A method for preparing fine ceramic circuit boards by laser-assisted chemical plating

Abstract

The present invention relates to the technical field of chemical copper plating of ceramic substrates, and specifically belongs to a method for preparing fine ceramic circuit boards by laser-assisted chemical plating, and the process is as follows: using a degreasing liquid to remove oil stains on the surface of a ceramic substrate, using a laser to perform high-resolution physical roughening of the ceramic surface, using the activation liquid provided by the present invention to activate after degreasing, adsorbing copper active particles on the roughened surface, and then using the chemical plating liquid provided by the present invention to perform chemical copper plating, thereby obtaining high-resolution metallized lines. The ceramic substrate chemical plating method provided by the present invention does not require the use of corrosive reagents such as hydrofluoric acid, nitric acid, and sodium hydroxide that are harmful to the environment and human body, nor does it require the use of precious metals such as silver, palladium, and gold as active sites, and can achieve low-cost, high-precision fine metallization of ceramic surfaces under more environmentally friendly and simple conditions, and achieve the required electrical interconnection function.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical copper plating on ceramic substrates, and specifically refers to a method for preparing a fine ceramic circuit board by laser-assisted chemical plating. Background Art

[0002] Chemical plating can achieve metallization of non-metallic surfaces by driving the self-catalytic deposition of metal atoms in the solution through a strong reducing agent without applying an external current. However, due to the surface inertness of ceramic materials, it is impossible to directly catalyze the chemical plating reaction, so a complex pre-treatment process is required, which mainly includes four steps: degreasing, roughening, sensitization and activation.

[0003] The traditional roughening method requires the use of highly corrosive solvents combined with high temperatures to etch ceramic materials. Usually, there are three types of solvents, NaOH, HNO3 and HF. These methods are very harmful to the human body and the environment, and do not meet the relevant requirements of green environmental protection. In addition, the above roughening methods will corrode the entire ceramic substrate, and there is no regional selectivity, and fine processing cannot be achieved. In addition, the chemical plating activation process currently used usually uses precious metals such as palladium, gold, and silver as catalytic active sites to induce the chemical plating reaction, which will cause a substantial increase in the cost of chemical plating. In addition, the activation process is complicated, and the chemicals used, such as stannous chloride, silver nitrate, and palladium chloride, will cause serious environmental pollution.

[0004] After laser ablation, the aluminum nitride ceramic substrate can generate a conductive aluminum metal layer, which can directly catalyze the chemical copper plating reaction. For example, CN103188877A discloses a method for chemically plating aluminum nitride ceramic circuit boards. After laser ablation, a metal layer can be directly deposited on the surface of the aluminum nitride ceramic, but this mechanism cannot be repeated on an alumina ceramic substrate. The catalytic activity of the alumina ceramic substrate after laser ablation is not sufficient to drive the chemical copper plating reaction. By using the idea of ​​directional adsorption of active particles in the laser scanning area, active particles can be introduced on the surface of the ceramic substrate, weakening the influence of the composition and properties of the ceramic substrate on the chemical copper plating reaction, which is a metallization method with better compatibility.

[0005] Based on this, the present invention proposes a chemical plating pre-treatment method combining laser roughening with copper activation to solve the above-mentioned problems, and realizes the preparation of high-precision metallization layers on the surfaces of different ceramic substrates through the precise adsorption of active particles on the laser scanning area. Summary of the invention

[0006] The technical problem to be solved by the present invention is to address the defects of the background technology. For example, the present invention proposes a method for preparing fine ceramic circuit boards by laser-assisted chemical plating, which uses laser roughening to replace strong corrosive liquid roughening, and uses copper activation to replace precious metal activation. The ceramic surface chemical plating pretreatment process can be achieved in a convenient, harmless and low-cost manner.

