Aluminum nitride-based copper clad plate and preparation method thereof

Abstract

The application relates to an aluminum nitride-based copper-clad plate and a preparation method thereof, wherein the preparation method comprises the following steps: firstly, performing surface oxidation and air plasma treatment on an aluminum nitride substrate; secondly, adopting a spin coating method to spin coat an ultraviolet reduction active sol containing nano-oxide particles onto the surface of the ceramic substrate to obtain an intermediate layer with controllable micro-rough morphology, and performing high-temperature sintering on the ceramic substrate obtained after the spin coating to make the intermediate layer and the ceramic substrate form firm combination; finally, performing ultraviolet catalytic chemical reduction deposition of copper to obtain the aluminum nitride-based copper-clad plate. Compared with the prior art, the application does not need to use a noble metal activator, the roughness of the surface copper-clad layer is uniform and controllable, the bonding force between the copper-clad layer and the ceramic substrate is high, and the application has the advantages of simple preparation process, easy operation, low raw material cost and the like.

Description

Technical Field

[0001] This invention belongs to the technical field of copper clad laminate materials, and relates to an aluminum nitride-based copper clad laminate and its preparation method. Background Technology

[0002] With the rapid popularization of the electronic information industry and the continuous upgrading of related electronic technologies, electronic and electrical products are constantly developing towards digitalization, miniaturization, flexibility, multi-functionality, high reliability, and low energy consumption, placing increasingly higher demands on the performance of power electronic devices. High efficiency, high reliability, large-scale integration, high power miniaturization, and ultra-high frequency low loss are the main directions for future development.

[0003] For high-power electronic devices, ideal electronic packaging materials must meet the requirements of low expansion, high thermal conductivity, low dielectric constant, and heat and pressure resistance. Currently, commonly used electronic packaging substrate materials fall into three main categories: organic packaging substrate materials, metal substrate materials, and ceramic packaging substrate materials. Compared with the above three, ceramic-based materials have significant advantages in overall performance. They are resistant to high temperatures and humidity, have high mechanical strength, and are not prone to cracking. They also have high thermal conductivity, low dielectric constant, excellent high-frequency characteristics, and low dielectric loss. Due to these advantages, ceramic-based packaging materials are gradually replacing traditional packaging substrates. They are widely used in the packaging of products requiring high temperature, high frequency, and high hermeticity, such as LDs (laser diodes), high-power LEDs (light-emitting diodes), and CPVs (concentrated photovoltaics).

[0004] Currently, commonly used ceramic materials include SiC, Al2O3, BeO, and AlN. In comparison, SiC has an excessively high dielectric constant, limiting its application in high-frequency and high-speed fields. Al2O3 has low thermal conductivity, and its coefficient of linear expansion does not match that of Si. BeO itself is toxic. Therefore, AlN, with its low dielectric constant, high thermal conductivity, and coefficient of thermal expansion matching that of Si, has become a third-generation semiconductor material.

[0005] Despite the numerous advantages of aluminum nitride itself, bonding it with copper presents challenges. Traditional methods employ hot pressing, thin-film or thick-film methods, or noble metal activated copper plating to achieve bonding between aluminum nitride and copper. However, all of these methods suffer from low bonding strength and poor surface roughness. Furthermore, the activators used in the noble metal activated chemical deposition of copper in traditional methods, such as colloidal palladium, are inherently expensive and also cause some environmental pollution.

[0006] This approach, which introduces an intermediate layer with UV catalytic activity and achieves a transition layer between the aluminum nitride substrate and copper through chemical gel sintering, and then uses UV-induced deposition to bond copper to its surface, has not been reported before. Summary of the Invention

[0007] The purpose of this invention is to provide an aluminum nitride copper-clad laminate and its preparation method, which solves the problems of high roughness and low bonding strength between the existing aluminum nitride copper-clad laminate and the copper layer.

[0008] This invention, combining the principle of ultraviolet activation of semiconductor oxides, provides a design scheme for the composition of the intermediate activation layer. The resulting ceramic copper-clad laminate exhibits low surface roughness and high bonding strength between the Cu layer and the substrate, demonstrating significant advantages. The technical solution provided by this invention is applicable to the processing and preparation of copper-clad laminates on non-metallic ceramic substrates such as AlN, SiC, and Si3N4, and also has certain applicability to oxide ceramic substrates.

[0009] The objective of this invention can be achieved through the following technical solutions:

[0010] This invention provides a method for preparing aluminum nitride-based copper clad laminate, the method comprising the following steps:

[0011] 1) The surface of the aluminum nitride substrate is oxidized and then subjected to plasma bombardment to obtain a pretreated surface;

[0012] 2) Prepare an intermediate gel layer by spin-coating the gel onto the surface of an aluminum nitride substrate;

[0013] 3) Dry and sinter the substrate obtained after spin coating;

[0014] 4) The sintered substrate is subjected to ultraviolet-catalyzed chemical deposition of copper to obtain aluminum nitride-based copper clad laminate material.

