Packaging structure of bismuth telluride thermoelectric device and preparation method thereof

Abstract

The invention belongs to the technical field of thermoelectric materials, and particularly relates to a packaging structure of a bismuth telluride thermoelectric device and a preparation method of the packaging structure. Comprising a bismuth telluride substrate and barrier layers deposited on the bismuth telluride substrate, the barrier layers comprise a 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, a copper substrate is arranged 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 arranged on the lower surface of the Ti-Au barrier layer. The barrier layer is deposited on the bismuth telluride substrate, the Fe-Ni-Cr layer constructs a stronger connection interface, and stronger mechanical connection performance is provided in the process of hindering subsequent element diffusion; the constructed Ti-Au barrier layer effectively improves the mechanical strength and diffusion barrier effect of connection, and has remarkable advantages compared with a system without a barrier layer.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermoelectric materials, and in particular relates to a packaging structure of a bismuth telluride thermoelectric device and a preparation method thereof. Background Art

[0002] As a key material for the direct conversion of heat and electricity, the devices of thermoelectric materials are usually made by soldering copper-clad ceramic substrates and p-type and n-type thermoelectric materials containing barrier layers. The barrier layer is designed to inhibit the diffusion of interface elements during welding or use, and prevent the attenuation or failure of device performance. In the performance evaluation of thermoelectric devices, their reliability, stability and efficiency all place high demands on the performance of heterogeneous interfaces.

[0003] Bismuth telluride-based thermoelectric materials have attracted much attention due to their potential applications in efficient energy conversion and cooling technologies. However, the currently widely used metal Ni, Fe and Ni-based alloys as barrier layers, such as application number 201510143511.3, a bismuth telluride-based thermoelectric power generation element and its preparation method, the barrier layer material is metal nickel or nickel-copper binary alloy; in practical applications, there are some performance limitations, such as poor blocking effect on element diffusion, poor bonding and high resistivity, and insufficient stability in high temperature environments. These factors limit the further application of bismuth telluride-based materials. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a packaging structure of a bismuth telluride thermoelectric device and a preparation method thereof, aiming to provide a bismuth telluride thermoelectric device with strong barrier properties, strong bonding properties, low resistivity and good weldability, wherein a Fe-Ni-Cr barrier layer and a Ti-Au barrier layer are deposited along a bismuth telluride substrate, wherein the Fe-Ni-Cr layer constructs a stronger connection interface, providing stronger mechanical connection performance in the process of hindering subsequent element diffusion; the constructed Ti-Au barrier layer effectively improves the mechanical strength and diffusion barrier effect of the connection, and has significant advantages over a system without a barrier layer.

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

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

[0007] Furthermore, in the packaging structure of the 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 bismuth telluride thermoelectric device, the thickness of the Ti—Au barrier layer is 200 nm to 240 nm.

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

[0010] A second object of the present invention is to provide a method for preparing the packaging structure of the above-mentioned bismuth telluride thermoelectric device, comprising the following steps:

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

[0012] The copper substrate and the Fe-Ni-Cr barrier layer are welded, and the silver electrode layer and the Ti-Au barrier layer are welded by welding to obtain the packaging structure of the bismuth telluride thermoelectric device.

[0013] Furthermore, in the process of depositing the Fe-Ni-Cr barrier layer by magnetron sputtering, the sputtering power of the Fe target is 100W~150W, and the sputtering time is 2400s~3000s; the sputtering power of the Ni target is 50W~200W, and the sputtering time is 2400s~3000s; the sputtering power of the Cr target is 50W~200W, and the sputtering time is 2400s~3000s.

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

[0015] Furthermore, magnetron sputtering is carried out in a vacuum inert gas atmosphere, wherein the inert gas is Ne gas or Ar gas, the inert gas flow rate is 20 ccm to 30 sccm, the gas pressure is 0.3 Pa to 0.5 Pa, and the vacuum degree is 1.0×10 -4 ~6.0×10 -4 Pa.

