Method for enhancing high temperature stability of thermoelectric semiconductor devices

Abstract

The present invention relates to a method for enhancing the high-temperature stability of a thermoelectric semiconductor device. The thermoelectric semiconductor device comprises: two copper substrates, and a plurality of thermoelectric arms whose ends are interconnected by welding to the two copper substrates in a one-to-one correspondence. The thermoelectric arms are made of antimony telluride, and both ends of the thermoelectric arms have nickel plates that facilitate welding. Sn paste is printed on the copper substrates using a printing screen, and the amount of Sn paste between the copper substrates and the thermoelectric arms is controlled. The thermoelectric arms and the copper substrates are assembled to form a thermoelectric semiconductor assembly. The thermoelectric semiconductor assembly is heated in a vacuum state with low welding pressure to achieve welding interconnection. No Sn bridges are generated between the thermoelectric arms of the manufactured thermoelectric semiconductor device. When the device operates in a high-temperature environment for a long time, element diffusion is unlikely to occur at the welding interface, and Cu elements in the copper substrates will not diffuse into the thermoelectric arms, thereby enhancing high-temperature stability.

Description

Technical Field

[0001] The present invention relates to the technical field of thermoelectric semiconductor devices, in particular to a method for enhancing the high-temperature stability of thermoelectric semiconductor devices. Background Art

[0002] Semiconductors can generate a much greater thermoelectric potential than metals, resulting in highly efficient conversion of heat and electricity. Thermoelectric power generation often utilizes thermoelectric semiconductor devices for thermoelectric conversion. These devices consist of two copper substrates and multiple thermoelectric arms made of thermoelectric material. The ends of the thermoelectric arms are soldered to the two copper substrates in a one-to-one correspondence. The invention, filed in Chinese Patent Application No. CN202010419067.4, relates to a high-reliability thermoelectric module system comprising N individual thermoelectric modules. Each module comprises a semiconductor thermoelectric arm, a copper conductive sheet, and an insulating layer. A single thermoelectric module is a thermoelectric semiconductor device, a copper conductive sheet is a copper substrate, and a semiconductor thermoelectric arm is a thermoelectric arm. The thermoelectric arms and copper conductive sheets are often welded using a hot (carbon) plate welding heating method and interconnected by Sn welding. Since the copper substrate is subjected to a large welding pressure during welding, element diffusion is prone to occur at the welding interface. During welding, the excess Sn will be squeezed out, and Sn bridges are prone to form between the thermoelectric arms. When working in a high-temperature environment for a long time, the Cu element of the copper substrate will diffuse into the thermoelectric arms through the diffusion channel Sn bridge, causing the composition of the thermoelectric arms to change, affecting the resistance and thermoelectric performance of the thermoelectric semiconductor device, reducing the stability of the thermoelectric semiconductor device in a high-temperature environment, and shortening its service life. Therefore, a method for enhancing the high-temperature stability of thermoelectric semiconductor devices is designed in which element diffusion is not prone to occur at the welding interface, Sn bridges are not formed between the thermoelectric arms, Cu element of the copper substrate will not diffuse into the thermoelectric arms when working in a high-temperature environment for a long time, and the resistance and thermoelectric performance of the thermoelectric semiconductor device will not be affected, thereby enhancing the stability of the thermoelectric semiconductor device in a high-temperature environment. This has become an urgent problem to be solved. Summary of the Invention

[0003] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a method for enhancing the high-temperature stability of thermoelectric semiconductor devices, in which element diffusion is not easily generated at the welding interface and Sn bridges are not easily generated between thermoelectric arms. When working in a high-temperature environment for a long time, the Cu element of the copper substrate will not diffuse into the thermoelectric arms, and will not affect the resistance and thermoelectric performance of the thermoelectric semiconductor device, thereby enhancing the stability of the thermoelectric semiconductor device in a high-temperature environment.

