Deterioration diagnosis device and semiconductor device comprising same

Abstract

A deterioration diagnosis device (100) comprises: a voltage measurement unit (101) that measures the voltage between a first main terminal (3) and a second main terminal (5) of a semiconductor module (1), or the 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) on the basis of the measurement results from the voltage measurement unit (101), wherein the voltage measurement unit (101) measures a first voltage at a first time which is immediately after the commencement of conduction of a main current to the semiconductor module (1), and a second voltage at a second time which is after the first time, and on the basis of a comparison between the first voltage and the second voltage, the diagnosis processing unit (102) diagnoses deterioration of a bonding material (11) that is bonded to a first main electrode (3a) of a semiconductor element (2) with which the semiconductor module (1) is provided.

Description

Degradation diagnosis device and semiconductor device equipped with the same

[0001] The present disclosure relates to a degradation diagnostic device for diagnosing degradation of a semiconductor module and a semiconductor device including the same.

[0002] As a technology for detecting deterioration of a semiconductor module, for example, a deterioration detection device is known that includes a monitoring unit that monitors an input value that changes in response to the detected value of the voltage between the collector terminal and the emitter terminal in the on state, and that includes a low-pass filter that performs low-pass filtering on the input value (Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2023-109223

[0004] Representative aspects of semiconductor module degradation include degradation of the bonding material and degradation of the wiring joint. Degradation of the bonding material refers to the occurrence of cracks in the bonding material between a first main electrode of a semiconductor element included in the semiconductor module and a conductive member electrically connected to the first main electrode. Degradation of the wiring joint refers to the occurrence of cracks in the joint between the second main electrode of the semiconductor element and the wiring joined to the second main electrode.

[0005] According to conventional techniques (for example, Patent Document 1), it was possible to detect deterioration of at least one of the bonding material and the wiring joint, or deterioration of both, but it was not possible to diagnose the deterioration of the bonding material separately.

[0006] The invention disclosed herein has been made in consideration of these circumstances, and aims to provide a degradation diagnosis device that can individually diagnose the degradation of bonding materials in semiconductor modules, and a semiconductor device equipped with the same.

[0007] A degradation diagnosis device according to one aspect of the present disclosure is a degradation diagnosis device that diagnoses degradation of a semiconductor module including a semiconductor element having a first main electrode and a second main electrode, and includes a voltage measurement unit that 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, or the voltage between a reference terminal that detects the potential of the second main electrode and the second main terminal, and a diagnostic processing unit that diagnoses degradation of the semiconductor module based on the measurement results of the voltage measurement unit, wherein the voltage measurement unit measures a first voltage at a first time during a period in which a main current is started to flow through 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 transiently increases, and a second voltage at a second time after the first time, and the diagnostic processing unit diagnoses degradation of a bonding material bonded to the first main electrode based on a comparison between the first voltage and the second voltage.

[0008] Another aspect of the present disclosure provides a degradation diagnosis device for diagnosing degradation of a semiconductor module including a semiconductor element having a first main electrode and a second main electrode, the degradation diagnosis device comprising: a voltage measurement unit that 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, or the voltage between a reference terminal that detects the potential of the second main electrode and the second main terminal; and a diagnostic processing unit that diagnoses degradation of the semiconductor module based on the measurement results of the voltage measurement unit, wherein the voltage measurement unit measures the voltage after a first time point immediately after the flow of main current to the semiconductor module begins, and the diagnostic processing unit diagnoses degradation of the bonding material bonded to the first main electrode based on a comparison between the first time point and a second time point at which the voltage measurement unit measures a voltage whose result compared with the first voltage measured at the first time point is greater than or equal to a predetermined reference value.

[0009] According to the degradation diagnostic device according to one aspect of the present disclosure, it is possible to individually diagnose the degradation of bonding materials of semiconductor modules.

[0010] 1 is a diagram showing a schematic configuration of a semiconductor device including a degradation diagnosis device according to a first embodiment. FIG. 2 is a diagram showing a schematic configuration of a diagnosis processing unit included in the degradation diagnosis device according to the first embodiment. FIG. 3 is a diagram showing a cross-sectional structure of a semiconductor module that is a diagnosis target of the degradation diagnosis device according to the first embodiment. FIG. 4 is an enlarged view of part A shown in FIG. 3. FIG. 5 is a graph showing an example of a waveform of Vee in a state where the semiconductor module is not degraded. FIG. 6 is a graph showing an example of a waveform of Vee of a semiconductor module in which only the bonding portion has deteriorated. FIG. 7 is a graph showing an example of a waveform of Vee of a semiconductor module in which only the bonding material has deteriorated. FIG. 8 is a graph showing an example of a waveform of Vee of a semiconductor module in which the bonding material and the bonding portion have deteriorated. FIG. 9 is a graph showing an example of a waveform of Vee of a semiconductor module in which a certain degree of deterioration has occurred. FIG. 10 is a diagram showing a schematic configuration of a semiconductor device including a degradation diagnosis device according to a modification of the first embodiment. FIG. 11 is a diagram showing another example configuration of a semiconductor device including a degradation diagnosis device according to a modification of the first embodiment. FIG. 12 is a diagram showing a schematic configuration of a semiconductor device including a degradation diagnosis device according to a second embodiment. FIG. 13 is a diagram showing a schematic configuration of a diagnosis processing unit included in the degradation diagnosis device according to the second embodiment. FIG. 14 is a graph for explaining a method of diagnosing degradation of a semiconductor module in the second embodiment. 10 is a diagram showing a schematic configuration of a diagnostic processing unit included in the degradation diagnosis device according to embodiment 3. FIG. 11 is a graph for explaining a method of diagnosing degradation of a semiconductor module according to embodiment 3. FIG. 12 is a diagram showing an example of the hardware configuration of the diagnostic processing unit.

[0011] A degradation diagnosis device according to an embodiment of the present disclosure will be described below with reference to the drawings. Note that the drawings are schematic illustrations, and the dimensional ratios and the number of components in the drawings do not necessarily match the actual dimensional ratios and the number of components.

[0012] In addition, in the description of the embodiments of the present disclosure, duplicated descriptions of substantially identical configurations may be omitted. Also, detailed descriptions of already well-known matters may be omitted. These are intended to avoid the following description from becoming unnecessarily redundant and to facilitate understanding by those skilled in the art.

[0013] First Embodiment A first embodiment will be described with reference to FIGS.

[0014] 1 is a diagram showing a schematic configuration of a semiconductor device 200 including a degradation diagnosis device 100 according to embodiment 1. As shown in FIG. 1, semiconductor device 200 includes a semiconductor module 1 and degradation diagnosis device 100.

[0015] 1, the semiconductor module 1 includes a semiconductor element 2, a collector main terminal 3 which is a first main terminal, a gate terminal 4 which is a control terminal, an emitter main terminal 5 which is a second main terminal, and an emitter reference terminal 6 which is a reference terminal. As shown in Fig. 1, the collector main terminal 3, the gate terminal 4, the emitter main terminal 5, and the emitter reference terminal 6 are connected to the semiconductor element 2. The resistance shown between the semiconductor element 2 and the collector main terminal 3 represents a collector-side parasitic resistance component 13. The resistance shown between the semiconductor element 2 and the emitter main terminal 5 represents an emitter-side parasitic resistance component 14.

[0016] In this example, the semiconductor element 2 is an IGBT (Insulated-Gate Bipolar Transistor). However, the semiconductor element 2 included in the semiconductor module 1 is not limited to an IGBT. The semiconductor element 2 may be, for example, a MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor). When the semiconductor element 2 is a MOSFET, the collector may be read as the drain and the emitter as the source in the description of the embodiments of the present disclosure. In the following description, a case where the semiconductor element 2 is an IGBT will be described as an example.

[0017] The semiconductor element 2 operates in either an on state, in which a current flows between the collector main terminal 3 and the emitter main terminal 5, or an off state, in which no current flows between the collector main terminal 3 and the emitter main terminal 5. The on state and off state are switched depending on the voltage (gate voltage) applied between the gate terminal 4 and the emitter reference terminal 6. When the semiconductor element 2 is in the on state, a main current flows between the collector main terminal 3 and the emitter main terminal 5. In other words, the collector main terminal 3 and the emitter main terminal 5 are terminals through which the main current flows. On the other hand, no main current flows through the gate terminal 4 and the emitter reference terminal 6. The emitter reference terminal 6 is a reference terminal that detects the emitter potential of the semiconductor element 2.

