A method for measuring thermal conductivity and thermal resistance of materials

Abstract

A method for measuring thermal conductivity and thermal resistance of a material relates to the field of semiconductor technology. A material to be tested is placed between two PADs at the bottom of two power semiconductor devices to form a sandwich structure of the power semiconductor device, the material to be tested, and the power semiconductor device. The coefficient K1 of the relationship curve between the cross-voltage VF and the temperature T of the semiconductor device under the condition of the detection current I1 is measured; the cross-voltage VF1 of the semiconductor device under the condition of the detection current I1 under the condition of 25°C is detected; according to Tjx=25°C+(VFx‑VF1)*K1, the corresponding junction temperature Tjx of the semiconductor device under the cross-voltage VFX is obtained; the cross-voltage VF2 of the lower semiconductor device under the condition of the detection current I1 is detected; the cross-voltage VF3 of the upper semiconductor device under the condition of the detection current I1 is detected, and the junction temperature Tj1 of the lower semiconductor device and the junction temperature Tj2 of the upper semiconductor device are obtained, and finally the thermal conductivity and thermal resistance of the material to be tested are calculated. The test method is simple and low-cost, and can be widely used in the measurement of thermal conductivity and thermal resistance of various materials.

Description

Technical Field

[0001] The invention relates to the field of semiconductor technology, and in particular to a method for measuring thermal conductivity and thermal resistance of a material. Background Art

[0002] The thermal conductivity and thermal resistance of materials are one of the important properties of the materials themselves. There are currently many methods for measuring the thermal conductivity and thermal resistance of materials. Most of these methods are targeted at specific materials and require special testing instruments and testing environments. They are costly and have low accuracy. Therefore, it is of great significance to develop a universal method for measuring the thermal conductivity and thermal resistance of materials.

[0003] In the existing patent literature, for example, an invention patent entitled "A method for measuring the thermal resistance of an IGBT junction to case" was published on June 11, 2014, with the application publication number CN103852483 A; comprising: providing a first IGBT to be tested, the first IGBT to be tested comprising: a packaged chip, a packaged shell and a heat sink; providing a second IGBT to be tested, the second IGBT to be tested The invention comprises: a packaged chip, a package shell, a heat sink and a heat conducting layer between the package shell and the heat sink, wherein the thermal conductivity of the heat conducting layer is greater than the thermal conductivity of air; under the same measurement conditions, a preset heating power is applied to the first IGBT to be tested and the second IGBT to be tested respectively, and the junction temperature curves of the first IGBT to be tested and the second IGBT to be tested under the heating power are measured; according to the junction temperature curves of the first IGBT to be tested and the second IGBT to be tested under the heating power, the transient thermal impedance curves or structure function curves of the first IGBT to be tested and the second IGBT to be tested are obtained; according to the transient thermal impedance curves or structure function curves of the first IGBT to be tested and the second IGBT to be tested, the junction-to-shell thermal resistance of the first IGBT to be tested is obtained, thereby improving the accuracy of the junction-to-shell thermal resistance measurement results. The patent adopts the principle of the double interface separation method to improve the test accuracy of the thermal resistance, but it can only measure the junction-to-shell thermal resistance of the IGBT, and is not suitable for the measurement of the thermal resistance of other powdered materials, semi-solid materials, and solid materials, and the measurement object is single.

[0004] In the existing patent literature, for example, an invention patent for "a method for measuring the thermal resistance of LED lamps" published on March 11, 2015, with the application publication number: CN104407280A; first, the LED lamp is placed in a constant temperature box and a constant voltage is used to power the LED lamp; second, the voltage drop of the LED lamp at different temperatures is measured to calculate the temperature coefficient K; then, the voltage drop of the LED lamp under the input electric power heating state is measured; and finally, the thermal resistance is calculated. This patent reduces the complexity of the thermal resistance test of LED lamps, but it can only test the thermal resistance of LED lamps, and is not suitable for the measurement of the thermal resistance of other powdered materials, semi-solid materials, and solid materials, and the measurement object is single.

