Packaging structure of bismuth telluride thermoelectric device and preparation method thereof

Abstract

This invention belongs to the field of thermoelectric materials technology, specifically relating to a packaging structure and fabrication method of a bismuth telluride thermoelectric device. It includes a bismuth telluride substrate and a barrier layer deposited on the substrate. The barrier layer comprises an Fe-Ni-Cr barrier layer and a Ti-Au barrier layer. The Fe-Ni-Cr barrier layer is located on the upper surface of the bismuth telluride substrate, and a copper substrate is disposed on the upper surface of the Fe-Ni-Cr barrier layer. The Ti-Au barrier layer is located on the lower surface of the bismuth telluride substrate, and a silver electrode layer is disposed on the lower surface of the Ti-Au barrier layer. This invention deposits a barrier layer along the bismuth telluride substrate. The Fe-Ni-Cr layer constructs a stronger connection interface, providing stronger mechanical bonding performance in hindering subsequent element diffusion. The constructed Ti-Au barrier layer effectively improves the mechanical strength of the connection and diffusion blocking effect, showing significant advantages compared to a system without a barrier layer.

Description

Technical Field

[0001] This invention belongs to the field of thermoelectric materials technology, specifically relating to a packaging structure and preparation method of a bismuth telluride thermoelectric device. Background Technology

[0002] Thermoelectric materials are key materials for the direct conversion of heat energy into electrical energy. Thermoelectric devices are typically constructed by bonding a copper-clad ceramic substrate to a p-type or n-type thermoelectric material with a barrier layer using solder. The barrier layer design aims to suppress the diffusion of interfacial elements during soldering or use, preventing performance degradation or failure of the device. In the performance evaluation of thermoelectric devices, reliability, stability, and efficiency all place high demands on the performance of the heterogeneous interface.

[0003] Bismuth telluride-based thermoelectric materials have attracted much attention due to their potential applications in high-efficiency energy conversion and cooling technologies. However, the widely used metallic Ni, Fe, and Ni-based alloys as barrier layers (e.g., application number 201510143511.3, a bismuth telluride-based thermoelectric power generation element and its preparation method, wherein the barrier layer material is metallic nickel or a nickel-copper binary alloy) all have some performance limitations in practical applications, such as poor barrier effect on element diffusion, poor bonding, high resistivity, and insufficient stability at high temperatures. These factors limit the further application of bismuth telluride-based materials. Summary of the Invention

[0004] To address the aforementioned issues, this invention provides a packaging structure and fabrication method for a bismuth telluride thermoelectric device. The aim is to provide a bismuth telluride thermoelectric device with strong barrier properties, strong bonding, low resistivity, and good weldability. The device involves depositing a Fe-Ni-Cr barrier layer and a Ti-Au barrier layer along a bismuth telluride substrate. The Fe-Ni-Cr layer constructs a stronger connection interface, providing enhanced mechanical bonding performance in hindering subsequent element diffusion. The constructed Ti-Au barrier layer effectively improves the mechanical strength of the connection and diffusion blocking effect, exhibiting significant advantages compared to systems without barrier layers.

[0005] The present invention solves the above-mentioned technical problems through the following technical solutions.

[0006] The first objective of this invention is to provide a packaging structure for a bismuth telluride thermoelectric device, comprising a bismuth telluride substrate and a barrier layer deposited on the bismuth telluride substrate. The barrier layer comprises an Fe-Ni-Cr barrier layer and a Ti-Au barrier layer. The Fe-Ni-Cr barrier layer is located on the upper surface of the bismuth telluride substrate, and a copper substrate is disposed on the upper surface of the Fe-Ni-Cr barrier layer. The Ti-Au barrier layer is located on the lower surface of the bismuth telluride substrate, and a silver electrode layer is disposed on the lower surface of the Ti-Au barrier layer.

[0007] Furthermore, in the packaging structure of the above-mentioned bismuth telluride thermoelectric device, the thickness of the Fe-Ni-Cr barrier layer is 240nm to 300nm.

[0008] Furthermore, in the packaging structure of the above-mentioned bismuth telluride thermoelectric device, the thickness of the Ti-Au barrier layer is 200nm to 240nm.

[0009] Furthermore, in the packaging structure of the aforementioned bismuth telluride thermoelectric device, the bismuth telluride substrate is formed from a p-type or n-type bismuth telluride bulk material.

[0010] A second objective of this invention is to provide a method for fabricating the packaging structure of the aforementioned bismuth telluride thermoelectric device, comprising the following steps:

[0011] Using a magnetron sputtering process, Fe, Ni, and Cr layers are sequentially deposited on the upper surface of a bismuth telluride substrate to obtain an Fe-Ni-Cr barrier layer, and Ti and Au layers are sequentially deposited on the lower surface of the bismuth telluride substrate to obtain a Ti-Au barrier layer.

