JP2023171330A - Thermal resistance measuring device - Google Patents

Abstract

To provide a thermal resistance measuring device with which it is possible to measure the thermal resistance of a measurement object composed of a planar body with higher accuracy.SOLUTION: A thermal resistance measuring device comprises: a heating body that heats one plane of a measurement object S; a high temperature side thin film thermocouple 16A that is interposed between the measurement object S and the heating body and comes into contact with the measurement object; a low temperature side thin film thermocouple 16B that comes into contact with the measurement object S at a position different from a position where the heating body heats the measurement object S; and a thermal resistance calculation processor that calculates a high temperature side surface temperature on the basis of the output signal of the high temperature side thin film thermocouple 16A, calculates a low temperature side surface temperature on the basis of the output signal of the low temperature side thin film thermocouple 16B, and calculates the thermal resistance of the measurement object S on the basis of the temperature difference between the high temperature side surface temperature and the low temperature side surface temperature.SELECTED DRAWING: Figure 3

Description

The present invention relates to a thermal resistance measuring device, and particularly to a thermal resistance measuring device using a thermocouple.

In recent years, in order to suppress global warming, the ways in which electric energy is used have been diversifying, as exemplified by the spread of electric vehicles and renewable energy. Along with this, the demand for power semiconductor devices used when utilizing various electric power energies is increasing.
Here, since power semiconductor elements generate heat when driven, they are used together with a heat radiation member, a cooling member, or a heat transfer member as a measure against heat generation.

A thermally conductive sheet that functions as a heat transfer member is placed between a power semiconductor element and a heat radiation member or a cooling member to effectively radiate or cool the heat generated from the power semiconductor element. It is used to As the thermally conductive sheet, a silicone sheet or a fluororesin sheet having high thermal conductivity and electrical insulation properties is known.

On the other hand, in parallel with the spread of thermally conductive sheets, the development of thermal resistance measuring devices used to measure the thermal properties of thermally conductive sheets, specifically, thermal resistance, has been progressing. Patent Document 1 discloses a thermal resistance measuring device that can efficiently measure the thermal resistance of a plurality of thermally conductive sheets.

Japanese Patent Application Publication No. 2008-134111

By using the thermal resistance measuring device disclosed in Patent Document 1, it is possible to measure the thermal resistance of a thermally conductive sheet, and based on the measurement results, it is possible to effectively radiate heat generated by power semiconductor elements. or cooling.
However, it has been desired to further improve the measurement accuracy of thermal resistance measuring devices. This will be explained in detail below.

FIG. 8 is a diagram for explaining the principle of measuring thermal resistance using a conventional thermal resistance measuring device. As shown in FIG. 8, the thermal resistance measuring device 101 holds a thermally conductive sheet S, which is an object to be measured, between a high temperature rod 104 heated by a heater 103 and a low temperature rod 106 cooled by a cooler 107. do.
In the high temperature rod 104 heated by the heater 103, a temperature gradient occurs in which the temperature decreases from the bottom to the top in FIG. On the other hand, in the low-temperature rod 106 cooled by the cooler 107, a temperature gradient occurs in which the temperature increases from the top to the bottom.

Thermocouples 105 are attached to the high-temperature rod 104 and the low-temperature rod 106 to measure their respective temperature gradients. Specifically, three thermocouples 105 are attached to the high temperature rod 104: a first high temperature thermocouple 105A, a second high temperature thermocouple 105B, and a third high temperature thermocouple 105C. Similarly, three thermocouples 105 are attached to the low temperature rod 106: a first low temperature thermocouple 105F, a second low temperature thermocouple 105E, and a third low temperature thermocouple 105D.

A calculation unit (not shown) electrically connected to the plurality of thermocouples 105 calculates the temperature T1 at the contact portion between the high temperature rod 104 and the heat conductive sheet S and the low temperature rod 106 based on the output signal of the thermocouples 105. The temperature T2 at the contact portion between the heat conductive sheet S and the heat conductive sheet S is estimated. Subsequently, the calculation unit calculates the thermal resistance R of the thermally conductive sheet S based on the temperature difference between T1 and T2 and the amount of heat Q flowing through the thermally conductive sheet S.
Note that reference numerals 102 and 108 in FIG. 8 are heat insulating materials for effectively creating a temperature difference between both sides of the heat conductive sheet S, which is the object to be measured.

Although the thermal resistance of the thermally conductive sheet S can be measured as described above, instead of directly measuring the difference in surface temperature on both sides of the thermally conductive sheet S, the temperature is measured at a position away from the thermally conductive sheet S. Since the surface temperature was estimated based on the temperature gradient, it was difficult to obtain sufficient measurement accuracy.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a thermal resistance measuring device that can measure the thermal resistance of a measured object made of a planar body with higher accuracy. There is a particular thing.

The above problem is solved by the thermal resistance measuring device of the present invention, which is used to measure the thermal resistance of an object to be measured consisting of a planar body, in which one side of the object to be measured is measured. a heating body to heat, a first thin film thermocouple interposed between the object to be measured and the heating body and in contact with the object to be measured, and a position at a position different from a position at which the heating body heats the object to be measured; , a second thin film thermocouple in contact with the object to be measured and a high temperature side surface temperature are calculated based on the output signals of the first thin film thermocouple, and a low temperature side surface temperature is calculated based on the output signal of the second thin film thermocouple. The problem is solved by including a thermal resistance calculation processor that calculates the temperature and calculates the thermal resistance of the object to be measured based on the temperature difference between the high temperature side surface temperature and the low temperature side surface temperature.

