 30 is Imax, the maximum value Smax of the cross-sectional area S for fusing the linear conductor 40 within the time tr is expressed by the equation (3).

Number of parallel linear conductors 40 N is equal to the value obtained by dividing the respective cross-sectional area _{(W M} × _{T M)} of the linear conductor 40 to Smax, smaller than that. Here, the maximum current Imax is, for example, a current value that blows the linear conductor 40.

On the other hand, when the linear conductor 40 is blown, if the current flowing through each of the linear conductors 40 is large, the arc discharge is sustained at the blown portion. Therefore, the electrical connection between the electrode 20 and the electrode 30 is not completely separated, and the system may be stopped.

There are research examples (reference: Paul G. Slade, "ELECTRICAL CONTACTS (PRINCIPLES AND APPLICATIONS)", 2nd Edition, CRC Press, 2014) on the generation and persistence of arcs when separating circuits. For example, each linear conductor It is known that when the current of 40 exceeds the minimum arc current value, the arc discharge is sustained. The minimum arc current value is an eigenvalue for each material. For example, the minimum arc current value of aluminum is 0.4 A, and the minimum arc current value of tungsten is 1.0 A.

It should be noted that these research examples are the results of electrical contacts and disclose one index. That is, it relates to an arc current generated when the contacts of a pair of metal members are separated from each other. It is considered that an arc discharge similar to that of an electric contact occurs at the end portion of the linear conductor after separation in the present embodiment, and there is a current threshold that does not sustain it, that is, a minimum arc current value. However, it should be noted that the threshold does not necessarily coincide with the minimum arc current at the electrical contact.

例えば、半導体装置やインバータにおける短絡電流は、概ね1００Ａ〜２０００Ａである。したがって、線状導体４０の材料をアルミニウムとすれば、その並列数Ｎは、２５０〜５０００である。また、線状導体４０の材料をタングステンとすれば、並列数Ｎは、１００〜２０００となる。 The current flowing through each linear conductor 40 is preferably smaller than the minimum arc current value. That is, it is desirable to increase the number N of parallel conductors 40 in parallel and make each current value smaller than the minimum arc current value. For example, the number of parallels N is larger than the maximum current Imax divided by the minimum arc current value Iarc_min. As a result, the parallel number N of the linear conductors 40 is preferably within the range shown in the equation (4).

For example, the short-circuit current in a semiconductor device or an inverter is approximately 100A to 2000A. Therefore, if the material of the linear conductor 40 is aluminum, the parallel number N thereof is 250 to 5000. Further, if the material of the linear conductor 40 is tungsten, the parallel number N is 100 to 2000.

Further, the circuit separation element 1 is arranged together with the semiconductor element, for example, in the case of the inverter. Therefore, it is preferable that the size is equal to or smaller than the size of the circuit separation element 1. For example, if the size of the circuit separation element 1 is 15 mm □, which is about the same as that of a semiconductor element, and the short-circuit current is 2000 A, in the case of a linear conductor 40 made of aluminum, the density of the linear conductor 40 in the parallel direction is It becomes 334 lines / mm or more. Further, even if the short-circuit current is 100 A, the density of the linear conductor 40 is 17 lines / mm or more.

Thus, in the linear conductor 40 is arranged at a high density, to optimize the cross-sectional area S, than vary the width W _M of Y-direction, it is preferable to vary the thickness T _M in the Z direction preferable. That is, varying the width W _M of Y-direction, the size in the Y direction of the circuit separation element 1 is increased, there is a case where a circuit isolation device 1 becomes an inhibiting factor in miniaturization.

FIG. 4 is a graph showing the characteristics of the circuit separation element according to the embodiment. The horizontal axis is the thickness T _M of the linear conductor 40, and the vertical axis is a circuit separation time tr. Plot in Fig 3 shows the results of varying the width W _M and the interval W _S of the linear conductor 40 in the range of 0.1 to 3 micrometers ([mu] m).

