High-precision pattern half-etching processing technology for DCB substrate

Abstract

The invention relates to the technical field of electronic material and semiconductor manufacturing, and discloses a DCB substrate high-precision pattern half-etching processing technology. The method comprises the steps that S1, a DCB substrate is taken, cleaned, coarsened and washed with water; s2, a negative dry film is attached to the copper surface of the DCB substrate treated in the step S1 in a hot pressing mode to serve as an anti-etching mask; s3, designing a laser engraving pattern; s4, performing scanning exposure on the DCB substrate pressed and covered with the dry film in the step S2 by adopting laser direct imaging equipment according to the laser engraving pattern designed in the step S3; s5, developing the DCB substrate subjected to scanning exposure in the step S4 by using a developing solution to form a graphical anti-etching window; s6, immersing the DCB substrate developed in the step S5 into an etching solution, and etching the copper layer exposed from the anti-etching window; and S7, taking the DCB substrate after chemical etching in the step S6, removing the dry film, washing with water, and drying. The method has high precision and high flexibility, and the product quality is remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of electronic materials and semiconductor manufacturing technology, and discloses a high-precision pattern semi-etching process for DCB substrates. Background Technology

[0002] Direct-bonded copper substrates (DCBs) are widely used in power modules, LED packaging, automotive electronics, and other fields due to their excellent thermal conductivity, insulation, and mechanical strength. In these applications, it is often necessary to create specific patterns on the copper layer of the DCB and control the residual thickness of the copper layer (i.e., half-etching) to construct circuits, set chip bonding areas, or serve as buffer structures.

[0003] Currently, the mainstream process for DCB semi-etching is the "film exposure method," whose process is as follows: laminating dry film - creating film negative - exposing the film with ultraviolet light - developing - chemical etching - film removal. This method has the following inherent drawbacks: Limited by pattern complexity and accuracy: Due to the diffraction effect of ultraviolet light and the contact gap between the film and the dry film, this method is prone to jagged edges when etching fine lines or complex patterns. Even for simple patterns, it is difficult to guarantee edge smoothness, affecting product performance and reliability.

[0004] Limited alignment accuracy: The physical film expands and contracts due to changes in temperature and humidity, affecting the alignment accuracy with the substrate.

[0005] Image defect risk: Tiny gaps or dust between the film and dry film can cause exposure defects, affecting yield.

[0006] In addition, although some studies have attempted to use lasers to directly ablate copper layers, this method has problems such as a large heat-affected zone, uneven etching bottom, severe copper foil reflection, and low efficiency, making it difficult to achieve high-quality, controllable depth semi-etching.

[0007] Therefore, there is an urgent need in the field for a new DCB semi-etching method that can overcome the above-mentioned defects and achieve high precision, high flexibility and low cost. Summary of the Invention

[0008] The purpose of this invention is to provide a high-precision pattern semi-etching process for DCB substrates to solve the problems mentioned in the background art.

[0009] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a high-precision pattern semi-etching process for DCB substrates, comprising the following steps: S1: Pretreatment: Take the DCB substrate, clean, roughen, and wash with water to remove contaminants and enhance the adhesion of the dry film. S2: Dry film lamination: A negative dry film is hot-pressed onto the copper surface of the DCB substrate after the S1 pretreatment to serve as an etch-resistant mask. S3: Graphic Design: Design laser engraving graphics; In the graphic design stage, for areas that need to be semi-etched over a large area, design them as grid-like graphics composed of alternating transparent and opaque lines; After the grid-like graphics are directly imaged and developed by laser, corresponding grid-like anti-etching windows are formed on the dry film, thereby obtaining a flat and uniform semi-etched area during chemical etching. S4: Direct Laser Imaging: Using a direct laser imaging device, the DCB substrate with the dry film laminated in S2 is scanned and exposed according to the pattern designed in S3; the area scanned and exposed by the laser corresponds to the area where the copper layer needs to be removed later. S5: Development: The DCB substrate exposed by the S4 scan is developed using a developer to form a patterned anti-etching window; at this time, the dry film of the laser-exposed area (corresponding to the copper that needs to be retained) is cross-linked, cured and retained, while the dry film of the unexposed area (corresponding to the copper that needs to be etched, including the grid area) is dissolved, exposing the copper surface. S6: Chemical etching: Immerse the DCB substrate after S5 development in the etching solution to etch the copper layer exposed from the anti-etching window until the preset etching depth is reached to achieve half etching. The etching depth can be controlled by controlling the etching time. S7: Film Removal and Post-processing: Take the DCB substrate after S6 chemical etching, remove the dry film, wash with water and dry to obtain a semi-etched DCB substrate.

