Transient thermal resistance measuring apparatus and transient thermal resistance measuring method

Abstract

To reduce the switching noise of a heating power source.SOLUTION: A transient thermal resistance measuring apparatus 100 includes a heater power source 1 for generating a heater voltage, a heater current switch 2 provided in a flow path of a heater current, a measuring power source device 3 for supplying a measuring current to a DUT5, and a control device 4 including a measuring section 41 for measuring a voltage Vm across the DUT5 and a control section 42. Thereafter, when a predetermined heating time elapses, an OFF signal is input to the heating current switch 2, and a forced stop signal Sfs is input to the external interrupt terminal Tfs of the heating power supply 1. The heater power source 1 generates the heater voltage V4 by switching when receiving the operation signal converted from the forcible suspension signal Sfs at the operation control node To, and suspends the generation of the heater voltage V4 by an interrupt process when the forcible suspension signal is inputted to the external interrupt node Tfs.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a transient thermal resistance measuring device and a transient thermal resistance measuring method. [Background technology]

[0002] A conventional method for measuring the thermal resistance of a semiconductor device is known. For example, Patent Document 1 discloses a thermal resistance measurement method including the following steps: a first step of supplying a minute current to a semiconductor device under test and measuring a forward voltage drop of the semiconductor device under test; a second step of supplying a test current, which is sufficiently larger than the minute current, and the minute current to the semiconductor device under test in the forward direction and measuring a change characteristic of the forward voltage drop of the semiconductor device under test immediately after the supply of the test current is stopped; a third step of supplying the minute current and the test current to a dummy element having an inductance component substantially equivalent to that of the semiconductor device under test and measuring the voltage characteristics between both ends of the dummy element; a fourth step of correcting an error in the measurement result of the second step from the result of the third step; and a fifth step of calculating the thermal resistance of the semiconductor device under test from the measurement results of the first and fourth steps. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 11-211786 (see especially the abstract) Summary of the Invention [Problem to be solved by the invention]

[0004] However, the above thermal resistance measurement method still has room for improvement. Specifically, the above thermal resistance measurement method inherently introduces errors due to the voltage characteristics across the dummy element into the thermal resistance measurement results. Therefore, it is desirable to avoid using a dummy element to eliminate such errors. Furthermore, the above thermal resistance measurement method makes no mention of common-mode noise (hereinafter referred to as "switching noise") caused by the switching of the switching element of the test current source. Therefore, it is assumed that the above thermal resistance measurement method uses a linear power supply as the test current source. Switching power supplies generate switching noise, which makes it difficult to accurately measure thermal resistance, whereas linear power supplies do not generate switching noise. Linear power supplies primarily include a transformer that transforms the voltage of a commercial AC power supply and a rectifier that rectifies the transformed AC voltage. Since they do not contain switching elements, they do not generate switching noise. However, linear power supplies are larger than switching power supplies because they include a transformer that transforms commercial-frequency AC. Therefore, using a switching power supply as a heating power supply is desirable from the perspective of miniaturizing the heating power supply.

[0005] The present invention has been made to solve the above-mentioned problems, and aims to provide a transient thermal resistance measuring device and a transient thermal resistance measuring method that can reduce the switching noise of a heating power supply when measuring transient thermal resistance characteristics. [Means for solving the problem]

[0006] In order to achieve the above object, a transient thermal resistance measuring device according to an aspect of the present disclosure is a switching power supply having one or more switching elements, which generates a heating voltage by switching the one or more switching elements when it receives an operation command or an operation signal, and which stops the switching of the one or more switching elements to stop generating the heating voltage when it receives a forced stop signal, and which includes a heating power supply that supplies a direct current heating current to a semiconductor device under test for heating the semiconductor device under test, a measurement power supply unit that supplies a measurement current of a predetermined current value to the semiconductor device under test, a measurement unit that measures a voltage across the semiconductor device under test, and a control unit, wherein the heating power supply generates an operation control signal when it receives an operation signal converted from the operation command or the operation signal at an operation control terminal, and a microcontroller that generates a stop control signal by interrupt processing when the forced stop signal is input to the microcontroller; and a gate drive circuit that outputs an operation gate signal to the one or more switching elements based on the operation control signal from the microcontroller to switch the one or more switching elements for operation, and that outputs a stop gate signal to the one or more switching elements to stop switching of the one or more switching elements based on the stop control signal from the microcontroller, wherein a control unit of the control device sends the operation command to the heating power source or sends the operation signal to the operation control terminal of the microcontroller of the heating power source, and then, when a predetermined heating time has elapsed, inputs the forced stop signal to the external interrupt terminal of the microcontroller of the heating power source.

[0007] Furthermore, a transient thermal resistance measurement method according to another aspect of the present disclosure includes a heating power supply having one or more switching elements, which generates a heating voltage by switching the one or more switching elements when an operation command is received, and which stops the switching of the one or more switching elements to stop generation of the heating voltage when a forced stop signal is input, and which supplies a direct current heating current to a semiconductor device under test for heating the semiconductor device under test; a heating current switch which is provided in a flow path of the heating current from the positive terminal of the heating power supply through the semiconductor device under test to the negative terminal of the heating power supply, and which turns on the flow path of the heating current when an on signal is input and cuts off the flow path of the heating current when an off signal is input; a measurement power supply apparatus which supplies a measurement current of a predetermined current value to the semiconductor device under test; a measurement unit which measures a voltage across the semiconductor device under test; and a control unit, wherein the heating power supply receives an operation signal or a gate drive circuit that outputs an operation gate signal to the one or more switching elements to switch the one or more switching elements for operation based on the operation control signal from the microcontroller, and outputs a stop gate signal to the one or more switching elements to stop switching of the one or more switching elements based on the stop control signal from the microcontroller; a control unit of the control device that sends the operation command to the operation control terminal of the heating power supply and inputs the on signal to the heating current switch; and thereafter, when a predetermined heating time has elapsed, the control unit of the control device inputs the off signal to the heating current switch and inputs the forced stop signal to the external interrupt terminal of the heating power supply. [Effects of the Invention]

[0008] The present invention has an effect of providing a transient thermal resistance measuring device and a transient thermal resistance measuring method that can reduce switching noise of a heating power supply when measuring transient thermal resistance characteristics. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a functional block diagram showing an example of the configuration of a transient thermal resistance measuring device according to the first embodiment of the present disclosure. [Figure 2] FIG. 2 is a flowchart showing the control contents of the control unit of the control device of FIG. [Figure 3] FIG. 3 is a waveform diagram showing an example of a measured delay time between the output of a forced shutdown signal and the output of a forced shutdown gate signal in a transient thermal resistance measuring device. [Figure 4] FIG. 4 is a graph showing the dependency of the voltage across the semiconductor device under test on the junction temperature. [Figure 5] FIG. 5 is a graph showing the transition of the junction temperature of a semiconductor device under test measured according to a comparative example. [Figure 6] FIG. 6 is a graph showing the transient thermal resistance characteristics of a semiconductor device under test measured according to a comparative example. [Figure 7] FIG. 7 is a graph showing the transition of the junction temperature of the semiconductor device under test measured by the transient thermal resistance measurement apparatus of the first embodiment. [Figure 8] FIG. 8 is a graph showing the transient thermal resistance characteristics of a semiconductor device under test measured by the transient thermal resistance measurement apparatus of the first embodiment. [Figure 9] FIG. 9 is a functional block diagram showing an example of the configuration of a transient thermal resistance measurement device according to the second embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] (Points of focus of the inventors in this disclosure) When measuring transient thermal resistance characteristics, the point at which the supply of the heating current is stopped is the starting point of the time change in the transient thermal resistance characteristics, so it is necessary to identify the point at which the supply of the heating current is stopped. However, if the heating power supply is a switching power supply, it is generally shut down to perform various protection measures when it is stopped. As a result, it takes time for the switching power supply to actually stop after the stop operation, and the point at which the supply of the heating current is stopped cannot be known from the outside. Therefore, a heating current switch is provided in the heating current flow path, and the point at which an off signal is output to the heating current switch is treated as the point at which the supply of the heating current is stopped. In this case, even if a stop signal to the heating power supply and an off signal to the heating current switch are output simultaneously, the heating power supply stops after the heating current switch is turned off.

[0011] On the other hand, to measure transient thermal resistance characteristics precisely, it is necessary to accurately measure the transient thermal resistance characteristics over a very short period of time, up to 10 μs, from when the supply of heating current is stopped. However, when the heating power supply is a switching power supply, switching noise makes it impossible to accurately measure the transient thermal resistance characteristics during the 20 ms to 30 ms period from when the supply of heating current is stopped by turning off the heating current switch until the heating power supply is stopped.

[0012] Therefore, the inventors focused on clarifying the timing of stopping the supply of heating current and speeding up the stopping of the supply of heating current. After extensive research, they focused on forced stopping of switching elements, which are used exclusively in emergencies. When a forced stop signal is input to an external interrupt terminal, the microcontroller outputs a stop control signal to the gate drive circuit through interrupt processing. This allows the switching elements to be forcibly stopped, for example, within a few microseconds after the output of the forced stop signal. Therefore, by forcibly stopping the switching elements, the supply of heating current can be stopped more quickly. Furthermore, because the switching elements are stopped within a few microseconds after the output of the forced stop signal, the timing of stopping the supply of heating current can be identified based on the output timing of the forced stop signal, thereby making it possible to clarify the timing of stopping the supply of heating current.

[0013] In this way, the inventors came up with the idea of ​​forcibly stopping the switching element by outputting a forced stop signal to the external interrupt terminal of the microcontroller of the heating power supply in order to stop the supply of heating current.