[0012] A copper substrate and Fe-Ni-Cr barrier layer were welded together, and a silver electrode layer was welded together with a Ti-Au barrier layer to obtain the packaging structure of the bismuth telluride thermoelectric device.

[0013] Furthermore, during the magnetron sputtering deposition of the Fe-Ni-Cr barrier layer, the sputtering power of the Fe target was 100W–150W, and the sputtering time was 2400s–3000s; the sputtering power of the Ni target was 50W–200W, and the sputtering time was 2400s–3000s; and the sputtering power of the Cr target was 50W–200W, and the sputtering time was 2400s–3000s.

[0014] Furthermore, during the magnetron sputtering deposition of the Ti-Au barrier layer, the sputtering power of the Ti target is 100–130 W, and the sputtering time is 1200–1800 s; the sputtering power of the Au target is 80 W–120 W, and the sputtering time is 1200–1800 s.

[0015] Furthermore, magnetron sputtering is performed in a vacuum inert gas atmosphere, using Ne or Ar gas, with a flow rate of 20 ccm–30 sccm, a pressure of 0.3 Pa–0.5 Pa, and a vacuum level of 1.0 × 10⁻⁶. -4 ~6.0×10 -4 Pa.

[0016] Furthermore, the thicknesses of the Fe, Ni, and Cr layers are all 80 nm to 100 nm; the thicknesses of the Ti and Au layers are all 100 nm to 120 nm.

[0017] Furthermore, the brazing connection process conditions are as follows: the temperature is raised to 160℃~200℃ in an atmospheric environment, and held at 160℃~200℃ for 1min~10min, and then cooled to room temperature at a cooling rate of 1℃ / min~10℃ / min to complete the brazing connection between the bismuth telluride thermoelectric material and the electrode or the bismuth telluride thermoelectric material and the copper substrate.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] This invention proposes a packaging structure for bismuth telluride thermoelectric devices. Fe-Ni-Cr and Ti-Au barrier layers are deposited along a bismuth telluride substrate. The constructed Fe-Ni-Cr layer creates a stronger connection interface, providing enhanced mechanical bonding performance while hindering subsequent element diffusion. The lower barrier height after introducing the Fe-Ni-Cr layer is the main reason for the reduced contact resistance. Furthermore, Cr, as an adhesive material, can make the connection tighter and promote better electrical contact. The constructed Ti-Au barrier layer has a stable multi-layer interface structure, which can suppress element diffusion, maintain a low specific contact resistivity, and achieve good critical load. These characteristics are achieved because a Ti-Au barrier layer of appropriate thickness can maintain the stability of the multi-layer interface, keeping the interface as an effective junction, reducing stress release, and effectively improving the mechanical strength and diffusion blocking effect of the connection, showing significant advantages compared to systems without barrier layers. Simultaneously, both the Fe-Ni-Cr and Ti-Au barrier layers have strong anti-interface diffusion capabilities. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of the packaging structure of the bismuth telluride thermoelectric device of the present invention. Attached image description:

[0022] 1. Bismuth telluride substrate, 2. Fe-Ni-Cr barrier layer, 3. Ti-Au barrier layer, 4. Copper substrate, 5. Silver electrode layer. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] It should be noted that the technical terms used in this invention are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of this invention. Certain terms are used in this invention to refer to specific components. Those skilled in the art will understand that different terms may be used to refer to the same component. This invention does not distinguish components based on differences in terminology, but rather on differences in function. As used throughout the specification and claims, "comprising" and "including" are open-ended terms and should be understood as "comprising but not limited to".

[0025] Application No. 201510143511.3 discloses a bismuth telluride-based thermoelectric power generation element and its preparation method, wherein the barrier layer material is metallic nickel or a nickel-copper binary alloy. However, in practical applications, these materials exhibit some performance limitations, including poor barrier effect against element diffusion, poor bonding, high resistivity, and insufficient stability at high temperatures. These factors restrict the further application of bismuth telluride-based materials.

[0026] To address the aforementioned problems, on the one hand, this invention provides a packaging structure for a bismuth telluride thermoelectric device, such as... Figure 1 As shown, the substrate includes a bismuth telluride substrate 1 and a barrier layer deposited on the bismuth telluride substrate 1. The barrier layer includes an Fe-Ni-Cr barrier layer 2 and a Ti-Au barrier layer 3. The Fe-Ni-Cr barrier layer 2 is located on the upper surface of the bismuth telluride substrate 1. A copper substrate 4 is disposed on the upper surface of the Fe-Ni-Cr barrier layer 2. The Ti-Au barrier layer 3 is located on the lower surface of the bismuth telluride substrate 1. A silver electrode layer 5 is disposed on the lower surface of the Ti-Au barrier layer 3.