[0010] In a more optimized manner, in step S2, the process of laminating the dry film is as follows: temperature 100~120℃, pressure 0.3~0.5MPa; dry film thickness 40~45μm.

[0011] In a more optimized manner, step S4 employs a direct laser imaging device with a wavelength of 1064nm. The laser is an ultraviolet laser with a wavelength of 355~410nm. The laser power is 5~50W, the pulse frequency is 10~30kHz, and the processing speed is 5~10mm / s.

[0012] In a more optimized manner, in step S5, the developing solution is a 0.5~1.5wt% sodium carbonate aqueous solution, the developing temperature is 28~33℃, and the developing time is 30~60s.

[0013] In a more optimized manner, in step S6, the etching solution is copper chloride etching solution, the etching temperature is 40~55℃, and the etching rate is 8~15μm / min.

[0014] The optimal etching rate is 10 μm / min, the etching depth is 150 μm, and the etching time is controlled at 15 minutes.

[0015] In a more optimized manner, in step S7, a 4-5 wt% sodium hydroxide aqueous solution is used for membrane removal, and the membrane removal temperature is 50-55℃.

[0016] In a more optimized manner, the DCB micro-etching solution comprises the following raw materials: 25-40 g / L copper chloride, 50-100 g / L citric acid, 50-100 g / L potassium chloride, and the remainder being water.

[0017] In a more optimized manner, the DCB micro-etching solution further includes a polymeric regulator at a concentration of 0.5~1 g / L; The preparation of the polymer regulator includes the following steps: adding hydroxypropyl methylcellulose to N,N-dimethylformamide and stirring until homogeneous, heating to 95~110℃, adding carboxyl-terminated polyethylene glycol composition and nicotinic acid, stirring until homogeneous, adding tetrabutyl titanate, keeping warm and stirring for 7~8h, removing the solvent after the reaction is complete, and obtaining the polymer regulator.

[0018] In a more optimized manner, the polymeric regulator comprises the following raw materials: 0.5-1 parts hydroxypropyl methylcellulose, 80-120 parts N,N-dimethylformamide, 0.2-0.4 parts carboxyl-terminated polyethylene glycol composition, 1.5-2 parts nicotinic acid, and 0.1-0.2 parts tetrabutyl titanate.

[0019] More optimally, the carboxyl-terminated polyethylene glycol composition comprises carboxyl-terminated polyethylene glycol with a molecular weight of 5000-10000 and a molecular weight of 400-1000 in a mass ratio of (1-2):1.

[0020] Compared with the prior art, the beneficial effects achieved by the present invention are: (1) The quality of the graphic edge is significantly improved: Laser direct imaging has extremely high focusing ability and positioning accuracy, which can accurately restore digital graphics and effectively avoid the problem of jagged edges of graphics caused by light diffraction in traditional ultraviolet exposure, making the semi-etched graphic edge smooth and the outline clear.

[0021] High precision and high flexibility: Direct laser imaging eliminates the need for physical film, thus eliminating graphic errors caused by film expansion and contraction, resulting in higher alignment accuracy. Digital graphic files make graphic modification extremely convenient, making it particularly suitable for flexible production of small batches and diverse product varieties.

[0022] Significant cost-effectiveness: Eliminating the need to produce and replace expensive physical film reduces production and inventory management costs and shortens product development cycles.

[0023] Improved yield: Non-contact laser exposure avoids pattern defects caused by dust and film scratches, thus improving product yield.

[0024] Excellent semi-etching quality: By combining "laser patterning + chemical etching", the thermal damage and uneven bottom surface caused by direct laser ablation are avoided. The isotropic nature of chemical etching, combined with grid patterning design, can produce a semi-etched structure with smooth sidewalls and a flat and uniform bottom, with precise depth control.