[0014] With this configuration, for example, even if an off signal to the heating current switch and a forced stop signal to the heating power supply are output simultaneously, the stopping of the heating power supply is only slightly delayed relative to the turning off of the heating current switch, thereby reducing the switching noise of the heating power supply when measuring transient thermal resistance characteristics.

[0015] Furthermore, since the switching element can be forcibly stopped within a few microseconds after the output of the forced stop signal, the time when the supply of the heating current is stopped can be determined based on the time when the forced stop signal is output. For example, the time when the forced stop signal is output may be treated as the time when the supply of the heating current is stopped. Alternatively, for example, the time when a few microseconds (actual measured value) have elapsed since the output of the forced stop signal may be estimated as the time when the supply of the heating current is stopped. Alternatively, for example, if a stop gate signal is output following the output of the forced stop signal, the time when the stop gate signal is output may be treated as the time when the supply of the heating current is stopped.

[0016] As a result, the heating current switch can be omitted. In this case, the switching noise disappears at the same time as the switching element is forcibly stopped, so the switching noise of the heating power supply can be eliminated when measuring the transient thermal resistance characteristics.

[0017] The present disclosure has been made based on the above-described points of focus. The contents of the present disclosure will be described below.

[0018] A transient thermal resistance measuring device according to an aspect of the present disclosure is comprised of a switching power supply having one or more switching elements, which generates a heating voltage by switching the one or more switching elements when an operation command or an operation signal is received, and which stops the switching of the one or more switching elements to stop generating the heating voltage when a forced stop signal is input, and which includes a heating power supply that supplies a direct current heating current to a semiconductor device under test for heating the semiconductor device under test, a measurement power supply unit that supplies a measurement current of a predetermined current value to the semiconductor device under test, a measurement unit that measures a voltage across the semiconductor device under test, and a control unit, and the heating power supply generates an operation control signal when it receives an operation signal converted from the operation command or the operation signal at an operation control terminal, and outputs the forced stop signal to an external interrupt terminal. The device includes a microcontroller that generates a stop control signal by interrupt processing when a stop signal is input, and a gate drive circuit that outputs an operation gate signal to the one or more switching elements based on the operation control signal from the microcontroller to switch the one or more switching elements for operation, and outputs a stop gate signal to the one or more switching elements to stop switching of the one or more switching elements based on the stop control signal from the microcontroller, wherein a control unit of the control device sends the operation command to the heating power source or sends the operation signal to the operation control terminal of the microcontroller of the heating power source, and then, after a predetermined heating time has elapsed, inputs the forced stop signal to the external interrupt terminal of the microcontroller of the heating power source. Here, the "predetermined heating period" is determined appropriately taking into consideration the structure of the semiconductor device under test, the measurement conditions for transient thermal resistance characteristics, etc., and the "predetermined heating period" is determined to be a period of time sufficient for the temperature of the semiconductor device under test to saturate. Therefore, the starting point of the "predetermined heating period" may be determined appropriately after the control unit of the control device sends an operation command to the heating power supply or sends an operation signal to the operation control terminal of the microcontroller of the heating power supply.

[0019] According to this configuration, the measuring unit indirectly measures the transient thermal resistance of the semiconductor device under test by measuring the voltage across the semiconductor device under test. When the control unit of the control device sends an activation command to the heating power supply or an activation signal to the operation control terminal of the microcontroller of the heating power supply, the microcontroller in the heating power supply generates an activation signal converted from the activation command at the operation control terminal or an activation control signal in response to receiving the activation signal, causing the gate drive circuit to output an activation gate signal to one or more switching elements, which in turn generates a heating voltage. The heating voltage from the heating power supply then supplies a heating current to the semiconductor device under test through the heating current flow path, heating the semiconductor device under test.

[0020] After that, when a predetermined heating period has elapsed, the control unit of the control device inputs a forced stop signal to the external interrupt terminal of the microcontroller of the heating power supply. In response to the input of the forced stop signal to the external interrupt terminal, the microcontroller generates a stop control signal by interrupt processing, which causes the gate drive circuit to output a stop gate signal to one or more switching elements, thereby causing the one or more switching elements to stop switching (generating a heating voltage).

[0021] This allows the switching element to be forcibly stopped within, for example, several microseconds after the output of the forced stop signal, making it possible to identify the time when the supply of the heating current is stopped based on the time when the forced stop signal is output. For example, the time when the forced stop signal is output may be treated as the time when the supply of the heating current is stopped. Alternatively, for example, the time when several microseconds (actual measured value) have elapsed since the output of the forced stop signal may be estimated as the time when the supply of the heating current is stopped. Alternatively, for example, if a stop gate signal is output following the output of the forced stop signal, the time when the stop gate signal is output may be treated as the time when the supply of the heating current is stopped.

[0022] As a result, the starting point of the transient thermal resistance characteristic can be identified based on the output point of the forced shutdown signal. In addition, since the switching noise disappears simultaneously with the forced shutdown of the switching element, it is possible to provide a transient thermal resistance measuring device that can eliminate the switching noise of the heating power supply when measuring the transient thermal resistance characteristic (when measuring the voltage across the semiconductor device under test).

[0023] The transient thermal resistance measuring device may further include a heating current switch that is provided in the heating current path from the positive terminal of the heating power supply through the semiconductor device under test to the negative terminal of the heating power supply, and that turns on the heating current path when an on signal is input and cuts off the heating current path when an off signal is input, and the control unit of the control device may be a control unit that sends the operation command to the heating power supply or sends the operation signal to the operation control terminal of the microcontroller and inputs the on signal to the heating current switch, and then, after a predetermined heating time has elapsed, inputs the off signal to the heating current switch and inputs the forced stop signal to the external interrupt terminal of the microcontroller of the heating power supply. Here, "sending the operation command to the heating power supply or sending the operation signal to the operation control terminal of the microcontroller and inputting the on signal to the heating current switch" includes "sending the operation command to the heating power supply or sending the operation signal to the operation control terminal of the microcontroller, and then inputting the on signal to the heating current switch", "sending the operation command to the heating power supply or sending the operation signal to the operation control terminal of the microcontroller and inputting the on signal to the heating current switch simultaneously", and "inputting the on signal to the heating current switch, and then sending the operation command to the heating power supply or sending the operation signal to the operation control terminal of the microcontroller".

[0024] In this case, the timing of inputting an OFF signal to the heating current switch by the control device's control unit and the timing of inputting a forced stop signal to the external interrupt terminal of the heating power supply after the specified heating period has elapsed can be set arbitrarily. Therefore, by setting the timing of inputting an OFF signal to the heating current switch by the control device's control unit and the timing of inputting a forced stop signal to the external interrupt terminal of the heating power supply so as to minimize the delay in stopping the switching of the switching element in response to the cessation of the heating current supply (hereinafter simply referred to as "switching stop"), it is possible to reduce the switching noise of the heating power supply when measuring transient thermal resistance characteristics. Therefore, for example, if the measurement power supply device supplies a measurement current to the semiconductor device under test and the measurement unit of the control device starts measuring the voltage across the semiconductor device under test before the supply of the heating current is stopped, it is possible to measure transient thermal resistance characteristics with reduced switching noise.

[0025] The control unit may be a control unit that inputs the off signal to the heating current switch and the forced stop signal to the external interrupt terminal of the microcontroller of the heating power supply so that the heating power supply stops switching of the one or more switching elements after the heating current switch cuts off the flow path of the heating current.

[0026] According to this configuration, the switching of one or more switching elements of the heating power supply is stopped after the heating current switch cuts off the heating current flow path, so that the initial changes in the transient thermal resistance characteristics of the semiconductor device under test can be accurately measured, and in response to a stop signal from the control unit, the generation of switching noise by the heating power supply is stopped, for example, within a few μs from the output of the forced stop signal, so that the transient thermal resistance characteristics can be measured with reduced switching noise.

[0027] The control unit of the control device may be configured to simultaneously input the off signal to the heating current switch and the forced stop signal to the external interrupt terminal of the microcontroller of the heating power supply.

[0028] In this case, the microcontroller generates a stop control signal by interrupt processing in response to the input of a forced stop signal to the external interrupt terminal, so the response time for stopping switching in response to the input of the forced stop signal to the heating power supply is, for example, several μs. With this configuration, the input of an off signal to the heating current switch and the input of the forced stop signal to the external interrupt terminal of the heating power supply are performed simultaneously, so the delay in the timing of stopping switching relative to the timing of stopping the supply of heating current is, for example, several μs, and as a result, the switching noise of the heating power supply can be suitably reduced when measuring transient thermal resistance characteristics.

[0029] Furthermore, a transient thermal resistance measurement method according to another aspect of the present disclosure is provided, which includes a switching power supply having one or more switching elements, generating a heating voltage by switching the one or more switching elements when an operation command or an operation signal is received, and stopping the switching of the one or more switching elements to stop generation of the heating voltage when a forced stop signal is input, the switching power supply supplying a direct current heating current to a semiconductor device under test for heating the semiconductor device under test, a measurement power supply unit supplying a measurement current of a predetermined current value to the semiconductor device under test, a measurement unit measuring a voltage across the semiconductor device under test, and a control unit, wherein the heating power supply generates an operation control signal when it receives an operation signal converted from the operation command or the operation signal at an operation control terminal, and generates an operation control signal by interrupt processing when the forced stop signal is input to an external interrupt terminal. The present invention includes preparing a transient thermal resistance measuring device including a microcontroller that generates a stop control signal, and a gate drive circuit that outputs an operation gate signal to the one or more switching elements based on the operation control signal from the microcontroller, for switching the one or more switching elements for operation, and that outputs a stop gate signal to the one or more switching elements for stopping switching of the one or more switching elements based on the stop control signal from the microcontroller; sending the operation command to the heating power supply or sending the operation signal to the operation control terminal of the microcontroller of the heating power supply by a control unit of the control device; and then, when a predetermined heating time has elapsed, inputting the forced stop signal to the external interrupt terminal of the microcontroller of the heating power supply by the control unit of the control device.