According to the above configuration, the object to be measured is heated by the heating element, and the first thin film thermocouple is disposed between the heating element and the object in contact with the object to be measured. Further, a second thin film thermocouple is arranged so as to come into contact with the object to be measured at a position different from that of the heating body. Then, a temperature difference is calculated based on the output signals of the first thin film thermocouple and the second thin film thermocouple, and a thermal resistance of the object to be measured is calculated based on the temperature difference. As a result, the surface temperature can be measured with the first thin film thermocouple and the second thin film thermocouple in contact with the object to be measured, so the gradient temperature measured at a distance from the object can be Compared to the case where the surface temperature is estimated based on this, it is possible to improve the measurement accuracy.
In addition, by bringing the thin film thermocouple into contact with the object to be measured consisting of a planar body and measuring the surface temperature with the thin film thermocouple in surface contact with the object to be measured, the object to be measured consisting of a planar object can be measured. The surface temperature can be measured with high accuracy without deforming or damaging the surface of the substrate, thereby making it possible to improve the measurement accuracy of thermal resistance.

The heating body includes a high-temperature plate that comes into contact with the object to be measured, and a heater that heats the high-temperature plate, and the first thin film thermocouple is arranged between the high-temperature plate and the object to be measured. The second thin film thermocouple is sandwiched between the object to be measured and a low temperature plate disposed to face the high temperature plate with the object to be measured sandwiched therebetween. Then, it is suitable.
According to the above configuration, the first thin film thermocouple and the second thin film thermocouple can measure the surface temperature while being in surface contact with the measured object by being sandwiched between the measured object and the high temperature plate or the low temperature plate. can. Therefore, the surface temperature can be measured with high accuracy without deforming or damaging the surface of the object to be measured, which is a planar body, and thereby it is possible to improve the measurement accuracy of thermal resistance.

The thermal resistance measuring device also includes a base, a heat insulating material installed above the base to support the heating element, and a cooler installed above the low temperature plate to cool the low temperature plate. It is preferable to include a weighting mechanism that loads the low temperature plate toward the object to be measured via the cooler.
According to the above configuration, since the heating body is supported by the heat insulating material disposed above the base, the heat of the heater can be effectively transmitted to the object to be measured. The cold plate is also weighted by a weighting mechanism via the cooler. Thereby, the first thin-film thermocouple and the second thin-film thermocouple measure the surface temperature while being in surface contact with the object to be measured while being sandwiched between the object to be measured and the high-temperature plate or the low-temperature plate in a weighted state. Therefore, the surface temperature can be measured with high accuracy without deforming or damaging the surface of the object to be measured, which is a planar body, and thereby it is possible to improve the measurement accuracy of thermal resistance.

The thermal resistance measuring device includes a thickness measuring device that measures the thickness of the object to be measured, and a load measuring device that measures the load caused by the weighting mechanism, and the thermal resistance calculation processor is configured to measure the thickness of the object to be measured. It is preferable that the thickness outputted by the device and at least one of the load outputted by the load measuring device and the thermal resistance of the object to be measured are outputted in relation to each other.
According to the above configuration, it is possible to determine an appropriate load according to the thickness of the object to be measured, and to effectively apply weight to the object to be measured. Therefore, it is possible to measure thermal resistance with higher accuracy.

Further, it is preferable that the contact surfaces of the high temperature plate and the low temperature plate that contact the object to be measured have a surface roughness (Ra) of 0.022 μm or less.
According to the above configuration, it is possible to improve the adhesion between the object to be measured, which is a planar body, and the contact surfaces of the high-temperature plate and the low-temperature plate. Therefore, the formation of an air layer between the object to be measured and the contact surface is suppressed, and it becomes possible to improve the measurement accuracy of thermal resistance.

Further, it is preferable that each of the first thin film thermocouple and the second thin film thermocouple contact the object to be measured at mutually opposing positions on both sides of the object to be measured, which is made of the planar body.
According to the above configuration, it is possible to measure the thermal resistance to heat transmitted from one surface of the object to be measured made of a planar body to the other surface. Therefore, it is possible to measure the thermal resistance when a thermally conductive sheet, which is an object to be measured, is held between a heating element (for example, a power semiconductor element) and a heat dissipation member (for example, a heat sink).

Further, a plurality of first thin film thermocouples are disposed between the object to be measured and the heating body, and at a position facing the plurality of first thin film thermocouples with the object to be measured interposed therebetween. It is preferable that a plurality of the second thin film thermocouples are provided.
According to the above configuration, it is possible to measure the thermal resistance distribution of the object to be measured consisting of a planar body by the plurality of first thin film thermocouples and second thin film thermocouples arranged so as to face each other. .

Preferably, the second thin film thermocouple contacts the object to be measured on the same surface as the first thin film thermocouple of the object.
According to the above configuration, it is possible to measure the thermal resistance when heat is transferred along the surface of the object to be measured made of a planar body.

According to the thermal resistance measuring device of the present invention, it is possible to measure the thermal resistance of a measured object made of a planar body with higher accuracy.

