Semiconductor equipment

Abstract

This disclosure aims to provide a deterioration detection device and a semiconductor device that can detect deterioration of an object without being affected by the object's deterioration state. [Solution] The degradation detection device 11 includes a first thermoelectric element 111 installed at a first position 121a-1 of the semiconductor module 12, a second thermoelectric element 112 positioned at a second position 121a-2 different from the first position 121a-1 on the semiconductor module 12, a light-emitting diode 113 electrically connected to the first thermoelectric element 111 and the second thermoelectric element 112, a phototransistor 114 that detects the light emitted by the light-emitting diode 113, and a detection circuit 115 that detects the degradation of the semiconductor module 12 based on the light detection value in the phototransistor 114.

Description

Technical Field

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[0001] The present disclosure relates to a deterioration detection device and a semiconductor device that detect deterioration of a detection target that generates heat during operation.

Background Art

[0002] A semiconductor device is known in which a semiconductor element, which is one of the elements that generate heat during operation, is mounted on an insulating wiring board and housed in one package in consideration of heat dissipation and insulation. In such a semiconductor device, the semiconductor element is mounted on the insulating wiring board by, for example, soldering. The semiconductor element, insulating wiring board, solder, and other materials used in the semiconductor device may have different expansion rates due to temperature changes. In this case, for example, physical stress is applied between the materials used in the semiconductor device every time a temperature change occurs due to the heat generated by the operation of the semiconductor element. As a result of the accumulation of this physical stress, cracks or peeling may occur between the materials. In this case, it leads to changes over time in the semiconductor device and ultimately to the destruction of the semiconductor device.

[0003] There are various methods such as observing temperature changes with a temperature sensor to predict changes over time in a semiconductor device. Patent Document 1 discloses a "power module that can detect an increase in the temperature of a power semiconductor element due to deterioration of a solder layer or the like at an early stage by only simple comparison operations and can estimate the life at low cost with a simple structure."

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, conventional methods have a problem in that, because the semiconductor element and the detection circuit are electrically connected, if the semiconductor element included in the degradation detection target is destroyed, the detection circuit may also be destroyed.

[0006] The purpose of this disclosure is to provide a deterioration detection device and a semiconductor device that can detect deterioration of an object regardless of the object's deterioration state. [Means for solving the problem]

[0007] To achieve the above objective, a deterioration detection device according to one aspect of the present disclosure comprises a first thermoelectric element installed at a first position on the object to be detected, a second thermoelectric element positioned on the object at a second position different from the first position, a light-emitting element electrically connected to the first thermoelectric element and the second thermoelectric element, a photodetector for detecting light emitted by the light-emitting element, and a detection circuit for detecting deterioration of the object to be detected based on the photodetector's photodetector value.

[0008] Furthermore, in order to achieve the above objective, a semiconductor device according to one aspect of the present disclosure comprises a degradation detection device according to one aspect of the present disclosure and the object to be detected. [Effects of the Invention]

[0009] According to each aspect of this disclosure, deterioration of an object can be detected without being affected by the deterioration state of the object. [Brief explanation of the drawing]

[0010] [Figure 1] This is a block diagram showing an example of a schematic configuration of a degradation detection device and a semiconductor device according to one embodiment of the present disclosure. [Figure 2] This figure illustrates the schematic configuration of a semiconductor device and the degradation detection operation of a degradation detection device according to one embodiment of the present disclosure, and shows a schematic cross-section of an example of a state in which no cracks have occurred in the solder layer provided in the degradation detection device, and an example of the temperature distribution in that state. [Figure 3]This figure illustrates the degradation detection operation of a degradation detection device according to one embodiment of the present disclosure, and shows an example of the characteristics of the amount of light emitted with respect to voltage of a light-emitting element provided in the degradation detection device, and the forward voltage when no cracks have occurred in the solder layer. [Figure 4] This figure illustrates the degradation detection operation of a degradation detection device according to one embodiment of the present disclosure, and schematically shows a cross-sectional view of an example of a state in which a crack has occurred in the solder layer provided in the degradation detection device, and a figure showing an example of the temperature distribution in said state. [Figure 5] This figure illustrates the degradation detection operation of a degradation detection device according to one embodiment of the present disclosure, and is a schematic plan view showing a state in which a crack has occurred in the solder layer provided in the degradation detection device (the state shown in Figure 4). [Figure 6] This figure illustrates the degradation detection operation of a degradation detection device according to one embodiment of the present disclosure, and shows an example of the characteristics of the amount of light emitted with respect to voltage of a light-emitting element provided in the degradation detection device, and the forward voltage when a crack occurs in the solder layer. [Figure 7] This figure illustrates the degradation detection operation of a degradation detection device according to one embodiment of the present disclosure, and schematically shows a cross-sectional view of an example of a state in which a crack has progressed in a solder layer provided in the degradation detection device, and a figure of an example of the temperature distribution in said state. [Figure 8] This figure illustrates the degradation detection operation of a degradation detection device according to one embodiment of the present disclosure, and is a schematic plan view showing the state in which a crack has progressed in the solder layer provided in the degradation detection device (the state shown in Figure 7). [Figure 9] This is a schematic perspective view showing an example of the appearance of a semiconductor device according to Example 1 of one embodiment of the present disclosure. [Figure 10] This is a schematic perspective view showing an example of the internal configuration of a semiconductor module provided in a semiconductor device according to Example 1 of one embodiment of the present disclosure. [Figure 11] This is a schematic side view showing a part of a semiconductor module provided in a semiconductor device according to Example 1 of one embodiment of the present disclosure. [Figure 12] This is a schematic perspective view showing an example of the appearance of a semiconductor device according to Example 2 of one embodiment of the present disclosure. [Figure 13] FIG. 2 is a perspective view schematically showing an example of an internal configuration of a semiconductor module provided in a semiconductor device according to Example 2 of an embodiment of the present disclosure. [Figure 14] FIG. 5 is a side view schematically showing a part of a semiconductor module provided in a semiconductor device according to Example 2 of an embodiment of the present disclosure. MODE FOR CARRYING OUT THE INVENTION