In this example, the process in which the linear conductor 40 is separated by the short-circuit current is transiently thermally analyzed, and the circuit separation time tr [μsec] is calculated. Indeed, the width _{W M [μm],} and the parameter survey the effects interval _{W S [μm]} and the thickness _{T M [μm]} is given to the circuit separation time tr, obtain the regression equation (5). FIG. 4 is a graph plotting tr calculated using the regression equation (5).

_{tr = 0.53 × W M -0.58 ×} W S + 5.0 × T M +1.5 ··· (5)

For example, in a semiconductor device using an IGBT, the time to off from the detection of the short-circuit current to the operation of the protection circuit is 10 μsec. Therefore, by setting tr <10 μsec, the operation can be continued without stopping the semiconductor device or the power control system.

As shown in FIG. _4, when _{W M = W S = 0.1μm,} tr < the thickness _{T M} is made 10 .mu.sec, for example, or less 2.1 .mu.m. _Further, when _{W M = W S = 3μm,} tr < thickness _{T M} to be 10μsec, for example, it is 1.5μm or less.

In this way, it is possible to reduce the height in the Z direction while suppressing the expansion of the size of the plurality of linear conductors 40 in the X direction and the Y direction. Further, in order to reduce the height of the circuit separation element 1 in the Z direction, the insulating substrate 10 may be thinned. For example, the circuit separation element 1 is mounted in the case of the semiconductor device together with the semiconductor element. Accordingly, the thickness T _M and the insulating circuit height in the Z direction of the separation element 1 including the thickness of the substrate 10 of the linear conductor 40 is, for example, the same as the inner height of the case, preferably lower than .. Further, when the semiconductor element is connected to the substrate wiring via the metal wire, it is desirable that the height of the circuit separation element 1 in the case after mounting is lower than, for example, the looping height of the wire.

5 (a) and 5 (b) are schematic views showing the semiconductor device 100 according to the embodiment. The semiconductor device 100 includes a plurality of semiconductor elements arranged in parallel, for example, n transistors Tr1 to Trn, and is used in an inverter circuit. FIG. 5A is a plane showing the arrangement of transistors Tr1 to Trn. FIG. 5B is a cross-sectional view taken along the line 4B-4B shown in FIG. 5A.

As shown in FIG. 5A, the semiconductor device 100 includes a plurality of wirings 110, wirings 120, and wirings 130. Wiring 120 and 130 extend in the Y direction, respectively. The wiring 110 is arranged side by side in the Y direction between the wiring 120 and the wiring 130. The transistors Tr1 to Trn are connected in parallel to the wirings 120 and 130, and for example, control the on / off of the current flowing between the wirings 120 and the wirings 130. The transistors Tr1 to Trn are mounted on the wiring 110, respectively.

The semiconductor device 100 further includes a plurality of circuit separation elements 1 and a plurality of connecting conductors 140. The circuit separation element 1 is arranged so as to straddle the wiring 110 and the wiring 120, and is connected in series to the transistors Tr1 to Trn, respectively. By arranging the circuit separation elements 1 in the vicinity of the transistors Tr1 to Trn in this way, extra wiring can be omitted and the circuit separation element 1 can be mounted compactly. The connecting conductor 140 is arranged so as to straddle the wiring 110 and the wiring 130, and electrically connects the wiring 110 and the wiring 130.

The wirings 110, 120 and 130 may be, for example, wiring members made by processing a copper foil or an aluminum foil provided on an insulating substrate. Further, the wiring 110, the wiring 120 and 130 may be, for example, lead frames independent of each other. The semiconductor element is, for example, an IGBT or a power MOSFET.

FIG. 5B is a cross-sectional view showing the circuit separation element 1 connected to the wirings 110 and 120. As shown in FIG. 5B, the circuit separation element 1 is _{mounted with the upper surface 10 T} of the insulating substrate 10 facing the wiring 110 and 120 side. The electrode 20 is connected to the wiring 110 via the connecting member 60. The electrode 30 is connected to the wiring 120 via the connecting member 70. As a result, the linear conductor 40 is arranged so as to face the space between the wiring 110 and the wiring 120. The connecting members 60 and 70 include, for example, solder, a conductive adhesive, a diffusion bonding member, a direct metal bonding member, or a sintered bonding member of metal particles.

