A method for preparing a high-reliability copper-clad ceramic circuit board

Abstract

The present invention discloses a method for preparing a high-reliability copper-clad ceramic circuit board, comprising: S1) preparing a copper-clad ceramic substrate; S2) laminating a dry film on the copper-clad ceramic substrate; S3) exposing and developing the dry film on the front of the copper-clad ceramic substrate; S4) etching the copper circuits on the copper-clad ceramic substrate; S5) removing the dry film on the copper-clad ceramic circuit board; S6) laser ablation of solder on the copper-clad ceramic circuit board: laser ablation equipment is introduced to perform laser ablation at specific locations according to the product's preset solder step dimensions and preset parameters, removing the solder and completing the preparation of the solder step structure; and S7) surface treatment and cleaning of the copper-clad ceramic circuit board. By introducing the laser ablation equipment, the present invention optimizes existing solder step preparation methods, reducing the use of dry film materials, developer, copper etching solution, and stripping chemicals in existing solutions, resulting in lower costs and greater environmental friendliness.

Description

Technical Field

[0001] The present invention relates to a method for preparing a circuit board, and in particular to a method for preparing a high-reliability copper-clad ceramic circuit board. Background Art

[0002] AMB copper-clad ceramic substrates, due to their high thermal conductivity and insulation properties, are widely used in semiconductor module device packaging with high power and high heat dissipation requirements. The production process of AMB copper-clad ceramic circuit boards primarily involves three raw materials: ceramic substrates, copper, and brazing material. Ceramics are typically silicon nitride, aluminum nitride, or aluminum oxide, typically with a thickness of ≤2mm. Brazing materials are typically silver-copper-titanium or copper-titanium alloys, typically with a thickness of ≤0.05mm. Copper is typically oxygen-free copper with a purity exceeding 99.9%, typically with a copper strip thickness of ≤2mm. The thermal expansion coefficients of these three raw materials differ significantly, leading to ceramic cracking and failure during severe temperature shock testing, making them unable to meet the high reliability requirements of products such as automotive. For high-reliability AMB copper-clad ceramic circuit board products, a common industry solution is to utilize existing etching processes to create stress-relieving brazing step structures in stress-concentrated areas such as line spacing to improve product reliability.

[0003] In the prior art, patent document CN116193724A discloses a method for using an existing etching process to generate a solder step to improve the reliability of a copper-clad ceramic circuit board. During the preparation process, this method requires repeating the existing etching process, which is a lengthy and cumbersome process. In addition, a chemical etching method is selected to remove copper to achieve solder step etching. The size is uncontrollable and the reliability is unstable. In addition, the amount of dry film material and copper etching liquid and other chemicals used increases, which increases the production cost and is not conducive to environmental protection. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the existing technology and provide a method for preparing a high-reliability copper-clad ceramic circuit board. By introducing laser ablation equipment, the existing solder step preparation method is optimized, and the use of dry film materials and developer, copper etching solution, and film removal solution in the existing solution is reduced, which is lower in cost and more environmentally friendly.

[0005] The object of the present invention is achieved as follows: A method for preparing a high-reliability copper-clad ceramic circuit board comprises the following steps:

[0006] S1) Preparation of copper-clad ceramic substrate: The ceramic substrate is bonded to high-purity oxygen-free copper using a high-temperature melt diffusion process to form a substrate.

[0007] S2) Dry film lamination of copper-clad ceramic substrate: A layer of photosensitive dry film is simultaneously covered on both sides of the copper-clad ceramic substrate by a laminator, and the image of the film is transferred to the board surface through exposure;

[0008] S3) Dry film exposure and development on the front side of the copper-clad ceramic substrate: A customized strip film is used for exposure. The portion not covered by the photoresist is removed during the development process to form the desired circuit pattern.

[0009] S4) Etching of copper circuits on copper-clad ceramic substrates: The copper surface exposed by dissolving the dry film is etched away with acidic copper chloride etching solution, removing the metal parts not protected by the photoresist, thereby forming a precise circuit pattern;

[0010] S5) Dry film removal of copper-clad ceramic circuit board: Place the copper-clad ceramic substrate after copper etching into the prepared quantitative alkaline solution for film removal;

[0011] S6) Laser ablation of solder on copper-clad ceramic circuit boards: By introducing laser ablation equipment, the laser ablation equipment performs laser ablation at specific locations according to the product's preset solder step size and preset parameters to remove the solder and complete the preparation of the solder step structure;

[0012] S7) Surface treatment and cleaning of copper-clad ceramic circuit boards: Sandblast the substrate circuits to roughen and clean the surface and remove surface oxides and dirt.

