CN114956850A

CN114956850A - Method for preparing copper-clad nitride ceramic plate by using metal wire nano film

Info

Publication number: CN114956850A
Application number: CN202210389666.5A
Authority: CN
Inventors: 朱焰焰; 李德善; 李华杨
Original assignee: TIANNUO PHOTOELECTRIC MATERIAL CO Ltd
Current assignee: TIANNUO PHOTOELECTRIC MATERIAL CO Ltd
Priority date: 2022-04-14
Filing date: 2022-04-14
Publication date: 2022-08-30
Anticipated expiration: 2042-04-14
Also published as: CN114956850B

Abstract

The invention belongs to the technical field of ceramic materials, and particularly relates to a method for preparing a copper-clad nitride ceramic plate by using a metal wire nano film. The method comprises the following steps: dispersing the metal nanowires in a solvent to obtain a metal nanowire solution; vacuum filtering the metal nanowire solution by adopting a mixed cellulose filter membrane; depositing a layer of metal nanowire film on the mixed cellulose filter membrane after filtering, attaching the metal nanowire film to a copper plate, drying the copper plate under vacuum, and separating the mixed cellulose filter membrane to obtain the copper plate attached with the metal nanowire film; after a layer of active metal film is coated on the nitride ceramic substrate, the copper plate with the metal nanowire film is attached to the nitride ceramic substrate, and hot pressing treatment is carried out. The method of the invention has small damage to the ceramic substrate and small residual stress after brazing, and can reduce the porosity and improve the binding force of the copper plate and the nitride ceramic substrate.

Description

Method for preparing copper-clad nitride ceramic plate by using metal wire nano film

Technical Field

The invention belongs to the technical field of ceramic materials, and particularly relates to a method for preparing a copper-clad nitride ceramic plate by using a metal wire nano film.

Background

The technology of oxide ceramics manufacture has made a very important advance in the last century, and the products thereof have been widely used and have enjoyed brilliant results in the civil and military fields of the electronics industry and other industrial sectors. However, with the rapid development of high and new technologies, the performance of oxide ceramics can not meet the requirements of the continuous development of some high-end key devices, so that nitrides have extremely superior performance in this century: high thermal conductivity, low dielectric constant, low dielectric loss, excellent electrical insulation, thermal expansion coefficient matched with silicon, nontoxicity and the like, so that the material becomes an ideal material for high-density, high-power and high-speed integrated circuit boards and packaging substrates. The global multidisciplinary and multi-industry demands for high attention and wide range are triggered, and especially the large-scale brilliance is brought to the field of high-power charging modules.

The nitride ceramic copper-clad technology starts in the nineties of the last century, is mainly used for IGBT core elements, and is successfully applied to the fields of high-power LED packaging, high-power charging, semiconductors and the like of high-speed rails, electric new energy automobiles, wind power generation, smart grids and the like.

At present, nitride ceramic circuit boards are divided into thin film type and thick film type, and the preparation methods are more, including DBC process, AMB process and the current advanced LAM laser rapid activation metallization process, but the mainstream preparation process still mainly uses AMB active metal brazing.

The brazing mode of the nitride ceramic circuit board AMB process mainly uses brazing paste (screen printing and coating), metal sheet superposition, alloy brazing sheets and the like to braze copper materials, meanwhile, organic solvents contained in the brazing paste can cause air holes and incomplete volatilization, even decomposition products of the air holes and the volatilization directly influence the overall quality of the circuit board, and the yield is low. The lamination of metal sheets and their alloy brazing sheets avoid the use of organic solvent, but are limited by the problems of process technology, and the brazing foil has generally large thickness (different from 50 μm to 80 μm) and high price. Meanwhile, since the sheet and the solder paste are generally made of rolled sheet of metal and atomized powder of metal, the melting point is high and close to the melting point of the metal itself, and soldering needs to be performed at a high temperature (800 ℃ to 1000 ℃) to form eutectic and molten state, and the damage to the base material is generally large and the residual stress after soldering is large.

