Semiconductor devices and equipment

Abstract

In conventional devices, it is not easy to change the clamping voltage. The present invention provides a semiconductor device, comprising: a semiconductor switch; an external package body in which the semiconductor switch is built; a drain terminal electrically connected to the drain of the semiconductor switch and exposed from the external package body; a plurality of voltage clamping elements connected in cascade between the drain terminal and the gate of the semiconductor switch; and a voltage clamping terminal electrically connected between two voltage clamping elements among the plurality of voltage clamping elements and exposed from the external package body.

Description

Technical Field

[0001] The present invention relates to semiconductor devices and apparatus. Background Art

[0002] Conventionally, a clamp circuit is provided in a semiconductor switch connected to an inductive load to prevent damage to the semiconductor switch by clamping a voltage applied to the semiconductor switch to a clamp voltage when power supply to the inductive load is cut off (see, for example, Patent Documents 1 to 4).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2012-4979

[0006] Patent Document 2: Japanese Patent Application Publication No. 2016-167693

[0007] Patent Document 3: Japanese Patent Application Publication No. 2006-216651

[0008] Patent Document 4: International Publication No. 2015 / 198435 Summary of the invention

[0009] Technical issues

[0010] However, in conventional devices, the clamp voltage cannot be easily changed.

[0011] Technical Solution

[0012] In order to solve the above-mentioned problems, a semiconductor device is provided in a first embodiment of the present invention. The semiconductor device may include a semiconductor switch. The semiconductor device may include an external package body in which the semiconductor switch is built. The semiconductor device may include a drain terminal electrically connected to the drain of the semiconductor switch and exposed from the external package body. The semiconductor device may include a plurality of voltage clamping elements connected in cascade between the drain terminal and the gate of the semiconductor switch. The semiconductor device may include a voltage clamping terminal electrically connected between any two or more adjacent groups of voltage clamping elements among the plurality of voltage clamping elements and exposed from the external package body.

[0013] A plurality of voltage clamping elements may be disposed within the external package.

[0014] When the voltage clamp terminal is connected to the drain terminal, it is possible to bypass one or more of the plurality of voltage clamp elements on a path from the drain terminal to the gate.

[0015] At least one voltage clamping element may be provided in cascade connection between the voltage clamping terminal and a node between two voltage clamping elements.

[0016] The number of voltage clamping elements between the drain terminal and the node among the plurality of voltage clamping elements may be different from the number of the at least one voltage clamping element.

[0017] The semiconductor device may include a plurality of voltage clamp terminals respectively connected to a plurality of nodes between two voltage clamp elements among the plurality of voltage clamp elements.

[0018] The semiconductor device may further include a gate control circuit for controlling a gate of the semiconductor switch. The semiconductor device may further include a source terminal electrically connected to a source of the semiconductor switch and exposed from an external package.

[0019] In a second aspect of the present invention, a device is provided. The device may include a positive power supply. The device may include the semiconductor device of the first aspect. The device may include an inductive load connected in series with the semiconductor device between the positive power supply and ground.

[0020] In addition, the above-mentioned invention content does not list all necessary features of the present invention. In addition, sub-combinations of these feature groups may also constitute inventions. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A device according to this embodiment is shown.

[0022] Figure 2 Indicates the current path in a state where the voltage clamp terminal and the drain terminal are connected.

[0023] Figure 3 The appearance of the semiconductor device according to this embodiment is shown.

[0024] Explanation of symbols

[0025] 1: device, 2: inductive load, 3: positive power supply, 4: semiconductor device, 40: external package, 41: terminal, 42: semiconductor switch, 43: gate control circuit, 44: clamp circuit, 401: lead frame, 410: control terminal, 411: ground terminal, 412: drain terminal, 413: source terminal, 414: voltage clamp terminal, 440: voltage clamp element, 441: diode, 442: resistor, 443: resistor, 401: lead frame, 402: mold resin portion, 4010: lead frame body, 4011: lead frame segment DETAILED DESCRIPTION

[0026] Hereinafter, the present invention will be described by way of the embodiments of the invention, but the following embodiments do not limit the invention involved in the claims. In addition, not all combinations of features described in the embodiments are essential to the solution of the invention.

[0027] Figure 1 The device 1 of this embodiment is shown. The device 1 includes one or more inductive loads 2, a positive power supply 3, and a semiconductor device 4.