[0015] Further, in step 1), the method for oxidizing the surface of the aluminum nitride substrate includes: cleaning the aluminum nitride substrate, heating it for oxidation, and then cleaning and drying it. Specifically, the substrate is first cleaned with anhydrous ethanol or anhydrous acetone to remove surface oil, then heated at 1000℃ to 1200℃ for 1 to 2 hours, followed by furnace cooling for 3 to 5 hours; the cooled substrate is then cleaned again with acetone and anhydrous ethanol and dried. The resulting oxide layer thickness is between 500nm and 1μm.

[0016] Furthermore, in step 1), the plasma bombardment time is 1-3 minutes.

[0017] Further, in step 2), the gel preparation method includes: mixing titanium dioxide, silica sol, and ethanol, and then mechanically stirring to obtain a mixed gel with an intermediate gel layer. The mass ratio of titanium dioxide, silica, and ethanol is (1-2):(1-2):5.

[0018] Further, in step 2), the spin coating method includes: dropping the gel onto the surface of the aluminum nitride substrate, spin coating at a speed of 500-600 r / min using a spin coater, and holding for 10-15 seconds.

[0019] Further, in step 3), the sintering method includes: sintering the substrate coated with the intermediate gel layer at 450-550℃ for 1-3 hours, followed by furnace cooling for 1-3 hours, thus obtaining the sintered sample. The preferred sintering parameters are 500℃ and 2 hours. The thickness of the sintered intermediate gel layer is 1-2 μm.

[0020] Further, in step 4), the ultraviolet-catalyzed chemical deposition method includes: irradiating the sintered sample with ultraviolet light, and then placing it in a chemical copper plating solution for chemical copper deposition. The ultraviolet light wavelength is 360-380 nm, the power is 6-10 W, and the irradiation time is 20-30 min. The chemical plating solution contains: 8-10 g / L copper sulfate pentahydrate, 20-22 g / L citric acid, 40-45 g / L sodium hypophosphite, 30-40 g / L boric acid, 0.8-1 g / L nickel sulfate hexahydrate, 20-22 mg / L potassium ferrocyanide, and the final pH is adjusted to 9-10.

[0021] Further, in step 4), the deposition rate is 2-5 μm / h, and the resulting UV-catalyzed copper plating layer is 4-10 μm thick.

[0022] This invention provides an aluminum nitride copper-clad laminate, which is prepared by the method described above. It has low roughness and high bonding strength and can be applied to the field of substrate materials for high-power, high-frequency and high-speed electronic devices.

[0023] The intermediate layer obtained by sintering in this invention not only modifies the roughness of the substrate, reducing the roughness of the deposited copper layer, but also avoids the use of precious metal activation, making it more environmentally friendly, by employing ultraviolet-catalyzed chemical deposition.

[0024] This invention provides a method for preparing a ceramic-based copper-clad laminate, comprising the following steps:

[0025] S1. Plasma treatment is performed on the ceramic substrate;

[0026] S2. Spin-coat the UV-reducing active sol containing nano-oxide particles onto the surface of the ceramic substrate from step S1 to prepare an intermediate layer.

[0027] S3. The substrate obtained after spin coating in step S2 is subjected to air sintering.

[0028] S4. Ultraviolet chemical reduction deposition of copper is performed on the sintered intermediate layer substrate to obtain a ceramic-based copper-clad laminate.

[0029] Further, in step S1, the ceramic substrate includes oxide ceramics and non-oxide ceramics; the non-oxide ceramics include at least one of SiC, AlN, and Si3N4, and the oxide ceramics include at least one of SiO2 and Al2O3.

[0030] Further, in step S1, if the ceramic substrate is a non-oxide ceramic, it needs to undergo air oxidation treatment (i.e., surface oxidation). The air oxidation treatment includes the following steps: the non-oxide ceramic substrate is pre-treated with anhydrous ethanol or anhydrous acetone to remove surface oil, heated to 800℃-1200℃ at a rate of 1-10℃ / min, held for 1-4 hours, and then cooled in the furnace for 4-6 hours. The preferred heating rate, holding temperature, and time are 5℃ / min, 1200℃, and 2 hours, respectively. After cooling, the substrate is cleaned again with acetone and anhydrous ethanol and dried. The thickness of the surface oxide layer obtained on the surface of the ceramic substrate after air oxidation treatment is between 500nm and 1μm.

[0031] Further, in step S1, the plasma treatment method is to use plasma in air to bombard the surface of the ceramic substrate with plasma for 1-10 minutes, preferably 3-5 minutes.

[0032] Furthermore, the UV-reducing active sol used in step S2 includes a titanium dioxide precursor sol with UV-reducing activity; specifically, the titanium dioxide precursor is preferably one or more of titanium acetylacetonate, alcohol-soluble titanium sol, and titanate coupling agent.

