Semiconductor device and power conversion device

Abstract

The emitter main terminal (3) is connected to the emitter electrode surface (12) of the power semiconductor element (1) through a plurality of first bonding wires (15). The emitter reference terminal (4) is connected to the emitter electrode surface (12) of the power semiconductor element (1) through a second bonding wire (16). The degradation site determination unit (9) refers to the corresponding information of the degradation sites in the plurality of junctions (20) between the plurality of first bonding wires (15) and the respectively connected emitter electrode surfaces (12) for the combination of the time change of the first voltage measured by the first voltage measurement circuit (5) and the time change of the second voltage measured by the second voltage measurement circuit (6), which specifies the combination of the time change of the first voltage measured by the first voltage measurement circuit (5) and the time change of the second voltage measured by the second voltage measurement circuit (6).

Description

Technical Field

[0001] The present invention relates to a semiconductor device and a power conversion device. Background Art

[0002] In a power module used in a power conversion device or the like, a plurality of bonding wires are connected to a power semiconductor element.

[0003] For example, a technique for detecting the breakage of a plurality of bonding wires is described in Patent Document 1. In the device of Patent Document 1, a weak current is passed through four first conductive wires to measure the electrical characteristics of the four first conductive wires, and the breakage of the four first conductive wires is detected by comparing the measured electrical characteristics with a reference value.

[0004] Prior art literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2013-206997 Summary of the invention

[0006] However, in Patent Document 1, it is not possible to detect which of the bonding locations between a plurality of bonding wires and a power semiconductor element has deteriorated.

[0007] Therefore, an object of the present invention is to provide a semiconductor device and a power conversion device capable of detecting which of the joints between a plurality of bonding wires and a power semiconductor element has deteriorated.

[0008] The semiconductor device of the present invention comprises: a power semiconductor element; a collector substrate electrically connected to the power semiconductor element; a collector main terminal electrically connected to the collector substrate; an emitter main terminal connected to an emitter electrode surface of the power semiconductor element through a plurality of first bonding wires; an emitter reference terminal connected to the emitter electrode surface of the power semiconductor element through a second bonding wire; a first voltage measuring circuit for measuring a first voltage which is a difference between a potential of the collector main terminal and a potential of the emitter main terminal; a second voltage measuring circuit for measuring a second voltage which is a difference between a potential of the emitter reference terminal and a potential of the emitter main terminal; and a degradation site determination unit for determining a degradation site corresponding to a combination of a time change of the first voltage measured by the first voltage measurement circuit and a time change of the second voltage measured by the second voltage measurement circuit, with reference to correspondence information of degradation sites among a plurality of junctions between the plurality of first bonding wires and the respectively connected emitter electrode surfaces, which specifies a combination of a time change of the first voltage and a time change of the second voltage.

[0009] According to the present invention, it is possible to detect which of the joints between a plurality of bonding wires and a power semiconductor element have experienced degradation by referring to corresponding information, wherein the corresponding information specifies the degraded locations among the plurality of joints between the plurality of first bonding wires and the respectively connected emitter electrode surfaces for a combination of a time change of a first voltage and a time change of a second voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a diagram showing a schematic structure of a semiconductor device according to the first embodiment.

[0011] Figure 2 is a schematic diagram showing a cross section of a power module included in a semiconductor device.

[0012] Figure 3 It is a perspective view showing the connection status between the power semiconductor element 1 and the surrounding members.

[0013] Figure 4 This is a diagram showing a part of the direction in which the main current flows and the magnitude of the main current.

[0014] Figure 5 It is a diagram for explaining the distance between a degraded bonding portion and a connection portion of the second bonding wire 16 .

[0015] Figure 6 1 is a diagram showing an example of the correspondence relationship between the first deteriorated location and a combination of the time change ΔVce of the first voltage Vce and the time change ΔVee of the second voltage Vee.

[0016] Figure 7 FIG. 1 is a diagram showing an example of a lookup table for first identifying a degraded location.

[0017] Figure 8 This is a diagram showing the structure of a semiconductor device according to a second embodiment.

[0018] Fig. 9 1 is a diagram showing the correspondence relationship between the second degraded portion and the combination of the time change of the first voltage Vce and the time change of the second voltage Vee when the first degraded portion is the junction portion 20A.

[0019] Fig.10 1 is a diagram showing a lookup table for specifying a second degraded portion when the first degraded portion is the joint portion 20A.

[0020] Fig.11 This is a diagram showing the structure of a semiconductor device according to a third embodiment.

[0021] Fig.12This is a diagram showing the structure of a semiconductor device according to a fourth embodiment.

[0022] Fig.13 : is a graph which shows the relationship between the collector current Ic and the first voltage Vce in the IGBT.

[0023] Fig.14 1 is a diagram for explaining correction of the first voltage Vce at the (n-1) time point before the current time point n.

[0024] Fig.15 3 is a diagram for explaining correction of the first voltage Vce at the current time point n.

[0025] Fig.16 : is a graph which shows the relationship between the collector current Ic and the second voltage Vee in the IGBT.

[0026] Fig.17 It is a diagram for explaining correction of the second voltage Vee at the (n-1) time point.

[0027] Fig.18 : is a diagram for explaining correction of the second voltage Vee at time point n.

[0028] Fig.19 1 is a diagram showing the relationship between the collector current Ic and the second voltage Vee at three temperatures Tk of the power semiconductor element 1 .

[0029] Fig. 20 This is a diagram showing the structure of a semiconductor device according to a fifth embodiment.

[0030] Fig.21 This is a flowchart showing the process of estimating the temperature of the power semiconductor element 1 and identifying the deteriorated portion according to the fifth embodiment.

[0031] Fig. 22 : is a graph showing the time change of the standard voltage Vee0.

[0032] Fig.23 This is a diagram showing the structure of a semiconductor device according to a sixth embodiment.

[0033] Fig.24 This is a flowchart showing the process of estimating the temperature of the power semiconductor element 1 and identifying the deteriorated portion according to the sixth embodiment.

[0034] Fig.25 This is a block diagram showing the configuration of a power conversion system according to a seventh embodiment.

[0035] Fig.26 This is a diagram showing a specific configuration of the degradation monitoring unit 205 according to the first to sixth embodiments.

[0036] Fig. 27 1 is a diagram showing an example in which the processing circuit 1001 is realized by software.

[0037] Fig.28 2 is a diagram showing another example of the correspondence relationship between the first degraded location and the combination of the time change ΔVce of the first voltage Vce and the time change ΔVce of the second voltage Vee.

[0038] Fig.29 FIG. 2 is a diagram showing another example of the lookup table for specifying the first degraded location.

[0039] (Explanation of symbols)

[0040] 1: power semiconductor element; 2: collector main terminal; 3: emitter main terminal; 4: emitter reference terminal; 5: first voltage measurement circuit; 6: second voltage measurement circuit; 7: first output terminal; 8: second output terminal; 9: deterioration location determination unit; 10: third output terminal; 11: collector substrate; 12: emitter electrode surface; 13: solder; 14: third bonding wire; 15, 15A to 15D: first bonding wire; 16: second bonding wire; 17: main current path; 18: heat generation; 19: lookup table storage unit; 20A to 20D : Joint part; 21: Gate terminal; 22: Gate bonding wire; 23: Deterioration part history recording unit; 25: Life estimation unit; 27: Temperature sensor; 31: Voltage history recording unit; 32, 132: Temperature estimation unit; 100: Power supply; 119: Deterioration part; 131: Resistance history recording unit; 200: Power conversion device; 201: Main conversion circuit; 202: Semiconductor module; 203: Control circuit; 205: Deterioration monitoring unit; 300: Load; 1001: Processing circuit; 1002: Processor; 1003: Memory. DETAILED DESCRIPTION

[0041] Hereinafter, embodiments will be described with reference to the drawings.

[0042] Implementation method 1.

[0043] Figure 1 This is a diagram showing a schematic structure of a semiconductor device according to the first embodiment.

[0044] The semiconductor device includes a power semiconductor element 1 , a collector main terminal 2 , an emitter main terminal 3 , an emitter reference terminal 4 , and a degradation monitoring unit 205 .

[0045] The degradation monitoring unit 205 includes a first voltage measurement circuit 5 , a second voltage measurement circuit 6 , a lookup table storage unit 19 , a degradation location identification unit 9 , a first output terminal 7 , a second output terminal 8 , and a third output terminal 10 .

[0046] The power semiconductor element 1 is constituted by, for example, an IGBT (Insulated Gate Bipolar Transistor) and is connected to a collector main terminal 2 , an emitter main terminal 3 , and an emitter reference terminal 4 .

[0047] The first voltage measurement circuit 5 is connected between the collector main terminal 2 and the emitter main terminal 3 , and outputs information indicating a first voltage Vce, which is a difference between the potential of the collector main terminal 2 and the potential of the emitter main terminal 3 , to the first output terminal 7 .