[0027] This invention proposes a packaging structure for a bismuth telluride thermoelectric device. An Fe-Ni-Cr barrier layer 2 and a Ti-Au barrier layer 3 are deposited along a bismuth telluride substrate. The Fe-Ni-Cr layer 2 constructs a stronger connection interface, providing stronger mechanical bonding performance in hindering subsequent element diffusion. The lower barrier height after introducing the Fe-Ni-Cr layer 3 is the main reason for the reduced contact resistance. Furthermore, Cr, as an adhesive material, can make the connection tighter and promote better electrical contact. The constructed Ti-Au barrier layer 3 has a stable multi-layer interface structure, which can suppress element diffusion, maintain a low specific contact resistivity, and achieve good critical load. These characteristics are achieved because the appropriately thick Ti-Au barrier layer 3 can maintain the stability of the multi-layer interface, keep the interface as an effective junction, reduce stress release, and effectively improve the mechanical strength of the connection and diffusion blocking effect, showing significant advantages compared to a system without a barrier layer. Simultaneously, both the Fe-Ni-Cr barrier layer 2 and the Ti-Au barrier layer 3 have strong anti-interface diffusion capabilities.

[0028] In some specific embodiments, an Fe-Ni-Cr barrier layer 2 is deposited on the upper surface of the bismuth telluride substrate 1, the thickness of which is 160 nm to 200 nm. Compared with a single Ni layer (which results in poor Ni-Te layer formation and Bi diffusion problems) and a Ni-Cr layer (which is easy to peel off), the Fe-Ni-Cr barrier layer 2 can create a stronger connection interface and provide stronger mechanical bonding performance in hindering the diffusion of subsequent elements.

[0029] In some specific embodiments, a Ti-Au barrier layer 3 is deposited on the lower surface of the bismuth telluride substrate 1, and the thickness of the Ti-Au barrier layer 3 is 200 nm to 240 nm. Constructing a Ti-Au barrier layer 3 between the bismuth telluride substrate 1 and the silver electrode layer 5 can effectively improve the mechanical strength of the connection and the diffusion barrier effect, which has significant advantages compared with Pd, Ni-Au and systems without a barrier layer.

[0030] In some specific embodiments, the bismuth telluride thermoelectric device packaging structure described above, wherein the bismuth telluride substrate is formed from p-type or n-type bismuth telluride bulk material.

[0031] On the other hand, the present invention provides a method for preparing the packaging structure of the above-mentioned bismuth telluride thermoelectric device, comprising the following steps:

[0032] Using a magnetron sputtering process, Fe, Ni and Cr layers are sequentially deposited on the upper surface of the bismuth telluride substrate 1 to obtain Fe-Ni-Cr barrier layer 2, and Ti and Au layers are sequentially deposited on the lower surface of the bismuth telluride substrate 1 to obtain Ti-Au barrier layer 3.

[0033] The copper substrate 4 and the Fe-Ni-Cr barrier layer 2 are welded together, the silver electrode layer 5 is welded to the Ti-Au barrier layer 2, and the bismuth telluride substrate and the Fe-Ni-Cr barrier layer 3 are welded together.

[0034] In some specific embodiments, during the deposition of the Fe-Ni-Cr barrier layer 2 by magnetron sputtering, the sputtering power of the Fe target is 100W to 150W and the sputtering time is 2400s to 3000s; the sputtering power of the Ni target is 50W to 200W and the sputtering time is 2400s to 3000s; and the sputtering power of the Cr target is 50W to 200W and the sputtering time is 2400s to 3000s.

[0035] In some specific embodiments, during the deposition of the Ti-Au barrier layer 3 by magnetron sputtering, the sputtering power of the Ti target is 100-130W and the sputtering time is 1200s-1800s; the sputtering power of the Au target is 80W-120W and the sputtering time is 1200s-1800s.

[0036] Specifically, Fe-Ni-Cr barrier layer 2 and Ti-Au barrier layer 3 are deposited on the upper and lower surfaces of the bismuth telluride substrate 1 using magnetron sputtering. This results in a denser microstructure, stronger interfacial bonding, and better uniformity of the Fe-Ni-Cr barrier layer 2 and Ti-Au barrier layer 3. The Fe-Ni-Cr layer creates a stronger connection interface, providing stronger mechanical bonding performance in hindering the diffusion of subsequent elements. The Ti / Au barrier layer effectively improves the mechanical strength of the connection and the diffusion barrier effect, showing significant advantages compared to the system without a barrier layer.