[0033] Furthermore, the nano-oxide particles used in step S2 serve to modify the surface morphology roughness; preferably, the nano-oxide particles are nano-silica with a size of 20-100 nm; or organosilanes can be used as the source of nano-silica particles, and silica particles are obtained by hydrolysis of the organosilane after heat treatment. The silane functional groups include, but are not limited to, mercapto, epoxy, and alkoxy groups, and preferably one or more of KH560, KH550, and KH580 organosilicon resins.

[0034] Further, the method for preparing the UV-reducing active sol used in the intermediate layer preparation in step S2 is as follows: titanium dioxide precursor, silica nanoparticles or organosilane are uniformly dispersed in an alcohol solution, wherein the alcohol solution includes at least one of anhydrous ethanol and isopropanol, to obtain a mixed sol; wherein the mass ratio of titanium dioxide precursor: silica nanoparticles or organosilane: anhydrous ethanol is (1-4):(1-4):(5-6).

[0035] Further, the spin coating method in step S2 includes: slowly dripping the sol onto the surface of the ceramic substrate, spin coating at a speed of 200-600 r / min, preferably 400-500 r / min, for a spin coating time of 10-30 s, preferably 15 s.

[0036] Furthermore, the thickness of the intermediate layer obtained in step S2 is between 1 and 2 μm.

[0037] Further, the air sintering method described in step S3 includes: heating from room temperature to 80°C at a rate of 2°C / min, holding at 80°C for 20-30 minutes to remove organic solvents from the sol; heating to 500°C-600°C at a rate of 5°C / min, holding for 1-2 hours, preferably at 550°C for 2 hours, and then cooling with the furnace.

[0038] Further, the ultraviolet reduction chemical deposition method described in step S4 includes: placing the sintered ceramic substrate in a chemical copper plating solution for ultraviolet irradiation to perform chemical copper deposition. Specifically, 200-400 nm wavelength ultraviolet light is selected, preferably 360-380 nm ultraviolet light, and the irradiation time is 20-30 min. The chemical copper deposition solution can be a mature commercial solution or a simpler formulation system, such as a solution containing sodium hypophosphite and formaldehyde as reducing agents. The specific concentrations are as follows: copper sulfate pentahydrate 8-10 g / L, citric acid 20-22 g / L, sodium hypophosphite 40-45 g / L, boric acid 30-40 g / L, nickel sulfate hexahydrate 0.8-1 g / L, potassium ferrocyanide 20-22 mg / L, with the final pH adjusted to 9-10; and copper sulfate pentahydrate 8-10 g / L, citric acid 20-22 g / L, formaldehyde 20-35 g / L, boric acid 30-40 g / L, nickel sulfate hexahydrate 0.8-1 g / L, potassium ferrocyanide 20-22 mg / L, with the final pH adjusted to 10-12.

[0039] Furthermore, the thickness of the copper layer deposited by ultraviolet reduction in step S4 can reach 1-10 μm, or it can be deposited to the required copper layer thickness according to the application requirements.

[0040] This invention provides a ceramic-based copper-clad laminate, which is prepared by the method described above.

[0041] Compared with the prior art, the present invention has the following characteristics:

[0042] 1) This invention prepares aluminum nitride-based copper clad laminates by chemical gel sintering and ultraviolet catalytic deposition of copper, which has the advantages of simple preparation process, easy operation and low raw material cost.

[0043] 2) The aluminum nitride-based copper clad laminate prepared by the present invention has an intermediate layer structure (porous structure). The nanoparticles formed in the intermediate layer have a special three-dimensional interpenetrating network structure, which forms a mechanical lock with copper, which is beneficial to enhance the bonding strength between the substrate and the copper layer.

[0044] 3) The aluminum nitride-based copper clad laminate prepared by the present invention has the ultraviolet catalytic properties of the intermediate layer, which is conducive to achieving ultraviolet catalytic chemical deposition. The catalytic deposition effect is good, and it replaces the activators such as palladium chloride and colloidal palladium used in traditional chemical deposition methods.

[0045] 4) An intermediate layer designed in this invention contains titanium oxide nanoparticles with ultraviolet catalytic activity, which can directly achieve the reduction deposition of metallic copper under ultraviolet light irradiation with a wavelength of 200-400 nanometers to obtain a ceramic-based copper-clad laminate. It has the advantages of simple preparation process, easy operation and low raw material cost.

[0046] 5) The process path of the present invention can be widely applied to a variety of ceramic surfaces, including but not limited to AlN ceramic substrates, and can also be applied to other non-oxide ceramics such as SiC, Si3N4, etc. With appropriate deformation, it can also be applied to other oxide ceramic substrates such as SiO2, Al2O3, etc. Attached Figure Description

[0047] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0048] Figure 1 The image shows the scanning electron microscope (SEM) microstructure of the intermediate layer of the ceramic-based copper-clad laminate prepared in Example 2.

