阅读说明：本技术 一种分段热电器件连接用焊片及其制备方法 (Soldering lug for connecting segmented thermoelectric device and preparation method thereof ) 是由 李小亚 王维安 顾明 夏绪贵 廖锦城 吴洁华 邢云飞 陈立东 于 2019-10-17 设计创作，主要内容包括：本发明涉及一种分段热电器件连接用焊片及其制备方法,所述焊片具有A/B/A三层结构,其中A为低熔点组元组成的金属层,B为低熔点组元和高熔点组元组成的混合层；所述低熔点组元选自铅及其合金、锡及其合金、铟及其合金、锌及其合金、铝及其合金中的至少一种,所述高熔点组元选自钛、铬、铁、钴、镍、铜、锗、锆、银、金、铂、碲、锑、铌、钴中的至少一种元素。本发明的A/B/A三层结构焊片是经过压力加工形成一个整体,可以自由裁剪,以及可以很方便地用于热电材料的连接和已成型的热电器件之间的连接。(The invention relates to a soldering lug for connecting a segmented thermoelectric device and a preparation method thereof, wherein the soldering lug has an A/B/A three-layer structure, wherein A is a metal layer consisting of low-melting-point components, and B is a mixed layer consisting of the low-melting-point components and high-melting-point components; the low-melting-point component is at least one of lead and alloy thereof, tin and alloy thereof, indium and alloy thereof, zinc and alloy thereof, and aluminum and alloy thereof, and the high-melting-point component is at least one of titanium, chromium, iron, cobalt, nickel, copper, germanium, zirconium, silver, gold, platinum, tellurium, antimony, niobium and cobalt. The A/B/A three-layer structure soldering lug is formed into a whole through pressing, can be freely cut, and can be conveniently used for connecting thermoelectric materials and connecting formed thermoelectric devices.)

1. The soldering lug for connecting the segmented thermoelectric device is characterized by having an A/B/A three-layer structure, wherein A is a metal layer consisting of low-melting-point components, and B is a mixed layer consisting of the low-melting-point components and high-melting-point components; the low-melting-point component is at least one of lead and alloy thereof, tin and alloy thereof, indium and alloy thereof, zinc and alloy thereof, and aluminum and alloy thereof, and the high-melting-point component is at least one of titanium, chromium, iron, cobalt, nickel, copper, germanium, zirconium, silver, gold, platinum, tellurium, antimony, niobium and cobalt.

2. The bonding pad according to claim 1, wherein the mass ratio of the low-melting-point component to the high-melting-point component in the mixed layer is 1: (0.20 to 2.5).

3. The bonding pad according to claim 1 or 2, wherein the metal layer has a thickness of 5 to 100 μm.

4. The solder tab according to any one of claims 1 to 3, wherein the thickness of the mixed layer is 10 to 200 μm.

5. A method for producing a segmented thermoelectric device bonding pad according to any one of claims 1 to 4, comprising:

(1) weighing and mixing low-melting-point component powder and high-melting-point component powder according to the mass ratio to obtain mixed powder;

(2) and sequentially placing the metal layer consisting of the low-melting-point components and the mixed powder in a die and a press according to the A/B/A structure, and performing compression molding under the pressure of 10-50 MPa to obtain the soldering lug for connecting the segmented thermoelectric device.

6. The preparation method according to claim 5, wherein the particle size of the low-melting-point component powder is 0.1-100 μm; the grain size of the high-melting-point component powder is 0.1-100 mu m.

7. The preparation method according to claim 5 or 6, wherein the mixing is mechanical mixing, the rotation speed of the mechanical mixing is 50-300 r/min, and the time is 10-30 hours.

8. The method according to any one of claims 5 to 7, wherein the mixed powder is added in an amount of 0.05 to 0.3g/cm with respect to the area of the upper surface of the metal layer ²。

9. The production method according to any one of claims 5 to 8, wherein the metal layer composed of the low-melting-point component is a metal foil layer composed of the low-melting-point component or a metal coating layer formed of a low-melting-point component powder composition coating material A.