[0025] (2) DCB micro-etching solution is used for roughening treatment, in which a polymeric regulator is added. This substance, with its high water solubility and high molecular weight, can be used as a morphology regulator in the system to improve the uniformity of roughening and help improve product quality. Hydroxypropyl methylcellulose can form a uniform adsorption layer on the copper surface, playing a mild and slow-release role. After grafting polyethylene glycol, it further improves the dispersibility and stability in water. The low molecular weight polyethylene glycol plays a role in assisting wetting and improving water solubility, while the high molecular weight polyethylene glycol plays a role in assisting corrosion inhibition and improving stability. At the same time, the polymeric regulator also incorporates the pyridine derivative nicotinic acid, which has the functions of complexing, leveling, and corrosion inhibition, improving the problem that the water solubility of traditional pyridine derivatives needs to be improved and the dispersion is uneven. The amount of this substance added needs to be controlled. Adding too much will increase the viscosity, which will affect the subsequent steps. Attached Figure Description

[0026] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 The DCB substrate after direct laser imaging in Example 1; Figure 2 This is a semi-etching effect diagram of the DCB substrate processed by the semi-etching process in Example 1. Figure 3 The half-etch width dimension of the DCB substrate in Example 1 is shown. Figure 4 The DCB substrate was fabricated using the film exposure method as shown in Comparative Example 1. Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] It should be noted that there are no special restrictions on the manufacturers of the raw materials involved in this invention. Exemplary examples include: nicotinic acid CAS: 59-67-6; hydroxypropyl methylcellulose: viscosity 80~120 mPa·s; carboxyl-terminated polyethylene glycol with molecular weight of 1000 / 5000: dicarboxyl polyethylene glycol, Tansh; negative dry film: Changchun LONGLITE photosensitive film; copper chloride etching solution: hydrochloric acid, sodium chlorate and copper ions, wherein the equivalent concentration of hydrochloric acid is 1.7±0.3N, the conductivity of sodium chlorate is 15~60, and the specific gravity of copper ions is 1.26~1.32. Unless otherwise specified, all figures below are parts by weight or mass ratios. Example 1: S1: Pretreatment: Take an Al2O3 ceramic substrate DCB with a copper foil thickness of 0.3mm, clean it with 5% sulfuric acid aqueous solution at 35℃ for 20s, roughen it with DCB micro-etching solution for 30s at 30℃, and wash it with water. S2: Dry film lamination: Under the conditions of temperature of 110℃ and pressure of 0.4MPa, a negative dry film with a thickness of 42μm is hot-pressed onto the copper surface of the DCB substrate after the pretreatment in step S1, as an anti-etching mask. S3: Graphic Design: Design laser-engraved graphics, with a laser window width of 40μm; S4: Direct Laser Imaging: Using a direct laser imaging device with a wavelength of 1064nm, the graphic input device control system designed in S3 is set to a laser power of 10W, a pulse frequency of 20kHz, and a processing speed of 20mm / s to scan and expose the DCB substrate with the dry film laminated in S2; the area scanned and exposed by the laser corresponds to the area that needs to be removed later. S5: Development: Spray development of the DCB substrate exposed by S4 scan using a sodium carbonate aqueous solution at 30℃ and a concentration of 1.0% for 50 seconds to form a patterned anti-etching window. S6: Chemical etching: The DCB substrate after S5 development is immersed in a copper chloride etching solution at a temperature of 50°C to etch the copper layer exposed from the anti-etching window; the etching depth is 150μm. S7: Film removal and post-treatment: The DCB substrate after S6 chemical etching is immersed in a 4% sodium hydroxide aqueous solution at 50°C for 150 seconds to remove the dry film. It is then washed with water and dried at high speed to obtain a semi-etched DCB substrate, which is used as a sample. The formula for DCB micro-etching solution is: 30g / L copper chloride, 70g / L citric acid, 80g / L potassium chloride, and the remainder is water.

