WO2022169072A1

WO2022169072A1 - Element comprising diffusion prevention structure and junction layer formed via electroplating, and method for manufacturing same

Info

Publication number: WO2022169072A1
Application number: PCT/KR2021/016054
Authority: WO
Inventors: 김세일; 나종주; 이주열; 이주영; 좌용호
Original assignee: 한국재료연구원
Priority date: 2021-02-08
Filing date: 2021-11-05
Publication date: 2022-08-11
Also published as: KR20220115664A

Abstract

The present invention relates to an element comprising a diffusion prevention structure and a junction layer formed via electroplating, and a method for manufacturing same. More specifically, the present invention relates to an element comprising a diffusion prevention structure and a junction layer formed via electroplating, and a method for manufacturing same, which have an excellent junction performance, prevent peeling and cracking, and enable large-scale mass production at a low cost.

Description

Device comprising a bonding layer formed by an electroplating method and a diffusion preventing structure and method for manufacturing the same

The present invention relates to a device including a bonding layer formed by an electroplating method and a diffusion preventing structure, and a method for manufacturing the same. More specifically, the present invention relates to a device including a bonding layer and a diffusion prevention structure formed by an electroplating method having excellent bonding performance, preventing peeling and cracking, and capable of mass-producing large-area at low cost, and a method for manufacturing the same.

Ceramics have greater strength at high temperatures and lower thermal conductivity and thermal expansion coefficient than metals. application is limited.

Therefore, in order to improve the performance of ceramics with low machinability and reliability and to expand the range of applications, they should be used in combination with metals. However, the bonding problem between the metal and the ceramic and the performance degradation due to the diffusion of the component materials at a high temperature act as a major problem in using the same. For this purpose, it is important to fabricate a device having a diffusion prevention structure while having excellent bonding performance, rather than fabricating a layer capable of only good bonding or only diffusion prevention that does not consider bonding.

Meanwhile, in the case of medium-temperature thermoelectric power generation, it is a field that has been actively developed until recently in response to the rapid development of thermoelectric materials and the demand for recovery of a vast amount of waste heat resources wasted. In particular, in the transportation field, about 40% of energy is wasted as waste heat, and in order to recover it, increase fuel efficiency and reduce carbon dioxide generation, the development of a medium temperature thermoelectric power module is inevitable.

At the junction interface between the heterogeneous junction thermoelectric material and the metal layer, various diffusion phenomena occur near the operating temperature of the thermoelectric module for medium temperature of 400 to 600°C. Such diffusion causes a secondary growth in the thickness of the diffusion layer, resulting in a serious long-term reliability problem in that the power generation output is reduced due to a decrease in the proportion of thermoelectric materials in the thermoelectric module. In addition to the module output decrease, when the thermal expansion coefficient of the generated diffusion layer has a large gap with the thermoelectric material and electrode forming the original interface, cracks occur on the bonding surface, which causes serious problems.

The currently mainly used method for manufacturing a diffusion barrier layer (metallization layer) for a medium temperature thermoelectric element is to raise a powder, foil, or plate of a material to be used as a diffusion barrier layer on top of the medium temperature thermoelectric material powder, and discharge plasma sintering ( Intermetallic compound (IMC) is formed by sintering by Spark Plasma Sintering (SPS) method.

When the above method is used, there are major disadvantages in that 1) the process cost is high, and 2) the mass and continuous process are difficult due to the characteristics of the SPS process using high temperature and high pressure. In addition, since a large amount of diffusion barrier layer material is used in the process, the unit price may increase and price competitiveness may decrease.

As a background art of the present invention, there is Republic of Korea Patent Publication No. 10-1983627.

It is an object of the present invention to provide a device having an excellent bonding performance and a diffusion preventing structure.

Another object of the present invention is to provide a medium temperature thermoelectric device that prevents peeling and cracks and can be mass-produced over a large area at low cost.

Another object of the present invention is to provide a method for manufacturing a medium-temperature thermoelectric element capable of mass-producing a large-area medium-temperature thermoelectric element at low cost through a simple process.

The object of the present invention is not limited to the objects mentioned above, and other objects not mentioned will be clearly understood from the description of the detailed description.

According to one aspect, the first material; second material; and a bonding layer and a diffusion prevention structure between the first material and the second material, wherein the bonding layer and the diffusion prevention structure are composed of an intermetallic compound of the first material material and the second material material, and the second material a first layer in contact with the material; and a second layer made of a material forming an intermetallic compound with the first material and formed on the first layer.