[0048] The second voltage measurement circuit 6 is connected between the emitter reference terminal 4 and the emitter main terminal 3 . The second voltage measurement circuit 6 outputs information indicating a second voltage Vee, which is a difference between the potential of the emitter reference terminal 4 and the potential of the emitter main terminal 3 , to the second output terminal 8 .

[0049] The lookup table storage unit 19 stores the lookup table. The degradation location identification unit 9 refers to the corresponding information in the lookup table to identify the degradation location corresponding to the combination of the time change ΔVce of the first voltage measured by the first voltage measurement circuit 5 and the time change ΔVee of the second voltage measured by the second voltage measurement circuit 6. The degradation location identification unit 9 outputs information indicating the identified degradation location to the third output terminal 10.

[0050] Hereinafter, how the deteriorated location identifying unit 9 identifies the deteriorated location will be described based on the operation of the power semiconductor device 1 .

[0051] Figure 2 is a schematic diagram showing a cross section of a power module included in a semiconductor device.

[0052] The power module includes a power semiconductor element 1, a collector substrate 11, solder 13, a collector main terminal 2, an emitter main terminal 3, an emitter reference terminal 4, an emitter side main current bonding wire (hereinafter referred to as the first bonding wire) 15, an emitter reference bonding wire (hereinafter referred to as the second bonding wire) 16 and a collector side main current bonding wire (hereinafter referred to as the third bonding wire) 14.

[0053] The power semiconductor element 1 is bonded to the collector substrate 11 by solder 13. In the power semiconductor element 1, the surface facing the collector substrate 11 functions as a collector, and the surface opposite to the surface functions as an emitter. The surface that functions as an emitter is an emitter electrode surface 12. A layer of a highly conductive metal such as aluminum or copper is formed on the surface of the emitter electrode surface 12.

[0054] The collector main terminal 2, the emitter main terminal 3, and the emitter reference terminal 4 are connected to the power semiconductor element 1 through a plurality of bonding wires 14, 15, and 16. That is, the collector main terminal 2 is connected to the collector substrate 11 through the third bonding wire 14. The emitter main terminal 3 is connected to the emitter electrode surface 12 through the first bonding wire 15. The emitter reference terminal 4 is connected to the emitter electrode surface 12 through the second bonding wire 16.

[0055] By applying ultrasonic waves to the bonding portions between the bonding wires 14 , 15 , and 16 and the metal of the other party and pressing them, the bonding portions are firmly bonded to the metal of the other party.

[0056] In addition, the life of the power module is generally determined by the life of the bonding parts of these bonding wires 14, 15, 16. That is, the following phenomenon occurs first: the bonding parts between the bonding wires 14, 15, 16 and the metal on the other side deteriorate, resulting in the separation of the bonding parts. The life of the power semiconductor element 1 itself, the life of the material of the bonding wires 14, 15, 16, and the life of the material of the metal constituting the collector main terminal 2, the emitter main terminal 3, and the emitter reference terminal 4 are much longer than the life of the bonding parts between the bonding wires 14, 15, 16 and the metal on the other side.

[0057] The life of the solder 13 joining the power semiconductor element 1 and the collector substrate 11 is shorter than the life of the above materials, but longer than the life of the joints between the bonding wires 14, 15, and 16 and the metal of the other party. The reason is described below.

[0058] exist Figure 2 1 shows a path 17 of a main current flowing from the collector main terminal 2 to the emitter main terminal 3. The main current passes through the collector main terminal 2, the third bonding wire 14, the collector substrate 11, the solder 13, the power semiconductor element 1, the first bonding wire 15, and the emitter main terminal 3 in this order.

[0059] The part of the main current path 17 where heat is generated is the power semiconductor element 1. Unlike other components, the power semiconductor element 1 changes its resistance value due to gate control, thereby turning the main current on / off. The power semiconductor element 1 has a low resistance, so the power semiconductor element 1 has the following characteristics. When the power semiconductor element 1 cuts off the current, a high voltage is applied to the power semiconductor element 1, but no current flows through the power semiconductor element 1. When the current flows through the power semiconductor element 1, a large current flows through the power semiconductor element 1, but almost no voltage is applied to the power semiconductor element 1. In other words, the power semiconductor element 1 consumes almost no electricity when the current is cut off and when the power is turned on. However, when switching, both current and voltage are generated, so the heat generated by the power semiconductor element 1 increases when switching. This heat only occurs when switching, so if the frequency of switching is reduced, the heat is less. However, the power semiconductor element 1 is usually switched at a high frequency of more than several kHz, so instantaneous heat is repeated at a very high frequency. In Figure 2 Heat generation 18 is shown.

[0060] The power semiconductor element 1 repeatedly generates heat at a high frequency, and thus stress caused by heat is repeatedly applied to the components connected to the power semiconductor element 1. As a result, the connected components are degraded. The collector substrate 11 is bonded to the collector side of the power semiconductor element 1 via the solder 13, and the first bonding wire 15 is bonded to the emitter side of the power semiconductor element 1, that is, the surface of the emitter electrode surface 12. Therefore, stress caused by heat is applied to the solder 13 and the first bonding wire 15.

[0061] exist Figure 2 1 shows a site 119 in the solder 13 where degradation may occur due to heat 18 of the power semiconductor element 1. Also shown is a site 20 in the junction between the first bonding wire 15 and the emitter electrode surface 12 where degradation may occur due to heat 18.

[0062] The solder 13 is connected to the entire surface of the collector side of the power semiconductor element 1. On the other hand, the area of ​​the joint portion between the first bonding wire 15 and the emitter electrode surface 12 is equal to the cross-sectional area of ​​the first bonding wire 15 or is within several times the cross-sectional area of ​​the first bonding wire 15. That is, with respect to the current density, the joint portion of the first bonding wire 15 is larger than the solder 13. Therefore, in addition to the electromigration effect caused by the high current density, the joint portion 20 of the first bonding wire 15 reaches the end of its life first.

[0063] Therefore, generally, estimating the life of a semiconductor device means estimating the life of a junction 20 between the first bonding wire 15 and the emitter electrode surface 12. In an actual semiconductor device, a plurality of first bonding wires 15 are bonded to the power semiconductor element 1. For example, more than ten first bonding wires 15 may be bonded to the power semiconductor element 1.

[0064] Figure 3 It is a perspective view showing the connection state between the power semiconductor element 1 and the surrounding members. Here, four first bonding wires 15A to 15D are bonded to the power semiconductor element 1 at bonding locations 20A to 20D.

[0065] If some of the plurality of joints 20A to 20D degrade, the performance of the semiconductor device is reduced, but there are cases where the semiconductor device can continue to operate. When some of the plurality of joints 20A to 20D degrade, the criteria for judging that the semiconductor device has reached the end of its life vary depending on the purpose of use of the semiconductor device. When some of the plurality of joints 20A to 20D degrade, the semiconductor device may be judged to have reached the end of its life immediately, or it may be judged to have reached the end of its life after a predetermined number or more of the plurality of joints 20A to 20D degrade.

[0066] like Figure 3 As shown, in the case where a plurality of bonding wires 15A to 15D are configured, estimating the life of the semiconductor device means determining to what extent the current degradation state of the power module is in relation to the degradation state considered to be the limit of the life of the semiconductor device, thereby determining how long the power module can be used until the limit degradation state is reached.

[0067] If the accuracy of determining the degradation state of the power module is improved, the replacement of the power module can be set at an appropriate time. If the accuracy of determining the degradation state of the power module is reduced, the semiconductor device may suddenly reach the end of its life at an unexpected time, which may hinder the business of the user of the power conversion device.

[0068] In order to accurately determine the degradation status of the power module, it is necessary to accurately detect the degradation of the bonding parts 20A to 20D of the first bonding wire 15. However, in the previous technology, the accuracy of degradation detection is limited. The reason is that it is impossible to detect which bonding part among the bonding parts 20A to 20D of the plurality of first bonding wires 15A to 15D has degraded. In the prior art, although it is possible to detect the degradation of the plurality of bonding wires as a whole, it is impossible to detect the degradation of each bonding wire.

[0069] When a plurality of first bonding wires 15 are arranged, the order of degradation of the plurality of first bonding wires 15 is not necessarily fixed. The order of degradation of the plurality of first bonding wires 15 may differ depending on the usage conditions, that is, the driving method of the power semiconductor element 1 .

[0070] For example, in the first driving method, sometimes the first bonding part 20C or the bonding part 20D degrades, and after a short time, the bonding part 20D or the bonding part 20C degrades. In this case, half of the remaining first bonding wires 15 degrade in a short period of time from the initial degradation. On the other hand, in the second driving method, sometimes the bonding part 20A or the bonding part 20B degrades first, and after a long time, the bonding part 20B or the bonding part 20A degrades. In such a case, by only detecting that only one of the four first bonding wires 15A to 15D has degraded, the life of the semiconductor device cannot be accurately estimated. When half of the first bonding wires have degraded, even if it is determined that the life of the semiconductor device has expired, there is a difference in the length of the period until the subsequent life when the first degradation occurs in the bonding part 20C and the bonding part 20A.