10. The production method according to claim 9, wherein the coating material a contains a low-melting-point component powder and an organic solvent selected from at least one of alcohol, acetone, diethyl ether, methanol, and carbon tetrachloride.

Technical Field

The invention relates to a soldering lug for connecting a segmented thermoelectric device and a preparation method thereof, belonging to the technical field of thermoelectric power generation.

Background

The thermoelectric power generation technology directly converts heat energy into electric energy by utilizing the Seebeck effect of a thermoelectric semiconductor material, has the characteristics of small system volume, compact structure, no movable part, no maintenance, no noise, no emission, high reliability, long service life and the like, is applied to deep space detection power supplies and special military power supplies, and has wide application prospect and potential economic and social benefits in the aspects of solar photoelectric-thermoelectric composite power generation and industrial waste heat, particularly automobile exhaust waste heat recovery thermoelectric power generation.

The thermoelectric device, a key component of the thermoelectric power generation technology, mainly comprises a p-type n-type thermoelectric material, an electrode and an electrically insulating ceramic substrate. The thermoelectric conversion efficiency is as follows:

depending on the temperature difference (T) between the high temperature side and the low temperature side of the thermoelectric material _H-T _C) And a nondimensional thermoelectric performance figure of merit, ZT, of the thermoelectric material. Thermoelectric materials are classified into high-temperature, medium-temperature, and low-temperature thermoelectric materials according to the use temperature range. Averaging using thermoelectric materials in general

Namely the integral area of the ZT-T curve, and calculating the thermoelectric conversion efficiency; up to now, the single material has low thermoelectric conversion efficiency, and the fresh one exceeds 10 percent ^[1](ii) a If the design of the segmented thermoelectric material with wide temperature range is carried out, the design can be carried outTo significantly improve

Thereby improving the thermoelectric conversion efficiency of the thermoelectric device ^[2]。

Common thermoelectric materials, such as high-temperature silicon germanium, medium-temperature lead telluride, low-temperature bismuth telluride and the like, have mature device technologies, and products have been put into practical application, but the high-efficiency wide-temperature-range segmented thermoelectric device technology is in the research and development stage, and the key is the connection technology of the segmented thermoelectric devices, including connection between segmented thermoelectric material elements, namely high-temperature/medium-temperature, medium-temperature/low-temperature, high-temperature/medium-temperature/low-temperature thermoelectric material elements, and connection between the high-temperature thermoelectric material elements and electrodes. Sejin Yoon et al ^[3]It is reported that a discharge plasma sintering technology is adopted to link two thermoelectric materials of n-type bismuth telluride/lead telluride, but a sintering method cannot prepare a segmented thermoelectric device. Patent application ^[4]The method is characterized in that a welding method is adopted to prepare three sections of thermoelectric devices, different solders are sequentially adopted to carry out four times of welding from a high-temperature end to a low-temperature end, the materials and the structure of the devices bear thermal cycle, and the local part of the heterostructure of the devices can generate stress concentration, so that the reliability of the devices is reduced, and even the devices are cracked locally and fail; the welding temperature is far higher than the use temperature of the thermoelectric material, which can cause the performance of the temperature-sensitive thermoelectric material to be damaged, and the thermoelectric conversion efficiency of the device is reduced; the common welding method is brazing or diffusion welding, the welding temperature is a fixed value, and if different thermoelectric materials are replaced, different welding materials need to be replaced, the process is complex and the cost is high; and the requirement on the consistency of the height of the original thermoelectric material is strict, if the thermoelectric element has height deviation, local cold joint can be caused, the method has complex process, and the multi-section thermoelectric device is difficult to prepare in a large scale. Patent application ^[5,6]The method belongs to mechanical contact, the contact resistance and the contact thermal resistance of the device interface are high, and the thermoelectric conversion efficiency of the device is greatly reduced. In summary, the conventional sintering, welding and crimping methods are difficult to solve the problems of the link of the segmented thermoelectric device without reducing the performance and the like.

Patent documents:

[1]Zhang Q.H.,Huang X.Y.,Bai,S.Q.,Shi X.,Uher C.,Chen L.D.,ThermoelectricDevices for Power Generation:Recent Progress and Future Challenges,AdvancedEngineering Materials 2016,18:194-213.