[0028] One or more inductive loads 2 are connected in series with the semiconductor device 4 between the positive power supply 3 and the ground. In the present embodiment, as an example, the inductive load 2 is connected between the semiconductor device 4 and the ground, but it can also be connected between the semiconductor device 4 and the positive power supply 3. In addition, in the present embodiment, as an example, the device 1 includes one inductive load 2. The inductive load 2 can be a valve body such as a solenoid valve or a hydraulic valve, or a motor or a transformer.

[0029] The positive power supply 3 supplies power to one or more inductive loads 2. For example, when the device 1 has one inductive load 2, the positive power supply 3 can supply 13V, 1A power to the inductive load 2.

[0030] The semiconductor device 4 switches the power supply to the inductive load 2. The semiconductor device 4 includes an external package 40, a plurality of terminals 41, a semiconductor switch 42, a gate control circuit 43, and a clamp circuit 44.

[0031] The external package 40 contains a semiconductor switch 42. The external package 40 can hermetically hold the semiconductor switch 42 inside. The external package 40 can be a transfer molded package or a box-shaped package in which a sealing resin is injected into a box.

[0032] The plurality of terminals 41 are respectively exposed from the external package body 40. For example, the plurality of terminals 41 include: a terminal (also referred to as a control terminal) 410 for receiving an input signal for the gate control circuit 43 from the outside, a terminal (also referred to as a ground terminal) 411 connected to the ground, a terminal (also referred to as a drain terminal) 412 connected to the positive electrode of the positive power supply 3, a terminal (also referred to as a source terminal) 413 connected to the inductive load 2, and a terminal (also referred to as a voltage clamp terminal) 414 that can be connected to the drain terminal 412.

[0033] The semiconductor switch 42 controls the power supply to the inductive load 2. In the present embodiment, as an example, the drain of the semiconductor switch 42 is connected to the drain terminal 412, the source is connected to the source terminal 413, and the gate is connected to the gate control circuit 43. The semiconductor switch can be a field effect transistor such as a MOSFET (metal-oxide-semiconductor field-effect transistor). Alternatively, the semiconductor switch 42 can also be an IGBT (Insulated Gate Bipolar Transistor).

[0034] The gate control circuit 43 controls the gate of the semiconductor switch 42. The gate control circuit 43 may be provided between the gate of the semiconductor switch 42 and the control terminal 410, and supplies a control signal based on a signal input via the control terminal 410 to the gate of the semiconductor switch 42 via a resistor 442 described later. The gate control circuit 43 may be connected to the ground via a ground terminal 411. The gate control circuit 43 may be disposed in the external package 40.

[0035] The clamp circuit 44 clamps the voltage applied to the semiconductor switch 42 when the power supply to the inductive load 2 is cut off, thereby preventing damage to the semiconductor switch 42. The clamp circuit 44 includes a plurality of voltage clamp elements 440, a diode 441, and one or more (two as an example in this embodiment) resistors 442 and 443. In this embodiment, as an example, each component of the clamp circuit 44 is arranged in the external package 40.

[0036] The plurality of voltage clamp elements 440 are connected in cascade between the drain terminal 412 and the gate of the semiconductor switch 42. In the present embodiment, three voltage clamp elements 440 (also referred to as voltage clamp elements 440(1) to 440(3)) are provided in the clamp circuit 44 as an example.

[0037] The voltage clamping element 440 can prevent current from flowing when a voltage lower than a reference voltage is applied, and can allow current to flow when a voltage higher than the reference voltage is applied. In the present embodiment, as an example, the voltage clamping elements 440 (1) to 440 (3) can allow current to flow when voltages higher than the reference voltage (V1 to V3) are applied respectively. Thus, the plurality of voltage clamping elements 440 can prevent current from flowing when a voltage lower than a clamping voltage (also called a breakdown voltage) Vc is applied as a whole, and can allow current to flow when a voltage higher than the clamping voltage Vc is applied as a whole, thereby clamping the voltage at both ends to the clamping voltage Vc. The clamping voltage can be the sum of the reference voltages V1 to V3 of the respective voltage clamping elements 440, and can be 50V as an example. The reference voltages V1 to V3 can be equal to each other or different from each other. In the present embodiment, as an example, each voltage clamping element 440 can be a Zener diode, whose cathode faces the drain terminal 412 side. In addition, the voltage clamp element 440 may be another diode such as a trigger diode, or may be an element other than a diode.

