阅读说明：本技术 一种带应力驰豫的dbc陶瓷基板、热电器件及其制备方法 (DBC (dielectric Barrier ceramic) ceramic substrate with stress relaxation, thermoelectric device and preparation method of DBC ceramic substrate ) 是由 刘宏 章于道 徐岭 成伟 葛芳萍 于 2020-12-28 设计创作，主要内容包括：本发明公开了一种带应力驰豫的DBC陶瓷基板、热电器件及其制备方法,DBC陶瓷基板包括直接键合铜基板、多壁碳纳米管和铜膜,所述直接键合铜基板包括铜条和陶瓷板,所述铜条固定在所述陶瓷板上,所述铜条表面设有多个孔洞,所述孔洞包括亚微米孔洞和/或纳米孔洞,所述多壁碳纳米管印刷在所述铜条表面上,形成多壁碳纳米管层,所述铜膜镀在所述多壁碳纳米管层上。本发明提供的DBC陶瓷基板、热电器件及其制备方法能够大大驰豫温度变化及分布所产生的热应力,提高了热电的发电效率和温度适应能力,延长了热电器件使用寿命。(The invention discloses a DBC ceramic substrate with stress relaxation, a thermoelectric device and a preparation method thereof, wherein the DBC ceramic substrate comprises a directly-bonded copper substrate, a multi-walled carbon nanotube and a copper film, the directly-bonded copper substrate comprises a copper bar and a ceramic plate, the copper bar is fixed on the ceramic plate, the surface of the copper bar is provided with a plurality of holes, the holes comprise submicron holes and/or nanometer holes, the multi-walled carbon nanotube is printed on the surface of the copper bar to form a multi-walled carbon nanotube layer, and the copper film is plated on the multi-walled carbon nanotube layer. The DBC ceramic substrate, the thermoelectric device and the preparation method thereof can greatly relax thermal stress generated by temperature change and distribution, improve the thermoelectric power generation efficiency and the temperature adaptability and prolong the service life of the thermoelectric device.)

1. The utility model provides a take stress relaxation's DBC ceramic substrate, its characterized in that, includes direct bonding copper base plate, multi-walled carbon nanotube and copper film (4), direct bonding copper base plate includes copper bar (2) and ceramic plate (1), copper bar (2) are fixed on ceramic plate (1), copper bar (2) surface is equipped with a plurality of holes, the hole includes submicron hole and/or nanometer hole, the printing of multi-walled carbon nanotube copper bar (2) are on the surface, form multi-walled carbon nanotube layer (3), copper film (4) are plated on multi-walled carbon nanotube layer (3).

2. The stress-relaxed DBC ceramic substrate according to claim 1, wherein the bonding strength of the multi-walled carbon nanotube layer (3) to the copper bar (2) is greater than or equal to 30 MPa.

3. The stress-relaxed DBC ceramic substrate according to claim 1, wherein the thermal conductivity of the multi-walled carbon nanotube layer (3) in a direction perpendicular to the surface of the ceramic plate (1) is greater than or equal to 800W/(m-K), and the electrical conductivity in a direction parallel to the surface of the ceramic plate (1) is greater than or equal to 10S/cm.

4. The stress-relaxed DBC ceramic substrate of claim 3, wherein the combination of the multi-walled carbon nanotube layer (3) and the copper bars (2) has an overall thermal conductivity of 350W/(m-K) or more in a direction perpendicular to the surface of the ceramic plate (1) and an electrical conductivity of 5.98 x 10 or more in a direction parallel to the surface of the ceramic plate (1)⁵S/cm。

5. The stress-relaxed DBC ceramic substrate according to claim 1, wherein the thickness of the copper film (4) ranges from 20 μ ι η to 30 μ ι η, and the bonding strength of the copper film (4) to the multi-walled carbon nanotube layer (3) is greater than or equal to 45 MPa.