[2]Ou Yang.,Li.D.,Modelling of segmented high-performance thermoelectricgenerators with effects of thermal radiation,electrical and thermal contactresistances,Scientific Reports 2016,6:1-12.

[3]Sejin Yoon,Jun-Young Cho,Hyun Koo,Thermoelectric Properties of n-TypeBi ₂Te ₃/PbSe _0.5Te _0.5Segmented Thermoelectric Material,Journal of Electronicmaterials 2013,41:414-418.

[4] chinese patent publication No. CN 107681044 a;

[5] chinese patent publication No. CN 103022338A;

[6] chinese patent publication No. CN 105006517A.

Disclosure of Invention

The invention provides a soldering lug for connecting a segmented thermoelectric device and a preparation method thereof, aiming at solving the problems of the existing soldering flux for connecting the segmented thermoelectric device.

In one aspect, the present invention provides a soldering lug for connecting a segmented thermoelectric device, the soldering lug having an a/B/a three-layer structure, wherein a is a metal layer composed of a low melting point component, and B is a mixed layer composed of a low melting point component and a high melting point component; the low-melting-point component is at least one of lead and alloy thereof, tin and alloy thereof, indium and alloy thereof, zinc and alloy thereof, and aluminum and alloy thereof, and the high-melting-point component is at least one of titanium, chromium, iron, cobalt, nickel, copper, germanium, zirconium, silver, gold, platinum, tellurium, antimony, niobium and cobalt.

In the present disclosure, the tab has an a/B/a three-layer structure (a is a low-melting-point metal foil or coating (low-melting-point component), and B is a mixture of low-melting-point component powder and high-melting-point component powder). In the subsequent connection process, the low-melting-point metal foil (or coating) in the soldering lug is melted with the powder in the mixed layer to realize the connection of the segmented thermoelectric material, and in the subsequent heat treatment process, the low-melting-point component in the mixed layer and the layer A simultaneously reacts with the high-melting-point powder to generate a high-melting-point intermetallic compound, so that the joint is ensured to be stable at a higher use temperature, and the low-temperature connection and high-temperature application of the segmented thermoelectric device are realized. The soldering lug is used for connecting the segmented thermoelectric device, so that the connection temperature can be reduced, the connection tool is simplified, the connection times are reduced, the connection process of the segmented thermoelectric device is simple, the operation is convenient, the time is saved, and the damage of high-temperature electrode connection to medium-temperature and low-temperature thermoelectric materials and the adverse effect of thermal stress on the reliability of the device can be avoided.

Preferably, the mass ratio of the low-melting-point component to the high-melting-point component in the mixed layer is 1: (0.20 to 2.5).

Preferably, the thickness of the metal layer is 5 to 100 μm.

Preferably, the thickness of the mixed layer is 10 to 200 μm.

In another aspect, the present invention provides a method for preparing the soldering lug for connecting a segmented thermoelectric device, including:

(1) weighing and mixing low-melting-point component powder and high-melting-point component powder according to the mass ratio to obtain mixed powder;

(2) and sequentially placing the metal layer consisting of the low-melting-point components and the mixed powder in a die and a press according to the A/B/A structure, and performing compression molding under the pressure of 10-50 MPa to obtain the soldering lug for connecting the segmented thermoelectric device.

Preferably, the particle size of the low-melting-point component powder is 0.1-100 μm; the grain size of the high-melting-point component powder is 0.1-100 mu m.

Preferably, the mixing mode is mechanical mixing, the rotating speed of the mechanical mixing is 50-300 r/min, and the time is 10-30 h.

Preferably, the addition amount of the mixed powder is 0.05-0.3 g/cm relative to the area of the upper surface of the metal layer ²。

Preferably, the metal layer composed of the low-melting-point component is a metal foil layer composed of the low-melting-point component or a metal coating layer formed by a coating A composed of low-melting-point component powder.

The coating material A contains low-melting-point component powder and an organic solvent, wherein the organic solvent is at least one selected from alcohol, acetone, methanol, diethyl ether and carbon tetrachloride.