[0011] A mode for carrying out the present disclosure will be described with reference to the drawings. Note that in each drawing, the dimensions and scales of each element may differ from those of an actual product. Further, the mode described below is an exemplary mode assumed when implementing the present disclosure. Therefore, the scope of the present disclosure is not limited to the mode exemplified below.

[0012] A deterioration detection device and a semiconductor device according to an embodiment of the present disclosure will be described with reference to FIGS. 1 to 14.

[0013] 1-1. Configuration of Deterioration Detection Device: [[ID=二十二]] The schematic configuration of the deterioration detection device 11 according to the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a circuit diagram showing an example of the schematic configuration of the deterioration detection device 11 according to the present embodiment and a semiconductor device 1 including the deterioration detection device 11.

[0014] As shown in FIG. 1, the deterioration detection device 11 includes a first thermoelectric element 111 installed at a first position 121a-1 (not shown in FIG. 1, see FIG. 2) of an insulated gate bipolar transistor (IGBT) 121 corresponding to an example of a semiconductor element. The deterioration detection device 11 includes a second thermoelectric element 112 disposed on the IGBT 121 at a second position 121a-2 (not shown in FIG. 1, see FIG. 2) different from the first position 121a-1.

[0015] The deterioration detection device 11 includes a light-emitting diode 113 electrically connected to a first thermoelectric element 111 and a second thermoelectric element 112. The light-emitting diode 113 corresponds to an example of a light-emitting element. The positive terminal (+) (an example of an output) of the first thermoelectric element 111 is connected to the anode of the light-emitting diode 113, and the positive terminal (+) (an example of an output) of the second thermoelectric element 112 is connected to the cathode of the light-emitting diode 113.

[0016] The deterioration detection device 11 includes a phototransistor (an example of a light detection element) 114 that detects light emitted from the light-emitting diode 113. The phototransistor 114 is electrically insulated from the light-emitting diode 113. The light-emitting diode 113 and the phototransistor 114 may be provided individually or may be constituted by a packaged photocoupler.

[0017] The deterioration detection device 11 includes a detection circuit 115 that detects deterioration of the semiconductor module 12 based on the light detection value in the phototransistor 114. The detection circuit 115 is electrically insulated from a semiconductor module 12 (details will be described later), which corresponds to an example of a detection target. The collector and emitter of the phototransistor 114 are connected to the detection circuit 115. For this reason, the detection circuit 115 detects the amount of collector current flowing through the phototransistor 114 according to the light reception amount as the light detection value. A first threshold value and a second threshold value are set in the detection circuit 115. The second threshold value is set to a value higher than the first threshold value. When light is detected by the phototransistor 114 and the light detection value is higher than the first threshold value and lower than the second threshold value, the detection circuit 115 notifies the outside that a change over time due to deterioration has occurred in the detection target (in this embodiment, the semiconductor module 12 (details will be described later)). Further, when the light detection value is higher than the second threshold value, the detection circuit 115 notifies the outside that the detection target has reached the end of its life.

[0018] The detection circuit 115 notifies the external system that a change over time is occurring in the object being detected or that it has reached the end of its lifespan by outputting a detection signal Sd to the outside. The detection circuit 115 may output different detection signals Sd depending on whether it detects deterioration over time or that it has reached the end of its lifespan. For example, the detection circuit 115 may output a detection signal Sd that causes a light-emitting element (not shown) to blink when it detects deterioration over time, and output a detection signal Sd that causes the said light-emitting element to light up when it detects that it has reached the end of its lifespan.

[0019] The degradation detection device 11 includes a power supply 15 that supplies power to the detection circuit 115. The power supply 15 is, for example, a DC power supply.

[0020] 1-2. Semiconductor device configuration: The schematic configuration of the semiconductor device 1 according to this embodiment will be explained with reference to Figures 1 and 2. The semiconductor device 1 is used, for example, in a switching power supply and is a device that includes semiconductor elements such as IGBTs and metal-oxide-semiconductor field-effect transistors (MOSFETs).

[0021] Figure 2 is a schematic diagram showing a cross-section of a state in which no cracks have occurred in the solder layer 123 provided in the degradation detection device 11, and an example of the temperature distribution in that state. The upper part of Figure 2 schematically shows a cross-section of a part of the degradation detection device 11 provided in the semiconductor device 1, and the lower part of Figure 2 shows an example of the temperature distribution on the surface 121a of the IGBT 121 on which the first thermoelectric element 111 and the second thermoelectric element 112 are arranged.

[0022] As shown in Figures 1 and 2, the semiconductor device 1 comprises a semiconductor module 12 having an IGBT 121, a light-emitting diode 113, an insulating wiring substrate 122 (not shown in Figure 1) on which the IGBT 121 is arranged, and a conductive solder layer (an example of an adhesive layer) 123 (not shown in Figure 1) that adheres the IGBT 121 to the insulating wiring substrate 122. The semiconductor module 12 corresponds to an example of an object to be detected. The solder layer 123 is formed of, for example, tin-silver (SnAg) solder. The insulating wiring substrate 122 is arranged in a state where it is thermally connected to a heat-dissipating metal plate (not shown) for dissipating the heat generated by the IGBT 121.