The above configuration is an example, and the embodiment is not limited to this. For example, a bonding electrode connected to the electrodes 20 and 30 may be arranged on the back surface side of the insulating substrate 10, and the electrodes 20 and 30 and the linear conductor 40 may be mounted upward. Further, the electrodes 20 and 30 may be connected to the wirings 110 and 120 by wire bonding, respectively.

FIG. 6 is a schematic plan view showing the operation of the semiconductor device 100 according to the embodiment. For example, it is assumed that the transistor Tr1, which is one of the transistors Tr1 to Trn, causes a short-circuit failure. When a signal for turning off the transistors Tr1 to Trn is transmitted from a gate circuit (not shown), the normal transistors Tr2 to Trn are turned off, but the transistor Tr1 remains in the short-circuited (ON) state. Therefore, a predetermined voltage is supplied between the wiring 120 and the wiring 130, and a short-circuit current _ISC flows.

For example, if the connection conductor 140 is also arranged between the wiring 110 and the wiring 120 instead of the circuit separation element 1, the short-circuit current I _SC passes through the transistor Tr1 and continues to flow to the wiring 130. Therefore, the protection circuit _{detects the short-circuit current I SC} and stops the inverter including the semiconductor device 100.

In contrast, in the semiconductor device 100, the linear conductor 40 is blown by the short-circuit current I _SC flowing to the circuit isolation device 1 disposed between the wiring 110 and the wiring 120, the short-circuit current I before the protection circuit detects _{The SC} can be blocked. As a result, the transistor Tr1 is separated from the inverter circuit, and the operation of the inverter can be continued by the normal transistors Tr2 to Trn.

For example, if a three-phase inverter circuit is configured by using the semiconductor device 100, a short-circuit current at least three times the maximum rated current Idmax of the semiconductor device 100 flows through the transistor Tr1. When the circuit separation element 1 is applied to such an inverter circuit, the parallel number N of the linear conductors 40 is preferably 3Idmax / Iarc_min or more. The minimum value of the number N of parallel conductors 40 depends on the configuration of the power control system, but at least the maximum rated current Idmax of the semiconductor device 100 is set to the minimum arc current Iarc_min of the linear conductor 40, that is, the linear conductor 40. It is desirable that it is larger than the value divided by the threshold current that can suppress the arc generated after separation.

7 (a) to 7 (c) are circuit diagrams showing a semiconductor device according to an embodiment. 7 (a) and 7 (b) are circuit diagrams illustrating the semiconductor device 100, and FIG. 7 (c) is a circuit diagram showing the semiconductor device 200 according to a modified example of the embodiment.

As shown in FIGS. 7A to 7C, the transistor Tr and the diode FWD are arranged in parallel. The transistor Tr is, for example, a power MOSFET or an IGBT.

The circuit separation element 1 may be connected in series to the drain (collector) side of the transistor Tr as shown in FIG. 7 (a), or may be connected in series to the drain (collector) side of the transistor Tr, or as shown in FIG. 7 (b), the source (emitter) of the transistor Tr. It may be connected in series on the side. In this case, the same number of circuit separation elements 1 as the transistor Tr are arranged inside the semiconductor device 100.

As shown in FIG. 7 (c), the circuit separation element 1 may be arranged on both the source side and the drain side of the transistor Tr. As a result, the transistor Tr is separated from the circuit on both the source side and the drain side. For example, a gate circuit (not shown) is connected to the transistor Tr. Normally, the gate circuit is not designed with high withstand voltage and may be destroyed when a high voltage of the main circuit is applied. Therefore, in addition to the failed transistor Tr, it is preferable to separate the gate circuit connected to the transistor Tr from the main circuit. In the semiconductor device 200, the separation of the gate circuit is also realized by arranging the circuit separation elements 1 on the source side and the drain side of the transistor Tr, respectively.

