Processing method for copper-clad ceramic substrate
By employing a layered, progressive micro-hole processing method and optimizing laser parameters, the problems of cracking and edge chipping during picosecond laser processing of alumina ceramic substrates were solved, enabling the production of high-quality copper-clad ceramic substrates.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-02
- Publication Date
- 2026-05-01
AI Technical Summary
Existing technologies are prone to cracking and edge chipping when processing alumina ceramic substrates with picosecond lasers. This is mainly due to improper delamination control, improper laser parameters, and oxidation reactions and volume expansion stress caused by the lack of inert gas.
A layered progressive micropore processing method is adopted, in which picosecond laser is used to process alumina ceramic substrate in layers. By combining the use of inert gas and optimizing laser parameters, an inlet layer, an intermediate layer and an outlet layer are set. Small spot size and long focal depth lens are used to control the uniformity of energy density and reduce oxidation reaction and stress generation.
It effectively prevents cracks and edge chipping in alumina ceramic substrates during the drilling process, improves the substrate's density, toughness, and mechanical strength, and ensures processing quality.
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Figure CN121949004A_ABST
Abstract
Description
A processing method for copper-clad ceramic substrates Technical Field
[0001] This invention relates to the field of copper-clad ceramic substrate processing technology, specifically a processing method for copper-clad ceramic substrates. Background Technology
[0002] Picosecond lasers are a laser technology that uses ultrashort pulses to excite laser beams. They are commonly used in high-end electronic packaging and ceramic substrates for micro-hole processing of brittle materials such as alumina. However, due to material and processing techniques, cracks and chipping often occur at the edges of the micro-holes. The reasons are as follows: During picosecond laser processing, on the one hand, the lack of layer control leads to uneven stress release, resulting in cracks and chipping; on the other hand, improper laser parameter settings result in a large heat-affected zone, leading to cracks and chipping; secondly, the failure to use inert gas and suppress oxidation reactions leads to volume expansion stress, resulting in cracks and chipping.
[0003] To address the aforementioned problems and prevent cracks and chipping of alumina materials during processing, this invention provides a processing method for copper-clad ceramic substrates. Summary of the Invention
[0004] The purpose of this invention is to provide a processing method for copper-clad ceramic substrates to solve the problems raised in the prior art.
[0005] To achieve the above objectives, the present invention provides the following technical solution: Step 1: Take an alumina ceramic substrate, clean it, dry it, perform plasma treatment, and vacuum sputtering to obtain a sputtered copper-clad ceramic substrate; take the sputtered copper-clad ceramic substrate, degrease it, pickle it, electroplate it with copper, clean it, dry it, perform photolithography, electroplating thickening, remove the resist, and etch it to obtain a pre-treated copper-clad ceramic substrate; Step 2: Take the pre-treated copper-clad ceramic substrate, introduce nitrogen gas, and use a picosecond laser to perform layered progressive micro-hole processing on the exposed alumina ceramic substrate of the pre-treated copper-clad ceramic substrate to form micro-holes, which are divided into an entrance layer, an intermediate layer, and an exit layer from top to bottom; Step 3: Adjust the single-pulse energy and frequency parameters of the picosecond laser to drill holes in the entrance layer; Step 4: Adjust the single-pulse energy and frequency parameters of the picosecond laser to drill holes in the intermediate layer; Step 5: Adjust the single-pulse energy and frequency parameters of the picosecond laser to drill holes in the exit layer to obtain a copper-clad ceramic substrate.
[0006] In a more optimized configuration, the thickness of the alumina ceramic substrate is equal to the number of micropore layers multiplied by the thickness of each layer. The thickness of the alumina ceramic substrate is 0.1-2 mm, the thickness of each layer is 5-20 µm, and the ratio of the number of inlet layer, intermediate layer, and outlet layer is (3-4):(1-2):(0.3-0.7).
[0007] A more optimized picosecond laser process involves using a spot size and a long focal depth lens, with a spot diameter of 5-15µm and a pulse width of 10-50ps.
[0008] In a more optimized configuration, the single-pulse energy of the inlet and outlet layers is 5-12µJ, and the frequency of the inlet layer is 100-200kHz.
[0009] In a more optimized configuration, the single-pulse energy of the intermediate layer is 15-30µJ, and the frequency of the intermediate layer is 100-150kHz.
[0010] A more optimized nitrogen gas flow rate is 5-15 L / min.
[0011] A more optimized method for preparing alumina ceramic substrates is as follows: Anhydrous ethanol, isopropanol, and n-butanol are mixed evenly to obtain a mixed solvent; the mixed powder, mixed solvent, dispersant, and zirconia grinding balls are ball-milled; polyvinyl butyral and dibutyl phthalate are added, and the mixture is ball-milled and cast to obtain a ceramic green sheet; the ceramic green sheet is cut, left to stand, demolded, vacuum-sealed, and cold isostatically pressed; it is then removed, degreased, sintered, and cooled under a nitrogen atmosphere to obtain an alumina ceramic substrate.