[0049] Figure 2 This is a laser confocal image of the copper layer of the ceramic-based copper-clad laminate prepared in Example 2;

[0050] Figure 3 The image shows the macroscopic morphology of the AlN ceramic-based copper-clad laminate prepared in Example 2.

[0051] Figure 4 This is a cross-sectional view of the microstructure of the intermediate layer of the ceramic-based copper-clad laminate prepared in Example 2 using a scanning electron microscope. Detailed Implementation

[0052] The specific embodiments of the present invention will be described in further detail below with reference to the examples. These examples are used to illustrate the present invention and will help those skilled in the art to further understand the invention, but are not intended to limit the scope of the invention. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0053] Example 1

[0054] A method for preparing aluminum nitride copper-clad laminate includes the following steps:

[0055] 1) The aluminum nitride substrate was ultrasonically cleaned with anhydrous ethanol, then heated to 1100℃ at 5℃ / min, held for 1 hour, cooled in the furnace, and then subjected to plasma bombardment for 30 seconds.

[0056] 2) Titanium sol was selected as the precursor for titanium dioxide, and KH560 silicone resin was selected as the precursor for silica. Both were mixed with ethanol and mechanically stirred for 10 min. The mass fraction ratio of titanium dioxide, silica, and ethanol was 3:2:5. The prepared mixed gel was spin-coated onto a pretreated aluminum nitride substrate in two passes.

[0057] 3) The substrate coated with the intermediate layer is sintered by heating from room temperature to 450°C at a rate of 5°C / min, holding at that temperature for 2 hours, and then cooling to room temperature in the furnace.

[0058] 4) Place the sample to be catalyzed in a petri dish and irradiate it under a 365nm ultraviolet light source for 20 minutes. Then, perform chemical deposition of copper. The chemical deposition solution formula is as follows: 9g / L copper sulfate pentahydrate, 21g / L citric acid, 40g / L sodium hypophosphite, 30g / L boric acid, 1g / L nickel sulfate hexahydrate, and 21mg / L potassium ferrocyanide. The final pH is adjusted to 10. The chemical deposition temperature is 40℃ and the deposition time is 1h. The thickness of the copper coating is 2μm and the bonding strength of the copper coating is 6N / cm.

[0059] Example 2

[0060] A method for preparing aluminum nitride copper-clad laminate includes the following steps:

[0061] 1) The aluminum nitride substrate was ultrasonically cleaned with anhydrous ethanol, then heated to 1100℃ at 5℃ / min, held for 1 hour, cooled in the furnace, and then subjected to plasma bombardment for 30 seconds.

[0062] 2) Titanium sol was selected as the precursor for titanium dioxide, and silica sol was selected as the precursor for silica. Both were mixed with ethanol and mechanically stirred for 10 min. The mass fraction ratio of titanium dioxide, silica, and ethanol was 1:1:6. The prepared mixed gel was spin-coated onto a pretreated aluminum nitride substrate in two passes.

[0063] 3) The substrate coated with the intermediate layer is sintered by heating from room temperature to 450°C at a rate of 5°C / min, holding at that temperature for 2 hours, and then cooling to room temperature in the furnace.

[0064] 4) The sample to be catalyzed was placed in a petri dish and irradiated under a 365nm ultraviolet light source for 25 minutes, followed by chemical deposition of copper. The chemical deposition solution consisted of: 8 g / L copper sulfate pentahydrate, 20 g / L citric acid, 40 g / L sodium hypophosphite, 35 g / L boric acid, 1 g / L nickel sulfate hexahydrate, and 20 mg / L potassium ferrocyanide. The final pH was adjusted to 10. The chemical deposition temperature was 40℃, and the deposition time was 2 hours. The resulting copper coating thickness was 6 μm. The copper coating adhesion strength was 8 N / cm.

[0065] like Figure 1 The image shown is a scanning electron microscope (SEM) image of the intermediate layer of the aluminum nitride copper-clad laminate prepared in this embodiment. Figure 4 This is a cross-sectional image of the scanning electron microscope (SEM) image of the intermediate layer of the aluminum nitride copper-clad laminate prepared in this embodiment. As can be seen from the image, the prepared intermediate layer has a three-dimensional interpenetrating network structure composed of nanoparticles, and the thickness of the intermediate layer is approximately 1-2 micrometers. Figure 2 The image shown is a laser confocal image of the copper layer of the aluminum nitride copper-clad laminate prepared in this embodiment. It can be seen from the image that the copper layer prepared by this method is generally uniform, and the roughness level is between 2μm and 3μm. Figure 3 This indicates that the copper plating layer has a uniform and complete macroscopic morphology, good surface quality, and the typical brick-red color of chemically plated copper layers.

[0066] Example 3

[0067] A method for preparing aluminum nitride copper-clad laminate includes the following steps:

[0068] 1) The aluminum nitride substrate was ultrasonically cleaned with anhydrous ethanol, then heated to 1100℃ at 5℃ / min, held for 1 hour, cooled in the furnace, and then subjected to plasma bombardment for 30 seconds.

