Method for compounding aluminum nitride substrate and resistance paste

Abstract

The invention discloses a compounding method of an aluminum nitride substrate and resistance paste, and relates to the technical field of aluminum nitride ceramic composite material preparation, and the compounding method comprises the following steps: preparing an aluminum nitride-based composite material with a gradient interface layer, and carrying out roughening treatment on the aluminum nitride-based composite material; carrying out doping treatment on the traditional domestic resistance paste; printing the doped and modified slurry on the surface of a substrate by adopting a screen printing machine; sintering the dried raw materials in a sintering furnace to prepare a composite material of the aluminum nitride substrate and the resistance paste; according to the invention, doping treatment is carried out on traditional domestic resistance paste, so that the fluidity of the paste is slowed down in a mode of increasing the softening and melting temperature of the paste or increasing the viscosity of the paste at high temperature, and migration and embedding of a glass phase to functional components at the sintering temperature of the paste are reduced; meanwhile, further movement, permeation and reaction of the glass towards the substrate at the slurry sintering temperature are reduced, and finally the purposes of improving the interface compatibility between the substrate and the resistance slurry and stabilizing the resistance are achieved.

Description

Technical Field

[0001] This invention relates to the field of aluminum nitride ceramic composite material preparation technology, specifically to a composite method of aluminum nitride substrate and resistive paste. Background Technology

[0002] Aluminum nitride ceramic materials possess high thermal conductivity, low dielectric loss, excellent mechanical properties, chemical corrosion resistance, and high-temperature resistance. Compared with similar ceramic materials, they exhibit higher thermal conductivity than Al₂O₃ and are non-toxic than BeO, thus becoming a focal point in the ceramic substrate material market. Aluminum nitride ceramic materials are considered ideal materials for next-generation heat dissipation substrates and electronic device packaging, with enormous application potential in the electronics industry.

[0003] However, currently, the specialized resistive pastes suitable for aluminum nitride substrates are mainly imported, and their prices are far higher than those of domestically produced traditional thick-film resistive pastes, significantly increasing production costs. At the same time, imported resistive pastes face supply chain instability risks, long delivery cycles, and are heavily influenced by international trade conditions. Domestically produced traditional thick-film resistive pastes also suffer from serious compatibility issues with aluminum nitride substrates, resulting in problems such as interface blistering, delamination, and low bonding strength after printing. Therefore, a composite method for aluminum nitride substrates and resistive pastes is needed to solve these problems. Summary of the Invention

[0004] The purpose of this invention is to provide a method for combining an aluminum nitride substrate with a resistor paste, so as to solve the problems existing in the prior art mentioned in the background section.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A method for bonding an aluminum nitride substrate with a resistor paste includes the following steps: S1: Prepare an aluminum nitride-based composite material with a gradient interface layer, and roughen the aluminum nitride-based composite material. S2: The fluidity of the traditional domestic resistance paste is reduced by doping it to increase the softening and melting temperature of the paste or to increase the viscosity of the paste at high temperature. S3: The modified paste is printed onto the substrate surface using a screen printing machine and then dried. S4: The dried raw materials are sintered in a sintering furnace to obtain a composite material of aluminum nitride substrate and resistor paste.

[0006] Preferably, in step S1, the aluminum nitride-based composite material consists of an AlN ceramic matrix and an in-situ formed AlN-Al2O3-Y3Al5O3 matrix. 12 Transition layer and Al2O3-Y3Al5O 12 Composition of composite surface layer.

[0007] Preferably, in step S1, the specific preparation steps of the aluminum nitride-based composite material are as follows: S11: Weigh 90-99% wt% AlN with a particle size D50 of 1-10 μm and 1%-10% wt% Y2O3 with a particle size D50 of 0.5-10 μm, and then add them together with the dispersant and solvent into a ball mill jar. Place the jar on a ball mill for ball milling and pulverization. Set the ball milling time to 5-36 hours. After ball milling, control the particle size D50 to 1-5 μm. S12: Add the dissolved plasticizer, binder and solvent into the ball mill jar, and continue to place it in the ball mill for mixing and ball milling. Set the ball milling time to 5~36H, and control the particle size D50 after ball milling to 1~5um. S13: Pump a slurry with a viscosity of 1600~8000 mPa.s into a casting machine for casting and shaping, and cut the slurry into AlN green ceramic sheets with the target length, width and thickness; S14: After the AlN green ceramic sheets are stacked, they are pressed together under warm isostatic pressing. The pressing pressure is 10~200Mpa and the pressing temperature is 30~90℃. S15: Degrease the pressed green ceramic sheet under a nitrogen atmosphere. The degreasing temperature is set at 400~500℃ and the degreasing time is set at 48~90H. The degreased sample is sintered under a nitrogen-hydrogen atmosphere. The sintering temperature is set at 1800~1900℃ and the high temperature holding time is 2~6H. S16: The AlN substrate is heat-treated in a furnace with controlled humidity and atmosphere. During the heating process, air with a certain humidity is introduced below 1000℃. This stage rapidly forms AlN-Al2O3-Y3Al5O 12 Transition layer; dry air is introduced at 1000~1200℃, during which dense, interlocking Al2O3-Y3Al5O3 is stably formed. 12 Composite surface layer.