[0005] In the existing patent literature, for example, a "Method for Testing Thermal Resistance and Thermal Conductivity of Materials" published on March 22, 2024 has an application publication number of: CN114544699B; it includes: arranging the material to be tested on a constant temperature heat sink; mounting a MOSFET power device on the material to be tested; causing the MOSFET power device to heat up until the heat flow transmission path reaches thermal equilibrium, and using a thermal resistance testing device to record a first heating curve of the voltage of the MOSFET power device changing with time; removing the material to be tested, and mounting the MOSFET power device on a constant temperature heat sink; causing the MOSFET power device to heat up until the heat flow transmission path reaches thermal equilibrium, and using a thermal resistance testing device to record a second heating curve of the voltage of the MOSFET power device changing with temperature; calculating the thermal resistance of the material to be tested based on the first heating curve and the second heating curve fitting; and determining the thermal conductivity of the material to be tested based on the thermal resistance. This patent expands the scope of materials to be tested, not just a single device, but the test steps are complicated. It is necessary to measure the first and second heating curves of the voltage change over time of the MOSFET power device when the material to be tested is arranged on a constant temperature heat sink and when the material to be tested is removed from the constant temperature heat sink. A constant temperature heat sink is required as an auxiliary equipment, which also increases the cost of the test. Summary of the invention

[0006] In view of the above problems, the present invention provides a method for measuring thermal conductivity and thermal resistance of materials and a test circuit thereof, which is generally applicable to the measurement of thermal conductivity and thermal resistance of various materials such as solid, powder, semi-solid, etc., and has a simple test method and low cost.

[0007] The technical solution of the present invention is:

[0008] A method for measuring thermal conductivity and thermal resistance of a material comprises the following steps:

[0009] Step S100, placing the semiconductor device in a high and low temperature box, measuring the relationship curve coefficient K1 between the cross voltage VF and the temperature T of the semiconductor device under the condition of the detection current I1, that is, K1=(VFx-VFy) / (Tx-Ty), VFx and VFy are the cross voltages of the semiconductor device under the conditions of temperature Tx and Ty respectively;

[0010] Step S200, using a thermal resistance tester to measure the thermal resistance RTHJC from the chip PN junction inside the semiconductor device to the bottom PAD;

[0011] Step S300, placing the material to be tested between a pair of PADs of semiconductor devices;

[0012] Step S400, detecting the cross voltage VF1 of the semiconductor device under the condition of 25°C (25°C is used as the reference junction temperature) under the condition of detecting the current I1; according to Tjx=25°C+(VFx-VF1)*K1, obtaining the cross voltage VFX The corresponding junction temperature is Tjx; VF X is the voltage across the semiconductor device under the condition of detection current I1, VF1 is the voltage across the semiconductor device at 25 degrees Celsius, where VF X is the voltage across the line at any other degree Celsius;

[0013] Step S500, as Figure 2 As shown, a heating power P is applied to the semiconductor device below;

[0014] Detecting the cross voltage VF2 of the lower semiconductor device under the condition of the detection current I1;

[0015] Detecting a voltage VF3 across the upper semiconductor device under a detection current I1 condition;

[0016] Step S600, substitute the cross voltage VF2 and the cross voltage VF3 with the cross voltage VF1 into Tjx=25℃+(VFx-VF1)*K1 respectively, and obtain the junction temperature Tj1 of the lower semiconductor device and the junction temperature Tj2 of the upper semiconductor device, Tj1=25℃+(VF2-VF1)*K1, Tj2=25℃+(VF3-VF1)*K1;

[0017] Step S700, calculating the thermal resistance RTHJ1J2 from the PN junction of the chip inside the lower semiconductor device to the junction of the upper semiconductor device = (Tj1- Tj2) / P;

[0018] Step S800, calculating the thermal resistance RTH=RTHJ1J2-2RTHJC of the material to be tested, and the thermal conductivity λ=L / (RTH*S) of the material to be tested.

[0019] Specifically, step S100 includes:

[0020] Step S110, placing the semiconductor device in a high and low temperature box, and connecting the semiconductor device and a semiconductor device electrical parameter tester using a test lead to form a loop;

[0021] Step S120, setting the detection current I1, testing the cross voltage VF at intervals of n°C within the range of 25-175°C, and obtaining the relationship curve coefficient K1 between the cross voltage VF and the temperature T.