Disclosure of Invention

The invention mainly aims to provide a method for preparing a copper-clad nitride ceramic plate by utilizing a metal wire nano film, which has small damage to a ceramic substrate and small residual stress after brazing, and can effectively reduce the porosity and improve the bonding force between a copper plate and a nitride ceramic substrate.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a method for preparing a copper-clad nitride ceramic plate by using a metal wire nano film, which comprises the following steps:

dispersing the metal nanowires in a solvent to obtain a metal nanowire solution; vacuum filtering the metal nanowire solution by adopting a mixed cellulose filter membrane; depositing a layer of metal nanowire film on the mixed cellulose filter membrane after filtering, attaching the metal nanowire film to a copper plate, drying the copper plate under vacuum, and separating the mixed cellulose filter membrane to obtain the copper plate attached with the metal nanowire film;

after a layer of active metal film is coated on the nitride ceramic substrate, the copper plate with the metal nanowire film is attached to the nitride ceramic substrate, and hot pressing treatment is carried out.

Physical vapor deposition may be used to deposit a film of active metal on the nitride ceramic substrate, but is not limited to this method, and other conventional methods may be used to plate the active metal on the nitride ceramic substrate.

The metal nanowires are further cleaned before being dispersed in the solvent.

Further, the diameter of the metal nanowire is 20nm-800nm, and the length of the metal nanowire is 10 μm-300 μm; the concentration of the obtained metal nanowire solution is 0.1-20 mg/mL.

Further, the metal nanowire is one or more of an Ag nanowire, an Au nanowire, a Cu nanowire, a Ni nanowire, an Ag-Cu nanowire and an Ag-Ni nanowire.

Further, the solvent is one or more of water, ethanol, isopropanol, cyclohexane, N-hexane, N-dimethylformamide and terpineol.

Furthermore, the aperture size of the mixed cellulose filter membrane is 0.15-0.45 μm.

Further, the mixed cellulose filter membrane deposited with a layer of metal nanowire film is attached to a copper plate for 5min to 15min under the pressure of 2MPa to 20 MPa.

Furthermore, the roughness of the nitride ceramic substrate is 0.1-1.5 μm, and the thickness of the active metal film is 2-10 μm. The active metal is one or more of Zr, Ti, V, Hf and Cr. The nitride ceramic substrate includes, but is not limited to, an aluminum nitride ceramic substrate, a silicon nitride ceramic substrate. Meanwhile, the roughness of the nitride ceramic substrate is between 0.1 and 1.5 mu m, so that the serious loss of the mechanical property of the ceramic plate caused by excessive coarsening can be effectively avoided, and the excessively smooth surface is not beneficial to the reaction of a brazing layer and the ceramic plate and influences the brazing strength. And the thickness of the active metal film is 2-10um, so that not only can the waste of the brazing filler metal be effectively avoided, but also an enough reaction interface can be provided, and meanwhile, the subsequent etching is convenient.

Further, the hot-pressing pressure is 0.001-10MPa, the hot-pressing temperature is 300-600 ℃, and the hot-pressing time is 2-6 h.

The principle of the method is that the metal nanowires are uniformly dispersed in a solvent, and the uniformly dispersed metal nanowire solution is subjected to vacuum filtration by using the mixed cellulose filter membrane, so that the metal nanowires are uniformly and randomly deposited on the cellulose filter membrane, and in the process, nanowires of different metals can be mixed, and nano cellulose films with different thicknesses can be deposited through different nanowire contents. And then attaching the cellulose filter membrane on which the metal nanowire film is deposited to the copper surface, attaching the metal nanowire film to the copper surface in a mechanical pressing mode, drying in vacuum, dehydrating and shrinking the dried nanocellulose filter membrane, and separating the nanocellulose filter membrane from the metal nanowire film. And after the surface of the nitride ceramic is subjected to physical vapor deposition of an active metal film, the nitride ceramic is attached to a copper surface with the nanowire film and hot-pressed to obtain the nitride copper-clad plate. In the process, as the nano-wire is in a nano scale, surface atoms are in an unstable state, so that the surface lattice vibration amplitude is large, and the nano-wire has high surface energy, and has huge energy. This makes it possible to make it more active at lower energy input, which is macroscopically manifested by a large reduction in melting point. By utilizing the characteristic, the nanowire metal film of the brazing layer can enter a eutectic and molten state at a low temperature, so that the nitride ceramic, the brazing layer and the copper plate are mutually connected to obtain the nitride ceramic copper clad plate, as shown in figure 1.

Compared with the prior art, the invention has the following advantages:

the method has low brazing temperature, can effectively protect the ceramic base material, and solves the problems of ceramic substrate fracture, joint brittle fracture and the like caused by mismatching of stress between the copper material and the ceramic.