[0023] IGBT121 is an example of a semiconductor element having a surface 121a (see Figure 2) on which the first thermoelectric element 111 and the second thermoelectric element 112 are arranged. This semiconductor element is an element that generates heat when operating, and is not limited to IGBT121; for example, it may be a power MOSFET or the like.

[0024] The first position 121a-1 is a position close to the center of the surface 121a of the IGBT 121, and the second position 121a-2 is a position close to the periphery of the surface 121a. The first position 121a-1 is a position on the surface 121a that is closer to the center than to the periphery. The second position 121a-2 is a position on the surface 121a that is closer to the periphery than to the center. Here, viewing the predetermined plane in a direction perpendicular to the predetermined plane is referred to as a "plan view". The first position 121a-1 is, for example, the center of the surface 121a in a plan view of the surface 121a. Therefore, the first thermoelectric element 111 is mounted on a predetermined region of the surface 121a that includes the center. The second position 121a-2 is a position adjacent to one of the four edges of the IGBT 121 in a plan view of the surface 121a. The position adjacent to the edge in question lies, for example, on a virtual line connecting the midpoint in the direction of extension of the edge and the center of the surface 121a. The second thermoelectric element 112 is positioned so as not to protrude from the surface 121a at the position adjacent to the edge in question.

[0025] The light-emitting portion (not shown) of the light-emitting diode 113 and the light-receiving portion (not shown) of the phototransistor 114 are arranged opposite each other. This allows the phototransistor 114 to efficiently receive the light signal output from the light-emitting diode 113.

[0026] Returning to Figure 1, the semiconductor device 1 includes a drive circuit 13 for driving the IGBT 121, a power supply 14 (an example of a first power supply) for supplying power to the drive circuit 13, a detection circuit 115, and a power supply 15 (an example of a second power supply) which is electrically isolated from power supply 14 and supplies power to the detection circuit 115. Furthermore, the semiconductor device 1 includes a power supply 16 which is electrically isolated from power supplies 14 and 15 and supplies power to the IGBT 121.

[0027] The output of the drive circuit 13 is connected to the gate of the IGBT 121. The reference potential section (e.g., the ground terminal) of the drive circuit 13, which is maintained at the reference potential, is connected to the emitter of the IGBT 121. The negative side of the power supply 16 is connected to the emitter of the IGBT 121, and the positive side of the power supply 16 is connected to the collector of the IGBT 121. In this way, the power supply 16 is connected between the collector and emitter of the IGBT 121. The IGBT 121 switches in response to the drive signal output by the drive circuit 13 and input to its gate. When the IGBT 121 is ON, it receives current from the power supply 16 as collector current and flows it to, for example, a load device (not shown).

[0028] The negative terminals (-) of the first thermoelectric element 111 and the second thermoelectric element 112 are connected to the reference potential section of the drive circuit 13, the emitter of the IGBT 121, and the negative terminal side of the power supply 16. The positive terminal (+) of the first thermoelectric element 111 is connected to the cathode of the light-emitting diode 113, and the positive terminal of the second thermoelectric element 112 is connected to the anode of the light-emitting diode 113. Therefore, the negative terminals (-) of the first thermoelectric element 111 and the second thermoelectric element 112 are connected to each other. The high-power side of the electromotive force generated when heat is applied to the first thermoelectric element 111 is the positive terminal (+) of the first thermoelectric element 111, and the low-power side of the electromotive force is the negative terminal (-) of the first thermoelectric element 111. Similarly, when heat is applied to the second thermoelectric element 112, the high-power side of the electromotive force generated is the positive terminal (+) of the second thermoelectric element 112, and the low-power side of the electromotive force is the negative terminal (-) of the second thermoelectric element 112.

[0029] Thus, the semiconductor device 1 includes a first thermoelectric element 111, a second thermoelectric element 112, a light-emitting diode 113, a phototransistor 114, a detection circuit 115, and a power supply 15, all of which are provided in the degradation detection device 11. Therefore, the semiconductor device 1 comprises the degradation detection device 11 according to this embodiment and a semiconductor module 12 as the object to be detected.

[0030] The semiconductor device 1 is equipped with power supplies 14, 15, and 16 that are electrically isolated from each other. Specifically, the power lines (i.e., the positive terminals) of the power supplies 14, 15, and 16 are electrically isolated from each other. Furthermore, the IGBT 121 and the detection circuit 115 are photocoupled by the light-emitting diode 113 and the phototransistor 114, and are not electrically coupled. Therefore, the possibility that degradation or damage to the semiconductor module 12 due to heat generation from the IGBT 121 may affect the detection circuit 115 is reduced. As a result, the degradation detection device 11 and the semiconductor device 1 can detect the degradation of the semiconductor module 12 without being affected by the degradation state of the semiconductor module 12.

[0031] 1-3. Degradation detection operation of the degradation detection device: The degradation detection operation of the degradation detection device according to this embodiment will be explained with reference to Figure 1 and Figures 2 to 8. In this embodiment, cracks occurring in the solder layer 123 provided on the semiconductor module 12 will be used as an example of degradation to explain the degradation detection operation of the degradation detection device.