[0013] Furthermore, the step S6) specifically includes: placing the copper-clad ceramic circuit board on a workbench, turning on the vacuum suction to fix the product, using the CCD camera of the laser ablation device to identify the mark point on the product to achieve alignment, and then the laser ablation device performs laser ablation at a specific position according to the preset solder step size and preset parameters of the product to remove the solder. During the entire laser ablation process, a vacuum air knife and water cooling equipment are configured to ensure that the vaporized substances generated during the solder ablation process do not contaminate the surface of the copper-clad ceramic circuit board product. After the solder ablation is completed, the vacuum suction is turned off.

[0014] Furthermore, in the step S6), the laser pulse frequency range of the laser ablation is 50KHz-2000KHz; the laser scanning speed range is 10mm / s-2000mm / s.

[0015] Furthermore, the vacuum pressure range in step S6) is -0.08 MPa-0 MPa.

[0016] Furthermore, the temperature of the water cooling device is set to 0-20°C.

[0017] The present invention adopts the above technical scheme, and compared with the existing technology, the beneficial effects are as follows: 1) by introducing laser ablation equipment, the existing solder step preparation method is optimized, and the use of dry film materials and developer, copper etching solution, and film stripping solution in the existing scheme is reduced, which is lower in cost and more environmentally friendly; 2) by introducing laser ablation equipment, the existing solder step preparation method is optimized, and the dry film pressing, exposure, development, copper etching, and film stripping processes in the existing scheme are eliminated, the process is streamlined, and rapid preparation is achieved; 3) by introducing laser ablation equipment, the existing solder step preparation method is optimized, and the solder step etching size and appearance in the process of etching solder with existing chemical solutions are improved. Laser ablation is simple and controllable, and is not affected by the matching of solder etching solution and solder composition, which facilitates dimensional consistency and no solder residue in the solder step preparation process; 4) the copper-clad ceramic circuit board product containing solder step prepared by this method has no solder residue, controllable solder step size, and has stable high insulation properties and high reliability as measured. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Flowchart of the present invention.

[0019] Figure 2 Schematic diagram of the process of the preparation method of the present invention.

[0020] Among them, 01 oxygen-free copper, 02 brazing material, 03 ceramic substrate, 04 dry film. DETAILED DESCRIPTION

[0021] like Figure 1-2 A method for preparing a high-reliability copper-clad ceramic circuit board is shown, comprising the following steps:

[0022] S1) Preparation of copper-clad ceramic substrate: The ceramic substrate is bonded to high-purity oxygen-free copper using a high-temperature melt diffusion process to form a substrate.

[0023] S2) Dry film lamination of copper-clad ceramic substrate: A layer of photosensitive dry film is simultaneously covered on both sides of the copper-clad ceramic substrate by a laminator, and the image of the film is transferred to the board surface through exposure;

[0024] S3) Dry film exposure and development on the front side of the copper-clad ceramic substrate: A customized strip film is used for exposure. The portion not covered by the photoresist is removed during the development process to form the desired circuit pattern.

[0025] S4) Etching of copper circuits on copper-clad ceramic substrates: The copper surface exposed by dissolving the dry film is etched away with acidic copper chloride etching solution, removing the metal parts not protected by the photoresist, thereby forming a precise circuit pattern;

[0026] S5) Dry film removal of copper-clad ceramic circuit board: Place the copper-clad ceramic substrate after copper etching into the prepared quantitative alkaline solution for film removal;

[0027] S6) Laser ablation of solder on copper-clad ceramic circuit boards: By introducing laser ablation equipment to replace the existing copper etching process, the preparation of the solder step structure is completed. During the laser ablation process to remove the solder, the copper-clad ceramic circuit board is placed on the workbench and the vacuum suction is turned on to fix the product. The CCD camera of the laser ablation equipment is used to identify the mark points on the product for alignment. The laser ablation equipment then performs laser ablation at a specific position according to the preset solder step size and preset parameters of the product to remove the solder. During the entire laser ablation process, a vacuum air knife and water cooling equipment are configured to ensure that the vaporized substances generated during the solder ablation process do not contaminate the surface of the copper-clad ceramic circuit board product. After the solder ablation is completed, the vacuum suction is turned off.