[0037] In some specific embodiments, the thicknesses of the Fe, Ni, and Cr layers are all 80 nm to 100 nm; the thicknesses of the Ti and Au layers are all 100 nm to 120 nm.

[0038] It should be noted that the Cr content in Fe-Ni-Cr barrier layer 2 can be optimized according to the corrosion environment of the material; the thickness of the Ti layer in Ti-Au barrier layer 2 can be appropriately reduced to lower costs.

[0039] In some specific embodiments, the welding process involves assembling a brazing filler metal sheet between the copper substrate 4 and the Fe-Ni-Cr barrier layer 2, or between the Ti-Au barrier layer 3 and the silver electrode layer 5, and then cooling it in the furnace to complete the brazing connection between the bismuth telluride thermoelectric material and the electrode or between the bismuth telluride thermoelectric material and the copper substrate. The brazing filler metal sheet is SnIn, SnBi, or SnBiAg. The brazing connection process conditions are as follows: heating to 160℃~200℃ in an atmospheric environment, holding at 160℃~200℃ for 1min~10min, and then cooling to room temperature at a cooling rate of 1℃ / min~10℃ / min to complete the brazing connection between the bismuth telluride thermoelectric material and the electrode or between the bismuth telluride thermoelectric material and the copper substrate.

[0040] The following specific examples will provide further explanation.

[0041] Example 1

[0042] A packaging structure for a bismuth telluride thermoelectric device, such as Figure 1As shown, the substrate includes a bismuth telluride substrate 1 and a barrier layer deposited on the bismuth telluride substrate 1. The barrier layer includes an Fe-Ni-Cr barrier layer 2 and a Ti-Au barrier layer 3. The Fe-Ni-Cr barrier layer 2 has a thickness of 300 nm, and the Ti-Au barrier layer 3 has a thickness of 210 nm. The Fe-Ni-Cr barrier layer 2 is located on the upper surface of the bismuth telluride substrate 1. A copper substrate 4 is disposed on the upper surface of the Fe-Ni-Cr barrier layer 2. The Ti-Au barrier layer 3 is located on the lower surface of the bismuth telluride substrate 1. A silver electrode layer 5 is disposed on the lower surface of the Ti-Au barrier layer 3. The bismuth telluride substrate is formed from a p-type bismuth telluride bulk material.

[0043] The method for fabricating the packaging structure of the above-mentioned bismuth telluride thermoelectric device includes the following steps:

[0044] S1. Using magnetron sputtering, the bismuth telluride substrate 1 is placed in a magnetron sputtering apparatus, and the Fe target material is installed on the target position. The purity of the Fe target material is 99.99%. Subsequently, a vacuum system consisting of a mechanical pump and a molecular pump is used to evacuate the coating chamber to a vacuum level of 6.0 × 10⁻⁶. -4 High-purity Ar gas was introduced into the cavity at a flow rate of 20 sccm and a pressure of 0.3 Pa. The DC power supply connected to the Fe target was turned on, with a power setting of 150 W and a sputtering time of 2500 s, resulting in an Fe layer with a thickness of 100 nm. Then, the Ni target with a purity of 99.99% was used, with a power setting of 100 W and a sputtering time of 2500 s, resulting in a Ni layer with a thickness of 100 nm. Finally, the Cr target with a purity of 99.99% was used, with a power setting of 100 W and a sputtering time of 2500 s, resulting in a Cr layer with a thickness of 100 nm, thus obtaining the Fe-Ni-Cr barrier layer 2.

[0045] S2. Using magnetron sputtering, a bismuth telluride substrate 1 with a deposited Fe-Ni-Cr barrier layer 2 is placed in a magnetron sputtering apparatus. A Ti-Au barrier layer is deposited on the other side of the bismuth telluride substrate 1, i.e., the side without the Fe-Ni-Cr barrier layer 2. A Ti target with a purity of 99.99% is mounted on the target site. Subsequently, a vacuum system consisting of a mechanical pump and a molecular pump is used to evacuate the coating chamber to a vacuum level of 6.0 × 10⁻⁶. -4 High-purity Ar gas was introduced into the cavity at a flow rate of 20 sccm and a pressure of 0.3 Pa. The DC power supply connected to the Ti target was turned on, with a power setting of 120 W and a sputtering time of 1500 s, resulting in a Ti layer with a thickness of 110 nm. Then, the Au target with a purity of 99.99% was used, with a power setting of 100 W and a sputtering time of 1500 s, resulting in an Au layer with a thickness of 110 nm.