[0030] With this configuration, the measurement unit indirectly measures the transient thermal resistance of the semiconductor device under test by measuring the voltage across the semiconductor device under test. The transient thermal resistance characteristics can then be measured based on the output point of the forced shutdown signal. Furthermore, since the switching noise disappears simultaneously with the forced shutdown of the switching element, a transient thermal resistance measurement method can be provided that can eliminate the switching noise of the heating power supply when measuring the transient thermal resistance characteristics.

[0031] The transient thermal resistance measuring device may further include a heating current switch that is provided in a heating current path that runs from the positive terminal of the heating power supply through the semiconductor device under test to the negative terminal of the heating power supply, the heating current switch conducting the heating current path when an ON signal is input and cutting off the heating current path when an OFF signal is input, and wherein sending the operation command to the heating power supply or sending the operation signal to the operation control terminal of the microcontroller of the heating power supply by the control unit of the control device may mean sending the operation command to the heating power supply or sending the operation signal to the operation control terminal of the microcontroller and inputting the ON signal to the heating current switch by the control unit of the control device, and then, after a predetermined heating time has elapsed, inputting the forced stop signal to the external interrupt terminal of the microcontroller of the heating power supply by the control unit of the control device may mean then, after the predetermined heating time has elapsed, inputting the OFF signal to the heating current switch and inputting the forced stop signal to the external interrupt terminal of the microcontroller of the heating power supply by the control unit of the control device.

[0032] According to this configuration, it is possible to accurately measure the initial change in the transient thermal resistance characteristic of the semiconductor device under test, and to measure the transient thermal resistance characteristic with reduced switching noise.

[0033] The control unit of the control device may send the operation command to the heating power supply or send the operation signal to the operation control terminal of the microcontroller and input the on signal to the heating current switch, and the control unit may also input the off signal to the heating current switch and the forced stop signal to the external interrupt terminal of the microcontroller of the heating power supply so that the heating power supply stops switching of the one or more switching elements after the heating current switch cuts off the flow path of the heating current.

[0034] This configuration makes it possible to measure transient thermal resistance characteristics with reduced switching noise.

[0035] The control unit of the control device may send the operation command to the heating power supply or send the operation signal to the operation control terminal of the microcontroller and input the on signal to the heating current switch, and the control unit may simultaneously input the off signal to the heating current switch and the forced stop signal to the external interrupt terminal of the microcontroller of the heating power supply.

[0036] This configuration makes it possible to suitably reduce the switching noise of the heating power source when measuring the transient thermal resistance characteristics.

[0037] Specific embodiments of the present disclosure will be described below with reference to the drawings. Note that, hereinafter, identical or corresponding elements throughout the drawings will be designated by the same reference numerals, and redundant descriptions thereof will be omitted. Furthermore, since the following drawings are for explaining the present disclosure, elements unrelated to the present disclosure may be omitted, dimensions may be inaccurate due to exaggeration or the like, or may be simplified, and the shapes of corresponding elements may not match in multiple drawings. Furthermore, the present disclosure is not limited to the following embodiments.

[0038] <Definition> In this specification and claims, "measuring transient thermal resistance characteristics" includes both "directly measuring transient thermal resistance characteristics" and "indirectly measuring transient thermal resistance characteristics." Therefore, measuring the voltage Vm across a semiconductor device under test while supplying a minute measurement current Im to the semiconductor device under test is nothing other than "measuring transient thermal resistance characteristics."

[0039] For convenience, the voltage across the semiconductor device under test (DUT) when only the measurement current Im is supplied is called the "voltage across Vm," and the voltage across the semiconductor device under test (DUT) when the heating current Ih (and the measurement current Im) are supplied is called the "forward voltage VF."

[0040] Ignoring the minute measurement current Im, the "heating current Ih" is essentially the forward current IF for heating the junction of the semiconductor device under test (DUT). Since the term "forward current IF" is usually used when calculating transient thermal resistance characteristics, the "heating current Ih" is sometimes called the "forward current IF" when calculating transient thermal resistance characteristics.

[0041] (Embodiment 1)

[0042] [composition] FIG. 1 is a functional block diagram showing an example of the configuration of a transient thermal resistance measurement apparatus 100 according to the first embodiment of the present disclosure.

[0043] Referring to FIG. 1, the transient thermal resistance measuring apparatus 100 includes a heating power supply 1, a heating current switch 2, a measurement power supply device 3, and a control device 4. The heating power supply 1 is connected to a semiconductor device under test (hereinafter sometimes referred to as DUT) 5 via the heating current switch 2 and wires W1 and W2. A reverse current blocking diode 6, for example, is provided along the wire W1. The measurement power supply device 3 is connected to the DUT 5 via wires W4 and W5. A reverse current blocking diode 7, for example, is provided along the wire W4. The control device 4 includes a measurement unit 41, which is connected to the DUT 5 via wires W6 and W7. These components will be described in detail below.

[0044] <dut5> The DUT 5 includes one or more semiconductor elements whose heat generation state is to be monitored. Examples of such semiconductor elements include diodes, MOSFETs, IGBTs, and bipolar transistors. In the first embodiment, the DUT 5 includes one diode as the semiconductor element whose heat generation state is to be monitored. In the first embodiment, the transient thermal resistance characteristics of the DUT 5 during its heat dissipation process are measured. To monitor the heat generation state of these semiconductor elements, the DUT 5 is heated by a heating current Ih (forward current IF), and then the heating current Ih is stopped. Then, a minute measurement current Im is supplied to the DUT 5 during its heat dissipation process, while measuring the voltage Vm across the DUT 5. This voltage Vm is converted to a junction temperature Tj based on its dependence on the junction temperature Tj, and then converted to a transient thermal resistance θth(jc). For heat dissipation, the DUT 5 is placed on, for example, a water-cooled heat sink.

[0045] {Junction temperature Tj of DUT5} The voltage Vm across the DUT5, which is the voltage drop due to the measurement current Im of the semiconductor element whose heat generation state is to be ascertained, includes the forward voltage of the diode, Vsd, which is the forward voltage of the body diode of the MOSFET, and the forward drop voltage of the pn junction such as the threshold voltage Vth of the MOSFET and IGBT, and the drop voltage of the channel (inversion layer) such as Vds, which is the drain-source voltage of the MOSFET, and Vce, which is the collector-emitter voltage of the IGBT. Therefore, hereinafter, for convenience, both the temperature obtained by converting the forward drop voltage of the pn junction into the temperature of the pn junction and the temperature obtained by converting the drop voltage of the channel (inversion layer) into the temperature of the channel (inversion layer) will be referred to as the "junction temperature Tj of the DUT5."

[0046] {Relationship to this disclosure} The heating power supply 1 and measurement power supply device 3 of the transient thermal resistance measuring device 100 of the present disclosure only serve to supply the heating current Ih and measurement current Im to the DUT 5, respectively, and therefore the present disclosure is not limited in any way by the form of the DUT 5.

[0047] <Heating power supply 1> The heating power supply 1 supplies a DC heating current Ih to the DUT 5 for heating the DUT 5. The heating power supply 1 is configured as a switching power supply and has one or more switching elements, and when an operation command or operation signal is received, the heating power supply 1 generates a heating voltage V4 by switching the one or more switching elements, and when a forced stop signal is input, the heating power supply 1 stops switching the one or more switching elements, thereby stopping the generation of the heating voltage V4. An example of a specific configuration of the heating power supply 1 having such functions will be described below.

[0048] The heating power supply 1 is configured as, for example, a switching power supply equipped with an inverter. Specifically, the heating power supply 1 includes, as main components of the switching power supply, a DC power supply 11, a DC / AC converter 12, a transformer 13, and a rectifier 14. The DC power supply 11 outputs a DC voltage V1. The DC power supply 11 is configured, for example, with a rectifier that rectifies AC power and a DC power generation device that generates DC power. The DC / AC converter 12 includes one or more switching elements and converts the DC voltage V1 from the DC power supply 11 into an AC voltage V2 in accordance with a gate signal Sg input from a gate drive circuit 16 (described later). Specifically, when an activation gate signal Sgo is input as the gate signal Sg, the DC / AC converter 12 switches on or off one or more switching elements to generate the AC voltage V2. On the other hand, when a stop gate signal Sgs is input as the gate signal Sg, the DC / AC converter 12 stops the one or more switching elements to stop generating the AC voltage V2. The DC / AC converter 12 is configured, for example, by a half-bridge or full-bridge inverter. The transformer 13 is configured, for example, by an insulating transformer. The transformer 13 transforms the AC voltage V2 from the DC / AC converter 12 and converts it into an AC voltage V3. The rectifier 14 rectifies the AC voltage V3 from the transformer 13 into a DC heating voltage V4. The output terminal of the rectifier 14 constitutes the output terminal of the heating power supply 1.

[0049] The heating power supply 1 further includes a controller 15 and a gate drive circuit 16 as a control section.

[0050] The controller 15 includes, for example, a communication unit 151 and a microcontroller 152. The communication unit 151 is configured with a communication interface such as a router, a modem, or an ONU. The communication unit 151 receives an operation command INSTo from a communication unit 43 of the control device 4 (described later), converts it into an operation signal So, and inputs it to an operation control terminal To of the microcontroller. The operation command INSTo is a command according to a predetermined protocol, and includes an activation command INSToo and a stop command INSTos. The operation signal So includes an activation signal Soo corresponding to the activation command INSToo and a stop signal Sos corresponding to the stop command INSTos.

