Deterioration diagnosing device and semiconductor device provided with the same

Abstract

A deterioration diagnosis device (100) includes a voltage measurement unit (101) that measures a voltage between a first main terminal (3) and a second main terminal (5) of a semiconductor module (1) or a voltage between a reference terminal (6) and the second main terminal (5) of the semiconductor module (1), and a diagnosis processing unit (102) that diagnoses deterioration of the semiconductor module (1) based on a measurement result in the voltage measurement unit (101) that measures a first voltage at a first time immediately after a main current starts to flow to the semiconductor module (1) and a second voltage at a second time after the first time, and diagnoses deterioration of a joining material (11) that joins a first main electrode (3a) of a semiconductor element (2) included in the semiconductor module (1) based on a comparison between the first voltage and the second voltage.

Description

Technical Field

[0001] This disclosure relates to a degradation diagnosis apparatus for diagnosing degradation of semiconductor modules and a semiconductor device having the same. Background Technology

[0002] As a technique for detecting the degradation of semiconductor modules, a degradation detection device having a monitoring unit is known, which monitors an input value that changes based on the detected value of the voltage in the conduction state between the collector terminal and the emitter terminal, and has a low-pass filter that performs low-pass filtering on the input value (Patent Document 1).

[0003] Existing technical documents

[0004] Patent Document 1: Japanese Patent Application Publication No. 2023-109223 Summary of the Invention

[0005] Representative forms of semiconductor module degradation include degradation of bonding materials and degradation of wiring junctions. Degradation of bonding materials refers to the formation of cracks in the bonding material between the first main electrode of the semiconductor element and the conductive component electrically connected to the first main electrode. Degradation of wiring junctions refers to the formation of cracks in the junction between the wiring bonded to the second main electrode of the semiconductor element and the second main electrode.

[0006] According to existing technology (e.g., Patent Document 1), it is possible to detect at least one of the joints of the bonding materials or wiring, or both of them, deterioration. However, it is not possible to diagnose the deterioration of the bonding materials alone.

[0007] The invention disclosed herein was made in view of the following circumstances, and is intended to provide a degradation diagnostic device capable of independently diagnosing degradation of bonding materials of a semiconductor module, and a semiconductor device having the same.

[0008] One aspect of this disclosure relates to a degradation diagnostic apparatus for diagnosing degradation of a semiconductor module having a semiconductor element having a first main electrode and a second main electrode. The degradation diagnostic apparatus comprises: a voltage measuring unit for measuring the voltage between a first main terminal electrically connected to the first main electrode and a second main terminal electrically connected to the second main electrode, or the voltage between a reference terminal and a second main terminal for detecting the potential of the second main electrode; and a diagnostic processing unit for diagnosing degradation of the semiconductor module based on the measurement results in the voltage measuring unit. The voltage measuring unit measures a first voltage at a first moment during a period when the main current begins to flow into the semiconductor module and the voltage between the first main terminal and the second main terminal, or the voltage between the reference terminal and the second main terminal, transitionally increases, and a second voltage at a second moment after the first moment. The diagnostic processing unit diagnoses degradation of a bonding material bonded to the first main electrode based on a comparison of the first and second voltages.

[0009] Another aspect of this disclosure relates to a degradation diagnostic apparatus for diagnosing degradation of a semiconductor module having a semiconductor element having a first main electrode and a second main electrode. The degradation diagnostic apparatus is characterized by comprising: a voltage measuring unit for measuring the voltage between a first main terminal electrically connected to the first main electrode and a second main terminal electrically connected to the second main electrode, or the voltage between a reference terminal and the second main terminal for detecting the potential of the second main electrode; and a diagnostic processing unit for diagnosing degradation of the semiconductor module based on the measurement results in the voltage measuring unit. The voltage measuring unit measures the voltage after a first moment following the initial flow of main current into the semiconductor module. The diagnostic processing unit diagnoses degradation of the bonding material bonded to the first main electrode based on a comparison of the first moment and the second moment, wherein the second moment is the moment when a voltage exceeding a predetermined reference value is measured in the voltage measuring unit, resulting from a comparison with the first voltage measured at the first moment.

[0010] According to one aspect of the present disclosure, the degradation diagnostic apparatus is capable of diagnosing the degradation of the bonding material of a semiconductor module independently. Attached Figure Description

[0011] Figure 1 This is a diagram showing a schematic structure of a semiconductor device equipped with the degradation diagnostic device of Embodiment 1.

[0012] Figure 2 This is a diagram showing the schematic structure of the diagnostic processing unit included in the degradation diagnostic device of Embodiment 1.

[0013] Figure 3 This is a diagram showing the cross-sectional structure of a semiconductor module that is the target of a diagnostic device as described in Embodiment 1.

[0014] Figure 4 yes Figure 3 An enlarged view of part A shown.

[0015] Figure 5 This is a graph showing an example of the waveform of Vee in a non-degraded state of the semiconductor module.

[0016] Figure 6 This is a graph illustrating an example of the waveform of a Vee in a semiconductor module with only joint degradation.

[0017] Figure 7 This is a graph illustrating an example of the waveform of a Vee that only bonds to a semiconductor module with deteriorated materials.

[0018] Figure 8 This is a graph illustrating an example of the waveform of the Vee in a semiconductor module, showing the bonding material and the deterioration of the bonding joint.

[0019] Figure 9 This is a graph showing an example of the waveform of the Vee in a semiconductor module that has undergone some degree of degradation.

[0020] Figure 10 This is a diagram showing a schematic structure of a semiconductor device having a modified embodiment of the degradation diagnostic apparatus of embodiment 1.

[0021] Figure 11 This is a diagram showing other structural examples of a semiconductor device having a modified embodiment of the degradation diagnostic apparatus of embodiment 1.

[0022] Figure 12 This is a diagram showing a schematic structure of a semiconductor device equipped with the degradation diagnostic device of Embodiment 2.

[0023] Figure 13 This is a diagram showing the schematic structure of the diagnostic processing unit included in the degradation diagnostic device of Embodiment 2.

[0024] Figure 14 This is a graph illustrating the method for diagnosing the degradation of the semiconductor module in Embodiment 2.

[0025] Figure 15 This is a diagram showing a schematic structure of a semiconductor device equipped with the degradation diagnostic device of embodiment 3.

[0026] Figure 16 This is a diagram showing the schematic structure of the diagnostic processing unit included in the degradation diagnostic device of Embodiment 3.

[0027] Figure 17 This is a graph illustrating the method for diagnosing the degradation of the semiconductor module in Embodiment 3.

[0028] Figure 18 This is a diagram showing an example of the hardware structure of the diagnostic processing unit. Detailed Implementation

[0029] Hereinafter, based on the accompanying drawings, a degradation diagnosis apparatus according to an embodiment of the present disclosure will be described. Furthermore, the following drawings are schematic illustrations, and the aspect ratios and number of constituent elements shown in the drawings may not necessarily correspond to the actual aspect ratios and number of constituent elements.

[0030] Furthermore, in the description of embodiments of this disclosure, repeated descriptions of substantially the same structures are sometimes omitted. Additionally, detailed descriptions of matters already well known are sometimes omitted. This is done to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art.

[0031] Implementation method 1.

[0032] Reference Figures 1 to 9 Implementation method 1 is described below.

[0033] [1-1. Structure]

[0034] Figure 1 This is a diagram showing a schematic structure of a semiconductor device 200 equipped with the degradation diagnostic device 100 of Embodiment 1. (See diagram for details.) Figure 1 As shown, the semiconductor device 200 includes a semiconductor module 1 and a degradation diagnostic device 100.

[0035] like Figure 1 As shown, the semiconductor module 1 includes a semiconductor element 2, a collector main terminal 3 serving as a first main terminal, a gate terminal 4 serving as a control terminal, an emitter main terminal 5 serving as a second main terminal, and an emitter reference terminal 6 serving as a reference terminal. Figure 1 As shown, collector main terminal 3, gate terminal 4, emitter main terminal 5, and emitter reference terminal 6 are connected to semiconductor element 2. Furthermore, the resistance shown between semiconductor element 2 and collector main terminal 3 represents the collector-side parasitic resistance component 13. Additionally, the resistance shown between semiconductor element 2 and emitter main terminal 5 represents the emitter-side parasitic resistance component 14.

[0036] Furthermore, an example of an IGBT (Insulated-Gate Bipolar Transistor) is shown here for semiconductor element 2. However, the semiconductor element 2 included in semiconductor module 1 is not limited to an IGBT. Semiconductor element 2 may also be a MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor). In the case where semiconductor element 2 is a MOSFET, in the description of embodiments of this disclosure, the collector is referred to as the drain and the emitter as the source. In the following description, the case where semiconductor element 2 is an IGBT will be illustrated.

[0037] Semiconductor element 2 operates in either a conducting state where current flows between collector main terminal 3 and emitter main terminal 5, or a cutting-off state where no current flows between them. The conducting and cutting-off states are switched based on the voltage (gate voltage) applied between gate terminal 4 and emitter reference terminal 6. When semiconductor element 2 is in the conducting state, a main current flows between collector main terminal 3 and emitter main terminal 5. That is, collector main terminal 3 and emitter main terminal 5 are terminals through which the main current flows. On the other hand, no main current flows between gate terminal 4 and emitter reference terminal 6. Emitter reference terminal 6 is a reference terminal for detecting the emitter potential of semiconductor element 2.