[0071] Conventionally, it is necessary to conduct a process such as passing a current through each bonding wire individually by some method to check the resistance value. That is, it is impossible to detect the degradation of an individual bonding wire without using a high-cost device and a complicated inspection method.

[0072] In the present embodiment, it is possible to identify which of the bonding portions between the plurality of first bonding wires 15 and the emitter electrode surface 12 of the power semiconductor element 1 has deteriorated without using a special device. This principle will be described in detail below.

[0073] The first voltage Vce is the difference between the potential of the collector main terminal 2 and the potential of the emitter main terminal 3. The first voltage Vce is the voltage between the collector main terminal 2 and the emitter main terminal 3 that the power module has from the beginning. Therefore, the first voltage Vce can be measured without adding a special structure to the power module. The first voltage Vce is measured while the power semiconductor element 1 is energized. The power semiconductor element 1 is connected in series to the joint 20 of the first bonding wire 15 between the collector main terminal 2 and the emitter main terminal 3. Therefore, the magnitude of the first voltage Vce is greater than the sum of the magnitude of the voltage generated by the resistance of the power semiconductor element 1 and the magnitude of the voltage generated by the joint 20 of the first bonding wire 15.

[0074] The second voltage Vee is the difference between the potential of the emitter reference terminal 4 and the potential of the emitter main terminal 3. The second voltage Vee is the voltage between the emitter main terminal and the emitter reference terminal 4 that the power module has from the beginning. The gate terminal 21 is connected to the gate of the power semiconductor element 1 through the gate bonding wire 22. The emitter reference terminal 4 is used to provide a reference potential that serves as a reference for the voltage applied to the gate terminal 21. This reference potential is required to be equal to the potential of the emitter electrode surface 12. Therefore, the emitter reference terminal 4 is connected to the emitter electrode surface 12 through the second bonding wire 16. The emitter main terminal 3 cannot be used to provide the reference potential. This is because the main current generated by the energization of the power semiconductor element 1 generates a voltage drop due to the resistance of the path from the emitter electrode surface 12 to the emitter main terminal 3, so the potential of the emitter main terminal 3 does not accurately reflect the potential of the emitter electrode surface 12. Since the main current does not flow through the emitter reference terminal 4 and the second bonding wire 16, there is almost no difference between the potential of the emitter reference terminal 4 and the potential of the emitter electrode surface 12. Therefore, the emitter reference terminal 4 can provide an accurate reference potential.

[0075] In addition, since a current with a high current density does not flow through the second bonding wire 16, electromigration does not occur. Generally, the second bonding wire 16 is connected near the periphery where the temperature of the power semiconductor element 1 tends to drop. As a result, the degradation of the second bonding wire 16 is not easy to progress. In addition, in order to ensure redundancy, a plurality of second bonding wires 16 are sometimes provided.

[0076] Since the power semiconductor element 1 itself is not included in the path of the second voltage Vee, the resistance value of the power semiconductor element 1 does not affect the magnitude of the second voltage Vee. Although the second voltage Vee is regarded as the potential difference between the emitter electrode surface 12 and the emitter main terminal 3, strictly speaking, they are not the same. This will be described later.

[0077] Next, the principle of generating the first voltage Vce will be described.

[0078] As described above, the magnitude of the first voltage Vce is greater than or equal to the sum of the magnitude of the voltage generated by the resistance of the power semiconductor element 1 and the magnitude of the voltage generated by the bonding portion 20 of the first bonding wire 15. However, the first voltage Vce is affected not only by the resistance of the first bonding wire 15 but also by the resistance caused by the current flowing inside the emitter electrode surface 12.

[0079] Figure 4: is a diagram showing a part of the direction in which the main current flows and the magnitude of the main current. The main current flows from the collector to the emitter, so the main current flows from the collector substrate 11 into the power semiconductor element 1, flows out to the emitter electrode surface 12 of the power semiconductor element 1, and then flows through the first bonding wires 15A to 15D to flow through the emitter main terminal 3. At this time, the current flowing through the first bonding wires 15A to 15D is not uniform. For example, a part of the current flowing out directly below the junction 20A proceeds along a path that passes through the first bonding wire 15A and flows out to the emitter main terminal 3. The remaining part of the current flowing out directly below the junction 20A proceeds along a path that passes through the first bonding wire 15C and flows to the junction 20C after passing through the emitter electrode surface 12. On the other hand, the current flowing out directly below the junction 20C mainly proceeds along a path that passes through the first bonding wire 15C and flows to the emitter main terminal 3. This is because the other paths are long and therefore have large resistance values.

[0080] As a result, for example, even if the junction 20A deteriorates and the first bonding wire 15A stops being energized, the impact is relatively small. Even if the current flowing out to the junction 20A does not pass through the first bonding wire 15A, it can flow out from the junction 20C through the first bonding wire 15C to the emitter main terminal 3 at a relatively low cost. In contrast, when the junction 20C deteriorates and the first bonding wire 15C stops being energized, the impact is relatively large. This is because the current flowing out from the junction 20C through the first bonding wire 15C directly to the emitter main terminal 3 must flow from other junctions to the emitter main terminal 3 through a path with a larger resistance.

[0081] That is, when the bonding portion 20A of the first bonding wire 15A degrades, the increase in the first voltage Vce generated is relatively small. On the other hand, when the bonding portion 20C of the first bonding wire 15C degrades, the increase in the first voltage Vce generated is relatively large. For example, when the bonding portion 20A degrades first, the first voltage Vce increases by 20%, but when the bonding portion 20C degrades first, the first voltage Vce increases by 30%.

[0082] However, it is not possible to identify the degraded bonding part of the first bonding wires 15A to 15D based only on the time variation of the first voltage Vce. This is because, when a large number of first bonding wires 15A to 15D are arranged, there may be other first bonding wires with the same conditions. For example, when the bonding part 20B is degraded first, the first voltage Vce may increase by 20%, and when the bonding part 20D is degraded first, the first voltage Vce may increase by 30%. Therefore, it is not possible to identify the degraded bonding part based only on the first voltage Vce.

[0083] Next, the second voltage Vee will be described.

[0084] The second voltage Vee is the difference between the potential of the emitter reference terminal 4 and the potential of the emitter main terminal 3, so it is often considered to be a voltage reflecting the resistance value of the first bonding wires 15A to 15D, but it is not only that. It can be said that a metal layer is formed on the surface of the emitter electrode surface 12 of the power semiconductor element 1, which has a resistance component. As described above, the current flows in the emitter electrode surface 12, so the second voltage Vee also reflects the potential difference caused by the resistance component. If we look at it from another angle, it can also be said that the potential of the emitter reference terminal 4 is roughly equal to the potential of the emitter main terminal 3 because the emitter reference terminal 4 and the emitter main terminal 3 are connected by the first bonding wire 15. In other words, if there is no first bonding wire 15, the voltage between the emitter reference terminal 4 and the emitter main terminal 3 may become larger. Therefore, the influence of the degradation of the first bonding wire 15 on the second voltage Vee strongly depends on how close the bonding part of the second bonding wire 16 is to the degraded part among the bonding parts 20A to 25D of the first bonding wire.

[0085] Figure 5 1 is a diagram for explaining the distance between the degraded bonding portion and the connection portion of the second bonding wire 16. Figure 5 In FIG. 1 , the difference in distance between the degraded bonding portion and the connection portion of the second bonding wire 16 is indicated by arrows.

[0086] The bonding portion 20B of the first bonding wire 15B is close to the connection portion between the second bonding wire 16 and the emitter electrode surface 12. The bonding portion 20A of the first bonding wire 15A is far from the connection portion between the second bonding wire 16 and the emitter electrode surface 12. In the case where the bonding portion 20B is initially degraded, the second voltage Vee rises significantly, but in the case where the bonding portion 20A is initially degraded, the second voltage Vee does not rise significantly. That is, the rise value of the second voltage Vee will be different depending on the bonding portion of the first bonding wire 15 that has been degraded. For example, in the case where the bonding portion 20B is initially degraded, the second voltage Vee will rise by 40%, and in the case where the bonding portion 20A is initially degraded, the second voltage Vee will only rise by 10%.

[0087] However, when there are a large number of first bonding wires 15, there may be other first bonding wires 15 with the same conditions. Figure 4 In the case of , the second voltage Vee also increases by 40% when the bonding portion 20D degrades first, and also increases by 10% when the bonding portion 20C degrades first. The bonding portion that has degraded cannot be identified based on the second voltage Vee alone.