[0046] S3. Using a welding process, SnIn solder is placed on the surfaces to be welded between the Fe-Ni-Cr barrier layer 2 and the copper substrate 4, and brazing is performed. The temperature is raised to 200℃ under atmospheric conditions and held at 200℃ for 5 minutes, then cooled to room temperature at a rate of 2℃ / min. At this point, the copper substrate 4 and the Fe-Ni-Cr barrier layer 2 are welded. Subsequently, SnIn solder is placed on the surfaces to be welded between the Ti-Au barrier layer 3 and the silver electrode layer 5, and brazing is performed. The temperature is raised to 200℃ under atmospheric conditions and held at 200℃ for 5 minutes, then cooled to room temperature at a rate of 2℃ / min. At this point, the Ti-Au barrier layer 3 and the silver electrode layer 5 are welded. The resulting packaging structure of the bismuth telluride thermoelectric device is obtained.

[0047] Example 2

[0048] A packaging structure for a bismuth telluride thermoelectric device, such as Figure 1 As shown, the substrate includes a bismuth telluride substrate 1 and a barrier layer deposited on the bismuth telluride substrate 1. The barrier layer includes an Fe-Ni-Cr barrier layer 2 and a Ti-Au barrier layer 3. The Fe-Ni-Cr barrier layer 2 has a thickness of 300 nm, and the Ti-Au barrier layer 3 has a thickness of 210 nm. The Fe-Ni-Cr barrier layer 2 is located on the upper surface of the bismuth telluride substrate 1. A copper substrate 4 is disposed on the upper surface of the Fe-Ni-Cr barrier layer 2. The Ti-Au barrier layer 3 is located on the lower surface of the bismuth telluride substrate 1. A silver electrode layer 5 is disposed on the lower surface of the Ti-Au barrier layer 3. The bismuth telluride substrate is formed from an n-type bismuth telluride bulk material.

[0049] The method for fabricating the packaging structure of the above-mentioned bismuth telluride thermoelectric device includes the following steps:

[0050] S1. Using magnetron sputtering, the bismuth telluride substrate 1 is placed in a magnetron sputtering apparatus, and the Fe target material is installed on the target position. The purity of the Fe target material is 99.99%. Subsequently, a vacuum system consisting of a mechanical pump and a molecular pump is used to evacuate the coating chamber to a vacuum level of 6.0 × 10⁻⁶. -4 High-purity Ar gas was introduced into the cavity at a flow rate of 20 sccm and a pressure of 0.3 Pa. The DC power supply connected to the Fe target was turned on, with a power setting of 150 W and a sputtering time of 2500 s, resulting in an Fe layer with a thickness of 100 nm. Then, the Ni target with a purity of 99.99% was used, with a power setting of 100 W and a sputtering time of 2500 s, resulting in a Ni layer with a thickness of 100 nm. Finally, the Cr target with a purity of 99.99% was used, with a power setting of 100 W and a sputtering time of 2500 s, resulting in a Cr layer with a thickness of 100 nm, thus obtaining the Fe-Ni-Cr barrier layer 2.

[0051] S2. Using magnetron sputtering, a bismuth telluride substrate 1 with a deposited Fe-Ni-Cr barrier layer 2 is placed in a magnetron sputtering apparatus. A Ti-Au barrier layer is deposited on the other side of the bismuth telluride substrate 1, i.e., the side without the Fe-Ni-Cr barrier layer 2. A Ti target with a purity of 99.99% is mounted on the target site. Subsequently, a vacuum system consisting of a mechanical pump and a molecular pump is used to evacuate the coating chamber to a vacuum level of 6.0 × 10⁻⁶. -4 High-purity Ar gas was introduced into the cavity at a flow rate of 20 sccm and a pressure of 0.3 Pa. The DC power supply connected to the Ti target was turned on, with a power setting of 120 W and a sputtering time of 1500 s, resulting in a Ti layer with a thickness of 110 nm. Then, the Au target with a purity of 99.99% was used, with a power setting of 100 W and a sputtering time of 1500 s, resulting in an Au layer with a thickness of 100 nm.

[0052] S3. Using a welding process, SnIn solder is placed on the surfaces to be welded between the Fe-Ni-Cr barrier layer 2 and the copper substrate 4, and brazing is performed. The temperature is raised to 200℃ under atmospheric conditions and held at 200℃ for 5 minutes, then cooled to room temperature at a rate of 2℃ / min. At this point, the copper substrate 4 and the Fe-Ni-Cr barrier layer 2 are welded. Subsequently, SnIn solder is placed on the surfaces to be welded between the Ti-Au barrier layer 3 and the silver electrode layer 5, and brazing is performed. The temperature is raised to 200℃ under atmospheric conditions and held at 200℃ for 5 minutes, then cooled to room temperature at a rate of 2℃ / min. At this point, the Ti-Au barrier layer 3 and the silver electrode layer 5 are welded. The resulting packaging structure of the bismuth telluride thermoelectric device is obtained.