[0022] Specifically, step S300 includes:

[0023] Step S310, facing the bottom PAD of the first semiconductor device upward, setting the thickness L and contact area S of the material to be tested, placing the material to be tested on the bottom PAD of the first semiconductor device, ensuring that the lower surface of the material to be tested is horizontal and in close contact with the bottom PAD, the contact area S is equal to the bottom PAD area of ​​the device, and the thickness L is set to 10-100um to ensure the test accuracy;

[0024] Step S320, the second upper semiconductor device is placed with the bottom PAD facing downwards, covering the material to be tested, to ensure that the upper surface of the material to be tested is level and in close contact with the bottom PAD of the device.

[0025] Specifically, step S400 includes:

[0026] Step S410, using a test wire to connect the semiconductor device and the semiconductor device electrical parameter tester to form a loop, setting the detection current to I1, and obtaining the cross voltage VF1 of the semiconductor device under the detection current I1 at 25°C.

[0027] Specifically, step S500 includes:

[0028] Step S510, using a test wire to connect a pair of semiconductor devices and a semiconductor device electrical parameter tester to form a loop, and setting a detection current I1;

[0029] Step S520, using a test wire to connect the semiconductor device below and the constant current source generator to form a loop, and setting a heating power P;

[0030] Step S530, applying heating power P to the lower semiconductor device until a thermal steady state is reached;

[0031] Step S540 , turning on the semiconductor device electrical parameter tester to detect the cross voltage VF2 of the lower semiconductor device under the condition of the detection current I1 ; and detecting the cross voltage VF3 of the upper semiconductor device under the condition of the detection current I1 .

[0032] Specifically, the semiconductor device package type has a PAD metal at the bottom, and the PAD metal is located within the package body, such as DFN series package, LEPAK series package, TOLL series package, etc. The heat of the PAD metal at the bottom of the two semiconductor devices is only transferred through the material to be tested.

[0033] Specifically, the upper and lower surfaces of the material to be tested are level, ensuring close contact with the PADs at the bottom of the two semiconductor devices. The material to be tested can be in various forms such as solid, powder, semi-solid, etc.

[0034] Beneficial effects of the present invention:

[0035] The thermal conductivity and thermal resistance of materials are one of the important properties of the materials themselves. Currently, there are many methods for measuring the thermal conductivity and thermal resistance of materials. Most of these methods are targeted at specific materials, require special testing instruments and testing environments, are costly and have low accuracy. Therefore, it is of great significance to develop a universal method for measuring the thermal conductivity and thermal resistance of materials. The present invention utilizes two power semiconductor devices, places the material to be tested between the PADs at the bottom of the two power semiconductor devices, forms a sandwich structure of the power semiconductor device, the material to be tested, and the power semiconductor device, and calculates the thermal conductivity and thermal resistance of the material to be tested by measuring the junction-to-junction thermal resistance of the upper and lower power semiconductors. It is generally applicable to the measurement of thermal conductivity and thermal resistance of various materials such as solid, powder, and semi-solid. The test method is simple and low-cost, and can be widely used in the measurement of thermal conductivity and thermal resistance of various materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a flow chart of the testing method of the present invention;

[0037] Figure 2 It is a schematic diagram of the test structure of the present invention;

[0038] In the figure, 1 is a semiconductor device, 2 is a material to be tested, 3 is an electrical parameter tester for a semiconductor device, and 4 is a constant current source generator. DETAILED DESCRIPTION

[0039] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0040] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] The present invention is described below with reference to FIGS. 1-2 ;

[0042] A method for measuring thermal conductivity and thermal resistance of a material and a test circuit thereof, comprising the following steps:

[0043] Step S100, placing the semiconductor device 1 in a high and low temperature box, and measuring the relationship curve coefficient K1 between the voltage VF and the temperature T of the semiconductor device 1 under the condition of the detection current I1;

[0044] Step S110, placing the semiconductor device 1 in a high and low temperature box, and connecting the semiconductor device 1 and the semiconductor device electrical parameter tester 3 using a test wire to form a loop;

[0045] Step S120, setting the detection current I1, testing the cross voltage VF at intervals of n°C within the range of 25-175°C, and obtaining the relationship curve coefficient K1 between the cross voltage VF and the temperature T, K1=(VFx-VFy) / (Tx-Ty), VFx, VFy are the cross voltages of the semiconductor device 1 under the temperature conditions of Tx, Ty respectively;