[0018] As shown in FIG. 1, degradation diagnosis device 100 includes a voltage measurement unit 101 and a diagnosis processing unit 102.

[0019] The emitter main terminal 5 and the emitter reference terminal 6 are connected to a voltage measurement unit 101. The voltage measurement unit 101 measures a voltage Vee, which is the difference between the potential of the emitter main terminal 5 and the potential of the emitter reference terminal 6, and outputs the voltage Vee to a diagnostic processing unit 102.

[0020] The diagnostic processing unit 102 is connected to the voltage measurement unit 101. The diagnostic processing unit 102 diagnoses the deterioration of the semiconductor module 1 based on the measurement results of the voltage measurement unit 101. The connection between the voltage measurement unit 101 and the diagnostic processing unit 102 may be wired or wireless. If the connection between the voltage measurement unit 101 and the diagnostic processing unit 102 is wireless, the voltage measurement unit 101 and the diagnostic processing unit 102 each have a wireless communication function.

[0021] Fig. 2 is a diagram showing a schematic configuration of the diagnostic processing unit 102 included in the degradation diagnosis device 100 according to the first embodiment. As shown in Fig. 2, the diagnostic processing unit 102 includes a first calculation unit 103, a second calculation unit 104, a third calculation unit 105, a first storage unit 106, and a second storage unit 107. The functions of these units will be described together with the description of the operation to be given later.

[0022] Fig. 3 is a diagram showing a cross-sectional structure of semiconductor module 1, which is the target of diagnosis by degradation diagnosis device 100. Fig. 4 is an enlarged view of part A indicated by a dashed square in Fig. 3.

[0023] As shown in Fig. 3, the semiconductor module 1 includes a semiconductor element 2, a conductive member 10, a bonding material 11, a collector main terminal 3, an emitter main terminal 5, an emitter reference terminal 6, a collector main current wire 7, an emitter main current wire 8, and an emitter reference wire 9. The semiconductor module 1 also includes a gate terminal 4 as shown in Fig. 1. However, the gate terminal 4 is not shown in the cross-sectional view of Fig. 3.

[0024] As shown in FIG. 3, the semiconductor element 2 has a collector electrode 3a, which is a first main electrode, on one main surface, and an emitter electrode 5a, which is a second main electrode, on the other main surface.

[0025] 4, a joint 12 is formed between the emitter main current wire 8 (hereinafter also simply referred to as wire 8) and the emitter electrode 5a. The joint 12 is formed, for example, by solid-state bonding of the wire 8 and the emitter electrode 5a by ultrasonic thermocompression bonding.

[0026] The conductive member 10 shown in Fig. 3 is a layered or plate-shaped member made of a highly conductive material. As shown in Fig. 3, a semiconductor element 2 is disposed on the main surface of the conductive member 10. Examples of highly conductive materials that make up the conductive member 10 include aluminum, copper, alloys containing aluminum, and alloys containing copper. The conductive member 10 may also be a metal layer obtained by plating the surface of an insulating substrate.

[0027] 3 is a member that bonds the conductive member 10 and the collector electrode 3a. Examples of the bonding material 11 include solder and a conductive adhesive. An example of the conductive adhesive is silver paste.

[0028] 3 is a member that connects the conductive member 10 and the collector main terminal 3. The emitter main current wire 8 is a member that connects the emitter electrode 5a and the emitter main terminal 5. The emitter reference wire 9 is a member that connects the emitter electrode 5a and the emitter reference terminal 6. Examples of the collector main current wire 7, the emitter main current wire 8, and the emitter reference wire 9 include bonding wires and bonding ribbons. Examples of materials that make up the bonding wires and bonding ribbons include aluminum, copper, gold, and alloys containing at least one of these.

[0029] 3 , the collector electrode 3 a is joined to the conductive member 10 via a bonding material 11. The conductive member 10 is electrically connected to the collector main terminal 3 via the collector main current wire 7. That is, the collector electrode 3 a is electrically connected to the collector main terminal 3 via the bonding material 11. The emitter electrode 5 a is electrically connected to the emitter main terminal 5 via the emitter main current wire 8. The emitter electrode 5 a is electrically connected to the emitter reference terminal 6 via the emitter reference wire 9.

[0030] A collector-side parasitic resistance component 13 (see FIG. 1) exists between the collector main terminal 3 and the collector electrode 3a, and an emitter-side parasitic resistance component 14 (see FIG. 1) exists between the emitter main terminal 5 and the emitter electrode 5a.

[0031] Here, the deterioration of the semiconductor module 1 due to repeated operations of the semiconductor element 2 will be described.

[0032] When the semiconductor element 2 is in the on state, the main current flows, generating heat and increasing the temperature. When the semiconductor element 2 is switched from the on state to the off state, the semiconductor element 2 is cooled mainly by heat conduction to the conductive member 10 via the bonding material 11, and the temperature decreases.

[0033] When the temperature of the semiconductor element 2 fluctuates in this manner, thermal stress is applied to the connection points of the members connected to the semiconductor element 2 with the semiconductor element 2. When the semiconductor element 2 is repeatedly switched between an on state and an off state (hereinafter also simply referred to as an on / off operation), cracks may occur at the connection points with the semiconductor element 2 due to the applied thermal stress. The cracks that occur at the connection points with the semiconductor element 2 gradually grow in size as the on / off operation of the semiconductor element 2 is repeated.

[0034] Among the connection points between the semiconductor element 2 and the members connected to the semiconductor element 2, the bonding material 11 and the bonding portion 12, which are on the path of the main current and in contact with the semiconductor element 2, which is the heat source, have a higher frequency of crack occurrence and a higher degree of crack progression than other points. In other words, deterioration of either the bonding material 11 or the bonding portion 12, or both, is the main cause of deterioration of the semiconductor module 1.

[0035] Furthermore, as the deterioration of the semiconductor module 1 progresses, the electrical characteristics of the semiconductor module 1 change. Specifically, as the bonding material 11 deteriorates, the resistance value of the collector-side parasitic resistance component 13 (see FIG. 1) increases. Also, as the bonding portion 12 deteriorates, the resistance value of the emitter-side parasitic resistance component 14 (see FIG. 1) increases.

[0036] As described above, repeated on / off operation of the semiconductor element 2 causes deterioration of either the bonding material 11 or the bonding portion 12, or both, which causes deterioration of the semiconductor module 1, and as a result, the electrical characteristics of the semiconductor module 1 change.

[0037] Here, we will explain the findings obtained through the inventors' diligent research and the method of diagnosing deterioration of the semiconductor module 1 that was discovered based on this finding. The inventors created multiple types of samples of the semiconductor module 1 that simulated a degraded state, conducted experiments using these samples, and investigated in detail the relationship between the degradation of the semiconductor module 1 and changes in the electrical characteristics of the semiconductor module 1. The inventors then discovered that it is possible to individually diagnose the degree of degradation of either the bonding material 11 or the bonding portion 12 in the semiconductor module 1.

[0038] First, referring to Fig. 5, we will explain Vee, which is the voltage between the emitter main terminal 5 and the emitter reference terminal 6, which is measured when diagnosing deterioration of the semiconductor module 1. Fig. 5 is a graph showing an example of the voltage waveform of Vee when the semiconductor module 1 is not deteriorated (hereinafter also simply referred to as a healthy state).

[0039] The graph shown in Figure 5 shows how Vee changes over time t when a main current is passed through the semiconductor module 1. The horizontal axis of the graph represents time t. Time t0 is the time when the main current begins to pass through the semiconductor module 1. The vertical axis of the graph represents the value of Vee. V0 is the voltage value when Vee suddenly rises immediately after the main current begins to pass through the semiconductor module 1 at time t0.

[0040] As shown in Figure 5, the value of Vee gradually increases after reaching V0. This increase in voltage value is due to an increase in the resistance value of the wiring 8. The resistance value of the wiring 8 gradually increases as the temperature of the wiring 8 increases after the main current begins to flow through the semiconductor module 1. The main cause of the temperature increase in the wiring 8 is heat conduction from the 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 increase in the wiring 8 saturates.

[0041] 5 is the value of Vee after the transient voltage increase caused by the temperature rise of the wiring 8 has subsided. In other words, V1 is the voltage when the voltage reaches a steady state after the transient voltage increase. Time t1 is the time when Vee reaches V1.

[0042] From the above explanation, the waveform of Vee can be classified and considered from the following first to third viewpoints. The first viewpoint is the time (t0) immediately after the main current starts to flow through the semiconductor module 1. The second viewpoint is the period (between time t0 and time t1) when the value of Vee transiently rises. The third viewpoint is the time (t1) when the transient voltage rise of Vee converges and Vee reaches V1.