[0028] The power range of the laser for laser ablation is 10W~1000W; the laser pulse frequency range is 50KHz~2000KHz; the laser pulse width is 10fs~10ms; the laser scanning speed range is 10mm / s-2000mm / s; the laser scanning interval is 0.01mm~0.2mm; the vacuum pressure range is -0.08MPa-0Mpa; the water cooling equipment temperature is set to 0-20℃.

[0029] S7) Surface treatment and cleaning of copper-clad ceramic circuit boards: Sandblast the substrate circuits to roughen and clean the surface and remove surface oxides and dirt.

[0030] The present invention discloses a method for preparing a high-reliability copper-clad ceramic circuit board. By introducing laser ablation equipment, the existing method for preparing a solder step is optimized, reducing the use of dry film materials and developer, copper etching solution, and film stripping solution in the existing solution, thereby reducing costs and being more environmentally friendly. The copper-clad ceramic circuit board product containing a solder step prepared by this method has no solder residue, the solder step size is controllable, and has stable high insulation properties and high reliability as measured.

[0031] The present invention is not limited to the above-mentioned embodiments. On the basis of the technical solutions disclosed in the present invention, those skilled in the art can make some substitutions and modifications to some of the technical features therein according to the disclosed technical content without creative labor, and these substitutions and modifications are all within the protection scope of the present invention.

Claims

1. A method for preparing a high-reliability copper-clad ceramic circuit board, characterized in that: The following steps are involved: S1) Preparation of copper-clad ceramic substrate: The ceramic substrate is bonded to high-purity oxygen-free copper using a high-temperature melt diffusion process to form a substrate; S2) Dry film lamination of copper-clad ceramic substrate: A layer of photosensitive dry film is simultaneously covered on both sides of the copper-clad ceramic substrate by a laminator, and the image of the film is transferred to the board surface through exposure; S3) Dry film exposure and development on the front side of the copper-clad ceramic substrate: A customized strip film is used for exposure. The portion not covered by the photoresist is removed during the development process to form the desired circuit pattern. S4) Etching of copper circuits on copper-clad ceramic substrates: The copper surface exposed by dissolving the dry film is etched away with acidic copper chloride etching solution, removing the metal parts not protected by the photoresist, thereby forming a precise circuit pattern; S5) Dry film removal of copper-clad ceramic circuit board: Place the copper-clad ceramic substrate after copper etching into the prepared quantitative alkaline solution for film removal; S6) Laser ablation of solder on copper-clad ceramic circuit boards: By introducing laser ablation equipment, the laser ablation equipment performs laser ablation at specific locations according to the product's preset solder step size and preset parameters to remove the solder and complete the preparation of the solder step structure; The step S6) specifically includes: placing the copper-clad ceramic circuit board on a workbench, turning on vacuum suction to fix the product, using a CCD camera of a laser ablation device to identify a mark on the product to achieve alignment, and then the laser ablation device performs laser ablation at a specific position according to a preset solder step size and preset parameters of the product to remove the solder. During the entire laser ablation process, a vacuum air knife and water cooling equipment are configured to ensure that vaporized substances generated during the solder ablation process do not contaminate the surface of the copper-clad ceramic circuit board product. After the solder ablation is completed, the vacuum suction is turned off; S7) Surface treatment and cleaning of copper-clad ceramic circuit boards: Sandblast the substrate circuits to roughen and clean the surface and remove surface oxides and dirt.

2. The method for preparing a high-reliability copper-clad ceramic circuit board according to claim 1, characterized in that: The laser pulse frequency range of the laser ablation in step S6) is 50KHz-2000KHz; the laser scanning speed range is 10mm / s-2000mm / s.

3. The method for preparing a high-reliability copper-clad ceramic circuit board according to claim 1, characterized in that: The pressure range of the vacuum suction in step S6) is -0.08 MPa to 0 MPa.

4. The method for preparing a high-reliability copper-clad ceramic circuit board according to claim 1, characterized in that: The temperature of the water cooling device is set to 0-20°C.

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