[0051] The microcontroller 152 is composed of a CPU, ROM, RAM, I / O, etc., which are connected to each other via a data bus. In the microcontroller 152, the CPU processes data (information) input from an input port of the I / O using the RAM and ROM, and outputs the processed data (information) from an output port of the I / O. The microcontroller 152 has an operation control terminal To and an external interrupt terminal Tfs. The operation control terminal To and the external interrupt terminal Tfs are each composed of, for example, a predetermined input port of the I / O. An operation signal So from the communication unit 151 is input to the operation control terminal To, and a forced stop signal Sfs from the control unit 42 of the control device 4, which will be described later, is input to the external interrupt terminal Tfs. The operation signal So and the forced stop signal Sfs are voltage signals. Note that, instead of the operation signal So from the communication unit 151, the operation signal So from the control unit 42 of the control device 4 may be input to the operation control terminal To. The microcontroller 152 (more precisely, a CPU) outputs an operation control signal Co to the gate drive circuit 16 based on the operation signal So and the forced stop signal Sfs. Specifically, when an operation signal Soo is input as the operation signal So, the microcontroller 152 outputs an operation control signal Coo as the operation control signal Co that activates the switching elements of the DC / AC converter 12, and when a stop signal Sos is input as the operation signal So, the microcontroller 152 outputs a stop control signal Cos that stops the switching elements of the DC / AC converter 12 through normal processing. On the other hand, when a forced stop signal Sfs is input, the microcontroller 152 outputs the stop control signal Cos through interrupt processing. Furthermore, the microcontroller 152 controls the overall operation of the heating power source 1.

[0052] The important thing to note here is the following: The microcontroller 152 allocates a reasonable amount of time to process the numerous tasks required to control the overall operation of the heating power source 1. On the other hand, when the microcontroller 152 receives the forced stop signal Sfs, it uses interrupt processing to output the stop control signal Cos, prioritizing the numerous tasks required to control the overall operation of the heating power source 1. Therefore, when the microcontroller 152 receives the forced stop signal Sfs, it outputs the stop control signal Cos in the shortest possible time. According to an actual measurement example described below, the time required from the output of the forced stop signal Sfs to the output of the stop gate signal Sgs from the gate drive circuit 16 was 3.63 μs. In other words, the response time of the heating power source 1 in outputting the stop gate signal Sgs in response to the input of the forced stop signal Sfs is several μs.

[0053] In the first embodiment, the microcontroller 152 includes, for example, a pulse width modulation circuit (not shown). The microcontroller 152 generates an operation command in response to, for example, the operation signal So. The operation command includes an operation command in response to the operation signal Soo and a stop command in response to the stop signal Sos. The operation command is generated in response to input of the operation signal Soo or a set current value (target current value) of the heating current Ih (described later). The stop command is generated in response to input of the stop signal Sos or a forced stop signal Sfs. The pulse width modulation circuit outputs an operation control signal Coo, which is a PWM signal, in response to the operation command, and outputs a stop control signal Cos, which is also a PWM signal, in response to the stop command. The operation control signal Coo is, for example, a square wave voltage signal of 0V / 3.3V or 0V / 5V, and the stop control signal Cos is a voltage signal of 0V. The operation control signal Coo has a duty ratio in response to the set current value of the heating current Ih.

[0054] The gate drive circuit 16 is composed of a switching element and converts the operation control signal Co into a voltage signal at a gate voltage level that can turn on and off the switching elements of the DC / AC converter 12. The gate drive circuit 16 converts the operation control signal Coo into a square wave voltage signal of, for example, −5 V / +20 V, and converts the stop control signal Cos into a voltage signal of, for example, −5 V.

[0055] If the microcontroller 152 does not include a pulse-width modulation circuit, the gate drive circuit 16 also functions as the pulse-width modulation circuit. In this case, the microcontroller 152 outputs an operation control signal Co, which is an operation command. The operation control signal Co, which is an operation command, includes an operation control signal Coo, which is an activation command, and a stop control signal Cos, which is a stop command. The operation control signal Coo, which is an operation command, is a voltage signal having a voltage value corresponding to the set current value of the heating current Ih. The stop control signal Cos, which is a stop command, is a voltage signal having a voltage value of 0 V, for example. The gate drive circuit 16 converts the operation control signal Coo, which is an operation command, into an operation gate signal Sgo, which is a PWM signal of, for example, −5 V / +20 V, and converts the stop control signal Cos, which is a stop command, into a stop gate signal Sgs, which is a voltage signal of, for example, −5 V. The operation gate signal Sgo, which is a PWM signal, has a duty ratio corresponding to the set current value of the heating current Ih.

[0056] According to the above configuration, the heating voltage V4 is a voltage derived from the AC voltage V2 generated by the DC / AC converter 12 in response to the actuation gate signal Sgo, which corresponds to the set current value. Therefore, the heating power supply 1 is configured as a switching power supply and has one or more switching elements, and generates the heating voltage V4 by switching the one or more switching elements when it receives an actuation command INSToo or an actuation signal Soo, and stops the switching of the one or more switching elements to stop the generation of the heating voltage V4 when it inputs a forced stop signal Sfs.

[0057] The heating power supply 1 may also be configured as follows: A heating current sensor (not shown) is provided in the flow path (wires W1 and W2) of the heating current Ih, and a feedback control circuit (not shown) is provided in the microcontroller 152 before the pulse width modulation circuit. The feedback control circuit generates an operation amount by appropriately compensating for the error in the current value detected by the heating current sensor relative to the operation command (set current value), and outputs this operation amount to the pulse width modulation circuit as a corrected operation command. As a result, the heating current Ih is feedback-controlled to the operation command (set current value), and the heating power supply 1 operates as a constant current source.

[0058] Furthermore, a photocoupler (not shown) may be provided between the communication unit 151 and the microcontroller 152 to transmit the operation signal So while insulating the two from each other.

[0059] <Heating current switch 2> The heating current switch 2 is provided in a flow path of the heating current Ih that runs from the positive terminal of the heating power supply 1 through the DUT 5 to the negative terminal of the heating power supply 1, and when a first on signal Sc1on is input, the heating current switch 2 turns on the flow path of the heating current Ih, and when a first off signal Sc1off is input, the heating current switch 2 turns off the flow path of the heating current Ih. An example of a specific configuration of the heating current switch 2 that has this function will be described below.

[0060] The input terminal of the heating current switch 2 is connected to the output terminal of the heating power supply 1 (the output terminal of the rectifier 14). The positive output terminal of the heating current switch 2 is connected to the positive terminal of the DUT 5 via a wiring W1, and the negative output terminal of the heating current switch 2 is connected to the negative terminal of the DUT 5 via a wiring W2. The heating current switch 2 includes a diode 21, a switching element 22, and a gate drive circuit 23. The diode 21 is connected to the input terminal of the heating current switch 2 with its anode connected to the positive input terminal and its cathode connected to the negative input terminal. The switching element 22 is provided with a pair of main terminals connected between the positive input terminal and the positive output terminal of the heating current switch 2. The gate drive circuit 23 is composed of, for example, a binary signal generation circuit. The gate drive circuit 23 inputs a binary gate signal to the control terminal of the switching element 22 in accordance with a first control signal Sc1 input from a control unit 42 of the control device 4, which will be described later. Specifically, when a first on signal Sc1on is input as the first control signal Sc1, the gate drive circuit 23 inputs an on gate signal having either a high level or a low level and turning on the switching element 22 to the control terminal of the switching element 22. When a first off signal Sc1off is input as the first control signal Sc1, the gate drive circuit 23 inputs an off gate signal having the other of a high level or a low level and turning off the switching element 22 to the control terminal of the switching element 22. The switching element 22 is formed, for example, by an N-channel MOSFET. Note that the diode 21 may be omitted from the heating current switch 2.

[0061] With the above configuration, the heating current switch 2 conducts the flow path of the heating current Ih when the first switch-on signal Sc1on is input, and cuts off the flow path of the heating current Ih when the first switch-off signal Sc1off is input.

[0062] <Measurement power supply device 3> The measurement power supply 3 supplies the DUT 5 with a measurement current Im having a minute current value (e.g., 1 mA) as a set current value, which will be described later. The measurement power supply 3 is configured, for example, as a constant current source. The measurement power supply 3 operates when a second on signal Sc2on is input as the second control signal Sc2 from the control unit 42 of the control device 4, and stops when a second off signal Sc2off is input as the second control signal Sc2.

[0063] <Control device 4> The control device 4 includes a measurement unit 41 , a control unit 42 , and a communication unit 43 .

[0064] The measurement unit 41 includes a voltage sensor (not shown) that measures the voltage Vm or forward voltage VF across the DUT 5. Here, the voltage across the DUT 5 when the heating current Ih is being supplied is referred to as the forward voltage VF. The forward voltage VF is used to calculate the power P supplied to the DUT 5. Furthermore, the voltage across the DUT 5 (hereinafter sometimes simply referred to as the "voltage across the DUT 5") generated by the measurement current Im after the supply of the heating current Ih is stopped is referred to as the voltage across the DUT 5. The voltage across the DUT 5 is converted into the junction temperature Tj of the DUT 5. The power P and the junction temperature Tj are used to calculate the transient thermal resistance θth(jc).

