JP2008198661A - Semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor device for electric power in which sensitivity of interruption function to interrupt excess current can be adjusted. <P>SOLUTION: The semiconductor device for electric power is provided with: a power semiconductor element 14; a first wiring conductor 21 connected to the power semiconductor element 14; a second wiring conductor 22 to supply electric power; an interruption conductor 23 that connects the first and second wiring conductors 21 and 22, and melts them at a specified temperature or more; a heater 26 to supply a heat to the interruption conductor 23; a heat sink 13 to cool the interruption conductor 23; a coolant supply means 27 to supply a coolant to the heat sink 13; and a control means 28 to control electric conduction to the heater 26 and also to control a quantity of coolant to be supplied by the coolant supply means 27. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power semiconductor device that supplies a current of several tens to several hundreds A, and more particularly to a power semiconductor device capable of adjusting sensitivity of a cutoff function that cuts off an overcurrent.

  The power semiconductor device energizes and cuts off a large current of several tens to several hundreds of A depending on whether the gate voltage of the power semiconductor element is on or off. That is, the power semiconductor device performs large energy control by a small energy control signal. The power semiconductor element generally has a structure that is finely formed on the surface of the Si substrate, and controls carriers by applying a voltage between the electrodes. Therefore, if a voltage or current outside the allowable range is applied and the energy density becomes extremely high, the surface of the semiconductor element is destroyed and current may flow unintentionally, so that current interruption is necessary.

  Common current interruption measures include no-fuse breakers and fuses. However, there is a problem that these have a large volume. In particular, power semiconductor devices for automobiles and the like are required to be lightweight from the viewpoint of fuel efficiency. On the other hand, a fuse mechanism that realizes a current interrupting function of a power semiconductor device with a small volume and cost has been proposed (for example, see Patent Documents 1 and 2). In this fuse mechanism, a metal wire or wiring is melted by an overcurrent.

JP 2005-175439 A JP 2006-120970 A

  When an automobile breaks down while traveling and then stops due to inertia, the rotation of the axle caused by the movement of the vehicle is converted into electric power by the generator. Normally, this power is regenerated to the battery. However, for example, in the case of a generator that does not have a clutch mechanism or the like and is directly connected to the axle, when the vehicle power electronics system goes down and the path to the battery is cut off, there is no destination for energy. For this reason, an unexpectedly large current is applied to the power semiconductor device without control, and there is a possibility that problems such as overheating may occur. In such a case, it is necessary to interrupt between the power semiconductor device and the generator.

  On the other hand, even if the current value is in the normal operation region, if the power electronics system goes down, there is no destination for energy, and overheating of the power semiconductor device may become a problem. As described above, the current value at which the current should be interrupted varies depending on the situation. Therefore, if the sensitivity adjustment of the interrupt function can be performed according to the situation, safety is improved. However, conventional power semiconductor devices cannot adjust the sensitivity of the cutoff function.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain a power semiconductor device capable of adjusting the sensitivity of a blocking function for blocking an overcurrent.

  A power semiconductor device according to the present invention includes a power semiconductor element, a first wiring conductor connected to the power semiconductor element, a second wiring conductor that supplies power, a first wiring conductor, and a second wiring conductor. And a heater that supplies heat to the interrupting conductor, a heat sink that cools the interrupting conductor, a refrigerant supply means that supplies refrigerant to the heat sink, and control of energization to the heater And a control means for controlling the amount of refrigerant supplied by the refrigerant supply means.

  According to the present invention, it is possible to adjust the sensitivity of the interruption function for interrupting overcurrent.

Embodiment 1 FIG.
FIG. 1 is a sectional view showing a power semiconductor device according to the first embodiment of the present invention. For example, a heat spreader 11 made of copper is mounted on a heat sink 13 via an insulating sheet 12 made of, for example, an epoxy resin. On the heat spreader 11, a power semiconductor element 14 such as an IGBT is soldered. The power semiconductor element 14 is connected to the lead frame 16 by an aluminum wire 15. These heat spreaders 11 and the like are sealed with a mold resin 17 made of, for example, an epoxy resin by using a transfer molding method.

  The first wiring conductor 21 is connected to the lead frame 16 by screws. Accordingly, the first wiring conductor 21 is connected to the power semiconductor element 14 via the lead frame 16 and the aluminum wire 15. The first wiring conductor 21 and the second wiring conductor 22 are connected by a blocking conductor 23. The second wiring conductor 22 supplies power from an external power source (not shown) to the power semiconductor element 14 via the blocking conductor 23, the first wiring conductor 21 and the lead frame 16.

  Here, the first wiring conductor 21 and the second wiring conductor 22 are made of, for example, Cu or a Cu alloy having a thickness of about 1 mm. The blocking conductor 23 is made of a low melting point material such as Sn, solder, Zn, Al or the like having a lower melting point than those of the first wiring conductor 21 and the second wiring conductor 22 and is melted at a predetermined temperature or higher. The blocking conductor 23 is preferably in an elongated shape in order to ensure blocking performance. Moreover, the interruption | blocking performance of the interruption | blocking conductor 23 improves by providing a part with a small cross-sectional area like a figure.