1 is a schematic diagram of a thermal resistance measuring device according to an embodiment of the present invention. FIG. 2 is a schematic diagram of a thin film thermocouple. FIG. 2A is a sectional view taken along line AA in FIG. 2A. FIG. 3 is a diagram showing a state in which thin film thermocouples are arranged facing each other on both sides of a heat conductive sheet. It is a figure which shows the example of arrangement|positioning of the temperature measurement point of a thermally conductive sheet. FIG. 3 is a diagram showing the functional configuration of a thermal resistance calculation processor. It is a schematic diagram which shows the example of arrangement|positioning of the thin film thermocouple based on a modification. FIG. 3 is a schematic diagram of a thermal resistance measuring device according to a second embodiment. FIG. 2 is a diagram illustrating the measurement principle of a conventional thermal resistance measuring device.

Hereinafter, a thermal resistance measuring device 1 according to an embodiment (this embodiment) of the present invention will be described with reference to FIGS. 1 to 5. Note that the materials, arrangement, configuration, etc. described below do not limit the present invention, and can be variously modified within the scope of the spirit of the present invention.

The thermal resistance measuring device 1 of the present invention measures the surface temperature of the object to be measured with a pair of thin film thermocouples 16 arranged so as to be in contact with the object to be measured, which is a planar body, and thereby measures the temperature of the object to be measured with high accuracy. Used to measure resistance.
Here, the "planar body" may be a flexible sheet or a plate whose shape does not change. That is, a "planar object" refers to an object having a film, sheet, thin plate, or other planar form, regardless of thickness, flexibility, and material.

<Overall configuration of thermal resistance measuring device 1>
FIG. 1 is a schematic diagram of a thermal resistance measuring device 1 according to an embodiment. As shown in FIG. 1, the thermal resistance measuring device 1 has a frame body including a base 10, four columns 11 extending upward at the four corners of the base 10, and an upper plate 12 supported by the columns 11. have.

The heat conductive sheet S, which is the object to be measured, is placed inside the frame. The heat conductive sheet S is a heat transfer member used to transfer heat generated from a heating element to a heat radiating member or a cooling member. The thermally conductive sheet S is a resin sheet having high thermal conductivity and electrical insulation. The thermally conductive sheet S is, for example, a silicone sheet. The heat conductive sheet S may be a fluororesin sheet.

The thermally conductive sheet S is supported while being sandwiched between a heating body and a cooling body. The heating body mainly includes a heat insulating material 13, a heater 14, and a high temperature plate 15, and heats the lower surface of the heat conductive sheet S.
The heat insulating material 13 is a glass wool heat insulating material installed on the base 10. The heat insulating material 13 is used to support a heater 14, which will be described later, and to efficiently transmit heat generated by the heater 14 to the high temperature plate 15.

The heater 14 is a resistance heating element placed on the heat insulating material 13. To explain in detail, the heater 14 has an electrically insulating substrate and a metal foil placed on the substrate, and generates Joule heat by a current flowing through the metal foil. The metal foil has a pattern shape that spreads across a plane while meandering over the substrate. This allows the heater 14 to heat the high temperature plate 15 evenly and uniformly. The metal foil is stainless steel foil, which can be easily patterned, but is not limited thereto. Instead of the metal foil, a conductive wire made of nichrome wire or the like may be wired on the substrate. The heater 14 corresponds to a heater.

The high temperature plate 15 is an aluminum plate with excellent thermal conductivity and heat resistance. The high temperature plate 15 is heated by the heater 14 and plays the role of transmitting heat to the lower surface of the heat conductive sheet S. The high temperature plate 15 has a wider flat surface than the heat conductive sheet S, and can heat the heat conductive sheet S uniformly by covering the entire lower surface of the heat conductive sheet S. The high temperature plate 15 is not limited to an aluminum plate. Any plate-shaped body that can efficiently transmit the heat of the heater 14 to the heat conductive sheet S may be used, and it may be a plate made of metal other than aluminum or a plate made of ceramics having high thermal conductivity.

The high-temperature plate 15 has an upper surface that contacts the heat conductive sheet S subjected to a mirror finishing treatment, and has excellent flatness. Specifically, the upper surface of the high temperature plate 15 has a surface roughness (Ra) of 0.022 μm or less. Here, in this specification, the surface roughness (Ra) means the arithmetic mean roughness defined in JIS B 0601:2013. As described above, since the upper surface of the high-temperature plate 15 has excellent flatness, it is possible to improve the adhesion with the thermally conductive sheet S that comes into contact with the upper surface. Therefore, formation of an air layer between the upper surface and the heat conductive sheet S due to the unevenness formed on the upper surface of the high temperature plate 15 is suppressed. Thereby, the heat of the high-temperature plate 15 can be efficiently transferred to the heat conductive sheet S, and the measurement accuracy of the thermal resistance measuring device 1 can be improved. The upper surface of the high temperature plate 15 corresponds to a contact surface.
Note that the upper surface of the high-temperature plate 15 may be subjected to a polishing treatment to have excellent flatness due to the polishing treatment.

The cooling body mainly includes a cooler 18 and a low temperature plate 17, and cools the low temperature side of the heat conductive sheet S.
The cooler 18 is an aluminum block body in which a cooling liquid circulates. Specifically, the cooler 18 is formed such that a cooling liquid circulation path spreads out in a planar manner inside the cooler 18 . Thereby, it becomes possible to evenly and uniformly cool the low temperature plate 17, which will be described later. Coolant circulating inside the cooler 18 is supplied by a pump (not shown).