[0038] like Figure 1 As shown, the degradation diagnostic device 100 includes a voltage measurement unit 101 and a diagnostic processing unit 102.

[0039] Emitter main terminal 5 and emitter reference terminal 6 are connected to voltage measurement unit 101. Voltage measurement unit 101 measures the voltage Vee, which is the difference between the potential of emitter main terminal 5 and the potential of emitter reference terminal 6, and outputs it to diagnostic processing unit 102.

[0040] The diagnostic processing unit 102 is connected to the voltage measurement unit 101. Based on the measurement results from the voltage measurement unit 101, the diagnostic processing unit 102 diagnoses the degradation of the semiconductor module 1. Furthermore, the connection between the voltage measurement unit 101 and the diagnostic processing unit 102 can be either wired or wireless. When the connection between the voltage measurement unit 101 and the diagnostic processing unit 102 is wireless, both the voltage measurement unit 101 and the diagnostic processing unit 102 possess wireless communication capabilities.

[0041] Figure 2 This is a diagram showing a schematic structure of the diagnostic processing unit 102 included in the degradation diagnostic device 100 of Embodiment 1. Figure 2As shown, the diagnostic processing unit 102 includes a first arithmetic unit 103, a second arithmetic unit 104, a third arithmetic unit 105, a first storage unit 106, and a second storage unit 107. These functions will be explained in the subsequent description of the operation.

[0042] Figure 3 This is a diagram showing the cross-sectional structure of the semiconductor module 1, which is the target of the degradation diagnostic device 100. Additionally, Figure 4 Is Figure 3 The enlarged view of part A is shown using a rectangle with dashed lines.

[0043] like Figure 3 As shown, semiconductor module 1 includes semiconductor element 2, conductive component 10, bonding material 11, collector main terminal 3, emitter main terminal 5, emitter reference terminal 6, collector main current wiring 7, emitter main current wiring 8, and emitter reference wiring 9. Furthermore, semiconductor module 1 as... Figure 1 The diagram shown includes a gate terminal 4. However, in the cross-sectional view... Figure 3 The diagram of gate terminal 4 is omitted.

[0044] like Figure 3 As shown, the semiconductor element 2 has a collector electrode 3a serving as a first main electrode on one side of its main surface, and an emitter electrode 5a serving as a second main electrode on the other side of its main surface.

[0045] like Figure 4 As shown, a joint 12 is formed between the emitter main current wiring 8 (hereinafter referred to as wiring 8) and the emitter electrode 5a. As an example, the joint 12 is formed by solid-state bonding of wiring 8 and emitter electrode 5a by ultrasonic thermoforming.

[0046] Figure 3 The conductive component 10 shown is a layered or plate-shaped component made of a highly conductive material. For example... Figure 3 As shown, a semiconductor element 2 is disposed on the main surface of the conductive component 10. Examples of highly conductive materials constituting the conductive component 10 include aluminum, copper, aluminum-containing alloys, and copper-containing alloys. The conductive component 10 may also be a metal layer obtained by plating the surface of an insulating substrate.

[0047] Figure 3 The bonding material 11 shown is the component that bonds the conductive part 10 and the collector electrode 3a. Examples of bonding materials 11 include solder or conductive adhesive. An example of a conductive adhesive is silver paste.

[0048] Figure 3The collector main current wiring 7 shown is a component that connects the conductive component 10 and the collector main terminal 3. Similarly, the emitter main current wiring 8 is a component that connects the emitter electrode 5a and the emitter main terminal 5. Furthermore, the emitter reference wiring 9 is a component that connects the emitter electrode 5a and the emitter reference terminal 6. As examples of the collector main current wiring 7, emitter main current wiring 8, and emitter reference wiring 9, bonding wires or bonding ribbons can be cited. As examples of materials constituting bonding wires and bonding ribbons, aluminum, copper, gold, or alloys containing at least one of these metals can be cited.

[0049] like Figure 3 As shown, the collector electrode 3a is bonded to the conductive member 10 via the bonding material 11. Furthermore, the conductive member 10 is electrically connected to the collector main terminal 3 via the collector main current wiring 7. That is, it can be said that the collector electrode 3a is electrically connected to the collector main terminal 3 via the bonding material 11. Additionally, the emitter electrode 5a is electrically connected to the emitter main terminal 5 via the emitter main current wiring 8. Furthermore, the emitter electrode 5a is electrically connected to the emitter reference terminal 6 via the emitter reference wiring 9.

[0050] Between the collector main terminal 3 and the collector electrode 3a, there exists a collector-side parasitic resistance component 13 (refer to...). Figure 1 Additionally, between the emitter main terminal 5 and the emitter electrode 5a, there exists an emitter-side parasitic resistance component 14 (see reference). Figure 1 ).

[0051] Here, we will explain the degradation of semiconductor module 1 caused by the repeated operation of semiconductor element 2.

[0052] When the semiconductor element 2 is in the on state, a main current flows through it, causing it to generate heat and its temperature to rise. Furthermore, when the semiconductor element 2 switches from the on state to the off state, it is cooled primarily by heat conduction to the conductive component 10 via the bonding material 11, resulting in a temperature decrease.

[0053] Thus, when the temperature of semiconductor element 2 changes, thermal stress is applied to the connection points of the components connected to semiconductor element 2. Furthermore, during the repeated switching between the on and off states of semiconductor element 2 (hereinafter referred to as on / off operations), cracks sometimes occur at the connection points due to the applied thermal stress. Regarding the cracks occurring at the connection points of semiconductor element 2, their severity gradually increases with the repetition of the on / off operations of semiconductor element 2.

[0054] Among the components connected to the semiconductor element 2 and the connection points of the semiconductor element 2, the bonding material 11 and the joint 12, which are located on the path of the main current and are in contact with the semiconductor element 2 as a heat source, have a higher frequency of crack occurrence and a greater degree of crack propagation compared to other parts. That is, the deterioration of either or both of the bonding material 11 and the joint 12 becomes the main cause of the deterioration of the semiconductor module 1.

[0055] Furthermore, as the semiconductor module 1 deteriorates, its electrical characteristics change. Specifically, when the bonding material 11 deteriorates, the collector-side parasitic resistance component 13 (refer to...) Figure 1 The resistance value of the emitter side increases. Additionally, when the junction 12 deteriorates, the parasitic resistance component 14 on the emitter side (refer to...) Figure 1 The resistance value of ) increases.

[0056] As described above, due to the repeated switching on and off actions of the semiconductor element 2, either or both of the bonding material 11 and the bonding portion 12 deteriorate, thereby causing the semiconductor module 1 to deteriorate. As a result, the electrical characteristics of the semiconductor module 1 change.

[0057] Here, we explain the insights gained through the inventors' dedicated research and the method for diagnosing the degradation of semiconductor module 1 discovered based on these insights. The inventors fabricated various samples of semiconductor module 1 simulating degradation states and conducted experiments using these samples to investigate in detail the relationship between the degradation of semiconductor module 1 and changes in its electrical characteristics. Furthermore, regarding the degradation of semiconductor module 1, the inventors discovered the ability to diagnose, independently, which component, the bonding material 11 or the bonding portion 12, has degraded to what extent.

[0058] First, refer to Figure 5 This indicates that the voltage Vee between the emitter main terminal 5 and the emitter reference terminal 6 was measured when diagnosing the degradation of semiconductor module 1. Figure 5 This is a graph showing an example of the voltage waveform of Vee in the undegraded state (hereinafter referred to as the healthy state) of semiconductor module 1.

[0059] Figure 5 The graph shown illustrates how Vee changes over time t as the main current flows through semiconductor module 1. The horizontal axis of the graph represents time t. Time t0 is the moment when the main current begins to flow into semiconductor module 1. The vertical axis of the graph represents the value of Vee. V0 is the voltage value at which Vee rises sharply immediately after the main current begins flowing into semiconductor module 1 at time t0.

[0060] like Figure 5As shown, the value of Vee gradually increases after reaching V0. This voltage increase is caused by the increase in the resistance of wiring 8. As the main current begins to flow through semiconductor module 1, the temperature of wiring 8 rises, and the resistance of wiring 8 gradually increases. The main reason for the temperature rise of wiring 8 is the heat conduction from semiconductor element 2, which generates heat due to the flow of the main current. The increase in the value of Vee continues until the temperature rise of wiring 8 saturates.

[0061] Figure 5 The V1 shown is the value of Vee after the transient voltage rise associated with the temperature rise of wiring 8 converges. In other words, V1 is the voltage at which the voltage reaches a steady state after the transient rise. Furthermore, time t1 is the moment when Vee reaches V1.

[0062] Based on the above explanation, the waveform of Vee can be examined through the following first to third key points. The first key point is the moment (t0) immediately after the main current begins flowing into semiconductor module 1. The second key point is the period during which the value of Vee rises transitionally (the period from time t0 to time t1). The third key point is the moment (t1) when the transitional voltage rise of Vee converges and Vee reaches V1.