[0012] A more optimized method for preparing the mixed powder is as follows: Take a core-shell structured carbon nanotube-zirconia precursor, heat it to 500-700℃ under an argon atmosphere at a heating rate of 4-6℃ / min, and calcine it for 1-2 hours to obtain toughened powder; Take alumina powder, toughened powder, sintering aid, add anhydrous ethanol and zirconia grinding balls, ball mill at a speed of 300-400 rpm for 5-7 hours, rotary evaporate at a temperature of 55-65℃, and sieve to obtain the mixed powder.
[0013] A more optimized method for preparing the core-shell structured carbon nanotube-zirconia precursor is as follows: Zirconia oxychloride is added to deionized water and mixed evenly to obtain a zirconium oxychloride solution; concentrated nitric acid and concentrated sulfuric acid are mixed evenly to obtain a solvent; carbon nanotubes are added to the solvent, sonicated, washed, added to deionized water, sonicated, hexadecyltrimethylammonium bromide is added, magnetically stirred, added to the zirconium oxychloride solution, mixed evenly, and the pH value is adjusted to 9-11 using ammonia water. The reaction is carried out at a temperature of 140-160℃ for 14-16 hours, cooled, washed, impurities removed, and dried to obtain the core-shell structured carbon nanotube-zirconia precursor.
[0014] A more optimized method for preparing the sintering aid is as follows: take alumina sol, silica sol, yttrium hexahydrate, and magnesium nitrate hexahydrate, dry them, grind them, shape them, remove the binder at 400-600℃ for 5-7 hours, and sinter at 1500-1600℃ for 3-5 hours to obtain the sintering aid.
[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The preparation of sintering aids, including alumina sol, silica sol, yttrium hexahydrate, and magnesium nitrate hexahydrate, involves debinding and sintering. Yttrium hexahydrate and magnesium nitrate hexahydrate decompose to form yttrium oxide and magnesium oxide, which, together with alumina and silica, form a eutectic mixture containing alumina, silica, yttrium oxide, and magnesium oxide. Under high-temperature conditions, this reduces the sintering temperature, promotes the sintering of alumina powder, inhibits grain growth, suppresses porosity, and improves the density, toughness, and mechanical strength of the alumina ceramic substrate.
[0016] 2. Preparation of toughening filler: Carbon nanotubes are acidified to introduce hydroxyl and carboxyl groups on their surface, which then combine with zirconium ions in a zirconium oxychloride solution. Under alkaline conditions, zirconium oxychloride hydrolyzes to form zirconium hydroxide. Zirconium hydroxide is dehydrated during calcination to form zirconium oxide. Hexadecyltrimethylammonium bromide is used as a surfactant to construct a toughening powder with a carbon nanotube-zirconia core-shell structure. Carbon nanotubes have excellent strength and toughness, and zirconium oxide provides synergistic toughening through a phase transformation toughening mechanism, preventing cracks from forming during the drilling process.
[0017] 3. Picosecond laser is used to perform layered progressive drilling on the pre-treated copper-clad ceramic substrate. An entry layer, intermediate layer, and exit layer are set up. A smaller diameter spot and a long focal depth lens are selected to ensure uniform energy density. Under an inert atmosphere, the volume expansion stress caused by oxidation reaction is reduced. At the entry layer, low energy and high frequency are used to reduce edge chipping at the entry. In the intermediate layer, the single pulse energy is gradually increased and a stable frequency is maintained to ensure that the material is removed uniformly. At the exit layer, the energy is reduced to avoid cracking caused by the stress generated at the moment of material piercing. Attached Figure Description
[0018] Figure 1 is a diagram of a circular hole with cracked edges and chipped porcelain in Comparative Example 1 of the present invention; Figure 2 is a diagram of an irregular hole with cracked edges and chipped porcelain in Comparative Example 1 of the present invention; Figure 3 is a diagram of a circular hole without cracked edges and chipped porcelain in Embodiment 3 of the present invention; Figure 4 is a diagram of an irregular hole without cracked edges and chipped porcelain in Embodiment 3 of the present invention. Detailed Implementation
[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.