According to another aspect, the substrate unit; thermoelectric material unit; and a diffusion barrier layer formed between the substrate unit and the thermoelectric material unit, wherein the diffusion barrier layer includes: a first layer made of an intermetallic compound of a first material and a second material and in contact with the thermoelectric material unit; and a second layer formed of the first material and a second material forming an intermetallic compound and formed on the first layer;

According to an embodiment, a difference between the coefficient of thermal expansion of the material constituting the thermoelectric material part and the coefficient of thermal expansion of the first material may be 5 x 10 ^-6 K ^-1 or less.

According to an embodiment, the material constituting the thermoelectric material part may be PbTe, the first material may be Te, and the second material may be Ni.

According to an embodiment, the material constituting the thermoelectric material part may be PbTe, the first material may be Sn, and the second material may be Cu.

According to an embodiment, the material constituting the thermoelectric material part may be PbTe, the first material may be Co, and the second material may be Fe.

According to an embodiment, the diffusion barrier layer may have a thickness of 0.5 to 10 μm.

According to an embodiment, the intermetallic compound of the first layer may be formed by heat treatment after plating a second material on the plating layer of the first material formed on the substrate part.

According to an embodiment, the material constituting the thermoelectric material part is prevented from being diffused into the diffusion barrier layer by the first material plating layer, so that the thermoelectric material part is more uniform than when the diffusion barrier layer formed by the SPS (Spark Plasma Sintering) process is formed. It can have one composition.

According to an embodiment, the second layer may be formed on an upper surface and both sides of the first layer.

According to another aspect, i) preparing a thermoelectric material part of a medium temperature thermoelectric element; and ii) forming a diffusion barrier layer formed of a first layer and a second layer on the thermoelectric material part, wherein step ii) includes ii-1) electroplating a first material on the thermoelectric material part forming a first material plating layer; ii-2) forming a second material plating layer by electroplating a second material forming an intermetallic compound with the first material on the first material plating layer; and ii-3) a first layer comprising an intermetallic compound of a first material and a second material by heat treatment and in contact with the thermoelectric material part; and forming a second layer made of only a second material and formed on the first layer.

According to an embodiment, in the method of manufacturing a medium temperature thermoelectric element, a difference between a coefficient of thermal expansion of a material constituting the thermoelectric material part and a coefficient of thermal expansion of the first material may be 5 x 10 ^-6 K ^-1 or less.

According to an embodiment, in the method for manufacturing a medium temperature thermoelectric element, the material constituting the thermoelectric material part may be PbTe, the first material may be Te, and the second material may be Ni.

According to an embodiment, in the method of manufacturing a medium temperature thermoelectric element, the material constituting the thermoelectric material part may be PbTe, the first material may be Sn, and the second material may be Cu.

According to an embodiment, in the method of manufacturing a medium temperature thermoelectric element, the material constituting the thermoelectric material part may be PbTe, the first material may be Co, and the second material may be Fe.

According to one embodiment, in the medium temperature thermoelectric device manufacturing method, the material constituting the thermoelectric material part is prevented from being diffused into the diffusion barrier layer by the first material plating layer in step ii), formed by a spark plasma sintering (SPS) process The thermoelectric material part may have a more uniform composition than in the case where the diffusion barrier layer is formed.

According to one embodiment, there is provided a method for manufacturing a medium temperature thermoelectric device, the method comprising: electroplating a second material on an upper surface of the first material plating layer; and electroplating the second material so that the second layer is formed on the upper surface and both sides of the first layer.

According to one embodiment, the present application may provide a device having an excellent bonding performance and a diffusion preventing structure.

According to one embodiment, the present application includes a diffusion prevention layer composed of an electroplating layer having a similar thermal expansion coefficient to that of the thermoelectric material portion, thereby preventing peeling and cracking and providing a medium temperature thermoelectric device having a uniform and thin diffusion prevention layer.

According to one embodiment, the present application may provide a medium temperature thermoelectric device manufacturing method capable of mass-producing a large area medium temperature thermoelectric device at low cost through a simple process.

1A and 1B are schematic views showing the structure of a thermoelectric element.

2 is a schematic diagram schematically showing a method of forming a diffusion barrier layer for a medium temperature thermoelectric element by an electroplating method according to an embodiment of the present invention.

3 is a schematic diagram schematically showing a method of forming a Ni _x Te _y diffusion barrier layer for a medium temperature thermoelectric device by an electroplating method according to an embodiment of the present invention.