6. The stress-relaxed DBC ceramic substrate according to claim 1, wherein the pores are of a honeycomb structure.

7. A stress-relaxed thermoelectric device comprising the stress-relaxed DBC ceramic substrate of any of claims 1-6.

8. A preparation method of a DBC ceramic substrate with stress relaxation is characterized by comprising the following steps:

s1, placing the directly bonded copper substrate in an organic acid solution for microetching to form submicron holes and/or nanometer holes;

s2, cleaning and drying the directly bonded copper substrate, and then performing a T treatment process to further form nano holes on the copper strip of the directly bonded copper substrate;

s3, printing the multi-wall carbon nanotube sol on a copper strip of the directly bonded copper substrate through screen printing, and forming a multi-wall carbon nanotube layer on the copper strip through natural aging and curing;

s4, placing the directly bonded copper substrate containing the multi-wall carbon nanotube layer in the S3 in a bonding furnace for bonding treatment so as to strengthen the bonding force between the multi-wall carbon nanotube layer and the copper bar;

and S5, correspondingly covering the directly-bonded copper substrate subjected to bonding treatment in the S4 and a metal mask plate, placing the directly-bonded copper substrate and the metal mask plate in an electron beam evaporation system for evaporation coating, and depositing a layer of copper film on the surface of the multi-walled carbon nano tube layer.

9. The method of claim 8, wherein the multi-walled carbon nanotube sol is conditioned with a conductive carbon gel, and the organic acid solution has a PH of 5.0 or more.

10. The method of preparing a stress-relaxed DBC ceramic substrate according to claim 8, wherein the bonding process is performed in a vacuum isothermal and isobaric environment.

Technical Field

The invention relates to the technical field of semiconductor thermoelectric materials, in particular to a DBC (direct bonded copper) ceramic substrate with stress relaxation, a thermoelectric device and a preparation method thereof.

Background

The demand for developing a new energy supply strategy has increased dramatically, stimulating the interest of countries in new renewable energy technologies. Thermoelectric technology is capable of directly converting waste heat into electrical energy without the need for maintenance, and has become a rapidly developing hotspot of sustainable energy harvesting technology. In recent years, the continuous emission of industrial waste heat causes global climate deterioration and fossil fuel waste, and the TE conversion technology can be used for successfully and effectively collecting and converting waste gas and waste heat emitted in the industrial production process into electric energy, so that an energy collection and conversion mode which can be used as energy conservation and emission reduction is disclosed. Inorganic TE materials widely used at present, e.g. Bi₂Te₃PbTe, SnSe, etc., have shown the best TE performance in their respective operating temperature ranges. However, their application scenarios are still severely limited by the inherent bonding characteristics that determine their inherent rigidity and brittleness. In recent years, organic TE materials have been rapidly developed with their unique advantages of flexibility, light weight, easy processing, etc. However, practical applications are still greatly limited due to low efficiency, high contact resistance with metal electrodes, difficult processing of n-type electrodes, poor air/thermal stability, narrow operating temperature range, corrosion problems, and the like. Therefore, it remains a great challenge to fabricate high-performance TEG device systems with thermal stress relaxation. Finding an effective way to improve the thermal stress relaxation capability of inorganic TE material devices has been a research hotspot in various subject fields. One method is to prepare porous inorganic materials on flexible organic substrates using solution and drop casting methods. The porous structure is able to accommodate deformation, thereby providing an important contribution to flexibility. For example, Sun et al prepared a Room Temperature (RT) ZT value of 7X 10^-3The flexible paper-based nanocomposite of (a); dun et al prepared flexible self-assembled Te nanorods on polyvinylidene fluoride substrates with a Power Factor (PF) of 45.8 μ W/m.K at room temperature²(ii) a Lu et al synthesized Bi on polyimide₂Te₃The maximum PF of the thin film TE device based on nano particles is 180 mu W/m.K at 523K². In addition, the nano microporous structure is found to be capable of effectively dispersing phonons, reducing the thermal conductivity and improving the Seebeck coefficient. However, their conductive properties are severely deteriorated compared to bulk materials, which may be due to contamination, poor interconnection lines, severe carrier scattering, etc. Therefore, it is very important to develop a suitable DBC ceramic substrate with stress relaxation.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a DBC ceramic substrate with stress relaxation, a thermoelectric device and a preparation method thereof, wherein the technical scheme is as follows:

in one aspect, the invention provides a DBC ceramic substrate with stress relaxation, which comprises a directly bonded copper substrate, a multiwalled carbon nanotube and a copper film, wherein the directly bonded copper substrate comprises a copper bar and a ceramic plate, the copper bar is fixed on the ceramic plate, a plurality of holes are formed in the surface of the copper bar, the holes comprise submicron holes and/or nanometer holes, the multiwalled carbon nanotube is printed on the surface of the copper bar to form a multiwalled carbon nanotube layer, and the copper film is plated on the multiwalled carbon nanotube layer.