[0063] Next, refer to Figures 6 to 8 This describes the first to third insights obtained by the inventors of the present invention through experiments using a semiconductor module 1 obtained by simulating a deteriorated state.

[0064] The first insight is regarding the relationship between the degradation of the semiconductor module 1 and the waveform of Vee, specifically in the case where only the junction 12 is degraded. The inventors fabricated multiple samples of the semiconductor module 1 with varying degrees of degradation, simulating a state where only the junction 12 is degraded. Furthermore, the waveform of Vee was measured for each of these samples, and comparisons were made. As a result, the inventors obtained the following insight: in the case of only the junction 12 being degraded, the voltage value V0 of Vee immediately after the main current flows into the semiconductor module 1 varies according to the degree of degradation of the junction 12. Additionally, the inventors obtained the following insight: the transient change in the value of Vee progresses approximately the same regardless of the degree of degradation of the junction 12.

[0065] Figure 6 This is a graph illustrating an example of the waveform of the Vee in semiconductor module 1, where only the junction 12 is degraded. Figure 6The graph shows three waveforms superimposed (waveform a1, waveform a2, and waveform a3). Waveform a1, indicated by the dashed line, represents the case where the joint 12 has a minor degree of degradation. Waveform a2, indicated by the single-dotted line, represents the case where the joint 12 has a moderate degree of degradation. Waveform a3, indicated by the solid line, represents the case where the joint 12 has a major degree of degradation.

[0066] like Figure 6 As shown, the value of V0 increases with the degree of degradation of the junction 12. This is because, as the degree of degradation of the junction 12 increases, the resistance value of the emitter-side parasitic resistance component 14 increases.

[0067] like Figure 6 As shown, the curve representing the transitional change in the value of Vee from t0 to t1 exhibits approximately the same shape regardless of the degree of degradation of the junction 12. This can be explained as follows: The increase in the value of Vee from t0 to t1 is caused by the increase in the resistance value of the wiring 8. Furthermore, the resistance value of the wiring 8 increases with the increase in the temperature of the wiring 8. The main reason for the temperature increase of the wiring 8 is the thermal conduction from the semiconductor element 2, which generates heat due to the flow of the main current. Even if the junction 12 deteriorates, the saturation temperature of the semiconductor element 2 hardly changes. In addition, the temperature rise of the semiconductor element 2 from t0 to t1 hardly changes due to the degradation of the junction 12. Therefore, even if the degree of degradation of the junction 12 changes, the shape of the curve representing the transitional change in the value of Vee from t0 to t1 hardly changes. That is, as the degradation of the junction 12 develops, the value of V0 increases, but the curve representing the subsequent transition becomes a similar shape, exhibiting characteristics as if the curve is shifting parallel to the surface.

[0068] The second insight is regarding the relationship between the degradation of the semiconductor module 1 and the waveform of Vee, specifically in the case where only the bonding material 11 is degraded. The inventors fabricated multiple samples of the semiconductor module 1 with varying degrees of degradation, simulating a state where only the bonding material 11 is degraded. Furthermore, the waveform of Vee was measured for each of these samples, and comparisons were made. As a result, the inventors obtained the following insight: in the case of degradation of only the bonding material 11, the transient change in the value of Vee, and the voltage value V1 of Vee after the transient voltage rise converges, vary according to the degree of degradation of the bonding material 11.

[0069] Figure 7 This is a graph illustrating an example of the waveform of Vee in a semiconductor module 1 where only the bonding material 11 has deteriorated. Figure 7The graph shows three waveforms superimposed (waveform b1, waveform b2, and waveform b3). Waveform b1, indicated by the dashed line, represents the case where the bonding material 11 has a minor degree of degradation. Waveform b2, indicated by the dotted line, represents the case where the bonding material 11 has a moderate degree of degradation. Waveform b3, indicated by the solid line, represents the case where the bonding material 11 has a major degree of degradation.

[0070] like Figure 7 As shown, the slope of the curve representing the transitional change in the value of Vee from t0 to t1 increases with the degree of degradation of the bonding material 11. Here, the slope of the curve representing the transitional change in the value of Vee can also be referred to as the change in the value of Vee per unit time. Furthermore, the value of V1 increases with the degree of degradation of the bonding material 11. This can be explained as follows: When the bonding material 11 deteriorates, the thermal resistance in the heat dissipation path from the semiconductor element 2 to the conductive component 10 increases, resulting in a higher saturation temperature of the semiconductor element 2. Along with the increase in the saturation temperature of the semiconductor element 2, the saturation temperature of the wiring 8 also increases, resulting in an increase in the value of V1. Furthermore, with the increase in the value of V1, the slope of the curve representing the transitional change in the value of Vee from t0 to t1 increases.

[0071] like Figure 7 As shown, the value of V0 is the same regardless of the degree of degradation of the bonding material 11. This is because the temperature of the wiring 8 did not rise at time point t0.

[0072] The third insight is regarding the relationship between the degradation of the bonding material 11 and the junction 12, and the waveform of Vee, in relation to the degradation of the semiconductor module 1. The inventors fabricated multiple samples of the semiconductor module 1 with different combinations of degradation degrees of the bonding material 11 and the junction 12, simulating the degradation state of these materials. Furthermore, Vee was measured for these samples, and the waveform of Vee was compared for each sample. As a result, the inventors obtained the following insight: the value of V1 is sometimes consistent even with different combinations of degradation degrees of the bonding material 11 and the junction 12.

[0073] Figure 8 This is a graph illustrating an example of the waveform of the Vee of the semiconductor module 1, showing the degradation of the bonding material 11 and the bonding portion 12. Figure 8 The graph shows two waveforms, c1 and c2, superimposed. The dashed waveform c1 represents the case where the degradation of the joint 12 is small and the degradation of the bonding material 11 is large. The solid waveform c2 represents the case where the degradation of the joint 12 is large and the degradation of the bonding material 11 is small.

[0074] V1 is a value obtained by adding V0 to the increase in Vee associated with the temperature rise of wiring 8. In other words, V1 is a value reflecting the deterioration of both the bonding material 11 and the joint 12. Furthermore, as... Figure 8 As shown, the V1 value in the case where the degree of deterioration of the joint 12 is small and the degree of deterioration of the bonding material 11 is large (waveform c1) is sometimes the same as the V1 value in the case where the degree of deterioration of the joint 12 is large and the degree of deterioration of the bonding material 11 is small (waveform c2).

[0075] Therefore, for example, in the case of detecting the degradation of semiconductor module 1 based on whether the value of V1 reaches a preset threshold, as in the conventional case, it is possible to know that either or both of the bonding material 11 and the junction 12 are degraded. However, as in this example, in a method that only measures the voltage after a certain period of time since the main current has flowed in semiconductor module 1, it is impossible to know exactly which of the bonding material 11 and the junction 12 is degraded to what extent.

[0076] The above explains the insights gained through the inventor's dedicated research. Next, a method for diagnosing the degradation of semiconductor module 1, discovered based on the first to third insights, will be described.

[0077] First, a method for diagnosing the deterioration of the joint 12 will be explained. As described in the first perspective, the value of V0 increases with the degree of deterioration of the joint 12. Furthermore, as described in the second perspective, the value of V0 is independent of the degree of deterioration of the bonding material 11. Therefore, the deterioration of the joint 12 can be diagnosed based on the measurement result of V0.

[0078] Regarding the degradation diagnosis of the junction 12 based on the measurement results of V0, specifically, by comparing the V0 (hereinafter referred to as V0_n) of the semiconductor module 1 under diagnosis with the V0 (hereinafter referred to as V0_ini) under the healthy state of the semiconductor module 1, the degradation of the junction 12 of the semiconductor module 1 under diagnosis can be diagnosed.

[0079] The comparison between V0_n and V0_ini can be made either by using the difference between V0_n and V0_ini, or by using the ratio between V0_n and V0_ini.

[0080] Furthermore, the deterioration of the joint 12 can be diagnosed by comparing V0_n with a pre-set reference value of V0 (hereinafter referred to as V0_ref) instead of comparing it with V0_ini. The comparison between V0_n and V0_ref is similar to the comparison between V0_n and V0_ini; it can be a comparison using the difference between V0_n and V0_ref, or a comparison using the ratio between V0_n and V0_ref.

[0081] Here, in order to diagnose the deterioration of the junction 12 with high accuracy, it is preferable to measure V0 with high accuracy. As mentioned above, V0 is the voltage value at which Vee rises sharply immediately after the main current flows into the semiconductor module 1 at time t0 (refer to...). Figure 5 Furthermore, the value of Vee gradually increases as the temperature of wiring 8 rises.

[0082] Therefore, the preferred timing for measuring V0 is before Vee rises sharply to a certain value and the temperature of wiring 8 begins to rise. The method for measuring V0 at such timing is not particularly limited; one example is receiving a gate drive signal to turn on the semiconductor element 2 and using the time of receiving the gate drive signal as a reference. In this method, Vee is measured after a predetermined delay time from the time the gate drive signal is received, and its value is set as V0. That is, by appropriately adjusting the predetermined delay time, V0 can be measured with high precision.