[0043] Next, with reference to FIGS. 6 to 8, first to third findings obtained by the inventors of the invention according to the present disclosure through experiments using a semiconductor module 1 simulating a deteriorated state will be described.

[0044] The first finding is the relationship between the deterioration of the semiconductor module 1 and the Vee waveform when only the joint 12 deteriorates. The inventors prepared multiple samples of the semiconductor module 1 simulating a state in which only the joint 12 deteriorates, each with a different degree of deterioration. Then, the Vee waveforms of the samples were measured and compared. As a result, the inventors discovered that when only the joint 12 deteriorates, the Vee voltage value V0 immediately after the main current begins to flow through the semiconductor module 1 changes depending on the degree of deterioration of the joint 12. The inventors also discovered that the transient change in the Vee value progresses in a substantially similar manner regardless of the degree of deterioration of the joint 12.

[0045] 6 is a graph showing an example of the Vee waveform of a semiconductor module 1 in which only the joints 12 have deteriorated. The graph in FIG. 6 shows three waveforms (waveform a1, waveform a2, and waveform a3) superimposed on one another. Waveform a1, shown by a dashed line, represents the waveform when the degree of deterioration of the joints 12 is small. Waveform a2, shown by a dot-dash line, represents the waveform when the degree of deterioration of the joints 12 is medium. Waveform a3, shown by a solid line, represents the waveform when the degree of deterioration of the joints 12 is large.

[0046] 6, the value of V0 increases as the degree of deterioration of the junction 12 increases. This is because the resistance value of the emitter-side parasitic resistance component 14 increases as the degree of deterioration of the junction 12 increases.

[0047] As shown in FIG. 6 , the curve showing the transient change in the Vee value from t0 to t1 has almost the same shape regardless of the degree of deterioration of the joint 12. This can be explained as follows. That is, the increase in the Vee value from t0 to t1 is caused by an increase in the resistance value of the wiring 8. The resistance value of the wiring 8 increases as the temperature of the wiring 8 increases. The main cause of the temperature increase in the wiring 8 is heat conduction from the semiconductor element 2, which generates heat due to the passage of the main current. Even if the joint 12 deteriorates, the saturation temperature of the semiconductor element 2 remains almost unchanged. Furthermore, the progression of the temperature increase of the semiconductor element 2 from t0 to t1 remains almost unchanged due to the deterioration of the joint 12. Therefore, even if the degree of deterioration of the joint 12 changes, the shape of the curve showing the transient change in the Vee value from t0 to t1 remains almost unchanged. That is, as the deterioration of the joint 12 progresses, the value of V0 increases, but the curve showing the subsequent transition becomes similar in shape, and behaves as if the curve has shifted in parallel.

[0048] The second finding is the finding of the relationship between the deterioration of the semiconductor module 1 and the Vee waveform when only the bonding material 11 deteriorates. The inventors prepared multiple samples of the semiconductor module 1 simulating a state in which only the bonding material 11 deteriorates, each sample having a different degree of deterioration. Then, the Vee waveforms of the samples were measured and compared. As a result, the inventors found that when only the bonding material 11 deteriorates, the Vee voltage value V1 after the transient change in the Vee value and the transient voltage rise have converged varies depending on the degree of deterioration of the bonding material 11.

[0049] Fig. 7 is a graph showing an example of the Vee waveform of a semiconductor module 1 in which only the bonding material 11 has deteriorated. The graph in Fig. 7 shows three waveforms (waveform b1, waveform b2, and waveform b3) superimposed on one another. Waveform b1, shown by a dashed line, represents a waveform when the degree of deterioration of the bonding material 11 is small. Waveform b2, shown by a dot-dash line, represents a waveform when the degree of deterioration of the bonding material 11 is medium. Waveform b3, shown by a solid line, represents a waveform when the degree of deterioration of the bonding material 11 is large.

[0050] As shown in FIG. 7 , the slope of the curve showing the transient change in the Vee value from t0 to t1 increases as the degree of deterioration of the bonding material 11 increases. Here, the slope of the curve showing the transient change in the Vee value can also be considered as the amount of change in the Vee value per unit time. Furthermore, the value of V1 increases as the degree of deterioration of the bonding material 11 increases. This can be explained as follows. That is, when the bonding material 11 deteriorates, the value of thermal resistance in the heat dissipation path from the semiconductor element 2 to the conductive member 10 increases, resulting in a higher saturation temperature of the semiconductor element 2. As the saturation temperature of the semiconductor element 2 increases, the saturation temperature of the wiring 8 also increases, resulting in an increase in the value of V1. Furthermore, as the value of V1 increases, the slope of the curve showing the transient change in the Vee value from t0 to t1 increases.

[0051] 7, the value of V0 is the same regardless of the degree of deterioration of the bonding material 11. This is because the temperature of the wiring 8 has not risen at time t0.

[0052] The third finding is the finding of the relationship between the deterioration of the semiconductor module 1 and the Vee waveform when both the bonding material 11 and the bonding portion 12 are deteriorated. The inventors produced multiple samples of the semiconductor module 1 simulating a state in which the bonding material 11 and the bonding portion 12 are deteriorated, each sample having different combinations of the degree of deterioration. Then, the inventors measured Vee for each sample and compared the Vee waveforms for each sample. As a result, the inventors found that the value of V1 may be the same when the combinations of the degree of deterioration of the bonding material 11 and the bonding portion 12 are different.

[0053] Fig. 8 is a graph showing an example of a Vee waveform of a semiconductor module 1 in which the bonding material 11 and the bonding portion 12 have deteriorated. The graph in Fig. 8 shows two waveforms, waveform c1 and waveform c2, superimposed on each other. Waveform c1, shown by a dashed line, represents a waveform when the degree of deterioration of the bonding portion 12 is small and the degree of deterioration of the bonding material 11 is large. Waveform c2, shown by a solid line, represents a waveform when the degree of deterioration of the bonding portion 12 is large and the degree of deterioration of the bonding material 11 is small.

[0054] V1 is a value obtained by adding the increase in Vee caused by the temperature rise of the wiring 8 to V0. In other words, V1 is a value that reflects both the deterioration of the bonding material 11 and the bonding portion 12. As shown in Fig. 8 , the value of V1 when the degree of deterioration of the bonding portion 12 is small and the degree of deterioration of the bonding material 11 is large (waveform c1) may match the value of V1 when the degree of deterioration of the bonding portion 12 is large and the degree of deterioration of the bonding material 11 is small (waveform c2).

[0055] Therefore, for example, when the deterioration of the semiconductor module 1 is detected by whether the value of V1 reaches a preset threshold value as in the conventional method, it is possible to know whether either the bonding material 11 or the bonding portion 12, or both, have deteriorated. However, in a method such as this example in which only the voltage is measured a certain time after the main current is passed through the semiconductor module 1, it is not possible to know to what extent either the bonding material 11 or the bonding portion 12 has deteriorated.

[0056] The findings obtained through the inventors' extensive research have been described above. Next, a method for diagnosing deterioration of the semiconductor module 1 that was discovered based on the first to third findings will be described.

[0057] First, a method for diagnosing the deterioration of the joint 12 will be described. As described in the explanation of the first finding, the value of V0 increases as the degree of deterioration of the joint 12 increases. Also, as described in the explanation of the second finding, the value of V0 does not depend on the degree of deterioration of the joining material 11. Therefore, the deterioration of the joint 12 can be diagnosed based on the measurement results of V0.

[0058] Regarding the deterioration diagnosis of the joint 12 based on the measurement results of V0, specifically, the deterioration of the joint 12 of the semiconductor module 1 to be diagnosed can be diagnosed by comparing V0 (hereinafter referred to as V0_n) of the semiconductor module 1 to be diagnosed with V0 in a healthy state of the semiconductor module 1 (hereinafter referred to as V0_ini).

[0059] The comparison between V0_n and V0_ini may be a comparison based on the difference between V0_n and V0_ini, or a comparison based on the ratio between V0_n and V0_ini.

[0060] Furthermore, by comparing V0_n with a value of V0 (hereinafter referred to as V0_ref) that is set in advance as a reference, rather than V0_ini, it is also possible to diagnose the deterioration of the joint 12. As with the comparison between V0_n and V0_ini, the comparison between V0_n and V0_ref may be based on the difference between V0_n and V0_ref, or on the ratio between V0_n and V0_ref.