The low temperature plate 17 is an aluminum plate with excellent thermal conductivity and heat resistance. The low temperature plate 17 is cooled by the cooler 18 and plays the role of dissipating heat from the heat conductive sheet S. The low temperature plate 17 has a flat surface wider than the heat conductive sheet S, and by covering the entire upper surface of the heat conductive sheet S, the heat conductive sheet S can be cooled uniformly. The low temperature plate 17 may be a metal plate other than an aluminum plate or a ceramic plate having high thermal conductivity.

The lower surface of the low temperature plate 17 that contacts the heat conductive sheet S is mirror-finished and has excellent flatness. The lower surface of the low temperature plate 17 has a surface roughness (Ra) of 0.022 μm or less. Thereby, like the upper surface of the high temperature plate 15, it is possible to improve the adhesion with the heat conductive sheet S, and it is possible to improve the measurement accuracy of the thermal resistance measuring device 1. The upper surface of the low temperature plate 17 corresponds to a contact surface.

A weighting mechanism is disposed above the cooling body to load the cooling body downward, that is, toward the heat conductive sheet S. The weighting mechanism mainly includes an operating section 21, a weighting screw 20, and a load cell 19.
The operating section 21 is a rotary operating body that causes rotational movement to the weighted screw 20 . The outer periphery of the operating portion 21 is knurled. Thereby, when operating the operating section 21, it becomes possible to reliably hold and rotate the operating section 21 between the fingers.

The weighted screw 20 is a shaft member, and its outer peripheral surface is threaded. The weighting screw 20 passes through a through hole formed in the upper plate 12. The weighted screw 20 is threaded into a threaded groove formed on the inner circumferential surface of the through hole. Thereby, the weighting screw 20 converts the rotational movement of the operating part 21 into an up-and-down movement, and loads the above-mentioned cooling body toward the heat conductive sheet S side. Therefore, the thermally conductive sheet S can be held between the heating body and the cooling body with an appropriate clamping force, and it is possible to improve the measurement accuracy and reproducibility of thermal resistance.

The load cell 19 has a built-in strain sensor and can detect and output the strain caused by the load generated by the weighted screw 20. Thereby, it becomes possible to appropriately manage the clamping force by the heating body and the cooling body. The load cell 19 corresponds to a load measuring device.

The surface temperature on the high temperature side of the heat conductive sheet S heated by the heating body is measured using the high temperature side thin film thermocouple 16A. On the other hand, the surface temperature on the low temperature side of the heat conductive sheet S cooled by the cooling body is measured using the low temperature side thin film thermocouple 16B. The high temperature side thin film thermocouple 16A corresponds to a first thin film thermocouple, and the low temperature side thin film thermocouple 16B corresponds to a second thin film thermocouple.
Since the high-temperature side thin-film thermocouple 16A and the low-temperature side thin-film thermocouple 16B have the same shape, size, and configuration, in the following description, the high-temperature side thin-film thermocouple 16A and the low-temperature side thin-film thermocouple 16B will be referred to as the same. If there is no particular need to distinguish, it will be simply referred to as a "thin film thermocouple 16." The thin film thermocouple 16 will be described later with reference to FIGS. 2A and 2B.

The high temperature side thin film thermocouple 16A and the low temperature side thin film thermocouple 16B are electrically connected to the thermal resistance calculation processor 30. The thermal resistance calculation processor 30 calculates the surface temperature of the lower surface of the heat conductive sheet S (high temperature side surface temperature) based on the output signal of the high temperature side thin film thermocouple 16A. The thermal resistance calculation processor 30 also calculates the surface temperature of the upper surface of the heat conductive sheet S (low temperature side surface temperature) based on the output signal of the low temperature side thin film thermocouple 16B. Then, the thermal resistance calculation processor 30 calculates the temperature difference between the high temperature side surface temperature and the low temperature side surface temperature, and calculates the thermal resistance of the heat conductive sheet S based on the temperature difference. A method for calculating the thermal resistance will be described later with reference to FIG. 5.

<Thin film thermocouple 16>
Next, the thin film thermocouple 16 used to measure the surface temperature of the heat conductive sheet S will be explained.
2A and 2B are schematic diagrams of the thin film thermocouple 16. The thin film thermocouple 16 has a first conductive thin film 162 and a second conductive thin film 163 on a substrate 161, a temperature measuring junction 164 for measuring the temperature of the object to be measured at one end, and an open end at the other end. Connection ends 166 of each thin film pattern are formed.

The substrate 161 can be made of glass, film, metal, or the like. However, when the substrate 161 is made of a conductive material such as metal, it is necessary to form an insulating film such as SiO ₂ or Al ₂ O ₃ on the metal surface in advance and then form the thin film thermocouple 16 thereon. Therefore, films are preferred. The film can increase the strength of the substrate 161 due to its flexibility. More preferably, the substrate 161 is made of polyimide film. Polyimide film is suitable for thin film thermocouples because it can be bent, is difficult to break even when the substrate 161 is several tens of microns thick, and is easy to handle, and is relatively stable even at temperatures exceeding 200°C. This material is suitable as a substrate of 16.

The thickness of the substrate 161 is preferably 1 μm or more and 150 μm or less, more preferably 1 μm or more and 50 μm or less, particularly preferably 1 μm or more and 18 μm or less.