[0046] Accordingly, the semiconductor device 1 may be a diode, MOSFET, IGBT or other device, and the package type is a package with bottom PAD metal, such as DFN series package, LEPAK series package, TOLL series package, etc., within the range of 25-175°C, the interval temperature n depends on the test accuracy and test efficiency, the smaller n is, the higher the test accuracy and the longer the test time, and the detection current I1 generally takes a small current in the range of 1-100mA;

[0047] In this embodiment, a diode is used as the semiconductor device 1, a LEPAK33 package is adopted, n is set to 25, the test accuracy and test efficiency are guaranteed, the detection current I1 is set to 10mA, and K1=-2mV / °C is obtained.

[0048] Step S200, using a thermal resistance tester to measure the thermal resistance RTHJC from the chip PN junction inside the semiconductor device 1 to the bottom PAD;

[0049] Accordingly, the thermal resistance RTHJC from the internal chip PN junction to the bottom PAD of the semiconductor device 1 is measured using a T3test thermal resistance tester;

[0050] In this embodiment, the thermal resistance RTHJC from the internal chip PN junction to the bottom PAD of the diode is measured using a T3test thermal resistance tester, which is 2°C / W.

[0051] Step S300, placing the material 2 to be tested between a pair of PADs of the semiconductor device 1;

[0052] Step S310, the bottom PAD of the first semiconductor device 1 is facing upward, the thickness L and the contact area S of the material 2 to be tested are set, and the material 2 to be tested is placed on the bottom PAD of the device, ensuring that the lower surface of the material 2 to be tested is horizontal and in close contact with the bottom PAD of the device, the contact area S is equal to the area of ​​the bottom PAD of the device, and the thickness L is set to 10-100um to ensure the test accuracy;

[0053] Step S320, place the second semiconductor device 1 with the bottom PAD facing downwards, covering the material 2 to be tested, ensuring that the upper surface of the material 2 to be tested is level and in close contact with the bottom PAD of the device;

[0054] Correspondingly, the contact area S of the material to be tested 2 is equal to the PAD area at the bottom of the device, and the thickness L is set to 10-100um, ensuring that all the heat of the PAD at the bottom of the semiconductor device 1 below is transferred to the PAD at the bottom of the semiconductor device 1 above through the material to be tested 2;

[0055] In this embodiment, the PAD area at the bottom of the diode is 1mm*1mm, solder paste is selected as the material to be tested 2, and the area S of the solder paste is 1mm 2 , thickness L is 20um.

[0056] Step S400, detecting the cross voltage VF1 of the semiconductor device 1 under the condition of the detection current I1 at 25°C; according to Tjx=25°C+(VFx-VF1)*K1, obtaining the cross voltage VF X The following corresponds to the junction temperature Tjx;

[0057] Step S410, using a test wire to connect the semiconductor device 1 and the semiconductor device electrical parameter tester 3 to form a loop, and setting the detection current to I1;

[0058] Step S420, detecting the cross voltage VF1 of the semiconductor device 1 at 25°C, 25°C is used as the reference junction temperature, and detecting the cross voltage VFx of the semiconductor device 1 under the condition of the detection current I1 can obtain the corresponding junction temperature Tjx, Tjx=25°C+(VFx-VF1)*K1, VF X is the voltage across the semiconductor device under the condition of detection current I1, VF1 is the voltage across the semiconductor device at 25 degrees Celsius, where VF X is the voltage across the line at any other degree Celsius;

[0059] Correspondingly, the detection current I1 is generally a small current in the range of 1-100mA;

[0060] In this embodiment, the detection current I1 is set to 10 mA, and the VF1 of the diode is obtained to be 0.4 V at 25° C.