[0038] The voltage clamp terminal 414 is electrically connected between two adjacent voltage clamp elements 440 among the plurality of voltage clamp elements 440. Thus, when the voltage clamp terminal 414 is connected to the drain terminal 412, one or more of the plurality of voltage clamp elements 440 are bypassed on the path from the drain terminal 412 to the gate of the semiconductor switch 42. In the present embodiment, as an example, the voltage clamp terminal 414 is connected between two voltage clamp elements 440 (1) and 440 (2) closest to the drain terminal 412, and when the voltage clamp terminal 414 is connected to the drain terminal 412, the voltage clamp element 440 (1) is bypassed.

[0039] The diode 441 is a diode for temperature compensation of the voltage clamp element 440. The diode 441 may be connected in series with the plurality of voltage clamp elements 440 between the drain terminal 412 and the gate of the semiconductor switch 42. The cathode of the diode 441 may face the gate side.

[0040] The resistors 442 and 443 are connected in series between the gate of the semiconductor switch 42 and the source terminal 413. The resistors 442 and 443 can generate a gate voltage according to the current flowing between the source terminal 413 and the gate of the semiconductor switch 42. In the present embodiment, as an example, the resistor 442 is provided between the gate control circuit 43 and the gate of the semiconductor switch 42, and also functions as a gate resistor. In addition, a diode for preventing the current from the source terminal 413 to the gate control circuit 43 can be provided between the resistor 442 and the source terminal 413.

[0041] Next, the operation when the semiconductor switch 42 cuts off the power supply to the inductive load 2 will be described. When the semiconductor switch 42 cuts off the power supply to the inductive load 2, the inductive load 2 maintains the current by self-induction and causes the current to flow from the source terminal 413 side to the ground side. As a result, the potential of the source terminal 413 drops. The source terminal 413 may also become a negative potential. Thereby, the element voltage applied to the semiconductor switch 42 increases. When the element voltage reaches the clamping voltage Vc, the voltage clamping elements 440(1) to 440(3) clamp the element voltage to the clamping voltage Vc and allow a weak current to flow (refer to the thick dashed arrows in the figure). Thereby, due to the resistors 442 and 443, the gate potential of the semiconductor switch 42 becomes higher than the source potential. As a result, the gate is slightly opened and a weak current flows through the semiconductor switch 42. As a result, the rise of the element voltage of the semiconductor switch 42 is suppressed, preventing its damage. In addition, since only a weak current flows through the semiconductor switch 42, it functions as a resistor and converts electrical energy (= voltage × current × time) into heat. Thereby, if the energy stored in the inductive load 2 is dissipated as heat and the element voltage becomes lower than the clamping voltage Vc, no current flows through the voltage clamping elements 440(1) to 440(3), and the gate of the semiconductor switch 42 becomes closed.

[0042] Next, the operation when the semiconductor switch 42 cuts off the power supply to the inductive load 2 in a state where the voltage clamping terminal 414 is connected to the drain terminal 412 will be described.

[0043] Figure 2 The current path in a state where the voltage clamping terminal 414 is connected to the drain terminal 412 is shown. The thick dashed arrows in the figure indicate the current path.

[0044] If the voltage clamping terminal 414 is connected to the drain terminal 412, in this embodiment, as an example, the voltage clamping element 440(1) is bypassed on the path from the drain terminal 412 to the gate. Therefore, the clamping voltage Vc (= V1 + V2 + V3) is reduced by the amount of the voltage clamping element 440(1) and becomes Vc' (= V2 + V3). Therefore, when the element voltage reaches the clamping voltage Vc' (where Vc' < Vc), the voltage clamping elements 440(1) to 440(3) clamp the element voltage to the clamping voltage Vc' and allow a weak current to flow (refer to the thick dashed arrows in the figure). Thereby, similarly to the above, a weak current flows through the semiconductor switch 42, preventing damage to the semiconductor switch 42, and electrical energy (= voltage × current × time) is converted into heat in the semiconductor switch 42.

[0045] Here, when the clamp voltage is small, the potential difference between the drain terminal 412 and the inductive load 2 becomes smaller than when the clamp voltage is large, so the stored energy of the inductive load 2 is digested as heat energy over a relatively long period of time, and the heat generated in the semiconductor switch 42 is small. Therefore, when the voltage clamp terminal 414 is connected to the drain terminal 412, the processing time of the stored energy of the inductive load 2 becomes longer and the heat generated becomes smaller than when the voltage clamp terminal 414 is not connected to the drain terminal 412.