[0061] Here, it is desirable to accurately measure V0 in order to accurately diagnose the deterioration of the joint 12. As described above, V0 is the voltage value when Vee suddenly rises immediately after the main current starts to flow through the semiconductor module 1 at time t0 (see FIG. 5). The value of Vee gradually increases as the temperature of the wiring 8 rises.

[0062] Therefore, it is desirable to measure V0 when Vee rises sharply to a certain value and before the temperature of the wiring 8 begins to rise. There are no particular limitations on the method for measuring V0 at such timing, but one example is a method in which a gate drive signal for turning on the semiconductor element 2 is received and the time point at which this gate drive signal is received is used as the reference point. In this method, Vee is measured a predetermined delay time after the time point at which the gate drive signal is received, and this value is used as V0. In other words, the predetermined delay time is appropriately adjusted to measure V0 with high accuracy.

[0063] Another example of a method for adjusting the timing of measuring V0 is to utilize an electrical characteristic that changes the instant the semiconductor element 2 is turned on. Examples of such electrical characteristics include the gate voltage, Vee, or main current. Specifically, for example, the point in time when the gate voltage reaches a predetermined threshold is used as a reference, and Vee is measured a predetermined delay time after that point in time, and the measured value is set as V0.

[0064] Alternatively, Vee may be monitored at a high sampling rate, and a sudden rise in Vee may be detected by differentiating the monitored Vee, and V0, which is the voltage value when Vee suddenly rises, may be measured.

[0065] Next, a method for diagnosing the deterioration of the bonding material 11 will be described. As described in the explanation of the third finding, V1 is a value that reflects the deterioration of both the bonding material 11 and the bonding portion 12. As described above, the deterioration of the bonding portion 12 can be diagnosed based on the measurement results of V0. Therefore, for V1, the deterioration of the bonding material 11 can be diagnosed by excluding the contribution of the deterioration of the bonding portion 12 obtained based on the measurement results of V0. In other words, the deterioration of the bonding material 11 can be diagnosed based on a comparison between V0 and V1.

[0066] Degradation diagnosis of the bonding material 11 based on a comparison between V0 and V1 will be described with reference to FIG. 9 . FIG. 9 is a graph showing an example of the Vee waveform of a semiconductor module 1 that has experienced a certain degree of degradation. The graph in FIG. 9 displays two waveforms, waveform d1 and waveform d2, superimposed on each other. The waveform d1, shown by a dashed line, represents the Vee waveform of the semiconductor module 1 in a healthy state. The waveform d2, shown by a solid line, represents the Vee waveform of the semiconductor module 1 in which degradation has occurred in the bonding material 11 and the bonding portion 12. Furthermore, V1_n shown in FIG. 9 represents V1 of the semiconductor module 1 to be diagnosed. V1_ini shown in FIG. 9 represents V1 when the semiconductor module 1 is in a healthy state.

[0067] First, by comparing V1_n with V1_ini, it is possible to grasp the deterioration of the semiconductor module 1 due to the deterioration of the bonding material 11 and the bonding portion 12. Then, by subtracting the contribution of the deterioration of the bonding portion 12 obtained by comparing V0_n with V0_ini from the comparison result, it is possible to diagnose the deterioration of the bonding material 11.

[0068] More specifically, by comparing the difference between V1_n and V1_ini with the difference between V0_n and V0_ini, it is possible to diagnose the deterioration of the bonding material 11. Furthermore, by comparing the ratio between V1_n and V1_ini with the ratio between V0_n and V0_ini, it is also possible to diagnose the deterioration of the bonding material 11. Note that the comparison between the difference between V1_n and V1_ini and the difference between V0_n and V0_ini, and the comparison between the ratio between V1_n and V1_ini and the ratio between V0_n and V0_ini may be a comparison based on difference or a comparison based on division.

[0069] Furthermore, the deterioration of the bonding material 11 may be diagnosed by comparing the difference between V1_ini and V0_ini with the difference between V1_n and V0_n, or by comparing the ratio between V1_ini and V0_ini with the ratio between V1_n and V0_n. In this case, the comparison method may be a difference or a division.

[0070] Furthermore, instead of V1_ini, deterioration of the bonding material 11 may be diagnosed by calculation using V1_ref, which is a value of V1 set in advance as a reference. For example, deterioration of the bonding material 11 may be diagnosed by comparing the difference between V1_ref and V0_ref with the difference between V1_n and V0_n, or by comparing the ratio between V1_ref and V0_ref with the ratio between V1_n and V0_n. In this case, the comparison method may be difference or division.

[0071] Here, the timing for measuring V1 will be described. V1 can be measured by setting t1, which is a time delayed from t0 by a time sufficient for the temperature of the wiring 8 to saturate and the transient increase in Vee to converge. Alternatively, Vee can be monitored and differentiated to detect that the transient voltage increase in Vee has converged, and V1 can be measured at the timing of this convergence.

[0072] The method for diagnosing deterioration of the semiconductor module 1 that was discovered based on the findings obtained through the inventors' extensive research has been described above.

[0073] [1-2. Operation] Next, the operation of degradation diagnosis device 100 will be described.

[0074] First, with reference to FIGS. 1 and 2, the operation of the deterioration diagnostic device 100 for diagnosing the deterioration of the joint 12 (see FIGS. 3 and 4) will be described.

[0075] When the semiconductor element 2 is turned on and the main current starts to flow through the semiconductor module 1, the voltage measurement unit 101 shown in Figure 1 measures Vee (V0_n) at a first time (t0) immediately after the main current starts to flow through the semiconductor module 1.

[0076] 1, the voltage measurement unit 101 outputs V0_n to the diagnostic processing unit 102. Then, as shown in FIG. 2, the value of V0_n is input to a first calculation unit 103 provided in the diagnostic processing unit 102 and is recorded in a first storage unit 106 provided in the diagnostic processing unit 102.

[0077] The first storage unit 106 stores the value of V0 (V0_ini) when the semiconductor module 1 is in a healthy state.

[0078] The first calculation unit 103 reads out V0_ini from the first storage unit 106, compares V0_n with V0_ini, and diagnoses the deterioration state of the joint 12. The contents of the diagnosis of the deterioration state of the joint 12 by the first calculation unit 103 are not particularly limited. For example, the first calculation unit 103 may output the difference value between V0_n and V0_ini as information indicating the diagnosis result of the deterioration state of the joint 12. As another example, the first calculation unit 103 may determine whether the difference value between V0_n and V0_ini exceeds a predetermined value set in advance, and output the determination result.

[0079] The value recorded in the first storage unit 106 and compared with the value of V0_n in the first calculation unit 103 is not limited to V0_ini. For example, it may be a value (V0_ref) set in advance as a reference.

[0080] Next, with reference to FIGS. 1 and 2, the operation of the deterioration diagnostic device 100 for diagnosing the deterioration of the bonding material 11 (see FIG. 3) will be described.

[0081] 1 measures Vee (V1_n) at a second time when the temperature of the wiring 8 has saturated and the transient increase in Vee has converged. At the second time, the semiconductor element 2 is in an on state and a main current is flowing through the semiconductor module 1.

[0082] 1, the voltage measurement unit 101 outputs V1_n to the diagnostic processing unit 102. Then, as shown in FIG. 2, the value of V1_n is input to a second calculation unit 104 included in the diagnostic processing unit 102.

[0083] The second calculation unit 104 reads V0_n from the first storage unit 106, and performs a comparison calculation between V1_n and V0_n to calculate a comparison calculation value V3_n. The comparison calculation method by the second calculation unit 104 is, for example, the difference between V1_n and V0_n or the ratio between V1_n and V0_n. The second calculation unit 104 outputs the calculated comparison calculation value V3_n to the third calculation unit 105.

[0084] The comparison calculation value V3_ini calculated by the second calculation unit 104 through a comparison calculation between the value of V1 (V1_ini) and the value of V0 (V0_ini) when the semiconductor module 1 is in a healthy state is recorded in the second storage unit 107.

[0085] The third calculation unit 105 reads out V3_ini from the second storage unit 107, and compares V3_n with V3_ini to diagnose the deterioration state of the bonding material 11. Note that the V3_n and V3_ini compared in the third calculation unit 105 use values ​​calculated by the same comparison calculation method. That is, for example, when V3_n is a value obtained by dividing V1_n by V0_n, the value obtained by dividing V1_ini by V0_ini is used as V3_ini.