The method can effectively control the problem of incomplete copper layer eutectic caused by uneven coating of the nano silver, thereby reducing the porosity and improving the brazing strength.

The invention can also effectively reduce the problem of loss of the nano-silver on the surface of the titanium layer in the solvent coating nano-silver mode, thereby improving the utilization rate of the nano-silver, increasing the contact area, reducing the waste of the solder and controlling the thickness of the brazing layer.

The invention utilizes the mixed cellulose filter membrane to effectively transfer the metal nanowire film to the surface of the copper material, thereby avoiding the problem of pore sealing caused by the fact that the solvent cannot volatilize due to close attachment in the hot pressing process.

Drawings

FIG. 1 is a schematic view of the process of the present invention;

fig. 2 is a stacked view of the silver nanowires described in example 1.

The material comprises a copper plate 1, a metal nanowire film 2, an active metal film 3 and a nitride ceramic substrate 4.

Detailed Description

It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the invention. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of the stated features, steps, operations, and/or combinations thereof, unless the context clearly indicates otherwise.

In order to make the technical solutions of the present invention more clearly understood by those skilled in the art, the technical solutions of the present invention will be described in detail below with reference to specific embodiments.

The thickness of the copper plate used in each of the following examples was 0.3 mm.

Comparative example 1

Dispersing 500mg of nano silver wires with the diameter of 50nm in ethanol, performing ultrasonic treatment at 80w power for 20min to remove organic matters on the surfaces of the nano silver wires, performing centrifugal separation, performing vacuum drying treatment on the separated nano silver wires at 60 ℃, preparing the dried nano silver wires into a solution of 1mg/ml in water, and performing ultrasonic dispersion for 20 min. And then dispersing the nano silver wires in an organic solvent, coating the nano silver wires on the copper sheet for multiple times in a coating mode, wherein the coating thickness is 500nm, and carrying out vacuum drying after pressing the nano silver wire film under 10MPa so as to separate the nano silver wire film from the mixed cellulose filter membrane.

Taking a silicon nitride ceramic substrate with the roughness Ra of about 0.8 mu m, and carrying out ultrasonic treatment in absolute ethyl alcohol for 20min so as to remove grease and impurities on the surface of the silicon nitride ceramic substrate. Then, the ceramic substrate is subjected to physical vapor deposition of a Ti film, and the thickness of the film layer is about 5 mu m. And finally, laminating the copper plate with the surface of the nano silver wire film and the nitride ceramic deposited with the Ti film, and pressing for 12 hours at the temperature of 600 ℃ and under the pressure of 2MPa by using a high-temperature hot press to obtain the nitride ceramic copper-clad plate.

Example 1

Dispersing 500mg of nano silver wire with the diameter of 50nm in ethanol, removing organic matters on the surface of the nano silver wire by ultrasonic treatment for 20min under the power of 80w, performing centrifugal separation, performing vacuum drying treatment on the separated nano silver wire at the temperature of 60 ℃, preparing the dried nano silver wire into a solution of 1mg/ml in water, and performing ultrasonic dispersion for 20 min. Then, the nano silver wires are vacuum filtered by a copper plate-sized mixed cellulose filter membrane (with the aperture of 0.15 μm), and the nano silver wires will be continuously crossed and overlapped in the deposition process, as shown in fig. 2. Transferring the filtered nano silver wire film and the mixed cellulose filter membrane to the surface of a copper plate together, wherein the thickness of the film layer is 500nm, and carrying out vacuum drying after pressing the nano silver wire film under 10MPa so as to separate the nano silver wire film from the mixed cellulose filter membrane.

Example 2

Dispersing 500mg of nano silver wire with the diameter of 120nm in ethanol, removing organic matters on the surface of the nano silver wire by ultrasonic treatment for 20min under the power of 80w, performing centrifugal separation, performing vacuum drying treatment on the separated nano silver wire at the temperature of 60 ℃, preparing the dried nano silver wire into a solution of 5mg/ml in water, and performing ultrasonic dispersion for 30 min. And then, carrying out vacuum filtration on the nano silver wires by using a mixed cellulose filter membrane (the aperture is 0.45 mu m) with the size of a copper plate, transferring the nano silver wire thin film obtained by filtration and the mixed cellulose filter membrane to the surface of the copper plate together, wherein the thickness of the membrane layer is 1 mu m, and carrying out vacuum drying after carrying out lamination on the nano silver wire thin film for 30min under 15MPa so as to separate the nano silver wire thin film from the mixed cellulose filter membrane.