[0046] According to the semiconductor device 4 described above, the drain terminal 412 is electrically connected to the drain of the semiconductor switch 42 and exposed from the external package 40, and the voltage clamp terminal 414 is electrically connected between the two voltage clamp elements 440 and exposed from the external package 40. Therefore, by connecting or disconnecting the drain terminal 412 and the voltage clamp terminal 414, it is possible to easily change the number of voltage clamp elements 440 on the path from the drain terminal 412 to the gate, and further change the clamp voltage of the clamp circuit 44. Thus, it is possible to easily change the processing time of the stored energy of the inductive load 2 and / or the heat generated by the semiconductor switch 42 due to the energy, depending on the self-inductance of the inductive load 2, the driving method, the heat resistance of the semiconductor switch 42, and the like.

[0047] In addition, the plurality of voltage clamp elements 440 are disposed in the external package 40. Therefore, the clamp voltage can be easily changed without complicating the external circuit of the external package 40.

[0048] Figure 3 The external appearance of the semiconductor device 4 of this embodiment is shown. In this embodiment, as an example, the external package 40 of the semiconductor device 4 has a lead frame 401 on which a semiconductor switch 42 is mounted, and a molded resin portion 402 that seals the semiconductor switch 42 and the lead frame 401. In addition, in this embodiment, as an example, the semiconductor switch 42 is a vertical MOSFET having a gate and a source on the upper surface side and a drain on the lower surface side. Figure 3 Although not shown in the figure, the external package 40 may also cover the upper surface of the semiconductor switch 42 .

[0049] The lead frame 401 may be formed of a metal (copper, for example) having excellent heat dissipation and electrical conductivity. For example, the lead frame 401 may be formed by stamping a metal plate. The lead frame 401 may include a lead frame body 4010 and a plurality of lead frame segments 4011 .

[0050] The lead frame body 4010 may be formed in a rectangular plate shape, and may support the semiconductor switch 42 on the upper surface of the central portion. Solder (not shown) may be provided between the semiconductor switch 42 and the lead frame body 4010 .

[0051] The plurality of lead frame segments 4011 may be formed in a plate shape and arranged separately from each other. As an example, each lead frame segment 4011 may be arranged in the same plane as the lead frame main body 4010 .

[0052] In this embodiment, as an example, the lead frame 401 may have eight lead frame sections 4011 (1) to 4011 (8). Among them, the lead frame sections 4011 (1) and 4011 (4) may be integrated with the drain terminal 412 outside the external package 40, or may be integrated with the lead frame body 4010 inside the external package 40 and connected to the drain on the lower surface of the semiconductor switch 42. The lead frame section 4011 (2) may be integrated with the voltage clamp terminal 414 outside the external package 40, or may be connected between the voltage clamp elements 440 (1) and 440 (2) inside the external package 40. Here, the lead frame section 4011 (2) integrated with the voltage clamp terminal 414 and the lead frame section 4011 (1) integrated with the drain terminal 412 may be connected to each other via a copper wire or the like, and may be arranged adjacent to each other as an example. The lead frame segments 4011(5) and 4011(6) can be integrated with the control terminal 410 and the ground terminal 411 outside the external package 40, or they can be connected to the gate control circuit 43 inside the external package 40. The lead frame segment 4011(8) can be integrated with the source terminal 413 outside the external package 40, or they can be connected to the source of the semiconductor switch 42 inside the external package 40. In addition, the lead frame segments 4011(3) and 4011(7) can be integrated with the NC (No Contact) terminal.

[0053] The molded resin portion 402 molds and seals the semiconductor switch 42 and the lead frame 401. The molded resin portion 402 may be formed of a cured resin. As the resin, an insulating thermosetting resin such as epoxy resin, maleimide resin, polyimide resin, isocyanate resin, amino resin, phenolic resin, silicone resin, etc. may be used, but is not limited thereto. The resin may also contain additives such as inorganic fillers.