[0069] 2) Titanium sol was selected as the precursor for titanium dioxide, and silica sol was selected as the precursor for silica. Both were mixed with ethanol and mechanically stirred for 10 min. The mass fraction ratio of titanium dioxide, silica, and ethanol was 3:2:15. The prepared mixed gel was spin-coated onto a pretreated aluminum nitride substrate in two passes.

[0070] 3) The substrate coated with the intermediate layer is sintered by heating from room temperature to 450°C at a rate of 5°C / min, holding at that temperature for 2 hours, and then cooling to room temperature in the furnace.

[0071] 4) The sample to be catalyzed was placed in a petri dish and irradiated under a 365nm ultraviolet light source for 25 minutes, followed by chemical deposition of copper. The chemical deposition solution consisted of: 9 g / L copper sulfate pentahydrate, 20 g / L citric acid, 40 g / L sodium hypophosphite, 35 g / L boric acid, 1 g / L nickel sulfate hexahydrate, and 20 mg / L potassium ferrocyanide. The final pH was adjusted to 10. The chemical deposition temperature was 40℃, and the deposition time was 2 hours. The resulting copper coating thickness was 6 μm. The copper coating adhesion strength was 7 N / cm.

[0072] Example 4

[0073] A method for preparing aluminum nitride copper-clad laminate includes the following steps:

[0074] 1) The aluminum nitride substrate was ultrasonically cleaned with anhydrous ethanol, then heated to 1100℃ at 5℃ / min, held for 1 hour, cooled in the furnace, and then subjected to plasma bombardment for 30 seconds.

[0075] 2) Titanium acetylacetonate was selected as the precursor for titanium dioxide, and silica sol was selected as the precursor for silica. Both were mixed with ethanol and mechanically stirred for 10 min. The mass fraction ratio of titanium dioxide, silica, and ethanol was 4:1:25. The prepared mixed gel was spin-coated onto a pretreated aluminum nitride substrate in 3 coats.

[0076] 3) The substrate coated with the intermediate layer is sintered by heating from room temperature to 450°C at a rate of 5°C / min, holding at that temperature for 2 hours, and then cooling to room temperature in the furnace.

[0077] 4) The sample to be catalyzed was placed in a petri dish and irradiated under a 365nm ultraviolet light source for 25 minutes, followed by chemical deposition of copper. The chemical deposition solution consisted of: 8 g / L copper sulfate pentahydrate, 20 g / L citric acid, 40 g / L sodium hypophosphite, 35 g / L boric acid, 1 g / L nickel sulfate hexahydrate, and 20 mg / L potassium ferrocyanide. The final pH was adjusted to 9. The chemical deposition temperature was 40℃, and the deposition time was 3 hours. The resulting copper coating thickness was 8 μm. The copper coating adhesion strength was 4 N / cm.

[0078] Example 5

[0079] The preparation of AlN ceramic copper-clad laminate includes the following steps:

[0080] 1) The AlN substrate was ultrasonically cleaned with anhydrous acetone, then heated to 1100℃ at 3℃ / min, held for 1h, cooled in the furnace for 4h, and bombarded with air plasma for 1min.

[0081] 2) Using alcohol-soluble titanium sol as the TiO2 precursor and KH560 organosilicon resin as the SiO2 precursor, the two are miscible with ethanol, maintaining the mass ratio of titanium sol:KH550:ethanol at 3:2:5. The mixture is mechanically stirred for 10 min, and the prepared mixed sol is spin-coated at 300 r / min for 10 s onto the pretreated aluminum nitride substrate. The coating passes are 2 times to obtain the pretreated intermediate layer.

[0082] 3) Sinter the substrate coated with the intermediate layer by heating it to 80°C at a rate of 2°C, holding it at 80°C for 30 minutes to remove the mixed sol solvent; then rapidly heating it to 500°C at a rate of 5°C / min, holding it for 2 hours, and then cooling it in the furnace for 4 hours.

[0083] 4) The substrate was then immersed in a petri dish containing a chemical copper plating solution and irradiated under a 340nm ultraviolet light source for 30 minutes to obtain a copper seed layer. The substrate was then transferred to a beaker for further chemical copper deposition. The chemical copper deposition solution consisted of: 9 g / L copper sulfate pentahydrate, 21 g / L citric acid, 40 g / L sodium hypophosphite, 30 g / L boric acid, 1 g / L nickel sulfate hexahydrate, and 21 mg / L potassium ferrocyanide. The final pH was adjusted to 10. The chemical deposition temperature was 40℃, and the deposition time was 3 hours. The resulting copper plating layer thickness was approximately 8 μm. A 90° peel test showed that the bonding strength between the copper plating layer and the ceramic substrate was 6 N / cm.

