JP2021042967A - Thermal resistance measurement method - Google Patents

Abstract

To measure thermal resistance between a plurality of elements.SOLUTION: A thermal resistance measurement method includes: a step (S3) of applying a predetermined measurement current to a measurement object element; steps (S4-S6) of heating a heating object element over a predetermined heating period; a step (S5) of calculating a heat generation amount of the heating object element; a step (S7) of measuring an inter-terminal voltage of the measurement object element over a predetermined measurement period; a step (S8) of calculating a temperature change amount of the measurement object element from a change amount of the inter-terminal voltage and a temperature coefficient under a measurement current applying condition; and a step (S9) of calculating thermal resistance between the measurement object element and the heating object element from the temperature change amount of the measurement object element and the heat generation amount of the heating object element.SELECTED DRAWING: Figure 3

Description

The invention disclosed herein relates to a method for measuring thermal resistance between a plurality of elements.

Conventionally, various methods for measuring the thermal resistance of semiconductor elements have been proposed (see, for example, Patent Documents 1 to 3).

JP-A-2019-52855 Japanese Unexamined Patent Publication No. 2017-135868 Japanese Unexamined Patent Publication No. 2015-81786

However, all of the above-mentioned conventional thermal resistance measuring methods target the thermal resistance of a single semiconductor element (= thermal resistance due to self-heating), and cannot measure the thermal resistance between a plurality of elements. ..

An object of the invention disclosed in the present specification is to provide a thermal resistance measuring method capable of measuring a thermal resistance between a plurality of elements in view of the above-mentioned problems found by the inventor of the present application.

The thermal resistance measuring method disclosed in the present specification includes a step of energizing a measurement target element with a predetermined measurement current, a step of heating the heating target element over a predetermined heating period, and a step of heating the heating target element. The measurement is performed from the step of calculating the calorific value, the step of measuring the inter-terminal voltage of the element to be measured over a predetermined measurement period, the amount of change in the inter-terminal voltage, and the temperature coefficient of the measurement current under energization conditions. A step of calculating the temperature change amount of the target element and a step of calculating the thermal resistance between the measurement target element and the heating target element from the temperature change amount of the measurement target element and the heat generation amount of the heating target element. It is said to have a configuration (first configuration).

The thermal resistance measurement method comprising the first configuration further includes a step of calculating the temperature coefficient from the terminal voltage-junction temperature characteristic of the measurement target element under the energization condition of the measurement current (second configuration). The configuration of) is recommended.

Further, in the thermal resistance measurement method having the first or second configuration, the measurement period is from immediately after the end of the heating period to at least until the change in the voltage between the terminals due to the temperature drop of the measurement target element converges. It is preferable to use a continuous configuration (third configuration).

Further, in the thermal resistance measuring method having any of the first to third configurations, the heating period is continued until at least the change in the voltage between the terminals due to the temperature rise of the measurement target element converges ( It is preferable to use the fourth configuration).

Further, the thermal resistance measuring device disclosed in the present specification measures the amount of temperature change of the measurement target element by measuring the voltage between the terminals while energizing the measurement target element with the measurement current. A thermal resistance measurement method comprising a first constant current circuit, a second constant current circuit that heats the element to be heated by energizing the element to be heated with a predetermined heating current, and the above-mentioned first to fourth configurations. The configuration (fifth configuration) includes a thermal resistance calculation unit for calculating the thermal resistance between the measurement target element and the heating target element.

The thermal resistance measuring device having the fifth configuration may be configured to further include a storage unit for storing the temperature coefficient (sixth configuration).

Further, in the thermal resistance measuring device having the fifth or sixth configuration, the first constant current circuit has a first constant current source for supplying the measured current to the measurement target element and terminals of the measurement target element. It is preferable to have a configuration (seventh configuration) including a first voltmeter for measuring the intercurrent voltage.

Further, in the thermal resistance measuring device having any of the fifth to seventh configurations, the second constant current circuit includes a second constant current source that supplies the heating current to the heating target element and the heating target element. It is preferable to have a configuration (eighth configuration) including a second voltmeter for measuring the voltage between terminals of the above and a heating current switch for conducting / blocking the energization path of the heating current.

Further, the device set disclosed in the present specification is a thermal resistance detection method including a device including the measurement target element and a plurality of elements to be the heating target element, and the above-mentioned first to fourth configurations. Alternatively, a data providing means for providing the customer with data indicating the thermal resistance between the measurement target element and the heating target element measured by using the thermal resistance measuring device having any of the fifth to eighth configurations. It is said that the configuration has (the ninth configuration).

In the device set having the ninth configuration, the data providing means is a data sheet in which a determinant including a thermal resistance between a plurality of elements is described, and a SPICE in which the thermal resistance between a plurality of elements is modeled. The configuration (10th configuration) may be a download site where the model or the thermal calculation model can be downloaded, or a simulator that provides a calculation service using the thermal resistance between the plurality of elements.

Further, the device set disclosed in the present specification provides the customer with data indicating the thermal resistance between the device including the measurement target element and the plurality of elements to be the heating target elements and the plurality of elements. The thermal resistance between the plurality of elements is such that a predetermined measurement current is applied to the measurement target element to heat the heating target element over a predetermined heating period, and the heating is performed. The calorific value of the target element is calculated, the terminal voltage of the measurement target element is measured over a predetermined measurement period, and the measurement target is measured from the change amount of the terminal voltage and the temperature coefficient of the measurement current under energization conditions. A configuration obtained by calculating the temperature change amount of the element and calculating the thermal resistance between the measurement target element and the heating target element from the temperature change amount of the measurement target element and the heat generation amount of the heating target element (11th). The composition of).

According to the thermal resistance measuring method disclosed in the present specification, it is possible to measure the thermal resistance between a plurality of elements.