Further, the bonding strength of the multi-wall carbon nanotube layer and the copper bar is greater than or equal to 30 MPa.

Further, the thermal conductivity of the multi-wall carbon nanotube layer in a direction perpendicular to the surface of the ceramic plate is greater than or equal to 800W/(m.K), and the electrical conductivity in a direction parallel to the surface of the ceramic plate is greater than or equal to 10S/cm.

Further, the integral thermal conductivity of the combination of the multi-wall carbon nanotube layer and the copper strip in the direction vertical to the surface of the ceramic plate is greater than or equal to 350W/(m.K), and the electrical conductivity in the direction parallel to the surface of the ceramic plate is greater than or equal to 5.98 x 10⁵S/cm。

Further, the thickness of the copper film ranges from 20 μm to 30 μm.

Further, the bonding strength of the copper film and the multi-wall carbon nanotube layer is greater than or equal to 45 MPa.

Further, the holes are of a honeycomb structure.

In another aspect, the present invention provides a stress-relaxed thermoelectric device comprising said stress-relaxed DBC ceramic substrate.

In still another aspect, the present invention provides a method for preparing a DBC ceramic substrate with stress relaxation, comprising the steps of:

s1, placing the directly bonded copper substrate in an organic acid solution for microetching to form submicron holes and/or nanometer holes;

s2, cleaning and drying the directly bonded copper substrate, and then performing a T treatment process to further form nano holes on the copper strip of the directly bonded copper substrate;

s3, printing the multi-wall carbon nanotube sol on a copper strip of the directly bonded copper substrate through screen printing, and forming a multi-wall carbon nanotube layer on the copper strip through natural aging and curing;

s4, placing the directly bonded copper substrate containing the multi-wall carbon nanotube layer in the S3 in a bonding furnace for bonding treatment so as to strengthen the bonding force between the multi-wall carbon nanotube layer and the copper bar;

and S5, correspondingly covering the directly-bonded copper substrate subjected to bonding treatment in the S4 and a metal mask plate, placing the directly-bonded copper substrate and the metal mask plate in an electron beam evaporation system for evaporation coating, and depositing a layer of copper film on the surface of the multi-walled carbon nano tube layer.

Further, the multi-walled carbon nanotube sol is prepared by using a conductive carbon adhesive, and the pH value of the organic acid solution is greater than or equal to 5.0.

Further, the bonding process is performed in a vacuum isothermal and isobaric environment.

The technical scheme provided by the invention has the following beneficial effects:

a. normal operation can be carried out within a larger temperature variation range;

b. the material has stress relaxation performance, can still normally work in a millimeter wave working environment, and is not easy to crack;

c. the power generation efficiency and the temperature adaptability of the thermoelectric device are improved, and the service life of the thermoelectric device is prolonged.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic plan view of a DBC ceramic substrate with stress relaxation provided by an embodiment of the present invention;

fig. 2 is a schematic cross-sectional view of a DBC ceramic substrate with stress relaxation according to an embodiment of the present invention;

fig. 3 is a schematic flow chart of a method for manufacturing a DBC ceramic substrate with stress relaxation according to an embodiment of the present invention.

Wherein the reference numerals include: 1-ceramic plate, 2-copper bar, 3-multi-wall carbon nanotube layer and 4-copper film.

Detailed Description

In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, apparatus, article, or device that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or device.

In an embodiment of the present invention, a DBC ceramic substrate with stress relaxation is provided, referring to fig. 1 and fig. 2, including a directly bonded copper substrate, a multi-walled carbon nanotube and a copper film 4, the directly bonded copper substrate includes a copper bar 2 and a ceramic plate 1, the copper bar 2 is fixed on the ceramic plate 1, a surface of the copper bar 2 is provided with a plurality of holes, the holes include submicron holes and/or nano holes, the holes are in a honeycomb structure, the multi-walled carbon nanotube is printed on the surface of the copper bar 2 to form a multi-walled carbon nanotube layer 3, the copper film 4 is plated on the multi-walled carbon nanotube layer 3, the thickness of the copper film 4 ranges from 20 μm to 30 μm, preferably 25 μm, and the bonding strength of the copper film 4 and the multi-walled carbon nanotube layer 3 is greater than or equal to 45 MPa. It should be noted that in this embodiment, the copper bar and the copper film may be replaced by other metals with similar functions, and the solution of implementing the same function by simply replacing the copper bar or the copper film with the metal is still within the protection scope of this embodiment.

