JP2017208738A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device which inhibits electrical rupture on a side of a power module mounted with a voltage detection element even when disconnection occurs on wiring for connecting a control circuit and the voltage detection element having high breakdown voltage.SOLUTION: A semiconductor device comprises: a power module including a switching element having a first output terminal being one of two output terminals and applied with a power supply voltage, and having the other second output terminal; and a control circuit board which has a voltage detection part for detecting an output voltage being a potential difference between the first output terminal and the second output terminal, and which is connected to the power module. The power module includes: a voltage detection element provided between the first output terminal and the control circuit board in an inserted manner for detecting the output voltage; and a potential decision element provided between the second output terminal and a midpoint between the voltage detection element and the control circuit board in the inserted manner.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a semiconductor device having a voltage detection element for detecting an output voltage corresponding to an ON voltage of a switching element.

  Patent Document 1 discloses a semiconductor device for driving a switching element (IGBT) and monitoring a voltage at an output terminal of the switching element via a high voltage diode. In this semiconductor device, a high voltage corresponding to the power supply voltage of the IGBT is applied to the cathode of a high voltage diode as a voltage detection element, and a low voltage corresponding to the power supply on the control circuit side is applied to the anode.

  For this reason, in the embodiment in which the high voltage diode is mounted on the substrate on the control circuit side, it is necessary to secure an insulation distance that can withstand the high voltage in the vicinity of the anode terminal of the high voltage diode. That is, the size of the substrate becomes large.

JP2013-223212A

  On the other hand, it is possible to consider a mode in which a high voltage diode is incorporated in the switching element or in an element module on which the switching element is mounted. In such a form, it is not necessary to design the insulation of the substrate, so that the substrate can be downsized.

  However, when a disconnection occurs between the element module and the substrate on the control circuit side, a high voltage is applied to the terminals of the element module, and there is a possibility that dielectric breakdown may occur on the element module side.

  The present invention has been made in view of the above problems, and in a semiconductor device having a voltage detection element for detecting an output voltage of a switching element, a wiring connecting a control circuit and a high withstand voltage detection element. An object of the present invention is to provide a semiconductor device that suppresses electrical breakdown even when disconnection occurs.

  The invention disclosed herein employs the following technical means to achieve the above object. Note that the reference numerals in parentheses described in the claims and in this section indicate a corresponding relationship with specific means described in the embodiments described later as one aspect, and limit the technical scope of the invention. Not what you want.

  In order to achieve the above object, the present invention includes a first output terminal (T1) that is one of two output terminals and to which a power supply voltage is applied, and the other second output terminal (T2). A control circuit board (200) including a power module (120) including a switching element (10) and including a voltage detection unit (211) that detects an output voltage that is a potential difference between the first output terminal and the second output terminal. 200) is a semiconductor device connected to the power module, the power module being inserted between the first output terminal and the control circuit board, and a voltage detection element (20, 60) for detecting the output voltage And a potential determination element (30, 40, 50) inserted between the midpoint of the voltage detection element and the control circuit board and the second output terminal.

  According to this, even when the high voltage wiring between the power module and the control circuit board and between the voltage detection element and the voltage detection unit is disconnected, the terminal on the control circuit board side in the voltage detection element is electrically connected. Without being floated on, it is connected to the second output terminal of the switching element via the potential determination element. For this reason, the terminal on the power module side extending from the voltage detection element can be fixed at a potential defined by the potential determination element, and phenomena such as creeping discharge due to a high voltage can be suppressed.

It is a circuit diagram which shows the structure of the semiconductor device and control circuit board in 1st Embodiment. It is a circuit diagram which shows the structure of the semiconductor device in 2nd Embodiment, and a control circuit board. It is a circuit diagram which shows the structure of the semiconductor device in 3rd Embodiment, and a control circuit board. It is a circuit diagram which shows the structure of the semiconductor device and control circuit board in other embodiment. It is a circuit diagram which shows the structure of the semiconductor device in other embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same reference numerals are given to the same or equivalent parts. In the case where only a part of the configuration is described in each embodiment, the other parts of the configuration are the same as those described previously. In addition to the combination of parts specifically described in each embodiment, the embodiments may be partially combined as long as the combination is not particularly troublesome.

(First embodiment)
First, a schematic configuration of the semiconductor device according to the present embodiment will be described with reference to FIG.