Combinations of different metals constituting the first conductive thin film 162 and the second conductive thin film 163 of the thin film thermocouple 16 include chromel-alumel, PtRh-Pt, chromel-constantan, nicrosil-nisyl, Cu-constantan, Fe- Constantan, Ir-IrRh, W-Re, Au-Pt, Pt-Pd, Bi-Sb, etc. can be used. In particular, it is preferable to use a combination of chromel and alumel, which can be used over a wide temperature range and has a linear relationship between temperature and thermoelectromotive force.

The thickness of the first conductive thin film 162 and the second conductive thin film 163 is preferably 10 nm or more and 1 μm or less, more preferably 100 nm or more and 700 nm or less, and more preferably 150 nm or more and 550 nm or less.

As a method for forming the first conductive thin film 162 and the second conductive thin film 163, a vacuum film forming method such as a sputtering method, an electron beam evaporation method, a heating evaporation method, a coating method, etc. can be used. Preferably, a vacuum film forming method is used, which allows a thinner and more uniform thin film to be formed. More preferably, a sputtering method is used, which has little difference in atomic composition from the vapor deposition material and can form a uniform film.

It is desirable that the thin film thermocouple 16 be covered with a protective film 165. This is because the protective film 165 not only enhances the environmental resistance of the thin film thermocouple 16 but also has the effect of preventing the occurrence of cracks that may occur when the thin film thermocouple 16 is deformed by external force. Applicable protective films 165 include an insulating film formed of SiO ₂ , Al ₂ O ₃ or the like by a vapor deposition method, a sputtering method, a dipping method, etc., a polyimide film formed by a screen printing method, or the like. Preferably, a polyimide film having high heat resistance, high chemical resistance, and high adhesiveness is used.

As shown in FIG. 2B, it is preferable that a reinforcing member 167 is provided at the connection end 166 of the substrate 161. The material of the reinforcing member 167 is not particularly limited, and for example, epoxy glass can be used. According to the reinforcing member 167, the strength of the thin film thermocouple 16 is improved, and the connectivity with a connector (not shown) is improved.

FIG. 3 shows a state in which a high temperature side thin film thermocouple 16A and a low temperature side thin film thermocouple 16B are brought into contact with the heat conductive sheet S. As shown in FIG. 3, a high temperature side thin film thermocouple 16A is disposed on the high temperature side of the heat conductive sheet S so as to be in surface contact therewith. On the other hand, a low temperature side thin film thermocouple 16B is disposed on the low temperature side of the heat conductive sheet S so as to be in surface contact therewith.
In this way, the surface temperature of the heat conductive sheet S can be measured with high accuracy by bringing the high temperature side thin film thermocouple 16A and the low temperature side thin film thermocouple 16B into surface contact with the heat conductive sheet S which is the object to be measured. It becomes possible to do so.

Here, the thickness dimension of the heat conductive sheet S is, for example, 1 mm. On the other hand, the thickness of the thin film thermocouple 16 is approximately 10 μm. Therefore, as described above, even if the heat conductive sheet S is sandwiched between the heating body and the cooling body and a load is applied by the loading mechanism, the heat conductive sheet S will not be deformed or damaged by the thin film thermocouple 16. It becomes possible to measure the surface temperature of the surface with high accuracy.

In addition, since surface temperature can be measured by simply bringing a pair of thin film thermocouples 16 into contact with the thermally conductive sheet S, the configuration of the thermal resistance measuring device 1 can be simplified and manufacturing costs can be reduced. becomes.

In FIG. 3, the thin film thermocouple 16 is shown disposed approximately at the center of the heat conductive sheet S to measure the surface temperature at the center of the heat conductive sheet S, but the present invention is not limited thereto. The thin film thermocouples 16 can measure the surface temperature of a temperature measuring point located at an arbitrary position on the heat conductive sheet S, and by bringing the plural thin film thermocouples 16 into contact with the heat conductive sheet S, The surface temperature of the temperature measurement point can be measured.

FIG. 4 shows an example of temperature measurement points M on the thermally conductive sheet S. As shown in FIG. 4, by positioning the temperature measuring contacts 164 of the thin film thermocouple 16 on both sides of an arbitrary temperature measuring point M of the heat conductive sheet S, the thermal resistance at an arbitrary position can be measured. Alternatively, a plurality of thin film thermocouples 16 may be brought into contact with the thermally conductive sheet S at the same time to simultaneously measure the thermal resistance at a plurality of temperature measurement points M. Thereby, it becomes possible to efficiently measure the thermal resistance distribution at the plurality of temperature measuring points M of the thermally conductive sheet S.

Although FIG. 4 shows an example in which the temperature measurement points M are arranged in a grid pattern on the heat conductive sheet S, the temperature measurement points are not limited to the arrangement shown in FIG. The temperature measurement points M may be arranged so as to radiate from the center of the heat conductive sheet S.

<Functional configuration of thermal resistance calculation processor>
Next, the functional configuration of the thermal resistance calculation processor 30 and the calculation process of thermal resistance by the thermal resistance calculation processor 30 will be explained.
FIG. 5 shows the functional configuration of the thermal resistance calculation processor 30. Thermal resistance calculation processor 30 includes a processor, volatile memory, and nonvolatile memory. The processor of the thermal resistance calculation processor 30 executes the program stored in the non-volatile memory, so that the thermal resistance calculation processor 30 receives the input reception section 31, the surface temperature measurement section 32, the heat flux measurement section 33, and the heat flux measurement section 33. It functions as a resistance measuring section 34 and an output section 35.