4A is a graph showing the coefficient of thermal expansion (CTE) of PbTe.

4B is a graph showing the coefficient of thermal expansion (CTE) of nickel.

5 is a photograph showing a phenomenon in which a nickel layer is peeled off when a nickel layer is formed as a diffusion barrier layer by an electroplating process and then heat treated.

6 is a graph showing X-ray diffraction patterns of a Ni _x Te _y diffusion barrier layer for a medium temperature thermoelectric element formed by an electroplating method according to an embodiment of the present invention.

7 is a photograph showing the results of an adhesion test of a Ni _x Te _y diffusion barrier layer for a medium temperature thermoelectric device formed by an electroplating method according to an embodiment of the present invention.

Objects, specific advantages and novel features of the present disclosure will become more apparent from the following detailed description and embodiments taken in conjunction with the accompanying drawings.

Prior to this, the terms or words used in the present specification and claims should not be construed in a conventional and dictionary meaning, and the inventor may properly define the concept of the term to describe his invention in the best way. Based on the principle that there is, it should be interpreted as meaning and concept consistent with the technical idea of the present disclosure.

In this specification, when a component, such as a layer, portion, or substrate, is described as being “on,” “connected with,” or “coupled to” another component, it is directly “on”, “coupled to” the other component. It may be "connected" or "coupled", and one or more other elements may be interposed between both elements. In contrast, when an element is described as being “directly on,” “directly connected to,” or “directly coupled to,” another element, no other element may be interposed between the two elements. .

The terms used herein are used only to describe specific embodiments, and are not intended to limit the present disclosure. The singular expression includes the plural expression unless the context clearly dictates otherwise.

In the present specification, terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It is to be understood that this does not preclude the possibility of the presence or addition of numbers, steps, operations, components, parts, or combinations thereof.

In the present specification, when a part "includes" a certain component, this means that other components may be further included rather than excluding other components unless otherwise stated. In addition, throughout the specification, "on" means to be located above or below the target part, and does not necessarily mean to be located above the direction of gravity.

Since the present disclosure can apply various transformations and can have various embodiments, specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present disclosure to specific embodiments, and it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present disclosure. In describing the present disclosure, if it is determined that a detailed description of a related known technology may obscure the gist of the present disclosure, the detailed description thereof will be omitted.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings, and in the description with reference to the accompanying drawings, the same or corresponding components are given the same reference numerals, and the overlapping description thereof will be omitted. do.

The first material and the second material may be all materials and metals except for metals and plastics, but are not limited thereto, but the first material may be a ceramic, and the second material may be a metal.

The bonding layer and the diffusion preventing structure are composed of an intermetallic compound of the first material material and the second material material, and a first layer in contact with the second material and a material forming an intermetallic compound with the first material, Including the second layer formed on the first layer, the first material and the second material composed of two materials having different physical and chemical properties have a structure in which a transition region, that is, an interface product, is formed that can provide compatibility between the first material and the second material.

Therefore, it is possible to provide a device capable of preventing diffusion while having excellent bonding performance, although it is not a layer structure in which only bonding is excellent or only diffusion prevention is possible without considering bonding.

The device may be a thermoelectric device in which a diffusion barrier layer serving as a bonding material is formed while preventing material movement between the thermoelectric material and the electrode. In addition, the device structure may be applied to a power semiconductor device. That is, it can be applied to the manufacture of a solder material (eg Cu-Sn) bonding to DBC (direct bond copper, Cu/Al ₂ O ₃ /Cu) of a power semiconductor device.

Furthermore, when the ceramic and the metal are joined, the miniaturization and surface mounting of the parts are possible, so that it is possible to manufacture components having a complex shape having various functions. Accordingly, the device structure can be applied to sensors, microelectronic component circuits, MEMS, high-efficiency heat exchangers, and electronic product packaging fields.

According to another aspect, the substrate portion; thermoelectric material unit; and a diffusion barrier layer formed between the substrate unit and the thermoelectric material unit, wherein the diffusion barrier layer includes: a first layer made of an intermetallic compound of a first material and a second material and in contact with the thermoelectric material unit; and a second layer formed of the first material and a second material forming an intermetallic compound and formed on the first layer;

Referring to FIGS. 1A and 1B , the medium temperature thermoelectric element largely includes a substrate part 100 , a thermoelectric material part 200 , and a diffusion barrier layer 300 .