[0032] 1-3-1. If the object being detected has not deteriorated: The operation of the degradation detection device 11 when no degradation has occurred in the semiconductor module 12, which is the object to be detected for degradation, will be explained with reference to Figure 1, and using Figures 2 and 3. Figure 3 is a diagram showing an example of the characteristics of the amount of light emitted with respect to the forward voltage of the light-emitting diode 113 provided in the degradation detection device 11. In the graph shown in Figure 3, the horizontal axis represents the forward voltage applied to the light-emitting diode 113, and the vertical axis of the graph represents the amount of light emitted by the light-emitting diode 113.

[0033] The IGBT121 has a structure in which, for example, the gate and emitter are located on the surface 121a side, and the collector is located on the back side of the surface 121a (i.e., the side that contacts the solder layer 123). Therefore, when the IGBT121 is ON, the current input from the power supply 16 flows through the insulating wiring board 122 and the solder layer 123 from the collector to the emitter in the thickness direction of the IGBT121. When this current (i.e., collector current) flows and the IGBT121 operates, the IGBT121 generates heat. The heat generated in the IGBT121 is dissipated to the heat dissipation metal plate (not shown) side via the solder layer 123 and the insulating wiring board 122.

[0034] Even with heat dissipation from the heat-dissipating metal plate, the temperature of the IGBT121 rises compared to when it is not operating. As the temperature of the IGBT121 rises, the surface 121a on which the first thermoelectric element 111 and the second thermoelectric element 112 are located has a temperature distribution in which the first position 121a-1 is hotter than the second position 121a-2, as shown in the lower part of Figure 2. Thus, the second position 121a-2 is a position that is hotter than the first position 121a-1. As a result, the temperature T121a-1 detected by the first thermoelectric element 111 located at the first position 121a-1 is higher than the temperature T121a-2 detected by the second thermoelectric element 112 located at the second position 121a-2. If no cracks occur in the solder layer 123, the difference between the temperatures T121a-1 and T121a-2 detected by the first thermoelectric element 111 and the second thermoelectric element 112, respectively, is, for example, a temperature difference ΔT1.

[0035] The voltage output by the first thermoelectric element 111 is higher than the voltage output by the second thermoelectric element 112. Since the negative terminals (-) of the first thermoelectric element 111 and the second thermoelectric element 112 are connected to each other, the potential difference between the positive terminals (+) output by the first thermoelectric element 111 and the second thermoelectric element 112 becomes the voltage applied to the anode and cathode of the light-emitting diode 113. In other words, the voltage applied to the anode and cathode of the light-emitting diode 113 corresponds to the temperature difference ΔT1. Since the potential applied to the anode of the light-emitting diode 113 is higher than the potential applied to the cathode of the light-emitting diode 113, a forward voltage is applied to the light-emitting diode 113.

[0036] As shown in Figure 3, if no cracks occur in the solder layer 123, the voltage applied to the light-emitting diode 113 corresponding to the temperature difference ΔT1 (see Figure 2) in the IGBT 121 is a forward voltage V1 that is lower than the threshold voltage Vth of the light-emitting diode 113. Therefore, the light-emitting diode 113 does not emit light (the amount of light emitted is 0), and the amount of light received by the phototransistor 114 is 0. As a result, no collector current corresponding to the light detection value flows through the phototransistor 114. Consequently, the detection circuit 115 (see Figure 1) does not detect the degradation of the semiconductor module 12 and therefore does not output a detection signal Sd.

[0037] As the IGBT121 continues to operate, its temperature rises, and the temperature difference ΔT1 between the first thermoelectric element 111 and the second thermoelectric element 112 increases, causing the voltage applied to the light-emitting diode 113 to exceed the threshold voltage Vth. In this case, the light-emitting diode 113 emits light, and collector current flows through the phototransistor 114. The detection circuit 115 does not output a detection signal Sd as long as the collector current flowing through the phototransistor 114 is lower than the first threshold set in the detection circuit 115.

[0038] 1-3-2. When the deterioration of the object being detected is in its initial state: The degradation detection operation of the degradation detection device 11 when the degradation of the semiconductor module 12, which is the object to be detected, is in its initial state will be explained using Figures 4 to 6 with reference to Figure 1. Figure 4 is a diagram illustrating the state in which a crack CK has occurred in the solder layer 123 provided in the degradation detection device 11. The upper part of Figure 4 schematically shows a cross-section of the degradation detection device 11 in the state in which a crack CK has occurred in the solder layer 123, and the lower part of Figure 4 illustrates an example of the temperature distribution on the surface 121a of the IGBT 121. Figure 5 is a diagram schematically showing the plane of the solder layer 123 in the initial state in which a crack CK has occurred. Figure 6 is a diagram illustrating an example of the characteristics of the amount of light emitted with respect to voltage of the light-emitting diode 113 provided in the degradation detection device 11. In the graph shown in Figure 6, the horizontal axis represents the voltage applied to the light-emitting diode 113, and the vertical axis represents the amount of light emitted by the light-emitting diode 113.

[0039] Incidentally, when the IGBT121 switches (i.e., repeatedly switches between on and off states), the heat generated and the temperature rise that occur repeatedly cause stress in the solder layer 123 between the IGBT121 and the insulating wiring board 122 at the joints of each part of the semiconductor module 12. When this stress is repeatedly applied to the solder layer 123, cracks CK may occur in the solder layer 123, as shown in the upper part of Figure 4. The silicon that makes up the IGBT121 and the material that forms the solder layer 123 (tin or silver in this embodiment) have different coefficients of thermal expansion. Therefore, when the temperature of the IGBT121 rises, the difference in the coefficients of thermal expansion is generated internally as stress. When the internally generated stress is applied to the solder layer 123, cracks CK occur.