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

[0017] Furthermore, the brazing connection process conditions are as follows: heating to 160°C to 200°C in an atmospheric environment, and keeping the temperature at 160°C to 200°C for 1min to 10min, and then cooling to room temperature at a cooling rate of 1°C / min to 10°C / 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 beneficial effects:

[0019] The present invention proposes a packaging structure of a bismuth telluride thermoelectric device, wherein a Fe-Ni-Cr barrier layer and a Ti-Au barrier layer are deposited along a bismuth telluride substrate, and the constructed Fe-Ni-Cr layer constructs a stronger connection interface, providing stronger mechanical connection performance in the process of hindering subsequent element diffusion. The lower barrier height after the introduction of the Fe-Ni-Cr layer is the main reason for reducing the contact resistance. In addition, 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, can inhibit element diffusion, maintain a low specific contact resistivity, and obtain a good critical load. These characteristics are achieved because the Ti-Au barrier layer with a suitable thickness can maintain the stability of the multi-layer interface, keep the interface as an effective junction, and reduce stress release, effectively improve the mechanical strength and diffusion barrier effect of the connection, and have significant advantages over the system without a barrier layer. At the same time, both the Fe-Ni-Cr barrier layer and the Ti-Au barrier layer have a strong ability to prevent interface diffusion. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the overall structure of the packaging structure of the bismuth telluride thermoelectric device of the present invention. Description of the drawings:

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

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] It should be noted that the professional terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Certain words are used in the present invention to refer to specific components. Those skilled in the art should understand that technicians will use different nouns to refer to the same component. The present invention does not distinguish between components by the difference in nouns, but by the difference in the functions of the components. As mentioned in the entire specification and claims, "including" and "comprising" are open terms and should be understood as "including but not limited to".

[0025] Application No. 201510143511.3, a bismuth telluride-based thermoelectric power generation element and its preparation method, the barrier layer material is metal nickel or nickel-copper binary alloy; in practical applications, there are some performance limitations, including poor barrier effect on element diffusion, poor bonding and high resistivity, and insufficient stability in high temperature environments. These factors limit the further application of bismuth telluride-based materials.

[0026] Based on the above problems, on the one hand, the present invention provides a packaging structure of a bismuth telluride thermoelectric device, such as Figure 1 As shown, it 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, the upper surface of the Fe-Ni-Cr barrier layer 2 is provided with a copper substrate 4, the Ti-Au barrier layer 3 is located on the lower surface of the bismuth telluride substrate 1, and the lower surface of the Ti-Au barrier layer 3 is provided with a silver electrode layer 5.

[0027] The present invention proposes a packaging structure of a bismuth telluride thermoelectric device, wherein a Fe-Ni-Cr barrier layer 2 and a Ti-Au barrier layer 3 are deposited along a bismuth telluride substrate, wherein the Fe-Ni-Cr layer 2 constructs a stronger connection interface, provides stronger mechanical connection performance in the process of hindering subsequent element diffusion, and the lower barrier height after the introduction of the Fe-Ni-Cr layer 3 is the main reason for reducing the contact resistance. In addition, 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, can inhibit element diffusion, maintain a low specific contact resistivity, and obtain a good critical load. These characteristics are achieved because the Ti-Au barrier layer 3 with a suitable thickness can maintain the stability of the multi-layer interface, maintain the interface as an effective junction, and reduce stress release, effectively improve the mechanical strength and diffusion barrier effect of the connection, and have significant advantages over the system without a barrier layer. At the same time, both the Fe-Ni-Cr barrier layer 2 and the Ti-Au barrier layer 3 have a strong ability to prevent interface diffusion.

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

[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 200nm to 240nm. The construction of the Ti-Au barrier layer 3 between the bismuth telluride substrate 1 and the silver electrode layer 5 can effectively improve the mechanical strength and diffusion barrier effect of the connection, which has significant advantages over Pd, Ni-Au and systems without a barrier layer.

[0030] In some specific embodiments, in the packaging structure of the bismuth telluride thermoelectric device, the bismuth telluride substrate is formed of a p-type or n-type bismuth telluride-based bulk material.

[0031] In another aspect, the present invention provides a method for preparing the packaging structure of the bismuth telluride thermoelectric device, comprising the following steps:

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

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

[0034] In some specific embodiments, during the process of depositing the Fe-Ni-Cr barrier layer 2 by magnetron sputtering, the sputtering power of the Fe target is 100W~150W, and the sputtering time is 2400s~3000s; the sputtering power of the Ni target is 50W~200W, and the sputtering time is 2400s~3000s; the sputtering power of the Cr target is 50W~200W, and the sputtering time is 2400s~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 100-130 W, and the sputtering time is 1200 s-1800 s; the sputtering power of the Au target is 80 W-120 W, and the sputtering time is 1200 s-1800 s.