The figure which shows one configuration example of a power module The figure which shows one configuration example of a thermal resistance measuring apparatus Flow chart showing an example of thermal resistance measurement method The figure which shows the voltage-junction temperature characteristic between terminals of a semiconductor element. Thermal resistance measurement time chart Diagram showing the first specific example of the device to be measured (circuit configuration) Diagram (layout) showing the first specific example of the device to be measured Diagram showing terminal connection pattern of thermal resistance measuring device The figure which shows the measurement result of thermal resistance The figure which shows one configuration example of the 1st constant current circuit The figure which shows one configuration example of the 2nd constant current circuit Diagram showing a second specific example of the device to be measured (circuit configuration) Diagram (layout) showing a second specific example of the device to be measured Diagram showing a third specific example of the device to be measured (circuit configuration) Diagram (layout) showing a third specific example of the device to be measured Diagram showing a fourth specific example of the device to be measured (circuit configuration) Diagram (layout) showing a fourth specific example of the device to be measured Diagram showing a fifth specific example of the device to be measured (circuit configuration) Diagram (layout) showing a fifth specific example of the device to be measured Diagram (layout) showing a sixth specific example of the device to be measured Diagram showing a first case of a device set provided to a customer Diagram showing a second case of a device set provided to a customer Diagram showing a third case of a device set provided to a customer

<Thermal resistance between multiple elements>
FIG. 1 is a diagram showing a configuration example of a power module in which it is desirable to measure the thermal resistance between a plurality of elements. The power module 100 of this configuration example is a full bridge module (4in1) having four semiconductor elements 101 to 104 (for example, SiC-N MOSFET [N-channel type metal oxide semiconductor field effect transistor]).

The thermal resistance Z [K / W] is an index indicating the heat dissipation performance of a semiconductor element mounted in a package such as a power module or a discrete device, and the temperature rise amount ΔT [of the semiconductor element per unit heat generation P [W]. It is defined by [K] (Z = ΔT / P).

As described in the section of background technology, all the conventional thermal resistance measurement methods target the thermal resistance of a single semiconductor element (see the black arrow in this figure), and are among a plurality of elements. Thermal resistance (see the white arrow in this figure) could not be measured.

However, in an environment in which a plurality of semiconductor elements 101 to 104 are mounted, for example, as in the power module 100 of this configuration example, the thermal resistance between the semiconductor elements 101 to 104 appears remarkably. In particular, in the power module 100 in which the semiconductor elements 101 to 104 are arranged at high density, the thermal resistance between the semiconductor elements 101 to 104 is large, so that the thermal problem becomes remarkable. Therefore, it is desirable to measure the thermal resistance between the semiconductor elements 101 to 104.

In the following, the power module 100 is used as a measurement target device, and a thermal resistance measuring device capable of measuring the thermal resistance between the semiconductor elements 101 to 104 built therein is proposed.

<Thermal resistance measuring device>
FIG. 2 is a diagram showing a configuration example of the thermal resistance measuring device 200. As shown in this figure, the thermal resistance measuring device 200 of this configuration example includes a first constant current circuit 210, a second constant current circuit 220, a thermal resistance calculation unit 230, and a storage unit 240. Further, the thermal resistance measuring device 200 includes at least terminals T1 to T4 as means for establishing an electrical connection with the power module 100.

The first constant current circuit 210 energizes the measurement target element # 1 (for example, the semiconductor element 101) with a predetermined measurement current Im (for example, 10 mA), and the terminal voltage (inter-terminal voltage) that appears between the drain and the source of the measurement target element # 1. For example, a circuit that measures the temperature change amount ΔT # 1 (= change amount of the junction temperature Tm) of the measurement target element # 1 by measuring the forward drop voltage of the body diode attached to the semiconductor element 101 as the measurement voltage Vfm. The constant current source 211 and the voltmeter 212 are included.

The constant current source 211 is connected between the terminal T1 and the terminal T2, and supplies a predetermined measurement current Im to the measurement target element # 1. It is desirable that the direction in which the measured current Im flows can be arbitrarily switched.

The voltmeter 212 is connected between the terminal T1 and the terminal T2, and measures the measured voltage Vfm that appears between the drain and the source of the measurement target element # 1.

The second constant current circuit 220 is a circuit that heats the heating target element # 2 by energizing the heating target element # 2 (for example, the semiconductor element 102) with a predetermined heating current Ih (for example, 10 to 100A). It includes a current source 221, a voltmeter 222, and a heating current switch 223.

The constant current source 221 is connected between the terminal T3 and the terminal T4, and supplies a predetermined heating current Ih to the heating target element # 2. It is desirable that the direction in which the heating current Ih flows can be arbitrarily switched.

The voltmeter 222 is connected between the terminal T3 and the terminal T4, and the voltage between the terminals appearing between the drain and the source of the element # 2 to be heated (for example, the forward voltage drop of the body diode attached to the semiconductor element 102). Is measured as a heating voltage Vfh.

The heating current switch 223 is connected between the terminal T4 (or the terminal T3) and the constant current source 221. When the heating current switch 223 is turned on, the heating current Ih flows through the heating target element # 2, so that the heating target element # 2 is heated. On the other hand, when the heating current switch 223 is turned off, the heating current Ih does not flow to the heating target element # 2, so that the heating of the heating target element # 2 is stopped.

The thermal resistance calculation unit 230 calculates the thermal resistance between the measurement target element # 1 and the heating target element # 2 by a new thermal resistance measurement method described later.

The storage unit 240 stores the temperature coefficient α (details will be described later) used for calculating the thermal resistance. When measuring the thermal resistance between the semiconductor elements 101 to 104 built in the power module 100, it is necessary to individually store the temperature coefficients of the semiconductor elements 101 to 104 in the storage unit 240.

For example, when the thermal resistance measuring device 200 of this configuration example is used to measure the thermal resistance of the semiconductor element 101 due to the heat generated by the semiconductor element 102, the terminals T1 and T2 are respectively connected to the semiconductor element 101 as shown in this figure. The drain and source (= d1 pin and s1 pin of the power module 100) may be connected, and the terminals T3 and T4 may be connected to the drain and source (= d2 pin and s2 pin of the power module 100) of the semiconductor element 102, respectively. .. By such terminal connection, it is possible to measure the thermal resistance between a plurality of elements by using the semiconductor element 101 as the detection target element # 1 and the semiconductor element 102 as the heating target element # 2.