Compared with the prior art, the invention has the beneficial effects that:

(1) the A/B/A three-layer structure soldering lug is processed by pressure to form a whole, can be freely cut, and can be conveniently used for connecting thermoelectric materials and connecting formed thermoelectric devices;

(2) by adopting the soldering lug for connecting the segmented thermoelectric device, a plurality of joints of the segmented thermoelectric device can be connected at the same time, a plurality of different solders are not required to be selected, a mould is not required to be used, and the connecting procedure is simplified to a great extent;

(3) for three or more sections of thermoelectric devices, the soldering lug for connecting the segmented thermoelectric devices does not need to be welded for many times, so that the adverse effect of the circulating thermal stress on the devices is avoided;

(4) by adopting the soldering lug for connecting the segmented thermoelectric device, the performance of the thermoelectric material cannot be damaged due to overheating during welding;

(5) the soldering lug for connecting the segmented thermoelectric device has certain height self-adaptive performance, and the melting of the low-melting-point metal foil (or coating) can make up for the slight difference of the heights of the thermoelectric elements, so that the condition of insufficient soldering cannot be caused;

(6) the soldering lug for connecting the segmented thermoelectric device has temperature adaptability, when the thermoelectric material is replaced, a proper soldering material does not need to be selected again, and the soldering lug is very suitable for connecting the segmented thermoelectric device;

(7) by adopting the soldering lug for connecting the segmented thermoelectric device, the low-temperature connection and high-temperature application of the segmented thermoelectric device can be realized.

Drawings

FIG. 1 is a schematic diagram of a method for manufacturing a solder pad according to the present invention;

FIG. 2 is a phase diagram of a nickel-tin alloy;

FIG. 3 is a photograph of a solder piece with a three-layer structure of tin/nickel-tin/tin prepared by the present invention;

FIG. 4 shows Ni formed after heat treatment of a joint for connecting a half-heusler (HH) and Skutterudite (SKD) thermoelectric material using the bonding pad of the present invention ₃A Sn high temperature phase;

FIG. 5 is a tellurium-tin alloy phase diagram;

FIG. 6 is a phase diagram of a lead-zirconium alloy;

FIG. 7 is a phase diagram of an indium-nickel alloy;

FIG. 8 is a phase diagram of a zinc zirconium alloy.

Detailed Description

The present invention is further illustrated by the following examples, which are to be understood as merely illustrative and not restrictive.

The invention aims to overcome the defects of the existing segmented thermoelectric device connection technology and is dedicated to research and development of a soldering lug with strong adaptability for low-temperature connection and high-temperature application of the segmented thermoelectric device. In the disclosure, the soldering lug for connecting the segmented thermoelectric device is a three-layer structure of A/B/A, wherein A is a metal foil or a metal coating composed of low-melting-point components, and B is a mixed layer composed of low-melting-point component metal powder and high-melting-point component powder. In the connection process of the segmented thermoelectric device, the low-melting-point metal foil (or metal coating) of the soldering lug and the powder in the mixed layer are melted to connect the segmented thermoelectric material, and are diffused in the subsequent heat treatment process to generate intermetallic compounds with high melting point and good thermal stability with high-melting-point powder, so that the low-temperature connection and high-temperature application of the segmented thermoelectric device are realized.

In an alternative embodiment, the metal foil (or metal coating) of the low melting point component is selected from at least one of tin, indium, lead, zinc, aluminum, and the like, and alloys thereof. The thickness of the metal foil (or the metal coating) may be 5 to 100 μm.

In an alternative embodiment, the mass ratio of the low-melting-point metal powder to the high-melting-point metal powder in the mixed layer may be 1: (0.25-2.5). The thickness of the mixed layer can be 20 to 200 μm. Wherein the low-melting-point metal powder is at least one selected from lead, tin, indium, zinc, aluminum and alloys thereof. The high melting point metal powder is at least one element selected from titanium, chromium, iron, cobalt, nickel, copper, germanium, zirconium, silver, gold, platinum, tellurium, antimony, niobium, cobalt and the like. The particle size of the low-melting point metal powder and the high-melting point metal powder can be 0.1-100 μm.