[0036] Among them, a Fe-Ni-Cr barrier layer 2 and a Ti-Au barrier layer 3 are deposited on the upper surface and the lower surface of the bismuth telluride substrate 1 by means of a magnetron sputtering process, so that the Fe-Ni-Cr barrier layer 2 and the Ti-Au barrier layer 3 have denser structures, stronger interface bonding strength, and better uniformity. The Fe-Ni-Cr layer constructs a stronger connection interface, providing stronger mechanical connection performance in the process of hindering the subsequent diffusion of elements; the Ti / Au barrier layer is constructed to effectively improve the mechanical strength and diffusion barrier effect of the connection, which has significant advantages over the system without a barrier layer.

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

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

[0039] In some specific embodiments, the welding process is to assemble by placing a solder sheet on the surface to be welded between the copper substrate 4 and the Fe-Ni-Cr barrier layer 2 or the surface to be welded between the Ti-Au barrier layer 3 and the silver electrode layer 5, perform brazing, and then cool with the furnace to complete the brazing connection between the bismuth telluride thermoelectric material and the electrode or the bismuth telluride thermoelectric material and the copper substrate; wherein the solder sheet is SnIn solder, SnBi solder or SnBiAg solder; the brazing connection process conditions are: heating to 160°C to 200°C in an atmospheric environment, and keeping at 160°C to 200°C for 1min to 10min, and then cooling to room temperature at a cooling rate of 1°C / min to 10°C / 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.

[0040] The invention is further described below through specific examples.

[0041] Example 1

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

[0043] The method for preparing the packaging structure of the bismuth telluride thermoelectric device comprises the following steps:

[0044] S1. By adopting the magnetron sputtering process, the bismuth telluride substrate 1 is placed in the magnetron sputtering equipment, and the Fe target material is installed on the target position. The purity of the Fe target material is 99.99%. Then, the vacuum system composed of a mechanical pump and a molecular pump is used to evacuate the coating chamber to a vacuum degree of 6.0×10 -4 Pa, high-purity Ar gas is introduced into the cavity, the gas flow rate is 20sccm, the gas pressure is 0.3Pa, the DC power supply connected to the Fe target is turned on, the power is set to 150W, the sputtering time is 2500s, and an Fe layer is obtained with a thickness of 100nm; then the Ni target is replaced, the purity of the Ni target is 99.99%, the power is set to 100W, the sputtering time is 2500s, and a Ni layer is obtained with a thickness of 100nm; finally, the Cr target is replaced, the purity of the Cr target is 99.99%, the power is set to 100W, the sputtering time is 2500s, and a Cr layer is obtained with a thickness of 100nm, namely, a Fe-Ni-Cr barrier layer 2 is obtained.

[0045] S2. By adopting the magnetron sputtering process, the bismuth telluride substrate 1 deposited with the Fe-Ni-Cr barrier layer 2 is placed in the magnetron sputtering equipment, and a Ti-Au barrier layer is deposited on the other side of the bismuth telluride substrate 1, that is, the side without the Fe-Ni-Cr barrier layer 2, and a Ti target is installed on the target position. The purity of the Ti target is 99.99%. Then, a vacuum system composed of a mechanical pump and a molecular pump is used to evacuate the coating chamber to a vacuum degree of 6.0×10 -4 Pa, high-purity Ar gas is introduced into the cavity, the gas flow rate is 20sccm, the gas pressure is 0.3Pa, the DC power supply connected to the Ti target is turned on, the power is set to 120W, the sputtering time is 1500s, and a Ti layer is obtained with a thickness of 110nm. Then the Au target is replaced with a Au target with a purity of 99.99%. The power is set to 100W, the sputtering time is 1500s, and an Au layer is obtained with a thickness of 110nm.

[0046] S3. Using a welding process, place SnIn solder on the surfaces to be welded of the Fe-Ni-Cr barrier layer 2 and the copper substrate 4 for brazing, heat it to 200°C in an atmospheric environment, keep it at 200°C for 5 minutes, then cool it down to room temperature at a rate of 2°C / min. At this time, the copper substrate 4 and the Fe-Ni-Cr barrier layer 2 are welded; then, place the SnIn solder on the surfaces to be welded of the Ti-Au barrier layer 3 and the silver electrode layer 5 for brazing, heat it to 200°C in an atmospheric environment, keep it at 200°C for 5 minutes, then cool it down to room temperature at a rate of 2°C / min. At this time, the Ti-Au barrier layer 3 and the silver electrode layer 5 are welded; and obtain the packaging structure of the bismuth telluride thermoelectric device.