[0088] The present embodiment is different from the conventional technology in that the degradation monitoring unit 205 of the present embodiment measures the first voltage Vce and the second voltage Vee in consideration of the properties of the power semiconductor element 1 as described above, and identifies the degradation location based on their temporal changes.

[0089] Figure 6 1 is a diagram showing an example of the correspondence relationship between the first deteriorated location and a combination of the time change ΔVce of the first voltage Vce and the time change ΔVce of the second voltage Vee.

[0090] When the first degraded portion is the joint 20A, the first voltage Vce increases by 20%±ΔV2, and the second voltage Vee increases by 10%±ΔV1. When the first degraded portion is the joint 20B, the first voltage Vce increases by 20%±ΔV2, and the second voltage Vee increases by 40%±ΔV4. When the first degraded portion is the joint 20C, the first voltage Vce increases by 30%±ΔV3, and the second voltage Vee increases by 10%±ΔV1. When the first degraded portion is the joint 20D, the first voltage Vce increases by 30%±ΔV3, and the second voltage Vee increases by 40%±ΔV4. For example, ΔV1 is 1%, ΔV2 is 2%, and ΔV3 is 3%. ΔV4 is 4%.

[0091] Figure 7FIG. 1 is a diagram showing an example of a lookup table for identifying the first deteriorated part. Figure 6 The query table is derived based on the corresponding relationship.

[0092] The lookup table includes correspondence information that specifies deteriorated locations among a plurality of junctions between the plurality of first bonding wires 15 and the emitter electrode surfaces 12 connected thereto, respectively, for a combination of the time change ΔVce of the first voltage and the time change ΔVee of the second voltage.

[0093] like Figure 7 As shown, it is stipulated that when the first voltage Vce increases by 20%±ΔV2 and the second voltage Vee increases by 10%±ΔV1, the first degraded portion is the junction portion 20A. It is stipulated that when the first voltage Vce increases by 20%±ΔV2 and the second voltage Vee increases by 40%±ΔV4, the first degraded portion is the junction portion 20B. It is stipulated that when the first voltage Vce increases by 30%±ΔV3 and the second voltage Vee increases by 10%±ΔV1, the first degraded portion is the junction portion 20C. It is stipulated that when the first voltage Vce increases by 30%±ΔV3 and the second voltage Vee increases by 40%±ΔV4, the first degraded portion is the junction portion 20D.

[0094] The degradation location identification unit 9 calculates the time change ΔVce between the first voltage Vce(n) at the current time point n and the first voltage Vce(n-1) at the previous time point (n-1) as shown in the following equation (1). The degradation location identification unit 9 calculates the time change ΔVee between the second voltage Vee(n) at the current time point n and the second voltage Vee(n-1) at the previous time point (n-1) as shown in the following equation (2).

[0095] ΔVce=Vce(n)-Vce(n-1)…(1)

[0096] ΔVee=Vee(n)-Vee(n-1)…(2)

[0097] Alternatively, the degradation location identification unit 9 may calculate the time change ΔVce between the first voltage Vce(n) at the current time point n and the first voltage Vce(n-1) at the previous time point (n-1) as shown in the following formula (1A). The degradation location identification unit 9 may also calculate the time change ΔVee between the second voltage Vee(n) at the current time point n and the second voltage Vee(n-1) at the previous time point (n-1) as shown in the following formula (2A).

[0098] ΔVce={Vce(n)-Vce(n-1)} / Vce(n-1) ...(1A)

[0099] ΔVee={Vee(n)-Vee(n-1)} / Vee(n-1) ...(2A)

[0100] The degradation location identification unit 9 refers to the lookup table to identify the degradation location corresponding to the combination of the time change ΔVce of the first voltage Vce and the time change ΔVce of the second voltage Vee. If the combination of the time change ΔVce of the first voltage Vce and the time change ΔVce of the second voltage Vee is not included in the lookup table, the degradation location identification unit 9 determines that there is no degradation location in the plurality of junctions between the plurality of first bonding wires 15 and the emitter electrode surfaces 12 respectively connected thereto.

[0101] As described above, according to the semiconductor device of the first embodiment, without adding a special structure, it is possible to detect which of the bonding portions between the plurality of first bonding wires 15 and the power semiconductor element 1 has deteriorated by measuring the voltage between the existing two terminals and referring to the pre-stored lookup table. As a result, the life of the semiconductor device can be estimated with good accuracy.

[0102] Implementation method 2.

[0103] When there are a large number of first bonding wires, the order in which the bonding parts of the first bonding wires deteriorate may change depending on the usage and load conditions of the power module, that is, the driving method. Sometimes, by using the history of the bonding parts that have deteriorated, the next deteriorated part can be estimated with high accuracy. Embodiment 2 uses a lookup table corresponding to the history of the bonding parts that have deteriorated.

[0104] Figure 8 1 is a diagram showing a structure of a semiconductor device according to Embodiment 2. The semiconductor device according to Embodiment 2 includes a deteriorated portion history recording unit 23 in addition to the structural elements of the semiconductor device according to Embodiment 1.

[0105] The degraded portion history recording unit 23 records the history of the bonding portion of the first bonding wire where degradation has occurred.

[0106] When any of the plurality of joints is not degraded, the degraded portion identifying unit 9 refers to Figure 7 The degraded part identifying unit 9 identifies the degraded part by referring to the lookup table corresponding to the degraded part when any of the plurality of joint parts is degraded.

[0107] Fig. 9 1 is a diagram showing the correspondence relationship between the second degraded portion and the combination of the time change of the first voltage Vce and the time change of the second voltage Vee when the first degraded portion is the junction portion 20A.

[0108] When the second degraded portion is the junction 20B, the first voltage Vce increases by 40% ± ΔV4, and the second voltage Vee increases by 80% ± ΔV8. When the second degraded portion is the junction 20C, the first voltage Vce increases by 60% ± ΔV6, and the second voltage Vee increases by 20% ± ΔV2. When the second degraded portion is the junction 20D, the first voltage Vce increases by 60% ± ΔV6, and the second voltage Vee increases by 80% ± ΔV8. For example, ΔV2 is 2%, ΔV4 is 4%, and ΔV6 is 6%. ΔV8 is 8%.

[0109] Fig.10 FIG. 2 is a diagram showing a lookup table for determining a second deteriorated portion when the first deteriorated portion is the joint portion 20A. Fig. 9 The query table is derived based on the corresponding relationship.

[0110] It is stipulated that when the first voltage Vce increases by 40%±ΔV4 and the second voltage Vee increases by 80%±ΔV8, the second degraded portion is the junction portion 20B. It is stipulated that when the first voltage Vce increases by 60%±ΔV6 and the second voltage Vee increases by 20%±ΔV2, the second degraded portion is the junction portion 20C. It is stipulated that when the first voltage Vce increases by 60%±ΔV6 and the second voltage Vee increases by 80%±ΔV8, the second degraded portion is the junction portion 20D.

[0111] When the first degraded portion is the joint portion 20A, the degraded portion identifying unit 9 refers to Fig.10 Similarly, when the first degraded part is the joint part 20B, 20C, or 20D, the degraded part identifying unit 9 determines the second degraded part corresponding to the measured ΔVce and ΔVee by referring to the lookup tables corresponding to 20B, 20C, or 20D, respectively.

[0112] The degraded location identification unit 9 may identify the i-th degraded location by referring to the i-th degraded location identification lookup table corresponding to the first to (i-1)-th degraded locations.

[0113] As described above, according to the present embodiment, the next degraded portion can be identified based on the history of the degraded portion.

[0114] Implementation method 3.

[0115] The semiconductor device of the third embodiment proposes estimation of the life of the semiconductor device and change of the driving method based on the history of the junction portion where degradation has occurred and the driving method during use.

[0116] Fig.111 is a diagram showing a structure of a semiconductor device according to Embodiment 3. The semiconductor device according to Embodiment 3 includes a lifetime estimation unit 25 in addition to the components of the semiconductor device according to Embodiment 2.

[0117] The degraded portion history outputted from the degraded portion history recording unit 23 is sent to the life estimating unit 25. The life estimating unit 25 estimates the life of the semiconductor device due to the current driving method based on the history of the degraded junction portion and the driving method of the power semiconductor element 1.

[0118] The driving method is represented by a combination of conditions for switching the power semiconductor element 1. Specifically, the driving method includes a collector voltage, a collector current, a gate voltage, a gate current, a switching frequency, and the like applied to the power semiconductor element 1.

[0119] As described below, the life of a semiconductor device may vary depending on the driving method.