The circuit arrangements shown in FIGS. 7 (a) to 7 (c) are examples, and the embodiments are not limited thereto. For example, one circuit separation element 1 can be connected in series to a plurality of transistors connected in parallel. As a result, the circuit separation element 1 can be arranged even in a semiconductor device having a small empty space.

[Example]
Hereinafter, embodiments of the present embodiment will be described with reference to FIGS. 8 to 11. Here, an example of measuring the minimum arc current value of a linear conductor made of aluminum, which is one of the metals most easily sustained by arc discharge, will be described.

FIG. 8A is a schematic diagram showing the circuit separation element 2 according to the present embodiment. The circuit separation element 2 includes an insulating substrate 10, electrodes 20, 30 and a plurality of linear conductors 40. The linear conductor 40 is provided on the insulating substrate 10 and is covered with the insulating film 50. The linear conductor 40 is aluminum, and the insulating film 50 is a silicon oxide film. The circuit separation element 2 is further covered with a sealing material 80. The sealing material 80 is a general silicone gel as a sealing material for a power module.

FIG. 8B is a circuit diagram schematically showing the test circuit 300. In this circuit, a high-voltage separation test that simulates the short-circuit current with the discharge current of the capacitor can be performed. The power supply voltage Vs is 2 kV, the capacitor C is 3 μF, and the wiring inductance is 400 mH.

The circuit separation element 2 is connected to the capacitor C via a relay. After charging the capacitor C with the relay turned off, the relay is turned on and a discharge current is passed through the circuit separation element 2 to separate the linear conductor 40. During this time, the voltage waveform and the current waveform are measured with an oscilloscope connected to the measurement point between the relay and the circuit separation element 2.

9 (a) and 9 (b) are schematic views illustrating the voltage waveform and the current waveform measured by the test circuit 300. 9 (a) is a schematic diagram showing a voltage waveform, and FIG. 9 (b) is a schematic diagram showing a current waveform.

When the arc discharge after the linear conductor 40 is separated is suppressed, the stepped voltage waveform shown in FIG. 9A is observed at the measurement point. Further, the current waveform corresponding to this is in the form of a pulse shown in FIG. 9B. That is, the linear conductor 40 is blown by the current flowing at the moment when the relay is turned on, and the current path via the circuit separation element 2 is cut off. Then, the current value at the measurement point becomes zero.

On the other hand, when the arc discharge continues even after the linear conductor 40 is separated, a voltage waveform that decreases with the passage of time is observed, and the arc current continues to flow. This makes it possible to detect the presence or absence of arc discharge. Further, if the arc discharge is sustained, the silicone gel, which is a sealing member covering the linear conductor 40, is damaged. Therefore, the presence or absence of a continuous arc can be determined from the change in the appearance of the circuit separation element 2.

FIG. 10 is a schematic diagram showing the test results. FIG. 10 shows the relationship between the separation current flowing through each linear conductor 40 and the power supply voltage. Here, the result when the length L of the linear conductor 40 (see FIG. 8A) is set to 1 mm to 5 mm is shown. Here, the "separation current" is a current that blows the linear conductor 40, that is, a maximum current value that can be passed through each linear conductor 40.

The white circle A shown in FIG. 10 indicates the point where the arc discharge is suppressed, and the black circle B indicates the point where the arc discharge is sustained. Further, the region shown by the diagonal line represents a region in which the arc discharge can be suppressed.

As shown in FIG. 10, the range of the power supply voltage capable of suppressing the arc discharge changes depending on the length L of the linear conductor 40. Further, it can be seen that the arc discharge can be suppressed by setting the separation current to 40 A / line or less.

FIG. 11 is a schematic diagram showing another test result. FIG. 11 shows the relationship between the separation current flowing through each linear conductor 40 and the power supply voltage when the length L of the linear conductor 40 is 2 mm. Here, too, it can be seen that the arc discharge after the separation of the linear conductor 40 is suppressed in the range of the power supply voltage of 2 kV or less and the separation current of 40 A / line or less.