[0007] The present invention adopts the following technical solution to solve the above technical problems: a method for preparing fine ceramic circuit boards by laser-assisted chemical plating, comprising the following steps:

[0008] Step 1: Surface degreasing: Use degreasing liquid to remove oil stains on the surface of the ceramic substrate;

[0009] Step 2: Laser roughening, using a laser to selectively physically roughen the surface of the ceramic substrate;

[0010] Step 3: Surface activation, using an activation solution to activate the surface of the ceramic substrate, and adsorbing active sites on the laser-roughened surface of the ceramic material, wherein the activation solution contains nano-copper particles and a silane coupling agent, and the nano-copper particles in the activation solution are prepared by a reduction method;

[0011] Step 4: Clean the activated ceramic substrate with deionized water;

[0012] Step 5: chemical copper plating, using a chemical plating solution to deposit copper on the activated ceramic substrate, wherein the chemical plating solution contains copper sulfate pentahydrate as a main salt, formaldehyde as a reducing agent, disodium ethylenediaminetetraacetate and sodium potassium tartrate as complexing agents, and potassium ferrocyanide and 2,2'-bipyridine as trace additives;

[0013] Step 6: After cleaning and drying, fine metallized lines are obtained on the ceramic surface.

[0014] Preferably, the laser roughening step is to irradiate the designed metal pattern with a laser to form physical roughening, the laser power is 5W, the scanning speed is 200mm / s, the frequency is 100KHz, the pulse width is 2μs, and the laser wavelength is 355nm.

[0015] Preferably, the formula of the degreasing liquid is 30g / LNaOH, 10g / LNa2CO3, the temperature is 60°C, and the processing time is 10min.

[0016] Preferably, the preparation method of the activation solution is as follows: dissolve copper sulfate pentahydrate in deionized water, add anhydrous ethanol 2.3 times the volume of deionized water, heat to 80°C under stirring conditions, keep warm for 30 minutes and then filter, continue to heat the filtered solution to 80°C, add 15-20g / L ascorbic acid under stirring conditions, add 0.02vol% silane coupling agent after a certain period of reduction, and continue the reaction for 40 minutes.

[0017] More preferably, during the preparation of the activation solution, the copper ions need to be reduced to the greatest extent, and the reduction time is at least 30 minutes.

[0018] More preferably, during the preparation of the activation solution, the silane coupling agent consists of γ-aminopropyltriethoxysilane and γ-glycidyloxypropyltrimethoxysilane.

[0019] More preferably, during the preparation of the activation solution, magnetic stirring is used to achieve solution convection.

[0020] More preferably, the copper activation step requires suspending the ceramic substrate in the activation solution, performing ultrasonic assisted activation for 10 minutes, and standing for 5 minutes to achieve the attachment of copper particles.

[0021] Preferably, the cleaning step requires the use of a slow water flow to remove residual copper particles on the ceramic surface and prevent unnecessary chemical copper plating reactions from occurring in the plating solution, thereby extending the service life of the plating solution.

[0022] Preferably, the preparation method of the chemical plating solution is: dissolving copper sulfate pentahydrate in deionized water to obtain a copper sulfate solution with a concentration of 16 g / L, and sequentially adding a complexing agent of 18.75 g / L disodium ethylenediaminetetraacetate, 16 g / L potassium sodium tartrate and an additive of 0.0125 g / L potassium ferrocyanide, 0.2 g / L 2,2 ’ -bipyridine, 0.016 vol% formaldehyde was added as a reducing agent after appropriate stirring, and the pH was adjusted to 11 using sodium hydroxide.

[0023] More preferably, the pH of the chemical plating solution needs to be adjusted to between 12.0 and 12.2 before actual use to ensure that the chemical plating process continues and to prevent the chemical plating reaction from being stopped midway due to a decrease in pH value.

[0024] More preferably, in the chemical copper plating step, the ceramic substrate needs to be suspended in the chemical plating solution, the plating bath temperature is maintained at 65° C., and the plating solution is slowly stirred.

[0025] Preferably, in the cleaning step, the ceramic substrate needs to be ultrasonically cleaned for 3 minutes and rinsed with deionized water to remove chemical reagents adsorbed on the surface.

[0026] Preferably, in the drying step, the drying temperature is 70-80° C. and the drying time is 40-60 min.