[0065] Furthermore, in the present embodiment 1, the measurement unit 41 includes a calculation unit (not shown), which acquires the voltage Vm across both ends and the forward voltage VF as measurement data (time-series data) for calculating the transient thermal resistance characteristics of the DUT 5. Furthermore, the measurement unit 41 calculates the junction temperature transition (junction temperature time-series data) and the transient thermal resistance characteristics of the DUT 5 based on this measurement data in accordance with the user's operation of a user interface (not shown).

[0066] The control unit 42 is composed of a computing unit as described below, and sends an operation command INSToo to the heating power supply 1, or sends an operation signal Soo to the operation control terminal To of the microcontroller 152 of the heating power supply 1, and inputs a first on signal Sc1on to the heating current switch 2. After that, when a predetermined heating period has elapsed, it inputs a first off signal Sc1off to the heating current switch 2 and inputs a forced stop signal Sfs to the external interrupt terminal Tfs of the microcontroller 152 of the heating power supply 1. The "predetermined heating period" is determined appropriately taking into consideration the structure of the DUT 5, the measurement conditions for the transient thermal resistance characteristics, etc. The specific configuration of the control unit 42 having such functions will be described below.

[0067] In order to measure the transient thermal resistance characteristics of the DUT 5 in accordance with a predetermined procedure, the control unit 42 controls the start and stop of the heating power supply 1, the on / off of the heating current switch 2, the start and stop of the measurement power supply device 3, and the start and end of measurement of the forward voltage VF and the voltage Vm across the DUT 5 in the measurement unit 41. In addition, for example, the control unit 42 sets a target current value for the heating current Ih, a target current value for the measurement current Im, a "predetermined heating time," and a "predetermined measurement time."

[0068] {Settings} The control device 4 includes a user interface (not shown), and the control unit 42 includes a memory unit (not shown). The control unit 42 stores the setting items, such as the set current value (target current value) of the heating current Ih, the set current value (target current value) of the measurement current Im, the "predetermined heating time," and the "predetermined measurement time," in the memory unit in accordance with user operation of the user interface. These setting items are thus set. For example, the set current value of the heating current Ih is transmitted to the heating power source 1 as part of an operation command INSToo, or is transmitted to the heating power source 1 separately. For example, the set current value of the measurement current Im is transmitted to the measurement power source 3 as part of a second on signal Sc2on, or is transmitted to the measurement power source 3 separately. The set current values ​​of the heating current Ih and the measurement current Im are transmitted to the measurement unit 41. The "predetermined heating time" and the "predetermined measurement time" are used to control the heating current switch 2 and the measurement unit 41, respectively.

[0069] {Control of heating power supply 1 and heating current switch 2} In order to control the start and stop of the heating power source 1, the control unit 42 sends an operation command INSTo to the heating power source 1, or sends an activation signal Soo to the operation control terminal To of the microcontroller 152 of the heating power source 1, and outputs a forced stop signal Sfs. The operation signal Soo and the forced stop signal Sfs are output via an appropriate interface (for example, digital I / O). First, the configuration in which the control unit 42 sends the operation command INSTo to the heating power source 1 will be described below. The operation command INSTo includes an activation command INSToo and a stop command INSTos. When starting the heating power source 1, the control unit 42 sends the operation command INSTo as the operation command INSTo, and when stopping the heating power source 1 normally, it sends the stop command INSTos as the operation command INSTo. When forcibly stopping the heating power source 1, the control unit 42 outputs the forced stop signal Sfs.

[0070] Specifically, the control unit 42 first outputs an activation command INSToo as an operation command INSTo to the communication unit 43. This causes this activation command INSToo to be transmitted as an activation signal Soo to the operation control terminal To of the microcontroller 152 of the heating power source 1 via the communication unit 43 and the communication unit 151 of the heating power source 1. This causes the heating power source 1 to start generating a heating voltage V4. Furthermore, due to the generation of the heating voltage V4, a current corresponding to the heating voltage V4 flows through the diode 21 of the heating current switch 2.

[0071] Furthermore, the control unit 42 inputs a first on signal Sc1on as a first control signal Sc1 to the gate drive circuit 23 of the heating current switch 2. This turns on the switching element 22 of the heating current switch 2, thereby supplying the heating current Ih to the DUT 5, causing the DUT 5 to generate heat due to the heating current Ih.

[0072] The control unit 42 may output the operation command INSToo first or the first ON signal Sc1on (input to the gate drive circuit 23) first, or may output both at the same time. This is because, as will be described later, this does not affect the supply of the heating current Ih to the DUT 5.

[0073] Next, after a predetermined heating period has elapsed, the control unit 42 inputs a first off signal Sc1off as a first control signal Sc1 to the gate drive circuit 23 of the heating current switch 2. This turns off the switching element 22 of the heating current switch 2, stopping the supply of the heating current Ih to the DUT 5 and stopping heating of the DUT 5 by the heating current Ih. This causes the transient thermal resistance θth(jc) to begin changing due to heat dissipation from the DUT 5, making it possible to measure the transient thermal resistance characteristics of the DUT 5. In other words, measurement of the transient thermal resistance characteristics of the DUT 5 essentially begins. In this case, in the heating current switch 2, a current due to the heating voltage V4 still flows through the diode 21.

[0074] The control unit 42 also inputs a forced stop signal Sfs to the external interrupt terminal Tfs of the microcontroller 152 of the heating power supply 1. This causes the heating power supply 1 to stop switching of one or more switching elements in the shortest possible response time. This also eliminates switching noise in the heating power supply 1, and in the heating current switch 2, the current flowing through the diode 21 disappears.

[0075] The control unit 42 may output the first off signal Sc1off (input to the gate drive circuit 23) or the forced stop signal Sfs (input to the external interrupt terminal Tfs) in any order, or may output both simultaneously, for the following reasons.

[0076] The output of the first off signal Sc1off and the forced stop signal Sfs by the control unit 42 when starting measurement of the transient thermal resistance characteristic can be set arbitrarily. However, an absolute constraint in this case is that the stopping of switching in the heating power supply 1 must occur after the stopping of the supply of the heating current Ih. This is because the stopping of the supply of the heating current Ih initiates a change in the transient thermal resistance θth(jc) due to heat dissipation from the DUT 5, and if this is not done, it will be impossible to accurately measure the initial change in the transient thermal resistance characteristic of the DUT 5. Therefore, as long as the above-mentioned absolute constraint is satisfied, it does not matter whether the first off signal Sc1off or the forced stop signal Sfs is output first, or even if they are both output simultaneously.

[0077] In the first embodiment, the timing of inputting the first off signal Sc1off to the heating current switch 2 by the control unit 42 and the timing of inputting the forced stop signal Sfs to the external interrupt terminal Tfs of the microcontroller 152 of the heating power source 1 are set so as to minimize the delay in stopping switching when the supply of the heating current Ih is stopped, taking into consideration the response time of the heating current switch 2 to the input of the first off signal Sc1off and the response time of the heating power source 1 to the input of the forced stop signal Sfs. Specifically, in the first embodiment, the output of the first off signal Sc1off and the output of the forced stop signal Sfs are performed simultaneously, for example. In this case, the microcontroller 152 generates the stop control signal Cos by interrupt processing in response to the input of the forced stop signal Sfs to the external interrupt terminal Tfs, so that the response time of the heating power source 1 in stopping switching when the forced stop signal Sfs is input is minimized. As described above, the microcontroller 152 devotes a considerable amount of time to processing the numerous tasks required to control the overall operation of the heating power supply 1. However, when the forced stop signal Sfs is input, the microcontroller 152 outputs the stop control signal Cos through interrupt processing, prioritizing the numerous tasks required to control the overall operation of the heating power supply 1. This minimizes the delay in stopping switching relative to the cessation of the supply of the heating current Ih. According to an actual measurement example described below, the time required from the output of the forced stop signal Sfs until the output of the stop gate signal Sgs from the gate drive circuit 16 was 3.63 μs. As a result, the switching noise of the heating power supply 1 can be effectively reduced when measuring the transient thermal resistance characteristics (when measuring the voltage Vm across the heating power supply 1).

[0078] For example, a delay circuit that delays the transmission of the first off signal Sc1off may be provided in the transmission path of the first off signal Sc1off, the control unit 42 may be configured to output the forced stop signal Sfs after the output of the first off signal Sc1off, and the degree of delay of the delay circuit may be set so that the supply of the heating current Ih is stopped slightly before the stop of switching of the heating power supply 1. For example, a delay circuit that delays the transmission of the forced stop signal Sfs may be provided in the transmission path of the forced stop signal Sfs, the control unit 42 may be configured to output the forced stop signal Sfs before the output of the first off signal Sc1off, and the degree of delay of the delay circuit may be set so that the switching of the heating power supply 1 is stopped slightly after the stop of the supply of the heating current Ih.

[0079] In addition, the transient thermal resistance measuring device 100 may be configured so that the control unit 42 directly outputs an operation signal Soo to the operation control terminal To of the microcontroller 152 of the heating power supply 1 instead of outputting an operation command INSToo to the heating power supply 1.

[0080] When the control unit 42 normally stops the heating power source 1, it outputs a stop command INSTos as an operation command INSTo to the communication unit 43. As a result, this stop command INSTos is transmitted as a stop signal Sos to the operation control terminal To of the microcontroller 152 of the heating power source 1 via the communication unit 43 and the communication unit 151 of the heating power source 1. As a result, the heating power source 1 stops switching.