Hereinafter, the thermal resistance measuring method using the thermal resistance measuring device 200 will be described in detail.

<Thermal resistance measurement method>
FIG. 3 is a flowchart showing an example of the thermal resistance measurement method. The gate control of each of the semiconductor elements 101 to 104 in this flow is arbitrary. For example, each of the semiconductor elements 101 to 104 may be in a full-off state, or may be in a half-on state or a full-on state. That is, the gates and sources of the semiconductor elements 101 to 104 may be short-circuited, or an arbitrary bias voltage (positive or negative) may be applied.

When this flow starts, first, in step S1, the measurement target element is determined from the terminal voltage-junction temperature characteristic (Vfm-Tm characteristic) of the measurement target element # 1 (for example, the semiconductor element 101) under the energization condition of the measurement current Im. The temperature coefficient α of # 1 is calculated.

FIG. 4 is a diagram showing the voltage-junction temperature characteristic (Vfm-Tm characteristic) between terminals of the measurement target element # 1 under the energization condition of the measurement current Im (for example, Im = 10 mA). The vertical axis of this figure shows the measurement voltage Vfm that appears between the drain and the source of the measurement target element # 1, and the horizontal axis of this figure shows the junction temperature Tm of the measurement target element # 1. Further, the black circles in the figure indicate the actually measured values of the measured voltage Vfm measured sequentially while changing the junction temperature Tm, and the broken lines in the figure are approximate expressions (Vfm = α) derived from a plurality of actually measured values. × Tm + β) is shown.

In the case of this figure, the measured voltage Vfm decreases as the junction temperature Tm increases. That is, it can be seen that the measured voltage Vfm has a negative temperature coefficient α (for example, α = −2.1 mV / K). The temperature coefficient α calculated in this way is stored in the storage unit 240.

The temperature coefficient α may be measured in advance by using a separate means prior to the implementation of the thermal resistance measurement operation (flow chart in FIG. 3) mainly composed of the thermal resistance measuring device 200. That is, if the temperature coefficient α is known, step S1 can be omitted.

Returning to FIG. 3, the explanation of the flowchart will be continued. After the temperature coefficient α is calculated in step S1, in step S2, the thermal resistance measurement standby period (= the period in which the start of energization of the heating current Ih is awaited) is set.

Next, in step S3, the measurement current Im is energized to the measurement target element # 1. For example, when the semiconductor element 101 is the measurement target element # 1, the measurement current Im flows from the terminal T2 to the terminal T2 via the semiconductor element 101 (particularly the body diode). The measured current Im continues to be energized to the measurement target element # 1 while being constantly maintained at a constant set value (= 10 mA, which is the same as the set value in step S1) during the thermal resistance measurement operation.

Next, in step S4, the heating current switch 223 is turned on, and the energization path of the heating current Ih is conducted. For example, when the semiconductor element 102 is the element # 2 to be heated, a heating current Ih (for example, 10 to 100 A) flows from the terminal T4 to the terminal T3 via the semiconductor element 102 (particularly a body diode). As a result, heating of the heating target element # 2 is started.

Next, in step S5, the calorific value P # 2 (= Ih × Vfh) of the heating target element # 2 is calculated by measuring and integrating the heating current Ih and the heating voltage Vfh, respectively.

Next, in step S6, the heating current switch 223 is turned off, and the energization path of the heating current Ih is cut off. As a result, the heating of the element # 2 to be heated is stopped.

As described above, in steps S4 to S6, the heating target element # 2 is heated over a predetermined heating period.

The heating period may be set to an appropriate length according to the heat capacity of each of the measurement target element # 1 and the heating target element # 2. More specifically, the above heating period may be continued from the start of heating of the heating target element # 2 until at least the change (decrease) of the measurement voltage Vfm accompanying the temperature rise of the measurement target element # 1 converges.

Further, the calculation of the calorific value P # 2 in step S5 is performed after the change (decrease) in the heating voltage Vfh due to the temperature rise of the heating target element # 2 has converged, for example, immediately before the end of the heating period (= immediately before the end of step S6). ) Is desirable.

Next, in step S7, the measurement voltage Vfm that appears between the drain and source of the measurement target element # 1 is measured over a predetermined measurement period. For example, the above measurement period may be continued from immediately after the end of the heating period until at least the change (rise) of the measurement voltage Vfm due to the temperature decrease of the measurement target element # 1 converges.

In step S7, for convenience of explanation, it is described as if the measurement of the measurement voltage Vfm is started immediately after the end of the heating period, but in reality, the measurement voltage is measured after the start of energization of the measurement current Im in step S3. It is desirable to continue measuring Vfm.

Next, in step S8, the temperature change amount ΔT # 1 (= ΔVfm / α) of the measurement target element # 1 is obtained from the change amount ΔVfm of the measured voltage Vfm obtained in step S7 and the temperature coefficient α obtained in step S1. Calculated.

Finally, in step S9, from the temperature change amount ΔT # 1 of the measurement target element # 1 obtained in step S8 and the calorific value P # 2 of the heating target element # 2 obtained in step S5, the measurement target element # 1 and The thermal resistance Z12 (= ΔT # 1 / P # 2) between the elements to be heated # 2 is calculated, and the above series of flows is completed.

FIG. 5 is a measurement time chart of thermal resistance, in which the measurement current Im, the measurement voltage Vfm, the heating current Ih, and the heating voltage Vfh are depicted in order from the top.

Times t0 to t1 correspond to the above-mentioned measurement standby period (= steps S2 to S3 in FIG. 3). That is, the measurement current Im is energized, but the heating current Ih is not energized. As described above, the measurement current Im continues to be energized to the measurement target element # 1 while being constantly maintained at a constant set value during the thermal resistance measurement operation.

Times t1 to t2 correspond to the above-mentioned heating period (= steps S4 to S6 in FIG. 3). That is, at time t1, the heating current switch 223 is turned on and the energization path of the heating current Ih is conducted, so that the heating target element # 2 is started to be heated. On the other hand, at time t2, the heating current switch 223 is turned off and the energization path of the heating current Ih is cut off, so that the heating of the heating target element # 2 is stopped.