[0020] The sources and types of substances involved in this invention are not specifically limited. Exemplary examples include: alumina sol (item number PT-L128) provided by Hefei Yihao New Material Technology Co., Ltd.; silica sol (item number ZTL-AN-25) provided by Yangzhou Zhongtianli New Material Co., Ltd.; yttrium nitrate hexahydrate (item number 04-20-12) provided by Shandong Desheng New Material Co., Ltd.; magnesium nitrate hexahydrate (item number 14137) provided by Shenzhen Tiancheng Chemical Co., Ltd.; and zirconium oxychloride (item number js2024112909). The following products were provided: carbon nanotubes (item number T19281) and hexadecyltrimethylammonium bromide (item number S15001) from Shanghai Yuanye Biotechnology Co., Ltd.; alumina powder (item number 035) from Shanghai Yingcheng New Materials Co., Ltd.; dispersant (item number BYK110) from Dongguan Rentong Chemical Co., Ltd.; zirconia grinding balls (item number RS955) from Zibo Rongsheng Ceramics Technology Co., Ltd.; polyvinyl butyral (item number Butvar B98) from Guangzhou Daixun Trading Co., Ltd.; and dibutyl phthalate (item number 003) from Jinan Dehou Chemical Co., Ltd.
[0021] Example 1: A processing method for copper-clad ceramic substrates; Step 1: Preparation of sintering aid: Take 50g alumina sol, 30g silica sol, 15g yttrium nitrate hexahydrate, and 5g magnesium nitrate hexahydrate, dry, grind, and shape. Remove the binder at 500℃ for 6 hours, and sinter at 1550℃ for 4 hours to obtain the sintering aid; Step 2: Toughening powder S1: Take 1g zirconium oxychloride and add it to 9mL of deionized water, mix evenly to obtain a zirconium oxychloride solution; Take concentrated nitric acid and concentrated sulfuric acid at a volume ratio of 1:3, mix evenly to obtain a solvent; Take 1g carbon nanotubes, add 100mL of solvent, sonicate at 75℃ for 3 hours, clean, and add deionized water... In deionized water, the mixture was sonicated for 30 min, and 0.5 g of hexadecyltrimethylammonium bromide was added. The mixture was magnetically stirred for 2 h at 60 °C, then added to 35 mL of zirconium oxychloride solution and mixed thoroughly. The pH was adjusted to 10 using ammonia water, and the mixture was reacted at 150 °C for 15 h. After cooling, washing, removing impurities, and drying, a core-shell carbon nanotube-zirconia precursor was obtained. S2: The core-shell carbon nanotube-zirconia precursor was heated to 600 °C at a heating rate of 5 °C / min under an argon atmosphere and calcined for 1.5 h to obtain toughened powder. Step 3: Casting and Molding S1: 92 g of alumina powder, 3 g of toughening powder, and 5 g of sintering aid were added to 145 mL of alumina powder. S1: A mixture of 195g of zirconia grinding balls and aqueous ethanol was ball-milled at 350 rpm for 6 hours. The mixture was then rotary evaporated at 60℃ and sieved to obtain a mixed powder. S2: 20mL of anhydrous ethanol, 20mL of isopropanol, and 10mL of n-butanol were mixed thoroughly to obtain a mixed solvent. 100g of the mixed powder, 105mL of the mixed solvent, 1.2g of dispersant, and 200g of zirconia grinding balls were ball-milled at 350 rpm for 4 hours. 8g of polyvinyl butyral and 2g of dibutyl phthalate were added, and the mixture was ball-milled at 350 rpm for 4 hours, controlling the scraper height at 300μm and the substrate speed at 0.2m / min. The mixture was then dried at 45℃. Under the following conditions, the ceramic green sheet is obtained by tape casting; Step 4: Preparation of alumina ceramic substrate. Take the ceramic green sheet, cut it, and let it stand for 60 min at 65℃, then stand for 2 min at 10 MPa. Remove the film, vacuum seal it, pressurize it to 200 MPa at a pressurization rate of 40 MPa / min, and let it stand for 5 min at 200 MPa. Take it out, degrease it under a nitrogen atmosphere, heat it to 800℃ at a heating rate of 10℃ / min, then heat it to 1600℃ at a heating rate of 5℃ / min, and sinter it for 2 h at 1600℃. Cool it to obtain an alumina ceramic substrate with a thickness of 0.5mm; Take an alumina ceramic substrate, clean, dry, plasma treat, vacuum sputter, to obtain a sputtered copper-clad ceramic substrate; Step 5: Layered progressive drilling S1: Take the sputtered copper-clad ceramic substrate, degrease, pickle, electroplat copper, clean, dry, photolithography, electroplating thickening, remove resist, etch, to obtain a pre-treated copper-clad ceramic substrate; S2: Take the pre-treated copper-clad ceramic substrate, under a gas flow rate of 10L / min, introduce nitrogen gas, and use a picosecond laser to perform layered progressive micro-hole processing on the exposed alumina ceramic substrate of the pre-treated copper-clad ceramic substrate to form micro-holes, the micro-holes are divided into an entrance layer, an intermediate layer, and a... The exit layer is constructed by controlling the number of microvia layers to be 50, with each microvia layer having a thickness of 10 μm. The layer ratio of the entry layer, intermediate layer, and exit layer is 3.5:1.5:0.5, the pulse width is 30 ps, and a long focal depth lens with a spot diameter of 10 µm is used. The single-pulse energy of the picosecond laser is adjusted to 8 μJ and the frequency to 120 kHz for drilling the entry layer. The single-pulse energy of the picosecond laser is adjusted to 20 μJ and the frequency to 100 kHz for drilling the intermediate layer. Finally, the single-pulse energy of the picosecond laser is adjusted to 8 μJ and the frequency to 120 kHz for drilling the exit layer, resulting in a copper-clad ceramic substrate.