[0040] In SnAg-based solder, cracks tend to occur more in the center of the solder layer than at the periphery. Therefore, due to temperature changes (power cycling) caused by the repeated operation and shutdown of the semiconductor module 12 (IGBT 121 being on and off), cracks CK begin to form in the center of the solder layer 123, as shown in the upper part of Figure 4 and Figure 5. The cracks CK in the solder layer 123 hinder the dissipation of heat generated in the IGBT 121. As a result, the heat generated in the IGBT 121 is less likely to dissipate in the center than at the periphery. Consequently, as shown in the lower part of Figure 4, the temperature T121a-1 detected by the first thermoelectric element 111 located at the first position 121a-1 is higher after the cracks CK have formed than before. On the other hand, no cracks form at the periphery of the IGBT 121. Therefore, the amount of heat dissipated at the periphery of the IGBT 121 is almost the same before and after the cracks CK have formed. As a result, the temperature T121a-2 detected by the second thermoelectric element 112 located at the second position 121a-2 is almost the same before and after the crack CK occurs. Consequently, the temperature difference ΔT2 between the temperatures T121a-1 and T121a-2 detected by the first thermoelectric element 111 and the second thermoelectric element 112 is larger after the crack CK occurs than before. As a result, as shown in Figure 5, the voltage applied to the light-emitting diode 113 in response to the temperature difference ΔT2 becomes a forward voltage V2 that is higher than the threshold voltage Vth of the light-emitting diode 113.

[0041] The period from when the crack CK begins to form until a predetermined time has elapsed corresponds to, for example, the initial state in which the semiconductor module 12 is beginning to undergo aging changes. In this initial state, the temperature difference ΔT2 between the temperature T121a-1 detected by the first thermoelectric element 111 and the temperature detected by the second thermoelectric element 112 is higher than the threshold temperature Tth1 corresponding to the first threshold set in the detection circuit 115, and lower than the threshold temperature Tth2 corresponding to the second threshold.

[0042] When a forward voltage V2 is applied, the light-emitting diode 113 emits light, causing a collector current to flow through the phototransistor 114. This collector current, which corresponds to the photodetection value, is greater than the first threshold and less than the second threshold. As a result, the detection circuit 115 outputs a detection signal Sd to indicate that a change over time is occurring in this initial state. As the crack CK progresses, the temperature of the semiconductor module 12 gradually rises, potentially leading to device failure due to overheating. The degradation detection device 11 and the semiconductor device 1 equipped with the degradation detection device 11 can notify the semiconductor module 12 of the occurrence of a change over time using the detection signal Sd at the initial stage of the change, thereby preventing damage to the semiconductor module 12.

[0043] 1-3-3. If the deterioration of the object being detected has progressed beyond its initial state: The degradation detection operation of the degradation detection device 11 when the degradation of the semiconductor module 12, which is the object to be detected, has progressed beyond its initial state will be explained with reference to Figures 1 and 6, and with reference to Figures 7 and 8. Figure 7 is a diagram illustrating the case when a crack CK that has occurred in the solder layer 123 provided in the degradation detection device 11 has progressed beyond its initial state. The upper part of Figure 7 schematically shows a cross-section of the degradation detection device 11 in the state where a crack CK has occurred in the solder layer 123, and the lower part of Figure 7 shows an example of the temperature distribution on the surface 121a of the IGBT 121. Figure 8 is a diagram schematically showing the plane of the solder layer 123 where the crack CK has progressed beyond its initial state.

[0044] If the switching operation of IGBT121 continues during the initial state in which crack CK occurs, the area of ​​crack CK in the solder layer 123 will expand, as shown in the upper part of Figure 7 and Figure 8. As a result, the heat generated in IGBT121 will be less easily dissipated than in the initial state. Consequently, as shown in the lower part of Figure 7, the temperature T121a-1 detected by the first thermoelectric element 111 located at the first position 121a-1 will be higher than in the initial state in which crack CK began to occur. On the other hand, no crack has occurred at the periphery of IGBT121. Therefore, the amount of heat dissipated at the periphery of IGBT121 will be almost the same before and after crack CK occurs. Consequently, the temperature T121a-2 detected by the second thermoelectric element 112 located at the second position 121a-2 will be almost the same before and after crack CK occurs. As a result, the temperature difference ΔT3 between temperatures T121a-1 and T121a-2 detected by the first thermoelectric element 111 and the second thermoelectric element 112, respectively, becomes larger than the temperature difference ΔT2 in the initial state when the crack CK begins to form. Consequently, as shown in Figure 6, the voltage applied to the light-emitting diode 113 in response to the temperature difference ΔT3 becomes a forward voltage V3, which is higher than the threshold voltage Vth and forward voltage V2 of the light-emitting diode 113.

[0045] When the crack CK has progressed beyond its initial state, the temperature difference ΔT3 between the temperature T121a-1 detected by the first thermoelectric element 111 and the temperature detected by the second thermoelectric element 112 becomes higher than the threshold temperature Tth2 corresponding to the second threshold set in the detection circuit 115.

[0046] When a forward voltage V3 is applied, the light-emitting diode 113 emits light, causing a collector current to flow through the phototransistor 114. This collector current, which corresponds to the photodetection value, is greater than the second threshold. As a result, the detection circuit 115 outputs a detection signal Sd to indicate that the semiconductor module has reached the end of its lifespan when the crack CK has progressed beyond its initial state. In this embodiment, the point at which the semiconductor module 12 reaches the end of its lifespan is set, for example, before the semiconductor module 12 is damaged. Therefore, the degradation detection device 11 and the semiconductor device 1 equipped with the degradation detection device 11 can notify that the semiconductor module 12 has reached the end of its lifespan by the detection signal Sd when it reaches the end of its lifespan before it is damaged, thus preventing the semiconductor module 12 from being damaged.