When the heating of the heating target element # 2 is started at the time t1, the junction temperature Tm of the measurement target element # 1 also starts to rise due to the heat transfer from the heating target element # 2 to the measurement target element # 1. Therefore, the measured voltage Vfm having a negative temperature coefficient α decreases as the junction temperature Tm rises after time t1. The heating period may be continued at least until the decrease in the measured voltage Vfm converges.

Further, in this figure, the heating voltage Vfh during the heating period is depicted as if it is a constant value, but in reality, after the time t1, the heating voltage Vfh also decreases as the temperature of the heating target element # 2 rises. .. Therefore, it is desirable to calculate the calorific value P # 2 (= Ih × Vfh) of the element # 2 to be heated immediately before the end of the heating period (= immediately before the time t3).

The times t2 to t3 correspond to the above-mentioned measurement period (= step S7 in FIG. 3). When the heating of the element # 2 to be heated is stopped at the time t2, the junction temperature Tm of the element # 1 to be measured starts to decrease, so that the measurement voltage Vfm increases. The above measurement period may be continued, for example, immediately after the end of the heating period until at least the increase in the measurement voltage Vfm converges.

After that, the temperature change amount ΔT # 1 (= ΔVfm / α) of the measurement target element # 1 is calculated from the change amount ΔVfm of the measurement voltage Vfm obtained in the above measurement period and the temperature coefficient α measured in advance. Further, the thermal resistance Z12 (= ΔT # 1 / P # 2) between the measurement target element # 1 and the heating target element # 2 is calculated from the calculation result and the calorific value P # 2 of the heating target element # 2. Will be done. This point is as described in steps S8 and S9 of FIG.

In FIGS. 3 and 4, an example in which the amount of increase in the measured voltage Vfm is measured after the end of the heating period is given as the amount of change ΔVfm in the measured voltage Vfm. For example, the amount of decrease in the measured voltage Vfm during the heating period. Is not impossible to measure.

<Measurement target device (first specific example)>
6 and 7 are diagrams (circuit configuration and layout) showing a first specific example of the device to be measured, respectively.

The measurement target device 110 of this specific example is a full bridge module (4in1) in which semiconductor elements 111 and 112 (for example, SiC-NMOSFET) and semiconductor elements 113 and 114 (for example, Si-FRD [fast recovery diode]) are built in a package 115. Is. Further, the package 115 contains substrates 116a to 116e (for example, Cu substrates) having high electrical conductivity or thermal conductivity.

Both the drain (back surface) of the semiconductor element 111 and the cathode (back surface) of the semiconductor element 113 are surface-mounted on the substrate 116a. The substrate 116a is bonded to the P1 pin via the wire W1. The source (surface) of the semiconductor element 111 is bonded to the substrate 116d via the wire W4, and is also bonded to the S1 pin via the wire W10. The gate (surface) of the semiconductor element 111 is bonded to the G1 pin via the wire W9. The anode (surface) of the semiconductor element 113 is bonded to the substrate 116c via the wire W3. The substrate 116c is conducted to the substrate 116e via the bridge 117.

The drain (back surface) of the semiconductor element 112 is surface-mounted on the substrate 116d. The substrate 116d is bonded to the + pin via the wire W7. The source (surface) of the semiconductor element 112 is bonded to the substrate 116b via the wire W5, and is also bonded to the S2 pin via the wire W12. The gate (surface) of the semiconductor element 112 is bonded to the G2 pin via the wire W11.

The cathode (back surface) of the semiconductor 114 is surface-mounted on the substrate 116e. The substrate 116e is bonded to the − pin via the wire W8. The anode (surface) of the semiconductor element 114 is bonded to the substrate 116b via the wire W6. The substrate 116b is bonded to the N1 pin via the wire W2.

That is, both the drain of the semiconductor element 111 and the cathode of the semiconductor element 113 are connected to the P1 pin. The gate of the semiconductor element 111 is connected to the G1 pin. Both the source of the semiconductor element 111 and the drain of the semiconductor element 112 are connected to the + pin. The source of the semiconductor element 112 is also connected to the S1 pin. Both the source of the semiconductor element 112 and the anode of the semiconductor element 114 are connected to the N1 pin. The source of the semiconductor element 112 is also connected to the S2 pin. The gate of the semiconductor element 112 is connected to the G2 pin. Both the anode of the semiconductor element 113 and the cathode of the semiconductor element 114 are connected to the − pin.

If the signal source terminal for driving the gate has S1 pin and S2 pin, the gate drive of each of the semiconductor elements 111 and 112 can be performed without being affected by the inductance component associated with the current path. ..

Further, the wires W1 to W8 serving as the current path may have a larger diameter than the wires W9 to W12 serving as the signal path.

As described above, different types of elements (for example, transistors and diodes) may be mixed as the semiconductor elements 111 to 114 built in the measurement target device 110.

FIG. 8 is a diagram showing a terminal connection pattern between the measurement target device 110 (FIG. 6) and the thermal resistance measuring device 200 (FIG. 2). In the leftmost column of this figure, "Zmn" uses a semiconductor element 11m (however, m = 1 to 4) as a measurement target element, and a semiconductor element 11n (however, n = 1 to 4 and n ≠ m). The thermal resistance between the semiconductor elements 11m and 11n measured as the element to be heated (= the thermal resistance of the semiconductor element 11m due to the heat generated by the semiconductor element 11n) is shown.

For example, when measuring the thermal resistance Z12, the terminals T1 and T2 may be connected to the P1 pin and the S1 pin, respectively, and the terminals T3 and T4 may be connected to the + pin and the S2 pin, respectively. Further, when measuring the thermal resistance Z13, the terminals T1 and T2 may be connected in the same manner as described above, and the terminals T3 and T4 may be connected to the P1 pin and the − pin, respectively. Further, when measuring the thermal resistance Z14, the terminals T1 and T2 may be connected in the same manner as described above, and the terminals T3 and T4 may be connected to the − pin and the S2 pin, respectively.