[0022] Example 2: The alumina ceramic substrate thickness is 1.0 mm, the gas flow rate is controlled at 12 L / min, the number of micropore layers is 67, the thickness of each micropore layer is 15 μm, and the pulse width is 50 ps; the single pulse energy of the picosecond laser is adjusted to 10 μJ and the frequency is 150 kHz to drill holes in the inlet layer; the single pulse energy of the picosecond laser is adjusted to 25 μJ and the frequency is 100 kHz to drill holes in the middle layer; the single pulse energy of the picosecond laser is adjusted to 10 μJ and the frequency is 150 kHz to drill holes in the outlet layer, and the rest is the same as in Example 1; Example 3: The alumina ceramic substrate thickness is 0.3 mm, the gas flow rate is controlled at 8 L / min, the number of micropore layers is 60, the thickness of each micropore layer is 5 μm, and the pulse width is 20 ps. PS: Adjust the single pulse energy of the picosecond laser to 5 μJ and the frequency to 200 kHz to drill holes in the inlet layer; adjust the single pulse energy of the picosecond laser to 15 μJ and the frequency to 150 kHz to drill holes in the intermediate layer; adjust the single pulse energy of the picosecond laser to 5 μJ and the frequency to 200 kHz to drill holes in the outlet layer, and refer to Example 1 for the rest; Example 4: The alumina ceramic substrate thickness is 0.8 mm, the gas flow rate is controlled at 15 L / min, the number of micropore layers is 67, the thickness of each micropore layer is 12 μm, and the pulse width is 40 ps; adjust the single pulse energy of the picosecond laser to 9 μJ and the frequency to 130 kHz to drill holes in the inlet layer; adjust the single pulse energy of the picosecond laser to 22 μJ and the frequency to 110 kHz. Hz, drilling holes in the intermediate layer; adjusting the single pulse energy of the picosecond laser to 9μJ and the frequency to 130kHz, drilling holes in the exit layer, the rest is the same as in Example 1; Example 5: The alumina ceramic substrate thickness is 1.2mm, the gas flow rate is controlled at 10L / min, the number of micropore layers is 60, the thickness of each micropore layer is 20μm, and the pulse width is 50ps; adjusting the single pulse energy of the picosecond laser to 12μJ and the frequency to 100kHz, drilling holes in the inlet layer; adjusting the single pulse energy of the picosecond laser to 30μJ and the frequency to 90kHz, drilling holes in the intermediate layer; adjusting the single pulse energy of the picosecond laser to 12μJ and the frequency to 100kHz, drilling holes in the exit layer, the rest is the same as in Example 1; Comparative Example 1: The layered progressive drilling method is not used; the rest is as described in Example 2. Step 1: Preparation of sintering aid: Take 50g of alumina sol, 30g of silica sol, 15g of yttrium hexahydrate, and 5g of magnesium nitrate hexahydrate. Dry, grind, and shape. Remove the binder at 500℃ for 6 hours, and sinter at 1550℃ for 4 hours to obtain the sintering aid. Step 2: Toughening powder S1: Take 1g of zirconium oxychloride and add it to 9mL of deionized water. Mix well to obtain a zirconium oxychloride solution. Take concentrated nitric acid and concentrated sulfuric acid at a volume ratio of 1:3 and mix well to obtain a solvent. Take 1g of carbon nanotubes and add them to 100mL of solvent. Sonicate at 75℃ for 3 hours, clean, add to deionized water, sonicate for 30 minutes, and add 0.5g of hexadecyltrimethylammonium bromide was magnetically stirred at 60℃ for 2 hours, then added to 35mL of zirconium oxychloride solution and mixed thoroughly. The pH was adjusted to 10 with ammonia water, and the mixture was reacted at 150℃ for 15 hours. After cooling, washing, removing impurities, and drying, a core-shell carbon nanotube-zirconia precursor was obtained. S2: The core-shell carbon nanotube-zirconia precursor was heated to 600℃ at a rate of 5℃ / min under an argon atmosphere and calcined for 1.5 hours to obtain toughened powder. Step 3: Casting and Molding S1: 92g of alumina powder, 3g of toughening powder, and 5g of sintering aid were added to 145mL of anhydrous ethanol and 195g of zirconium oxide grinding balls. The mixture was then calcined at a speed of 350 ... S1: Ball milling for 6 hours at 0 rpm, followed by rotary evaporation and sieving at 60℃ to obtain a mixed powder; S2: Take 20 mL of anhydrous ethanol, 20 mL of isopropanol, and 10 mL of n-butanol, mix them evenly to obtain a mixed solvent; Take 100 g of the mixed powder, 105 mL of the mixed solvent, 1.2 g of dispersant, and 200 g of zirconia grinding balls, and ball mill for 4 hours at 350 rpm. Add 8 g of polyvinyl butyral and 2 g of dibutyl phthalate, and ball mill for 4 hours at 350 rpm, controlling the scraper height to 300 μm and the substrate speed to 0.2 m / min. Then, cast the mixture at a drying temperature of 45℃ to obtain a ceramic