[0053] The bismuth telluride thermoelectric device encapsulation structure specimens obtained in Examples 1 and 2, measuring 2.5 mm × 2.5 mm, were placed in a quartz tube, and a quartz column was inserted. The tube was evacuated and heated with a high-temperature flame until it was sealed. The sealed quartz tube was placed in a muffle furnace, heated to 250°C for one hour, and maintained at 250°C for annealing for 45 days. Afterward, it was cooled with the furnace to assess its thermal stability, and its contact resistance was tested using the four-probe method. The measured contact resistance between the p-type bismuth telluride and the barrier layer was 2.2 × 10⁻⁶. -6 Ω / cm 2 The contact resistance between n-type bismuth telluride and the barrier layer is 1.91 × 10⁻⁶. -6 Ω / cm 2 The contact resistance between p-type bismuth telluride and the barrier layer after annealing is 2.37 × 10⁻⁶. -6 Ω / cm 2 The contact resistance between n-type bismuth telluride and the barrier layer is 2.01 × 10⁻⁶. -6 Ω / cm2 There was no significant decrease, indicating good thermal stability.

[0054] Example 3

[0055] A packaging structure for a bismuth telluride thermoelectric device, such as Figure 1 As shown, the substrate includes a bismuth telluride substrate 1 and a barrier layer deposited on the bismuth telluride substrate 1. The barrier layer includes an Fe-Ni-Cr barrier layer 2 and a Ti-Au barrier layer 3. The Fe-Ni-Cr barrier layer 2 has a thickness of 240 nm, and the Ti-Au barrier layer 3 has a thickness of 200 nm. The Fe-Ni-Cr barrier layer 2 is located on the upper surface of the bismuth telluride substrate 1. A copper substrate 4 is disposed on the upper surface of the Fe-Ni-Cr barrier layer 2. The Ti-Au barrier layer 3 is located on the lower surface of the bismuth telluride substrate 1. A silver electrode layer 5 is disposed on the lower surface of the Ti-Au barrier layer 3. The bismuth telluride substrate is formed from a p-type bismuth telluride bulk material.

[0056] The method for fabricating the packaging structure of the above-mentioned bismuth telluride thermoelectric device includes the following steps:

[0057] S1. Using magnetron sputtering, the bismuth telluride substrate 1 is placed in a magnetron sputtering apparatus, and the Fe target material is installed on the target position. The purity of the Fe target material is 99.99%. Subsequently, a vacuum system consisting of a mechanical pump and a molecular pump is used to evacuate the coating chamber to a vacuum level of 5.0 × 10⁻⁶. -4 High-purity Ar gas was introduced into the cavity at a flow rate of 30 sccm and a pressure of 0.3 Pa. The DC power supply connected to the Fe target was turned on, with a power setting of 100 W and a sputtering time of 300 s, resulting in an Fe layer with a thickness of 80 nm. Then, the Ni target with a purity of 99.99% was used, with a power setting of 100 W and a sputtering time of 2500 s, resulting in a Ni layer with a thickness of 80 nm. Finally, the Cr target with a purity of 99.99% was used, with a power setting of 100 W and a sputtering time of 2500 s, resulting in a Cr layer with a thickness of 80 nm, thus obtaining the Fe-Ni-Cr barrier layer 2.

[0058] S2. Using magnetron sputtering, a bismuth telluride substrate 1 with a deposited Fe-Ni-Cr barrier layer 2 is placed in a magnetron sputtering apparatus. A Ti-Au barrier layer is deposited on the other side of the bismuth telluride substrate 1, i.e., the side without the Fe-Ni-Cr barrier layer 2. A Ti target with a purity of 99.99% is mounted on the target site. Subsequently, a vacuum system consisting of a mechanical pump and a molecular pump is used to evacuate the coating chamber to a vacuum level of 5.0 × 10⁻⁶. -4High-purity Ar gas was introduced into the cavity at a flow rate of 30 sccm and a pressure of 0.3 Pa. The DC power supply connected to the Ti target was turned on, with a power of 100 W and a sputtering time of 1500 s, resulting in a Ti layer with a thickness of 100 nm. Then, the Au target with a purity of 99.99% was used, with a power of 80 W and a sputtering time of 1800 s, resulting in an Au layer with a thickness of 100 nm.