When measuring the thermal resistance Z21, the terminals T1 and T2 may be connected to the + pin and the S2 pin, respectively, and the terminals T3 and T4 may be connected to the P1 pin and the S1 pin, respectively. Further, when measuring the thermal resistance Z23, the terminals T1 and T2 may be connected in the same manner as described above, and the terminals T3 and T4 may be connected to the P1 pin and the − pin, respectively. Further, when measuring the thermal resistance Z24, the terminals T1 and T2 may be connected in the same manner as described above, and the terminals T3 and T4 may be connected to the − pin and the S2 pin, respectively.

When measuring the thermal resistance Z31, the terminals T1 and T2 may be connected to the P1 pin and the − pin, respectively, and the terminals T3 and T4 may be connected to the P1 pin and the S1 pin, respectively. Further, when measuring the thermal resistance Z32, the terminals T1 and T2 may be connected in the same manner as described above, and the terminals T3 and T4 may be connected to the + pin and the S2 pin, respectively. Further, when measuring the thermal resistance Z34, the terminals T1 and T2 may be connected in the same manner as described above, and the terminals T3 and T4 may be connected to the − pin and the S2 pin, respectively.

When measuring the thermal resistance Z41, the terminals T1 and T2 may be connected to the − pin and the S2 pin, respectively, and the terminals T3 and T4 may be connected to the P1 pin and the S1 pin, respectively. Further, when measuring the thermal resistance Z42, the terminals T1 and T2 may be connected in the same manner as described above, and the terminals T3 and T4 may be connected to the + pin and the S2 pin, respectively. Further, when measuring the thermal resistance Z43, the terminals T1 and T2 may be connected in the same manner as described above, and the terminals T3 and T4 may be connected to the P1 pin and the − pin, respectively.

Since the thermal resistances Z11, Z22, Z33 and Z44 of each of the semiconductor elements 111 to 114 may be measured by the conventional thermal resistance measuring method, detailed description thereof will be omitted.

FIG. 9 is a diagram showing the measurement results of the thermal resistance Zmn (particularly, the thermal resistances Z11 to Z14 with the semiconductor element 111 as the measurement target element). The vertical axis shows the thermal resistance Zmn, and the horizontal axis shows the time logarithmically.

From this figure, it is natural that the thermal resistance Z11 (solid line) of the semiconductor element 111 itself is the maximum, and for the thermal resistances Z12 to Z14 between the plurality of elements, the thermal resistance Z13 (large broken line) between the semiconductor elements 111 and 113 is observed. ) Is the largest, followed by the thermal resistance Z12 (small broken line) between the semiconductor elements 111 and 112, and the thermal resistance Z14 (single point chain line) between the semiconductor elements 111 and 114 is the smallest. The reason is that the semiconductor element 113 is mounted on the substrate 116a common to the semiconductor element 111, and the distance between them is short.

<1st constant current circuit>
FIG. 10 is a diagram showing a configuration example of the first constant current circuit 210. In the first constant current circuit 210 of this configuration example, the constant current source 211 that energizes the measurement target element # 1 with the measurement current Im includes a voltage source E1, a constant current regulator IREG, and a sense resistor Rs1.

The positive end of the voltage source E1 is connected to the terminal T2. A constant current regulator IREG and a sense resistor Rs1 are connected between the terminal T1 and the negative end of the voltage source E1.

The sense resistor Rs1 converts the measured current Im into a sense voltage Vs (= Im × Rs1).

The constant current regulator IREG controls the constant current of the measured current Im so that the sense voltage Vs1 matches the predetermined reference voltage Vref. As the constant current regulator IREG, an LED [light emitting diode] driver IC or the like can be preferably used.

<Second constant current circuit>
FIG. 11 is a diagram showing a configuration example of the second constant current circuit 220. The second constant current circuit 220 of this configuration example includes an ammeter 224 and an insulated gate driver 225 in addition to the above-mentioned components (constant current source 221, voltmeter 222, and heating current switch 223).

The ammeter 224 includes a sense resistor Rs2 provided between the terminal T4 and the heating current switch 223, and detects the heating current Ih energized in the element # 2 to be heated as a sense voltage Vs2 (= Ih × Rs2). To do.

The insulated gate driver 225 electrically insulates between the primary circuit system (VCC1-GND1) and the secondary circuit system (VCC2-GND2), and sets the gate signal G1 of the primary circuit system to the gate signal of the secondary circuit system. It is transmitted as G2 and output to the gate of the transistor used as the heating current switch 223.

However, the heating current switch 223 is not limited to the transistor, and a mechanical relay or the like may be used.

<Measurement target device (second specific example)>
12 and 13 are diagrams showing diagrams (circuit configuration and layout) showing a second specific example of the device to be measured, respectively.

The measurement target device 120 of this specific example is a half-bridge module (2in1) in which semiconductor elements 121 and 122 (for example, SiC-NMOSFET) are built in a package 123. Further, the package 123 contains substrates 124a to 124c (for example, Cu substrates) having high electrical conductivity or thermal conductivity.

The drain (back surface) of the semiconductor element 121 is surface-mounted on the substrate 124a. The substrate 124a is conductive with the P pin. The source (surface) of the semiconductor element 121 is bonded to the substrate 124b via the wire W21, and is also bonded to the S1 pin via the wire W23. The gate (surface) of the semiconductor element 121 is bonded to the G1 pin via the wire W24.

The drain (back surface) of the semiconductor element 122 is surface-mounted on the substrate 124b. The substrate 124b is conductive with the O pin. The source (surface) of the semiconductor element 122 is bonded to the substrate 124c via the wire W22, and is also bonded to the S2 pin via the wire W25. The gate (surface) of the semiconductor element 122 is bonded to the G2 pin via the wire W26. The substrate 124c is conductive with the N pin.

That is, the drain of the semiconductor element 121 is connected to the P pin. The gate of the semiconductor element 121 is connected to the G1 pin. Both the source of the semiconductor element 121 and the drain of the semiconductor element 122 are connected to the O pin. The source of the semiconductor element 122 is also connected to the S1 pin. The source of the semiconductor element 122 is connected to the N pin and the S2 pin. The gate of the semiconductor element 122 is connected to the G2 pin.