[0029] Example 2: S1: Pretreatment: Take an Al2O3 ceramic substrate DCB with a copper foil thickness of 0.3mm, clean it with 5% sulfuric acid aqueous solution, roughen it with DCB micro-etching solution for 30s at 30℃, and wash it with water. S2: Dry film lamination: Under the conditions of temperature of 110℃ and pressure of 0.4MPa, a negative dry film with a thickness of 42μm is hot-pressed onto the copper surface of the DCB substrate after the pretreatment in step S1, as an anti-etching mask. S3: Graphic Design: Design laser-engraved graphics, with a laser window width of 40μm; S4: Direct Laser Imaging: Using a direct laser imaging device with a wavelength of 1064nm, the graphic input device control system designed in S3 is set to a laser power of 10W, a pulse frequency of 20kHz, and a processing speed of 20mm / s to scan and expose the DCB substrate with the dry film laminated in S2; the area scanned and exposed by the laser corresponds to the area that needs to be removed later. S5: Development: Spray development of the DCB substrate exposed by S4 scan using a sodium carbonate aqueous solution at 30℃ and a concentration of 1.0% for 50 seconds to form a patterned anti-etching window. S6: Chemical etching: The DCB substrate after S5 development is immersed in a copper chloride etching solution at a temperature of 50°C to etch the copper layer exposed from the anti-etching window; the etching depth is 150μm. S7: Film removal and post-treatment: The DCB substrate after S6 chemical etching is immersed in a 4% sodium hydroxide aqueous solution at 50°C for 150 seconds to remove the dry film. It is then washed with water and dried at high speed to obtain a semi-etched DCB substrate, which is used as a sample. The formula for DCB micro-etching solution is: 30 g / L copper chloride, 70 g / L citric acid, 80 g / L potassium chloride, 0.8 g / L polymer regulator, and the remainder is water; Preparation of the polymer regulator: 0.6 parts of hydroxypropyl methylcellulose were added to 100 parts of N,N-dimethylformamide and stirred evenly. The mixture was heated to 100°C, and 0.3 parts of carboxyl-terminated polyethylene glycol composition and 1.8 parts of nicotinic acid were added. After stirring evenly, 0.2 parts of tetrabutyl titanate were added, and the mixture was kept warm and stirred for 8 hours. After the reaction was completed, the solvent was removed to obtain the polymer regulator. The carboxyl-terminated polyethylene glycol composition consists of carboxyl-terminated polyethylene glycol with a molecular weight of 5000 and carboxyl-terminated polyethylene glycol with a molecular weight of 1000 in a mass ratio of 1:1.

[0030] Example 3: S1: Pretreatment: Take an Al2O3 ceramic substrate DCB with a copper foil thickness of 0.3mm, clean it with 5% sulfuric acid aqueous solution, roughen it with DCB micro-etching solution for 30s at 30℃, and wash it with water. S2: Dry film lamination: Under the conditions of temperature of 110℃ and pressure of 0.4MPa, a negative dry film with a thickness of 42μm is hot-pressed onto the copper surface of the DCB substrate after the pretreatment in step S1, as an anti-etching mask. S3: Graphic Design: Design laser-engraved graphics, with a laser window width of 40μm; S4: Direct Laser Imaging: Using a direct laser imaging device with a wavelength of 1064nm, the graphic input device control system designed in S3 is set to a laser power of 10W, a pulse frequency of 20kHz, and a processing speed of 20mm / s to scan and expose the DCB substrate with the dry film laminated in S2; the area scanned and exposed by the laser corresponds to the area that needs to be removed later. S5: Development: Spray development of the DCB substrate exposed by S4 scan using a sodium carbonate aqueous solution at 30℃ and a concentration of 1.0% for 50 seconds to form a patterned anti-etching window. S6: Chemical etching: The DCB substrate after S5 development is immersed in a copper chloride etching solution at a temperature of 50°C to etch the copper layer exposed from the anti-etching window; the etching depth is 150μm. S7: Film removal and post-treatment: The DCB substrate after S6 chemical etching is immersed in a 4% sodium hydroxide aqueous solution at 50°C for 150 seconds to remove the dry film. It is then washed with water and dried at high speed to obtain a semi-etched DCB substrate, which is used as a sample. The formula for DCB micro-etching solution is: 30 g / L copper chloride, 70 g / L citric acid, 80 g / L potassium chloride, 0.8 g / L polymer regulator, and the remainder is water; Preparation of the polymer regulator: 0.5 parts of hydroxypropyl methylcellulose were added to 100 parts of N,N-dimethylformamide and stirred evenly. The mixture was heated to 100°C, and 0.4 parts of carboxyl-terminated polyethylene glycol composition and 1.5 parts of nicotinic acid were added. After stirring evenly, 0.2 parts of tetrabutyl titanate were added. The mixture was kept warm and stirred for 8 hours. After the reaction was completed, the solvent was removed to obtain the polymer regulator. The carboxyl-terminated polyethylene glycol composition consists of carboxyl-terminated polyethylene glycol with a molecular weight of 5000 and carboxyl-terminated polyethylene glycol with a molecular weight of 1000 in a mass ratio of 1:1.