[0047] 1-4. Effects: The effects of the degradation detection device and semiconductor device according to this embodiment will be described. In Patent Document 1, peripheral circuits such as a DC constant current source and a life estimation circuit are electrically connected to the main circuit, which is a semiconductor element. If the main circuit is damaged due to aging or other factors, the high current or high voltage applied to the main circuit may be unintentionally applied to the peripheral circuits. Peripheral circuits have lower tolerance to both current and voltage compared to the main circuit. Therefore, there is a problem that if high current or high voltage is applied to the peripheral circuits, they are highly likely to be damaged. If the peripheral circuits are damaged along with the main circuit, it will be necessary to replace the main circuit and peripheral circuits during repair.

[0048] Furthermore, the power module disclosed in Patent Document 1 requires complex components such as a DC constant current source and a life estimation circuit, which leads to high manufacturing costs and consequently high selling prices. Therefore, the application of the power module disclosed in Patent Document 1 is limited to certain products, such as those in the high-price range, and its application to products in the popular price range is difficult.

[0049] In contrast, the degradation detection device 11 according to this embodiment includes a power supply 15 that is electrically isolated from the power supply 16 for the IGBT 121, which corresponds to the main circuit, and the power supply 14 for the drive circuit 13 that drives the IGBT 121. Furthermore, the degradation detection device 11 has a first thermoelectric element 111 and a second thermoelectric element 112 that detect the temperature of the IGBT 121, and a detection circuit 115 that detects the degradation of the semiconductor module 12 having the IGBT 121, which are photocoupled and electrically isolated. As a result, the degradation detection device 11 and the semiconductor device 1 equipped with the degradation detection device 11 can detect the degradation of the semiconductor module 12 without being affected by changes over time or damage to the semiconductor module 12 having the IGBT 121.

[0050] Furthermore, the degradation detection device 11 can detect the degradation of the semiconductor module 12 based on the voltage corresponding to the temperature difference between the first thermoelectric element 111 and the second thermoelectric element 112 arranged on the surface 121a of the IGBT 121. As a result, the degradation detection device 11 and the semiconductor device 1 can be equipped with functions for detecting and notifying changes over time and the end of life of the semiconductor module 12 without the need for a DC constant current source or a life estimation circuit.

[0051] Thus, the degradation detection device 11 and the semiconductor device 1 can detect the degradation of the semiconductor module 12 without being affected by the degradation state of the semiconductor module 12. Furthermore, the degradation detection device 11 and the semiconductor device 1 can be manufactured at a lower cost by reducing manufacturing costs.

[0052] 1-5. Example 1: The degradation detection device and semiconductor device according to Embodiment 1 of this embodiment will be described with reference to Figures 1 and 2, and with reference to Figures 9 to 11. The degradation detection device and semiconductor device according to this embodiment have the same circuit configuration as the degradation detection device 11 and semiconductor device 1 shown in Figure 1. In the description of the degradation detection device and semiconductor device according to this embodiment, components that perform the same actions and functions as the degradation detection device 11 and semiconductor device 1 according to this embodiment will be given the same reference numerals, and their descriptions will be omitted.

[0053] Figure 9 is a schematic perspective view showing an example of the external appearance of the semiconductor device 1A according to this embodiment. Figure 10 is a schematic perspective view showing an example of the main internal components of the semiconductor module 12 provided in the semiconductor device 1A according to this embodiment. In Figure 10, for ease of understanding, the top surface and three sides of the outer casing 128 provided on the semiconductor module 12 are omitted. Figure 11 is a schematic side view showing a part of the semiconductor module 12 provided in the semiconductor device 1A according to this embodiment.

[0054] As shown in Figure 9, the semiconductor device 1A according to this embodiment comprises a semiconductor module 12, a drive circuit 13, and a detection circuit 115. The semiconductor module 12 is provided independently of the drive circuit 13 and the detection circuit 115. The drive circuit 13 and the detection circuit 115 are provided independently of each other.

[0055] The semiconductor device 1A is equipped with an optical fiber 18 with a connector 17 at one end. The semiconductor module 12 and the detection circuit 115 are connected by the optical fiber 18.

[0056] The semiconductor module 12 has an outer casing 128 that contains an IGBT 121 (see Figure 1) and the like. The semiconductor module 12 has control terminals 124a and 124b, one end of which is electrically connected to the gate of the IGBT 121 and the other end of which is exposed to the outside from the outer casing 128. The semiconductor module 12 also has control terminals 124c and 124c, one end of which is electrically connected to the emitter of the IGBT 121 and the other end of which is exposed to the outside from the outer casing 128.

[0057] The semiconductor module 12 and the drive circuit 13 are connected by control wiring 19a and 19b. One end of control wiring 19a is connected to the other end of control terminals 124a and 124b, and the other end of control wiring 19a is connected to the drive circuit 13. One end of control wiring 19b is connected to the other end of control terminals 124c and 124c, and the other end of control wiring 19b is connected to the drive circuit 13.