If the signal source terminal for driving the gate has S1 pin and S2 pin, the gate drive of each of the semiconductor elements 111 and 112 can be performed without being affected by the inductance component associated with the current path. ..

Further, the wires W21 and W22 serving as the current path may have a larger diameter than the wires W23 to W26 serving as the signal path.

As described above, the measurement target device 120 in which the two semiconductor elements 121 and 122 are mounted on the substrates 124a and 124b having different potentials is one of the most basic examples as a target for measuring the thermal resistance between a plurality of elements. is there.

<Measurement target device (third specific example)>
14 and 15 are diagrams showing diagrams (circuit configuration and layout) showing a third specific example of the device to be measured, respectively.

The measurement target device 130 of this specific example is a three-phase bridge module (6in1) in which semiconductor elements 131 to 136 (for example, SiC-NMOSFET) are built in a package 137. Further, the package 137 contains substrates 138a to 138d (for example, Cu substrates) having high electrical conductivity or thermal conductivity.

The drains (back surfaces) of the semiconductor elements 131 to 133 are all surface-mounted on the substrate 138a. The substrate 138a is conducted to the P pin. The source (surface) of the semiconductor element 131 is bonded to the substrate 138b (U pin) via the wire W31, and is also bonded to the S1 pin via the wire W38. The gate (surface) of the semiconductor element 131 is bonded to the G1 pin via the wire W37. The source (surface) of the semiconductor element 132 is bonded to the substrate 138c (V pin) via the wire W32, and is also bonded to the S2 pin via the wire W3a. The gate (surface) of the semiconductor element 132 is bonded to the G2 pin via the wire W39. The source (surface) of the semiconductor element 133 is bonded to the substrate 138d (W pin) via the wire W34, and is also bonded to the S3 pin via the wire W3c. The gate (surface) of the semiconductor element 133 is bonded to the G3 pin via the wire W3b.

The drain (back surface) of the semiconductor element 134 is surface-mounted on the substrate 138b. The substrate 138b is conducted to the U pin. The source (surface) of the semiconductor element 134 is bonded to the N pin (NU pin) via the wire W34, and is also bonded to the S4 pin via the wire W3e. The gate (surface) of the semiconductor element 134 is bonded to the G4 pin via the wire W3d.

The drain (back surface) of the semiconductor element 135 is surface-mounted on the substrate 138c. The substrate 138c is conducted to the V pin. The source (surface) of the semiconductor element 135 is bonded to the N pin (NV pin) via the wire W35, and is also bonded to the S5 pin via the wire W3g. The gate (surface) of the semiconductor element 135 is bonded to the G5 pin via the wire W3f.

The drain (back surface) of the semiconductor element 136 is surface-mounted on the substrate 138d. The substrate 138d is conducted to the W pin. The source (surface) of the semiconductor element 136 is bonded to the N pin (NW pin) via the wire W36, and is also bonded to the S6 pin via the wire W3i. The gate (surface) of the semiconductor element 136 is bonded to the G6 pin via the wire W3h.

That is, the drains of the semiconductor elements 131 to 133 are all connected to the P pin. The sources of each of the semiconductor elements 134 to 136 are connected to the N pin. Both the source of the semiconductor element 131 and the drain of the semiconductor element 134 are connected to the U pin. Both the source of the semiconductor element 132 and the drain of the semiconductor element 135 are connected to the V pin. Both the source of the semiconductor element 133 and the drain of the semiconductor element 136 are connected to the W pin. The gates of the semiconductor elements 131 to 136 are connected to pins G1 to G6. Further, the sources of the semiconductor elements 131 to 136 are connected to pins S1 to S6.

If the signal source terminal for driving the gate has S1 pins to S6 pins, the gate drive of each of the semiconductor elements 131 to 136 can be performed without being affected by the inductance component associated with the current path. ..

Further, the wires W31 to W36 serving as the current path may have a larger diameter than the wires W37 to W3i serving as the signal path.

As described above, even if a plurality of the semiconductor elements 131 to 136 built in the measurement target device 130 are arranged on a common substrate, if the current loops for each element can be separated from each other, the above-mentioned thermal resistance It can be a target for measuring the thermal resistance between a plurality of elements using a detection method.

<Measurement target device (4th specific example)>
16 and 17 are diagrams (circuit configuration and layout) showing a fourth specific example of the device to be measured, respectively.

The measurement target device 140 of this specific example is a discrete device in which semiconductor elements 141 and 142 (for example, SiC-SBD [Schottky barrier diode]) are built in a package 143. Further, the package 140 contains a substrate 144 (for example, a Cu substrate) having high electrical conductivity or thermal conductivity.

The cathodes (back surfaces) of the semiconductor elements 141 and 142 are surface-mounted on the substrate 144. The substrate 144 is led out to the outside of the package 143 as a C pin. The anode (surface) of the semiconductor element 141 is bonded to the A1 pin via the wire W41. The anode (surface) of the semiconductor element 142 is bonded to the A2 pin via the wire W42.

That is, the cathodes of the semiconductor elements 141 and 142 are connected to the C pin. The anode of the semiconductor element 141 is connected to the A1 pin. The anode of the semiconductor element 142 is connected to the A2 pin.

As described above, even in a discrete device, if a plurality of semiconductor elements 141 and 142 are included in the same package 143, the target for measuring the thermal resistance between the plurality of elements using the above-mentioned thermal resistance detection method. Can be.

<Measurement target device (5th specific example)>
18 and 19 are diagrams showing diagrams (circuit configuration and layout) showing a fifth specific example of the device to be measured, respectively.

In the measurement target device 150 of this specific example, semiconductor elements 151 and 152 (for example, SiC-NMOSFET), which are discrete devices, are inserted and mounted on the circuit board 153. For example, a half bridge can be formed by connecting the S1 pin of the semiconductor element 151 and the D1 pin of the semiconductor element 152. Further, the semiconductor elements 151 and 152 are screwed to the heat sink 154 having high thermal conductivity. Such mounting conditions are often found in actual circuits (for example, AC / DC power supplies).