[0027] Compared with the prior art, the present invention adopts the above technical solution and has the following beneficial effects:

[0028] 1. The present invention provides a method for preparing fine ceramic circuit boards by laser-assisted chemical plating, which uses a laser to roughen the ceramic substrate. It is a physical roughening method that does not require the use of highly corrosive chemicals, reduces harm to the environment and human body, and is a more environmentally friendly processing method.

[0029] 2. The method of preparing fine ceramic circuit boards by laser-assisted chemical plating provided by the present invention can achieve selective roughening of designated areas. Compared with traditional corrosive roughening, it has high processing accuracy and strong designability.

[0030] 3. The present invention provides a method for preparing fine ceramic circuit boards by laser-assisted chemical plating, which uses copper particles to replace precious metals such as palladium, gold, and silver to catalyze the chemical plating reaction. The chemical reagents used are low-priced, which greatly reduces the cost of chemical copper plating.

[0031] 4. The method of preparing fine ceramic circuit boards by laser-assisted chemical plating provided by the present invention simplifies the pre-treatment process of chemical plating of ceramic materials and combines the sensitization and activation processes into one. After laser roughening and degreasing, only simple copper activation is required to achieve chemical plating activation treatment, which reduces the process complexity of chemical copper plating of ceramic materials and has high compatibility, and can realize the preparation of fine metallization layers on the surfaces of various ceramic substrates.

[0032] 5. The present invention provides a method for preparing fine ceramic circuit boards by laser-assisted chemical plating, which can directly achieve high-resolution copper deposition in a specified area and achieve the required electrical properties without the need for further metallization layer removal processing.

[0033] 6. The method of preparing fine ceramic circuit boards by laser-assisted chemical plating provided by the present invention is also applicable to the metallization of the inner walls of laser-punched holes on ceramic substrates, and can simultaneously realize the metallization of the ceramic surface and the metallization of the inner walls of the through holes under single activation and plating conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0035] Figure 1 An optical image of the copper activated fine chemical plating layer on the ceramic substrate of the present invention;

[0036] Figure 2 An optical image of a local area of ​​the copper activated fine chemical plating layer of the ceramic substrate of the present invention;

[0037] Figure 3 An optical image of a ceramic substrate having through-hole interconnection and redistribution circuits prepared by the method for preparing fine ceramic circuit boards by laser-assisted chemical plating according to the present invention;

[0038] Figure 4 An optical image of a cross section of a through-hole interconnect structure prepared by the method for preparing a fine ceramic circuit board by laser-assisted chemical plating according to the present invention;

[0039] Figure 5 This is a scanning electron microscope image of the surface of the copper activated fine chemical plating layer of the ceramic substrate of the present invention;

[0040] Figure 6 This is a scanning electron microscope image of the cross section of the copper activated fine chemical plating layer on the ceramic substrate of the present invention. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] Reference Figure 1-Figure 6 The present invention discloses a method for preparing a fine ceramic circuit board by laser-assisted chemical plating, comprising the following steps:

[0043] Step 1: Surface degreasing: Use degreasing liquid to remove oil stains on the surface of the ceramic substrate;

[0044] Step 2: Laser roughening, using a laser to selectively physically roughen the surface of the ceramic substrate;

[0045] Step 3: Surface activation, using an activation solution to activate the surface of the ceramic substrate, and adsorbing active sites on the laser-roughened surface of the ceramic material, wherein the activation solution contains nano-copper particles and a silane coupling agent, and the nano-copper particles in the activation solution are prepared by a reduction method;

[0046] Step 4: Clean the activated ceramic substrate with deionized water;

[0047] Step 5: chemical copper plating, using a chemical plating solution to deposit copper on the activated ceramic substrate, wherein the chemical plating solution contains copper sulfate pentahydrate as a main salt, formaldehyde as a reducing agent, disodium ethylenediaminetetraacetate and sodium potassium tartrate as complexing agents, and potassium ferrocyanide and 2,2'-bipyridine as trace additives;

[0048] Step 6: After cleaning and drying, fine metallized lines are obtained on the ceramic surface.