[0086] There is no particular limitation on the content of the diagnosis of the deterioration state of the bonding material 11 by the third calculation unit 105. For example, the third calculation unit 105 may output the value of the difference between V3_n and V3_ini as information indicating the diagnosis result of the deterioration state of the bonding material 11. As another example, the third calculation unit 105 may determine whether the value of the difference between V3_n and V3_ini exceeds a predetermined value set in advance, and output the determination result.

[0087] Furthermore, the value recorded in the second storage unit 107 and compared with the value of V3_n in the third calculation unit 105 is not limited to V3_ini. For example, it may be a value (V3_ref) set in advance as a reference.

[0088] [1-3. Effects, etc.] As described above, in the present embodiment, the degradation diagnosis device 100 diagnoses degradation of the semiconductor module 1 including the semiconductor element 2 having the collector electrode 3 a as a first main electrode and the emitter electrode 5 a as a second main electrode, and includes: a voltage measurement unit 101 that measures the voltage between the emitter main terminal 5 as a second main terminal electrically connected to the emitter electrode 5 a via wiring 8, and the emitter reference terminal 6 that is a reference terminal that detects the potential of the emitter electrode 5 a; and a diagnostic processing unit 102 that diagnoses degradation of the semiconductor module 1 based on the measurement results of the voltage measurement unit 101. The voltage measurement unit 101 measures a first voltage at a first time immediately after the flow of a main current to the semiconductor module 1 starts, and a second voltage at a second time after the convergence of the transient rise in voltage between the emitter main terminal 5 and the emitter reference terminal 6, and the diagnostic processing unit 102 diagnoses degradation of the bonding material 11 bonded to the collector electrode 3 a based on a comparison between the first voltage and the second voltage.

[0089] This allows for individual diagnosis of the deterioration of the bonding material 11 when diagnosing the deterioration of the semiconductor module 1. Since the deterioration of the bonding material 11 can be individually diagnosed, the life of the semiconductor module 1 can be more appropriately estimated compared to when individual diagnosis is not possible, and more appropriate maintenance measures for the semiconductor module 1 can be taken.

[0090] Furthermore, the diagnostic processing unit 102 is configured to diagnose degradation of the semiconductor module 1 based on the measurement results of the voltage measurement unit 101, and there is no need to measure the temperature of the semiconductor element 2. Therefore, there is no need to provide a mechanism for measuring the temperature of the semiconductor element 2, and the degradation diagnosis device 100 and the semiconductor device 200 can be made smaller than when a mechanism for measuring the temperature of the semiconductor element 2 is provided.

[0091] Furthermore, the second voltage can be measured more stably when the transient voltage increase of Vee has converged and the steady state has been reached, rather than during the transient increase of Vee. Therefore, the deterioration diagnosis device 100 of the present embodiment can accurately diagnose the deterioration of the bonding material 11.

[0092] Furthermore, in this embodiment, degradation diagnosis device 100 can employ a configuration in which diagnostic processing unit 102 diagnoses degradation of joint 12 between wiring 8 and emitter electrode 5 a based on the value of the first voltage. That is, in the degradation diagnosis of semiconductor module 1, degradation of bonding material 11 and degradation of joint 12 can be diagnosed separately.

[0093] Furthermore, in this embodiment, the diagnostic processing unit 102 may be configured to 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, one aspect of the deterioration diagnosis of the bonding material 11 based on a comparison between the first voltage and the second voltage is the deterioration diagnosis of the bonding material 11 based on the first voltage and the second voltage, and a predetermined reference value. In this case, the predetermined reference value may be a value set based on the first voltage (V0_ini) and the second voltage (V1_ini) when the semiconductor module 1 is in a healthy state.

[0094] Furthermore, in this embodiment, the diagnostic processing unit 102 may be configured to diagnose deterioration of the bonding material 11 based on the result of comparing the first voltage (V0_n) with a predetermined first reference value and the result of comparing the second voltage (V1_n) with a predetermined second reference value. That is, as another aspect of the deterioration diagnosis of the bonding material 11 based on the comparison of the first voltage with the second voltage, there may be mentioned the deterioration diagnosis of the bonding material 11 based on the result of comparing the first voltage with a predetermined first reference value and the result of comparing the second voltage with a predetermined second reference value. In this case, the predetermined first reference value may be a value set based on the first voltage (V0_ini) when the semiconductor module 1 is in a healthy state. Furthermore, the predetermined second reference value may be a value set based on the second voltage (V1_ini) when the semiconductor module 1 is in a healthy state.

[0095] [1-4. Modifications] A modification of the first embodiment will be described with reference to FIGS.

[0096] In the degradation diagnosis device 100 according to the first embodiment, the voltage measurement unit 101 is configured to measure 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 shown in Fig. 10, a configuration may be adopted in which 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.

[0097] 10 is a diagram showing a schematic configuration of a semiconductor device 200 including a degradation diagnosis device 100 according to a modification of the first embodiment. As shown in Fig. 10, the collector main terminal 3 and the emitter main terminal 5 are connected to a voltage measurement unit 101. The voltage measurement unit 101 measures a 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 the voltage Vce to a diagnosis processing unit 102.

[0098] In the description of the first embodiment, the description of the configuration for measuring Vee is valid even if Vee is replaced with Vce.

[0099] Therefore, in this embodiment, the degradation diagnosis device 100 diagnoses degradation of a semiconductor module 1 including a semiconductor element 2 having a collector electrode 3 a as a first main electrode and an emitter electrode 5 a as a second main electrode, and includes: a voltage measurement unit 101 that measures the voltage between the collector main terminal 3 as a first main terminal electrically connected to the collector electrode 3 a and the emitter main terminal 5 as a second main terminal electrically connected to the emitter electrode 5 a via wiring 8; and a diagnostic processing unit 102 that diagnoses degradation of the semiconductor module 1 based on the measurement results of the voltage measurement unit 101, in which the voltage measurement unit 101 measures a first voltage at a first time immediately after the flow of a main current to the semiconductor module 1 starts and a second voltage at a second time after the convergence of the transient rise in voltage between the collector main terminal 3 and the emitter main terminal 5, and the diagnostic processing unit 102 diagnoses degradation of the bonding material 11 bonded to the collector electrode 3 a based on a comparison between the first voltage and the second voltage.

[0100] When a configuration is adopted in which voltage measurement unit 101 measures voltage Vce, degradation diagnosis device 100 can be applied to a semiconductor module 1 that does not have an emitter reference terminal 6, as shown in FIG. 11 .

[0101] 11 is a diagram showing another example of the configuration of a semiconductor device 200 including a degradation diagnosis device 100 according to a modification of embodiment 1. As shown in FIG. 11 , a semiconductor module 1 included in the semiconductor device 200 does not include an emitter reference terminal 6.

[0102] Therefore, in this embodiment, the degradation diagnosis device 100 diagnoses degradation of the semiconductor module 1 including the semiconductor element 2 having the collector electrode 3 a, which is a first main electrode, and the emitter electrode 5 a, which is a second main electrode, and includes a voltage measurement unit 101 that measures the voltage between the collector main terminal 3, which is a first main terminal electrically connected to the collector electrode 3 a, and the emitter main terminal 5, which is a second main terminal electrically connected to the emitter electrode 5 a via a wiring 8, or the voltage between the emitter reference terminal 6, which is a reference terminal for detecting the potential of the emitter electrode 5 a, and the emitter main terminal 5. and a diagnostic processing unit 102 that diagnoses deterioration of the semiconductor module 1 based on the measurement results of the voltage measurement unit 101, wherein the voltage measurement unit 101 measures a first voltage at a first time immediately after the flow of main current to the semiconductor module 1 starts and a second voltage at a second time after the convergence of a transient rise in 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, and the diagnostic processing unit 102 can be configured to diagnose deterioration of the bonding material 11 bonded to the collector electrode 3 a based on a comparison between the first voltage and the second voltage.

[0103] Second Embodiment With reference to Figures 12 to 14, a second embodiment will be described, focusing mainly on the differences from the first embodiment.

[0104] [2-1. Configuration] Fig. 12 is a diagram showing a schematic configuration of a semiconductor device 210 including a degradation diagnosis device 110 according to the second embodiment. Fig. 13 is a diagram showing a schematic configuration of a diagnosis processing unit 112 included in the degradation diagnosis device 110 according to the second embodiment. Fig. 14 is a graph for explaining a method of diagnosing degradation of a semiconductor module 1 according to the second embodiment.

[0105] 12 and 13, the configuration of degradation diagnosis device 110 of embodiment 2 is similar to the configuration of degradation diagnosis device 100 of embodiment 1, but the functions and operations of some components are different. The functions and operations that differ from those of degradation diagnosis device 100 of embodiment 1 will be explained in the explanation of the operation that will be given later.