  This semiconductor device is a power switching device that is mounted on a vehicle, for example, and controls driving of a load based on an input control signal. As shown in FIG. 1, the semiconductor device 100 includes a power module 120 on which a power element 110 including a switching element 10 is mounted. A control circuit board 200 on which a control circuit 210 for controlling on / off of the switching element 10 is mounted is connected to the power module 120 via various wirings 300. Specifically, a gate wiring 310 for transmitting a control signal for controlling on / off of the switching element 10, a voltage detection wiring 320 for transmitting an output voltage of the switching element 10, a control circuit 210, the switching element 10, The power module 120 and the control circuit board 200 are connected to each other through a reference potential wiring 330 for sharing the reference potential. A terminal on the power module 120 side to which the wiring 300 is connected may be referred to as a module side terminal, and a terminal on the control circuit board 200 side may be referred to as a board side terminal.

  The power element 110 in this embodiment includes a switching element 10, a high voltage diode 20, and a resistor 30. The power element 110 forms an element as one chip, and one control terminal T0 and two output terminals T1 and T2 are formed so as to be connectable to the outside.

  As the switching element 10, for example, an insulated gate bipolar transistor (IGBT) can be adopted. As shown in FIG. 1, the gate terminal in the IGBT corresponds to the control terminal T0, the collector terminal corresponds to the output terminal T1, and the emitter terminal corresponds to the output terminal T2. The first output terminal described in the claims corresponds to the output terminal T1 as a collector terminal, and the second output terminal corresponds to the output terminal T2 as an emitter terminal. Although not shown, a power supply voltage VDD that generates a voltage to be supplied to the load is applied to the collector terminal T1 of the switching element 10. On the other hand, a ground potential common to the control circuit board 200 is connected to the emitter terminal T2. Needless to say, the switching element 10 is not limited to the IGBT, and may be a MOSFET, for example. When the switching element 10 is a MOSFET, the output terminal T1 corresponds to the drain terminal, and the output terminal T2 corresponds to the source terminal.

  The high voltage diode 20 is a generally known diode element. Hereinafter, the forward voltage in the high voltage diode 20 is denoted as VF. The cathode terminal of the high voltage diode 20 is connected to the collector terminal T1 of the switching element 10. The anode terminal of the high voltage diode 20 is connected to a voltage detection unit 211 (to be described later) in the control circuit board 200. The high breakdown voltage diode 20 is a voltage detection element for detecting the collector-emitter voltage of the IGBT, that is, the output voltage of the switching element 10. Specifically, when the switching element 10 is in the on state, the detection voltage output to the anode side of the high voltage diode 20 is the sum of the on voltage Von of the switching element 10 and the forward voltage VF of the high voltage diode 20. . For example, when an overcurrent flows as the collector current of the switching element 10, the on-voltage increases and the detection voltage also increases.

  Resistor 30 is a commonly known resistor. Hereinafter, the resistance value of the resistor 30 is expressed as R. One end of the resistor 30 is connected to the anode terminal of the high voltage diode 20, and the other end is connected to the emitter terminal T <b> 2 of the switching element 10. That is, the anode terminal of the high voltage diode 20 is connected to the ground via the resistor 30. The midpoint between the high voltage diode 20 and the resistor 30 is connected to the voltage detector 211. The resistor 30 in this embodiment corresponds to the potential determination element described in the claims. A suitable condition for the resistance value R of the resistor 30 will be described later.

  The power element 110 in this embodiment is mounted in the power module 120. As shown in FIG. 1, the power module 120 has five module-side terminals as connection terminals with the outside. That is, a gate terminal T0 as a control terminal, a collector terminal T1 as a first output terminal, an emitter terminal T2 as a second output terminal, and an anode terminal of the high breakdown voltage diode 20 are connected to detect the output voltage. The detection terminal T3 has a reference terminal T4 for making the reference potentials of the power module 120 and the control circuit board 200 the same. The gate terminal T0 is connected to the control circuit board 200 by a gate wiring 310. The detection terminal T3 is connected to the control circuit board 200 by a voltage detection wiring 320. The reference terminal T4 is connected to the control circuit board 200 by a reference potential wiring 330.

  The control circuit board 200 includes a control circuit 210, a gate resistor 220, a current limiting resistor 230, and a blanking capacitor 240.