[0083] Another example of a method for adjusting the timing of V0 measurement can be a method utilizing the electrical characteristics that change instantaneously when the semiconductor element 2 becomes on. Such electrical characteristics could include, for example, gate voltage, Vee, or mains current. Specifically, for example, using the time when the gate voltage reaches a predetermined threshold as a reference, Vee is measured after a predetermined delay time from that time point, and its value is set as V0.

[0084] Alternatively, a sharp rise in Vee can be detected by monitoring Vee at a higher sampling rate and performing a differential operation on the monitored Vee, and the voltage value V0 at the point of sharp rise in Vee can be measured.

[0085] Next, a method for diagnosing the deterioration of the bonding material 11 will be explained. As described in the explanation of the third view, V1 is a value reflecting the deterioration of both the bonding material 11 and the joint 12. Furthermore, as mentioned above, the deterioration of the joint 12 can be diagnosed based on the measurement result of V0. Therefore, regarding V1, if the contribution of the deterioration of the joint 12 obtained based on the measurement result of V0 is eliminated, the deterioration of the bonding material 11 can be diagnosed. That is, the deterioration of the bonding material 11 can be diagnosed based on the comparison of V0 and V1.

[0086] Reference Figure 9 This illustrates the degradation diagnosis of the bonding material 11 based on the comparison of V0 and V1. Figure 9 This is a graph illustrating an example of the waveform of Vee in semiconductor module 1 that has undergone some degree of degradation. Figure 9The graph shows two waveforms, d1 and d2, superimposed. The dashed line representing waveform d1 indicates the Vee waveform of the semiconductor module 1 in a healthy state. The solid line representing waveform d2 indicates the Vee waveform of the semiconductor module 1 when the bonding material 11 and the bonding portion 12 have deteriorated. Additionally, Figure 9 The V1_n shown represents V1 of the semiconductor module 1 of the diagnostic object. Figure 9 The V1_ini shown represents V1 in the healthy state of semiconductor module 1.

[0087] First, by comparing V1_n and V1_ini, the degradation of the semiconductor module 1 caused by the degradation of the bonding material 11 and the bonding portion 12 can be determined. Furthermore, based on the comparison results, the contribution of the degradation of the bonding portion 12 obtained by comparing V0_n and V0_ini is eliminated, thereby enabling the diagnosis of the degradation of the bonding material 11.

[0088] More specifically, the degradation of the bonding material 11 can be diagnosed by comparing the differences between V1_n and V1_ini, and the differences between V0_n and V0_ini. Furthermore, the degradation of the bonding material 11 can also be diagnosed by comparing the ratios of V1_n and V1_ini, and the ratios of V0_n and V0_ini. Moreover, the comparisons of the differences between V1_n and V1_ini, and the differences between V0_n and V0_ini, as well as the comparisons of the ratios of V1_n and V1_ini, and V0_n and V0_ini, can be based on either differences or division operations.

[0089] Alternatively, the deterioration of the bonding material 11 can be diagnosed by comparing the difference between V1_ini and V0_ini and the difference between V1_n and V0_n, or by comparing the ratio of V1_ini to V0_ini and the ratio of V1_n to V0_n. The comparison method in this case can be either difference or division.

[0090] Alternatively, instead of V1_ini, the degradation of the bonding material 11 can be diagnosed by performing calculations using V1_ref, which is a pre-set reference value for V1. For example, the degradation of the bonding material 11 can also be diagnosed by comparing the difference between V1_ref and V0_ref and the difference between V1_n and V0_n, or by comparing the ratio of V1_ref to V0_ref and the ratio of V1_n to V0_n. The comparison method in this case can be either difference or division.

[0091] Here, the timing for measuring V1 is explained. Using t0 as a reference, V1 is measured at t1, which is the time after the temperature saturation of wiring 8 and the convergence of the transient voltage rise of Vee. Alternatively, the convergence of the transient voltage rise of Vee can be detected by monitoring Vee and performing a differential operation on the monitored Vee, and V1 is measured at the time of convergence.

[0092] The above describes a method for diagnosing the degradation of semiconductor module 1, which was discovered based on insights gained through the inventor's dedicated research.

[0093] [1-2. Actions]

[0094] Next, the operation of the degradation diagnostic device 100 will be explained.

[0095] First, refer to Figure 1 as well as Figure 2 This indicates that in the deterioration diagnostic device 100, the joint 12 (refer to...) Figure 3 as well as Figure 4 The action is to diagnose the deterioration of ).

[0096] When semiconductor element 2 becomes conductive and main current begins to flow in semiconductor module 1 Figure 1 The voltage measurement unit 101 shown measures Vee (V0_n) at the first moment (t0) immediately after the main current flows into the semiconductor module 1.

[0097] like Figure 1 As shown, the voltage measurement unit 101 outputs V0_n to the diagnostic processing unit 102. Furthermore, as... Figure 2 As shown, the value of V0_n is input to the first arithmetic unit 103 of the diagnostic processing unit 102 and recorded in the first storage unit 106 of the diagnostic processing unit 102.

[0098] The first storage unit 106 records the value of V0 (V0_ini) in the healthy state of the semiconductor module 1.

[0099] The first arithmetic unit 103 reads V0_ini from the first storage unit 106, compares V0_n and V0_ini, and diagnoses the degradation state of the junction 12. The content of the degradation state diagnosis of the junction 12 performed by the first arithmetic unit 103 is not particularly limited. For example, the first arithmetic unit 103 may also output the difference between V0_n and V0_ini as information representing the diagnosis result of the degradation state of the junction 12. Alternatively, as another example, the first arithmetic unit 103 may determine whether the difference between V0_n and V0_ini exceeds a preset predetermined value and output its determination result.

[0100] Furthermore, the value recorded in the first storage unit 106 and compared with the value of V0_n in the first arithmetic unit 103 is not limited to V0_ini. For example, it could also be a value preset as a reference (V0_ref).

[0101] Next, refer to Figure 1 as well as Figure 2 This indicates that in the deterioration diagnostic device 100, the bonding material 11 (refer to...) Figure 3 The action is to diagnose the deterioration of ).

[0102] Figure 1 The voltage measurement unit 101 shown measures Vee (V1_n) at a second moment after the temperature saturation of wiring 8 and the transitional rise and convergence of Vee. Furthermore, at this second moment, semiconductor element 2 is in the on state, and main current flows through semiconductor module 1.

[0103] like Figure 1 As shown, the voltage measurement unit 101 outputs V1_n to the diagnostic processing unit 102. Furthermore, as... Figure 2 As shown, the value of V1_n is input to the second arithmetic unit 104 of the diagnostic processing unit 102.

[0104] The second arithmetic unit 104 reads V0_n from the first storage unit 106, performs a comparison operation on V1_n and V0_n, and calculates the comparison operation value V3_n. The comparison operation method of the second arithmetic unit 104 is, for example, the difference between V1_n and V0_n or the ratio between V1_n and V0_n. The second arithmetic unit 104 outputs the calculated comparison operation value V3_n to the third arithmetic unit 105.

[0105] Furthermore, the comparison operation value V3_ini calculated by the second arithmetic unit 104 through the comparison operation of the value of V1 (V1_ini) and the value of V0 (V0_ini) in the healthy state of the semiconductor module 1 is recorded in the second storage unit 107.

[0106] The third arithmetic unit 105 reads V3_ini from the second storage unit 107, compares V3_n and V3_ini, and diagnoses the deterioration state of the bonding material 11. Furthermore, regarding V3_n and V3_ini compared in the third arithmetic unit 105, the values ​​calculated using the same comparison operation method are employed. That is, for example, if V3_n is the value obtained by dividing V1_n by V0_n, the value obtained by dividing V1_ini by V0_ini is used as V3_ini.

[0107] The content of the diagnosis of the deterioration state of the bonding material 11 performed by the third calculation unit 105 is not particularly limited. For example, the third calculation unit 105 may also output the difference between V3_n and V3_ini as information indicating the diagnosis result of the deterioration state of the bonding material 11. Alternatively, as another example, the third calculation unit 105 may determine whether the difference between V3_n and V3_ini exceeds a preset predetermined value and output its determination result.

[0108] Furthermore, the value recorded in the second storage unit 107 and compared with the value of V3_n in the third arithmetic unit 105 is not limited to V3_ini. For example, it can also be a value (V3_ref) that has been preset as a reference.

[0109] [1-3. Effects, etc.]

[0110] As described above, in this embodiment, the degradation diagnosis device 100 is a device for diagnosing the degradation of a semiconductor module 1 having a semiconductor element 2. The semiconductor element 2 has a collector electrode 3a as a first main electrode and an emitter electrode 5a as a second main electrode. The degradation diagnosis device 100 includes: a voltage measurement unit 101 that measures the voltage between an emitter main terminal 5, which is electrically connected to the emitter electrode 5a via wiring 8, and an emitter reference terminal 6, which is a reference terminal for detecting the potential of the emitter electrode 5a; and a diagnosis processing unit 102 that diagnoses the degradation of the semiconductor module 1 based on the measurement results in the voltage measurement unit 101. The voltage measurement unit 101 measures a first voltage at a first moment immediately after the main current flows into the semiconductor module 1, and a second voltage at a second moment after the transitional rise and convergence of the voltage between the emitter main terminal 5 and the emitter reference terminal 6. The diagnosis processing unit 102 diagnoses the degradation of the bonding material 11 bonded to the collector electrode 3a based on the comparison of the first voltage and the second voltage.