[0031] Comparative Example 1: Samples with the same pattern made by film exposure method: S1: Pretreatment: Take an Al2O3 ceramic substrate DCB substrate with a copper foil thickness of 0.3mm, clean it with 5% sulfuric acid aqueous solution at 35℃ for 20s, roughen it with DCB micro-etching solution for 30s at 30℃, and wash it with water. S2: Dry film lamination: Under the conditions of temperature of 110℃ and pressure of 0.4MPa, a negative dry film with a thickness of 42μm is hot-pressed onto the copper surface of the DCB substrate after the pretreatment in step S1, as an anti-etching mask. S3: Exposure: Ultraviolet exposure, exposure scale energy grid 7±1; S4: Development: The DCB substrate exposed in S3 is sprayed and developed using a sodium carbonate aqueous solution at 30°C and a concentration of 1.0% for 50 seconds to form patterned etch-resistant windows. S5: Chemical etching: The DCB substrate after S4 development is immersed in a copper chloride etching solution at a temperature of 50°C to etch the copper layer exposed from the anti-etching window; the etching depth is 150μm. S6: Film Removal and Post-processing: The DCB substrate after S5 chemical etching is immersed in a 4% sodium hydroxide aqueous solution at 50°C for 150 seconds to remove the dry film. After washing with water and high-speed drying, the sample prepared by the film exposure method is obtained.

[0032] Comparative Example 2 (using carboxyl-terminated polyethylene glycol with a molecular weight of 5000 instead of the carboxyl-terminated polyethylene glycol composition, the rest is the same as in Example 2): S1: Pretreatment: Take an Al2O3 ceramic-based DCB substrate with a copper foil thickness of 0.3 mm, clean it with 5% sulfuric acid aqueous solution, roughen it with DCB micro-etching solution for 30 s, temperature of 30 ℃, and wash it with water. S2: Dry film lamination: Under the conditions of temperature of 110℃ and pressure of 0.4MPa, a negative dry film with a thickness of 42μm is hot-pressed onto the copper surface of the DCB substrate after the pretreatment in step S1, as an anti-etching mask. S3: Graphic Design: Design laser-engraved graphics, with a laser window width of 40μm; S4: Direct Laser Imaging: Using a direct laser imaging device with a wavelength of 1064nm, the graphic input device control system designed in S3 is set to a laser power of 10W, a pulse frequency of 20kHz, and a processing speed of 20mm / s to scan and expose the DCB substrate with the dry film laminated in S2; the area scanned and exposed by the laser corresponds to the area that needs to be removed later. S5: Development: Spray development of the DCB substrate exposed by S4 scan using a sodium carbonate aqueous solution at 30℃ and a concentration of 1.0% for 50 seconds to form a patterned anti-etching window. S6: Chemical etching: The DCB substrate after S5 development is immersed in a copper chloride etching solution at a temperature of 50°C to etch the copper layer exposed from the anti-etching window; the etching depth is 150μm. S7: Film removal and post-treatment: The DCB substrate after S6 chemical etching is immersed in a 4% sodium hydroxide aqueous solution at 50°C for 150 seconds to remove the dry film. It is then washed with water and dried at high speed to obtain a semi-etched DCB substrate, which is used as a sample. The formula for DCB micro-etching solution is: 30 g / L copper chloride, 70 g / L citric acid, 80 g / L potassium chloride, 0.8 g / L polymer regulator, and the remainder is water; Preparation of the polymer regulator: 0.6 parts of hydroxypropyl methylcellulose were added to 100 parts of N,N-dimethylformamide and stirred until homogeneous. The mixture was heated to 100°C, and 0.3 parts of carboxyl-terminated polyethylene glycol with a molecular weight of 5000 and 1.8 parts of nicotinic acid were added. After stirring until homogeneous, 0.2 parts of tetrabutyl titanate were added. The mixture was kept warm and stirred for 8 hours. After the reaction was completed, the solvent was removed to obtain the polymer regulator.