[0047] Example 2

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

[0049] The method for preparing the packaging structure of the bismuth telluride thermoelectric device comprises the following steps:

[0050] S1. By adopting the magnetron sputtering process, the bismuth telluride substrate 1 is placed in the magnetron sputtering equipment, and the Fe target material is installed on the target position. The purity of the Fe target material is 99.99%. Then, the vacuum system composed of a mechanical pump and a molecular pump is used to evacuate the coating chamber to a vacuum degree of 6.0×10 -4 Pa, high-purity Ar gas is introduced into the cavity, the gas flow rate is 20sccm, the gas pressure is 0.3Pa, the DC power supply connected to the Fe target is turned on, the power is set to 150W, the sputtering time is 2500s, and an Fe layer is obtained with a thickness of 100nm; then the Ni target is replaced, the purity of the Ni target is 99.99%, the power is set to 100W, the sputtering time is 2500s, and a Ni layer is obtained with a thickness of 100nm; finally, the Cr target is replaced, the purity of the Cr target is 99.99%, the power is set to 100W, the sputtering time is 2500s, and a Cr layer is obtained with a thickness of 100nm, namely, a Fe-Ni-Cr barrier layer 2 is obtained.

[0051] S2. By adopting the magnetron sputtering process, the bismuth telluride substrate 1 deposited with the Fe-Ni-Cr barrier layer 2 is placed in the magnetron sputtering equipment, and a Ti-Au barrier layer is deposited on the other side of the bismuth telluride substrate 1, that is, the side without the Fe-Ni-Cr barrier layer 2, and a Ti target is installed on the target position. The purity of the Ti target is 99.99%. Then, a vacuum system composed of a mechanical pump and a molecular pump is used to evacuate the coating chamber to a vacuum degree of 6.0×10 -4 Pa, high-purity Ar gas is introduced into the cavity, the gas flow rate is 20sccm, the gas pressure is 0.3Pa, the DC power supply connected to the Ti target is turned on, the power is set to 120W, the sputtering time is 1500s, and a Ti layer is obtained with a thickness of 110nm. Then the Au target is replaced with a Au target with a purity of 99.99%. The power is set to 100W, the sputtering time is 1500s, and an Au layer is obtained with a thickness of 100nm.

[0052] S3. Using a welding process, place SnIn solder on the surfaces to be welded of the Fe-Ni-Cr barrier layer 2 and the copper substrate 4 for brazing, heat it to 200°C in an atmospheric environment, keep it at 200°C for 5 minutes, then cool it down to room temperature at a rate of 2°C / min. At this time, the copper substrate 4 and the Fe-Ni-Cr barrier layer 2 are welded; then, place the SnIn solder on the surfaces to be welded of the Ti-Au barrier layer 3 and the silver electrode layer 5 for brazing, heat it to 200°C in an atmospheric environment, keep it at 200°C for 5 minutes, then cool it down to room temperature at a rate of 2°C / min. At this time, the Ti-Au barrier layer 3 and the silver electrode layer 5 are welded; and obtain the packaging structure of the bismuth telluride thermoelectric device.

[0053] The packaging structure specimens of the bismuth telluride thermoelectric device obtained in Example 1 and Example 2 were 2.5 mm × 2.5 mm in size, placed in a quartz tube, inserted into a quartz column, evacuated to a vacuum, and heated with a high-temperature flame aimed at the quartz column until the quartz tube was sealed. The sealed quartz tube was placed in a muffle furnace, heated to 250°C in one hour and maintained at 250°C for annealing for 45 days, and then cooled with the furnace to assess thermal stability, and the contact resistance was tested using the four-probe method. The test showed that the contact resistance between the p-type bismuth telluride and the barrier layer was 2.2×10 -6 Ω / cm 2 The contact resistance between n-type bismuth telluride and the barrier layer is 1.91×10 -6 Ω / cm 2 ; After annealing, the contact resistance between p-type bismuth telluride and the barrier layer is 2.37×10 -6 Ω / cm 2 The contact resistance between n-type bismuth telluride and the barrier layer is 2.01×10 -6 Ω / cm2 , there is no obvious decline, and the thermal stability is good.