[0120] In driving method A, although the power efficiency is high, the electromagnetic noise also becomes larger. When driving method A is used, one of the joints 20C or 20D is first degraded. And, when one of the joints 20C or 20D is degraded, after a short time, the other of the joints 20C or 20D is degraded, and the semiconductor device reaches the end of its life. In driving method B, although the power efficiency is slightly worse, the electromagnetic noise is less. When driving method B is used, one of the joints 20A or 20B is first degraded. And, when one of the joints 20A or 20B is degraded, after a long time, the other of the joints 20A or 20B is degraded, and the semiconductor device reaches the end of its life.

[0121] For example, when the “driving method A” is continuously used from the beginning and the degradation of the bonding portion 20C of the first bonding wire 15C is detected after 10,000 hours, for example, half of the bonding portion of the first bonding wire 15 is degraded after a further 100 hours due to the use of the driving method A, and the life estimation unit 25 estimates that the semiconductor device has reached the end of its life. Alternatively, when the “driving method B” is continuously used from the beginning and the degradation of the bonding portion 20A of the first bonding wire 15D is detected after 10,000 hours, for example, half of the bonding portion of the first bonding wire 15 is degraded after a further 1,000 hours due to the use of the driving method B, and the life estimation unit 25 estimates that the semiconductor device has reached the end of its life.

[0122] In this way, the history of a degraded portion among a plurality of bonding portions may be related to the degradation rate in the future. Therefore, by utilizing this fact, the accuracy of prediction of the life of the semiconductor device can be improved.

[0123] For example, when degradation of the joint 20C or 20D is first detected using the driving method A, the life estimation unit 25 recommends switching to the driving method B which takes longer until the end of the life.

[0124] The life estimation unit 25 can also be configured to automatically switch to a driving method that has a longer life together with a control circuit (not shown). For example, when the degradation of the joint 20C or 20D is initially detected using the driving method A, the life estimation unit 25 instructs the control circuit to switch to the driving method B, and the control circuit controls the switch to the driving method B.

[0125] As described above, according to the semiconductor device of the third embodiment, it is possible to estimate the life of the semiconductor device and suggest a driving method for prolonging the life based on the history of the deteriorated portion and the driving method of the power semiconductor element.

[0126] Implementation method 4.

[0127] Fig.12 1 is a diagram showing a structure of a semiconductor device according to Embodiment 4. The semiconductor device according to Embodiment 4 includes a temperature sensor 27 in addition to the components of the semiconductor device according to Embodiment 1.

[0128] The temperature sensor 27 measures the temperature Tk of the power semiconductor element 1. The temperature sensor 27 may be a different element from a thermistor or a thermocouple, or may be a temperature detection diode or the like integrally built into the power semiconductor element 1.

[0129] Fig.13 : is a graph showing the relationship between the collector current Ic and the first voltage Vce in the IGBT.

[0130] The first voltage Vce changes according to the collector current Ic and the temperature Tk of the power semiconductor element 1 .

[0131] Even when the same collector current Ic is supplied to the power semiconductor element 1, the resistance value of the power semiconductor element 1 changes according to the temperature Tk of the power semiconductor element 1. As a result, for example, the first voltage Vce generated at 25°C and the first voltage Vce generated at 125°C have different values.

[0132] Therefore, even if the degradation degree of the first bonding wire 15 does not change at all, the value of the first voltage Vce will change according to the temperature Tk of the power semiconductor element 1. If this is not taken into consideration, the first bonding wire 15 may be mistakenly judged to be degraded even though it is not degraded. Fig.13 As shown, in a certain temperature range, there is a collector current Ic_nd in which the first voltage Vce does not change even if the temperature Tk of the power semiconductor element 1 changes. When the temperature Tk of the power semiconductor element 1 is 25°C to 125°C, the first voltage Vce measured at the collector current Ic_nd becomes Vce_nd, which is a constant value, and thus the change of the temperature Tk of the power semiconductor element 1 can be avoided. However, when the temperature Tk of the power semiconductor element 1 exceeds the temperature range (25°C to 125°C), the first voltage Vce measured at the collector current Ic_nd may not become Vce_nd.

[0133] In the first embodiment, Fig.10 The lookup table defines the deteriorated portion of the bonding portion between the power semiconductor element 1 and the first bonding wire corresponding to the change ΔVce of the first voltage and the change ΔVee of the second voltage when the temperature Tk of the power semiconductor element 1 is the standard temperature (25°C). Therefore, when the temperature Tk of the power semiconductor element 1 is different from the standard temperature, in order to use the lookup table, it is necessary to correct the change ΔVce of the first voltage and the change ΔVee of the second voltage.

[0134] In the present embodiment, the deteriorated location identification unit 9 corrects the time variation ΔVce of the first voltage Vce based on the temperature Tk of the power semiconductor element 1 .

[0135] Fig.14 1 is a diagram for explaining correction of the first voltage Vce at the (n-1) time point before the current time point n.

[0136] When the temperature Tk of the power semiconductor element 1 is 125°C and the first voltage Vce is Vce(n-1,125°C) at the time point (n-1), the degradation location identification unit 9 determines that Fig.14 As shown, under the condition that the collector current Ic is the same, the first voltage Vce (n-1, 25° C.) is obtained when the temperature Tk of the power semiconductor element 1 is 25° C.

[0137] Fig.15 3 is a diagram for explaining correction of the first voltage Vce at the current time point n.

[0138] When the temperature Tk of the power semiconductor element 1 is 75° C. and the first voltage Vce is Vce(n,75° C.) at time point n, the degradation location identification unit 9 determines that Fig.15 As shown, under the condition that the collector current Ic is the same, the first voltage Vce (n, 25° C.) is obtained when the temperature Tk of the power semiconductor element 1 is 25° C.

[0139] The following shows a time change ΔVce of the first voltage when correction is not performed using the temperature Tk of the power semiconductor element 1 .

[0140] ΔVce=Vce(n,75℃)-Vce(n-1,125℃)…(3)

[0141] On the other hand, the deteriorated location identification unit 9 of the present embodiment obtains the time change ΔVce(25° C.) of the first voltage using Vce(n, 25° C.) and Vce(n−1, 25° C.).

[0142] ΔVce(25℃)=Vce(n,25℃)-Vce(n-1,25℃)…(4)

[0143] Fig.16 : is a graph which shows the relationship between the collector current Ic and the second voltage Vee in the IGBT.

[0144] The second voltage Vee changes according to the collector current Ic and the temperature Tk of the power semiconductor element 1 .

[0145] Even when the power semiconductor element 1 is energized with the same collector current Ic, the resistance value of the metal layer on the surface of the emitter electrode surface 12 of the power semiconductor element 1 changes according to the temperature Tk. As a result, for example, the value of the second voltage Vee generated at 25°C is different from the value of the second voltage Vee generated at 125°C.

[0146] In the present embodiment, the deteriorated location identification unit 9 corrects the time variation ΔVee of the second voltage Vee based on the temperature Tk of the power semiconductor element 1 .

[0147] Fig.17 It is a diagram for explaining correction of the second voltage Vee at the (n-1) time point.

[0148] When the temperature Tk of the power semiconductor element 1 is 125°C and the second voltage Vee is Vee(n-1,125°C) at the time point (n-1), the degradation location identification unit 9 determines that Fig.17 As shown, under the condition that the collector current Ic is the same, the second voltage Vee (n-1, 25° C.) is obtained when the temperature Tk of the power semiconductor element 1 is 25° C.

[0149] Fig.18 : is a diagram for explaining correction of the second voltage Vee at time point n.

[0150] When the temperature Tk of the power semiconductor element 1 is 75° C. and the second voltage Vee is Vee(n, 75° C.) at time point n, the degradation location identification unit 9 determines that Fig.18As shown, the second voltage Vee (n, 25° C.) is obtained when the temperature Tk of the power semiconductor element 1 is 25° C. under the condition that the collector current Ic is the same.

[0151] The following shows a time change ΔVee of the second voltage when correction is not performed using the temperature Tk of the power semiconductor element 1 .

[0152] ΔVee=Vee(n,75℃)-Vee(n-1,125℃)…(5)

[0153] On the other hand, the deteriorated location identification unit 9 of the present embodiment obtains the time change ΔVee(25° C.) of the second voltage using Vee(n, 25° C.) and Vee(n−1, 25° C.).

[0154] ΔVee(25℃)=Vee(n,25℃)-Vee(n-1,25℃)…(6)

[0155] The deteriorated location identifying unit 9 uses Fig. 9 The lookup table is used to determine the deteriorated location corresponding to the combination of the corrected first voltage change ΔVce(25°C) of equation (4) and the corrected second voltage change ΔVee(25°C) of equation (6).

[0156] As described above, according to this embodiment, even when the temperature Tk of the power semiconductor element 1 is different from the standard temperature regarded as a premise by the lookup table, the change ΔVce of the first voltage and the change ΔVee of the second voltage can be corrected according to the temperature Tk of the power semiconductor element 1, thereby determining the deteriorated location using the lookup table of the standard temperature.

[0157] Implementation method 5.