green sheet; Step 4 Preparation of alumina ceramic substrate: A ceramic green sheet was taken, cut, and allowed to stand for 60 minutes at 65℃, followed by 2 minutes at 10 MPa. The substrate was then demolded, vacuum-sealed, and pressurized to 200 MPa at a rate of 40 MPa / min. It was then allowed to stand for 5 minutes at 200 MPa. The substrate was then removed, degreased under a nitrogen atmosphere, and heated to 800℃ at a rate of 10℃ / min, followed by 1600℃ at a rate of 5℃ / min. Sintering was carried out at 1600℃ for 2 hours, followed by cooling to obtain an alumina ceramic substrate with a thickness of 1.0 mm. The alumina ceramic substrate was then cleaned, dried, and subjected to plasma treatment. Step 5: Layered progressive drilling S1: Take the sputtered copper-clad ceramic substrate, degrease, pickle, electroplate copper, clean, dry, photolithography, electroplate thickening, remove resist, and etch to obtain a pre-treated copper-clad ceramic substrate; S2: Take the pre-treated copper-clad ceramic substrate, under a gas flow rate of 12L / min, introduce nitrogen gas, and use a picosecond laser to process micro-holes in the exposed alumina ceramic substrate of the pre-treated copper-clad ceramic substrate to form micro-holes. Control the pulse width to 50ps, use a spot size and long focal depth lens, and a spot diameter of 10µm; adjust the single pulse energy of the picosecond laser to 25μJ and the frequency to 100kHz to perform drilling to obtain the copper-clad ceramic substrate.
[0023] Comparative Example 2: No sintering aids were added; all other steps are the same as in Example 2. Step 1: Toughening Powder S1: 1g of zirconium oxychloride was added to 9mL of deionized water and mixed evenly to obtain a zirconium oxychloride solution. Concentrated nitric acid and concentrated sulfuric acid were mixed evenly at a volume ratio of 1:3 to obtain a solvent. 1g of carbon nanotubes was added to 100mL of solvent and sonicated at 75°C for 3 hours. After cleaning, the mixture was added to deionized water and sonicated for 30 minutes. 0.5g of cetyltrimethylammonium bromide was added and magnetically stirred at 60°C for 2 hours. The mixture was then added to 35mL of the zirconium oxychloride solution and mixed evenly. The pH was adjusted using ammonia. The reaction was carried out at 150℃ for 15 hours, followed by cooling, washing, impurity removal, and drying to obtain a core-shell carbon nanotube-zirconia precursor. S2: The core-shell carbon nanotube-zirconia precursor was heated to 600℃ at a rate of 5℃ / min under an argon atmosphere and calcined for 1.5 hours to obtain toughened powder. Step 2: Casting and Molding S1: 92g of alumina powder, 3g of toughening powder, and 5g of sintering aid were added to 145mL of anhydrous ethanol and 195g of zirconia grinding balls. The mixture was ball-milled at 350rpm for 6 hours, then rotary evaporated at 60℃ and sieved. A mixed powder was obtained; S2: 20 mL of anhydrous ethanol, 20 mL of isopropanol, and 10 mL of n-butanol were mixed evenly to obtain a mixed solvent; 100 g of the mixed powder, 105 mL of the mixed solvent, 1.2 g of dispersant, and 200 g of zirconia grinding balls were ball-milled at 350 rpm for 4 h; 8 g of polyvinyl butyral and 2 g of dibutyl phthalate were added, and the mixture was ball-milled at 350 rpm for 4 h, with the scraper height controlled at 300 μm and the substrate speed at 0.2 m / min; the mixture was then cast into ceramic green sheets at a drying temperature of 45℃; Step 3: Preparation of oxygen Alumina ceramic substrate is prepared by taking a ceramic green sheet, cutting it, and letting it stand for 60 minutes at 65℃, then for 2 minutes at 10MPa. After demolding and vacuum sealing, the pressure is increased to 200MPa at a rate of 40MPa / min, and then left to stand for 5 minutes at 200MPa. The substrate is then removed, degreased under a nitrogen atmosphere, and heated to 800℃ at a rate of 10℃ / min, then to 1600℃ at a rate of 5℃ / min. It is then sintered at 1600℃ for 2 hours and cooled to obtain an alumina ceramic substrate with a thickness of 1 mm.0mm; Take an alumina ceramic substrate, clean, dry, plasma treat, vacuum sputter, to obtain a sputtered copper-clad ceramic substrate; Step 4: Layered progressive drilling S1: Take the sputtered copper-clad ceramic substrate, degrease, pickle, electroplat copper, clean, dry, photolithography, electroplating thickening, remove resist, etch, to obtain a pre-treated copper-clad ceramic substrate; S2: Take the pre-treated copper-clad ceramic substrate, under a gas flow rate of 12L / min, introduce nitrogen gas, and use a picosecond laser to perform layered progressive micro-hole processing on the exposed alumina ceramic substrate of the pre-treated copper-clad ceramic substrate to form micro-holes. The micro-holes are divided into an inlet layer, an intermediate layer, and an outlet layer from