As described above, when the semiconductor elements 151 and 152 are mounted on the same heat sink 154, thermal interference occurs even between discrete devices. Therefore, it can be a target for measuring the thermal resistance between a plurality of elements by using the above-mentioned thermal resistance detection method.

In this figure, an example in which two discrete devices are mounted on the same heat sink is shown. However, if the above-mentioned thermal resistance detection method is used, even if there are three or more discrete devices, the heat between a plurality of elements can be obtained. It goes without saying that resistance can be measured.

<Measurement target device (6th specific example)>
FIG. 20 is a diagram (layout) showing a sixth specific example of the device to be measured. In the measurement target device 160 of this specific example, semiconductor elements 161 and 162 (for example, SiC-NMOSFET), which are discrete devices, are surface-mounted on the circuit board 163.

The circuit configuration of the device 160 to be measured is the same as that shown in FIG. 18, and it is sufficient to read the reference numerals 150 to 153 in the figure with the reference numerals 160 to 163, respectively, and thus the duplicate description will be omitted.

Here, when the mounting positions of the semiconductor elements 161 and 162 on the circuit board 163 are close to each other, thermal interference occurs even between the discrete devices via the circuit board 163. Therefore, it can be a target for measuring the thermal resistance between a plurality of elements by using the above-mentioned thermal resistance detection method.

In this figure, an example in which two discrete devices are mounted on the same circuit board is given, but if the above-mentioned thermal resistance detection method is used, even if there are three or more discrete devices, between a plurality of elements. Needless to say, it is possible to measure the thermal resistance of.

<Measurement target device (others)>
In the above-mentioned first to sixth specific examples, an example in which a plurality of semiconductor elements (measurement target element and heating target element) form a single circuit has been given. For example, the measurement target element and the heating target element may be used. Even if they are components of different circuits, they can be objects for measuring the thermal resistance between a plurality of elements by using the above-mentioned thermal resistance detection method as long as they can cause mutual thermal interference.

Further, the measurement target element and the heating target element are not necessarily limited to the semiconductor element, and for example, the heating target element may be a resistance element, a nichrome wire, or the like.

<Device set (first case)>
FIG. 21 is a diagram showing a first case of a device set provided to a customer (user). The device set 300 of this example includes a device 310 including a plurality of elements (for example, semiconductor elements # 1 to # 4) and a data sheet 320.

The data sheet 320 is an example of a data providing means for providing a customer with data indicating a thermal resistance Zmn between a plurality of elements measured by using the above-mentioned novel thermal resistance measuring method.

For the semiconductor elements # 1 to # 4, the amount of temperature change is ΔT1 to ΔT4, and the amount of heat generated is P1 to P4. Further, the thermal resistance due to self-heating of each of the semiconductor elements # 1 to # 4 is set to Z11, Z22, Z33 and Z44. Further, the semiconductor elements # m and # are measured with the semiconductor element #m (where m = 1 to 4) as the measurement target element and the semiconductor element # n (where n = 1 to 4 and n ≠ m) as the heating target element. n Let the thermal resistance between each other be Zmn.

At this time, the following determinant (1) is established between the various parameters described above.

In the conventional data sheet, only the thermal resistances Z11, Z22, Z33 and Z44 (only the underlined part of the determinant) due to the self-heating of each of the semiconductor elements # 1 to # 4 are described.

On the other hand, if a novel thermal resistance measuring method is used, the thermal resistance Zmn (other than the underlined portion of the determinant) between a plurality of elements can be measured. Therefore, the determinant (1) including the thermal resistance Zmn can be described in the data sheet 320 and provided to the customer together with the device 310.

As the thermal resistance Z11, Z22, Z33 and Z44 due to the self-heating of each of the semiconductor elements # 1 to # 4, and the thermal resistance Zmn between the plurality of elements, the measured values of the saturated thermal resistance may be described respectively. Alternatively, a measurement graph of transient thermal resistance may be described. Alternatively, both saturated thermal resistance and transient thermal resistance may be described.

<Device set (second case)>
FIG. 22 is a diagram showing a second case of a device set provided to a customer (user). The device set 300 of this example has the above-mentioned device 310 and a download site 330.

The download site 330 is an example of a data providing means for providing a customer with data indicating the thermal resistance Zmn between a plurality of elements measured by using the above-mentioned novel thermal resistance measuring method.

More specifically, in addition to the data sheet of the device 310, the SPICE model and the thermal calculation model (= model for performing the calculation of the thermal circuit on the electric circuit) are uploaded to the download site 330. Therefore, the customer who has accessed the download site 330 can arbitrarily download the above data sheet, the SPICE model, and the thermal calculation model.

In the conventional SPICE model and the thermal calculation model, only the thermal resistances Z11, Z22, Z33 and Z44 (only the underlined portion of the determinant) due to the self-heating of the semiconductor elements # 1 to # 4 are considered.

On the other hand, if a novel thermal resistance measuring method is used, the thermal resistance Zmn (other than the underlined portion of the determinant) between a plurality of elements can be measured. Therefore, not only the thermal resistances Z11, Z22, Z33 and Z44, but also the SPICE model and the thermal resistance model modeled in consideration of the thermal resistance Zmn between a plurality of elements are uploaded to the download site 330 and provided to the customer together with the device 310. It becomes possible to do. Customers can use these SPIC models and thermal resistance models to perform more accurate simulations.

<Device set (3rd case)>
FIG. 23 is a diagram showing a third example of a device set provided to a customer (user). The device set 300 of this example has the above-mentioned device 310 and a web simulator 340 (= web-mounted simulator).

The web simulator 340 is an example of a data providing means for providing a customer with data indicating a thermal resistance Zmn between a plurality of elements measured by using the above-mentioned novel thermal resistance measuring method.