[0158] In the fifth embodiment, the first voltage change ΔVce and the second voltage change ΔVee are corrected using the temperature Tk of the power semiconductor element 1 as in the fourth embodiment, but the temperature Tk of the power semiconductor element 1 is estimated without using the temperature sensor 27 .

[0159] Fig.19 1 is a diagram showing the relationship between the collector current Ic and the second voltage Vee at three temperatures Tk of the power semiconductor element 1 .

[0160] like Fig.19 As shown, unless the first bonding wire 15 is degraded, when the collector current Ic is constant, the second voltage Vee changes according to the temperature Tk of the power semiconductor element 1. This is because the elements of the second voltage Vee are composed only of metals such as the emitter electrode surface 12 and the bonding wire 15.

[0161] When the collector current Ic is constant, the second voltage Vee changes at a predetermined ratio in accordance with changes in the temperature Tk of the power semiconductor element 1 .

[0162] For example, when the collector current Ic is Ic0, the second voltage when the temperature of the power semiconductor element 1 is 25°C is Vee(25°C). When the collector current Ic is Ic0, the second voltage Vee(75°C) when the temperature of the power semiconductor element 1 is 75°C is 1.2×Vee(25°C), and the second voltage Vee(125°C) when the temperature of the power semiconductor element 1 is 125°C is 1.4×Vee(25°C).

[0163] When the collector current Ic is the same, and the second voltage Vee when the temperature of the power semiconductor element 1 is the standard temperature T0 is defined as the standard voltage Vee0, the second voltage Vee measured when the temperature of the power semiconductor element 1 is Tk has the following relationship.

[0164] Vee=K1(Tk-T0)+Vee0 …(7)

[0165] The resistance Ree (= Vee / Ic) (hereinafter referred to as the second resistance) of the current path between the emitter reference terminal 4 and the emitter main terminal 3, which is represented by the division value of the second voltage Vee and the collector current Ic, is independent of the collector current Ic, and changes at a predetermined ratio according to changes in the temperature Tk of the power semiconductor element 1.

[0166] For example, the second resistance when the temperature of the power semiconductor element 1 is 25°C is set to Ree(25°C). The second resistance Ree(75°C) when the temperature of the power semiconductor element 1 is 75°C is 1.2×Ree(25°C), and the second voltage Vee(125°C) when the temperature of the power semiconductor element 1 is 125°C is 1.4×Ree(25°C).

[0167] Assuming that the second resistance Ree when the temperature of the power semiconductor element 1 is a standard temperature T0 is referred to as a standard resistance Ree0, the second resistance Ree measured when the temperature of the power semiconductor element 1 is Tk has the following relationship.

[0168] Ree=K2(Tk-T0)+Ree0 …(8)

[0169] When the bonding portion 20 of the first bonding wire 15 is degraded, the above premise does not hold.

[0170] Generally speaking, the effect of the degradation of the joint 20 of the first bonding wire 15 on the second voltage Vee occurs instantaneously. The degradation of the joint 20 of the first bonding wire 15 occurs due to the lift-off of the joint portion. Even if the partial lift-off of the joint 20 gradually progresses and the joint area gradually decreases, the second voltage Vee hardly changes until the joint 20 is completely lifted off. This is because the resistance value of the joint 20 is originally very small because the joint 20 is very thin.

[0171] When explaining with a simple example, it is assumed that the cross-sectional area of ​​the joint 20 is the same as the cross-sectional area of ​​the first bonding wire 15, and the thickness of the joint 20 (the thickness of the crack that penetrates from the surrounding) is 1nm, and the crack penetrates from the surrounding of the joint 20 and the cross-sectional area of ​​the joint 20 becomes 1 / 1000. The increase in resistance is equal to the increase in resistance when the length of the first bonding wire 15 is extended by 1000 times of 1nm, that is, 1μm. The increase in resistance when the area of ​​the joint 20 is reduced to 1 / 100000 is equal to the increase in resistance when the length of the first bonding wire 15 is extended by 1mm. At the moment when the peeling of the joint 20 is fully developed and the first bonding wire 15 is completely separated from the emitter electrode surface 12, the resistance of the joint 20 instantly becomes infinite, and the second voltage Vee changes greatly. In other words, the change in the second voltage Vee is instantaneous. Therefore, by always recording the change in the second voltage Vee, the standard voltage Vee0 or the standard resistance Ree0 can be corrected assuming that the temperature immediately before and after the instantaneous increase in the second voltage Vee are the same.

[0172] Fig. 20 1 is a diagram showing a configuration of a semiconductor device according to Embodiment 5. The semiconductor device according to Embodiment 5 includes a voltage history recording unit 31 and a temperature estimating unit 32 in addition to the components of the semiconductor device according to Embodiment 1.

[0173] The voltage history recording unit 31 stores the history of the second voltage Vee.

[0174] When the collector current Ic flowing through the power semiconductor element 1 is constant, the temperature estimation unit 32 estimates the temperature Tk of the power semiconductor element based on the second voltage Vee, the standard temperature T0, and the second voltage Vee at the standard temperature T0, that is, the standard voltage Vee0. When the time change rate dVee of the second voltage is greater than the reference value TH1, the temperature estimation unit 32 updates the standard voltage Vee0 based on the time change rate dVee of the second voltage.

[0175] Fig.21 This is a flowchart showing the process of estimating the temperature of the power semiconductor element 1 and identifying the deteriorated portion according to the fifth embodiment.

[0176] In step S101, the temperature estimation unit 32 sets the standard voltage Vee0, which is the second voltage Vee for the standard temperature T0 of the power semiconductor element 1, as the initial value V0. The temperature estimation unit 32 sets the collector current Ic to a constant value Ic0.

[0177] In step S102 , the temperature estimation unit 32 obtains the first voltage Vce measured by the first voltage measurement circuit 5 and the second voltage Vee measured by the second voltage measurement circuit 6 .

[0178] In step S103, the temperature estimation unit 32 calculates the time change rate dVee of the second voltage. That is, when the latest second voltage is set as Vee(n) and the second voltage recorded in the voltage history recording unit 31 one time point before is set as Vee(n-1), the temperature estimation unit 32 calculates the time change rate dVee of the second voltage Vee according to the following formula.

[0179] dVee={Vee(n)-Vee(n-1)} / Vee(n-1)…(9)

[0180] In step S104 , when the time change rate dVee of the second voltage is equal to or greater than the reference value TH1 , the process proceeds to step S105 , and when the time change rate dVee of the second voltage is less than the reference value TH1 , the process proceeds to step S106 .

[0181] In step S105, the temperature estimation unit 32 updates the standard voltage Vee0. That is, the temperature estimation unit 32 sets a value obtained by multiplying the current standard voltage Vee0 by (1+dVee) as a new standard voltage Vee0.

[0182] In step S106 , the temperature estimation unit 32 estimates the temperature Tk of the power semiconductor element 1 based on the standard temperature T0 , the standard voltage Vee0 , and the second voltage Vee as shown in the following equation.

[0183] Tk=(Vee-Vee0) / K1+T0 …(10)

[0184] In step S107 , the deteriorated location identification unit 9 corrects the change ΔVce of the first voltage and the change ΔVee of the second voltage based on the temperature Tk of the power semiconductor element 1 , similarly to the fourth embodiment.

[0185] In step S108 , the deteriorated location identification unit 9 refers to the lookup table using the corrected first voltage change ΔVce and the corrected second voltage change ΔVee to identify the deteriorated location.

[0186] Fig. 22: is a graph showing the time change of the standard voltage Vee0.

[0187] When there is no degradation in any of the bonding parts of the plurality of first bonding wires 15, the standard voltage Vee0 is set to the initial value V0. When the first of the bonding parts of the plurality of bonding wires 15 is degraded, step S105 is performed for the first time, and the standard voltage Vee0 is set to V1. When the second of the bonding parts of the plurality of first bonding wires 15 is degraded, step S105 is performed for the second time, and the standard voltage Vee0 is set to V2. When the third of the plurality of bonding wires 15 is degraded, step S105 is performed for the third time, and the standard voltage Vee0 is set to V3.

[0188] In this way, by updating the standard voltage Vee0 according to the degradation of the first bonding wire 15 , it is possible to always accurately correct the influence of temperature.

[0189] In order to prevent the instantaneous increase of the second voltage Vee from being missed, the second voltage Vee is sampled at short time intervals. The voltage history recording unit 31 may store the second voltage Vee at one time point before.

[0190] As described above, according to the semiconductor device of the fifth embodiment, the temperature Tk of the power semiconductor element 1 can be estimated from the measured value of the second voltage Vee without providing a temperature sensor.

[0191] Implementation method 6.

[0192] Fig.23 This is a diagram showing the structure of a semiconductor device according to a sixth embodiment.

[0193] The semiconductor device of the sixth embodiment includes a resistance history recording unit 131 and a temperature estimating unit 132 in addition to the components of the semiconductor device of the first embodiment.