[0106] A method of diagnosing deterioration of the semiconductor module 1 in the second embodiment will be described with reference to Fig. 14. Similar to Fig. 9, Fig. 14 shows an example of the Vee waveform of the semiconductor module 1 in which some degree of deterioration has occurred.

[0107] The graph in Figure 14 displays two waveforms, waveform e1 and waveform e2, superimposed on each other. Waveform e1, shown by a dashed line, represents the waveform of Vee of the semiconductor module 1 in a healthy state. Waveform e2, shown by a solid line, represents the waveform of Vee of the semiconductor module 1 in which deterioration of the bonding material 11 and the bonding portions 12 has occurred. For waveform e1, the measured value of Vee at time t0 is V0_ini, the measured value of Vee at time ta is Va_ini, the measured value of Vee at time tb is Vb_ini, and the measured value of Vee at time t1 is V1_ini. For waveform e2, the measured value of Vee at time t0 is V0_n, the measured value of Vee at time ta is Va_n, the measured value of Vee at time tb is Vb_n, and the measured value of Vee at time t1 is V1_n.

[0108] As described in the explanation of the second finding in the explanation of the first embodiment, the progression of the voltage increase (the slope of the voltage waveform) from when Vee reaches V0 until it reaches V1 varies depending on the degree of deterioration of the bonding material 11. Therefore, it is possible to diagnose the deterioration of the bonding material 11 based on a comparison of Va and Vb shown in FIG. 14 . Va is the value of Vee measured at ta after t0. ta is an arbitrarily determined time in the period from t0 to t1. Vb is the value of Vee measured at tb after ta. tb is an arbitrarily determined time in the period from t0 to t1, which is later than ta.

[0109] Regarding the deterioration diagnosis of the bonding material 11 based on the comparison between Va and Vb, specifically, for example, the difference between Vb_n and Va_n and the difference between Vb_ini and Va_ini can be compared to diagnose the degree of deterioration of the bonding material 11. However, the method of diagnosing the deterioration of the bonding material 11 based on the comparison between Va and Vb is not limited to this, and any method based on an index that reflects the slope of the waveform e2 from ta to tb may be used.

[0110] Furthermore, it is not essential to use the waveform e1 in the healthy state as a standard for diagnosis, and any standard may be used for diagnosis. For example, the degree of deterioration of the bonding material 11 may be diagnosed based on whether the difference between Vb_n and Va_n exceeds a preset threshold value.

[0111] Furthermore, it is not essential that both Va and Vb be voltage values ​​measured during the period when Vee is transiently rising. Of Va and Vb, Va may be the voltage value (V0) when Vee suddenly rises immediately after the main current begins to flow through the semiconductor module 1, and Vb may be the voltage value measured during the period when Vee is transiently rising. Also, of Va and Vb, Va may be the voltage value measured during the period when Vee is transiently rising, and Vb may be the voltage value (V1) measured after the transient voltage rise in Vee has subsided.

[0112] [2-2. Operation] Next, the operation of degradation diagnosis device 110 according to the second embodiment will be described.

[0113] 12 and 13, the operation of diagnosing the deterioration of the bonding material 11 (see FIG. 3) in the deterioration diagnosis device 110 of embodiment 2 will be described. Note that the operation of diagnosing the deterioration of the bonding portion 12 is the same as in embodiment 1, and therefore the description thereof will be omitted.

[0114] The voltage measurement unit 111 shown in FIG. 12 measures Vee (Va_n) at a second time ta, which is after the first time t0, and Vee (Vb_n) at a third time tb, which is after the second time ta. At the third time tb, the semiconductor element 2 is in an on state, and a main current is flowing through the semiconductor module 1. Here, as shown in FIG. 12, a case will be described in which the voltage measurement unit 111 measures Va and Vb during a period in which the temperature of the wiring 8 transiently rises and Vee transiently rises. However, Va may be a voltage value (V0) measured immediately after the main current begins to flow through the semiconductor module 1. Furthermore, Vb may be a voltage value (V1) measured after the transient voltage rise of Vee has subsided.

[0115] 12 , the voltage measurement unit 111 outputs Va_n and Vb_n to the diagnostic processing unit 112. Then, as shown in FIG. 13 , the value of Va_n is input to and recorded in a first storage unit 116 provided in the diagnostic processing unit 112. The value of Vb_n is input to a second calculation unit 114 provided in the diagnostic processing unit 112.

[0116] The second calculation unit 114 reads Va_n from the first storage unit 116, and performs a comparison calculation between Vb_n and Va_n to calculate a comparison calculation value V4_n. The comparison calculation method used by the second calculation unit 114 is, for example, the difference between Vb_n and Va_n or the ratio between Vb_n and Va_n. The second calculation unit 114 outputs the calculated comparison calculation value V4_n to the third calculation unit 115.

[0117] The comparison calculation value V4_ini calculated by the second calculation unit 114 through the comparison calculation between the value of Vb (Vb_ini) and the value of Va (Va_ini) when the semiconductor module 1 is in a healthy state is recorded in the second storage unit 117.

[0118] The third calculation unit 115 reads out V4_ini from the second storage unit 117, and compares V4_n with V4_ini to diagnose the deterioration state of the bonding material 11. Note that the V4_n and V4_ini compared in the third calculation unit 115 use values ​​calculated by the same comparison calculation method. That is, for example, if V4_n is a value obtained by dividing Vb_n by Va_n, the value obtained by dividing Vb_ini by Va_ini is used as V4_ini.

[0119] There is no particular limitation on the content of the diagnosis of the deterioration state of the bonding material 11 by the third calculation unit 115. For example, the third calculation unit 115 may output the value of the difference between V4_n and V4_ini as information indicating the diagnosis result of the deterioration state of the bonding material 11. As another example, the third calculation unit 115 may determine whether the value of the difference between V4_n and V4_ini exceeds a predetermined value set in advance, and output the determination result.

[0120] Furthermore, the value recorded in the second storage unit 117 and compared with the value of V4_n in the third calculation unit 115 is not limited to V4_ini. For example, it may be a value (V4_ref) set in advance as a reference.

[0121] [2-3. Effects, etc.] As described above, in this embodiment, the voltage measurement unit 111 measures a first voltage at a first time during a period in which Vee transiently increases after the main current starts flowing through the semiconductor module 1, and a second voltage at a second time after the first time, and the diagnosis processing unit 112 diagnoses deterioration of the bonding material 11 bonded to the collector electrode 3 a based on a comparison between the first voltage and the second voltage.

[0122] As a result, similarly to the first embodiment, the deterioration of the bonding material 11 can be individually diagnosed in the deterioration diagnosis of the semiconductor module 1 .

[0123] Furthermore, as in the first embodiment, there is no need to provide a mechanism for measuring the temperature of the semiconductor element 2, and the degradation diagnosis device 110 and the semiconductor device 210 can be made smaller than when a mechanism for measuring the temperature of the semiconductor element 2 is provided.

[0124] When diagnosing the deterioration of the bonding material 11 based on the slope of the transiently rising voltage waveform, a larger slope of the voltage waveform allows for more accurate diagnosis of the deterioration of the bonding material 11. Therefore, it is preferable that the first time point and the second time point be close to the time point when the main current starts to flow through the semiconductor module 1.

[0125] In the present embodiment, the first time point may be the time point immediately after the start of supplying the main current to the semiconductor module 1. In this case, a configuration can be adopted in which the diagnostic processing unit 112 diagnoses the deterioration of the joint 12 between the wiring 8 and the emitter electrode 5 a based on the value of the first voltage.

[0126] In this embodiment, the second time may be a time after the convergence of the transient increase in Vee.

[0127] In this embodiment, when the first time is the time immediately after the start of supplying main current to the semiconductor module 1 and the second time is a time within the period in which Vee transiently rises, the voltage measurement unit 111 further measures a third voltage at a third time after the second time, and the diagnostic processing unit 112 diagnoses deterioration of the bonding material 11 based on a comparison between the second voltage and the third voltage, and diagnoses deterioration of the bonding portion 12 between the wiring 8 and the emitter electrode 5 a based on the value of the first voltage.

[0128] In addition, in this embodiment, the diagnostic processing unit 112 may be configured to diagnose the deterioration of the bonding material 11 based on the second voltage (Va_n), the third voltage (Vb_n), and a predetermined reference value. That is, one aspect of the deterioration diagnosis of the bonding material 11 based on a comparison between the second voltage and the third voltage is the deterioration diagnosis of the bonding material 11 based on the second voltage and the third voltage, and a predetermined reference value. In this case, the predetermined reference value may be a value set based on the second voltage (Va_ini) and the third voltage (Vb_ini) when the semiconductor module 1 is in a healthy state.