  When the blocking conductor 23 is melted, it is divided into a shape close to two spheres in contact with the first wiring conductor 21 and the second wiring conductor 22 so as to reduce the surface energy. Thereby, the 1st wiring conductor 21 and the 2nd wiring conductor 22 are interrupted | blocked. Therefore, it is preferable that the diameter of the sphere having a half of the volume of the blocking conductor 23 is smaller than the distance between the first wiring conductor 21 and the second wiring conductor 22 so that the blocking is facilitated.

  A substrate 24 is mounted on the heat sink 13. As the material of the substrate 24, for example, a material having heat resistance and insulating properties, such as a plate obtained by molding an epoxy resin, glass epoxy resin or PPS (polyphenylene sulfide) into a predetermined shape, mica paper, polyimide sheet, or the like is used. The terminal block 25 is made of an insulating resin having heat resistance, and is fixed to the heat sink 13 by bonding, caulking, screwing, or the like. The first wiring conductor 21 and the second wiring conductor 22 are fixed on the substrate 24 by adhesion, screw fixing, or the like, and are fastened with screws to nuts included in the terminal block 25. The blocking conductor 23 is disposed so as to be in direct contact with the substrate 24.

  A heater 26 for supplying heat to the blocking conductor 23 is provided in the vicinity of the blocking conductor 23. As the heater 26, a heater having a flat surface such as a ceramic heater is preferably used. Since a heater having a flat surface can reduce the thermal resistance to the interrupting conductor 23, the interrupting conductor 23 can be reliably melted without unnecessarily increasing the amount of heat generation. The heater 26 may be in direct contact with the blocking conductor 23 or may be in contact with an insulating film or the like. However, in order to maintain the insulation between the first wiring conductor 21 and the second wiring conductor 22 after the breaking conductor 23 is melted, the surface of the heater 26 that contacts the breaking conductor 23 is made of at least an insulating material. Or covered with an insulating coating.

  Further, the heater 26 is disposed on the opposite side of the heat sink 13 with respect to the blocking conductor 23. Thereby, the interruption | blocking conductor 23 can be arrange | positioned directly on the board | substrate 24, and heat dissipation can be ensured. However, the heater 26 can also be disposed closer to the heat sink 13 than the blocking conductor 23. In this case, heat is radiated from the blocking conductor 23 to the heat sink 13 through the heater 26. Therefore, in order to ensure heat dissipation, a material with good thermal conductivity having a thermal conductivity of, for example, 10 W / mK or more is used as the material of the heater 26.

  The coolant supply means 27 supplies coolant such as cooling water and cooling air to the heat sink 13. The control means 28 controls energization to the heater 26 and controls the amount of refrigerant supplied by the refrigerant supply means 27.

  Next, the operation of the power semiconductor device having the above configuration will be described. First, when increasing the sensitivity of the blocking function, the control unit 28 energizes the heater 26 and reduces the supply amount of the refrigerant by the refrigerant supply unit 27 or stops the supply of the refrigerant. Thereby, since the interruption | blocking conductor 23 is heated, it melts even below a rated current. On the other hand, when lowering the sensitivity of the blocking function, the control means 28 does not energize the heater 26 and increases the amount of refrigerant supplied by the refrigerant supply means 27. Thereby, since the interruption | blocking conductor 23 is cooled, even if a big electric current flows, it is hard to melt | fuse. As described above, the power semiconductor device according to the present embodiment can adjust the sensitivity of the interruption function for interrupting the overcurrent.

  Moreover, according to this Embodiment, it can interrupt | block also with the interruption | blocking conductor 23 with small resistance value. In other words, since the blocking conductor 23 having a small resistance value can be used, the volume of the blocking mechanism can be reduced. In general, the power semiconductor device is provided with a heat sink 13 for cooling the power semiconductor element 14. Therefore, if this heat sink 13 is used to cool the blocking conductor 23, an increase in cost for realizing the present embodiment can be suppressed.

Embodiment 2. FIG.
FIG. 2 is a sectional view showing a power semiconductor device according to the second embodiment of the present invention. A description of the same configuration as that of the first embodiment will be omitted, and a configuration different from that of the first embodiment will be described.

  The blocking conductor 23 and the heater 26 are collectively sealed with a mold resin 31 such as an epoxy resin or a polyphenylene sulfide (PPS) resin. The blocking conductor 23 is exposed from the surface of the mold resin 31 or is arranged close to the surface through a thin skin of about 0.1 mm. A heater 26 is formed in the mold resin 31 so that the wiring pattern is thinly corrugated.

  Thus, by making the shut-off mechanism a unit type, the mountability of the shut-off mechanism is increased, and the size and weight can be reduced.

  Further, since the blocking conductor 23 is exposed from the surface of the mold resin 31 or arranged close to the surface, the molten blocking conductor 23 flows out to the external space of the mold resin 31. For this reason, the space | gap for interrupting | blocking the 1st wiring conductor 21 and the 2nd wiring conductor 22 can be formed.