The input receiving unit 31 receives a user's operation input to the thermal resistance calculation processor 30. More specifically, the input receiving unit 31 receives input operations for measurement parameters necessary for measuring thermal resistance, measurement start operations for starting measurements, and output operations for outputting measurement results. The input reception unit 31 can receive input using a known input means such as a keyboard, a mouse, an operation button, a touch panel, or the like.

The measurement parameters include the amount of energy applied to the object to be measured (or the voltage applied to the heater 14 mentioned above and the current value flowing through the heater 14), the surface area of the object to be measured (or the width of the object to be measured) , length, and thickness dimensions).
Upon receiving the measurement start operation, the input receiving unit 31 controls the heating body to start heating. Further, the input receiving unit 31 causes the surface temperature measuring unit 32, the heat flux measuring unit 33, and the thermal resistance measuring unit 34 to start measurements after heating is started.

The surface temperature measuring section 32 acquires the output signal of the thin film thermocouple 16 and calculates the surface temperature of the object to be measured based on the output signal. More specifically, the surface temperature measurement unit 32 measures the temperature at the temperature measurement junction 164 based on the output voltage difference between the first conductive thin film 162 and the second conductive thin film 163 and a predetermined calculation formula. Calculate. The surface temperature measuring section 32 outputs the measured surface temperature to a thermal resistance measuring section 34, which will be described later.

The heat flux measurement unit 33 calculates the heat flux passing through the object to be measured. More specifically, the heat flux measurement unit 33 calculates the heat flux q by the following equation (1), where Q is the amount of heat given to the object to be measured from the heating body, and a is the surface area of the object to be measured. calculate. The heat flux measuring section 33 outputs the calculated heat flux to a thermal resistance measuring section 34, which will be described later.
q=Q/a (1)
Here, Q is the amount of energy given to the heat conductive sheet S by the heater 14 made of a resistance heating element, and is calculated based on the voltage value applied to the resistance heating element and the current value flowing through the resistance heating element. can do. The voltage value applied to the resistive heating element and the current value flowing through the resistive heating element are inputted via the input receiving section 31 described above.
The surface area a of the object to be measured can be calculated using the following equation (2) based on the width W and length L of the thermally conductive sheet S. The width W and length L of the thermally conductive sheet S are input via the input receiving section 31 described above.
a=W×L (2)

The thermal resistance measurement section 34 determines the temperature of the object to be measured based on the temperature difference between the high temperature side surface temperature Th and the low temperature side surface temperature Tl of the object measured by the surface temperature measurement section 32 and the heat flux measured by the heat flux measurement section 33. Calculate the thermal resistance of the measured object. More specifically, the thermal resistance measurement unit 34 calculates the thermal resistance R using the following formula (3), where the temperature difference between the surface temperatures of the object to be measured is ΔT (=Th - Tl) and the heat flux is q. . The thermal resistance measurement section 34 outputs the calculated thermal resistance to an output section 35, which will be described later.
R=ΔT/q (3)
Here, the temperature difference ΔT is a temperature difference obtained by subtracting the low temperature side surface temperature Tl from the high temperature side surface temperature Th of the thermally conductive sheet S, and is calculated based on the output value of the surface temperature measuring section 32 described above. can do.
The heat flux q is a heat flux passing through the thermally conductive sheet S, and is a value calculated by the heat flux measurement unit 33 based on equation (1).

The thermal resistance measurement unit 34 monitors the temperature difference ΔT between the high temperature side surface temperature and the low temperature side surface temperature of the object measured by the surface temperature measurement unit 32, and determines whether the temperature difference ΔT satisfies a predetermined convergence condition. After determining that the convergence condition is satisfied, the thermal resistance of the object to be measured is measured. This makes it possible to improve the measurement accuracy and reliability of thermal resistance.

The output unit 35 outputs the thermal resistance calculated by the thermal resistance measurement unit 34. More specifically, the output unit 35 can display and output the thermal resistance to a display device (not shown), and can also output the thermal resistance to a storage device (not shown) consisting of an HDD (Hard Disk Drive) or an SSD (Solid State Drive). Can be saved and output. Further, the output unit 35 may transmit and output the thermal resistance to an external information communication terminal connected via a communication line (not shown).

As described above with reference to FIG. 4, when the thermal resistance at a plurality of temperature measurement points M is measured using a plurality of thin film thermocouples 16, the output unit 35 outputs a thermal resistance distribution diagram. Good too. This makes it possible to visually recognize the degree of variation in the thermal resistance of the object to be measured.

Although the thermal resistance measuring device 1 according to one embodiment of the present invention has been described, the above-described embodiment is only an example for facilitating understanding of the present invention, and does not limit the present invention. That is, the present invention can be modified and improved without departing from the spirit thereof, and it goes without saying that the present invention includes equivalents thereof.

<Modified example>
In the embodiment described above, the high temperature side thin film thermocouple 16A and the low temperature side thin film thermocouple 16B are arranged to face each other above and below the heat conductive sheet S, and the thermal resistance between the upper surface and the lower surface is measured. Although described above, the invention is not limited thereto. The high temperature side thin film thermocouple 16A and the low temperature side thin film thermocouple 16B may be brought into contact with the same surface, either the upper surface or the lower surface, and the thermal resistance at different positions within the same surface may be measured.