top to bottom. The entry layer was constructed by controlling the number of microvia layers to be 67, with each microvia layer having a thickness of 15 μm. The layer ratio of the entry layer, intermediate layer, and exit layer was 3.5:1.5:0.5, with a pulse width of 50 ps. A long focal depth lens with a spot diameter of 10 µm was used. The single-pulse energy of the picosecond laser was adjusted to 10 μJ and the frequency to 150 kHz to drill holes in the entry layer. The single-pulse energy of the picosecond laser was adjusted to 25 μJ and the frequency to 100 kHz to drill holes in the intermediate layer. The single-pulse energy of the picosecond laser was adjusted to 10 μJ and the frequency to 150 kHz to drill holes in the exit layer, resulting in a copper-clad ceramic substrate.
[0024] Comparative Example 3: Zirconium oxychloride was not added; all other steps are the same as in Example 2. Step 1: Preparation of sintering aid: Take 50g of alumina sol, 30g of silica sol, 15g of yttrium hexahydrate, and 5g of magnesium nitrate hexahydrate. Dry, grind, and shape. Remove the binder at 500℃ for 6 hours, and sinter at 1550℃ for 4 hours to obtain the sintering aid. Step 2: Toughening powder S1: Take concentrated nitric acid and concentrated sulfuric acid at a volume ratio of 1:3, mix evenly to obtain a solvent. Take 1g of carbon nanotubes, add 100mL of solvent, sonicate at 75℃ for 3 hours, wash, add to deionized water, sonicate for 30 minutes, and add 0. 5g of hexadecyltrimethylammonium bromide was magnetically stirred at 60℃ for 2 hours, then added to 35mL of deionized water and mixed thoroughly. The pH was adjusted to 10 using ammonia water, and the mixture was reacted at 150℃ for 15 hours. After cooling, washing, removing impurities, and drying, the precursor was obtained. S2: The precursor was heated to 600℃ at a rate of 5℃ / min under an argon atmosphere and calcined for 1.5 hours to obtain toughened powder. Step 3: Casting and Molding S1: 92g of alumina powder, 3g of toughening powder, and 5g of sintering aid were added to 145mL of anhydrous ethanol and 195g of zirconia grinding balls. The mixture was then rolled at 350rpm. Grind for 6 hours, then rotary evaporate at 60℃, and sieve to obtain a mixed powder; S2: Take 20mL of anhydrous ethanol, 20mL of isopropanol, and 10mL of n-butanol, mix them evenly to obtain a mixed solvent; Take 100g of the mixed powder, 105mL of the mixed solvent, 1.2g of dispersant, and 200g of zirconia grinding balls, and ball mill at 350rpm for 4 hours. Add 8g of polyvinyl butyral and 2g of dibutyl phthalate, and ball mill at 350rpm for 4 hours. Control the scraper height to be 300μm and the substrate speed to be 0.2m / min. Under drying conditions of 45℃, cast and mold to obtain ceramic raw material. Step 4: Preparation of alumina ceramic substrate. Take a ceramic green sheet, cut it, and let it stand for 60 minutes at 65℃, then stand for 2 minutes at 10MPa. Remove the film, vacuum seal it, pressurize it to 200MPa at a rate of 40MPa / min, and let it stand for 5 minutes at 200MPa. Take it out, degrease it under a nitrogen atmosphere, heat it to 800℃ at a rate of 10℃ / min, then heat it to 1600℃ at a rate of 5℃ / min, and sinter it at 1600℃ for 2 hours. Cool it to obtain an alumina ceramic substrate with a thickness of 1 mm.0mm; Take an alumina ceramic substrate, clean, dry, plasma treat, vacuum sputter, to obtain a sputtered copper-clad ceramic substrate; Step 5: Layered progressive drilling S1: Take the sputtered copper-clad ceramic substrate, degrease, pickle, electroplat copper, clean, dry, photolithography, electroplating thickening, remove resist, etch, to obtain a pre-treated copper-clad ceramic substrate; S2: Take the pre-treated copper-clad ceramic substrate, under a gas flow rate of 12L / min, introduce nitrogen gas, and use a picosecond laser to perform layered progressive micro-hole processing on the exposed alumina ceramic substrate of the pre-treated copper-clad ceramic substrate to form micro-holes. The micro-holes are divided into an inlet layer, an intermediate layer, and an outlet layer from top to bottom. The entry layer was constructed by controlling the number of microvia layers to be 67, with each microvia layer having a thickness of 15 μm. The layer ratio of the entry layer, intermediate layer, and exit layer was 3.5:1.5:0.5, with a pulse width of 50 ps. A long focal depth lens with a spot diameter of 10 µm was used. The single-pulse energy of the picosecond laser was adjusted to 10 μJ and the frequency to 150 kHz to drill holes in the entry layer. The single-pulse energy of the picosecond laser was adjusted to 25 μJ and the frequency to 100 kHz to drill holes in the intermediate layer. The single-pulse energy of the picosecond laser was adjusted to 10 μJ and the frequency to 150 kHz to drill holes in the exit layer, resulting in a copper-clad ceramic substrate.