The thermoelectric material part 200 is a part that generates electricity by receiving heat, and may include two or more thermoelectric materials. The type of the thermoelectric material part 200 is not particularly limited as long as it can generate electricity by receiving heat. For example, it may be composed of PbTe.

The substrate part 100 is a part for arranging and fixing the thermoelectric material part 200 . As shown in FIG. 1A , it may include a ceramic substrate 110 , a Cu electrode 120 , and a blazing filter 130 . The blazing filter 130 is a layer for bonding the Cu electrode 120 and the diffusion barrier layer 300 .

The diffusion barrier layer 300 is a metallization layer for bonding both between the thermoelectric material part 200 and the substrate part 100, and the material of the thermoelectric material 200 and the material of the substrate part 100 is They diffuse to each other and serve to prevent degradation.

2 is a schematic diagram schematically showing a method of forming a diffusion barrier layer for a medium temperature thermoelectric element by an electroplating method according to an embodiment of the present invention. 3 is a schematic diagram schematically showing a method of forming a Ni _x Te _y diffusion barrier layer for a medium temperature thermoelectric device by an electroplating method according to an embodiment of the present invention.

Referring to FIGS. 2 and 3 , the diffusion barrier layer 300 includes a first layer 330 made of an intermetallic compound of a first material and a second material and in contact with the thermoelectric material unit 200 ; and a second layer (322) made of a second material forming an intermetallic compound with the first material and formed on the first layer.

As described above, the first layer 330 and the second layer 322 in contact with the thermoelectric material part 200 are made of different materials to suppress cracks and peeling compared to the diffusion prevention layer 300 formed as a single layer. can do.

The intermetallic compound of the first layer 330 may be formed by heat treatment after forming the second material plating layer 320 on the first material plating layer 310 formed on the thermoelectric material part 200 .

Diffusion of the material constituting the thermoelectric material part 200 into the diffusion barrier layer 300 is prevented by the first material plating layer 310, and a diffusion barrier layer formed by a spark plasma sintering (SPS) process is formed. The thermoelectric material unit 200 may have a uniform composition.

Although not limited thereto, the difference between the coefficient of thermal expansion (CTE) of the material constituting the thermoelectric material part 200 and the coefficient of thermal expansion of the first material is 5 x 10 ^-6 K ^-1 or less crack Or it may be suitable for suppressing the occurrence of peeling. If the coefficient of thermal expansion of the diffusion barrier layer 300 deposited on the thermoelectric material part 200 for medium temperature differs greatly from the coefficient of thermal expansion of the thermoelectric material part 200, peeling or cracking may occur at the device driving temperature (500 to 600 ℃). high portential. Therefore, in the present invention, the ^{thermoelectric} ^material unit ( By forming the first layer 330 in contact with the 200), it is possible to suppress the occurrence of cracks or peeling.

The material constituting the thermoelectric material part 200 may be PbTe, the first material may be Te, and the second material may be Ni. The thermal expansion coefficient of the PbTe is constant from 300K (26.85° C.) to about 20×10 ⁻⁶ K ⁻¹ (see FIG. 4a ). On the other hand, the thermal expansion coefficient of nickel is about 13 x 10 ^-6 K ^-1 at room temperature, and about 16-17 x 10 ^-6 K ^-1 at 400 to 600 °C, so the difference in thermal expansion coefficient with PbTe is 4 x 10 ^-6 more than K ^-1 . There may be a problem of peeling during heat treatment at a driving temperature (600° C.) (see FIG. 5 ). Accordingly, in the present application, the peeling or cracking problem can be solved by forming the plating layer 310 of the first material with Te having a thermal expansion coefficient of about 19 x 10 ^-6 K ^-1 similar to PbTe.

In addition, the material constituting the thermoelectric material part 200 may be PbTe, the first material may be Sn, and the second material may be Cu. By forming the first material plating layer 310 of Sn having a thermal expansion coefficient of about 20 x 10 ^-6 K ^-1 similar to that of PbTe, the problem of peeling or cracking of the thermoelectric material part 200 and the diffusion barrier layer 300 can be solved. . In this case, Sn-Cu must maintain a solid phase above the PbTe driving temperature of 600 °C (medium temperature region). In order to maintain the solid phase at 600℃ or higher through the phase diagram, it may be suitable for Cu to have a range of about 75~90% in the Sn-Cu alloy. On the other hand, when the Sn-Cu alloy is electroplated at once and deposited on PbTe, the electrode is highly likely to fall off due to the difference in the coefficient of thermal expansion between the two.