The principle of the preparation method of the soldering lug for connecting the segmented thermoelectric device is shown in figure 1. The following exemplarily illustrates a method for preparing a bonding pad for segmented thermoelectric device connection provided by the present invention.

A metal foil (or metal coating) composed of a suitable low-melting-point component is selected as a according to the use temperature of the segmented thermoelectric material. The metal coating can be prepared from the coating A containing the low-melting-point component powder by coating modes such as spraying, dipping, brushing and the like. Wherein, the coating comprises low-melting-point component powder and an organic solvent. The organic solvent can be ethanol, acetone, diethyl ether, methanol, carbon tetrachloride, etc. The particle size of the low-melting-point component powder can be 0.1-100 mu m.

As an example of a method for preparing the coating material, the selected low-melting metal powder is placed in a container, a volatile organic solvent is added, and stirring (such as mechanical stirring, electromagnetic stirring, and the like) is performed to uniformly disperse the powder in the organic solvent, so as to obtain the coating material A (or called slurry A).

According to the using temperature of the segmented thermoelectric material, proper low-melting-point component powder and high-melting-point component powder are selected, the powder is prepared according to the proportion of high-temperature phases generated by phase diagrams of the low-melting-point component powder and the high-melting-point component powder and is placed in a mixer for mixing, and uniformly mixed powder (mixed powder for short) is obtained. The mass ratio of the low-melting-point component powder to the high-melting-point component powder can be 1: (0.25-2.5). The particle size of the powder is 0.1 to 100 μm. As an example of the mass ratio of the mixed powder, the prepared low-melting-point metal powder and high-melting-point metal powder are placed in a mixer and mechanically mixed for 10-30 hours at the speed of 50-300 r/min to obtain uniform mixed powder. Preferably, the organic solvent is added in the mixing process, so that the low-melting-point metal powder and the high-melting-point metal powder are uniformly dispersed, and uniform mixed powder is obtained after the organic solvent is volatilized. For example, the Sn content in the nickel-tin mixed powder may be 40.3 wt% and 57.4 wt%. The content of Sn in the tellurium-tin mixed powder can be 48.2 wt%.

Weighing a certain weight of mixed powder, and uniformly spreading the mixed powder on a low melting pointAnd a layer of metal foil is covered on the metal foil consisting of the point components. Wherein the addition amount of the mixed powder can be 0.05-0.3 g/cm ²。

And (2) placing the metal foil (A) and the mixed powder (B) in a die and a press according to the sequence of A/B/A, and plastically deforming the metal foil and the mixed powder under high pressure to form the soldering lug for connecting the segmented thermoelectric device. Or placing the prepared mixed powder in a die and a press, high-pressure tabletting, coating the prepared coating A, and obtaining a soldering lug after the organic solvent is completely volatilized; the coating mode can be as follows: spraying, dipping and brushing.

In alternative embodiments, the high pressure forming method includes cold isostatic pressing, electromagnetic powder pressing, discharge impact pressing, rolling, etc. during the tab making process. The molding pressure can be 10-50 MPa, and the holding time can be 5-20 minutes.

In one embodiment of the invention, the obtained soldering lug is used for welding thermoelectric materials, and a high-temperature stable compound is formed after heat treatment, so that the requirements of low-temperature connection and high-temperature application of the segmented thermoelectric device are met. The soldering lug is an ABA three-layer structure formed by high-pressure compaction of low-melting-point metal and alloy foil or coating (A) thereof and mixed powder (B) of low-melting-point metal and alloy powder thereof and high-melting-point component powder, and low-temperature connection and high-temperature application of a thermoelectric device are realized by melting the low-melting-point metal and alloy foil thereof or coating (A) and powder (B) thereof and reacting with the high-melting-point component to generate a high-melting-point metal bond compound.

The present invention will be described in further detail with reference to examples. It is also to be understood that the following examples are illustrative of the present invention and are not to be construed as limiting the scope of the invention, and that certain insubstantial modifications and adaptations of the invention by those skilled in the art may be made in light of the above teachings. The specific process parameters and the like of the following examples are also only one example of suitable ranges, i.e., those skilled in the art can select the appropriate ranges through the description herein, and are not limited to the specific values exemplified below.