[0059] S3. Using a welding process, SnIn solder is placed on the surfaces to be welded between the Fe-Ni-Cr barrier layer 2 and the copper substrate 4, and brazing is performed. The temperature is raised to 160℃ under atmospheric conditions and held at 160℃ for 10 minutes, then cooled to room temperature at a rate of 3℃ / min. At this point, the copper substrate 4 and the Fe-Ni-Cr barrier layer 2 are welded. Subsequently, SnIn solder is placed on the surfaces to be welded between the Ti-Au barrier layer 3 and the silver electrode layer 5, and brazing is performed. The temperature is raised to 160℃ under atmospheric conditions and held at 160℃ for 10 minutes, then cooled to room temperature at a rate of 3℃ / min. At this point, the Ti-Au barrier layer 3 and the silver electrode layer 5 are welded. The resulting packaging structure of the bismuth telluride thermoelectric device is obtained.

[0060] Example 4

[0061] A packaging structure for a bismuth telluride thermoelectric device, such as Figure 1 As shown, the substrate includes a bismuth telluride substrate 1 and a barrier layer deposited on the bismuth telluride substrate 1. The barrier layer includes an Fe-Ni-Cr barrier layer 2 and a Ti-Au barrier layer 3. The Fe-Ni-Cr barrier layer 2 has a thickness of 270 nm, and the Ti-Au barrier layer 3 has a thickness of 240 nm. The Fe-Ni-Cr barrier layer 2 is located on the upper surface of the bismuth telluride substrate 1. A copper substrate 4 is disposed on the upper surface of the Fe-Ni-Cr barrier layer 2. The Ti-Au barrier layer 3 is located on the lower surface of the bismuth telluride substrate 1. A silver electrode layer 5 is disposed on the lower surface of the Ti-Au barrier layer 3. The bismuth telluride substrate is formed from a p-type bismuth telluride bulk material.

[0062] The method for fabricating the packaging structure of the above-mentioned bismuth telluride thermoelectric device includes the following steps:

[0063] S1. Using magnetron sputtering, the bismuth telluride substrate 1 is placed in a magnetron sputtering apparatus, and the Fe target material is installed on the target position. The purity of the Fe target material is 99.99%. Subsequently, a vacuum system consisting of a mechanical pump and a molecular pump is used to evacuate the coating chamber to a vacuum level of 1.0 × 10⁻⁶. -4High-purity Ar gas was introduced into the cavity at a flow rate of 25 sccm and a pressure of 0.4 Pa. The DC power supply connected to the Fe target was turned on, with a power setting of 120 W and a sputtering time of 2400 s, resulting in an Fe layer with a thickness of 100 nm. Then, the Ni target was replaced with one with a purity of 99.99%, a power setting of 200 W, and a sputtering time of 2400 s, resulting in a Ni layer with a thickness of 90 nm. Finally, the Cr target was replaced with one with a purity of 99.99%, a power setting of 200 W, and a sputtering time of 2500 s, resulting in a Cr layer with a thickness of 90 nm, thus obtaining the Fe-Ni-Cr barrier layer 2.

[0064] S2. Using magnetron sputtering, a bismuth telluride substrate 1 with a deposited Fe-Ni-Cr barrier layer 2 is placed in a magnetron sputtering apparatus. A Ti-Au barrier layer is deposited on the other side of the bismuth telluride substrate 1, i.e., the side without the Fe-Ni-Cr barrier layer 2. A Ti target with a purity of 99.99% is mounted on the target site. Subsequently, a vacuum system consisting of a mechanical pump and a molecular pump is used to evacuate the coating chamber to a vacuum level of 1.0 × 10⁻⁶. -4 High-purity Ar gas was introduced into the cavity at a flow rate of 30 sccm and a pressure of 0.4 Pa. The DC power supply connected to the Ti target was turned on, with a power of 130 W and a sputtering time of 1200 s, resulting in a Ti layer with a thickness of 110 nm. Then, the Au target with a purity of 99.99% was used, with a power of 120 W and a sputtering time of 1800 s, resulting in an Au layer with a thickness of 130 nm.

[0065] S3. Using a welding process, SnIn solder is placed on the surfaces to be soldered between the Fe-Ni-Cr barrier layer 2 and the copper substrate 4, and brazing is performed. The temperature is raised to 180°C under atmospheric conditions and held at 180°C for 1 minute, then cooled to room temperature at a rate of 1°C / min. At this point, the copper substrate 4 and the Fe-Ni-Cr barrier layer 2 are welded. Subsequently, SnIn solder is placed on the surfaces to be soldered between the Ti-Au barrier layer 3 and the silver electrode layer 5, and brazing is performed. The temperature is raised to 180°C under atmospheric conditions and held at 180°C for 1 minute, then cooled to room temperature at a rate of 1°C / min. At this point, the Ti-Au barrier layer 3 and the silver electrode layer 5 are welded. The resulting bismuth telluride thermoelectric device packaging structure is obtained.