Taking a silicon nitride ceramic substrate with the roughness Ra of about 0.8 mu m, and carrying out ultrasonic treatment in absolute ethyl alcohol for 20min so as to remove grease and impurities on the surface of the silicon nitride ceramic substrate. Then, the ceramic substrate is subjected to physical vapor deposition of a Ti film, and the thickness of the film layer is about 10 mu m. And finally, adhering the copper plate with the surface of the nano silver wire film to the nitride ceramic with the deposited Ti film, and pressing for 8 hours at the temperature of 450 ℃ by using a high-temperature hot press and under the pressure of 10MPa to obtain the nitride ceramic copper-clad plate.

Example 3

Dispersing 2g of nano Cu wire with the diameter of 100nm in ethanol, performing ultrasonic treatment at 80w power for 20min to remove organic matters on the surface of the nano Cu wire, performing centrifugal separation, performing vacuum drying treatment on the separated nano Cu wire at 60 ℃, preparing the dried nano Cu wire into a solution of 1mg/ml in water, and performing ultrasonic dispersion for 20 min. And then, carrying out vacuum filtration on the nano Cu wires by using a mixed cellulose filter membrane (the aperture is 0.45 mu m) with the size of the copper plate, transferring the nano Cu wire thin film obtained by filtration and the mixed cellulose filter membrane to the surface of the copper plate, pressing the nano Cu wire thin film under 10MPa, and then carrying out vacuum drying to separate the nano Cu wire thin film from the mixed cellulose filter membrane. In the same manner, a silver nanowire film as described in example 2 was applied on the copper nanowire film, and the total thickness of the copper nanowire film and the silver nanowire film was 500nm, thereby forming a three-layer structure of copper sheet-copper nanowire film-silver nanowire film.

Taking a silicon nitride ceramic substrate with the roughness Ra of about 0.6 mu m, and carrying out ultrasonic treatment in absolute ethyl alcohol for 20min so as to remove grease and impurities on the surface of the silicon nitride ceramic substrate. Then, the Ti film is deposited on the ceramic substrate by physical vapor deposition, and the thickness of the film layer is about 10 mu m. And finally, laminating the copper plate with the nano copper wire film on one surface of the nano silver wire double-layer film with the nitride ceramic deposited with the Ti film, and pressing for 4 hours at 550 ℃ and 2MPa by using a high-temperature hot press to obtain the nitride ceramic copper-clad plate.

Example 4

Mixing and dispersing 2g of a 100 nm-diameter nano Cu wire and 500mg of a 50 nm-diameter nano Ag wire in ethanol, ultrasonically treating for 20min at 80w power to remove organic matters on the surface of the mixed nanowire, centrifugally separating, carrying out vacuum drying treatment on the separated nanowire at 100 ℃, preparing the dried nanowire into a 10mg/ml solution in water, and ultrasonically dispersing for 20 min. And then, carrying out vacuum filtration on the mixed nanowire by using a mixed cellulose filter membrane (the aperture is 0.45 mu m) with the size of a copper plate, transferring the nano Cu wire film obtained by filtration and the mixed cellulose filter membrane to the surface of the copper plate together, wherein the thickness of the membrane layer is 1 mu m, and carrying out vacuum drying after carrying out lamination on the nano Cu wire film for 1h under 15MPa so as to separate the mixed nanowire film from the mixed cellulose filter membrane.

Taking a silicon nitride ceramic substrate with the roughness Ra of about 0.6 mu m, and carrying out ultrasonic treatment in absolute ethyl alcohol for 20min so as to remove grease and impurities on the surface of the silicon nitride ceramic substrate. Then, the Ti film is deposited on the ceramic substrate by physical vapor deposition, and the thickness of the film layer is about 5 mu m. And finally, laminating the copper plate with the nano copper wire film on one surface of the nano silver wire double-layer film with the nitride ceramic deposited with the Ti film, and pressing for 4 hours at 500 ℃ and 5MPa by using a high-temperature hot press to obtain the nitride ceramic copper-clad plate.