[0054] In addition, in the above-mentioned embodiment, the case where the voltage clamp terminal 414 is connected between two adjacent voltage clamp elements 440 is described, but it can also be connected via at least one other voltage clamp element. For example, between the voltage clamp terminal 414 and the node between two voltage clamp elements 440 (as an example, voltage clamp elements 440 (1) and 440 (2)) (also referred to as the connection node of the voltage clamp terminal 414), at least one other voltage clamp element can be provided in a cascade manner. In this case, the difference between the clamp voltages Vc and Vc' that is changed by connecting or disconnecting the drain terminal 412 to the voltage clamp terminal 414 can be easily set. Here, the number of voltage clamp elements 440 located between the connection node of the voltage clamp terminal 414 and the drain terminal 412 can be different from the number of other voltage clamp elements between the voltage clamp terminal 414 and its connection node. As a result, the clamp voltage can be reliably changed by connecting or disconnecting the drain terminal 412 to the voltage clamp terminal 414.

[0055] In addition, the case where the semiconductor device 4 includes one voltage clamp terminal 414 has been described, but it may also include a plurality of voltage clamp terminals 414 connected to a plurality of nodes between the two voltage clamp elements 440. In this case, the clamp voltage can be changed to a plurality of voltages by changing the voltage clamp terminal 414 connected to the drain terminal 412. In addition, by connecting the two voltage clamp terminals 414 to each other, the number of voltage clamp elements 440 on the path from the drain terminal 412 to the gate of the semiconductor switch 42 can be changed, thereby changing the clamp voltage.

[0056] In addition, although the gate control circuit 43 is configured in the external package 40, the gate control circuit 43 may be configured outside the external package 40. In this case, a gate terminal for receiving a control signal from the gate control circuit 43 and supplying the control signal to the gate of the semiconductor switch 42 may be provided in the external package 40. In addition, the semiconductor device 4 may not include the gate control circuit 43.

[0057] The present invention has been described above using embodiments, but the technical scope of the present invention is not limited to the scope described in the above embodiments. It is obvious to those skilled in the art that various changes or improvements can be made to the above embodiments. According to the description of the claims, the forms to which these changes or improvements are made are also included in the technical scope of the present invention.

[0058] It should be noted that the execution order of each process such as actions, sequences, steps and stages in the apparatus, system, program and method shown in the claims, specifications and drawings can be implemented in any order as long as there is no special clear description of "before", "prior to", etc., and the output of the previous process is not used for the subsequent process. Even if the action flow in the claims, specifications and drawings is described using "first", "then", etc. for convenience, it does not mean that it must be implemented in this order.

Claims

1. A semiconductor device, characterized in that: include: Semiconductor switches; An external packaging body, in which the semiconductor switch is built-in; a drain terminal electrically connected to a drain of the semiconductor switch and exposed from the external package; a plurality of voltage clamping elements connected in cascade between the drain terminal and the gate of the semiconductor switch; A gate control circuit, which controls the gate of the semiconductor switch; a source terminal electrically connected to a source of the semiconductor switch and exposed from the external package; a voltage clamp terminal electrically connected between two of the plurality of voltage clamp elements and exposed from the external package body, and capable of switching between a connected state connected to the drain terminal and a disconnected state not connected to the drain terminal; a resistor connected in series between the gate terminal and the source terminal of the semiconductor switch; as well as a resistor disposed between the gate control circuit and the gate of the semiconductor switch, When the voltage clamp terminal is switched to the connection state, one or more of the plurality of voltage clamp elements are bypassed on a path from the drain terminal to the gate.

2. The semiconductor device according to claim 1, wherein: The plurality of voltage clamping elements are disposed in the external package.

3. The semiconductor device according to claim 1 or 2, characterized in that: At least one voltage clamping element is provided in cascade connection between the voltage clamping terminal and a node between the two voltage clamping elements.

4. The semiconductor device according to claim 3, wherein: The number of voltage clamping elements located between the drain terminal and the node among the plurality of voltage clamping elements is different from the number of the at least one voltage clamping element.

5. The semiconductor device according to claim 1 or 2, characterized in that: The semiconductor device includes a plurality of the voltage clamp terminals, and the plurality of the voltage clamp terminals are respectively connected to a plurality of nodes between two voltage clamp elements among the plurality of voltage clamp elements.

6. The semiconductor device according to claim 1 or 2, characterized in that: Each of the plurality of voltage clamping elements is a Zener diode.

7. A device, characterized in that: include: Positive power supply; The semiconductor device according to any one of claims 1 to 6; as well as An inductive load is connected in series with the semiconductor device between the positive power supply and ground.

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