[0008] Preferably, in step S16, in order to effectively control the thickness of the gradient interface layer, the holding time at the highest temperature is controlled at 0.5~1H. During the cooling process, nitrogen gas is introduced as a protective gas to effectively prevent the continuous expansion of the gradient interface layer. At the same time, the temperature is maintained at 800~1000℃ for 1~4H to effectively release the stress caused by the formation of new products due to in-situ growth, thereby achieving the purpose of tempering.

[0009] Preferably, in step S1, the roughening process is performed by grinding and polishing with a grinding device, and the surface roughness Ra is controlled at 0.2-0.8 μm.

[0010] Preferably, in step S2, the specific steps of the doping treatment are as follows: Based on the traditional domestic resistance paste formula, one or more of Al2O3, MnO2, ZnO and CaO are doped. The components are mixed evenly by grinding, and the total proportion of doped components does not exceed 20%.

[0011] Preferably, in step S3, the drying temperature is set to 90~130℃ and the drying time is set to 5~90min.

[0012] Preferably, in step S4, the peak temperature of sintering is set to 650-900℃, and the holding time is set to 0-60min.

[0013] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention slows down the fluidity of traditional domestic resistive paste by doping it, increasing the softening and melting temperature of the paste or increasing the viscosity of the paste at high temperatures. This reduces the migration and embedding of glass-phase functional components at the sintering temperature of the paste, and at the same time reduces the further movement, penetration and reaction of the glass-phase substrate at the sintering temperature of the paste. Ultimately, this invention aims to improve the interfacial compatibility between the substrate and the resistive paste and stabilize the resistance.

[0014] 2. This invention prepares an aluminum nitride-based composite material with a gradient interface layer, wherein the outermost surface of the aluminum nitride-based composite material is Al2O3-Y3Al5O 12 The composite surface layer can cut off the direct contact and reaction between the lead silicate glass in the paste and AlN, thereby solving the interface compatibility problem between the aluminum nitride substrate and the resistor paste and eliminating delamination and bulging phenomena. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the composite material structure prepared according to the present invention.

[0016] Figure 2 This is a SEM image of the aluminum nitride substrate of the present invention combined with the doped and modified domestic resistive paste.

[0017] In the figure: 1. AlN ceramic matrix; 2. Transition layer; 3. Composite surface layer; 4. Domestic resistive paste. Detailed Implementation