[0081] {Control of the measurement power supply device 3 and the measurement unit 41} The control unit 42 inputs a second on signal Sc2on as the second control signal Sc2 to the measurement power supply device 3 before the supply of the heating current Ih begins. The timing of inputting this second on signal Sc2on is not particularly limited, as long as it is before the supply of the heating current Ih begins. This causes the measurement power supply device 3 to supply a predetermined measurement current Im to the DUT 5. As a result, it becomes possible to measure the forward voltage VF and the voltage Vm across the DUT 5, which are used to calculate the transient thermal resistance characteristics. Furthermore, when a predetermined measurement time has elapsed since the supply of the heating current Ih was stopped, the control unit 42 inputs a second off signal Sc2off as the second control signal Sc2 to the measurement power supply device 3. This causes the measurement power supply device 3 to stop supplying the measurement current Im. The "predetermined measurement time" is determined appropriately taking into account the measurement conditions of the transient thermal resistance characteristics, etc.

[0082] Meanwhile, when the supply of the heating current Ih starts, the control unit 42 sends a third on signal Sc3on to the measurement unit 41 as a third control signal Sc3. This causes the measurement unit 41 to start measuring the voltage across the DUT 5. In this case, the voltage across the DUT 5 is the sum of the voltage drop due to the heating current Ih and the voltage drop due to the measurement current Im, and is denoted by the reference symbol VF. Then, when the supply of the heating current Ih is stopped, the voltage across the DUT 5 becomes equivalent to the voltage drop due only to the measurement current Im, and is denoted by the reference symbol Vm. The measurement of transient thermal resistance characteristics will be described in detail later.

[0083] Furthermore, when a predetermined measurement time has elapsed since the supply of the heating current Ih was stopped, the control unit 42 sends a third off signal Sc3off as the third control signal Sc3 to the measurement unit 41. This causes the measurement unit 41 to end measurement of the voltage Vm across the DUT 5.

[0084] The calculation unit and control unit 42 of the measurement unit 41 are configured, for example, by an arithmetic unit having a processor and a memory. A predetermined program for executing the functions of the calculation unit and control unit 42 of the measurement unit 41 is stored in the memory of this arithmetic unit, and the calculation unit and control unit 42 of the measurement unit 41 are realized as functional blocks by the processor reading and executing this predetermined program. In this case, this arithmetic unit operates as the calculation unit and control unit 42 of the measurement unit 41. This arithmetic unit can be configured, for example, by a computer, a personal computer, a microcontroller, an MPU, an FPGA (Field Programmable Gate Array), a PLC (Programmable Logic Controller), or the like. In the first embodiment, the calculation unit and control unit 42 of the measurement unit 41 are configured by a personal computer.

[0085] It should be noted that the functions of the elements disclosed herein can be performed using circuits or processing circuits, including general-purpose processors, special-purpose processors, integrated circuits, ASICs (Application Specific Integrated Circuits), conventional circuits, and / or combinations thereof, configured or programmed to perform the disclosed functions. A processor is considered a processing circuit or circuit because it includes transistors and other circuitry. In this disclosure, a "circuit" or "unit" is hardware that performs the recited functions or hardware that is programmed to perform the recited functions. The hardware may be hardware disclosed herein or other known hardware that is programmed or configured to perform the recited functions. Where hardware is a processor, which is considered a type of circuit, the "circuit" or "unit" is a combination of hardware and software, and software is used to configure the hardware and / or processor.

[0086] The communication unit 43 converts the operation command INSTo sent from the control unit 42 into data for communication and sends it out. The communication unit 151 is configured with a communication interface such as a router, a modem, or an ONU, for example.

[0087] [Operation] Next, the operation of the transient thermal resistance measuring device 100 configured as above (transient thermal resistance measuring method) will be described with reference to Figures 1 and 2. These operations are performed by the control unit 42 controlling the transient thermal resistance measuring device 100. Figure 2 is a flowchart showing the control contents of the control unit 42 of the control device 4 of Figure 1.

[0088] 1 and 2, first, the control unit 42 causes the heating power supply 1 to start operating and causes the measurement power supply device 3 to start supplying the measurement current Im (step S1). Specifically, the control unit 42 sends an operation command INSToo. This operation command INSToo is then transmitted as an operation signal Soo to the operation control terminal To of the microcontroller 152 via the communication unit 43 and the communication unit 151 of the heating power supply 1. The microcontroller 152 then generates an operation control signal Coo in response to receiving the operation signal Soo at the operation control terminal To, which causes the gate drive circuit 16 to output an operation gate signal Sgo to the DC / AC converter 12 (one or more switching elements). The DC / AC converter 12 then generates an AC voltage V2, which generates a heating voltage V4.

[0089] The control unit 42 also inputs a second on signal Sc2on to the measurement power supply device 3. This causes the measurement power supply device 3 to supply a predetermined measurement current Im to the DUT 5.

[0090] Next, the control unit 42 causes the heating current switch 2 to start supplying the heating current Ih (forward current IF), and causes the measurement unit 41 to start measuring the forward voltage VF of the DUT 5 (step S2). Specifically, the control unit 42 inputs a first on signal Sc1on to the gate drive circuit 23 of the heating current switch 2. The gate drive circuit 23 then turns on the switching element 22, causing the heating current switch 2 to conduct the flow path of the heating current Ih. As a result, the heating current Ih is supplied to the DUT 5 through the flow path of the heating current Ih by the heating voltage V4 of the heating power supply 1, and the DUT 5 is heated by the heating current Ih.

[0091] Furthermore, the control unit 42 sends a third on signal Sc3on to the measurement unit 41. This causes the measurement unit 41 to start measuring the forward voltage VF of the DUT5.

[0092] Next, after the predetermined heating period has elapsed, the control unit 42 stops the supply of the heating current Ih to the heating current switch 2 and stops the heating power supply 1 (step S3). The "predetermined heating period" is determined appropriately taking into consideration the structure of the DUT 5, the measurement conditions for the transient thermal resistance characteristics, and the like. The "predetermined heating period" is also determined to be a time sufficient for the temperature of the DUT 5 to saturate. Therefore, the start point of the "predetermined heating period" may be determined appropriately as long as it is after the control unit 42 sends an operation command INSToo to the heating power supply 1 or sends an operation signal Soo to the operation control terminal To of the microcontroller 152 of the heating power supply 1. Here, the start point of the "predetermined heating period" is set, for example, to the time when the first on signal Sc1on is output to the gate drive circuit 23 of the heating current switch 2.

[0093] Specifically, when a predetermined heating period has elapsed, the control unit 42 inputs a first off signal Sc1off to the gate drive circuit 23 of the heating current switch 2. The gate drive circuit 23 then turns off the switching element 22, causing the heating current switch 2 to interrupt the flow path of the heating current Ih. This stops the supply of the heating current Ih to the DUT 5.

[0094] Furthermore, the control unit 42 inputs a forced stop signal Sfs to the external interrupt terminal Tfs of the microcontroller 152 of the heating power supply 1 simultaneously with input of the first off signal Sc1off to the gate drive circuit 23. Then, in response to the input of the forced stop signal Sfs to the external interrupt terminal Tfs, the microcontroller 152 generates a stop control signal Cos through interrupt processing, which causes the gate drive circuit 16 to output a stop gate signal Sgs to the DC / AC converter 12 (one or more switching elements). This causes the DC / AC converter 12 to stop switching. As a result, the generation of switching noise by the heating power supply 1 is stopped in the shortest possible response time in response to the output of the stop signal (forced stop signal Sfs) by the control unit 42 of the control device 4. As described above, the microcontroller 152 devotes a considerable amount of time to processing the numerous tasks required to control the overall operation of the heating power supply 1. However, when the forced stop signal Sfs is input, the microcontroller 152 outputs the stop control signal Cos through interrupt processing, prioritizing the numerous tasks for controlling the overall operation of the heating power supply 1.

[0095] When the supply of the heating current Ih is stopped, a voltage drop occurs across the DUT 5 due to only the measurement current Im, and the measurement unit 41 of the control device 4 begins to measure this voltage drop as the voltage Vm across the DUT 5 (step S4). This allows the measurement of the voltage Vm across the DUT 5 to be performed in a state where the generation of switching noise by the heating power supply 1 is stopped in the shortest possible response time. As a result, the superposition of the switching noise from the heating power supply 1 on the transient thermal resistance characteristics is suppressed, and the transient thermal resistance characteristics of the DUT 5 are accurately measured.

[0096] Next, when a predetermined measurement time has elapsed since the supply of the heating current Ih was stopped, the control unit 42 causes the measurement unit 41 to acquire measurement data (step S5). Specifically, the control unit 42 sends a third off signal Sc3off to the measurement unit 41. This causes the measurement unit 41 to stop measuring the voltage Vm across the DUT 5 and create a data file of the forward voltage VF, the voltage Vm across the DUT 5, the heating current Ih (forward current IF) (set current value), and the measurement current Im (set current value). The control unit 42 also inputs a second off signal Sc2off to the measurement power supply device 3. This causes the measurement power supply device 3 to stop supplying the measurement current Im. Note that the order in which the measurement of the voltage Vm across the DUT 5 and the supply of the measurement current Im are stopped is not particularly limited. The measurement unit 41 then calculates the transient thermal resistance characteristics of the DUT 5 based on this data file, in accordance with the user's operation of the user interface. A specific procedure for calculating the transient thermal resistance characteristics will be described later.

[0097] Thus, the control of the transient thermal resistance measuring apparatus 100 by the control unit 42 ends.

[0098] [Action and effect] The effects of the transient thermal resistance measuring apparatus 100 of the first embodiment will be described below in order.