[0084] Example 6

[0085] The preparation of AlN ceramic copper-clad laminate includes the following steps:

[0086] 1) The AlN substrate was ultrasonically cleaned with anhydrous acetone, then heated to 1200℃ at 5℃ / min, held for 2h, cooled in the furnace for 4h, and bombarded with air plasma for 3min.

[0087] 2) A titanate coupling agent was selected as the TiO2 precursor, and an alcohol-soluble silica sol was selected as the SiO2 precursor. Both were mixed with ethanol and mechanically stirred for 10 min. The mass ratio of titanate coupling agent, alcohol-soluble silica sol, and ethanol was 3:3:5. The prepared mixed sol was spin-coated at 500 r / min for 20 s onto a pretreated aluminum nitride substrate. Two coating passes were applied to obtain a pretreated intermediate layer.

[0088] 3) Sinter the substrate coated with the intermediate layer by heating it to 80°C at a rate of 2°C, holding it at 80°C for 30 minutes to remove the mixed sol solvent; then heating it to 550°C at a rate of 5°C / min, holding it for 2 hours, and then cooling it in the furnace for 4 hours.

[0089] 4) The substrate was then immersed in a petri dish containing a chemical copper plating solution and irradiated under a 380nm ultraviolet light source for 20 minutes to obtain a copper seed layer. The substrate was then transferred to a beaker for further chemical copper deposition. The chemical deposition solution consisted of: 9 g / L copper sulfate pentahydrate, 21 g / L citric acid, 30 g / L formaldehyde, 30 g / L boric acid, 1 g / L nickel sulfate hexahydrate, and 21 mg / L potassium ferrocyanide. The final pH was adjusted to 12. The chemical deposition temperature was 40℃, and the deposition time was 1 hour. The resulting copper plating layer was approximately 2 μm thick. A 90° peel test showed that the bonding strength between the copper plating layer and the ceramic substrate was 7 N / cm.

[0090] Example 7

[0091] The preparation of AlN ceramic copper-clad laminate includes the following steps:

[0092] 1) The AlN substrate was ultrasonically cleaned with anhydrous acetone, then heated to 1100℃ at 5℃ / min, held for 2h, cooled in the furnace for 4h, and bombarded with air plasma for 5min.

[0093] 2) Titanate coupling agent was selected as the TiO2 precursor, and KH550 was selected as the SiO2 precursor. Both were mixed with ethanol and mechanically stirred for 10 min. The mass fraction ratio of the titanate coupling agent KH550 to ethanol was 1:1:6. The prepared mixed sol was spin-coated at 500 r / min for 15 s onto a pretreated aluminum nitride substrate, with three coating passes, to obtain the pretreated intermediate layer.

[0094] 3) Sinter the substrate coated with the intermediate layer by heating it to 80°C at a rate of 2°C, holding it at 80°C for 30 minutes to remove the mixed sol solvent; then heating it to 550°C at a rate of 5°C / min, holding it for 2 hours, and then cooling it in the furnace for 4 hours.

[0095] 4) The substrate was then immersed in a petri dish containing a chemical copper plating solution and irradiated under a 360nm ultraviolet light source for 30 minutes to obtain a copper seed layer. The substrate was then transferred to a beaker for further chemical copper deposition. The chemical deposition solution consisted of: 8 g / L copper sulfate pentahydrate, 20 g / L citric acid, 40 g / L sodium hypophosphite, 35 g / L boric acid, 1 g / L nickel sulfate hexahydrate, and 20 mg / L potassium ferrocyanide. The final pH was adjusted to 10. The chemical deposition temperature was 40℃, and the deposition time was 2 hours. The resulting copper plating layer thickness was 6 μm. A 90° peel test showed that the bonding strength between the copper plating layer and the ceramic substrate was 8 N / cm.

[0096] Example 8

[0097] The preparation of SiC ceramic copper-clad laminate includes the following steps:

[0098] 1) The SiC substrate was ultrasonically cleaned with anhydrous acetone, then heated to 1200℃ at 5℃ / min, held for 2h, cooled in the furnace for 4h, and bombarded with air plasma for 8min.

[0099] 2) Titanium acetylacetonate was selected as the TiO2 precursor, and alcohol-soluble silica sol was selected as the SiO2 precursor. Both were miscible with isopropanol and mechanically stirred for 10 min. The mass ratio of titanium acetylacetonate, alcohol-soluble silica sol, and isopropanol was 2:3:6. The prepared mixed sol was spin-coated at 600 r / min for 15 s onto a pretreated aluminum nitride substrate, with two coating passes, to obtain a pretreated intermediate layer.

[0100] 3) Sinter the substrate coated with the intermediate layer by heating it to 80°C at a rate of 5°C, holding it at 80°C for 30 minutes to remove the mixed sol solvent; then rapidly heating it to 600°C at a rate of 5°C / min, holding it for 2 hours, and then cooling it in the furnace for 4 hours.