[0049] In step 1, the formula of the degreasing liquid is 30 g / L sodium hydroxide, 10 g / L sodium carbonate, the temperature is 60° C., and the processing time is 10 min.

[0050] In step 2, laser roughening is to use a laser to radiate the designed metallization pattern on the surface of the ceramic substrate to form physical roughening, wherein the laser power is 5W, the scanning speed is 200mm / s, the frequency is 100KHz, the pulse width is 2μs, and the laser wavelength is 355nm.

[0051] In step 3, the preparation method of the activation solution is as follows: dissolve copper sulfate pentahydrate in deionized water, add anhydrous ethanol 2.3 times the volume of deionized water, heat to 80°C under stirring conditions, keep warm for 30 minutes and then filter, continue to heat the filtered solution to 80°C, add 15-20g / L ascorbic acid under stirring conditions, add 0.02vol% silane coupling agent after a certain period of reduction, and continue to react for 40 minutes. Wherein, the silane coupling agent is composed of two types: γ-aminopropyl triethoxysilane (KH550) and γ-glycidyloxypropyl trimethoxysilane (KH560).

[0052] In step three, the copper activation step requires suspending the ceramic substrate in the activation solution, activating it with ultrasonic assistance for 10 minutes, and letting it stand for 5 minutes to achieve the adhesion of copper particles.

[0053] In step 4, the cleaning step requires the use of a slow water flow to remove the residual copper particles on the ceramic surface and prevent unnecessary chemical copper plating reactions from occurring in the plating solution, thereby extending the service life of the plating solution.

[0054] In step 5, the preparation method of the chemical plating solution is as follows: dissolve copper sulfate pentahydrate in deionized water to obtain a copper sulfate solution with a concentration of 16 g / L, and add 18.75 g / L of ethylenediaminetetraacetic acid disodium, 16 g / L of potassium sodium tartrate and additives 0.0125 g / L of potassium ferrocyanide, 0.2 g / L of 2,2 ’ -bipyridine, add 0.016 vol% formaldehyde as a reducing agent after appropriate stirring, and adjust the pH to 11 using sodium hydroxide.

[0055] In step 5, the pH of the chemical plating solution needs to be adjusted to between 12.0 and 12.2 before actual use to ensure that the chemical plating process continues and to prevent the chemical plating reaction from being stopped midway due to a drop in pH.

[0056] In step five, in the chemical copper plating step, the ceramic substrate needs to be suspended in the chemical plating solution, the plating bath temperature is maintained at 65° C., and the plating solution is slowly stirred.

[0057] In step six, in the cleaning step, the ceramic substrate needs to be ultrasonically cleaned for 3 minutes and rinsed with deionized water to remove surface adsorption and chemical reagents. The drying temperature is 70-80° C. and the drying time is 40-60 minutes.

[0058] Example 1

[0059] (1) Preparatory step: Prepare several 15×15 mm alumina ceramic substrates, ultrasonically clean them in alcohol for 3 min, and prepare the patterns to be processed by laser.

[0060] (2) Oil removal treatment: 3 g of sodium hydroxide and 1 g of sodium carbonate were dissolved in 100 mL of deionized water, heated to 60°C, placed in the laser-roughened ceramic substrate, ultrasonicated for 10 min, rinsed with deionized water, and placed in a 70°C oven for 30 min.

[0061] (3) Laser roughening: Import the metallization pattern to be printed into the laser control software, set the laser scanning speed to 200 mm / s, the laser frequency to 100 kHz, the pulse width to 2 μs, and the wavelength to 355 nm, turn on the laser red trace, place the ceramic substrate in the laser red trace area, ensure that the red trace area is in the center of the ceramic substrate, adjust the laser focal length, focus the laser on the upper surface of the ceramic substrate, and start laser laser.