[0004] The specific technical solution of the present invention is:

[0005] A method for enhancing the high-temperature stability of a thermoelectric semiconductor device. The thermoelectric semiconductor device comprises: two copper substrates; a plurality of thermoelectric arms whose ends are interconnected by welding to the two copper substrates in a one-to-one correspondence; the thermoelectric arms are made of antimony telluride; and both ends of the thermoelectric arms have nickel plates that facilitate welding. Sn paste is printed on the copper substrates using a printing screen; the amount of Sn paste between the copper substrates and the thermoelectric arms is controlled; the thermoelectric arms and the copper substrates are assembled to form a thermoelectric semiconductor assembly; the thermoelectric semiconductor assembly is heated in a vacuum state with low welding pressure to achieve welding interconnection. No Sn bridges are formed between the thermoelectric arms of the manufactured thermoelectric semiconductor device; and when operated in a high-temperature environment for a long time, element diffusion is less likely to occur at the welding interface; the Cu element of the copper substrates does not diffuse into the thermoelectric arms, thereby enhancing high-temperature stability.

[0006] Preferably, the method for enhancing the high-temperature stability of a thermoelectric semiconductor device comprises the following steps: step 1, preparing a thermoelectric arm, a copper substrate, and Sn paste; step 2, designing and manufacturing a printing stencil; step 3, printing the Sn paste onto the copper substrate through the printing stencil; step 4, assembling the thermoelectric arm and the copper substrate to form a thermoelectric semiconductor assembly; step 5, placing the thermoelectric semiconductor assembly in a vacuum welding furnace for welding and interconnection, and then cooling after high-temperature insulation to form a thermoelectric semiconductor device.

[0007] Preferably, in the step 2, the mesh holes of the printing screen pass through both ends of the printing screen, the cross-sectional shape of the mesh holes is designed according to the shape and size of the welding surface of the thermoelectric arm, the cross-sectional shape of the mesh holes is a similar shape corresponding to the welding surface of the thermoelectric arm, and the size of the mesh holes is 0.8 to 1.2 times the size of the welding surface of the thermoelectric arm; adjacent mesh holes cannot be interconnected; the shape of the mesh holes is square, rectangular or circular.

[0008] Preferably, the cross-sectional shape of the mesh is a square that is the same as the welding surface of the thermoelectric arm; the welding surface size of the thermoelectric arm is 1.32mm*1.32mm, and the height size of the thermoelectric arm is *1.5mm.

[0009] Preferably, in the step three, the Sn paste is printed on the copper substrate, and the end of the Sn paste away from the copper substrate is flush with the end of the mesh away from the copper substrate.

[0010] Preferably, in the step five, when the thermoelectric semiconductor components are placed in a vacuum welding furnace for welding interconnection, the preheating heating rate is ≤4°C / s, the welding temperature is 250°C to 310°C, the welding time is 10 to 40s, the vacuum degree is maintained at ≤10Pa during welding, the holding temperature is 190 to 210°C, the time is 90 to 120s, and the cooling rate is ≤4°C / s.

[0011] Preferably, the vacuum soldering furnace is a vacuum reflow soldering furnace.

[0012] Compared with the prior art, the present invention has the following beneficial effects: the method for enhancing the high-temperature stability of thermoelectric semiconductor devices comprises designing a corresponding printing screen according to the shape and size of the welding surface of the thermoelectric arm, printing Sn paste on the copper substrate through the printing screen, controlling the amount of Sn paste between the copper substrate and the thermoelectric arm, and heating under a vacuum state with low welding pressure to achieve welding interconnection. Sn bridges are not generated between the thermoelectric arms, the diffusion path of Cu from the copper substrate to the thermoelectric arm is reduced, and Cu diffusion is inhibited. When operating in a high-temperature environment for a long time, Cu elements from the copper substrate will not diffuse into the thermoelectric arm, which will not affect the resistance and thermoelectric performance of the thermoelectric semiconductor device, thereby enhancing the stability of the thermoelectric semiconductor device in a high-temperature environment. The vacuum welding furnace is used for heating and welding, which facilitates the control of the pressure during the welding process and prevents the Sn paste from being squeezed out in large quantities due to high welding pressure during the welding process, thereby forming Sn bridges. The vacuum welding furnace is a vacuum reflow oven, which uses the principle of infrared radiation heating and has the characteristics of uniform temperature, ultra-low temperature safe welding, no temperature difference, no overheating, reliable and stable process parameters, no need for complex process testing, and low environmental cost operation. When thermoelectric semiconductor components are placed in a vacuum welding furnace for welding and interconnection, the preheating heating rate is ≤4℃ / s, the welding temperature is 250℃ to 310℃, the welding time is 10 to 40s, the vacuum degree is maintained at ≤10Pa during welding, the holding temperature is 190 to 210℃, the time is 90 to 120s, and the cooling rate is ≤4℃ / s, which is conducive to ensuring the welding and interconnection quality of thermoelectric semiconductor devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Schematic diagram of the structure of the thermoelectric semiconductor device of the present invention;

[0014] Figure 2 This is a schematic diagram of the structure of the original thermoelectric semiconductor device with Sn bridge;

[0015] Figure 3 This is a comparison of the resistance change rate of thermoelectric semiconductor devices with and without Sn bridges.