[0101] 4) The substrate was then immersed in a petri dish containing a chemical copper plating solution and irradiated under a 200nm ultraviolet light source for 30 minutes to obtain a copper seed layer. The substrate was then transferred to a beaker for further chemical copper deposition. The chemical deposition solution consisted of: 9 g / L copper sulfate pentahydrate, 20 g / L citric acid, 40 g / L sodium hypophosphite, 35 g / L boric acid, 1 g / L nickel sulfate hexahydrate, and 20 mg / L potassium ferrocyanide. The final pH was adjusted to 10. The chemical deposition temperature was 40℃, and the deposition time was 3 hours. The resulting copper plating layer thickness was 6 μm. A 90° peel test showed that the bonding strength between the copper plating layer and the ceramic substrate was 7 N / cm.

[0102] Example 9

[0103] The preparation of Si3N4 ceramic copper-clad laminate includes the following steps:

[0104] 1) The Si3N4 substrate was ultrasonically cleaned with anhydrous acetone, then heated to 800℃ at 5℃ / min, held for 4h, cooled in the furnace for 4h, and bombarded with air plasma for 10min.

[0105] 2) Titanate coupling agent was selected as the TiO2 precursor, and KH580 was selected as the SiO2 precursor. Both were mixed with ethanol and mechanically stirred for 10 min. The mass fraction ratio of the titanate coupling agent KH580 to ethanol was 4:4:5. The prepared mixed sol was spin-coated at 400 r / min for 30 s onto a pretreated silicon nitride substrate, with three coating passes, to obtain a pretreated intermediate layer.

[0106] 3) Sinter the substrate coated with the intermediate layer by heating it to 80°C at a rate of 5°C, holding it at 80°C for 30 minutes to remove the mixed sol solvent; then rapidly heating it to 550°C at a rate of 5°C / min, holding it for 2 hours, and then cooling it in the furnace for 4 hours.

[0107] 4) The substrate was then immersed in a petri dish containing a chemical copper plating solution and irradiated under a 400nm ultraviolet light source for 25 minutes. Copper was then chemically deposited using a solution formulated as follows: 8 g / L copper sulfate pentahydrate, 20 g / L citric acid, 40 g / L sodium hypophosphite, 35 g / L boric acid, 1 g / L nickel sulfate hexahydrate, and 20 mg / L potassium ferrocyanide. The final pH was adjusted to 9. The chemical deposition temperature was 40℃, and the deposition time was 3 hours. The resulting copper plating thickness was 8 μm. A 90° peel test showed that the bonding strength between the copper plating and the ceramic substrate was 4 N / cm.

[0108] Example 10

[0109] This invention is also applicable to the processing of oxide ceramics, except that the surface oxidation process in step 1) is omitted, and the corresponding ceramic-based copper-clad laminate can still be obtained. The preparation of the SiO2 glass substrate copper-clad laminate in this embodiment includes the following steps:

[0110] 1) The SiO2 substrate was ultrasonically cleaned with anhydrous acetone and bombarded with air plasma for 10 minutes.

[0111] 2) Alcohol-soluble titanium sol was selected as the precursor for TiO2, and alcohol-soluble silica sol was selected as the precursor for SiO2. Both were mixed with ethanol and mechanically stirred for 10 min. The mass fraction ratio of alcohol-soluble titanium sol, alcohol-soluble silica sol, and ethanol was 3:2:5. The prepared mixed sol was spin-coated at 500 r / min for 20 s onto a pretreated silicon nitride substrate, with two coating passes, to obtain a pretreated intermediate layer.

[0112] 3) Sinter the substrate coated with the intermediate layer by heating it to 80°C at a rate of 5°C, holding it at 80°C for 30 minutes to remove the mixed sol solvent; then rapidly heating it to 600°C at a rate of 5°C / min, holding it for 2 hours, and then cooling it in the furnace for 4 hours.

[0113] 4) The substrate was then immersed in a petri dish containing a chemical copper plating solution and irradiated under a 360nm ultraviolet light source for 25 minutes. The chemical deposition solution consisted of: 8 g / L copper sulfate pentahydrate, 20 g / L citric acid, 40 g / L sodium hypophosphite, 35 g / L boric acid, 1 g / L nickel sulfate hexahydrate, and 20 mg / L potassium ferrocyanide. The final pH was adjusted to 9. The chemical deposition temperature was 40℃, and the deposition time was 3 hours. The resulting copper plating layer thickness was 8 μm. A 90° peel test showed that the bonding strength between the copper plating layer and the ceramic substrate was 6 N / cm.