[0062] (4) Preparation of activation solution: Dissolve 1g of copper sulfate pentahydrate in 30mL of deionized water. After fully dissolved, add 70mL of anhydrous ethanol while stirring, heat to 80°C in a water bath, keep warm for 30min, and then filter. Continue to heat the filtered solution to 80°C. Dissolve 0.5% ascorbic acid in 20mL of deionized water to obtain a reducing solution. While stirring, slowly drop the reducing solution into the filtered solution. After reducing for 30min, add 1.5mL of γ-aminopropyltriethoxysilane (KH550) silane coupling agent, and then add 0.5mL of γ-glycidyloxypropyltrimethoxysilane (KH560) silane coupling agent 3min later. Continue the reaction for 40min.

[0063] (5) Copper activation treatment: The ceramic substrate was suspended in the activation solution, immersed in ultrasound-assisted solution for 10 min, and allowed to stand for 5 min.

[0064] (6) Cleaning: Rinse the activated ceramic substrate slowly with deionized water to remove the active particles that are not firmly attached to the surface, and absorb the residual moisture with dust-free paper to extend the service life of the plating solution.

[0065] (7) Preparation of chemical plating solution: Weigh 2.56 g of copper sulfate pentahydrate and dissolve it in 160 mL of deionized water. Add 3 g of disodium ethylenediaminetetraacetate, 2.56 g of potassium sodium tartrate, 0.002 g of potassium ferrocyanide and 0.032 g of 2,2'-bipyridine in sequence. After proper stirring, add 2.56 mL of formaldehyde as a reducing agent and adjust the pH to 11 with sodium hydroxide.

[0066] (8) Chemical copper plating: The pH of the chemical plating solution was adjusted to between 12.0 and 12.2, and heated to 65°C. The activated ceramic substrate was suspended in the plating solution and chemically plated for 2 h under slow stirring. After plating, the substrate was placed in deionized water for ultrasonic treatment for 3 min, and dried in a constant temperature drying oven at 70-80°C for 40 min to obtain fine metallized sample A.

[0067] Example 2

[0068] (1) Preparatory step: Prepare several 15×15 mm alumina ceramic substrates, ultrasonically clean them in alcohol for 3 min, and prepare the patterns to be processed by laser.

[0069] (2) Oil removal treatment: 3 g of sodium hydroxide and 1 g of sodium carbonate were dissolved in 100 mL of deionized water, heated to 60°C, placed in the laser-roughened ceramic substrate, ultrasonicated for 10 min, rinsed with deionized water, and placed in a 70°C oven for 30 min.

[0070] (3) Laser roughening: Import the metallization pattern to be printed into the laser control software, set the laser scanning speed to 200 mm / s, the laser frequency to 100 kHz, the pulse width to 2 μs, and the wavelength to 355 nm, turn on the laser red trace, place the ceramic substrate in the laser red trace area, ensure that the red trace area is in the center of the ceramic substrate, adjust the laser focal length, focus the laser on the upper surface of the ceramic substrate, and start laser laser.

[0071] (4) Preparation of activation solution: Dissolve 1g of copper sulfate pentahydrate in 30mL of deionized water. After fully dissolved, add 70mL of anhydrous ethanol while stirring, heat to 80°C in a water bath, keep warm for 30min, and then filter. Continue to heat the filtered solution to 80°C. Dissolve 0.5% ascorbic acid in 20mL of deionized water to obtain a reducing solution. While stirring, slowly drop the reducing solution into the filtered solution. After reducing for 30min, add 1mL of γ-aminopropyltriethoxysilane (KH550) silane coupling agent, and then add 1mL of γ-glycidyloxypropyltrimethoxysilane (KH560) silane coupling agent 3min later. Continue the reaction for 40min.

[0072] (5) Copper activation treatment: The ceramic substrate was suspended in the activation solution, immersed in ultrasound-assisted solution for 10 min, and allowed to stand for 5 min.

[0073] (6) Cleaning: Rinse the activated ceramic substrate slowly with deionized water to remove the active particles that are not firmly attached to the surface, and absorb the residual moisture with dust-free paper to extend the service life of the plating solution.