[0099] <Response time of heating power supply 1> Figure 3 is a waveform diagram showing an example of a measured delay time between the output of the forced stop signal Sfs and the output of the stop gate signal Sgs in the transient thermal resistance measurement device 100. Figure 3 was created by tracing image data showing the measurement results of the measurement device. In Figure 3, the horizontal axis represents time and the vertical axis represents signal level. The upper line represents the waveform of the forced stop signal Sfs, and the lower line represents the waveform of the stop gate signal Sgs. Referring to Figure 3, the time when the forced stop signal Sfs transitions from low level to high level represents the output time of the forced stop signal Sfs. The time when the stop gate signal Sgs transitions from high level to low level represents the output time of the stop gate signal Sgs. In this measurement example, the delay time between the output of the forced stop signal Sfs and the output of the stop gate signal Sgs was 3.63 μs. To accurately measure transient thermal resistance characteristics, it is necessary to stop the generation of switching noise from the heating power supply 1 within 10 μs after interrupting the flow path of the heating current Ih. Therefore, the delay time of 3.63 μs between the output of the forced stop signal Sfs and the output of the stop gate signal Sgs is evaluated to be within the allowable range.

[0100] Because the input of the first off signal Sc1off to the gate drive circuit 23 of the heating current switch 2 and the input of the forced stop signal Sfs to the external interrupt terminal Tfs of the microcontroller 152 of the heating power supply 1 are performed simultaneously, this measurement example demonstrated that the generation of switching noise by the heating power supply 1 stops within approximately 4 μs after the flow path of the heating current Ih is cut off. As a result, it was confirmed that the transient thermal resistance measuring device 100 suppresses the superposition of the switching noise by the heating power supply 1 on the transient thermal resistance characteristics, making it possible to accurately measure the transient thermal resistance characteristics of the DUT 5.

[0101] <Example> An example was carried out to confirm the effects of the transient thermal resistance measuring device 100 of the first embodiment. The example is the transient thermal resistance measuring device 100 described above. A comparative example was also carried out to contrast with the example. In the comparative example, when the control unit 42 starts measuring the transient thermal resistance characteristics, it outputs a first off signal Sc1off to the heating current switch 2 and simultaneously sends a stop command INSTos for normal stop to the heating power supply 1. By sending this stop command INSTos, the heating power supply 1 stops switching the switching element of the DC / AC converter 12 approximately 30 ms after the supply of the heating current Ih is stopped. The other configurations of the comparative example are the same as those of the example.

[0102] {Transient thermal resistance characteristic measurement procedure} Before describing the results of the examples and comparative examples, we will first briefly explain the procedure for measuring the transient thermal resistance characteristics. Note that the measurement of the transient thermal resistance θth(jc) is specified, for example, in the standard JEDEC51-14 (JESD51-14).

[0103] First, the change characteristic of the voltage Vm across the DUT 5 with respect to the junction temperature Tj (hereinafter, may be simply referred to as "junction temperature") of the DUT 5 is measured (hereinafter, may be referred to as the dependency of the voltage Vm across the DUT 5 on the junction temperature Tj). This measurement is performed, for example, by placing the DUT 5 in a thermostatic chamber and changing the temperature while supplying a measurement current Im to the DUT 5 to change the voltage Vm across the DUT 5.

[0104] 4 is a graph showing the dependency of the voltage Vm across the DUT on the junction temperature Tj. Referring to FIG. 4, the voltage Vm across the DUT 5 decreases almost linearly as the junction temperature Tj increases.

[0105] Next, the voltage Vm across the DUT 5 is measured while changing the junction temperature Tj of the DUT 5. In this embodiment, the voltage Vm across the DUT 5 is measured while lowering the junction temperature Tj of the DUT 5 by heat dissipation through cooling using a water-cooled heat sink. To achieve this, the DUT 5 is first heated by a forward current IF (heating current Ih) for a "predetermined heating time." This heats the DUT 5 so that the temperature of its junction reaches a saturated state. Furthermore, the forward voltage (voltage across) VF of the DUT 5 is measured during the "predetermined heating time." After the "predetermined heating time" has elapsed, heating of the DUT 5 is stopped. Then, from the point at which the heating is stopped, the voltage Vm across the DUT 5 is measured while the DUT 5 is cooled by the heat sink.

[0106] Next, using the above-mentioned dependency of the voltage Vm across the DUT 5 on the junction temperature Tj, the measured time-series data of the voltage Vm across the DUT 5 is converted into the junction temperature Tj of the time-series data of the DUT 5. In this case, since the voltage Vm across the DUT 5 immediately after the supply of the forward current IF (heating current Ih) is stopped cannot be accurately measured due to the recovery characteristics of the DUT 5, the junction temperature Tj(0) at the time the supply of the forward current IF (heating current Ih) is stopped is estimated.

[0107] Next, the transient thermal resistance characteristics of the time-series data are calculated by dividing the junction temperature change (Tj(0)-Tj(t)) obtained by subtracting the junction temperature Tj of the time-series data of DUT5 from this junction temperature Tj(0) by the power P required to heat DUT5. The power P required to heat DUT5 is calculated by integrating the heating current Ih (set current value) x forward voltage VF at every moment during the "predetermined heating time."

[0108] Through the above measurements and calculations, the transient thermal resistance characteristics of the DUT 5 are measured.

[0109] {Implementation results} Fig. 5 is a graph showing the transition of junction temperature of DUT 5 measured by a comparative example. Fig. 6 is a graph showing the transient thermal resistance characteristics of DUT 5 measured by a comparative example. Fig. 7 is a graph showing the transition of junction temperature of DUT 5 measured by an example (transient thermal resistance measuring apparatus 100 of embodiment 1). Fig. 8 is a graph showing the transient thermal resistance characteristics of DUT 5 measured by an example.

[0110] In Figures 5 and 7, the horizontal axis represents time t (sec) on a logarithmic scale, and the vertical axis represents junction temperature Tj (°C). In Figures 6 and 8, the horizontal axis represents time t (sec) on a logarithmic scale, and the vertical axis represents transient thermal resistance θth(jc) (°C / W) on a logarithmic scale. Note that the transient thermal resistance θth(jc) (°C / W) in this example and comparative example includes contact thermal resistance. Note that the sampling period for measurement data of junction temperature Tj and transient thermal resistance θth(jc) is 2 μs until time 1.E-01 and 2 ms thereafter. Therefore, the change curves of junction temperature Tj and transient thermal resistance θth(jc) show significant fluctuations until time 1.E-01, but the fluctuations become smaller after time 1.E-01.

[0111] 5, in the comparative example, the junction temperature Tj fluctuates in a very short cycle from approximately time 2.E-05 to 3.E-02. The amplitude of this fluctuation was approximately ±0.23°C (equivalent to approximately ±0.39 mV in voltage) in the area indicated by the dotted ellipse. This fluctuation is presumed to be caused by superimposed switching noise.

[0112] 6, in the comparative example, the transient thermal resistance θth(jc) fluctuates in a very short cycle in response to the junction temperature Tj, approximately between times 2.E-05 and 3.E-02. The amplitude of this fluctuation was approximately ±0.0043°C / W in the region indicated by the dotted ellipse. This fluctuation corresponds to the fluctuation of the junction temperature Tj, and is presumed to be caused by superimposed switching noise.

[0113] Referring to Figure 7, in the example, the junction temperature Tj barely fluctuates, with only slight, minute periodic fluctuations being observed. The amplitude of this slight, minute periodic fluctuation was approximately ±0.07°C (approximately ±0.11mV in voltage terms) in the region indicated by the dotted ellipse. Therefore, it is determined that no switching noise is superimposed on the junction temperature Tj. It is assumed that this fluctuation is caused by the superposition of ordinary miscellaneous noise.

[0114] Referring to Figure 8, in the example, the transient thermal resistance θth(jc) hardly fluctuates, with only slight, minute periodic fluctuations being observed. The amplitude of this slight, minute periodic fluctuation was approximately ±0.001°C / W in the area indicated by the dotted ellipse. Therefore, it is determined that no switching noise is superimposed on the transient thermal resistance θth(jc). It is assumed that this fluctuation is caused by the superposition of ordinary miscellaneous noise.

[0115] Therefore, this example demonstrates that the transient thermal resistance measuring device 100 of the first embodiment can reduce the switching noise of the heating power source 1 when measuring the transient thermal resistance characteristics.

[0116] {summary} According to the transient thermal resistance measuring device 100 of the first embodiment, the measuring unit 41 of the control device 4 measures the voltage Vm across the DUT 5 to indirectly measure the transient thermal resistance θth(jc) of the DUT 5. Then, since the switching of one or more switching elements of the heating power supply is stopped after the heating current switch 2 cuts off the flow path of the heating current Ih, it is possible to accurately measure the initial change in the transient thermal resistance characteristic of the DUT 5. Furthermore, since the generation of switching noise by the heating power supply 1 is stopped, for example, several μs after the output of the forced stop signal Sfs in response to the stop signal from the control unit 42, it is possible to measure the transient thermal resistance characteristic with reduced switching noise.

[0117] (Embodiment 2) FIG. 9 is a functional block diagram showing an example of the configuration of a transient thermal resistance measurement apparatus 200 according to the second embodiment of the present disclosure.

[0118] [composition] Referring to FIG. 9, the configuration of the transient thermal resistance measuring device 200 of the second embodiment is the same as the configuration of the transient thermal resistance measuring device 100 of the first embodiment except that the heating current switch 2 of FIG. 1 is omitted.

[0119] [Operation] Next, the operation of the transient thermal resistance measuring apparatus 200 configured as above (transient thermal resistance measuring method) will be described with reference to FIG.