[0058] As shown in Figure 10, the semiconductor module 12 includes a heat-dissipating metal plate 125 located at its bottom. The outer casing 128 surrounds the heat-dissipating metal plate 125. The outer casing 128 and the heat-dissipating metal plate 125 form a predetermined internal space. Within this internal space, the semiconductor module 12 includes insulating wiring boards 122 and 126 fixed to the heat-dissipating metal plate 125. The insulating wiring boards 122 and 126 are thermally connected to the heat-dissipating metal plate 125.

[0059] An IGBT 121 is placed on the insulating wiring board 122, fixed to the insulating wiring board 122 by a solder layer 123. The IGBT 121 is thermally connected to the insulating wiring board 122. A first thermoelectric element 111 is placed at a first position 121a-1 (see Figure 2) on the surface 121a of the IGBT 121. A second thermoelectric element 112 is placed at a second position 121a-2 (see Figure 2) on the surface 121a of the IGBT 121.

[0060] A light-emitting diode 113 and an adapter 127 are fixed to the insulated wiring board 126. The anode of the light-emitting diode 113 is connected to the positive terminal (+) of the first thermoelectric element 111 (see Figure 2) by a wiring wire 116a. The cathode of the light-emitting diode 113 is connected to the positive terminal (+) of the second thermoelectric element 112 (see Figure 2) by a wiring wire 116b. The negative terminal (-) of the first thermoelectric element 111 (see Figure 2) and the negative terminal (-) of the second thermoelectric element 112 (see Figure 2) are connected by a wiring wire 116c.

[0061] As shown in Figure 11, an opening 128a is formed in a part of the side surface of the outer casing 128. The adapter 127 is positioned exposed to the opening 128a. A connector 17 (not shown in Figure 11, see Figure 9) is connected to the adapter 127 exposed to the opening 128a in an optically coupled state. The other end of the optical fiber 18 (not shown in Figure 11, see Figure 9) is connected to the outer casing 115a in an optically coupled state to a phototransistor 114 (not shown in Figures 9 to 11, see Figure 1) provided inside the outer casing 115a of the detection circuit 115. As a result, the light-emitting diode 113 and the phototransistor 114 are optically coupled via the adapter 127, connector 17, and optical fiber 18.

[0062] The semiconductor device 1A according to this embodiment includes a first thermoelectric element 111, a second thermoelectric element 112, and a light-emitting diode 113 arranged within the casing 128 of the semiconductor module 12, a detection circuit 115, and a phototransistor 114 arranged within the casing 115a of the detection circuit 115, thus comprising a degradation detection device 11.

[0063] Therefore, the degradation detection device 11 and semiconductor device 1A according to this embodiment can achieve the same effects as the degradation detection device 11 and semiconductor device 1 according to this embodiment.

[0064] 1-6. Example 2: The degradation detection device and semiconductor device according to Embodiment 2 of this embodiment will be described with reference to Figure 1 and Figures 12 to 14. The degradation detection device and semiconductor device according to this embodiment have the same circuit configuration as the degradation detection device 11 and semiconductor device 1 shown in Figure 1. In the description of the degradation detection device and semiconductor device according to this embodiment, components that perform the same actions and functions as the degradation detection device 11 and semiconductor devices 1, 1A according to this embodiment or Embodiment 1 will be denoted by the same reference numerals and their descriptions will be omitted.

[0065] Figure 12 is a schematic perspective view showing an example of the external appearance of the semiconductor device 1B according to this embodiment. Figure 13 is a schematic perspective view showing an example of the main internal components of the semiconductor module 12 provided in the semiconductor device 1B according to this embodiment. In Figure 13, for ease of understanding, the outer casing 128 provided on the semiconductor module 12 is shown as a dashed and transparent line. Figure 14 is a schematic side view showing a part of the semiconductor module 12 provided in the semiconductor device 1B according to this embodiment.

[0066] As shown in Figure 12, the semiconductor device 1B according to this embodiment comprises a semiconductor module 12 and a mixed-signal circuit 10 having a drive circuit 13 and a detection circuit 115 (not shown in Figure 12, see Figure 1). The semiconductor module 12 is provided independently of the mixed-signal circuit 10. Although not shown, a power supply 14 (see Figure 1) that supplies power to the drive circuit 13 and a power supply 15 (see Figure 1) that supplies power to the detection circuit 115 are electrically isolated and provided in the mixed-signal circuit 10. For this reason, the drive circuit 13 and the detection circuit 115 provided in the semiconductor device 1B are electrically isolated.

[0067] The semiconductor module 12 and the mixed-signal circuit 10 are connected by control terminals 124a, 124b, 124c, 124c, and 124e, 124f, which protrude from the outer casing 128. Although not shown in the diagram, the control terminals 124a, 124b, 124c, and 124c are electrically connected to the drive circuit 13 provided in the mixed-signal circuit 10.

[0068] As shown in Figure 12, the semiconductor module 12 in this embodiment has the same internal configuration as the semiconductor module 12 in Embodiment 1, except that the arrangement of the adapter 127 is different. In the semiconductor module 12 in this embodiment, the adapter 127 is arranged on the light-emitting diode 113. The adapter 127 is arranged exposed to an opening (not shown) formed on the upper surface of the outer casing 128.

[0069] As shown in Figure 13, a connector 17 provided at one end of the optical fiber 18 is optically coupled to an adapter 127 (not shown in Figure 13) exposed on the upper surface of the outer casing 128. The other end of the optical fiber 18 is optically coupled to a phototransistor 114 (not shown in Figure 13, see Figure 1) provided within the mixed-signal circuit 10. As a result, the light-emitting diode 113 and the phototransistor 114 are optically coupled via the adapter 127, connector 17, and optical fiber 18.