[0111] Therefore, regarding the degradation diagnosis of semiconductor module 1, the degradation of bonding material 11 can be diagnosed separately. Furthermore, since the degradation of bonding material 11 can be diagnosed separately, the lifespan of semiconductor module 1 can be more accurately predicted compared to situations where it cannot be diagnosed separately, and more appropriate maintenance measures for semiconductor module 1 can be taken.

[0112] Furthermore, the diagnostic processing unit 102 is configured to diagnose the degradation of the semiconductor module 1 based on the measurement results from the voltage measurement unit 101, eliminating the need to measure the temperature of the semiconductor element 2. Therefore, there is no need to install a mechanism for measuring the temperature of the semiconductor element 2, which allows for miniaturization of both the degradation diagnostic device 100 and the semiconductor device 200 compared to the case where a mechanism for measuring the temperature of the semiconductor element 2 is included.

[0113] Furthermore, compared to the transitional rise of Vee, the second voltage can be measured more stably when the transitional voltage rise of Vee has converged to a stable state. Therefore, the degradation diagnosis device 100 according to this embodiment can diagnose the degradation of the bonding material 11 with high accuracy.

[0114] Furthermore, in this embodiment, the degradation diagnosis device 100 can be structured such that the diagnosis processing unit 102 diagnoses the degradation of the junction 12 between the wiring 8 and the emitter electrode 5a based on the value of the first voltage. That is, regarding the degradation diagnosis of the semiconductor module 1, the degradation of the bonding material 11 and the degradation of the junction 12 can be diagnosed separately.

[0115] Furthermore, in this embodiment, the diagnostic processing unit 102 can diagnose the deterioration of the bonding material 11 based on the first voltage (V0_n), the second voltage (V1_n), and a predetermined reference value. That is, as a method for diagnosing the deterioration of the bonding material 11 based on a comparison of the first and second voltages, a method based on the first voltage, the second voltage, and a predetermined reference value can be used. In this case, the predetermined reference value can also be a value set according to the first voltage (V0_ini) and the second voltage (V1_ini) under the healthy state of the semiconductor module 1.

[0116] Furthermore, in this embodiment, the following structure can be adopted: the diagnostic processing unit 102 diagnoses the deterioration of the bonding material 11 based on the result obtained by comparing a first voltage (V0_n) with a predetermined first reference value and the result obtained by comparing a second voltage (V1_n) with a predetermined second reference value. That is, as another way to diagnose the deterioration of the bonding material 11 based on the comparison of the first voltage and the second voltage, the deterioration diagnosis of the bonding material 11 based on the result obtained by comparing the first voltage with a predetermined first reference value and the result obtained by comparing the second voltage with a predetermined second reference value can be listed. In this case, the predetermined first reference value can also be a value set according to the first voltage (V0_ini) in the healthy state of the semiconductor module 1. In addition, the predetermined second reference value can also be a value set according to the second voltage (V1_ini) in the healthy state of the semiconductor module 1.

[0117] [1-4. Variations]

[0118] Reference Figure 10 as well as Figure 11 This describes a variation of Implementation Method 1.

[0119] In the degradation diagnosis device 100 of Embodiment 1, the structure is as follows: the voltage measuring unit 101 measures the voltage Vee, which is the difference between the potential of the emitter main terminal 5 and the potential of the emitter reference terminal 6. On the other hand, as Figure 10 As shown, a structure can also be used to measure the voltage Vce, which is the difference between the potential of the collector main terminal 3 and the potential of the emitter main terminal 5, using the voltage measurement unit 101.

[0120] Figure 10 This is a diagram showing a schematic structure of a semiconductor device 200 having a modified embodiment 100 of the degradation diagnostic apparatus 100. Figure 10 As shown, the collector main terminal 3 and the emitter main terminal 5 are connected to the voltage measurement unit 101. The voltage measurement unit 101 measures the voltage Vce, which is the difference between the potential of the collector main terminal 3 and the potential of the emitter main terminal 5, and outputs it to the diagnostic processing unit 102.

[0121] In the description of Implementation 1, the content described regarding the structure for measuring Vee remains the same even if Vee is replaced with Vce.

[0122] Therefore, in this embodiment, the following structure can be adopted: the degradation diagnosis device 100 is a device for diagnosing the degradation of a semiconductor module 1 having a semiconductor element 2, wherein the semiconductor element 2 has a collector electrode 3a as a first main electrode and an emitter electrode 5a as a second main electrode. The degradation diagnosis device 100 includes: a voltage measurement unit 101 that measures the voltage between a collector main terminal 3, which is electrically connected to the collector electrode 3a as a first main terminal, and an emitter main terminal 5, which is electrically connected to the emitter electrode 5a via wiring 8 as a second main terminal; and a diagnosis processing unit 102 that diagnoses the degradation of the semiconductor module 1 based on the measurement results in the voltage measurement unit 101. The voltage measurement unit 101 measures a first voltage at a first moment immediately after the main current flows into the semiconductor module 1, and a second voltage at a second moment after the transitional rise and convergence of the voltage between the collector main terminal 3 and the emitter main terminal 5. The diagnosis processing unit 102 diagnoses the degradation of the bonding material 11 bonded to the collector electrode 3a based on the comparison of the first voltage and the second voltage.

[0123] In the case of a structure that uses a voltage measuring unit 101 to measure voltage Vce, such as Figure 11 As shown, the degradation diagnostic device 100 can be applied to a semiconductor module 1 that does not have an emitter reference terminal 6.

[0124] Figure 11 This is a diagram illustrating other structural examples of a semiconductor device 200 having a modified embodiment 1 of the degradation diagnostic apparatus 100. (See diagram for details.) Figure 11 As shown, the semiconductor module 1 of the semiconductor device 200 does not have an emitter reference terminal 6.

[0125] Therefore, in this embodiment, the following structure can be adopted: the degradation diagnosis device 100 is a device for diagnosing the degradation of a semiconductor module 1 having a semiconductor element 2, wherein the semiconductor element 2 has a collector electrode 3a as a first main electrode and an emitter electrode 5a as a second main electrode, and the degradation diagnosis device 100 includes: a voltage measurement unit 101, which measures the voltage between the collector main terminal 3, which is electrically connected to the collector electrode 3a and is a first main terminal, and the emitter main terminal 5, which is electrically connected to the emitter electrode 5a via wiring 8 and is a second main terminal, or a reference terminal for detecting the potential of the emitter electrode 5a. The voltage between the emitter reference terminal 6 and the emitter main terminal 5; and the diagnostic processing unit 102, which diagnoses the degradation of the semiconductor module 1 based on the measurement results in the voltage measurement unit 101. The voltage measurement unit 101 measures the first voltage at the first moment after the main current flows into the semiconductor module 1 has just begun, and the second voltage at the second moment after the transitional rise and convergence of the voltage between the collector main terminal 3 and the emitter main terminal 5 or between the emitter main terminal 5 and the emitter reference terminal 6. The diagnostic processing unit 102 diagnoses the degradation of the bonding material 11 bonded to the collector electrode 3a based on the comparison of the first voltage and the second voltage.

[0126] Implementation method 2.

[0127] Reference Figures 12 to 14 Regarding Implementation Method 2, the main differences from Implementation Method 1 will be explained.

[0128] [2-1. Structure]

[0129] Figure 12 This is a diagram showing a schematic structure of a semiconductor device 210 equipped with the degradation diagnostic device 110 of Embodiment 2. Figure 13 This is a diagram showing the schematic structure of the diagnostic processing unit 112 included in the degradation diagnostic device 110 of Embodiment 2. Figure 14 This is a graph illustrating the method for diagnosing the degradation of semiconductor module 1 in Embodiment 2.

[0130] like Figure 12 as well as Figure 13 As shown, the structure of the degradation diagnosis device 110 in Embodiment 2 is the same as that of the degradation diagnosis device 100 in Embodiment 1, but the functions and operations of some parts of the structure are different. The functions and operations that are different from those of the degradation diagnosis device 100 in Embodiment 1 will be explained in the description of the operation later.

[0131] Reference Figure 14 This describes a method for diagnosing the degradation of semiconductor module 1 in embodiment 2. Figure 14 and Figure 9Similarly, an example of the waveform of Vee in semiconductor module 1 that has undergone some degree of degradation is shown.

[0132] exist Figure 14 The graph shows two waveforms, e1 and e2, superimposed. Waveform e1, indicated by the dashed line, represents the Vee waveform of the semiconductor module 1 in a healthy state. Waveform e2, indicated by the solid line, represents the Vee waveform of the semiconductor module 1 where the bonding material 11 and the bonding portion 12 have deteriorated. Regarding waveform e1, the measured value of Vee at time t0 is V0_ini, at time ta is Va_ini, at time tb is Vb_ini, and at time t1 is V1_ini. Similarly, regarding waveform e2, the measured value of Vee at time t0 is V0_n, at time ta is Va_n, at time tb is Vb_n, and at time t1 is V1_n.