[0120] First, the control unit 42 starts supplying a heating current Ih (forward current IF) to the heating power supply 1. Specifically, the control unit 42 sends an activation command INSToo. This activation command INSToo is then transmitted as an activation signal Soo to the operation control terminal To of the microcontroller 152 via the communication unit 43 and the communication unit 151 of the heating power supply 1. The microcontroller 152 then generates an activation control signal Coo in response to receiving the activation signal Soo at the operation control terminal To, which causes the gate drive circuit 16 to output an activation gate signal Sgo to the DC / AC converter 12 (one or more switching elements). This causes the DC / AC converter 12 to generate an AC voltage V2, which in turn generates a heating voltage V4. The heating current Ih is supplied to the DUT 5 through the flow path of the heating current Ih by this heating voltage V4, and the DUT 5 is heated by the heating current Ih.

[0121] Furthermore, the control unit 42 causes the measurement unit 41 to start measuring the forward voltage VF of the DUT 5. Specifically, the control unit 42 sends a third on signal Sc3on to the measurement unit 41. This causes the measurement unit 41 to start measuring the forward voltage VF of the DUT 5.

[0122] Next, when a predetermined heating period has elapsed, the control unit 42 stops the supply of the heating current Ih to the heating power supply 1. Specifically, when the predetermined heating period has elapsed, the control unit 42 inputs a forced stop signal Sfs to the external interrupt terminal Tfs of the microcontroller 152 of the heating power supply 1. Then, in response to the input of the forced stop signal Sfs to the external interrupt terminal Tfs, the microcontroller 152 generates a stop control signal Cos by interrupt processing, which causes the gate drive circuit 16 to output a stop gate signal Sgs to the DC / AC converter 12. Then, the DC / AC converter 12 stops switching. This stops the supply of the heating current Ih to the DUT 5. Furthermore, the generation of switching noise by the heating power supply 1 is stopped.

[0123] When the supply of the heating current Ih is stopped, a voltage drop occurs across the DUT 5 due to only the measurement current Im, and the measurement unit 41 of the control device 4 begins to measure this voltage drop as the voltage Vm across the DUT 5. This allows the measurement of the voltage Vm across the DUT 5 to be performed in the absence of switching noise from the heating power supply 1. As a result, the superposition of the switching noise from the heating power supply 1 on the transient thermal resistance characteristics is eliminated, and the transient thermal resistance characteristics of the DUT 5 can be accurately measured.

[0124] The subsequent operations are the same as those of the transient thermal resistance measuring apparatus 100 of the first embodiment, and therefore will not be described again.

[0125] According to the transient thermal resistance measuring device 200 of the second embodiment, the measuring unit 41 of the control device 4 measures the voltage Vm across the DUT 5 to indirectly measure the transient thermal resistance θth(jc)θ of the DUT 5. The transient thermal resistance characteristics can then be measured based on the output point of the forced shutdown signal Sfs. Furthermore, since switching noise disappears simultaneously with the forced shutdown of the switching element of the heating power supply 1, it is possible to provide a transient thermal resistance measuring device that can eliminate the switching noise of the heating power supply 1 when measuring the transient thermal resistance characteristics. Furthermore, the heating current switch can be omitted.

[0126] Many modifications and alternative embodiments will be apparent to those skilled in the art in light of the above description, and therefore the above description should be construed as illustrative only. [Industrial Applicability]

[0127] The transient thermal resistance measuring device and transient thermal resistance measuring method of the present invention are useful as a transient thermal resistance measuring device and transient thermal resistance measuring method that can reduce switching noise when measuring the transient thermal resistance characteristics of a heating power supply composed of a switching power supply. [Explanation of symbols]

[0128] 1 Heating power supply 2 Heating current switch 3 Measurement power supply 4. Control device 5. Semiconductor device under test (DUT) 6,7 Reverse current blocking diode 11 DC power supply 12 DC / AC converter 13. Transformer 14 Rectifier 15 Controller 16 Gate drive circuit 21 Diode 22 Switching element 23 Gate drive circuit 41 Measuring part 42 Control Unit 43 Communications Department 100 Transient thermal resistance measuring device 151 Communications Department 152 microcontrollers Co Operation control signal IF forward current Ih heating current Im measurement current INSTo Driving Instructions Sc1 to Sc3: First to third control signals Sfs forced stop signal Sg Gate signal So driving signal To Operation Control Terminal Tfs external interrupt pin V4 Heating voltage VF forward voltage Vm Voltage across both ends

Claims

1. a heating power supply having one or more switching elements, which generates a heating voltage by switching the one or more switching elements when an operation command or an operation signal is received, and which stops the switching of the one or more switching elements and stops the generation of the heating voltage when a forced stop signal is input, and which supplies a direct current heating current to the semiconductor device under test for heating the semiconductor device under test; a measurement power supply unit that supplies a measurement current having a predetermined current value to the semiconductor device under test; a control device having a measurement unit that measures a voltage across both ends of the semiconductor device under test, and a control unit; the heating power supply includes a microcontroller that generates an operation control signal when an operation signal converted from the operation command or the operation signal is received at an operation control terminal, and generates a stop control signal by interrupt processing when the forced stop signal is input to an external interrupt terminal; and a gate drive circuit that outputs an operation gate signal to the one or more switching elements based on the operation control signal from the microcontroller, for switching the one or more switching elements for operation, and outputs a stop gate signal to the one or more switching elements based on the stop control signal from the microcontroller, for stopping switching of the one or more switching elements, A transient thermal resistance measuring device, wherein the control unit of the control device sends the operation command to the heating power source or sends the operation signal to the operation control terminal of the microcontroller of the heating power source, and then, when a predetermined heating time has elapsed, inputs the forced stop signal to the external interrupt terminal of the microcontroller of the heating power source.

2. the transient thermal resistance measuring apparatus further comprises a heating current switch that is provided in a flow path of the heating current from the positive terminal of the heating power source through the semiconductor device under test to the negative terminal of the heating power source, the heating current switch conducting the flow path of the heating current when an ON signal is input, and cutting off the flow path of the heating current when an OFF signal is input, 2. The transient thermal resistance measuring device of claim 1, wherein the control unit of the control device sends the operation command to the heating power supply or sends the operation signal to the operation control terminal of the microcontroller and inputs the on signal to the heating current switch, and then, when a predetermined heating time has elapsed, inputs the off signal to the heating current switch and inputs the forced stop signal to the external interrupt terminal of the microcontroller of the heating power supply.

3. 3. The transient thermal resistance measuring device of claim 2, wherein the control unit inputs the off signal to the heating current switch and the forced stop signal to the external interrupt terminal of the microcontroller of the heating power supply so that the heating power supply stops switching of the one or more switching elements after the heating current switch interrupts the flow path of the heating current.

4. 4. The transient thermal resistance measuring device according to claim 2, wherein the control unit simultaneously inputs the off signal to the heating current switch and the forced stop signal to the external interrupt terminal of the microcontroller of the heating power supply.

5. a control device including a heating power supply having one or more switching elements, the heating power supply being configured to generate a heating voltage by switching the one or more switching elements when an operation command or an operation signal is received, and to stop generating the heating voltage by stopping the switching of the one or more switching elements when a forced stop signal is input, the heating power supply supplying a direct current heating current to the semiconductor device under test for heating the semiconductor device under test; a measurement power supply device supplying a measurement current of a predetermined current value to the semiconductor device under test; a measurement unit measuring a voltage across the semiconductor device under test; and a control unit, the heating power supply including a microcontroller that generates an operation control signal when an operation signal converted from the operation command or the operation signal is received at an operation control terminal, and that generates a stop control signal by interrupt processing when the forced stop signal is input to an external interrupt terminal; and a gate drive circuit that outputs an operation gate signal to the one or more switching elements based on the operation control signal from the microcontroller, causing the one or more switching elements to switch for operation, and that outputs a stop gate signal to the one or more switching elements to stop switching of the one or more switching elements based on the stop control signal from the microcontroller; Sending the operation command to the heating power source or sending the operation signal to the operation control terminal of the microcontroller of the heating power source by a control unit of the control device; Thereafter, when a predetermined heating time has elapsed, the control unit of the control device inputs the forced stop signal to the external interrupt terminal of the microcontroller of the heating power supply.

6. the transient thermal resistance measuring apparatus further comprises a heating current switch that is provided in a flow path of the heating current from the positive terminal of the heating power source through the semiconductor device under test to the negative terminal of the heating power source, the heating current switch conducting the flow path of the heating current when an ON signal is input, and cutting off the flow path of the heating current when an OFF signal is input, sending the operation command to the heating power source or sending the operation signal to the operation control terminal of the microcontroller of the heating power source by the control unit of the control device means sending the operation command to the heating power source or sending the operation signal to the operation control terminal of the microcontroller and inputting the ON signal to the heating current switch by the control unit of the control device; 6. The transient thermal resistance measuring method according to claim 5, wherein, after a predetermined heating time has elapsed, the control unit of the control device inputs the forced stop signal to the external interrupt terminal of the microcontroller of the heating power supply, and, after a predetermined heating time has elapsed, the control unit of the control device inputs the off signal to the heating current switch and the forced stop signal to the external interrupt terminal of the microcontroller of the heating power supply.

7. 7. The transient thermal resistance measuring method of claim 6, wherein the control unit of the control device sends the operation command to the heating power supply or sends the operation signal to the operation control terminal of the microcontroller and inputs the on signal to the heating current switch, and the control unit inputs the off signal to the heating current switch and the forced stop signal to the external interrupt terminal of the microcontroller of the heating power supply so that the heating power supply stops switching of the one or more switching elements after the heating current switch interrupts the flow path of the heating current.

8. 8. The transient thermal resistance measuring method according to claim 6 or 7, wherein the control unit of the control device sends the operation command to the heating power supply or sends the operation signal to the operation control terminal of the microcontroller and inputs the on signal to the heating current switch by the control unit, and the control unit simultaneously inputs the off signal to the heating current switch and the forced stop signal to the external interrupt terminal of the microcontroller of the heating power supply.

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