Wherein the bonding strength of the multi-wall carbon nanotube layer 3 and the copper bar 2 is greater than or equal to 30MPa, the thermal conductivity of the multi-wall carbon nanotube layer 3 in the direction perpendicular to the surface of the ceramic plate 1 is greater than or equal to 800W/(m.K), and the electrical conductivity in the direction parallel to the surface of the ceramic plate 1 is greater than or equal to 10S/cm; the integral thermal conductivity of the combination of the multi-wall carbon nanotube layer 3 and the copper bar 2 in the direction vertical to the surface of the ceramic plate 1 is greater than or equal to 350W/(m.K), and the electrical conductivity in the direction parallel to the surface of the ceramic plate 1 is greater than or equal to 5.98 x 10⁵S/cm. It should be noted that the surface of the ceramic plate 1 mentioned herein refers to the plane where the copper bar 2 contacts the ceramic plate 1, the plane is also parallel to the upper surface of the copper bar 2, the upper surface of the copper bar 2 contacts the multi-walled carbon nanotube, see fig. 2, and the D with stress relaxationThe BC ceramic substrate is sequentially provided with a copper film 4, a multi-wall carbon nanotube layer 3, a copper bar 2 and a ceramic plate 1 from top to bottom.

In an embodiment of the present invention, a thermoelectric device with stress relaxation is further provided, including the DBC ceramic substrate with stress relaxation, and the adoption of the DBC ceramic substrate with stress relaxation enables the thermoelectric device to greatly relax temperature variation and distribute generated thermal stress, thereby improving thermoelectric power generation efficiency and temperature adaptability, being applicable to higher temperature heat recovery power generation, and prolonging the service life of the thermoelectric device.

In an embodiment of the present invention, there is also provided a method for preparing a DBC ceramic substrate with stress relaxation, referring to fig. 3, including the steps of:

s1, placing the directly bonded copper substrate in an organic acid solution for microetching to form submicron holes and/or nanometer holes, wherein the pH value of the used organic acid solution is greater than or equal to 5.0;

s2, cleaning and drying the directly bonded copper substrate, and then performing a T treatment process to further form nano holes on the copper strip of the directly bonded copper substrate;

s3, printing the multi-walled carbon nanotube sol prepared by the conductive carbon adhesive on the copper bar of the directly bonded copper substrate through screen printing, and forming a multi-walled carbon nanotube layer on the copper bar through natural aging and curing;

s4, placing the directly bonded copper substrate containing the multi-wall carbon nanotube layer in the S3 in a bonding furnace for vacuum isothermal isobaric bonding treatment to strengthen the bonding force between the multi-wall carbon nanotube layer and the copper bar, so that the bonding strength between the multi-wall carbon nanotube layer and the copper bar is greater than or equal to 30 MPa;

s5, correspondingly covering the directly-bonded copper substrate subjected to bonding treatment in the S4 and a metal mask plate, placing the directly-bonded copper substrate and the metal mask plate into an electron beam evaporation system for evaporation coating, and depositing a copper film on the surface of the multi-walled carbon nano tube layer, wherein the thickness range of the deposited copper film is 20-30 mu m, and the bonding strength of the copper film and the multi-walled carbon nano tube layer is greater than or equal to 45 MPa.

It should be noted that the nanopores further generated on the copper bar under the T treatment process in step S2 have a honeycomb structure and are smaller than the pores generated on the copper bar in step S1, so as to facilitate the printing and attaching of the multi-wall carbon nanotube sol.

The DBC ceramic substrate with stress relaxation and the thermoelectric device provided by the invention overcome the problem of thermoelectric conversion of relatively high-temperature waste heat of the traditional semiconductor thermoelectric device, and through limited experiments, the TEG thermoelectric device prepared by adopting the DBC ceramic substrate can continuously work at-20 ℃ to +200 ℃, the work failure rate is not more than 0.02%, and the probability of crack occurrence of the ceramic substrate in a millimeter wave working environment is not more than 1%.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.