[0074] (7) Preparation of chemical plating solution: Weigh 2.56 g of copper sulfate pentahydrate and dissolve it in 160 mL of deionized water. Add 3 g of disodium ethylenediaminetetraacetate, 2.56 g of potassium sodium tartrate, 0.002 g of potassium ferrocyanide and 0.032 g of 2,2'-bipyridine in sequence. After proper stirring, add 2.56 mL of formaldehyde as a reducing agent and adjust the pH to 11 with sodium hydroxide.

[0075] (8) Chemical copper plating: The pH of the chemical plating solution was adjusted to between 12.0 and 12.2, and heated to 65°C. The activated ceramic substrate was suspended in the plating solution and chemically plated for 2 h under slow stirring. After plating, the substrate was placed in deionized water for 3 min under ultrasonication and dried in a constant temperature drying oven at 70-80°C for 40 min to obtain a fine metallized sample B.

[0076] Example 3

[0077] (1) Preparatory step: Prepare several 15×15 mm alumina ceramic substrates, ultrasonically clean them in alcohol for 3 min, and prepare the patterns to be processed by laser.

[0078] (2) Oil removal treatment: 3 g of sodium hydroxide and 1 g of sodium carbonate were dissolved in 100 mL of deionized water, heated to 60°C, placed in the laser-roughened ceramic substrate, ultrasonicated for 10 min, rinsed with deionized water, and placed in a 70°C oven for 30 min.

[0079] (3) Laser roughening: Import the metallization pattern to be printed into the laser control software, set the laser scanning speed to 200 mm / s, the laser frequency to 100 kHz, the pulse width to 2 μs, and the wavelength to 355 nm, turn on the laser red trace, place the ceramic substrate in the laser red trace area, ensure that the red trace area is in the center of the ceramic substrate, adjust the laser focal length, focus the laser on the upper surface of the ceramic substrate, and start laser laser.

[0080] (4) Preparation of activation solution: Dissolve 1g of copper sulfate pentahydrate in 30mL of deionized water. After fully dissolved, add 70mL of anhydrous ethanol while stirring, heat to 80°C in a water bath, keep warm for 30min, and then filter. Continue to heat the filtered solution to 80°C. Dissolve 0.5mL of ascorbic acid in 20mL of deionized water to obtain a reducing solution. While stirring, slowly drop the reducing solution into the filtered solution. After reducing for 30min, add 0.5mL of γ-aminopropyltriethoxysilane (KH550) silane coupling agent, and then add 1.5mL of γ-glycidyloxypropyltrimethoxysilane (KH560) silane coupling agent 3min later. Continue the reaction for 40min.

[0081] (5) Copper activation treatment: The ceramic substrate was suspended in the activation solution, immersed in ultrasound-assisted solution for 10 min, and allowed to stand for 5 min.

[0082] (6) Cleaning: Rinse the activated ceramic substrate slowly with deionized water to remove the active particles that are not firmly attached to the surface, and absorb the residual moisture with dust-free paper to extend the service life of the plating solution.

[0083] (7) Preparation of chemical plating solution: Weigh 2.56 g of copper sulfate pentahydrate and dissolve it in 160 mL of deionized water. Add 3 g of disodium ethylenediaminetetraacetate, 2.56 g of potassium sodium tartrate, 0.002 g of potassium ferrocyanide and 0.032 g of 2,2'-bipyridine in sequence. After proper stirring, add 2.56 mL of formaldehyde as a reducing agent and adjust the pH to 11 with sodium hydroxide.

[0084] (8) Chemical copper plating: The pH of the chemical plating solution was adjusted to between 12.0 and 12.2, and heated to 65°C. The activated ceramic substrate was suspended in the plating solution and chemically plated for 2 h under slow stirring. After plating, the substrate was placed in deionized water for 3 min under ultrasonication and dried in a constant temperature drying oven at 70-80°C for 40 min to obtain a fine metallized sample C.

[0085] Performance Testing:

[0086] The metallized samples prepared in the above embodiments were subjected to a square resistance test using a four-probe square resistance tester produced by Suzhou Tongchuang Electronics Co., Ltd.