FIG. 6 is a schematic diagram showing an arrangement example of a thermal resistance measuring device 201 and a thin film thermocouple 216 according to a modification. The thermally conductive sheet S, which is the object to be measured, is supported while being sandwiched between the heating body, the cooling body, and the heat insulating material 213. The heating body has a heater 214 as a main component. The heater 214 is a resistance heating element made of a planar body, similar to the embodiment described above. The heater 214 directly contacts the heat conductive sheet S without using the high temperature plate 15 to heat the heat conductive sheet S.

The cooling body mainly includes a cooler (not shown) and a low temperature plate 217 that comes into contact with the low temperature side of the heat conductive sheet S at a position different from the position where the heater 214 heats the heat conductive sheet S. ing. The cold plates 217 are disposed on both sides of the heater 214 at equal predetermined intervals.

The insulation material 213 is a glass wool insulation material. The heat insulating material 213 covers the upper surface of the heat conductive sheet S, and prevents the heat of the heater 14 from escaping from the upper surface of the heat conductive sheet S.

The surface temperature on the high temperature side of the heat conductive sheet S heated by the heater 214 is measured using the high temperature side thin film thermocouple 216A. On the other hand, the surface temperature on the low temperature side of the heat conductive sheet S cooled by the cooling body is measured using the low temperature side thin film thermocouple 216B.

The heat flux measurement unit 33 calculates the heat flux (arrow A) along the surface of the heat conductive sheet S using the above-mentioned equation (1).
At this time, the surface area a can be calculated by the following equation (4) based on the length L (dimension in the depth direction in FIG. 6) and thickness D of the heat conductive sheet S. The length L and thickness D of the thermally conductive sheet S are input via the input receiving section 31 described above.
a=L×D (4)
The thermal resistance measurement unit 34 calculates the thermal resistance of the thermally conductive sheet S using the above-mentioned equation (3).

As described above, by bringing the low temperature side thin film thermocouple 216B into contact with the heat conductive sheet S at a position different from the heating position of the heater 214, it becomes possible to easily measure the thermal resistance at various positions. .

In the above-described embodiment, the case where the object to be measured is the thermally conductive sheet S made of a silicone sheet having electrical insulation properties has been described as an example, but the present invention is not limited thereto. The present invention can be applied to a conductive planar object as an object to be measured and its thermal resistance measured. Further, the present invention can be applied to use a metal plate as the object to be measured and measure the thermal resistance of the metal plate.

<Second embodiment>
Next, a thermal resistance measuring device 301 according to a second embodiment will be described.
FIG. 7 is a schematic diagram of a thermal resistance measuring device 301 according to the second embodiment. The thermal resistance measuring device 301 according to the second embodiment includes a dial gauge 322 that can measure the thickness of the thermally conductive sheet S.
The thermal resistance calculation processor 330 acquires the thickness of the thermally conductive sheet S output by the dial gauge 322. Further, the thermal resistance calculation processor 330 obtains the load of the weighted screw 20 output by the load cell 19. Then, the thermal resistance calculation processor 330 associates the thickness, the load, and the thermal resistance calculated by the thermal resistance calculation processor 330 with each other, and displays and outputs them. Therefore, according to the thermal resistance measuring device 301 according to the second embodiment, an appropriate load can be determined according to the thickness of the thermally conductive sheet S, and the thermally conductive sheet S can be effectively loaded. Therefore, it is possible to measure thermal resistance with higher accuracy.

As shown in FIG. 7, the dial gauge 322 is fixed to the cooler 18. Furthermore, a measurement table 323 is fixed on the base 310. Therefore, the thickness of the thermally conductive sheet S is measured by placing the thermally conductive sheet S, which is the object to be measured, on the measurement table 323 and bringing the lower end of the spindle 322B of the dial gauge 322 into contact with the upper surface of the thermally conductive sheet S. It can be measured. To explain in more detail, the spindle 322B is attached to the dial gauge main body 322A so as to be movable up and down. The vertical movement of the spindle 322B is converted into a measured value (thickness) by a detection mechanism disposed inside the dial gauge main body 322A. The measured value is output to the display 322C and also to the thermal resistance calculation processor 330. The dial gauge 322 corresponds to a thickness measuring device.

The thermal resistance calculation processor 330 acquires the thickness of the thermally conductive sheet S output by the dial gauge 322. Further, the thermal resistance calculation processor 330 obtains the load of the weighted screw 20 output by the load cell 19.
The output unit 35 of the thermal resistance calculation processor 330 outputs the thickness of the thermally conductive sheet S, the load of the weighted screw 20, and the thermal resistance of the thermally conductive sheet S in relation to each other. Specifically, the output unit 35 can display and output the thickness, load, and thermal resistance simultaneously to a display device (not shown), and can also save and output the information to a storage device (not shown). . Further, the output unit 35 may transmit and output the thickness, load, and thermal resistance to an external information communication terminal connected via a communication line. This makes it possible to grasp the relationship between the thickness, load, and thermal resistance of the heat conductive sheet S, and to grasp the appropriate load according to the thickness dimension of the heat conductive sheet S, making it possible to effectively control the heat conductive sheet S. can be weighted accordingly. Therefore, it is possible to measure thermal resistance with higher accuracy.