[0018] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0019] Please see Figure 1-2 The present invention provides the following technical solutions: A method for bonding an aluminum nitride substrate with a resistor paste includes the following steps: First, an aluminum nitride-based composite material with a gradient interface layer is prepared, and then roughened by grinding and polishing with a grinding machine to control the surface roughness Ra at 0.5 μm. The aluminum nitride-based composite material consists of an AlN ceramic matrix and an in-situ formed AlN-Al2O3-Y3Al5O3 matrix. 12 Transition layer and Al2O3-Y3Al5O 12 The composite surface layer consists of the following components and is prepared using the following steps: (1) Weigh 96% wt% AlN with a particle size D50 of 1.8 μm and 4% wt% Y2O3 with a particle size D50 of 0.8 μm, and then add them together with the dispersant and solvent into the ball mill jar. Place the jar on the ball mill for ball milling and pulverization. Set the ball milling time to 14 hours. After ball milling, the particle size D50 is controlled at 1.4 μm. (2) Add the dissolved plasticizer, binder and solvent into the ball mill jar, and continue to place it in the ball mill for mixing and ball milling. The ball milling time is set to 16 hours, and the particle size D50 after ball milling is controlled at 1.2 μm. (3) Pump the slurry with a viscosity of 4600 mPa.s into the casting machine for casting and shaping, and cut the slurry into AlN green ceramic sheets with the target length, width and thickness; (4) The AlN green ceramic sheets formed are stacked and then pressed under isostatic pressure at a pressure of 120 MPa and a temperature of 80°C. (5) The pressed green ceramic sheet was degreased under a nitrogen atmosphere. The degreasing temperature was set at 500℃ and the degreasing time was set at 76H. The degreased sample was sintered under a nitrogen-hydrogen atmosphere. The sintering temperature was set at 1850℃ and the high temperature holding time was 2H. (6) The AlN substrate is heat-treated in a heating furnace with controlled humidity and atmosphere. During the heating process, air with a certain humidity is introduced below 1000℃. During this stage, AlN-Al2O3-Y3Al5O is rapidly formed. 12 Transition layer; dry air is introduced at 1000~1200℃, during which dense, interlocking Al2O3-Y3Al5O3 is stably formed. 12 Composite surface layer; to effectively control the thickness of the gradient interface layer, the holding time at the highest temperature is controlled at 1 hour. During the cooling process, nitrogen gas is introduced as a protective gas to effectively prevent the continuous expansion of the gradient interface layer. At the same time, it is held at 950℃ for 4 hours to effectively release the stress caused by the formation of new products due to in-situ growth, thereby achieving the purpose of tempering and obtaining aluminum nitride-based composite material.

[0020] Based on the aluminum nitride-based composite material prepared by the above steps, a traditional domestically produced resistive paste is doped and then composited onto the aluminum nitride-based composite material. The specific steps are as follows: Example 1 (1) Based on the traditional domestic resistive paste formula, Al2O3 and MnO2 powders were doped, and the components were mixed evenly by grinding. The total proportion of doped components was 7.5%. (2) The modified paste was printed onto the substrate surface using a screen printing machine and dried at 120°C for 10 min. (3) Sintering is carried out in a sintering furnace with a peak temperature of 830℃ and a holding time of 10min.

[0021] The resistivity paste prepared in Example 1 showed no bulging or delamination, exhibited good adhesion in the cross-cut adhesion test, and showed a resistivity change rate of +2.5% after aging tests.

[0022] Example 2 (1) Based on the traditional domestic resistance paste formula, Al2O3, MnO2 and CaO powders were doped, and the components were mixed evenly by grinding. The total proportion of doped components was 7.5%. (2) The modified paste was printed onto the substrate surface using a screen printing machine and dried at 125°C for 15 min. (3) Sintering is carried out in a sintering furnace with a peak temperature of 830℃ and a holding time of 30min.

[0023] The resistivity paste prepared in Example 2 showed no bulging or delamination, exhibited good adhesion in the cross-cut adhesion test, and showed a resistivity change rate of +3% after aging test.

[0024] Example 3 (1) Al2O3 and MnO2 powders were doped into the traditional domestic resistive paste formula, and the components were mixed evenly by grinding. The total proportion of doped components was 10%. (2) The modified paste was printed onto the substrate surface using a screen printing machine and dried at 125°C for 15 min. (3) Sintering is carried out in a sintering furnace with a peak temperature of 850℃ and a holding time of 10min.

[0025] The resistivity paste prepared in Example 3 showed no bulging or delamination, exhibited good adhesion in the cross-cut adhesion test, and showed a resistivity change rate of -2.5% after aging tests.

[0026] Traditional aluminum nitride substrates exhibit interface bulging and delamination after applying domestically produced resistive paste. However, this invention, with its gradient interface layer, shows no such bulging or delamination when the surface of the aluminum nitride-based composite material is doped with modified domestically produced resistive paste. Furthermore, traditional aluminum nitride substrates show poor resistive paste adhesion, with significant detachment after cross-cut adhesion testing. In contrast, the aluminum nitride-based composite material with its gradient interface layer shows good resistive paste adhesion, with no detachment observed after cross-cut adhesion testing.

[0027] After applying domestically produced resistive paste to a traditional aluminum nitride substrate and undergoing aging tests, the resistivity change rate reaches 20%. However, after applying domestically produced resistive paste with a gradient interface layer to the surface of the aluminum nitride-based composite material of this invention and undergoing aging tests, the resistivity change rate is ≤±5%, which is comparable to the bonding performance of imported paste.