[0033] Comparative Example 3 (using carboxyl-terminated polyethylene glycol with a molecular weight of 1000 instead of the carboxyl-terminated polyethylene glycol composition, the rest is the same as in Example 2): S1: Pretreatment: Take an Al2O3 ceramic-based DCB substrate with a copper foil thickness of 0.3 mm, clean it with 5% sulfuric acid aqueous solution, roughen it with DCB micro-etching solution for 30 s, temperature of 30 °C, and wash it with water. S2: Dry film lamination: Under the conditions of temperature of 110℃ and pressure of 0.4MPa, a negative dry film with a thickness of 42μm is hot-pressed onto the copper surface of the DCB substrate after the pretreatment in step S1, as an anti-etching mask. S3: Graphic Design: Design laser-engraved graphics, with a laser window width of 40μm; S4: Direct Laser Imaging: Using a direct laser imaging device with a wavelength of 1064nm, the graphic input device control system designed in S3 is set to a laser power of 10W, a pulse frequency of 20kHz, and a processing speed of 20mm / s to scan and expose the DCB substrate with the dry film laminated in S2; the area scanned and exposed by the laser corresponds to the area that needs to be removed later. S5: Development: Spray development of the DCB substrate exposed by S4 scan using a sodium carbonate aqueous solution at 30℃ and a concentration of 1.0% for 50 seconds to form a patterned anti-etching window. S6: Chemical etching: The DCB substrate after S5 development is immersed in a copper chloride etching solution at a temperature of 50°C to etch the copper layer exposed from the anti-etching window; the etching depth is 150μm. S7: Film removal and post-treatment: The DCB substrate after S6 chemical etching is immersed in a 4% sodium hydroxide aqueous solution at 50°C for 150 seconds to remove the dry film. It is then washed with water and dried at high speed to obtain a semi-etched DCB substrate, which is used as a sample. The formula for DCB micro-etching solution is: 30 g / L copper chloride, 70 g / L citric acid, 80 g / L potassium chloride, 0.8 g / L polymer regulator, and the remainder is water; Preparation of the polymer regulator: 0.6 parts of hydroxypropyl methylcellulose were added to 100 parts of N,N-dimethylformamide and stirred evenly. The mixture was heated to 100°C, and 0.3 parts of carboxyl-terminated polyethylene glycol with a molecular weight of 1000 and 1.8 parts of nicotinic acid were added. After stirring evenly, 0.2 parts of tetrabutyl titanate were added, and the mixture was kept warm and stirred for 8 hours. After the reaction was completed, the solvent was removed to obtain the polymer regulator.