[0133] As described in the second perspective of the description of Embodiment 1, the voltage rise (slope of the voltage waveform) after Vee reaches V0 until it reaches V1 varies depending on the degree of degradation of the bonding material 11. Therefore, it is possible to base... Figure 14 The comparison of Va and Vb shown is used to diagnose the degradation of the bonding material 11. Va is the value of Vee measured at ta after t0. ta is an arbitrary time determined during the period from t0 to t1. Vb is the value of Vee measured at tb after ta. tb is an arbitrary time determined during the period from t0 to t1, after ta.

[0134] Regarding the degradation diagnosis of the bonding material 11 based on the comparison of Va and Vb, specifically, for example, the degree of degradation of the bonding material 11 can be diagnosed by comparing the difference between Vb_n and Va_n and the difference between Vb_ini and Va_ini. However, the method for diagnosing the degradation of the bonding material 11 based on the comparison of Va and Vb is not limited to this; any method based on an index reflecting the slope from ta to tb of waveform e2 is acceptable.

[0135] Furthermore, it is not necessary to use the healthy waveform e1 as a reference for diagnosis; any arbitrarily set reference can be used. For example, the degree of degradation of the bonding material 11 can be diagnosed based on whether the difference between Vb_n and Va_n exceeds a preset threshold.

[0136] Furthermore, Va and Vb do not necessarily have to be voltage values ​​measured during the transitional rise of Vee. Of Va and Vb, Va could also be the voltage value (V0) when Vee rises sharply immediately after the main current flows into semiconductor module 1, and Vb could be the voltage value measured during the transitional rise of Vee. Additionally, of Va and Vb, Va could also be the voltage value measured during the transitional rise of Vee, and Vb could be the voltage value (V1) measured after the transitional voltage rise of Vee converges.

[0137] [2-2. Action]

[0138] Next, the operation of the degradation diagnosis device 110 in Embodiment 2 will be explained.

[0139] Reference Figure 12 as well as Figure 13 This explains the deterioration diagnosis device 110 in Embodiment 2, which is used to test the bonding material 11 (refer to...). Figure 3 The procedure for diagnosing the deterioration of the joint 12 is the same as in Embodiment 1, so the description is omitted.

[0140] Figure 12 The voltage measurement unit 111 shown measures Vee (Va_n) at a second time ta after the first time t0, and Vee (Vb_n) at a third time tb after the second time ta. Furthermore, at the third time tb, the semiconductor element 2 is in the on state, and the main current flows through the semiconductor module 1. Here, as... Figure 12 As shown, the voltage measurement unit 111 measures Va and Vb during the transitional rise in temperature of wiring 8 and the transitional rise in Vee. However, Va can also be a voltage value (V0) measured immediately after the main current flows into semiconductor module 1. Similarly, Vb can be a voltage value (V1) measured after the transitional voltage rise in Vee converges.

[0141] like Figure 12 As shown, the voltage measurement unit 111 outputs Va_n and Vb_n to the diagnostic processing unit 112. Furthermore, as... Figure 13 As shown, the value of Va_n is input into the first storage unit 116 of the diagnostic processing unit 112 and recorded. The value of Vb_n is input into the second arithmetic unit 114 of the diagnostic processing unit 112.

[0142] The second arithmetic unit 114 reads Va_n from the first storage unit 116, performs a comparison operation on Vb_n and Va_n, and calculates the comparison operation value V4_n. The comparison operation method of the second arithmetic unit 114 is, for example, the difference between Vb_n and Va_n or the ratio between Vb_n and Va_n. The second arithmetic unit 114 outputs the calculated comparison operation value V4_n to the third arithmetic unit 115.

[0143] Furthermore, the comparison operation value V4_ini calculated by the second arithmetic unit 114 through the comparison operation of the value of Vb (Vb_ini) and the value of Va (Va_ini) in the healthy state of the semiconductor module 1 is recorded in the second storage unit 117.

[0144] The third arithmetic unit 115 reads V4_ini from the second storage unit 117, compares V4_n and V4_ini, and diagnoses the deterioration state of the bonding material 11. Furthermore, regarding V4_n and V4_ini compared in the third arithmetic unit 115, the values ​​calculated using the same comparison operation method are employed. That is, for example, if V4_n is the value obtained by dividing Vb_n by Va_n, then V4_ini uses the value obtained by dividing Vb_ini by Va_ini.

[0145] The content of the diagnosis of the degradation state of the bonding material 11 performed by the third calculation unit 115 is not particularly limited. For example, the third calculation unit 115 may also output the difference between V4_n and V4_ini as information indicating the diagnosis result of the degradation state of the bonding material 11. Alternatively, as another example, the third calculation unit 115 may determine whether the difference between V4_n and V4_ini exceeds a preset predetermined value and output its determination result.

[0146] Furthermore, the value recorded in the second storage unit 117 and compared with the value of V4_n in the third arithmetic unit 115 is not limited to V4_ini. For example, it can also be a value (V4_ref) that is preset as a reference.

[0147] [2-3. Effects, etc.]

[0148] As described above, in this embodiment, the voltage measurement unit 111 measures the first voltage at a first moment during the period when the main current begins to flow into the semiconductor module 1 and Vee rises transitionally, and the second voltage at a second moment after the first moment. The diagnostic processing unit 112 diagnoses the deterioration of the bonding material 11 bonded to the collector electrode 3a based on the comparison of the first voltage and the second voltage.

[0149] Therefore, similar to Embodiment 1, the degradation diagnosis of the semiconductor module 1 can be performed separately for the degradation of the bonding material 11.

[0150] In addition, similar to Embodiment 1, there is no need to provide a mechanism for measuring the temperature of the semiconductor element 2. Compared with the case where a mechanism for measuring the temperature of the semiconductor element 2 is provided, the degradation diagnostic device 110 and the semiconductor device 210 can be miniaturized.

[0151] When diagnosing the degradation of the bonding material 11 based on the slope of the gradually rising voltage waveform, a high slope of the voltage waveform allows for accurate diagnosis of the degradation of the bonding material 11. Therefore, the first and second moments are preferably close to the moment when the main current begins to flow into the semiconductor module 1.

[0152] In this embodiment, the first moment can also be the moment immediately after the main current begins to flow into the semiconductor module 1. In this case, the diagnostic processing unit 112 can diagnose the deterioration of the junction 12 between the wiring 8 and the emitter electrode 5a based on the value of the first voltage.

[0153] In this embodiment, the second moment can also be the moment after the transitional rising convergence of Vee.

[0154] In this embodiment, the following structure can be adopted: when the first moment is the moment immediately after the main current flows to the semiconductor module 1 and the second moment is the moment during the transitional rise of Vee, the voltage measurement unit 111 also measures the third voltage at the third moment after the second moment, and the diagnostic processing unit 112 diagnoses the deterioration of the bonding material 11 based on the comparison between the second voltage and the third voltage, and diagnoses the deterioration of the junction 12 of the wiring 8 and the emitter electrode 5a based on the value of the first voltage.

[0155] Furthermore, in this embodiment, the following structure can be adopted: the diagnostic processing unit 112 diagnoses the degradation of the bonding material 11 based on the second voltage (Va_n), the third voltage (Vb_n), and a predetermined reference value. That is, as a method of diagnosing the degradation of the bonding material 11 based on a comparison of the second voltage and the third voltage, a degradation diagnosis of the bonding material 11 based on the second voltage, the third voltage, and a predetermined reference value can be adopted. In this case, the predetermined reference value can also be a value set according to the second voltage (Va_ini) and the third voltage (Vb_ini) in the healthy state of the semiconductor module 1.

[0156] Furthermore, in this embodiment, the following structure can be adopted: the diagnostic processing unit 112 diagnoses the deterioration of the bonding material 11 based on the result obtained by comparing the second voltage (Va_n) with a predetermined first reference value and the result obtained by comparing the third voltage (Vb_n) with a predetermined second reference value. That is, as another way to diagnose the deterioration of the bonding material 11 based on the comparison of the second voltage and the third voltage, the deterioration diagnosis of the bonding material 11 based on the result obtained by comparing the second voltage with a predetermined first reference value and the result obtained by comparing the third voltage with a predetermined second reference value can be listed. In this case, the predetermined first reference value can also be a value set according to the second voltage (Va_ini) in the healthy state of the semiconductor module 1. In addition, the predetermined second reference value can also be a value set according to the third voltage (Vb_ini) in the healthy state of the semiconductor module 1.