Although the thermal resistance measuring device 301 according to the second embodiment has been described above as including the dial gauge 322 in order to measure the thickness dimension of the thermally conductive sheet S, the present invention is not limited to this. It is only necessary to be able to obtain the thickness dimension of the thermally conductive sheet S with sufficient accuracy, and the thermal resistance measuring device 301 may employ a thickness measuring device using ultrasonic waves instead of the dial gauge 322.
Further, although the dial gauge 322 has been described as being fixed to the cooler 18, the present invention is not limited thereto. The dial gauge 322 may be fixed to the support column 11 or may be fixed to the base 310.

Furthermore, although the thermal resistance calculation processor 330 according to the second embodiment has been described as directly acquiring the thickness of the thermally conductive sheet S output from the dial gauge 322 and the load of the weighted screw 20 output from the load cell 19, this but not limited to. The user who has read the measured values of the dial gauge 322 and the load cell 19 may obtain the thickness of the thermally conductive sheet S and the load of the weighted screw 20 by inputting the read values into the thermal resistance calculation processor 330. good.

1 Thermal resistance measuring device 10 Base 11 Support column 12 Upper plate 13 Heat insulating material 14 Heater (heating body, heater)
15 High temperature plate (heating body)
16 Thin film thermocouple 16A High temperature side thin film thermocouple (first thin film thermocouple)
16B Low temperature side thin film thermocouple (second thin film thermocouple)
161 Substrate 162 First conductive thin film 163 Second conductive thin film 164 Temperature measuring contact 165 Protective film 166 Connection end 167 Reinforcement member 17 Low temperature plate 18 Cooler 19 Load cell (load measuring device)
20 Weighted screw 21 Operation unit 30 Thermal resistance calculation processor 31 Input reception unit 32 Surface temperature measurement unit 33 Heat flux measurement unit 34 Thermal resistance measurement unit 35 Output unit 101 Thermal resistance measurement device 102 Insulation material 103 Heater 104 High temperature rod 105A No. First high temperature thermocouple 105B Second high temperature thermocouple 105C Third high temperature thermocouple 105D Third low temperature thermocouple 105E Second low temperature thermocouple 105F First low temperature thermocouple 106 Low temperature rod 107 Cooler 108 Insulating material 201 Thermal resistance measuring device 213 Heat insulation Material 214 Heater 216 Thin film thermocouple (heating body, heater)
216A High temperature side thin film thermocouple (first thin film thermocouple)
216B Low temperature side thin film thermocouple (second thin film thermocouple)
217 Low temperature plate 301 Thermal resistance measuring device 310 Base 322 Dial gauge (thickness measuring device)
322A Dial gauge body 322B Spindle 322C Display 323 Measurement table 330 Thermal resistance calculation processor M Temperature measurement point S Thermal conductive sheet (object to be measured)

Claims (8)

A thermal resistance measuring device used to measure the thermal resistance of a measured object consisting of a planar body,
a heating element that heats one surface of the object to be measured;
a first thin film thermocouple interposed between the object to be measured and the heating body and in contact with the object to be measured;
a second thin film thermocouple that comes into contact with the object to be measured at a position different from the position where the heating body heats the object to be measured;
A high temperature side surface temperature is calculated based on the output signal of the first thin film thermocouple, a low temperature side surface temperature is calculated based on the output signal of the second thin film thermocouple, and the high temperature side surface temperature and the low temperature side surface temperature are calculated. A thermal resistance measuring device comprising: a thermal resistance calculation processor that calculates the thermal resistance of the object to be measured based on a temperature difference. The heating body includes a high temperature plate that comes into contact with the object to be measured, and a heater that heats the high temperature plate,
The first thin film thermocouple is sandwiched between the high temperature plate and the object to be measured,
2. The second thin film thermocouple is interposed between the object to be measured and a low-temperature plate disposed to face the high-temperature plate with the object to be measured interposed therebetween. 1. The thermal resistance measuring device according to 1. The thermal resistance measuring device includes:
The base and
a heat insulating material installed above the base and supporting the heating body;
a cooler mounted above the cold plate to cool the cold plate;
3. The thermal resistance measuring device according to claim 2, further comprising a weighting mechanism that loads the cold plate toward the object to be measured via the cooler. The thermal resistance measuring device includes a thickness measuring device that measures the thickness of the object to be measured, and a load measuring device that measures the load caused by the weighting mechanism,
The thermal resistance calculation processor is characterized in that the thickness outputted by the thickness measuring device, and at least one of the load outputted by the load measuring device and the thermal resistance of the object to be measured are correlated and outputted. The thermal resistance measuring device according to claim 3. The thermal resistance measuring device according to claim 3, wherein the contact surfaces of the high temperature plate and the low temperature plate that contact the object to be measured have a surface roughness (Ra) of 0.022 μm or less. 1 . The first thin film thermocouple and the second thin film thermocouple are each in contact with the object to be measured at mutually opposing positions on both surfaces of the object to be measured made of the planar body. Or the thermal resistance measuring device according to claim 2. A plurality of the first thin film thermocouples are disposed between the object to be measured and the heating body,
The thermocouple according to claim 1 or 2, wherein a plurality of the second thin film thermocouples are arranged at positions facing the plurality of first thin film thermocouples with the object to be measured interposed therebetween. Resistance measuring device. The thermal resistance measuring device according to claim 1, wherein the second thin film thermocouple contacts the object to be measured on the same surface as the surface of the object to be measured that the first thin film thermocouple contacts. .

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