[0025] Experiment: The alumina ceramic substrates and copper-clad ceramic substrates prepared in Examples 1-5 and Comparative Examples 1-3 were tested; (1) Bending strength was tested in accordance with GB / T6569-2006 Test Method for Bending Strength of Fine Ceramics. The three-point method was used to test the bending strength. The sample size was 3mm×4mm×36mm, the span was 30mm, and the loading speed was 0.5mm / min; (2) Fracture toughness was tested by indentation method. The Vickers hardness tester was used. The loading force was 10kg and the holding time was 10s. The diagonal length of the indentation and the crack length were measured, and the hardness and fracture toughness were calculated; (3) Sensory evaluation was performed on the copper-clad ceramic substrates prepared in Examples 1-5 and Comparative Examples 1-3. The width of the chipped ceramic at the hole edge was measured, and the presence or absence of cracks was observed; The above experiments were completed, and the experimental results are shown in Table 1-2 below: Table 1
[0026] Table 2
[0027] Conclusion: The alumina ceramic substrates prepared in Examples 1-5 have high bending strength and fracture toughness, small chipping width at the hole edge, no cracks after drilling, and excellent toughness, making them less prone to cracking. The alumina ceramic substrates prepared in Comparative Examples 1-3 have low bending strength and fracture toughness, large chipping width at the hole edge, cracks after drilling, poor toughness, and are prone to cracking.
[0028] Comparative analysis of Comparative Example 1 (which does not employ layered progressive drilling) and Example 2 reveals that layered progressive drilling of the pre-treated copper-clad ceramic substrate using picosecond lasers, with an entry layer, intermediate layer, and exit layer, employs a smaller diameter spot and a long focal depth lens to ensure uniform energy density. Under an inert atmosphere, this reduces volume expansion stress caused by oxidation. In the entry layer, low energy and high frequency are used to reduce edge chipping. In the intermediate layer, the single-pulse energy is gradually increased while maintaining a stable frequency to ensure uniform material removal. In the exit layer, the energy is reduced to avoid cracking caused by the stress generated during material penetration.
[0029] Comparative analysis of Comparative Example 2 (without sintering aids) and Example 2 shows that, through debinding and sintering, alumina sol, silica sol, yttrium hexahydrate, and magnesium nitrate hexahydrate decompose to form yttrium oxide and magnesium oxide, which, together with alumina and silica, form a eutectic containing alumina, silica, yttrium oxide, and magnesium oxide. Under high-temperature conditions, this lowers the sintering temperature, promotes the sintering of alumina powder, inhibits grain growth, suppresses porosity, and improves the density, toughness, and mechanical strength of the alumina ceramic substrate.
[0030] Comparative analysis of Comparative Example 3 (without zirconium oxychloride) and Example 2 shows that carbon nanotubes, through acidification treatment, introduce hydroxyl and carboxyl groups on their surface, which combine with zirconium ions in the zirconium oxychloride solution. Under alkaline conditions, zirconium oxychloride hydrolyzes to form zirconium hydroxide. During calcination, zirconium hydroxide dehydrates to form zirconium oxide. Hexadecyltrimethylammonium bromide is used as a surfactant to construct a toughened powder with a carbon nanotube-zirconia core-shell structure. Zirconia is toughened through a phase transformation toughening mechanism to prevent cracks from forming during the drilling process.
[0031] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.