[0114] The key point of this invention lies in constructing a firmly bonded porous intermediate layer on the surface of a ceramic substrate using a sol-gel sintering process. On one hand, this porous intermediate layer achieves effective mechanical bonding with the copper layer, enhancing the bonding strength. On the other hand, the intermediate layer incorporates titanium dioxide, a component with UV reduction catalytic activity, directly achieving the direct reduction deposition of electroless copper. Unlike existing technologies, this invention can obtain high-bonding-strength, low-roughness ceramic-based copper-clad laminates while conserving precious metal catalysts. The ceramic substrates listed in this invention are only a portion commonly used in the art and are not limited to the non-oxide ceramic substrates mentioned herein. Appropriate modifications to the method of this invention are also applicable to oxide ceramic substrates. The metallization electroless copper deposition process exemplified in this invention is a conventional process for depositing metal on ceramic surfaces. It can employ publicly available electroless copper deposition processes or commercially available electroless copper deposition processes. No specific limitations are made in this invention, but any application of the intermediate layer design concept and the UV reduction process route should be within the scope of protection of this invention.

[0115] To achieve low roughness and high bonding strength in copper-clad laminates with various ceramic and even glass substrates, this invention introduces stacked nanoparticles between the ceramic substrate and the Cu layer. Utilizing their three-dimensional network structure, these nanoparticles aim to modify the original surface roughness while providing mechanical anchoring sites during the copper deposition process, achieving physical-mechanical locking and improving the bonding strength between the ceramic substrate and the Cu layer. Among the nanoparticles, those with inherent UV activation properties, such as titanium dioxide particles, are preferred to achieve "no precious metal activation," reducing costs. Another portion of the nanoparticles, such as silicon dioxide particles, contribute to the three-dimensional structure, further enhancing the bonding strength.

[0116] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing an aluminum nitride-based copper-clad laminate, characterized in that, The preparation method includes the following steps: 1) The surface of the aluminum nitride substrate is oxidized and then subjected to plasma bombardment to obtain a pretreated surface; The method for surface oxidation of aluminum nitride substrate includes: cleaning the aluminum nitride substrate, heating and oxidizing it, then cleaning and drying it; the plasma bombardment time is 20s-3min. 2) Prepare an intermediate gel layer by spin-coating the gel onto the surface of an aluminum nitride substrate; The method for preparing the gel includes: mixing titanium dioxide, silica sol and ethanol, and then mechanically stirring to prepare a mixed gel with an intermediate gel layer. 3) Dry and sinter the resulting substrate after spin coating; 4) The sintered substrate is subjected to ultraviolet-catalyzed chemical deposition of copper to obtain aluminum nitride-based copper clad laminate material; The ultraviolet catalytic chemical deposition method includes: irradiating the sintered sample with ultraviolet light, and then placing it in a chemical copper plating solution for chemical copper deposition; The ultraviolet light wavelength for ultraviolet irradiation is 360-380nm, the power is 6-10w, and the irradiation time is 20-30min; The chemical plating solution includes: copper sulfate pentahydrate 8-10 g / L, citric acid 20-22 g / L, sodium hypophosphite 40-45 g / L, boric acid 30-40 g / L, nickel sulfate hexahydrate 0.8-1 g / L, and potassium ferrocyanide 20-22 mg / L.

2. The preparation method according to claim 1, characterized in that, In step 2), the spin coating method includes: dropping the gel onto the surface of the aluminum nitride substrate, spin coating at a speed of 500-600 r / min using a spin coater, and holding for 10-15 seconds.

3. The preparation method according to claim 1, characterized in that, In step 3), the sintering method includes sintering the substrate coated with the intermediate gel layer at 450-550°C for 1-3 hours.

4. An aluminum nitride-based copper clad laminate, characterized in that, It is prepared by the method described in any one of claims 1 to 3.

5. A method for preparing a ceramic-based copper-clad laminate, characterized in that, Includes the following steps: S1. Plasma treatment is performed on the ceramic substrate; If non-oxide ceramics are used as the ceramic substrate, the non-oxide ceramics need to be subjected to air oxidation treatment. S2. Spin-coat the UV-reducing active sol containing nano-oxide particles onto the surface of the ceramic substrate from step S1 to prepare an intermediate layer. The method for preparing the UV-reducing active sol is as follows: titanium dioxide precursor, silicon dioxide nanoparticles or organosilane are uniformly dispersed in an alcohol solution, wherein the alcohol solution includes at least one of anhydrous ethanol and isopropanol, to obtain a mixed sol; S3. The substrate obtained after spin coating in step S2 is subjected to air sintering. S4. Perform ultraviolet chemical reduction deposition of copper on the sintered intermediate layer substrate to obtain a ceramic-based copper-clad laminate. The method for ultraviolet chemical reduction deposition of copper includes: placing the sintered ceramic substrate in a chemical copper plating solution for ultraviolet irradiation, followed by chemical deposition of copper; the chemical copper plating solution consists of: copper sulfate pentahydrate 8-10 g / L, citric acid 20-22 g / L, sodium hypophosphite 40-45 g / L, boric acid 30-40 g / L, nickel sulfate hexahydrate 0.8-1 g / L, potassium ferrocyanide 20-22 mg / L, and finally adjusting the pH to 9-10.

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