[0016] In the figure: copper substrate 1, thermoelectric arm 2, Sn paste 3, Sn bridge 4, resistance change rate curve A without Sn bridge, resistance change rate curve B with Sn bridge. DETAILED DESCRIPTION

[0017] The present invention will be further described below with reference to the accompanying drawings.

[0018] As attached Figure 1 , Attachment Figure 2The invention discloses a method for enhancing the high-temperature stability of a thermoelectric semiconductor device. The thermoelectric semiconductor device comprises: two copper substrates 1; and a plurality of thermoelectric arms 2 whose ends are interconnected by copper soldering to the two copper substrates 1 in a one-to-one correspondence. Sn paste 3 is printed on the copper substrates 1 using a printing screen, and the amount of Sn paste 3 between the copper substrates 1 and the thermoelectric arms 2 is controlled. The thermoelectric arms 2 and the copper substrates 1 are assembled to form a thermoelectric semiconductor assembly. The thermoelectric semiconductor assembly is heated in a vacuum state with low soldering pressure to achieve soldering interconnection. No Sn bridge 4 is generated between the thermoelectric arms 2 of the manufactured thermoelectric semiconductor device. When the device operates in a high-temperature environment for a long time, element diffusion is not easily generated at the soldering interface, and the Cu element of the copper substrates 1 does not diffuse into the thermoelectric arms 2, thereby enhancing the high-temperature stability.

[0019] The method for enhancing the high-temperature stability of a thermoelectric semiconductor device comprises the following steps: step 1, preparing a thermoelectric arm 2, a copper substrate 1, and a Sn paste 3; step 2, designing and manufacturing a printing stencil; step 3, printing the Sn paste 3 onto the copper substrate 1 using the printing stencil; step 4, assembling the thermoelectric arm 2 and the copper substrate 1 to form a thermoelectric semiconductor assembly; and step 5, placing the thermoelectric semiconductor assembly in a vacuum soldering furnace for soldering and interconnection, and then cooling after high-temperature insulation to form a thermoelectric semiconductor device.

[0020] In the step 2, the mesh of the printing screen passes through both ends of the printing screen, and the cross-sectional shape of the mesh is designed according to the shape and size of the welding surface of the thermoelectric arm 2. The cross-sectional shape of the mesh is similar to the shape corresponding to the welding surface of the thermoelectric arm 2, and the size of the mesh is 0.8 to 1.2 times the size of the welding surface of the thermoelectric arm 2; adjacent meshes cannot be interconnected; the shape of the mesh is square, rectangular or circular.

[0021] In this embodiment, the cross-sectional shape of the mesh is a square that is the same as the welding surface of the thermoelectric arm 2; the welding surface size of the thermoelectric arm 2 is 1.32mm*1.32mm, the height size of the thermoelectric arm 2 is *1.5mm; the mesh size is 1.32mm*1.32mm.

[0022] In the step three, the Sn paste 3 is printed on the copper substrate 1, and the end of the Sn paste 3 away from the copper substrate 1 is flush with the end of the mesh away from the copper substrate 1; the Sn paste 3 is a SnSb-based Sn paste 3.

[0023] In step 5, when the thermoelectric semiconductor components are placed in a vacuum soldering furnace for interconnection soldering, the preheating rate is ≤4°C / s, the soldering temperature is 250°C to 310°C, the soldering time is 10 to 40 seconds, the vacuum is maintained at ≤10 Pa, the holding temperature is 190 to 210°C for 90 to 120 seconds, and the cooling rate is ≤4°C / s. In this embodiment, the soldering temperature is 290°C, the soldering time is 30 seconds, the vacuum is maintained at 5 Pa, the holding temperature is 175°C for 100 seconds, and the resistance change rate is 23.36% after cooling for 32 hours, which is lower than the 42.86% resistance change rate of the thermoelectric semiconductor device with Sn bridge after cooling for the same 32 hours.