[0087] Table 1

[0088] sample A B C Square resistance (mΩ / □) 9.74 60.84 69.70

[0089] It can be seen from Table 1 that the ceramic surface metallization samples can achieve the required electrical interconnection requirements, and with the increase of the γ-aminopropyltriethoxysilane (KH550) content, the square resistance of the formed fine metallization layer becomes larger.

[0090] like Figure 2 As shown, the present invention discloses a method for preparing a fine ceramic circuit board by laser-assisted chemical plating, which can form a fine metallization layer with high resolution on the surface of a ceramic substrate to achieve specific electrical interconnection requirements.

[0091] Example 4

[0092] (1) Preparatory step: Prepare several 15×15 mm silicon nitride ceramic substrates, ultrasonically clean them in alcohol for 3 min, and prepare the patterns to be processed by laser.

[0093] (2) Oil removal treatment: 3 g of sodium hydroxide and 1 g of sodium carbonate were dissolved in 100 mL of deionized water, heated to 60°C, placed in the laser-roughened ceramic substrate, ultrasonicated for 10 min, rinsed with deionized water, and placed in a 70°C oven for 30 min.

[0094] (3) Laser roughening: Import the metallization pattern to be printed into the laser control software, set the laser scanning speed to 200 mm / s, the laser frequency to 100 kHz, the pulse width to 2 μs, and the wavelength to 355 nm, turn on the laser red trace, place the ceramic substrate in the laser red trace area, ensure that the red trace area is in the center of the ceramic substrate, adjust the laser focal length, focus the laser on the upper surface of the ceramic substrate, and start laser laser.

[0095] (4) Preparation of activation solution: Dissolve 1g of copper sulfate pentahydrate in 30mL of deionized water. After fully dissolved, add 70mL of anhydrous ethanol while stirring, heat to 80°C in a water bath, keep warm for 30min, and then filter. Continue to heat the filtered solution to 80°C. Dissolve 0.5% ascorbic acid in 20mL of deionized water to obtain a reducing solution. While stirring, slowly drop the reducing solution into the filtered solution. After reducing for 30min, add 1.5mL of γ-aminopropyltriethoxysilane (KH550) silane coupling agent, and then add 0.5mL of γ-glycidyloxypropyltrimethoxysilane (KH560) silane coupling agent 3min later. Continue the reaction for 40min.

[0096] (5) Copper activation treatment: The ceramic substrate was suspended in the activation solution, immersed in ultrasound-assisted solution for 10 min, and allowed to stand for 5 min.

[0097] (6) Cleaning: Rinse the activated ceramic substrate slowly with deionized water to remove the active particles that are not firmly attached to the surface, and absorb the residual moisture with dust-free paper to extend the service life of the plating solution.

[0098] (7) Preparation of chemical plating solution: Weigh 2.56 g of copper sulfate pentahydrate and dissolve it in 160 mL of deionized water. Add 3 g of disodium ethylenediaminetetraacetate, 2.56 g of potassium sodium tartrate, 0.002 g of potassium ferrocyanide and 0.032 g of 2,2'-bipyridine in sequence. After proper stirring, add 2.56 mL of formaldehyde as a reducing agent and adjust the pH to 11 with sodium hydroxide.