[0034] Comparative Example 4 (using a mixture instead of a polymer modifier, the rest is the same as in Example 2): S1: Pretreatment: Take an Al2O3 ceramic-based DCB substrate with a copper foil thickness of 0.3 mm, clean it with a 5% sulfuric acid aqueous solution, roughen it with DCB micro-etching solution for 30 s at a temperature of 30 °C, and then wash it with water. S2: Dry film lamination: Under the conditions of temperature of 110℃ and pressure of 0.4MPa, a negative dry film with a thickness of 42μm is hot-pressed onto the copper surface of the DCB substrate after the pretreatment in step S1, as an anti-etching mask. S3: Graphic Design: Design laser-engraved graphics, with a laser window width of 40μm; S4: Direct Laser Imaging: Using a direct laser imaging device with a wavelength of 1064nm, the graphic input device control system designed in S3 is set to a laser power of 10W, a pulse frequency of 20kHz, and a processing speed of 20mm / s to scan and expose the DCB substrate with the dry film laminated in S2; the area scanned and exposed by the laser corresponds to the area that needs to be removed later. S5: Development: Spray development of the DCB substrate exposed by S4 scan using a sodium carbonate aqueous solution at 30℃ and a concentration of 1.0% for 50 seconds to form a patterned anti-etching window. S6: Chemical etching: The DCB substrate after S5 development is immersed in a copper chloride etching solution at a temperature of 50°C to etch the copper layer exposed from the anti-etching window; the etching depth is 150μm. S7: Film removal and post-treatment: The DCB substrate after S6 chemical etching is immersed in a 4% sodium hydroxide aqueous solution at 50°C for 150 seconds to remove the dry film. It is then washed with water and dried at high speed to obtain a semi-etched DCB substrate, which is used as a sample. The formula for DCB micro-etching solution is: 30 g / L copper chloride, 70 g / L citric acid, 80 g / L potassium chloride, 0.8 g / L of mixture, and the remainder is water; Preparation of the mixture: 0.6 parts of hydroxypropyl methylcellulose, 0.3 parts of carboxyl-terminated polyethylene glycol composition, and 1.8 parts of nicotinic acid are mixed to obtain a mixture; the carboxyl-terminated polyethylene glycol composition is a mixture of carboxyl-terminated polyethylene glycol with a molecular weight of 5000 and carboxyl-terminated polyethylene glycol with a molecular weight of 1000 in a mass ratio of 1:1.

[0035] Comparative Example 5 (increase the amount of polymer regulator, the rest is the same as Example 2): S1: Pretreatment: Take an Al2O3 ceramic-based DCB substrate with a copper foil thickness of 0.3 mm, clean it with 5% sulfuric acid aqueous solution, roughen it with DCB micro-etching solution for 30 s, temperature of 30 ℃, and wash it with water. S2: Dry film lamination: Under the conditions of temperature of 110℃ and pressure of 0.4MPa, a negative dry film with a thickness of 42μm is hot-pressed onto the copper surface of the DCB substrate after the pretreatment in step S1, as an anti-etching mask. S3: Graphic Design: Design laser-engraved graphics, with a laser window width of 40μm; S4: Direct Laser Imaging: Using a direct laser imaging device with a wavelength of 1064nm, the graphic input device control system designed in S3 is set to a laser power of 10W, a pulse frequency of 20kHz, and a processing speed of 20mm / s to scan and expose the DCB substrate with the dry film laminated in S2; the area scanned and exposed by the laser corresponds to the area that needs to be removed later. S5: Development: Spray development of the DCB substrate exposed by S4 scan using a sodium carbonate aqueous solution at 30℃ and a concentration of 1.0% for 50 seconds to form a patterned anti-etching window. S6: Chemical etching: The DCB substrate after S5 development is immersed in a copper chloride etching solution at a temperature of 50°C to etch the copper layer exposed from the anti-etching window; the etching depth is 150μm, and a semi-etched DCB substrate is obtained, which is used as a sample. S7: Film removal and post-treatment: Immerse the DCB substrate after S6 chemical etching in a 4% sodium hydroxide aqueous solution at 50°C for 150 seconds to remove the dry film, then wash with water and dry at high speed. The formula for DCB micro-etching solution is: 30 g / L copper chloride, 70 g / L citric acid, 80 g / L potassium chloride, 1.5 g / L polymer regulator, and the remainder is water; Preparation of the polymer regulator: 0.6 parts of hydroxypropyl methylcellulose were added to 100 parts of N,N-dimethylformamide and stirred evenly. The mixture was heated to 100°C, and 0.3 parts of carboxyl-terminated polyethylene glycol composition and 1.8 parts of nicotinic acid were added. After stirring evenly, 0.2 parts of tetrabutyl titanate were added, and the mixture was kept warm and stirred for 8 hours. After the reaction was completed, the solvent was removed to obtain the polymer regulator. The carboxyl-terminated polyethylene glycol composition consists of carboxyl-terminated polyethylene glycol with a molecular weight of 5000 and carboxyl-terminated polyethylene glycol with a molecular weight of 1000 in a mass ratio of 1:1.

[0036] Performance testing: Samples prepared in Examples 1-3 and Comparative Examples 1-5 were used to test the actual etching depth of the semi-etched pattern at multiple random points using a 3D profilometer. The actual etching depth was compared with the theoretical etching depth, and the error rate was calculated. See Table 1 for details. Table 1:

[0037] In summary, measurements show that the bottom of the semi-etched DCB substrate is flat. Due to the use of high-precision laser direct imaging, even complex patterns can meet the process requirements of the soldering area for high-reliability power devices.