[0070] The semiconductor device 1B according to this embodiment includes a first thermoelectric element 111, a first thermoelectric element 111 and a light-emitting diode 113 arranged inside the outer casing 128 of the semiconductor module 12, and a detection circuit 115 and a phototransistor 114 provided in the mixed-signal circuit 10, and therefore includes a degradation detection device 11.

[0071] Therefore, the degradation detection device 11 and semiconductor device 1B according to this embodiment can achieve the same effects as the degradation detection device 11 and semiconductor device 1 according to this embodiment.

[0072] As described above, the degradation detection device 11 according to this embodiment includes a first thermoelectric element 111 installed at a first position 121a-1 of the semiconductor module 12, a second thermoelectric element 112 positioned at a second position 121a-2 different from the first position 121a-1 on the semiconductor module 12, a light-emitting diode 113 electrically connected to the first thermoelectric element 111 and the second thermoelectric element 112, a phototransistor 114 for detecting the light emitted by the light-emitting diode 113, and a detection circuit 115 for detecting the degradation of the semiconductor module 12 based on the light detection value in the phototransistor 114.

[0073] Furthermore, the semiconductor device 1 according to this embodiment includes a degradation detection device 11 and a semiconductor module 12 according to this embodiment.

[0074] A degradation detection device 11 and semiconductor device 1 with such a configuration can detect the degradation of the semiconductor module 12 without being affected by the degradation state of the semiconductor module 12.

[0075] This disclosure is not limited to the embodiments described above and can be modified in various ways. In the above embodiment, a semiconductor module 12 was used as an example of an object to be detected for degradation, but this disclosure is not limited to this. For example, the object to be detected for degradation may be an element, device, or apparatus having multiple points that have temperature differences due to operation.

[0076] In the above embodiments, a light-emitting diode was used as an example of a light-emitting element and a phototransistor as an example of a photodetector, but the disclosure is not limited thereto. For example, the light-emitting element may be a semiconductor laser, and the photodetector may be a photodiode.

[0077] In the above embodiment, a first threshold and a second threshold set in the detection circuit 115 are used to notify that a change over time is occurring and that the device has reached the end of its lifespan, but the disclosure is not limited thereto. For example, a plurality of light-emitting elements with different threshold voltages may be provided, and the combination of the illumination of the plurality of light-emitting elements may be used to notify that a change over time is occurring and that the device has reached the end of its lifespan. [Explanation of Symbols]

[0078] 1,1A,1B Semiconductor equipment 10 Mixed-signal circuits 11. Deterioration detection device 12 Semiconductor Modules 13 Drive Circuit 14,15,16 Power supply 17 Connectors 18 Optical Fibers 19a, 19b Control wiring 111 First Thermoelectric Element 112 Second thermoelectric element 113 Light-emitting diodes 114 Phototransistors 115 Detection circuit 115a, 128 Exterior 116a, 116b, 116c Wiring wires 121 IGBT 121a surface 121a-1 First position 121a-2 Second position 122,126 Insulated Wiring Boards 123 Solder layer 124a, 124b, 124c, 124d, 124e, 124f Control terminals 125 Metal plate for heat dissipation 127 adapter 128a opening CK crack Sd detection signal

Claims

1. The first thermoelectric element is installed at the first position of the object to be detected, A second thermoelectric element is positioned in the object to be detected at a second position different from the first position, A light-emitting element electrically connected to the first thermoelectric element and the second thermoelectric element, A photodetector element for detecting the light emitted by the light-emitting element, A detection circuit that detects the deterioration of the object to be detected based on the light detected value in the light detection element. A deterioration detection device equipped with the following features.

2. The second position is a position that is hotter than the first position. The deterioration detection device according to claim 1.

3. The light-emitting element is a light-emitting diode, The output of the first thermoelectric element is connected to the cathode of the light-emitting diode. The output of the second thermoelectric element is connected to the anode of the light-emitting diode. The deterioration detection device according to claim 2.

4. The detection circuit is configured with a first threshold and a second threshold. The detection circuit is When the light is detected by the light detection element and the light detection value is higher than the first threshold and lower than the second threshold, the system notifies the external system that a change due to deterioration is occurring in the object being detected. If the light detection value is higher than the second threshold, the system notifies the external system that the object to be detected has reached the end of its lifespan. The deterioration detection device according to claim 1.

5. A deterioration detection device according to any one of claims 1 to 4, The object to be detected and A semiconductor device equipped with a semiconductor device.

6. The object to be detected includes a semiconductor element on which the first thermoelectric element and the second thermoelectric element are arranged. The first position is a position close to the center of the surface of the semiconductor element. The second position is a position close to the periphery of the surface of the semiconductor element. The semiconductor device according to claim 5.

7. A semiconductor module comprising the semiconductor element, the light-emitting element, an insulating wiring substrate on which the semiconductor element is arranged, and an adhesive layer having conductivity for bonding the semiconductor element to the insulating wiring substrate, A drive circuit for driving the aforementioned semiconductor element, A first power supply that supplies power to the aforementioned drive circuit, The aforementioned detection circuit, The first power supply is electrically isolated from the second power supply which supplies power to the detection circuit. Equipped with, The object to be detected is the semiconductor module. The semiconductor device according to claim 6.

8. The drive circuit and the detection circuit are provided independently of each other. The semiconductor device according to claim 7.

9. The system includes a mixed circuit having the aforementioned drive circuit and the aforementioned detection circuit. The semiconductor device according to claim 7.

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