In addition, the material constituting the thermoelectric material part 200 may be PbTe, the first material may be Co, and the second material may be Fe. Co (cobalt; 13 x 10 ^-6 /℃) and Fe (iron; 11.7 x 10 ^-6 /℃) are sequentially formed by electroplating as a first material plating layer 310 and a second material plating layer 320, followed by heat treatment Thus, it is possible to form a Co-Fe diffusion barrier layer.

Although not limited thereto, the diffusion barrier layer may have a thickness of 0.5 to 30 μm. Even though the diffusion barrier layer of the present application is thin, the material constituting the thermoelectric material part 200 is prevented from being diffused into the diffusion barrier layer 300 by the first material plating layer 310 of the first material as described above. Material properties can be improved. In the case of the conventional SPS process, Ni powder is coated on the PbTe powder, which is a thermoelectric material, to form an electrode layer, and Ni _x Te _y is formed as Te and Ni powder of the thermoelectric material are diffused through the heat treatment process. In this case, since Te can escape from PbTe, PbTe rich in Pb is formed, rather than having a PbTe composition, on the upper side, which may adversely affect the properties of the thermoelectric material. However, in the present invention, by depositing a Te plating layer on the bulk PbTe first, it is possible to prevent Te from escaping from the PbTe, thereby improving the properties of the thermoelectric material.

Although not limited thereto, the second layer 322 may be formed on the upper surface and both sides of the first layer 330 . According to the above configuration, the bonding strength between the diffusion barrier layer 300 and the thermoelectric material unit 200 can be further improved.

2 to 3 , a method for manufacturing a medium temperature thermoelectric element according to another aspect includes the steps of: i) preparing a thermoelectric material unit 200 of the medium temperature thermoelectric element; and ii) forming a diffusion barrier layer 300 formed of a first layer 330 and a second layer 322 on the thermoelectric material unit 200, wherein step ii) is ii-1) forming a first material plating layer 310 by electroplating a first material on the thermoelectric material unit 200; ii-2) forming a second material plating layer 320 by electroplating a second material forming an intermetallic compound with the first material on the first material plating layer 310; and ii-3) a first layer 330 made of an intermetallic compound of a first material and a second material by heat treatment and in contact with the thermoelectric material part 200 ; and forming a second layer 322 made of only a second material and formed on the first layer.

The present invention is a second method capable of forming an intermetallic compound by first plating a material used as a thermoelectric material (eg, PbTe) and a material having a small difference in thermal expansion coefficient and reacting with the first plating material during heat treatment It is characterized in that the process of manufacturing the diffusion barrier layer by plating the material.

Step i) is a step of preparing the thermoelectric material part 200 of the medium temperature thermoelectric element. The type of the constituent material of the thermoelectric material unit 200 is not particularly limited as long as it receives heat to generate electricity. For example, the thermoelectric material part 200 may be made of PbTe.

In the medium temperature thermoelectric device manufacturing method, the difference between the thermal expansion coefficient of the material constituting the thermoelectric material part 200 and the thermal expansion coefficient of the first material may be 5 x 10 ^-6 K ^-1 or less, but is not limited thereto. According to the above configuration, it may be suitable for suppressing the occurrence of cracks or peeling of the diffusion barrier layer 300 .

In the medium temperature thermoelectric device manufacturing method, the material constituting the thermoelectric material part 200 may be PbTe, the first material may be Te, and the second material may be Ni. The thermal expansion coefficient of the PbTe is constant from 300K (26.85° C.) to about 20×10 ⁻⁶ K ⁻¹ (see FIG. 4a ). In contrast, the thermal expansion coefficient of nickel is about 13 x 10 ^-6 K ^-1 at room temperature, and about 16-17 x 10 ^-6 K ^-1 at 400 to 600 °C, so the difference in thermal expansion coefficient with PbTe is 4 x 10 ^-6 K ^-1 or more. There may be a problem of peeling during heat treatment at a driving temperature (600° C.) (see FIG. 5 ). Accordingly, in the present application, the peeling or cracking problem can be solved by forming the plating layer 310 of the first material with Te having a thermal expansion coefficient of about 19 x 10 ^-6 K ^-1 similar to PbTe.