Table 1 shows the measurement results when the width WM of the linear conductor 40 (see FIG. 2A) is changed and the parallel number N thereof is changed. The separation current flowing through each linear conductor 40 varies in the range of 10A to 45A corresponding to the parallel number N of the linear conductors 40.

As shown in Table 1, it can be seen that the arc discharge can be suppressed by setting the separation current flowing through each linear conductor 40 to 40 A or less. By setting the separation current flowing through each linear conductor 40 to 40 A / piece in this way, it is possible to suppress the arc discharge after the linear conductor 40 is separated.

In other words, the minimum arc current value of the linear conductor 40 made of aluminum is 40 A / piece. Further, when the linear conductor 40 is formed by using a material other than aluminum, the minimum arc current is considered to be larger than 40 A / line. Therefore, regardless of the material used for the linear conductor 40, it is possible to determine the parallel number N of the linear conductor 40 with the minimum arc current of 40 A / line.

The minimum arc current based on the above measurement results is one digit or more larger than the material-specific minimum arc current disclosed in the above-mentioned research example. The reason for this is considered as follows.

The electrical contacts cut off the current, for example, by separating the exposed pair of metal members from the mechanically in contact state. When an attempt is made to cut off the current under a high voltage, a weak arc discharge is started with a minute gap formed between the metal members. Since there is no mechanism for suppressing this arc discharge, the arc discharge can be easily sustained even under a small separation current.

On the other hand, in the linear conductor 40 according to the embodiment, when a weak electric discharge occurs in the initial process of its separation, the insulating member existing around the linear conductor 40 maintains an insulating state and dissipates heat. Suppress arc discharge. That is, the insulating member covering the linear conductor 40 functions as an arc extinguishing material, and has an effect of suppressing discharge in the same manner as the arc extinguishing material used in a general high voltage fuse product.

Further, in the process leading to the electrical separation of the linear conductor 40, the temperature of the linear conductor 40 becomes higher than the melting point of the material. Therefore, the silicone gel used as the sealing material 80, the epoxy resin, the phenol resin, the polyimide resin, or the like is thermally decomposed to generate gas. Then, the gas that has flowed in between the minute gaps of the separated linear conductors 40 promotes heat dissipation, and as a result, the arc discharge after the separation of the linear conductors 40 is suppressed.

By providing the insulating film and the sealing material 80 that cover the linear conductor 40 in this way, the action of suppressing the arc discharge works, and the continuation of the arc discharge after separation can be avoided. Therefore, the measured minimum arc current is larger than the material-specific value.

As described above, the short-circuit current in the semiconductor device or the inverter is approximately 100A to 2000A. Therefore, when the minimum arc current is 40 A / line, the parallel number N of the linear conductors 40 is at least 3 to 50.

In addition, the continuation of the arc discharge may cause a serious secondary disaster such as a fire. Therefore, when the safety factor is 10 times, the threshold value of the separation current is 4 A / line, and the minimum value of the parallel number N of the linear conductors 40 is preferably at least 30 to 500.

Further, when a three-phase inverter circuit is configured by using the semiconductor device 100, the short-circuit current flowing through the transistor Tr1 is at least three times the maximum rated current Idmax of the semiconductor device 100, and the linear conductor 40 in the circuit separation element 2 The parallel number N is preferably 3Idmax / 40 or more. That is, the minimum value of the number N of parallel conductors 40 is at least the maximum rated current Idmax of the semiconductor device 100 divided by 40 A, which is the threshold value of the separation current in which the arc generated when the linear conductor 40 is separated is not sustained. It is desirable that it is larger than the value.