[0099] (8) Chemical copper plating: The pH of the chemical plating solution is adjusted to between 12.0 and 12.2, and heated to 65°C. The activated ceramic substrate is suspended in the plating solution and chemically plated for 2 hours under slow stirring conditions. After plating, it is placed in deionized water for 3 minutes of ultrasonic treatment and dried in a constant temperature drying oven at 70-80°C for 40 minutes. Fine metallized lines can be obtained on the surface of the silicon nitride ceramic substrate.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing fine ceramic circuit boards by laser-assisted chemical plating, It is characterized in that The method comprises the following steps: Step 1: Surface degreasing: Use degreasing liquid to remove oil stains on the surface of the ceramic substrate; Step 2: Laser roughening, using a laser to selectively physically roughen the surface of the ceramic substrate; Step 3: Surface activation, using an activation solution to activate the surface of the ceramic substrate, adsorbing active sites on the laser-roughened surface of the ceramic material, the activation solution contains nano copper particles and a silane coupling agent, and the copper active particles in the activation solution are prepared using an L-ascorbic acid reduction method; the silane coupling agent consists of γ-aminopropyltriethoxysilane and γ-glycidyloxypropyltrimethoxysilane; the preparation method of the activation solution is as follows: dissolve copper sulfate pentahydrate in deionized water, add 2.3 times the volume of deionized water with anhydrous ethanol, heat to 80°C under stirring conditions, keep warm for 30 minutes and then filter, continue to heat the filtered solution to 80°C, add 15-20g / L ascorbic acid under stirring conditions, add 0.02vol% of silane coupling agent after a certain period of reduction, and continue to react for 40 minutes; Step 4: Clean the activated ceramic substrate with deionized water; Step 5: chemical copper plating, using a chemical plating solution to deposit copper on the activated ceramic substrate, wherein the chemical plating solution contains copper sulfate pentahydrate as the main salt, formaldehyde as the reducing agent, disodium ethylenediaminetetraacetate and potassium sodium tartrate as the complexing agents, potassium ferrocyanide and 2,2'-bipyridine as trace additives, and uses magnetic stirring to achieve plating solution convection; the preparation method of the chemical plating solution is: dissolving copper sulfate pentahydrate in deionized water to obtain a copper sulfate solution with a concentration of 16g / L, and adding the complexing agent, potassium ferrocyanide, 2,2'-bipyridine ... A mixture of 18.75 g / L disodium ethylenediaminetetraacetate, 16 g / L sodium potassium tartrate and additives 0.0125 g / L potassium ferrocyanide and 0.2 g / L 2,2'-bipyridine is added with 0.016 vol% formaldehyde as a reducing agent after proper stirring, and the pH is adjusted to 11 with sodium hydroxide; the pH of the chemical plating solution needs to be adjusted to between 12.0 and 12.2 before actual use to ensure that the chemical plating process continues and to prevent the chemical plating reaction from stopping midway due to a decrease in pH value; Step 6: After cleaning and drying, fine metallized lines are obtained on the surface of the ceramic substrate.

2. The method for preparing fine ceramic circuit boards by laser-assisted chemical plating according to claim 1, It is characterized in that In the step 2, the laser roughening step is to use a laser to perform physical roughening on the designed metal pattern. In the specific process: The laser type used is an ultraviolet laser with a power of 5W, a scanning speed of 200mm / s, a frequency of 100KHz, a pulse width of 2μs, and a wavelength of 355nm.

3. The method for preparing fine ceramic circuit boards by laser-assisted chemical plating according to claim 1, It is characterized in that In the step three, the adsorption of the copper active particles is achieved by using silane coupling agents γ-aminopropyltriethoxysilane and γ-glycidyloxypropyltrimethoxysilane.

4. The method for preparing fine ceramic circuit boards by laser-assisted chemical plating according to claim 1, It is characterized in that In step 3, during the adsorption of copper active particles: Ultrasound is needed to assist the adsorption of active sites. The specific operation is: suspend the ceramic substrate in the activation solution for ultrasonic adsorption for 10 minutes and let it stand for 5 minutes.

5. The method for preparing fine ceramic circuit boards by laser-assisted chemical plating according to claim 1, It is characterized in that In step 5, the ceramic substrate is placed in a suspended manner in a chemical plating solution, and the chemical plating environment is: Chemical plating bath temperature: 65°C, slow stirring, chemical plating time: 1-2h.

6. The method for preparing fine ceramic circuit boards by laser-assisted chemical plating according to claim 1, It is characterized in that After the copper activation step on the ceramic substrate, it needs to be rinsed with a slow water flow to remove unreliable copper nanoparticles and extend the service life of the plating solution.

7. The method for preparing fine ceramic circuit boards by laser-assisted chemical plating according to claim 1, It is characterized in that In the steps of degreasing the ceramic substrate: The degreasing liquid formula is 30g / LNaOH, 10g / LNa 2 CO 3 , the temperature is 60℃ and the processing time is 10min.

Images