In addition, in the medium temperature thermoelectric device manufacturing method, the material constituting the thermoelectric material part 200 may be PbTe, the first material may be Sn, and the second material may be Cu. By forming the first material plating layer 310 of Sn having a thermal expansion coefficient of about 20 x 10 ^-6 K ^-1 similar to that of PbTe, the problem of peeling or cracking of the thermoelectric material part 200 and the diffusion barrier layer 300 can be solved. . In this case, Sn-Cu must maintain a solid phase above the PbTe driving temperature of 600 °C (medium temperature region). In order to maintain the solid phase at 600℃ or higher through the phase diagram, it may be suitable for Cu to have a range of about 75~90% in the Sn-Cu alloy. On the other hand, when the Sn-Cu alloy is electroplated at once and deposited on PbTe, the electrode is highly likely to fall off due to the difference in the coefficient of thermal expansion between the two.

In addition, in the medium temperature thermoelectric device manufacturing method, the material constituting the thermoelectric material part 200 may be PbTe, the first material may be Co, and the second material may be Fe. Co (cobalt; 13 x 10 ^-6 /℃) and Fe (iron; 11.7 x 10 ^-6 /℃) are sequentially formed as a first material plating layer 310 and a second material plating layer 320 by electroplating, followed by heat treatment Thus, it is possible to form a Co-Fe diffusion barrier layer.

In the medium temperature thermoelectric device manufacturing method, in step ii), the material constituting the thermoelectric material part 200 is prevented from being diffused into the diffusion barrier layer 300 by the first material plating layer 310, so that SPS (Spark Plasma Sintering) ), since the thermoelectric material part 200 may have a more uniform composition than in the case of forming the diffusion barrier layer formed by the above process, the characteristics of the thermoelectric material may be improved. More specifically, in the case of the conventional SPS process, Ni powder is applied on the PbTe powder to form an electrode layer, and Ni _x Te _y is formed while Te and Ni powder of the thermoelectric material material diffuse through the heat treatment process. In this case, since Te escapes from PbTe, which is a thermoelectric material, PbTe rich in Pb is formed, rather than having a PbTe composition, on the upper side, which may adversely affect the properties of the thermoelectric material. However, by depositing a Te plating layer on PbTe first, it is possible to prevent Te from escaping from PbTe, thereby improving the properties of the thermoelectric material.

Referring to FIG. 3 , in the method of manufacturing a medium temperature thermoelectric device, the method includes: electroplating to form a second material plating layer 320 with a second material on the upper surface of the first material plating layer 310 ; and electroplating the second material thin film 320 ′ such that the second layer 322 is formed on the upper surface and both sides of the first layer 330 . According to the above configuration, it may be suitable for suppressing the occurrence of cracks or peeling of the diffusion barrier layer 300 .

As in the method of manufacturing a thermoelectric element according to the present invention, in the case of a diffusion barrier layer manufactured through electroplating and heat treatment, the thickness may be about 0.5 to 10 μm. In the case of the SPS process, since the size of the powder used is large, it is difficult to form a thin diffusion barrier layer as in the electroplating method. In addition, in the case of the SPS process, there is a disadvantage in that it is not easy to control the thickness. That is, to control the thickness, the heat treatment temperature must be controlled along with the pressure control. If more pressure is applied to reduce the thickness, cracks or fractures may occur in the specimen, and if more temperature is applied, the desired phase may not come out. There are disadvantages. Conversely, if less pressure is applied, a void may be formed between the electrode and the substrate, and if the temperature is reduced, a desired phase may not be obtained or sintering may not be performed properly.

In addition, in the method of manufacturing a thermoelectric device of the present invention, a small amount of material can be used because the diffusion barrier layer is formed using electroplating, and since a precursor of the first material and the second material is used, even if a material with low purity is used There is no influence on the characteristics of the thermoelectric element. In the case of a precursor used in electroplating, even if the purity of the metal salt or metal oxide is low, in reality, only the desired metallic material is deposited on the substrate at the optimized potential during the plating process. Even after that, it does not affect the electrode characteristics. Furthermore, since the amount of electrode material used for synthesizing the electrode is considerably smaller than that of the SPS process when electroplating is used, there is a significant advantage in terms of cost.

The method for manufacturing the diffusion barrier layer described in the present invention will be described in more detail through examples of the present invention.

[실시예][Example]

A 10 μm Te plating layer was formed on the thermoelectric material part of PbTe by electroplating under the following conditions.

- TeO ₂ : 10 mM (1.596 g/L)

- HNO ₃ : 100 ml/L (70%)

- Applied potential : - 0.1 V

- Agitation : 200 rpm

Then, a 10 μm Ni plating layer was formed on the upper surface of the Te layer by electroplating under the following conditions.