[0129] Furthermore, in this embodiment, the diagnostic processing unit 112 may be configured to diagnose deterioration of the bonding material 11 based on the result of comparing the second voltage (Va_n) with a predetermined first reference value and the result of comparing the third voltage (Vb_n) with a predetermined second reference value. That is, as another aspect of the deterioration diagnosis of the bonding material 11 based on the comparison of the second voltage with the third voltage, there may be mentioned the deterioration diagnosis of the bonding material 11 based on the result of comparing the second voltage with the predetermined first reference value and the result of comparing the third voltage with the predetermined second reference value. In this case, the predetermined first reference value may be a value set based on the second voltage (Va_ini) when the semiconductor module 1 is in a healthy state. Furthermore, the predetermined second reference value may be a value set based on the third voltage (Vb_ini) when the semiconductor module 1 is in a healthy state.

[0130] In this embodiment, if the first time corresponds to the time immediately after the start of supply of the main current to the semiconductor module 1, the second time corresponds to the first time, the second voltage corresponds to the first voltage, the third time corresponds to the second time, and the third voltage corresponds to the second voltage, the diagnostic processing unit 112 diagnoses deterioration of the bonding material 11 bonded to the collector electrode 3 a based on a comparison between the first voltage and the second voltage, and the diagnostic processing unit 112 diagnoses deterioration of the bonding portion 12 between the wiring 8 and the emitter electrode 5 a based on the voltage value measured by the voltage measurement unit 111 at the time immediately after the start of supply of the main current to the semiconductor module 1. In this case, the first time is a time after the time immediately after the start of supply of the main current to the semiconductor module 1. The second time is a time within a period during which the voltage between the collector main terminal 3 serving as the first main terminal and the emitter main terminal 5 serving as the second main terminal or the voltage between the emitter reference terminal 6 serving as the reference terminal and the emitter main terminal 5 serving as the second main terminal transiently rises.

[0131] [2-4. Modifications] In the second embodiment, it is possible to employ the same modification as in the first embodiment. That is, in the second embodiment as well, it is possible to employ a configuration in which the voltage measurement 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.

[0132] Furthermore, in the second embodiment as well, if a configuration is adopted in which the voltage measurement unit 111 measures the voltage Vce, the degradation diagnosis device 110 can be applied to a semiconductor module 1 that does not have an emitter reference terminal 6.

[0133] Therefore, in this embodiment, the voltage measurement unit 111 measures a first voltage at a first time during the period when the main current starts to flow to the semiconductor module 1 and Vce transiently rises, and a second voltage at a second time after the first time, and the diagnostic processing unit 112 can be configured to diagnose deterioration of the bonding material 11 bonded to the collector electrode 3a based on a comparison between the first voltage and the second voltage.

[0134] Third Embodiment With reference to Figures 15 to 17, a third embodiment will be described, focusing mainly on the differences from the first embodiment.

[0135] [3-1. Configuration] Fig. 15 is a diagram showing a schematic configuration of a semiconductor device 220 including a degradation diagnosis device 120 according to the third embodiment. Fig. 16 is a diagram showing a schematic configuration of a diagnosis processing unit 122 included in the degradation diagnosis device 120 according to the third embodiment. Fig. 17 is a graph for explaining a method of diagnosing degradation of a semiconductor module 1 according to the third embodiment.

[0136] 15 and 16, the configuration of degradation diagnosis device 120 of embodiment 3 differs from the configuration of degradation diagnosis device 100 of embodiment 1 in that diagnosis processing unit 122 does not include a second storage unit. Furthermore, the functions and operations of some components of degradation diagnosis device 120 of embodiment 3 differ from those of degradation diagnosis device 100 of embodiment 1. The functions and operations that differ from those of degradation diagnosis device 100 of embodiment 1 will be explained in the explanation of operation that will be given later.

[0137] A method for diagnosing deterioration of a semiconductor module 1 in the third embodiment will be described with reference to Fig. 17. Fig. 17 shows an example of the waveform of Vee-V0 (a value obtained by subtracting V0 from Vee) of a semiconductor module 1 that has deteriorated to a certain extent.

[0138] 17 shows two waveforms, waveform f1 and waveform f2, superimposed on each other. Waveform f1, shown by a dashed line, represents the Vee-V0 waveform of a healthy semiconductor module 1. Waveform f2, shown by a solid line, represents the Vee-V0 waveform of a semiconductor module 1 in which deterioration of the bonding material 11 and the bonding portion 12 has occurred.

[0139] For both waveform f1 and waveform f2, the Vee measured at time t0 is V0, and therefore the value on the vertical axis at t0 is 0. The value k shown on the vertical axis of the graph is a reference value set in advance for diagnosing the deterioration of the bonding material 11. The value of k is set arbitrarily so that the deterioration of the bonding material 11 can be appropriately diagnosed. Here, as an example, a case is shown in which k is the value (V1-V0) obtained by subtracting V0 from V1 of the semiconductor module 1 in a healthy state.

[0140] For waveform f1, the value of Vee-V0 is k at time t1 when V1 is measured. In other words, for waveform f1, the value of Vee-V0 becomes k at time t1. For waveform f2, the value of Vee-V0 becomes k at time tc.

[0141] 17, as the deterioration of the bonding material 11 progresses, the slope of the waveform of Vee-V0 that rises after t0 becomes larger, and the time at which Vee-V0 becomes k approaches t0. Therefore, it is possible to diagnose the deterioration of the bonding material 11 based on a comparison between tc and t0 shown in FIG.

[0142] Regarding the deterioration diagnosis of the bonding material 11 based on the comparison between tc and t0, specifically, for example, the degree of deterioration of the bonding material 11 can be diagnosed based on the difference between tc and t0.

[0143] 17, the vertical axis is Vee-V0 in order to remove the influence of deterioration of the joint 12 from the Vee obtained by measurement. The method of removing the influence of deterioration of the joint 12 from the Vee obtained by measurement is not limited to subtracting Vee by V0. For example, the influence of deterioration of the joint 12 may be removed from the Vee obtained by measurement by dividing Vee by V0.

[0144] [3-2. Operation] Next, the operation of degradation diagnosis device 120 according to the third embodiment will be described.

[0145] 15 and 16, the operation of diagnosing the deterioration of the bonding material 11 (see FIG. 3) in the deterioration diagnosis device 120 of embodiment 3 will be described. Note that the operation of diagnosing the deterioration of the bonding portion 12 is the same as in embodiment 1, and therefore the description thereof will be omitted.

[0146] The voltage measurement unit 121 shown in FIG. 15 measures Vee at a predetermined sampling rate after the first time t0, and outputs the measured Vee value to the diagnosis processing unit 122.

[0147] 16 , the value of the first voltage V0_n measured at the first time t0 is input to the first storage unit 126 included in the diagnostic processing unit 122 and recorded together with information about the first time t0. In addition, the value of Vee measured after the first time t0 is input to the second calculation unit 124.

[0148] The second calculation unit 124 reads and stores the value of V0_n from the first storage unit 126, and performs a comparison operation between the value of Vee and V0_n each time the value of Vee is input from the voltage measurement unit 121. The comparison operation between Vee and V0_n in the second calculation unit 124 is, for example, a difference or division. The second calculation unit 124 outputs information about a second time tc when the calculated comparison operation value reaches a predetermined reference value k to the third calculation unit 125. Here, the second time tc can also be said to be the time when the voltage measurement unit 121 measures a second voltage Vk, the result of which is compared with the first voltage V0_n and is equal to or greater than the predetermined reference value k.

[0149] The third calculation unit 125 reads information about 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 contents of the diagnosis of the deterioration state of the bonding material 11 by the third calculation unit 125 are not particularly limited. For example, the third calculation unit 125 may output the value of the difference between the first time t0 and the second time tc as information indicating the diagnosis result of the deterioration state of the bonding material 11. As another example, the third calculation unit 125 may determine whether the length of the time difference between the first time t0 and the second time tc is shorter than a predetermined length of time, and output the determination result.

[0150] [3-3. Effects, etc.] As described above, in this embodiment, the voltage measurement unit 121 measures the voltage from the first time immediately after the start of supplying the main current to the semiconductor module 1, and the diagnosis processing unit 122 diagnoses deterioration of the bonding material 11 bonded to the collector electrode 3 a based on a comparison between the first time and the second time at which the voltage measurement unit 121 measures a voltage whose comparison with the first voltage is equal to or greater than a predetermined reference value.