Example 5

Mixing and dispersing 500mg of nano Cu wire with the diameter of 100nm, 1g of nano Ag wire with the diameter of 80nm and 80mg of Ni nano wire with the diameter of 250nm in ethanol, ultrasonically treating for 20min at 80w power to remove organic matters on the surface of the mixed nano wire and carrying out centrifugal separation, carrying out vacuum drying treatment on the separated nano wire at 100 ℃, preparing the dried nano wire into a solution with the concentration of 20mg/ml in water and carrying out ultrasonic dispersion for 20 min. And then, performing vacuum filtration on the mixed nanowires by using a mixed cellulose filter membrane (the aperture is 0.22 mu m) with the size of a copper plate, transferring the nano Cu wire thin film obtained by filtration and the mixed cellulose filter membrane to the surface of the copper plate together, wherein the thickness of the membrane layer is 1 mu m, pressing the nano Cu wire thin film for 1h under 15MPa, and then performing vacuum drying to separate the mixed nanowire thin film from the mixed cellulose filter membrane, and spraying a layer of tin nanoparticles with the particle size of 50nm on the surface of the separated mixed nanowire thin film.

Taking a silicon nitride ceramic substrate with the roughness Ra of about 0.4 mu m, and carrying out ultrasonic treatment in absolute ethyl alcohol for 20min so as to remove grease and impurities on the surface of the silicon nitride ceramic substrate. Then, the ceramic substrate is subjected to physical vapor deposition of a Ti film, and the thickness of the film layer is about 10 mu m. And finally, laminating the copper plate with the nano copper wire film and the nano silver wire double-layer film on one surface with the silicon nitride ceramic deposited with the Ti film, and pressing for 3 hours at the temperature of 350 ℃ and under the pressure of 8MPa by using a high-temperature hot press to obtain the nitride ceramic copper-clad plate.

Example 6

The difference from example 5 is that the nitride ceramic substrate used was an aluminum nitride ceramic substrate, and the rest was the same as example 5.

In order to better illustrate the advantages of the invention, the peel strength of the nitride ceramic copper clad laminate (copper thickness is 0.3mm) prepared by the above example is correspondingly tested, and it can be illustrated that the metal nanowires can be used for realizing direct hot pressing and brazing at low temperature, and simultaneously, good bonding force can be obtained and the porosity can be effectively reduced. The test results are shown in table 1 below:

TABLE 1

Group of	Peel strength N/mm	Porosity of the alloy
			Comparative example	8.4N	0.81％
Example 1	9.2	0.29％
			Example 2	10.6	0.15％
Example 3	11.7	0.24％
			Example 4	11.9	0.17％
Example 5	13.4	0.12％
			Example 6	12.1	0.14％

As can be seen from the table, the comparison of the comparative examples shows that the embodiment uses the mixed cellulose filter membrane to filter and form the nano silver wire, and then the nano silver wire is applied to the nitride ceramic brazing, so that the bonding force can be effectively improved, and the porosity can be reduced.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

Claims

1. A method for preparing a copper-clad nitride ceramic plate by using a metal wire nano film is characterized by comprising the following steps:

2. The method of claim 1, wherein the metal nanowires are 20nm to 800nm in diameter and 10 μ ι η to 300 μ ι η in length; the concentration of the obtained metal nanowire solution is 0.1-20 mg/mL.

3. The method of claim 1 or 2, wherein the metal nanowires are one or more of Ag nanowires, Au nanowires, Cu nanowires, Ni nanowires, Ag-Cu nanowires, Ag-Ni nanowires.

4. The method according to claim 1, wherein the solvent is one or more of water, ethanol, isopropanol, cyclohexane, N-hexane, N-dimethylformamide, terpineol.

5. The method of claim 1, wherein the mixed cellulose filter membrane has a pore size of 0.15 to 0.45 μm.

6. The method as claimed in claim 1, wherein the mixed cellulose filter membrane on which the metal nanowire thin film is deposited is attached to a copper plate under a pressure of 2 to 20Mpa for 5 to 15 min.

7. The method according to claim 1, wherein the nitride ceramic substrate has a roughness of 0.1-1.5 μm and a thickness of the active metal film of 2-10 μm.

8. The method of claim 1, wherein the hot pressing is performed at a hot pressing pressure of 0.001 to 10MPa, a hot pressing temperature of 300 to 600 ℃, and a hot pressing time of 2 to 6 hours.