- Ni(SO ₃ NH ₂₎₂ 4H ₂ O : 470 g /L

- Boric acid: 30 g/L

- Applied potential : 5ASD

- Temp. : 50℃

Next, a Ni thin film was formed on the Ni plating layer by electroplating on the exposed upper surface of the thermoelectric material part and on both sides of the Te layer.

After the formation of the electroplating layer was completed, the temperature was raised to 350°C at 10°C/min temperature rising condition, and then a heat treatment process was performed in which the temperature was maintained at 350°C for 1 hour. The heat treatment process was performed in an N ₂ atmosphere.

It can be seen that the diffusion barrier layer including the first layer Ni ₃ Te ₂ and the second layer Ni layer is formed on the thermoelectric material part of the thermoelectric element by the heat treatment.

4A is a graph showing the coefficient of thermal expansion (CTE) of PbTe, and FIG. 4B is a graph showing the coefficient of thermal expansion (CTE) of nickel. The graph in Fig. 4a shows the CTE of bulk materials of PbTe and ZnSe. The dotted line represents the developed value in the simulation. The graph of FIG. 4b shows the CTE of Ni-YSZ in the range of 0 to 1000° C., and in the case of the nickel CTE, about 16 to 17 x 10 ^-6 K ^-1 in the range of 400 to 600° C. 5 is a photograph showing a phenomenon in which a nickel layer is peeled off when a nickel layer is formed as a diffusion barrier layer by an electroplating process and then heat treated.

As shown in Figure 4a, the thermal expansion coefficient of the PbTe is constant from 300K to about 20 x 10 ^-6 K ^-1 . On the other hand, as shown in FIG. 4b, the thermal expansion coefficient of nickel is about 13 x 10 ^-6 K ^-1 at room temperature and about 16-17 x 10 ^-6 K ^-1 at 400 to 600 °C, so the difference in thermal expansion coefficient with PbTe It can be seen that is about 4 x 10 ^-6 K ^-1 . As shown in FIG. 5 , when a Ni layer was formed on a PbTe thermoelectric material using an electroplating process due to the difference in the coefficient of thermal expansion as described above, peeling occurred during heat treatment at a driving temperature (600° C.).

6 is a graph showing X-ray diffraction patterns of a Ni _x Te _y diffusion barrier layer for a medium temperature thermoelectric element formed by an electroplating method according to an embodiment of the present invention. As shown in the graph, it can be confirmed that the diffusion barrier layer including the first layer Ni ₃ Te ₂ and the second layer Ni layer is formed on the thermoelectric material part of the thermoelectric element according to the present invention.

7 is a photograph showing the results of an adhesion test of a Ni _x Te _y diffusion barrier layer for a medium temperature thermoelectric device formed by an electroplating method according to an embodiment of the present invention. As shown in the photo, it can be seen that the thermoelectric material part and the diffusion prevention layer of the thermoelectric element according to the present invention have excellent bonding strength.

The diffusion barrier layer described in the present invention is to produce an interfacial diffusion prevention IMC for a medium temperature thermoelectric material. More specifically, tellurium and nickel layers are sequentially deposited at room temperature by an electrodeposition method, and a low temperature heat treatment process ( 350℃) to form an IMC (Ni _x Te _y ) phase between Ni and Te. When the method proposed in the present invention is used, the diffusion barrier layer can be manufactured at low cost and mass-produced in a large area. There is a big advantage that In the case of the diffusion barrier layer synthesized in this way, it was confirmed that peel-off from the thermoelectric material did not occur when heat treatment was performed at 600° C., which is the driving temperature of the thermoelectric element for medium temperature.

If the coefficient of thermal expansion (CTE) of the diffusion barrier layer deposited on the medium temperature thermoelectric material is different from that of the thermoelectric material, there is a high possibility of peeling or cracking at the device operating temperature (500~600℃). However, in the present invention, a stable metallization layer (Ni/Ni ₃ Te ₂ ) was formed in a simple way by depositing Te with a thermal expansion coefficient almost similar to that of PbTe using electroplating first, then plating a Ni layer thereon and heat-treating it at low temperature. , the formed metallization layer did not peel or crack even at the thermoelectric element driving temperature.

In the case of the diffusion barrier layer and its manufacturing method described in the present invention, it is a technology for synthesizing a diffusion barrier layer for a medium temperature thermoelectric material based on plating for the first time.