[0151] As a result, similarly to the first embodiment, the deterioration of the bonding material 11 can be individually diagnosed in the deterioration diagnosis of the semiconductor module 1 .

[0152] Furthermore, as in the first embodiment, there is no need to provide a mechanism for measuring the temperature of the semiconductor element 2, and the degradation diagnosis device 120 and the semiconductor device 220 can be made smaller than when a mechanism for measuring the temperature of the semiconductor element 2 is provided.

[0153] Furthermore, the magnitude of change in the slope of the Vee waveform as deterioration of the bonding material 11 progresses is large in the early stages 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 tc in this embodiment also changes significantly. Therefore, the deterioration diagnosis device 120 of this embodiment can accurately diagnose early-stage deterioration of the bonding material 11.

[0154] Furthermore, the reference value k that is set in advance to diagnose the deterioration of the bonding material 11 can be a value calculated based on a comparison between V0 (V0_ini) and V1 (V1_ini) in a 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.

[0155] [3-4. Modifications] In the third embodiment, it is possible to employ the same modification as in the first embodiment. That is, in the third embodiment as well, it is possible to employ a configuration in which the voltage measurement 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.

[0156] Furthermore, in embodiment 3 as well, if a configuration is adopted in which the voltage measurement unit 121 measures the voltage Vce, the degradation diagnosis device 120 can be applied to a semiconductor module 1 that does not have an emitter reference terminal 6.

[0157] The third embodiment has been described above. Finally, with reference to Fig. 18, examples of the hardware configuration of the diagnostic processing unit 102 according to the first embodiment, the diagnostic processing unit 112 according to the second embodiment, and the diagnostic processing unit 122 according to the third embodiment will be described. Note that the hardware configuration example of the diagnostic processing unit 102 according to the first embodiment will be described below as a representative. The hardware configuration examples of the diagnostic processing unit 112 according to the second embodiment and the diagnostic processing unit 122 according to the third embodiment are similar to the hardware configuration example of the diagnostic processing unit 102 according to the first embodiment.

[0158] 18 is a diagram illustrating an example of the hardware configuration of the diagnostic processing unit 102. As illustrated in Fig. 18, the diagnostic processing unit 102 includes a processor 102a and a storage device 102b. For example, degradation diagnosis of the semiconductor module 1 based on the measurement results of the voltage measurement unit 101 is realized by the processor 102a and the storage device 102b.

[0159] The processor 102a is a device that executes programs stored in the memory device 102b. The processor 102a is also called a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, a processor, or a DSP. The processor 102a may include the memory device 102b.

[0160] The functions of the diagnostic processing unit 102 are realized by software, firmware, or a combination of software and firmware. The software and firmware are written as programs and stored in the storage device 102b. The processor 102a realizes the functions of the diagnostic processing unit 102 by reading and executing the programs stored in the storage device 102b.

[0161] Here, the storage device 102b may be a non-volatile or volatile semiconductor memory such as RAM, ROM, flash memory, EPROM, or EEPROM, a magnetic disk, a flexible disk, an optical disk, a compact disk, a minidisk, or a DVD. RAM is an abbreviation for Random Access Memory. ROM is an abbreviation for Read Only Memory. EPROM is an abbreviation for Erasable Programmable Read Only Memory. EEPROM is an abbreviation for Electrically Erasable Programmable Read-Only Memory.

[0162] The processor 102a may also be dedicated hardware. In this case, the processor 102a may be, for example, a single circuit, a composite circuit, a programmed processor, or a parallel programmed processor. The processor 102a may also be an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array). The processor 102a may also be a combination of these.

[0163] Furthermore, each of the multiple functions of the diagnostic processing unit 102 may be realized by a separate diagnostic processing unit, or multiple functions may be realized together by a single diagnostic processing unit.

[0164] Furthermore, some of the functions of the diagnostic processing unit 102 may be realized by dedicated hardware, and some by software or firmware. In this way, the diagnostic processing unit 102 can realize each of the above-described functions by hardware, software, firmware, or a combination of these.

[0165] The first to third embodiments of the present disclosure have been described above. The present disclosure is not limited to the above examples, and appropriate design changes can be made within the scope of the configuration of the present disclosure. For example, it is possible to modify, add, or omit at least one configuration element in the present disclosure, or to extract at least one component element and combine it with a component element of another embodiment.

[0166] REFERENCE SIGNS LIST 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 member 11 Bonding material 12 Bonding portion 13 Collector side parasitic resistance component 14 Emitter side parasitic resistance component 100, 110, 120 Degradation diagnosis device 101, 111, 121 Voltage measurement unit 102, 112, 122 Diagnosis processing unit 102a Processor 102b Storage device 103, 113, 123 First calculation unit 104, 114, 124 Second calculation unit 105, 115, 125 Third arithmetic unit 106, 116, 126 First memory unit 107, 117 Second memory unit 200, 210, 220 Semiconductor device

Claims

1. A degradation diagnosis device for diagnosing degradation of a semiconductor module including a semiconductor element having a first main electrode and a second main electrode, comprising: a voltage measurement unit that measures a 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 a voltage between the second main terminal and a reference terminal that detects the potential of the second main electrode; and a diagnostic processing unit that diagnoses degradation of the semiconductor module based on the measurement results of the voltage measurement unit, wherein the voltage measurement unit measures a first voltage at a first time during a period in which a main current starts to flow through 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 transiently rises, and a second voltage at a second time after the first time, and the diagnostic processing unit diagnoses degradation of a bonding material bonded to the first main electrode based on a comparison of the first voltage and the second voltage.

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

3. The deterioration diagnosis device described in claim 1, wherein the diagnostic processing unit diagnoses deterioration of the joining material based on the result of comparing the first voltage with a predetermined first reference value and the result of comparing the second voltage with a predetermined second reference value.

4. A degradation diagnosis device according to any one of claims 1 to 3, wherein the first time is the time immediately after the main current starts to flow through the semiconductor module.

5. A degradation diagnosis device according to any one of claims 1 to 3, wherein the second time is a time after the convergence of a transient increase in 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 diagnosis device according to claim 4, wherein the second time is a time after the convergence of a transient increase in 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 diagnosis device for diagnosing degradation of a semiconductor module including a semiconductor element having a first main electrode and a second main electrode, comprising: a voltage measurement unit that measures a 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 a voltage between the second main terminal and a reference terminal that detects the potential of the second main electrode; and a diagnosis processing unit that diagnoses degradation of the semiconductor module based on the measurement results of the voltage measurement unit, wherein the voltage measurement unit measures voltage from a first time point immediately after the start of flow of main current to the semiconductor module, and the diagnosis processing unit diagnoses degradation of a bonding material bonded to the first main electrode based on a comparison between the first time point and a second time point at which the voltage measurement unit measures a voltage at which the result of comparing the first voltage measured at the first time point with the first voltage measured at the first time point is equal to or greater than a predetermined reference value.

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

9. A degradation diagnosis device according to claim 7 or 8, wherein the reference value is a value calculated based on a comparison of the first voltage and the second voltage when the semiconductor module is in a healthy state, where the second voltage is the voltage when a transient increase in the voltage between the first main terminal and the second main terminal or the voltage between the reference terminal and the second main terminal has subsided.

10. A deterioration diagnosis device as described in claim 4 or any one of claims 6 to 9, wherein the diagnostic processing unit diagnoses deterioration of the joint between the wiring and the second main electrode based on the value of the first voltage.

11. The degradation diagnosis device according to claim 1, wherein the first time is a time after the time immediately after the supply of main current to the semiconductor module is initiated, the second time is a time within a period during which the voltage between the first main terminal and the second main terminal or the voltage between the reference terminal and the second main terminal is transiently rising, 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 at the time immediately after the supply of main current to the semiconductor module is initiated, and the diagnosis processing unit diagnoses degradation of the junction between the wiring and the second main electrode based on the value 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 measured by the voltage measurement unit at the time immediately after the supply of main current to the semiconductor module is initiated.

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

13. The deterioration diagnosis device described in claim 11, wherein the diagnostic processing unit diagnoses deterioration of the joining material based on the result of comparing the first voltage with a predetermined first reference value and the result of comparing the second voltage with a predetermined second reference value.

14. A semiconductor device comprising the degradation diagnosis device according to any one of claims 1 to 13 and a semiconductor module that is the subject of degradation diagnosis.

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