  The heater 26 is composed of a member having a thickness different from that of the frame, but may be composed of a part of the frame as long as an appropriate resistance value can be realized.

  In order not to unnecessarily increase the cross-sectional area of the blocking conductor 23, it is necessary to ensure heat dissipation from the blocking conductor 23 to the heat sink 13. Therefore, a mold having a thermal conductivity of about 3 W / mK by increasing the content of a filler such as silica, rather than a mold resin 31 having a thermal conductivity of about 0.7 W / mK, which is generally used in ICs and the like. It is preferable to use the resin 31.

  In addition, the temperature rise characteristic of the interruption | blocking conductor 23 can be stabilized by sticking the interruption | blocking conductor 23 to the heat sink 13 with heat conductive grease.

Embodiment 3 FIG.
FIG. 3 is a cross-sectional view showing a power semiconductor device according to the third embodiment of the present invention, and FIG. 4 is a plan view showing a blocking mechanism according to the third embodiment of the present invention. A description of the same configuration as that of the first embodiment will be omitted, and a configuration different from that of the first embodiment will be described.

  The heater 26 is disposed so as to overlap in the vertical direction with a distance that achieves both insulation and thermal conductivity with respect to the blocking conductor 23, and is connected to the control means 28 via the heater electrode 33. The blocking conductor 23 and the heater 26 are collectively sealed with a mold resin 31 such as an epoxy resin or a polyphenylene sulfide (PPS) resin.

  The thickness of the mold resin 31 between the blocking conductor 23 and the heat sink 13 is 0.3 mm or more and 1 mm or less. By making the thickness of this part 0.3 mm or more, it is possible to prevent the occurrence of defects due to pinholes or voids, to ensure insulation, and to provide a mold resin 31 having a thickness that is not inconvenient for production on the bottom side. Can be secured. On the other hand, by setting the thickness of this portion to 1 mm or less, the heat dissipation from the blocking conductor 23 to the heat sink 13 is improved, and the selectable range of the resistance value of the blocking conductor 23 is increased.

  The mold resin 31 is provided with a recess 32 on the blocking conductor 23 leaving a thin skin of about 0.1 mm. As a result, the melted blocking conductor 23 flows out to the external space of the mold resin 31. For this reason, the space | gap for interrupting | blocking the 1st wiring conductor 21 and the 2nd wiring conductor 22 can be formed. In addition, since there is no member which needs to ensure insulation above the recessed part 32 and there may be a pinhole etc., the mold resin 31 on the recessed part 32 may be thinner.

Embodiment 4 FIG.
FIG. 5 is a sectional view showing a power semiconductor device according to the fourth embodiment of the present invention. As illustrated, the power semiconductor element 14, the heater 26, and the blocking conductor 23 are collectively sealed with a mold resin 34. That is, a blocking mechanism and a heater are incorporated in a part of the resin-encapsulated power module. Other configurations are the same as those in the second or third embodiment. Thereby, in addition to the same effects as those of the second or third embodiment, the assembling property of the power semiconductor device can be improved, and the size, weight, and cost can be reduced. In particular, as shown in the figure, the mold resin 34 wraps under the heater 26, so that the substrate is not required and the cost is reduced.

1 is a cross-sectional view showing a power semiconductor device according to a first embodiment of the present invention. It is sectional drawing which shows the power semiconductor device which concerns on Embodiment 2 of this invention. It is sectional drawing which shows the semiconductor device for electric power which concerns on Embodiment 3 of this invention. It is a top view which shows the interruption | blocking mechanism which concerns on Embodiment 3 of this invention. It is sectional drawing which shows the power semiconductor device which concerns on Embodiment 4 of this invention.

Explanation of symbols

13 Heat sink 14 Power semiconductor element 21 First wiring conductor 22 Second wiring conductor 23 Breaking conductor 26 Heater 27 Refrigerant supply means 28 Control means 31, 34 Mold resin 32 Recess

Claims (4)

A power semiconductor element;
A first wiring conductor connected to the power semiconductor element;
A second wiring conductor for supplying power;
A blocking conductor that connects the first wiring conductor and the second wiring conductor and melts at a predetermined temperature or more;
A heater for supplying heat to the blocking conductor;
A heat sink for cooling the blocking conductor;
Refrigerant supply means for supplying refrigerant to the heat sink;
A power semiconductor device comprising: control means for controlling energization to the heater and controlling the amount of refrigerant supplied by the refrigerant supply means.   2. The electric power device according to claim 1, wherein the heater and the interrupting conductor are collectively sealed with a resin, and the interrupting conductor is exposed from the surface of the resin or arranged close to the surface. Semiconductor device.   The heater and the blocking conductor are collectively sealed with a resin, and the thickness of the resin between the blocking conductor and the heat sink is not less than 0.3 mm and not more than 1 mm. The power semiconductor device according to claim 1, wherein a recess is provided.   4. The power semiconductor device according to claim 2, wherein the power semiconductor element, the heater, and the blocking conductor are collectively sealed with the resin. 5.

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