[0024] The vacuum soldering furnace is a vacuum reflow soldering furnace.

[0025] In addition to the above-mentioned embodiments, within the scope disclosed in the claims and description of the present invention, the technical features or technical data of the present invention can be reselected and combined to form new embodiments. These can be achieved by those skilled in the art without creative work. Therefore, these embodiments that are not described in detail in the present invention should also be regarded as specific embodiments of the present invention and within the scope of protection of the present invention.

Claims

1. A method for enhancing the high-temperature stability of a thermoelectric semiconductor device, the thermoelectric semiconductor device comprising: Two copper substrates, and multiple thermoelectric arms whose ends are welded and interconnected with the copper of the two copper substrates in a one-to-one correspondence. The invention is characterized in that Sn paste is printed on the copper substrates using a printing screen, the cross-sectional shape of the mesh of the printing screen is similar to the shape corresponding to the welding surface of the thermoelectric arm, and the size is 0.8 to 1.2 times the size of the welding surface of the thermoelectric arm, and adjacent meshes cannot be interconnected; the amount of Sn paste between the copper substrate and the thermoelectric arm is controlled so that the end of the Sn paste away from the copper substrate is flush with the end of the mesh away from the copper substrate, the thermoelectric arm and the copper substrate are assembled to form a thermoelectric semiconductor component, and the thermoelectric semiconductor component is heated in a vacuum state to achieve welding and interconnection. No Sn bridge is generated between the thermoelectric arms of the manufactured thermoelectric semiconductor device. When working in a high-temperature environment for a long time, element diffusion is not easily generated at the welding interface, and the Cu element of the copper substrate will not diffuse into the thermoelectric arm, thereby enhancing high-temperature stability.

2. The method for enhancing the high-temperature stability of a thermoelectric semiconductor device according to claim 1, characterized in that it comprises the following steps: step 1, preparing a thermoelectric arm, a copper substrate, and Sn paste; step 2, designing and manufacturing a printing screen; step 3, printing the Sn paste onto the copper substrate using the printing screen; step 4, assembling the thermoelectric arm and the copper substrate to form a thermoelectric semiconductor assembly; step 5, placing the thermoelectric semiconductor assembly in a vacuum soldering furnace for soldering and interconnection, and then cooling after high-temperature insulation to form a thermoelectric semiconductor device.

3. The method for enhancing the high temperature stability of a thermoelectric semiconductor device according to claim 2, wherein: In the step 2, the mesh holes of the printing screen pass through both ends of the printing screen, and the cross-sectional shape of the mesh holes is designed according to the shape and size of the welding surface of the thermoelectric arm. The cross-sectional shape of the mesh holes is a similar shape corresponding to the welding surface of the thermoelectric arm, and the size of the mesh holes is 0.8 to 1.2 times the size of the welding surface of the thermoelectric arm; adjacent mesh holes cannot be interconnected.

4. The method for enhancing the high temperature stability of a thermoelectric semiconductor device according to claim 3, wherein: The cross-sectional shape of the mesh is a square which is the same as the welding surface of the thermoelectric arm.

5. The method for enhancing the high temperature stability of a thermoelectric semiconductor device according to claim 3, wherein: In the step three, the Sn paste is printed on the copper substrate, and the end of the Sn paste away from the copper substrate is flush with the end of the mesh away from the copper substrate.

6. The method for enhancing the high temperature stability of a thermoelectric semiconductor device according to claim 2, 3, 4 or 5, characterized in that: In the step 5, when the thermoelectric semiconductor assembly is placed in a vacuum welding furnace for welding interconnection, the preheating heating rate is ≤4°C / s, the welding temperature is 250°C to 310°C, the welding time is 10 to 40s, the vacuum degree is maintained at ≤10Pa during welding, the holding temperature is 190 to 210°C, the time is 90 to 120s, and the cooling rate is ≤4°C / s.

7. The method for enhancing the high temperature stability of a thermoelectric semiconductor device according to claim 6, wherein: The vacuum soldering furnace is a vacuum reflow soldering furnace.

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