According to the above embodiment, the surplus inverter and semiconductor device used to give redundancy to the power control system are not required, and the weight and volume of the power control system can be reduced. Further, the circuit separation element 1 has fine linear conductors in parallel, and can reduce the current when each linear conductor is blown by Joule heat. This makes it possible to avoid the continuation of the arc discharge when the circuit is separated. This eliminates the need to use a large amount of arc extinguishing material as in a normal fuse, so that the mounting area of the circuit separation element 1 can be reduced. Further, when the circuit separation element 1 is mounted in the semiconductor device 100, for example, the sealing material of the semiconductor device 100 functions as an arc extinguishing material, and the continuation of the arc discharge at the time of circuit separation can be further suppressed.

Further, the semiconductor device 100 may have a function of notifying the outside of the transistor Tr when the circuit is separated by the circuit separation element 1. This makes it possible to estimate current load fluctuations for other healthy components, predict the uptime of a power control system, and create a maintenance plan. Therefore, the reliability and practicality of the entire power control system can be improved.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

1, 2 ... circuit separation element, 10 ... insulating substrate, 20, 30 ... electrode, 40 ... linear conductor, 50 ... insulating film, 50H ... opening, 60, 70 ... connecting member, 80 ... sealing material, 100, 200 ... Semiconductor device, 110, 120, 130 ... Wiring, 140 ... Connection conductor, 300 ... Test circuit, Tr, Tr1 to Trn ... Transistor

Claims (14)

With insulators
The first electrode provided on the insulator and
A second electrode provided on the insulator at a position separated from the first electrode, and
A plurality of linear conductors provided on the insulator and connected to the first electrode and the second electrode, respectively.
Equipped with
The number of the linear conductors is a circuit separation element larger than the value obtained by dividing the maximum current value flowing between the first electrode and the second electrode by the minimum arc current value of the linear conductors. The circuit separation element according to claim 1, wherein the minimum arc current value is 40 A. The circuit separation element according to claim 1, wherein the minimum arc current value is a value peculiar to the material of the linear conductor. Claims 1 to 3 in which, when a current having the maximum current value is passed between the first electrode and the second electrode, the first electrode and the second electrode are electrically separated from each other. The circuit separation element according to any one. The circuit separation element according to any one of claims 1 to 4, wherein the linear conductor contains an oxidizing metal whose oxide is a high resistor. The circuit separation element according to any one of claims 1 to 4, wherein the linear conductor includes either copper or aluminum. The circuit separation element according to any one of claims 1 to 6, wherein the first electrode and the second electrode include the same material as the linear conductor. The circuit separation element according to any one of claims 1 to 7, further comprising an insulating film covering the linear conductor. The circuit separation element according to any one of claims 1 to 8, wherein the insulator includes at least one of glass, ceramics, epoxy resin, phenol resin, polyimide and a fluororesin. A semiconductor element and a circuit separation element connected in series to the semiconductor element are provided.
The circuit separation element is
With insulators
The first electrode provided on the insulator and
A second electrode provided on the insulator at a position separated from the first electrode, and
A plurality of linear conductors provided on the insulator and connected to the first electrode and the second electrode, respectively.
Including
A semiconductor device having a maximum rated current smaller than the value obtained by multiplying the minimum arc current value of the linear conductor by the number of the linear conductors. The semiconductor device according to claim 10, wherein the minimum arc current value is 40 A. The semiconductor device according to claim 10, wherein the minimum arc current value is a value peculiar to the material of the linear conductor. A circuit in which a plurality of semiconductor elements including the semiconductor element are connected in parallel is provided.
The circuit separation element is connected in series to each of the plurality of semiconductor elements, and is connected to each of the plurality of semiconductor elements.
The semiconductor according to any one of claims 10 to 12, wherein when a current larger than the maximum rated current is passed through the circuit separation element, the semiconductor element connected in series to the circuit separation element is electrically separated from the circuit. Device. The first wiring on which the semiconductor element is mounted and
The second wiring arranged side by side with the first wiring and
Further prepare
The first electrode is connected to the first wiring via the first connecting member.
The second electrode is connected to the second wiring via the second connecting member.
The semiconductor device according to any one of claims 10 to 13, wherein the linear conductor is arranged so as to face a space between the first wiring and the second wiring.

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