  The control circuit 210 outputs a gate voltage as a control signal to the gate terminal T0 in the switching element 10. The control circuit 210 includes a voltage detection unit 211, and performs gate voltage control or fail-safe control based on the detected output voltage of the switching element 10. The control circuit 210 in the present embodiment is configured as an application specific integrated circuit, and is mounted on the control circuit board 200 as one chip. VCC is supplied to the control circuit 210 as a power supply voltage.

  The voltage detection unit 211 is a functional unit built in the control circuit 210 and detects a detection voltage output to the voltage detection terminal T3, that is, Von + VF. For example, when an overcurrent flows through the switching element 10, Von increases, so that the detection voltage Von + VF also increases. The control circuit 210 performs control such as performing a fail-safe operation on condition that the detected voltage is equal to or higher than a predetermined threshold.

  The voltage detector 211 has a function of outputting a constant current to the voltage detection terminal T3. When the switching element 10 is turned on, a current I is generated and supplied to the voltage detection terminal T3. The current value of the current I is defined based on the constant voltage Vc generated in the voltage detector 211. On the other hand, when the switching element 10 is turned off or in a short circuit state, the high voltage diode 20 is turned off, so that the constant voltage Vc is output to the voltage detection terminal T3. The constant voltage Vc may be the power supply voltage VCC itself supplied to the control circuit 210, or may be a voltage generated inside the control circuit 210.

  The gate resistor 220 is inserted between a driver (not shown) included in the control circuit 210 and the gate terminal T0 of the switching element 10. The gate resistor 220 is inserted for the purpose of optimizing the gate charge / discharge time during the switching operation.

  The current limiting resistor 230 is inserted between the voltage detection terminal T3 and the voltage detection unit 211. The current limiting resistor 230 is inserted for the purpose of suppressing the transient current during the switching operation.

  The blanking capacitor 240 is a capacitor inserted between a wiring connecting the current limiting resistor 230 and the voltage detection unit 211 and a reference potential (ground). The blanking capacitor 240 is inserted so that the fail-safe operation is not performed until the IGBT collector-emitter voltage becomes equal to or lower than the IGBT short-circuit determination voltage when the switching element 10 is turned on. ing. This time (blanking time) can be set longer as the capacity value of the blanking capacity 240 is larger.

  Then, the effect by employ | adopting the semiconductor device 100 in this embodiment is demonstrated.

  Assume that the voltage detection wiring 320 is disconnected. The anode terminal of the high voltage diode 20 in this embodiment is connected to the ground via the resistor 30. Therefore, with respect to the disconnection of the voltage detection wiring 320, the voltage detection terminal T3 from which the voltage of the anode terminal is output is regulated to a value corresponding to the resistance value R of the resistor 30 without being electrically floating. Can do. That is, the resistor 30 is a potential determination element that determines the voltage detection terminal T3 at a predetermined potential. Therefore, it is possible to prevent a high voltage resulting from the power supply voltage from being output to the voltage detection terminal T3, and it is possible to suppress a breakdown phenomenon due to the occurrence of creeping discharge around the voltage detection terminal T3.

  Subsequently, a suitable resistance value R of the resistor 30 in the semiconductor device 100 will be described.

  It is desirable that the short circuit of the switching element 10 can be detected also by the insertion of the resistor 30. Hereinafter, the resistance value R that enables short-circuit detection of the switching element 10 while suppressing the output of a high voltage to the voltage detection terminal T3 will be described. In the description, a collector-emitter voltage when a rated current (maximum current as a collector current) flows through the switching element 10 is denoted as Vmax. Vmax is a value that is uniquely determined when the rated current and the switching element 10 are determined, and is a voltage value that indicates the maximum value of the ON voltage.

  When the IGBT which is the switching element 10 is in the ON state, the collector-emitter voltage takes a value between 0 and Vmax. Therefore, the potential difference Eon between the reference potential terminal T4 serving as the reference potential and the voltage detection terminal T3, that is, the voltage of the voltage detection terminal T3 satisfies the relationship of VF ≦ Eon ≦ VF + Vmax.

  On the other hand, when the IGBT is off or the IGBT is short-circuited, the high voltage diode 20 is not energized. At this time, in order to determine that the IGBT is in a short circuit state, the voltage Eoff of the voltage detection terminal T3 must be able to take a value that is at least larger than the maximum value of Eon. In other words, in order to detect a short circuit, the threshold value must be at least a voltage value larger than the maximum value of Eon. That is, it is necessary to satisfy the relationship of Eoff> VF + Vmax.