Claims
1. A processing method for copper-clad ceramic substrates, characterized in that: Including the following Steps: Step 1: Take an alumina ceramic substrate, clean, dry, perform plasma treatment, and vacuum sputter to obtain a sputtered copper-clad ceramic substrate; take the sputtered copper-clad ceramic substrate, degrease, pickle, electroplate copper, clean, dry, perform photolithography, electroplate thickening, remove resist, and etch to obtain a pre-treated copper-clad ceramic substrate; Step 2: Take the pre-treated copper-clad ceramic substrate, introduce nitrogen gas, and use a picosecond laser to perform layered progressive micro-hole processing on the exposed alumina ceramic substrate of the pre-treated copper-clad ceramic substrate to form micro-holes, which are divided into an entrance layer, an intermediate layer, and an exit layer from top to bottom; Step 3: Adjust the single-pulse energy and frequency parameters of the picosecond laser to drill holes in the entrance layer; Step 4: Adjust the single-pulse energy and frequency parameters of the picosecond laser to drill holes in the intermediate layer; Step 5: Adjust the single-pulse energy and frequency parameters of the picosecond laser to drill holes in the exit layer to obtain a copper-clad ceramic substrate.
2. The processing method for copper-clad ceramic substrates according to claim 1, characterized in that: The thickness of the alumina ceramic substrate is equal to the number of micropore layers × the thickness of each layer. The thickness of the alumina ceramic substrate is 0.1-2 mm, the thickness of each layer is 5-20 µm, and the ratio of the number of inlet layer, intermediate layer and outlet layer is (3-4):(1-2):(0.3-0.7).
3. The processing method for copper-clad ceramic substrates according to claim 1, characterized in that: The picosecond laser process involves using a spot size and a long focal depth lens, with a spot diameter of 5-15µm and a pulse width of 10-50ps.
4. The processing method for copper-clad ceramic substrates according to claim 1, characterized in that: The single-pulse energy of the inlet and outlet layers is 5-12µJ, and the frequency of the inlet and outlet layers is 100-200kHz.
5. A processing method for copper-clad ceramic substrates according to claim 1, characterized in that: The single-pulse energy of the intermediate layer is 15-30µJ, and the frequency of the intermediate layer is 100-150kHz.
6. The processing method for copper-clad ceramic substrates according to claim 1, characterized in that: The nitrogen gas flow rate is 5-15 L / min.
7. A processing method for copper-clad ceramic substrates according to claim 1, characterized in that: The preparation method of the alumina ceramic substrate is as follows: anhydrous ethanol, isopropanol, and n-butanol are mixed evenly to obtain a mixed solvent; the mixed powder, mixed solvent, dispersant, and zirconia grinding balls are ball-milled; polyvinyl butyral and dibutyl phthalate are added, and the mixture is ball-milled and cast to obtain a ceramic green sheet; the ceramic green sheet is cut, left to stand, demolded, vacuum-sealed, and cold isostatically pressed; it is then removed, degreased, sintered, and cooled under a nitrogen atmosphere to obtain the alumina ceramic substrate.
8. A processing method for copper-clad ceramic substrates according to claim 7, characterized in that: The preparation method of the mixed powder is as follows: take the core-shell structured carbon nanotube-zirconia precursor, heat it to 500-700℃ under argon atmosphere at a heating rate of 4-6℃ / min, and calcine it for 1-2 hours to obtain toughened powder; take alumina powder, toughened powder, sintering aid, add anhydrous ethanol and zirconia grinding balls, ball mill at a speed of 300-400 rpm for 5-7 hours, rotary evaporate at a temperature of 55-65℃, and sieve to obtain the mixed powder.
9. A processing method for copper-clad ceramic substrates according to claim 8, characterized in that: The preparation method of the core-shell structured carbon nanotube-zirconia precursor is as follows: Zirconia oxychloride is added to deionized water and mixed evenly to obtain a zirconium oxychloride solution; concentrated nitric acid and concentrated sulfuric acid are mixed evenly to obtain a solvent; carbon nanotubes are added to the solvent, sonicated, washed, added to deionized water, sonicated, hexadecyltrimethylammonium bromide is added, magnetically stirred, added to the zirconium oxychloride solution, mixed evenly, the pH value is adjusted to 9-11 with ammonia water, and the reaction is carried out at a temperature of 140-160℃ for 14-16 hours. After cooling, washing, removing impurities, and drying, the core-shell structured carbon nanotube-zirconia precursor is obtained.
10. A processing method for copper-clad ceramic substrates according to claim 8, characterized in that: The preparation method of the sintering aid is as follows: take alumina sol, silica sol, yttrium hexahydrate, and magnesium nitrate hexahydrate, dry them, grind them, shape them, remove the binder at a temperature of 400-600℃ for 5-7 hours, and sinter at a temperature of 1500-1600℃ for 3-5 hours to obtain the sintering aid.