[0157] Furthermore, in this embodiment, when the first moment is correlated with the moment immediately following the start of the main current flow to the semiconductor module 1, the second moment is correlated with the first moment, the second voltage is correlated with the first voltage, the third moment is correlated with the second moment, and the third voltage is correlated with the second voltage, it can be said that the diagnostic processing unit 112 diagnoses the degradation of the bonding material 11 bonded to the collector electrode 3a based on the comparison of the first voltage and the second voltage. The diagnostic processing unit 112 diagnoses the degradation of the junction 12 between the wiring 8 and the emitter electrode 5a based on the voltage value measured by the voltage measurement unit 111 at the moment immediately following the start of the main current flow to the semiconductor module 1. In this case, the first moment is the moment after the moment immediately following the start of the main current flow to the semiconductor module 1. In addition, the second moment is the moment during which the voltage between the collector main terminal 3 (which is the first main terminal) and the emitter main terminal 5 (which is the second main terminal), or the voltage between the emitter reference terminal 6 (which is the reference terminal) and the emitter main terminal 5 (which is the second main terminal), transitionally increases.

[0158] [2-4. Variations]

[0159] In Embodiment 2, a variation of Embodiment 1 can be used. That is, in Embodiment 2, the following structure can also be used: the voltage measuring unit 111 measures the voltage Vce, which is the difference between the potential of the collector main terminal 3 and the potential of the emitter main terminal 5.

[0160] Furthermore, in Embodiment 2, when the voltage Vce is measured using the voltage measurement unit 111, the degradation diagnostic device 110 can also be applied to a semiconductor module 1 that does not have an emitter reference terminal 6.

[0161] Therefore, in this embodiment, the following structure can be adopted: the voltage measurement unit 111 measures the first voltage at a first moment during the period when the main current flows to the semiconductor module 1 and Vce rises transitionally, and the second voltage at a second moment after the first moment; the diagnostic processing unit 112 diagnoses the deterioration of the bonding material 11 bonded to the collector electrode 3a based on the comparison of the first voltage and the second voltage.

[0162] Implementation method 3.

[0163] Reference Figures 15 to 17 Regarding Implementation Method 3, the main differences from Implementation Method 1 will be explained.

[0164] [3-1. Structure]

[0165] Figure 15 This is a diagram showing a schematic structure of a semiconductor device 220 equipped with the degradation diagnostic device 120 of embodiment 3. Figure 16 This is a diagram showing the schematic structure of the diagnostic processing unit 122 included in the degradation diagnostic device 120 of Embodiment 3. Figure 17 This is a graph illustrating the method for diagnosing the degradation of semiconductor module 1 in embodiment 3.

[0166] like Figure 15 as well as Figure 16 As shown, the structure of the degradation diagnosis device 120 in Embodiment 3 differs from that of the degradation diagnosis device 100 in Embodiment 1 in that the diagnosis processing unit 122 does not have a second storage unit. Furthermore, the functions and operations of some parts of the structure of the degradation diagnosis device 120 in Embodiment 3 and the degradation diagnosis device 100 in Embodiment 1 are different. The different functions and operations compared to the degradation diagnosis device 100 in Embodiment 1 will be explained in the subsequent description of the operations.

[0167] Reference Figure 17 This describes a method for diagnosing the degradation of semiconductor module 1 in embodiment 3. Figure 17 An example of the waveform of Vee-V0 (the value obtained by subtracting V0 from Vee) of semiconductor module 1 that has undergone some degree of degradation is shown.

[0168] exist Figure 17 The graph shows two waveforms, f1 and f2, superimposed. The dashed line f1 represents the Vee-V0 waveform of the semiconductor module 1 in a healthy state. The solid line f2 represents the Vee-V0 waveform of the semiconductor module 1 when the bonding material 11 and the bonding portion 12 have deteriorated.

[0169] For either waveform f1 or f2, the Vee measured at time t0 is V0, so the value of the vertical axis at t0 becomes 0. The vertical axis of the graph represents k, a reference value preset for diagnosing the degradation of the bonding material 11. The value of k can be arbitrarily set in a way that can properly diagnose the degradation of the bonding material 11. Here, as an example, the case where k is the value obtained by subtracting V0 from V1 of the semiconductor module 1 in a healthy state (V1 - V0) is shown.

[0170] Regarding waveform f1, at time t1 when V1 is measured, the value of Vee-V0 becomes k. In other words, regarding waveform f1, the time when the value of Vee-V0 becomes k is time t1. Furthermore, regarding waveform f2, the time when the value of Vee-V0 becomes k is time tc.

[0171] like Figure 17 As shown, with the deterioration of the bonding material 11, the slope of the Vee-V0 waveform increases after t0, and the time when Vee-V0 becomes k is close to t0. Therefore, it is possible to base... Figure 17 The comparison of tc and t0 shown is used to diagnose the deterioration of the bonding material 11.

[0172] Regarding the degradation diagnosis of the bonding material 11 based on the comparison of tc and t0, specifically, for example, the degree of degradation of the bonding material 11 can be diagnosed based on the difference between tc and t0.

[0173] In addition, Figure 17 In the graph, the vertical axis is set to Vee-V0 to remove the effects caused by the deterioration of the joint 12 from the measured Vee. The method for removing the effects caused by the deterioration of the joint 12 from the measured Vee is not limited to subtracting V0 from Vee. For example, the effects caused by the deterioration of the joint 12 can also be removed from the measured Vee by dividing Vee by V0.

[0174] [3-2. Action]

[0175] Next, the operation of the degradation diagnosis device 120 in Embodiment 3 will be explained.

[0176] Reference Figure 15 as well as Figure 16 This explains the deterioration diagnosis device 120 in Embodiment 3, which is used to test the bonding material 11 (refer to...). Figure 3 The procedure for diagnosing the deterioration of the joint 12 is the same as in Embodiment 1, so the description is omitted.

[0177] Figure 15The voltage measurement unit 121 shown measures Vee at a predetermined sampling rate after the first time t0 and outputs the measured Vee value to the diagnostic processing unit 122.

[0178] like Figure 16 As shown, the value of the first voltage V0_n measured at the first time t0 is input to the first storage unit 126 of the diagnostic processing unit 122 and recorded together with the information at the first time t0. Additionally, the value of Vee measured after the first time t0 is input to the second arithmetic unit 124.

[0179] The second arithmetic unit 124 reads and stores the value of V0_n from the first storage unit 126. Whenever the value of Vee is input from the voltage measurement unit 121, it performs a comparison operation between the value of Vee and V0_n. The comparison operation between Vee and V0_n in the second arithmetic unit 124 is, for example, a difference operation or a division operation. The second arithmetic unit 124 outputs information about the second time tc when the calculated comparison value reaches a preset reference value k to the third arithmetic unit 125. Here, the second time tc can also be referred to as the time when the second voltage Vk, which is greater than or equal to the preset reference value k, is measured in the voltage measurement unit 121.

[0180] The third arithmetic unit 125 reads the information of the first time t0 from the first storage unit 126, compares the first time t0 with the second time tc, and diagnoses the deterioration state of the bonding material 11. The content of the diagnosis of the deterioration state of the bonding material 11 performed by the third arithmetic unit 125 is not particularly limited. For example, the third arithmetic unit 125 may also output the difference between the first time t0 and the second time tc as information representing the diagnosis result of the deterioration state of the bonding material 11. Alternatively, as another example, the third arithmetic unit 125 may determine whether the length of the time difference between the first time t0 and the second time tc is less than a preset time length and output its determination result.

[0181] [3-3. Effects, etc.]

[0182] As described above, in this embodiment, the voltage measurement unit 121 measures the voltage after the first moment immediately following the start of the main current flow to the semiconductor module 1, and the diagnostic processing unit 122 compares the voltage measured in the voltage measurement unit 121 at a second moment based on the first moment and the result of comparing the voltage with the first voltage to a preset reference value, and diagnoses the deterioration of the bonding material 11 that is bonded to the collector electrode 3a.

[0183] Therefore, similar to Embodiment 1, the degradation diagnosis of the semiconductor module 1 can be performed separately for the degradation of the bonding material 11.

[0184] In addition, similar to Embodiment 1, there is no need to provide a mechanism for measuring the temperature of the semiconductor element 2. Compared with the case where a mechanism for measuring the temperature of the semiconductor element 2 is provided, the degradation diagnostic device 120 and the semiconductor device 220 can be miniaturized.

[0185] Furthermore, the change in the slope of the Vee waveform accompanying the deterioration of the bonding material 11 has the following characteristics: it is large in the initial stage when the degree of deterioration is small, and decreases as the degree of deterioration increases. When the slope of the Vee waveform changes significantly, the second time point tc in this embodiment also changes significantly. Therefore, the deterioration diagnosis device 120 according to this embodiment can diagnose the initial stage of deterioration of the bonding material 11 with high accuracy.

[0186] Furthermore, the reference value k, which is preset for diagnosing the deterioration of the bonding material 11, can be calculated by comparing V0 (V0_ini) and V1 (V1_ini) in the healthy state of the semiconductor module 1. In this case, an appropriate reference value k can be easily set for each semiconductor module to be diagnosed.

[0187] [3-4. Variations]

[0188] In Embodiment 3, a variation of Embodiment 1 can be used. That is, in Embodiment 3, the following structure can also be used: the voltage measuring unit 121 measures the voltage Vce, which is the difference between the potential of the collector main terminal 3 and the potential of the emitter main terminal 5.

[0189] Furthermore, in Embodiment 3, when the voltage Vce is measured using the voltage measurement unit 121, the degradation diagnostic device 120 can also be applied to a semiconductor module 1 that does not have an emitter reference terminal 6.