[0066] Tests showed that the contact resistance between p-type bismuth telluride and the barrier layer in Examples 3 and 4 was basically the same as that in Example 1. After annealing, the contact resistance between p-type bismuth telluride and the barrier layer did not decrease significantly, indicating good thermal stability.

[0067] It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described here to avoid redundancy. Although preferred embodiments of the invention have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this invention.

[0068] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A packaging structure for a bismuth telluride thermoelectric device, characterized in that, The substrate includes a bismuth telluride substrate (1) and a barrier layer deposited on the bismuth telluride substrate (1). The barrier layer includes a Fe-Ni-Cr barrier layer (2) and a Ti-Au barrier layer (3). The Fe-Ni-Cr barrier layer (2) is located on the upper surface of the bismuth telluride substrate (1). A copper substrate (4) is disposed on the upper surface of the Fe-Ni-Cr barrier layer (2). The Ti-Au barrier layer (3) is located on the lower surface of the bismuth telluride substrate (1). A silver electrode layer (5) is disposed on the lower surface of the Ti-Au barrier layer (3). The Fe-Ni-Cr barrier layer (2) is a Fe layer, a Ni layer and a Cr layer deposited sequentially on the upper surface of the bismuth telluride substrate (1). The Ti-Au barrier layer (3) is a Ti layer and an Au layer deposited sequentially on the lower surface of the bismuth telluride substrate (1).

2. The packaging structure of the bismuth telluride thermoelectric device according to claim 1, characterized in that, The thickness of the Fe-Ni-Cr barrier layer (2) is 240 nm to 300 nm.

3. The packaging structure of the bismuth telluride thermoelectric device according to claim 1, characterized in that, The thickness of the Ti-Au barrier layer (3) is 200nm to 240nm.

4. The packaging structure of the bismuth telluride thermoelectric device according to claim 1, characterized in that, The bismuth telluride substrate is formed from p-type or n-type bismuth telluride bulk material.

5. A method for preparing the packaging structure of the bismuth telluride thermoelectric device according to any one of claims 1-4, characterized in that, Includes the following steps: Using a magnetron sputtering process, Fe, Ni and Cr layers are sequentially deposited on the upper surface of a bismuth telluride substrate (1) to obtain an Fe-Ni-Cr barrier layer (2), and Ti and Au layers are sequentially deposited on the lower surface of the bismuth telluride substrate (1) to obtain a Ti-Au barrier layer (3). The copper substrate (4) and the Fe-Ni-Cr barrier layer (2) are welded together by welding, and the silver electrode layer (5) is welded together with the Ti-Au barrier layer (3); thus obtaining the packaging structure of the bismuth telluride thermoelectric device.

6. The method for preparing the packaging structure of the bismuth telluride thermoelectric device according to claim 5, characterized in that, During the deposition of Fe-Ni-Cr barrier layer by magnetron sputtering (2), the sputtering power of Fe target is 100W to 150W and the sputtering time is 2400s to 3000s; the sputtering power of Ni target is 50W to 200W and the sputtering time is 2400s to 3000s; the sputtering power of Cr target is 50W to 200W and the sputtering time is 2400s to 3000s.

7. The method for preparing the packaging structure of the bismuth telluride thermoelectric device according to claim 5, characterized in that, During the deposition of Ti-Au barrier layer by magnetron sputtering (3), the sputtering power of Ti target is 100-130W and the sputtering time is 1200s-1800s; the sputtering power of Au target is 80W-120W and the sputtering time is 1200s-1800s.

8. The method for preparing the packaging structure of the bismuth telluride thermoelectric device according to claim 5, characterized in that, Magnetron sputtering was performed in a vacuum inert gas atmosphere, using Ne or Ar gas at a flow rate of 20 ccm–30 sccm, a pressure of 0.3 Pa–0.5 Pa, and a vacuum level of 1.0 × 10⁻⁶. -4 ~6.0×10 -4 Pa.

9. The method for preparing the packaging structure of the bismuth telluride thermoelectric device according to claim 5, characterized in that, The thicknesses of the Fe, Ni, and Cr layers are all 80 nm to 100 nm; the thicknesses of the Ti and Au layers are all 100 nm to 120 nm.

10. The method for preparing the packaging structure of the bismuth telluride thermoelectric device according to claim 5, characterized in that, The brazing connection process conditions are as follows: the temperature is raised to 160℃~200℃ under atmospheric conditions, and held at 160℃~200℃ for 1min~10min. Then, the temperature is lowered to room temperature at a cooling rate of 1℃ / min~10℃ / min to complete the brazing connection between the bismuth telluride thermoelectric material and the electrode or the bismuth telluride thermoelectric material and the copper substrate.

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