Although the present disclosure has been described in detail through specific examples, this is for the purpose of describing the present disclosure in detail, and the present disclosure is not limited thereto, and by those of ordinary skill in the art within the technical spirit of the present disclosure It is clear that the modification or improvement is possible. All simple modifications and variations of the present disclosure fall within the scope of the present disclosure, and the specific protection scope of the present disclosure will be made clear by the appended claims.

[Explanation of code]

100: substrate part

110: ceramic substrate

120: electrode

130: blazing filler

200: thermoelectric material part

300: diffusion barrier layer

310: first material plating layer

320: second material plating layer

320': second material thin film

322: second floor

330: first floor

Claims

first material;

second material; and

A bonding layer and a diffusion prevention structure between the first material and the second material;

The bonding layer and the diffusion preventing structure may include: a first layer made of an intermetallic compound of the first material and the second material and in contact with the second material; and a second layer made of a material forming an intermetallic compound with the first material and formed on the first layer.
substrate part;

thermoelectric material unit; and

a diffusion barrier layer formed between the substrate unit and the thermoelectric material unit;

The diffusion barrier layer may include: a first layer made of an intermetallic compound of a first material and a second material and in contact with the thermoelectric material part; and a second layer formed of the first material and a second material forming an intermetallic compound and formed on the first layer.
3. The method of claim 2,

The difference between the thermal expansion coefficient of the material constituting the thermoelectric material and the thermal expansion coefficient of the first material is 5 x 10 -6 K -1 or less, a medium temperature thermoelectric element.
3. The method of claim 2,

The material constituting the thermoelectric material part is PbTe,

The first material is Te, and the second material is Ni, a medium temperature thermoelectric device.
3. The method of claim 2,

The material constituting the thermoelectric material part is PbTe,

The first material is Sn, and the second material is Cu.
3. The method of claim 2,

The material constituting the thermoelectric material part is PbTe,

The first material is Co, and the second material is Fe, a medium temperature thermoelectric device.
3. The method of claim 2,

The diffusion barrier layer has a thickness of 0.5 to 10 μm, a medium temperature thermoelectric device.
3. The method of claim 2,

The intermetallic compound of the first layer is formed by heat treatment after plating a second material on the plating layer of the first material formed on the substrate portion, a medium temperature thermoelectric device.
9. The method of claim 8,

The material constituting the thermoelectric material part is prevented from being diffused into the diffusion prevention layer by the first material plating layer, and the thermoelectric material part is more uniform than when the diffusion prevention layer formed by the spark plasma sintering (SPS) process is formed. A medium temperature thermoelectric element having a composition.
3. The method of claim 2,

The second layer is formed on the upper surface and both sides of the first layer, a medium temperature thermoelectric element.
i) preparing a thermoelectric material part of a medium temperature thermoelectric element; and

ii) forming a diffusion barrier layer formed of a first layer and a second layer on the thermoelectric material part; and

Step ii) is

ii-1) forming a first material plating layer by electroplating a first material on the thermoelectric material part;

ii-2) forming a second material plating layer by electroplating a second material forming an intermetallic compound with the first material on the first material plating layer; and

ii-3) a first layer comprising an intermetallic compound of a first material and a second material by heat treatment and in contact with the thermoelectric material part; and forming a second layer made of only a second material and formed on the first layer.
12. The method of claim 11,

The difference between the thermal expansion coefficient of the material constituting the thermoelectric material part and the thermal expansion coefficient of the first material is 5 x 10 -6 K -1 or less, a method of manufacturing a medium temperature thermoelectric element.
12. The method of claim 11,

The material constituting the thermoelectric material part is PbTe,

The first material is Te, and the second material is Ni.
12. The method of claim 11,

The material constituting the thermoelectric material part is PbTe,

The first material is Sn, and the second material is Cu.
12. The method of claim 11,

The material constituting the thermoelectric material part is PbTe,

The first material is Co, and the second material is Fe.
12. The method of claim 11,

In step ii), the material constituting the thermoelectric material part is prevented from being diffused into the diffusion barrier layer by the plating layer of the first material, and the thermoelectric material part is formed by a spark plasma sintering (SPS) process. A method for manufacturing a medium temperature thermoelectric element having a uniform composition.
12. The method of claim 11,

In ii-2) above

electroplating a second material on an upper surface of the first material plating layer; and

and electroplating a second material such that the second layer is formed on the upper surface and both sides of the first layer.