[0190] The above describes implementation method 3. Finally, refer to Figure 18 The hardware structure examples of the diagnostic processing unit 102 in Embodiment 1, the diagnostic processing unit 112 in Embodiment 2, and the diagnostic processing unit 122 in Embodiment 3 will be described below. Furthermore, the hardware structure example of the diagnostic processing unit 102 in Embodiment 1 will be described representatively below. The hardware structure examples of the diagnostic processing unit 112 in Embodiment 2 and the diagnostic processing unit 122 in Embodiment 3 are the same as the hardware structure example of the diagnostic processing unit 102 in Embodiment 1.

[0191] Figure 18 This is a diagram showing an example of the hardware structure of the diagnostic processing unit 102. (See diagram for example.) Figure 18As shown, the diagnostic processing unit 102 includes a processor 102a and a storage device 102b. For example, the degradation diagnosis of the semiconductor module 1 based on the measurement results in the voltage measurement unit 101 is implemented by the processor 102a and the storage device 102b.

[0192] Processor 102a is a device that executes programs stored in storage device 102b. Processor 102a is also referred to as a central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, processor, or DSP. Processor 102a may also have storage device 102b built into it.

[0193] The functions of the diagnostic processing unit 102 are implemented through software, firmware, or a combination of software and firmware. The software and firmware are described as programs and stored in the storage device 102b. The processor 102a implements the functions of the diagnostic processing unit 102 by reading and executing the programs stored in the storage device 102b.

[0194] Here, storage device 102b can also be non-volatile or volatile semiconductor memory such as RAM, ROM, flash memory, EPROM, EEPROM, disk, floppy disk, optical disk, high-density disk, mini disk, DVD, etc. RAM is short for Random Access Memory. ROM is short for Read Only Memory. EPROM is short for Erasable Programmable Read Only Memory. EEPROM is short for Electrically Erasable Programmable Read-Only Memory.

[0195] Alternatively, the processor 102a can also be dedicated hardware. In this case, the processor 102a can be, for example, a single circuit, a composite circuit, a programmable processor, or a processor programmed in parallel. Furthermore, the processor 102a can also be an ASIC (Application Specific Integrated Circuit) or a FPGA (Field-Programmable Gate Array). Moreover, the processor 102a can also be a combination of these.

[0196] Alternatively, the multiple functions of the diagnostic processing unit 102 can be implemented using separate diagnostic processing units. Alternatively, the multiple functions can be combined and implemented using a single diagnostic processing unit.

[0197] Furthermore, some of the functions of the diagnostic processing unit 102 can be implemented using dedicated hardware, and others can be implemented using software or firmware. In this way, the aforementioned functions can be implemented in the diagnostic processing unit 102 through hardware, software, firmware, or a combination thereof.

[0198] The above describes embodiments 1 to 3 of this disclosure. This disclosure is not limited to the above examples, and design changes can be appropriately made within the scope of satisfying the structure of this disclosure. For example, it may involve modifying at least one structure of this disclosure, adding at least one structure of this disclosure, omitting at least one structure of this disclosure, or extracting at least one constituent element and combining it with constituent elements of other embodiments.

[0199] Explanation of symbols

[0200] 1: Semiconductor module; 2: Semiconductor element; 3: Collector main terminal (first main terminal); 3a: Collector electrode (first main electrode); 4: Gate terminal; 5: Emitter main terminal (second main terminal); 5a: Emitter electrode (second main electrode); 6: Emitter reference terminal (reference terminal); 7: Collector main current wiring; 8: Emitter main current wiring (wiring); 9: Emitter reference wiring; 10: Conductive component; 11: Bonding material; 12: Junction; 13: Parasitic resistance component on the collector side; 14: Parasitic resistance component on the emitter side. Parasitic resistance components; 100, 110, 120: Deterioration diagnostic device; 101, 111, 121: Voltage measurement unit; 102, 112, 122: Diagnostic processing unit; 102a: Processor; 102b: Storage device; 103, 113, 123: First arithmetic unit; 104, 114, 124: Second arithmetic unit; 105, 115, 125: Third arithmetic unit; 106, 116, 126: First storage unit; 107, 117: Second storage unit; 200, 210, 220: Semiconductor device.

Claims

1. A degradation diagnostic device for diagnosing degradation of a semiconductor module having semiconductor elements, said semiconductor elements having a first main electrode and a second main electrode, wherein, The degradation diagnostic device includes: The voltage measurement unit measures the voltage between a first main terminal electrically connected to the first main electrode and a second main terminal electrically connected to the second main electrode via wiring, or the voltage between a reference terminal for detecting the potential of the second main electrode and the second main terminal. as well as The diagnostic processing unit diagnoses the degradation of the semiconductor module based on the measurement results from the voltage measurement unit. The voltage measurement unit measures a first voltage at a first moment during the period when the main current begins to flow into the semiconductor module and the voltage between the first main terminal and the second main terminal, or the voltage between the reference terminal and the second main terminal, transitionally rises, and a second voltage at a second moment after the first moment. The diagnostic processing unit diagnoses the degradation of the bonding material bonded to the first main electrode based on a comparison of the first voltage and the second voltage.

2. The degradation diagnostic device according to claim 1, wherein, The diagnostic processing unit diagnoses the deterioration of the bonding material based on the first voltage, the second voltage, and a predetermined reference value.

3. The degradation diagnostic device according to claim 1, wherein, The diagnostic processing unit diagnoses the deterioration of the bonding material based on the result obtained by comparing the first voltage with a predetermined first reference value and the result obtained by comparing the second voltage with a predetermined second reference value.

4. The degradation diagnostic device according to any one of claims 1 to 3, wherein, The first moment is the moment immediately after the main current has just begun flowing into the semiconductor module.

5. The degradation diagnostic device according to any one of claims 1 to 3, wherein, The second moment is the moment after the transitional rise and convergence of the voltage between the first main terminal and the second main terminal, or the voltage between the reference terminal and the second main terminal.

6. The degradation diagnostic device according to claim 4, wherein, The second moment is the moment after the transitional rise and convergence of the voltage between the first main terminal and the second main terminal, or the voltage between the reference terminal and the second main terminal.

7. A degradation diagnostic apparatus for diagnosing degradation of a semiconductor module having semiconductor elements, said semiconductor elements having a first main electrode and a second main electrode, wherein, The degradation diagnostic device includes: The voltage measurement unit measures the voltage between a first main terminal electrically connected to the first main electrode and a second main terminal electrically connected to the second main electrode via wiring, or the voltage between a reference terminal for detecting the potential of the second main electrode and the second main terminal. as well as The diagnostic processing unit diagnoses the degradation of the semiconductor module based on the measurement results from the voltage measurement unit. The voltage measurement unit measures the voltage from the moment immediately following the start of the main current flow into the semiconductor module. The diagnostic processing unit diagnoses the degradation of the bonding material bonded to the first main electrode based on a comparison of the first time and the second time, wherein the second time is the time when a voltage above a preset reference value is measured in the voltage measuring unit, which is the result of comparing the first voltage measured at the first time with the voltage measured at the first time.

8. The degradation diagnostic device according to claim 7, wherein, The diagnostic processing unit diagnoses the degradation of the bonding material bonded to the first main electrode based on the difference between the first time and the second time.

9. The degradation diagnostic device according to claim 7 or 8, wherein, When the voltage between the first main terminal and the second main terminal, or the voltage between the reference terminal and the second main terminal, converges after a transient rise, is set as the second voltage, The reference value is calculated based on a comparison of the first voltage and the second voltage under the healthy condition of the semiconductor module.

10. The degradation diagnostic device according to claim 4 or any one of 6 to 9, wherein, The diagnostic processing unit diagnoses the deterioration of the junction between the wiring and the second main electrode based on the value of the first voltage.

11. The degradation diagnostic device according to claim 1, wherein, The first moment is the moment immediately following the start of the main current flow into the semiconductor module. The second moment is a moment during the period when the voltage between the first main terminal and the second main terminal, or the voltage between the reference terminal and the second main terminal, transitionally increases. The voltage measurement unit measures the voltage between the first main terminal and the second main terminal, or the voltage between the reference terminal and the second main terminal, immediately after the main current begins to flow into the semiconductor module. The diagnostic processing unit diagnoses the deterioration of the junction between the wiring and the second main electrode based on the voltage value measured by the voltage measurement unit at a moment immediately after the main current flows to the semiconductor module, which is either the voltage between the first main terminal and the second main terminal or the voltage between the reference terminal and the second main terminal.

12. The degradation diagnostic device according to claim 11, wherein, The diagnostic processing unit diagnoses the deterioration of the bonding material based on the first voltage, the second voltage, and a predetermined reference value.

13. The degradation diagnostic device according to claim 11, wherein, The diagnostic processing unit diagnoses the deterioration of the bonding material based on the result obtained by comparing the first voltage with a predetermined first reference value and the result obtained by comparing the second voltage with a predetermined second reference value.

14. A semiconductor device comprising: The degradation diagnostic device according to any one of claims 1 to 13; and Semiconductor modules are the targets of degradation diagnosis.

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