Since the high voltage diode 20 is not energized in the short-circuit state, Eoff is Eoff = I × R using the constant current I and the resistance value R. Therefore, I × R> VF + Vmax, and the resistance value R is
R> (VF + Vmax) / I
It is desirable to satisfy the relationship.

(Second Embodiment)
In the first embodiment, the example in which the resistor 30 is employed as the potential determination element has been described. On the other hand, as shown in FIG. 2, the semiconductor device 101 according to the present embodiment employs a capacitor 40 instead of the resistor 30 as a potential determination element. The anode terminal of the high voltage diode 20 in this embodiment is connected to the ground via the capacitor 40. For this reason, with respect to the disconnection of the voltage detection wiring 320, the voltage detection terminal T3 from which the voltage of the anode terminal is output can be regulated to a value corresponding to the capacitance value C of the capacitor 40 without being electrically floating. it can.

  A suitable capacitance value C of the capacitor 40 in the semiconductor device 101 will be described.

Assume that the voltage detection wiring 320 is disconnected. A potential difference between the reference potential terminal T4 and the voltage detection terminal T3 serving as a reference potential, that is, a voltage at the voltage detection terminal T3 is E, and a cathode-anode capacitance of the high voltage diode 20 is Cak. With respect to the collector-emitter voltage V of the IGBT, the voltage E of the voltage detection terminal T3 is E = V × Cak / (C + Cak). The voltage E may be lower than the required terminal breakdown voltage Va in the power module 120 (E <Va), and the collector-emitter voltage V is assumed to be the maximum rated voltage Vr applied when the switching element 10 is turned off. Since the capacitance value C is good,
Cak / (C + Cak) <Va / Vr
It is desirable to satisfy the relationship.

(Third embodiment)
In addition to the resistor 30 and the capacitor 40, a clamp element can be employed as the potential determination element. As shown in FIG. 3, the semiconductor device 102 according to the present embodiment employs a Zener diode 50 that is one of clamp elements as a potential determination element. The Zener diode 50 has a cathode terminal connected to the anode terminal of the high voltage diode 20. In the present embodiment, the anode terminal of the high voltage diode 20 is connected to the ground via a Zener diode 50 that is a clamp element. For this reason, the voltage detection terminal T3 from which the voltage of the anode terminal of the high-breakdown-voltage diode 20 is output with respect to the disconnection of the voltage detection wiring 320 does not float electrically, and corresponds to the breakdown voltage Vz of the Zener diode 50. Value can be specified.

  A suitable breakdown voltage Vz of the Zener diode 50 in the semiconductor device 102 will be described.

In order to detect the collector-emitter voltage (output voltage) of the switching element 10, the breakdown voltage Vz must be larger than the power supply voltage VCC on the control circuit board 200 side. Further, since the breakdown voltage Vz is output to the voltage detection terminal T3 when the voltage detection wiring 320 is disconnected, the breakdown voltage Vz is required to be lower than the required inter-terminal breakdown voltage Va in the power module 120. That is, the breakdown voltage Vz is
VCC <Vz <Va
It is desirable to satisfy the relationship.

(Other embodiments)
The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  In each of the embodiments described above, an example in which the high voltage diode 20 as the voltage detection element and the potential determination elements 30, 40, 50 are configured inside the power element 110 has been described, but these elements are arranged outside the power element 110. The power module 120 may be configured together with the power element. Furthermore, the high voltage diode 20 and the potential determination elements 30, 40, 50 may be disposed outside the power module.

  Further, in the manufacturing stage of the semiconductor devices 100, 101, 102, if the potential determination elements 30, 40, 50 are connected in advance to the anode terminal of the high voltage diode 20, noise is measured when measuring the leakage current of the switching element 10. There is a risk of becoming. In such a case, the potential determination elements 30, 40 and 50 may not be connected at the time of leak current inspection, and may be connected by means such as wire bonding after the inspection.