[0054] Example 3

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

[0056] The method for preparing the packaging structure of the bismuth telluride thermoelectric device comprises the following steps:

[0057] S1. By adopting the magnetron sputtering process, the bismuth telluride substrate 1 is placed in the magnetron sputtering equipment, and the Fe target material is installed on the target position. The purity of the Fe target material is 99.99%. Then, the vacuum system composed of a mechanical pump and a molecular pump is used to evacuate the coating chamber to a vacuum degree of 5.0×10 -4 Pa, high-purity Ar gas is introduced into the cavity, the gas flow rate is 30sccm, the gas pressure is 0.3Pa, the DC power supply connected to the Fe target is turned on, the power is set to 100W, the sputtering time is 300s, and an Fe layer is obtained with a thickness of 80nm; then the Ni target is replaced, the purity of the Ni target is 99.99%, the power is set to 100W, the sputtering time is 2500s, and a Ni layer is obtained with a thickness of 80nm; finally, the Cr target is replaced, the purity of the Cr target is 99.99%, the power is set to 100W, the sputtering time is 2500s, and a Cr layer is obtained with a thickness of 80nm, namely, a Fe-Ni-Cr barrier layer 2 is obtained.

[0058] S2. By adopting the magnetron sputtering process, the bismuth telluride substrate 1 deposited with the Fe-Ni-Cr barrier layer 2 is placed in the magnetron sputtering equipment, and a Ti-Au barrier layer is deposited on the other side of the bismuth telluride substrate 1, that is, the side without the Fe-Ni-Cr barrier layer 2, and a Ti target is installed on the target position. The purity of the Ti target is 99.99%. Then, a vacuum system composed of a mechanical pump and a molecular pump is used to evacuate the coating chamber to a vacuum degree of 5.0×10 -4Pa, high-purity Ar gas is introduced into the chamber, the gas flow rate is 30sccm, the gas pressure is 0.3Pa, the DC power supply connected to the Ti target is turned on, the power is set to 100W, the sputtering time is 1500s, and a Ti layer is obtained with a thickness of 100nm. Then it is replaced with an Au target with a purity of 99.99%. The power is set to 80W, the sputtering time is 1800s, and an Au layer is obtained with a thickness of 100nm.

[0059] S3. Using a welding process, place the SnIn solder on the surfaces to be welded of the Fe-Ni-Cr barrier layer 2 and the copper substrate 4 for brazing. Heat the temperature to 160°C in an atmospheric environment, keep it at 160°C for 10 minutes, and then cool it down to room temperature at a rate of 3°C / min. At this time, the copper substrate 4 and the Fe-Ni-Cr barrier layer 2 are welded. Subsequently, place the SnIn solder on the surfaces to be welded of the Ti-Au barrier layer 3 and the silver electrode layer 5 for brazing. Heat the temperature to 160°C in an atmospheric environment, keep it at 160°C for 10 minutes, and then cool it down to room temperature at a rate of 3°C / min. At this time, the Ti-Au barrier layer 3 and the silver electrode layer 5 are welded. The packaging structure of the bismuth telluride thermoelectric device is obtained.

[0060] Example 4

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

[0062] The method for preparing the packaging structure of the bismuth telluride thermoelectric device comprises the following steps:

[0063] S1. By adopting the magnetron sputtering process, the bismuth telluride substrate 1 is placed in the magnetron sputtering equipment, and the Fe target material is installed on the target position. The purity of the Fe target material is 99.99%. Then, the vacuum system composed of a mechanical pump and a molecular pump is used to evacuate the coating chamber to a vacuum degree of 1.0×10 -4Pa, high-purity Ar gas is introduced into the cavity, the gas flow rate is 25sccm, the gas pressure is 0.4Pa, the DC power supply connected to the Fe target is turned on, the power is set to 120W, the sputtering time is 2400s, and an Fe layer is obtained with a thickness of 100nm; then the Ni target is replaced, the purity of the Ni target is 99.99%, the power is set to 200W, the sputtering time is 2400s, and a Ni layer is obtained with a thickness of 90nm; finally, the Cr target is replaced, the purity of the Cr target is 99.99%, the power is set to 200W, the sputtering time is 2500s, and a Cr layer is obtained with a thickness of 90nm, namely, a Fe-Ni-Cr barrier layer 2 is obtained.