[0038] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-precision pattern semi-etching process for DCB substrates, characterized in that: Includes the following steps: S1: Pre-treatment: Take the DCB substrate, clean, roughen, and wash with water; S2: Dry film lamination: A negative dry film is hot-pressed onto the copper surface of the DCB substrate after the S1 pretreatment to serve as an etch-resistant mask. S3: Graphic Design: Designing laser-engraved graphics; S4: Direct Laser Imaging: Using a direct laser imaging device, the DCB substrate with dry film laminated in S2 is scanned and exposed according to the laser engraving pattern designed in S3. S5: Development: The DCB substrate exposed by the S4 scan is developed using a developer to form a patterned etch-resistant window; S6: Chemical etching: Immerse the DCB substrate after S5 development in the etching solution to etch the copper layer exposed from the anti-etching window. S7: Film Removal and Post-processing: Take the DCB substrate after S6 chemical etching, remove the dry film, wash with water and dry to obtain a semi-etched DCB substrate.

2. The high-precision patterned semi-etching process of a DCB substrate according to claim 1, wherein: In step S1, a 3-6 wt% sulfuric acid aqueous solution is used for cleaning; and a DCB micro-etching solution is used for roughening treatment.

3. The high-precision pattern semi-etching process for DCB substrates according to claim 1, characterized in that: In step S2, the process of laminating the dry film is as follows: temperature 100~120℃, pressure 0.3~0.5MPa; negative dry film thickness is 40~45μm.

4. The high-precision pattern semi-etching process for a DCB substrate according to claim 1, characterized in that: In step S4, a direct laser imaging device with a wavelength of 1064nm is used. The laser is an ultraviolet laser with a wavelength of 355~410nm. The laser power is 5~50W, the pulse frequency is 10~30kHz, and the processing speed is 5~10mm / s.

5. The high-precision pattern semi-etching process for a DCB substrate according to claim 1, characterized in that: In step S5, the developing solution is a 0.5~1.5wt% sodium carbonate aqueous solution, the developing temperature is 28~33℃, and the developing time is 30~60s.

6. The high-precision pattern semi-etching process for a DCB substrate according to claim 1, characterized in that: In step S6, the etching solution is copper chloride etching solution, the etching temperature is 40~55℃, and the etching rate is 8~15μm / min.

7. The high-precision pattern semi-etching process for DCB substrates according to claim 1, characterized in that: In step S7, a 4-5 wt% sodium hydroxide aqueous solution is used for membrane removal.

8. The high-precision pattern semi-etching process for a DCB substrate according to claim 2, characterized in that: The DCB micro-etching solution comprises the following raw materials: 25-40 g / L copper chloride, 50-100 g / L citric acid, 50-100 g / L potassium chloride, and the remainder is water.

9. The high-precision pattern semi-etching process for a DCB substrate according to claim 8, characterized in that: The DCB micro-etching solution also includes a polymer regulator of 0.5~1g / L; The preparation of the polymer regulator includes the following steps: adding hydroxypropyl methylcellulose to N,N-dimethylformamide and stirring until uniform; heating to 95~110℃; adding carboxyl-terminated polyethylene glycol composition and nicotinic acid; stirring until uniform; adding tetrabutyl titanate; keeping warm and stirring for 7~8h; removing the solvent after the reaction is complete to obtain the polymer regulator. The polymeric regulator comprises the following raw materials: 0.5-1 parts hydroxypropyl methylcellulose, 80-120 parts N,N-dimethylformamide, 0.2-0.4 parts carboxyl-terminated polyethylene glycol composition, 1.5-2 parts nicotinic acid, and 0.1-0.2 parts tetrabutyl titanate.

10. The high-precision pattern semi-etching process for a DCB substrate according to claim 9, characterized in that: The carboxyl-terminated polyethylene glycol composition is composed of carboxyl-terminated polyethylene glycol with a molecular weight of 5000-10000 and a molecular weight of 400-1000 in a mass ratio of (1-2):1.

Images