  In each of the above-described embodiments, the example in which the potential determining elements 30, 40, and 50 are arranged only on the power module 120 side has been described. However, as shown in FIG. A potential determination element may be arranged. In the example shown in FIG. 4, the second potential determination element is a Zener diode 250, the cathode terminal is connected to the wiring connected to the voltage detection wiring 320, and the anode terminal is connected to the wiring connected to the reference potential wiring 330. For example, the breakdown voltage of the Zener diode 50 that is a potential determination element disposed on the power module 120 side is 50 V, and the breakdown voltage of the Zener diode 250 that is the second potential determination element disposed on the control circuit board 200 is 35 V. In this case, the creepage on the module side may be 50V withstand voltage design, and the creepage on the substrate side may be with 35V withstand voltage design.

  In each of the embodiments described above, an example in which the gate resistor 220, the current limiting resistor 230, and the blanking capacitor 240 are included in the control circuit board 200 has been described. However, the gate resistor 220, the current limiting resistor 230, The ranking capacitor 240 may be mounted so as to be included on the power module 120 side, or may be mounted outside the control circuit board 200 and the power module 120.

  In each of the above-described embodiments, the example in which the high voltage diode 20 is employed as the voltage detection element for detecting the output voltage of the switching element 10 has been described. However, the voltage detection element is not limited to the high voltage diode 20. For example, as illustrated in FIG. 5, the semiconductor device 103 includes a high voltage capacitor 60 and a resistor 61 instead of the high voltage diode 20. The high-voltage capacitor 60 is connected to a collector terminal T1 that is a first output terminal and a cathode terminal of a Zener diode 50 that is a potential determination element. An intermediate point between the high voltage capacitor 60 and the Zener diode 50 is connected to the voltage detection terminal T3 and to the ground via the resistor 61. The high-voltage capacitor 60 and the resistor 61 constitute a differentiation circuit, and output dV / dt to the voltage detection terminal T3 with respect to the output voltage V of the switching element 10.

  In the third embodiment, the Zener diode 50 is shown as an example of the clamp element. However, the present invention is not limited to this. For example, the Zener diode may be connected in series, and the breakdown voltage is set to a predetermined value. Any possible element and structure can be used.

DESCRIPTION OF SYMBOLS 10 ... Switching element, 20 ... High voltage | pressure-resistant diode (voltage detection element), 30 ... Resistor (potential determination element), 100, 101, 102, 103 ... Semiconductor device, 110 ... Power element, 120 ... Power module, 200 ... Control Circuit board 210 ... Control circuit 211 ... Voltage detector

Claims (8)

A power module (120) including a switching element (10) having a first output terminal (T1) to which a power supply voltage is applied and one of the two output terminals, and the other second output terminal (T2). )
A semiconductor device in which a control circuit board (210) including a voltage detector (211) that detects an output voltage that is a potential difference between the first output terminal and the second output terminal is connected to the power module. ,
The power module is
A voltage detecting element (20, 60) inserted between the first output terminal and the control circuit board for detecting the output voltage;
A semiconductor device comprising: a potential determination element (30, 40, 50) inserted between a midpoint of the voltage detection element and the control circuit board and the second output terminal.   2. The semiconductor device according to claim 1, wherein the voltage detection element is a diode, a cathode terminal of the diode is connected to the first output terminal, and an anode terminal is connected to the voltage detection unit.   The semiconductor device according to claim 1, wherein the potential determination element is a resistor (30). The voltage detection element is a diode having a cathode terminal connected to the first output terminal, an anode terminal connected to the voltage detection unit, and a forward voltage of VF.
The resistance value R of the resistor is obtained by using a maximum value Vmax of an on-voltage in the switching element and a current value I supplied from the control circuit board to the anode terminal,
R> (VF + Vmax) / I
The semiconductor device according to claim 3, satisfying the relationship:   The semiconductor device according to claim 1, wherein the potential determination element is a capacitor (40). The voltage detection element is a diode in which a cathode terminal is connected to the first output terminal, an anode terminal is connected to the voltage detection unit, and a capacitance between the cathode and the anode is Cak,
Between the capacitance C of the capacitor, the rated voltage Vr in the switching element, and the terminal breakdown voltage in the power module Va.
Cak / (C + Cak) <Va / Vr
The semiconductor device according to claim 5, wherein:   The semiconductor device according to claim 1, wherein the potential determination element is a clamp element (50) having a breakdown voltage Vz. Between the breakdown voltage Vz, the constant voltage Vc generated in the control circuit board and supplied to the midpoint of the voltage detection element and the control circuit board, and the terminal breakdown voltage in the power module between Va,
Vc <Vz <Va
The semiconductor device according to claim 7, wherein:

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