[0194] The resistance history recording unit 131 stores the history of the second resistor Ree.

[0195] The temperature estimation unit 132 estimates the temperature Tk of the power semiconductor element based on the second resistor Ree, the standard temperature T0, and the second resistor Ree at the standard temperature T0, that is, the standard resistor Ree0. When the time change rate dRee of the second resistor is greater than the reference value TH2, the temperature estimation unit 132 updates the standard resistor Ree0 based on the time change rate dRee of the second resistor.

[0196] Fig.24 This is a flowchart showing the process of estimating the temperature of the power semiconductor element 1 and identifying the deteriorated portion according to the sixth embodiment.

[0197] In step S201 , the temperature estimation unit 132 sets the resistance Ree for the standard temperature T0 of the power semiconductor element 1 , that is, the standard resistance Ree0 , to an initial value R0 .

[0198] In step S202 , the temperature estimation unit 132 obtains the first voltage Vce measured by the first voltage measurement circuit 5 and the second voltage Vee measured by the second voltage measurement circuit 6 .

[0199] In step S203 , the temperature estimation unit 132 calculates the second resistance Ree (Vee / Ic) by dividing the second voltage Vee by the collector current Ic.

[0200] In step S204, the temperature estimation unit 132 calculates the time change rate dRee of the second resistor Ree. That is, when the latest second resistor is Ree(n) and the second resistor one time point ago is Ree(n-1), the temperature estimation unit 132 calculates the time change rate dRee of the second resistor Ree according to the following formula.

[0201] dRee={Ree(n)-Ree(n-1)} / Ree(n-1)…(11)

[0202] In step S205 , when the time change rate dRee of the second resistor Ree is greater than or equal to the reference value TH2 , the process proceeds to step S206 , and when the time change rate dRee of the second resistor Ree is less than the reference value TH2 , the process proceeds to step S207 .

[0203] In step S206, the temperature estimation unit 132 updates the standard resistance Ree0. That is, the temperature estimation unit 132 sets a value obtained by multiplying the current standard resistance Ree0 by (1+dRee) as the new standard resistance Ree0.

[0204] In step S207 , the temperature estimation unit 132 estimates the temperature Tk of the power semiconductor element 1 based on the reference temperature T0 , the reference resistance Ree0 , and the second resistance Ree.

[0205] Tk=(Ree-Ree0) / K2+T0 …(12)

[0206] In step S208 , the deteriorated location identification unit 9 corrects the change ΔVce of the first voltage and the change ΔVee of the second voltage based on the temperature Tk of the power semiconductor element 1 , similarly to the fourth embodiment.

[0207] In step S209 , the deteriorated location identification unit 9 identifies the deteriorated location by referring to the lookup table using the corrected first voltage change ΔVce and the corrected second voltage change ΔVee.

[0208] As described above, according to the semiconductor device of the sixth embodiment, the temperature Tk of the power semiconductor element 1 can be estimated based on the second resistance Ree obtained from the measured value of the second voltage Vee and the collector current Ic without providing a temperature sensor. In the semiconductor device of the fifth embodiment, in order to estimate the temperature Tk of the power semiconductor element 1, the collector current Ic needs to be constant. In contrast, in the semiconductor device of the sixth embodiment, the temperature Tk of the power semiconductor element 1 can be estimated even if the collector current Ic is not constant.

[0209] Implementation method 7.

[0210] In this embodiment, the semiconductor devices of the above-mentioned Embodiments 1 to 6 are applied to a power conversion device. This embodiment is not limited to a specific power conversion device, and the following describes a case where Embodiments 1 to 6 are applied to a three-phase inverter.

[0211] Fig.25 This is a block diagram showing the configuration of a power conversion system according to a seventh embodiment.

[0212] The power conversion system includes a power source 100 , a power conversion device 200 , and a load 300 .

[0213] The power supply 100 is a DC power supply, and supplies DC power to the power conversion device 200. The power supply 100 can be composed of various power supplies. For example, the power supply 100 can be composed of a DC system, a solar cell, or a storage battery. The power supply 100 can also be composed of a rectifier circuit or an AC / DC converter connected to an AC system. The power supply 100 can also be composed of a DC / DC converter that converts the DC power output from the DC system into a predetermined power.

[0214] The power conversion device 200 is a three-phase inverter connected between the power supply 100 and the load 300. The power conversion device 200 converts the DC power supplied from the power supply 100 into AC power, and supplies the AC power to the load 300. The power conversion device 200 includes: a main conversion circuit 201 that converts the DC power into AC power and outputs it; and a control circuit 203 that outputs a control signal for controlling the main conversion circuit 201 to the main conversion circuit 201.

[0215] The load 300 is a three-phase motor driven by the AC power supplied from the power conversion device 200. The load 300 is not limited to a specific use, and is a motor mounted on various electrical devices. For example, the load 300 is a motor mounted on a hybrid vehicle, an electric vehicle, a railway vehicle, an elevator, or an air conditioner.

[0216] The power conversion device 200 will be described in detail below.

[0217] The main conversion circuit 201 includes a semiconductor module 202. The semiconductor module 202 includes a switching element and a freewheeling diode (not shown). The switching element switches to convert the DC power supplied from the power supply 100 into AC power and supplies it to the load 300. The degradation monitoring unit 205 of the first to sixth embodiments may also be configured as follows. Fig.25 As shown, the degradation monitoring unit 205 is disposed inside the semiconductor module 202. Alternatively, the degradation monitoring unit 205 may be disposed outside the semiconductor module 202.

[0218] The specific circuit structure of the main conversion circuit 201 has various structures. The main conversion circuit 201 of this embodiment is a 2-level three-phase full-bridge circuit. This circuit can be composed of 6 switching elements and 6 freewheeling diodes connected in anti-parallel with each switching element. Each switching element of the main conversion circuit 201 is equivalent to the power semiconductor element 1 of the above-mentioned embodiments 1 to 6. The semiconductor module 202 is equivalent to the power module of the above-mentioned embodiments 1 to 6. The 6 switching elements are connected in series with every two switching elements to form upper and lower branches. Each upper and lower branch constitutes each phase (U phase, V phase, W phase) of the full-bridge circuit. The output terminals of each upper and lower branch, that is, the three output terminals of the main conversion circuit 201, are connected to the load 300.

[0219] The main conversion circuit 201 is provided with a driving circuit (not shown) for driving each switching element. The driving circuit may be built into the semiconductor module 202, or may be a structure that has a driving circuit separately from the semiconductor module 202. The driving circuit generates a driving signal for driving the switching element of the main conversion circuit 201, and supplies it to the control electrode of the switching element of the main conversion circuit 201. Specifically, the driving circuit outputs a driving signal for setting the switching element to the on state and a driving signal for setting the switching element to the off state to the control electrode of each switching element according to the control signal from the control circuit 203. When the switching element is maintained in the on state, the driving signal is a voltage signal (on signal) above the threshold voltage of the switching element, and when the switching element is maintained in the off state, the driving signal is a voltage signal (off signal) below the threshold voltage of the switching element.

[0220] The control circuit 203 controls the switch elements of the main conversion circuit 201 in such a manner that the desired power is supplied to the load 300. Specifically, the time (on-time) when each switch element of the main conversion circuit 201 should be in the on state is calculated according to the power to be supplied to the load 300. For example, the control circuit 203 can control the main conversion circuit 201 by PWM (Pulse Width Modulation) control that modulates the on time of the switch element according to the voltage to be output. The control circuit 203 outputs a control instruction (control signal) to the drive circuit included in the main conversion circuit 201 in such a manner that the switch element that becomes the on state is output at each time point, and the switch element that becomes the off state is output. The drive circuit outputs an on signal or an off signal as a drive signal to the control electrode of each switch element in accordance with the control signal.

[0221] The power module of the power conversion device according to the present embodiment includes the degradation monitoring unit 205 of Embodiments 1 to 6. Thus, it is possible to detect which of the bonding portions between the plurality of first bonding wires 15 and the power semiconductor element 1 has degraded, and estimate the life of the power semiconductor element 1 and the semiconductor module 202. The degradation monitoring unit 205 outputs information on degradation or life to the control circuit 203, and corrects the drive signal output from the drive device as needed.

[0222] In this embodiment, an example of applying embodiments 1 to 6 to a 2-level three-phase inverter is described, but embodiments 1 to 6 can be applied to various power conversion devices. Although a 2-level power conversion device is used in this embodiment, a 3-level or multi-level power conversion device may be used. In the case of supplying power to a single-phase load, embodiments 1 to 6 may also be applied to a single-phase inverter. In addition, in the case of supplying power to a DC load, embodiments 1 to 6 may also be applied to a DC / DC converter or an AC / DC converter.