[0061] Step S500, as Figure 2 As shown, a heating power P is applied to the semiconductor device 1 below, and a cross voltage VF2 of the semiconductor device 1 below is detected under the condition of a detection current I1;

[0062] Detecting the cross voltage VF3 of the upper semiconductor device 1 under the condition of the detection current I1;

[0063] Step S510, using a test wire to connect two semiconductor devices 1 and a semiconductor device electrical parameter tester 3 to form a loop, and setting a detection current I1;

[0064] Step S520, using a test wire to connect the lower semiconductor device 1 and the constant current source generator 4 to form a loop, and setting the heating power P;

[0065] Step S530, applying heating power P to the lower semiconductor device 1 until a thermal steady state is reached;

[0066] Step S540, turning on the semiconductor device electrical parameter tester 3, detecting the cross voltage VF2 of the lower semiconductor device 1 under the condition of the detection current I1, and the cross voltage VF3 of the upper semiconductor device 1 under the condition of the detection current I1;

[0067] Accordingly, P must ensure that the device is not damaged, and the range is 1-100W;

[0068] In this embodiment, P is set to 3W. After reaching thermal steady state, the cross-voltage VF2 of the lower diode under the detection current I1 condition is 0.16V, and the cross-voltage VF3 of the upper diode under the detection current I1 condition is 0.186V.

[0069] Step S600, substitute VF2 and VF3 with VF1 into Tjx=25℃+(VFx-VF1)*K1 respectively, and obtain the junction temperature Tj1 of the lower semiconductor device 1 and the junction temperature Tj2 of the upper semiconductor device 1, Tj1=25℃+(VF2-VF1)*K1, Tj2=25℃+(VF3-VF1)*K1;

[0070] Correspondingly, VF2 and VF3 are substituted with VF1 into Tjx=25℃+(VFx-VF1)*K1 to obtain the junction temperature Tj1 of the lower semiconductor device 1 and the junction temperature Tj2 of the upper semiconductor device 1, Tj1=25℃+(VF2-VF1)*K1, Tj2=25℃+(VF3-VF1)*K1;

[0071] In this embodiment, the junction temperature Tj of the lower diode is obtained to be 145°C, and the junction temperature of the upper diode is obtained to be 132°C.

[0072] Step S700, calculating the thermal resistance RTHJ1J2=(Tj1- Tj2) / P from the internal chip PN junction of the lower semiconductor device 1 to the internal chip PN junction of the upper semiconductor device 1;

[0073] Correspondingly, the thermal resistance RTHJ1J2 from the internal chip PN junction of the lower semiconductor device 1 to the internal chip PN junction of the upper semiconductor device 1 = (Tj1- Tj2) / P;

[0074] In this embodiment, the heat generation power P of the lower diode is 3W, and the thermal resistance RTHJ1J2 from the internal chip PN junction of the lower semiconductor device 1 to the internal chip PN junction of the upper semiconductor device 1 is (Tj1-Tj2) / P=4.33°C / W.

[0075] Step S800, calculating the thermal resistance RTH of the material 2 to be tested = RTHJ1J2-2RTHJC, and the thermal conductivity λ of the material 2 to be tested = L / (RTH*S);

[0076] Correspondingly, the thermal resistance RTH of the material to be tested = RTHJ1J2-2RTHJC, and the thermal conductivity λ of the material to be tested = L / (RTH*S);

[0077] In this embodiment, the thermal resistance of the solder paste RTH= RTHJ1J2-2RTHJC=0.33°C / W, and the thermal conductivity λ=L / (RTH*S)=60.6 W / m.°C.

[0078] Regarding the contents disclosed in this case, there are a few points that need to be explained:

[0079] The drawings of the embodiments disclosed in this case only involve the structures involved in the embodiments disclosed in this case, and other structures can refer to the usual designs;

[0080] In the absence of conflict, the embodiments and features of the embodiments disclosed in this case can be combined with each other to obtain new embodiments;

[0081] The above are only specific implementation methods disclosed in this case, but the protection scope of the present disclosure is not limited thereto. The protection scope disclosed in this case should be based on the protection scope of the claims.