More specifically, the web simulator 340 provides an arithmetic service using the above-mentioned determinant (1). For example, when the customer inputs the temperature change amounts ΔT1 to ΔT4 of each of the semiconductor elements # 1 to # 4 in the specification circuit, the calorific value P1 to P4 satisfying the temperature change amounts P1 to P4 are output. On the contrary, when the customer inputs the calorific value P1 to P4 of each of the semiconductor elements # 1 to # 4 in the specification circuit, the temperature change amounts ΔT1 to ΔT4 corresponding to the input are output.

With the above service provision, it is possible to confirm in advance whether or not the device 310 is thermally okay in the application in which the customer intends to apply the device 310.

The simulator that provides the above calculation service is not necessarily limited to the web-implemented type, and is, for example, software (so-called simulation software) that is compiled into an executable file (exe file) and provided to the customer. It doesn't matter.

<Other variants>
In addition to the above-described embodiment, the various technical features disclosed in the present specification can be modified in various ways without departing from the spirit of the technical creation. That is, it should be considered that the above-described embodiment is exemplary in all respects and is not restrictive, and the technical scope of the present invention is not limited to the above-described embodiment, and claims for patent. It should be understood that the meaning equal to the scope and all changes belonging to the scope are included.

The invention disclosed in the present specification can be suitably used, for example, as a means for measuring the thermal resistance between a plurality of semiconductor elements arranged at high density in a power module.

100 Power module 101-104 Semiconductor element 110 Measurement target device 111-114 Semiconductor element 115 Package 116a to 116e Substrate 117 Bridge 120 Measurement target device 121, 122 Semiconductor element 123 Package 124a to 124c Substrate 130 Measurement target device 131-136 Semiconductor element 137 Package 138a to 138d Substrate 140 Measurement target device 141, 142 Semiconductor element 143 Package 144 Substrate 150 Measurement target device 151, 152 Semiconductor element 153 Circuit board 154 Heat sink 160 Measurement target device 161, 162 Semiconductor element 163 Circuit board 200 Thermal resistance measuring device 210 1st constant current circuit 211 constant current source 212 voltmeter 220 2nd constant current circuit 221 constant current source 222 voltmeter 223 heating current switch 224 current meter 225 insulated gate driver 230 thermal resistance calculation unit 240 storage unit 300 device set 310 devices 320 Data Sheet 330 Download Site 340 Web Simulator E1 Voltage Source IREG Constant Current Regulator Rs1, Rs2 Sense Resistance T1-T4 Terminals W1-W12, W21-W26, W31-W3i, W41-W42 Wire # 1 Measurement Target Element # 2 Heating Target element

Claims (11)

The step of energizing the element to be measured with a predetermined measurement current,
A step of heating the element to be heated over a predetermined heating period,
The step of calculating the calorific value of the element to be heated and
A step of measuring the voltage between terminals of the element to be measured over a predetermined measurement period, and
A step of calculating the temperature change amount of the measurement target element from the change amount of the voltage between the terminals and the temperature coefficient under the energization condition of the measurement current, and
A step of calculating the thermal resistance between the measurement target element and the heating target element from the temperature change amount of the measurement target element and the heat generation amount of the heating target element, and
A method for measuring thermal resistance, which comprises. The thermal resistance measurement method according to claim 1, further comprising a step of calculating the temperature coefficient from the terminal voltage-junction temperature characteristic of the measurement target element under the energization condition of the measurement current. The first or second aspect of the present invention, wherein the measurement period is continued immediately after the end of the heating period until at least the change in the voltage between the terminals due to the temperature drop of the measurement target element converges. Thermal resistance measurement method. The thermal resistance according to any one of claims 1 to 3, wherein the heating period is continued at least until the change in the voltage between the terminals due to the temperature rise of the measurement target element converges. Measurement method. A first constant current circuit that measures the amount of temperature change of the measurement target element by measuring the voltage between the terminals while energizing the measurement target element.
A second constant current circuit that heats the element to be heated by energizing the element to be heated by a predetermined heating current, and a second constant current circuit.
A thermal resistance calculation unit that calculates the thermal resistance between the measurement target element and the heating target element by the thermal resistance measurement method according to any one of claims 1 to 4.
A thermal resistance measuring device characterized by having. The thermal resistance measuring device according to claim 5, further comprising a storage unit that stores the temperature coefficient. The first constant current circuit is
A first constant current source that supplies the measured current to the measurement target element,
A first voltmeter that measures the voltage between the terminals of the element to be measured, and
The thermal resistance measuring device according to claim 5 or 6, wherein the thermal resistance measuring device includes the above. The second constant current circuit is
A second constant current source that supplies the heating current to the element to be heated,
A second voltmeter that measures the voltage between the terminals of the element to be heated,
A heating current switch that conducts / cuts off the energization path of the heating current,
The thermal resistance measuring apparatus according to any one of claims 5 to 7, further comprising. A device including the measurement target element and a plurality of elements to be the heating target element,
The measurement target measured using the thermal resistance detection method according to any one of claims 1 to 4 or the thermal resistance measuring device according to any one of claims 5 to 8. A data providing means for providing a customer with data indicating the thermal resistance between the element and the element to be heated, and
A device set characterized by having. The data providing means is a download site where a data sheet in which a matrix formula including a thermal resistance between a plurality of elements is described, a SPICE model in which the thermal resistance between a plurality of elements is modeled, or a thermal calculation model can be downloaded. Alternatively, the device set according to claim 9, wherein the simulator is a simulator that provides an arithmetic service using the thermal resistance between the plurality of elements. A device including the measurement target element and a plurality of elements to be the heating target element,
A data providing means for providing a customer with data indicating thermal resistance between the plurality of elements,
Have,
The thermal resistance between the plurality of elements is determined by energizing the measurement target element with a predetermined measurement current, heating the heating target element over a predetermined heating period, calculating the calorific value of the heating target element, and determining the heat resistance. The inter-terminal voltage of the measurement target element is measured over the measurement period of the above, and the temperature change amount of the measurement target element is calculated from the change amount of the terminal-to-terminal voltage and the temperature coefficient under the energization condition of the measurement current. A device set characterized in that the thermal resistance between the measurement target element and the heating target element is calculated from the temperature change amount of the measurement target element and the calorific value of the heating target element.

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