[0028] Traditional aluminum nitride substrates, when fitted with imported resistance paste, are expensive. The present invention, by applying domestically produced resistance paste with doping modification to the surface of aluminum nitride-based composite material with a gradient interface layer, greatly reduces costs. Moreover, the material is readily available, and the process is controllable, enabling large-scale implementation and application.

[0029] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for composite bonding of an aluminum nitride substrate and a resistive paste, characterized in that, Includes the following steps: S1: Prepare an aluminum nitride-based composite material with a gradient interface layer, and roughen the aluminum nitride-based composite material. S2: The fluidity of the traditional domestic resistance paste is reduced by doping it to increase the softening and melting temperature of the paste or to increase the viscosity of the paste at high temperature. S3: The modified paste is printed onto the substrate surface using a screen printing machine and then dried. S4: The dried raw materials are sintered in a sintering furnace to obtain a composite material of aluminum nitride substrate and resistor paste.

2. The method for composite aluminum nitride substrate and resistor paste according to claim 1, characterized in that: In step S1, the aluminum nitride-based composite material consists of an AlN ceramic matrix and an in-situ formed AlN-Al2O3-Y3Al5O3 matrix. 12 Transition layer and Al2O3-Y3Al5O 12 Composition of composite surface layer.

3. The method for composite aluminum nitride substrate and resistor paste according to claim 1, characterized in that, In step S1, the specific preparation steps of the aluminum nitride-based composite material are as follows: S11: Weigh 90-99% wt% AlN with a particle size D50 of 1-10 μm and 1%-10% wt% Y2O3 with a particle size D50 of 0.5-10 μm, and then add them together with the dispersant and solvent into a ball mill jar. Place the jar on a ball mill for ball milling and pulverization. Set the ball milling time to 5-36 hours. After ball milling, control the particle size D50 to 1-5 μm. S12: Add the dissolved plasticizer, binder and solvent into the ball mill jar, and continue to place it in the ball mill for mixing and ball milling. Set the ball milling time to 5~36H, and control the particle size D50 after ball milling to 1~5um. S13: Pump a slurry with a viscosity of 1600~8000 mPa.s into a casting machine for casting and shaping, and cut the slurry into AlN green ceramic sheets with the target length, width and thickness; S14: After the AlN green ceramic sheets are stacked, they are pressed together under warm isostatic pressing. The pressing pressure is 10~200Mpa and the pressing temperature is 30~90℃. S15: Degrease the pressed green ceramic sheet under a nitrogen atmosphere. The degreasing temperature is set at 400~500℃ and the degreasing time is set at 48~90H. The degreased sample is sintered under a nitrogen-hydrogen atmosphere. The sintering temperature is set at 1800~1900℃ and the high temperature holding time is 2~6H. S16: The AlN substrate is heat-treated in a furnace with controlled humidity and atmosphere. During the heating process, air with a certain humidity is introduced below 1000℃. This stage rapidly forms AlN-Al2O3-Y3Al5O 12 Transition layer; dry air is introduced at 1000~1200℃, during which dense, interlocking Al2O3-Y3Al5O3 is stably formed. 12 Composite surface layer.

4. The method for composite aluminum nitride substrate and resistor paste according to claim 3, characterized in that, In step S16, in order to effectively control the thickness of the gradient interface layer, the holding time at the highest temperature is controlled at 0.5~1H. During the cooling process, nitrogen gas is introduced as a protective gas to effectively prevent the continuous expansion of the gradient interface layer. At the same time, the temperature is maintained at 800~1000℃ for 1~4H to effectively release the stress caused by the formation of new products due to in-situ growth, thereby achieving the purpose of tempering.

5. The method for composite aluminum nitride substrate and resistor paste according to claim 1, characterized in that: In step S1, the roughening process involves polishing the surface using a grinding device, with the surface roughness Ra controlled between 0.2 and 0.8 μm.

6. The method for composite aluminum nitride substrate and resistor paste according to claim 1, characterized in that, In step S2, the specific steps of the doping treatment are as follows: Based on the traditional domestic resistance paste formula, one or more of Al2O3, MnO2, ZnO and CaO are doped. The components are mixed evenly by grinding, and the total proportion of doped components does not exceed 20%.

7. The method for composite aluminum nitride substrate and resistor paste according to claim 1, characterized in that, In step S3, the drying temperature is set to 90~130℃ and the drying time is set to 5~90min.

8. The method for composite aluminum nitride substrate and resistor paste according to claim 1, characterized in that, In step S4, the peak temperature of sintering is set to 650-900℃, and the holding time is set to 0-60min.

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