[0064] S2. By adopting the magnetron sputtering process, the bismuth telluride substrate 1 deposited with the Fe-Ni-Cr barrier layer 2 is placed in the magnetron sputtering equipment, and a Ti-Au barrier layer is deposited on the other side of the bismuth telluride substrate 1, that is, the side without the Fe-Ni-Cr barrier layer 2, and a Ti target is installed on the target position. The purity of the Ti target is 99.99%. Then, a vacuum system composed of a mechanical pump and a molecular pump is used to evacuate the coating chamber to a vacuum degree of 1.0×10 -4 Pa, high-purity Ar gas is introduced into the chamber with a gas flow rate of 30 sccm and a gas pressure of 0.4 Pa. The DC power supply connected to the Ti target is turned on, the power is set to 130 W, the sputtering time is 1200 s, and a Ti layer is obtained with a thickness of 110 nm. The Au target is then replaced with a Au target with a purity of 99.99%. The power is set to 120 W, the sputtering time is 1800 s, and an Au layer is obtained with a thickness of 130 nm.

[0065] S3. Using a welding process, place the SnIn solder on the surfaces to be welded of the Fe-Ni-Cr barrier layer 2 and the copper substrate 4 for brazing. Heat the temperature to 180°C in an atmospheric environment, keep it at 180°C for 1 minute, and then cool it down to room temperature at a rate of 1°C / min. At this time, the copper substrate 4 and the Fe-Ni-Cr barrier layer 2 are welded. Subsequently, place the SnIn solder on the surfaces to be welded of the Ti-Au barrier layer 3 and the silver electrode layer 5 for brazing. Heat the temperature to 180°C in an atmospheric environment, keep it at 180°C for 1 minute, and then cool it down to room temperature at a rate of 1°C / min. At this time, the Ti-Au barrier layer 3 and the silver electrode layer 5 are welded. The packaging structure of the bismuth telluride thermoelectric device is obtained.

[0066] The test shows that the contact resistance between the p-type bismuth telluride and the barrier layer in Examples 3 and 4 is basically the same as that in Example 1. After annealing, the contact resistance between the p-type bismuth telluride and the barrier layer is basically the same as that in Example 1, with no obvious decrease, and good thermal stability.

[0067] It should be noted that when the present invention involves a numerical range, it should be understood that the two 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 those in the embodiments, in order to avoid redundancy, the present invention describes a preferred embodiment. Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the attached claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0068] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

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

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 240nm-300nm.

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-240nm.

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

5. A method for preparing a packaging structure of a bismuth telluride thermoelectric device according to any one of claims 1 to 4, characterized in that: The following steps are involved: By means of a magnetron sputtering process, an Fe layer, a Ni layer and a Cr layer are sequentially deposited on the upper surface of a bismuth telluride substrate (1) to obtain a Fe-Ni-Cr barrier layer (2), and a Ti layer and an Au layer are sequentially deposited on the lower surface of the bismuth telluride substrate (1) to obtain a Ti-Au barrier layer (3); A copper substrate (4) and a Fe-Ni-Cr barrier layer (2) are welded, and a silver electrode layer (5) and a Ti-Au barrier layer (3) are welded by welding, thereby obtaining a packaging structure of a 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: In the process of depositing the Fe-Ni-Cr barrier layer (2) by magnetron sputtering, the sputtering power of the Fe target is 100W-150W, and the sputtering time is 2400s-3000s; the sputtering power of the Ni target is 50W-200W, and the sputtering time is 2400s-3000s; the sputtering power of the Cr target is 50W-200W, and the sputtering time is 2400s-3000s.

7. The method for preparing the packaging structure of the bismuth telluride thermoelectric device according to claim 5, characterized in that: In the process of depositing 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.

8. The method for preparing the packaging structure of the bismuth telluride thermoelectric device according to claim 5, characterized in that: Magnetron sputtering is carried out in a vacuum inert gas atmosphere. The inert gas is Ne gas or Ar gas. The inert gas flow rate is 20ccm to 30sccm, the gas pressure is 0.3Pa to 0.5Pa, and the vacuum degree is 1.0×10 -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 thickness of the Fe layer, the Ni layer and the Cr layer are all 80nm-100nm; the thickness of the Ti layer and the Au layer are all 100nm-120nm.

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: heating to 160°C to 200°C in an atmospheric environment, keeping the temperature at 160°C to 200°C for 1min to 10min, and then cooling to room temperature at a cooling rate of 1°C / min to 10°C / 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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