Claims

1. A method for measuring thermal conductivity and thermal resistance of a material, characterized in that: The following steps are involved: Step S100, placing the semiconductor device (1) in a high and low temperature chamber, measuring the relationship curve coefficient K1 between the cross voltage VF and the temperature T of the semiconductor device (1) under the condition of the detection current I1, that is, K1=(VFx-VFy) / (Tx-Ty), VFx and VFy are the cross voltages of the semiconductor device (1) under the conditions of the temperatures Tx and Ty respectively; Step S200, using a thermal resistance tester to measure the thermal resistance RTHJC from the internal chip PN junction to the bottom PAD of the semiconductor device (1); Step S300, placing the material to be tested (2) between the PADs of a pair of semiconductor devices (1); Step S400, detecting a cross voltage VF1 of the semiconductor device (1) under a detection current I1 at 25°C; According to Tjx=25℃+(VFx-VF1)*K1, the voltage across the semiconductor device (1) is obtained. X The corresponding junction temperature is Tjx; Step S500, applying a heating power P to the semiconductor device (1) below; Detecting a cross voltage VF2 of the lower semiconductor device (1) under a detection current I1; Detecting a voltage VF3 across the upper semiconductor device (1) under a detection current I1; Step S600, substitute the cross voltage VF2 and the cross voltage VF3 with the cross voltage VF1 into Tjx=25°C+(VFx-VF1)*K1 respectively, and obtain the junction temperature Tj1 of the lower semiconductor device (1) and the junction temperature Tj2 of the upper semiconductor device (1), Tj1=25°C+(VF2-VF1)*K1, Tj2=25°C+(VF3-VF1)*K1; Step S700, calculating the thermal resistance RTHJ1J2 from the internal chip PN junction of the lower semiconductor device (1) to the internal chip PN junction of the upper semiconductor device (1) = (Tj1-Tj2) / P; Step S800, calculating the thermal resistance RTH=RTHJ1J2-2RTHJC of the material to be tested, and the thermal conductivity λ=L / (RTH*S) of the material to be tested.

2. A method for measuring thermal conductivity and thermal resistance of a material according to claim 1, characterized in that: Step S100 includes: Step S110, placing the semiconductor device (1) in a high and low temperature chamber, and connecting the semiconductor device (1) and a semiconductor device electrical parameter tester (3) using a test lead to form a loop; Step S120, setting the detection current I1, testing the cross voltage VF at intervals of n°C within the range of 25-175°C, and obtaining the relationship curve coefficient K1 between the cross voltage VF and the temperature T.

3. A method for measuring thermal conductivity and thermal resistance of a material according to claim 1, characterized in that: Step S300 includes: Step S310, with the bottom PAD of the first semiconductor device (1) facing upwards, the material to be tested (2) is placed on the bottom PAD of the first semiconductor device (1), ensuring that the lower surface of the material to be tested (2) is horizontal and in close contact with the bottom PAD; Step S320, placing the second upper semiconductor device (1) with its bottom PAD facing downwards, over the material to be tested (2), ensuring that the upper surface of the material to be tested (2) is level and in close contact with the bottom PAD of the device.

4. A method for measuring thermal conductivity and thermal resistance of a material according to claim 1, characterized in that: Step S400 includes: Step S410, using a test wire to connect the semiconductor device (1) and the semiconductor device electrical parameter tester (3) to form a loop, setting the detection current to I1, and obtaining the cross-voltage VF1 of the semiconductor device (1) under the detection current I1 at 25°C.

5. A method for measuring thermal conductivity and thermal resistance of a material according to claim 1, characterized in that: Step S500 includes: Step S510, using a test wire to connect a pair of semiconductor devices (1) and a semiconductor device electrical parameter tester (3) to form a loop, and setting a detection current I1; Step S520, using a test wire to connect the lower semiconductor device (1) and the constant current source generator (4) to form a loop, and setting a heating power P; Step S530, applying a heating power P to the lower semiconductor device (1) until a thermal steady state is reached; Step S540, turning on the semiconductor device electrical parameter tester (3), detecting the cross voltage VF2 of the lower semiconductor device (1) under the condition of the detection current I1; and detecting the cross voltage VF3 of the upper semiconductor device (1) under the condition of the detection current I1.

6. A method for measuring thermal conductivity and thermal resistance of a material according to claim 1, characterized in that: The semiconductor device (1) is packaged in a manner that there is a PAD metal on the bottom.

7. A method for measuring thermal conductivity and thermal resistance of a material according to claim 1, characterized in that: The upper and lower surfaces of the material to be tested (2) are level, ensuring close contact with the bottom PADs of the two semiconductor devices (1).

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