[0223] In addition, the load 300 connected to the power conversion device 200 is not limited to the motor. The power conversion device 200 can also be used as a power supply device for an electric discharge machine, a laser processing machine, an induction heating cooker, or a contactless power supply system. The power conversion device 200 can also be used as a power conditioner for a solar power generation system or a power storage system.

[0224] Fig.26 This is a diagram showing a specific configuration of the degradation monitoring unit 205 according to the first to sixth embodiments.

[0225] For example, Figure 1 The functions of the deterioration location identification unit 9 and the lookup table storage unit 19 are implemented by the processing circuit 1001 .

[0226] The processing circuit 1001 can be implemented by dedicated hardware. The processing circuit may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof.

[0227] Fig. 27 1 is a diagram showing an example in which the processing circuit 1001 is realized by software.

[0228] like Fig. 27 As shown, the processing circuit 1001 can also realize the functions of each part by the processor 1002 reading out and executing the program stored in the memory 1003. The processor 1002 corresponds to a CPU (Central Processing Unit), a processing device, an arithmetic device, a microprocessor, a microcomputer or a DSP (Digital Signal Processor).

[0229] The functions of the deterioration location determination unit 9 and the query table storage unit 19 are implemented by software, firmware, or a combination of software and firmware. The software or firmware is described as a program and stored in the memory 1003. The memory 1003 may be, for example, a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable Read Only Memory), an EEPROM (Electrically Erasable Programmable Read Only Memory), or a non-volatile or volatile semiconductor memory such as a magnetic disk, a floppy disk, an optical disk, a high-density disk, a mini disk, or a DVD (Digital Versatile Disc).

[0230] Furthermore, each function of the deteriorated location identifying unit 9 and the lookup table storage unit 19 may be partially implemented by dedicated hardware and partially implemented by software or firmware.

[0231] In this way, the processing circuit 1001 can implement the above functions through hardware, software, firmware or a combination thereof.

[0232] (Variation Example)

[0233] (1) In the above-mentioned embodiment, an example of using an IGBT as the power semiconductor element 1 is cited, but the type of power semiconductor element is not limited to the IGBT, and for example, a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) may also be used. In this case, by replacing the "collector" with the "drain" and the "emitter" with the "source", the same application can be achieved. Similarly, "Vce" can be replaced with "Vds" and "Vee" can be replaced with "Vss".

[0234] (2) Fig.28 2 is a diagram showing another example of the correspondence relationship between the first degraded location and the combination of the time change ΔVce of the first voltage Vce and the time change ΔVce of the second voltage Vee.

[0235] When the first degraded portion is the joint portion 20A, the first voltage Vce increases by more than 20%, and the second voltage Vee increases by more than 10%. When the first degraded portion is the joint portion 20B, the first voltage Vce increases by more than 20%, and the second voltage Vee increases by more than 40%. When the first degraded portion is the joint portion 20C, the first voltage Vce increases by more than 30%, and the second voltage Vee increases by more than 10%. When the first degraded portion is the joint portion 20D, the first voltage Vce increases by more than 30%, and the second voltage Vee increases by more than 40%.

[0236] Fig.29 FIG. 1 is a diagram showing another example of a lookup table for determining the first deteriorated part. Fig.28 The query table is derived based on the corresponding relationship.

[0237] It is stipulated that when the first voltage Vce increases by more than 20% and less than 30% and the second voltage Vee increases by more than 10% and less than 40%, the first degraded portion is the junction portion 20A. It is stipulated that when the first voltage Vce increases by more than 30% and the second voltage Vee increases by more than 10% and less than 40%, the first degraded portion is the junction portions 20A and 20C. It is stipulated that when the first voltage Vce increases by more than 20% and less than 30% and the second voltage Vee increases by more than 40%, the first degraded portion is the junction portions 20A and 20B. It is stipulated that when the first voltage Vce increases by more than 30% and the second voltage Vee increases by more than 40%, the first degraded portion is the junction portions 20A, 20B, 20C and 20D.

[0238] The deterioration location identification unit 9 refers to Fig.29The degradation location identifying unit 9 determines the degradation location corresponding to the combination of the time change ΔVce of the first voltage Vce and the time change ΔVce of the second voltage Vee by using the query table. If the combination of the time change ΔVce of the first voltage Vce and the time change ΔVce of the second voltage Vee is not included in the query table, the degradation location identifying unit 9 determines that there is no degradation location in the plurality of junctions between the plurality of first bonding wires 15 and the emitter electrode surfaces 12 connected thereto.

[0239] The embodiments disclosed herein are to be understood in all respects as illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the claims.

Claims

1. A semiconductor device comprising: Power semiconductor components; A collector substrate electrically connected to the power semiconductor element; A collector main terminal, electrically connected to the collector substrate; An emitter main terminal connected to the emitter electrode surface of the power semiconductor element through a plurality of first bonding wires; an emitter reference terminal connected to the emitter electrode surface of the power semiconductor element through a second bonding wire; a first voltage measuring circuit for measuring a first voltage which is a difference between a potential of the collector main terminal and a potential of the emitter main terminal; a second voltage measuring circuit for measuring a second voltage which is a difference between a potential of the emitter reference terminal and a potential of the emitter main terminal; as well as The degradation location determination unit determines the degradation location corresponding to the combination of the time change of the first voltage measured by the first voltage measurement circuit and the time change of the second voltage measured by the second voltage measurement circuit, with reference to the correspondence information of the degradation location among the plurality of junction locations between the plurality of first bonding wires and the respectively connected emitter electrode surfaces, which specifies the combination of the time change of the first voltage and the time change of the second voltage.

2. The semiconductor device according to claim 1, wherein The semiconductor device includes a recording unit that records a history of the identified deteriorated portion.

3. The semiconductor device according to claim 2, wherein: When any of the plurality of joints is not degraded, the degraded portion identifying unit identifies the degraded portion by referring to first correspondence information when there is no degradation as the correspondence information, When any of the plurality of joints is degraded, the degraded portion identifying unit identifies the degraded portion by referring to second correspondence information corresponding to the degraded portion as the correspondence information.

4. The semiconductor device according to claim 2 or 3, wherein: The semiconductor device includes a life estimation unit that estimates the life of the semiconductor device based on the history of the deteriorated portion and a driving method of the power semiconductor element.

5. The semiconductor device according to claim 4, wherein: The lifetime estimation unit switches a driving method of the power semiconductor element according to the estimated lifetime.

6. The semiconductor device according to claim 4, wherein: The lifetime estimation unit notifies a user of a recommendation for switching a driving method of the power semiconductor element based on the estimated lifetime.

7. The semiconductor device according to any one of claims 1 to 6, wherein: The semiconductor device includes a temperature sensor that measures a temperature of the power semiconductor element.

8. The semiconductor device according to any one of claims 1 to 6, wherein: The semiconductor device includes a temperature estimation unit that estimates the temperature of the power semiconductor element based on the second voltage, a standard temperature, and the second voltage at the standard temperature, that is, the standard voltage, when a collector current flowing through the power semiconductor element is constant.

9. The semiconductor device according to claim 8, wherein: When the temporal change ratio of the second voltage is equal to or greater than a reference value, the temperature estimation unit updates the standard voltage according to the temporal change ratio of the second voltage.

10. The semiconductor device according to claim 9, wherein: When the ratio of the time change of the second voltage is ΔVee, the temperature estimation unit sets a value obtained by multiplying the current standard voltage by (1+ΔVee) as a new standard voltage.

11. The semiconductor device according to any one of claims 1 to 6, wherein: The semiconductor device includes a temperature estimation unit that estimates the temperature of the power semiconductor element based on a second resistance obtained by dividing the second voltage by a collector current flowing through the power semiconductor element, a standard temperature, and a standard resistance which is the second resistance at the standard temperature.

12. The semiconductor device according to claim 11, wherein When the ratio of the time change of the second resistor is equal to or greater than a reference value, the temperature estimation unit updates the reference resistor according to the ratio of the time change of the second resistor.

13. The semiconductor device according to claim 12, wherein: When the ratio of the time change of the second resistance is ΔRee, the temperature estimation unit sets a value obtained by multiplying the current standard resistance by (1+ΔRee) as a new standard resistance.

14. The semiconductor device according to any one of claims 7 to 13, wherein: The correspondence information specifies a deteriorated portion among the plurality of junction portions for a combination of a time change of the first voltage and a time change of the second voltage at a standard temperature. The degradation location determination unit corrects the measured time variation of the first voltage and the time variation of the second voltage according to the temperature of the power semiconductor element, and determines the degradation location corresponding to the combination of the corrected time variation of the first voltage and the corrected time variation of the second voltage with reference to the corresponding information.

15. A power conversion device comprising: The semiconductor device according to any one of claims 1 to 14; A main conversion circuit converts input power and outputs it; and The control circuit outputs a control signal for controlling the main conversion circuit to the main conversion circuit.

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