Ultralow-profile high-peel-strength copper-clad plate and preparation method thereof

Abstract

The invention relates to an ultralow-profile high-peel-strength copper-clad plate and a preparation method thereof, and relates to the technical field of printed circuit boards. The copper-clad plate comprises an insulating substrate and an ultra-low profile reverse copper foil which is combined on at least one side of the insulating substrate through hot pressing, the surface roughness Rz of a treated surface of the copper foil is not more than 2.1 microns, and the peel strength is not less than 1.0 N / mm. The preparation method comprises the steps of chemical polishing, micro roughening, curing, alloying, passivation, silane coupling agent treatment and the like, through a multi-step cooperative surface treatment process, the peeling strength is remarkably improved while the surface roughness of the copper foil is reduced, the copper foil is suitable for a printed circuit board for high-frequency communication equipment, and signal transmission performance and reliability are both considered.

Description

Technical Field

[0001] This invention relates to the field of printed circuit board technology, specifically to an ultra-low profile, high peel strength copper-clad laminate and its preparation method. Background Technology

[0002] With the rapid development of technologies such as 5G mobile communication, artificial intelligence, millimeter-wave radar, and satellite communication, signal transmission frequencies have generally increased from below 3GHz to high-frequency bands of 3.5GHz and even above 30GHz. Against this backdrop, the signal transmission loss of printed circuit boards (PCBs), the core carrier of signal transmission, has become a key factor restricting the performance, speed, and stability of the entire communication system.

[0003] Signal loss on printed circuit boards (PCBs) mainly consists of dielectric loss and conductor loss. For high-frequency PCBs operating in the millimeter-wave band, due to the "skin effect," current will be significantly concentrated within an extremely thin layer on the conductor surface. In this case, the microstructure of the conductor surface becomes crucial to signal loss. Traditional copper-clad laminates use standard copper foil (STD) or high-temperature high-ductility copper foil (HTE), which have a high surface roughness profile (Rz typically ≥ 3 μm) when bonded to the resin substrate. This rough surface significantly increases the transmission path of high-frequency current, exacerbates signal scattering, and leads to severe conductor loss, making it difficult to meet the requirements of high-frequency, high-speed applications.

[0004] To reduce losses, the industry has experimented with smoother reverse copper foil (RTF) or other low-profile copper foil (VLP, HVLP). However, reducing the surface roughness of the copper foil often sacrifices its peel strength to the insulating resin substrate. Insufficient adhesion can lead to reliability issues such as copper trace separation from the substrate and blistering during subsequent PCB processing or applications, ultimately causing signal transmission interruptions.

[0005] Therefore, developing a new type of copper-clad laminate that combines ultra-low copper foil surface profile and excellent peel strength to maintain the signal transmission performance and reliability of high-frequency PCBs has become a technical challenge that urgently needs to be solved in this field. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a method for preparing an ultra-low profile, high peel strength copper-clad laminate, comprising the following steps: S1 performs chemical polishing on the smooth surface of the reversed raw copper foil; S2 performs micro-roughening treatment on the polished surface by using a micro-roughening solution containing copper ions, sulfuric acid, high molecular surfactant, amine high molecular organic additive, mercapto-sulfonic acid organic additive and metal salt additive. Electrodeposition is carried out for 3-5 seconds under the conditions of pH 1-2, temperature 20-35℃ and current density 20-30 A / dm² to form a micro-roughening layer. S3 cures the roughened surface by using a curing solution containing copper ions, sulfuric acid, metal salt additives and surfactants. Electrodeposition is performed for 3-4 seconds under the conditions of pH 1-2, temperature 30-45℃ and current density 20-35 A / dm² to form a cured layer. S4 performs alloying treatment on the cured surface by using an alloy liquid containing nickel ions, tungstate ions, citrate ions, zirconium ions and ammonium ions, and electrodepositing for 3-6 seconds under the conditions of pH 6-9, temperature 20-50℃ and current density 3-10 A / dm² to form an alloy layer. S5 performs passivation treatment on the alloyed surface using a passivation solution containing benzotriazole, and processes it for 30-90 seconds at a pH of 5-6 and a temperature of 40-60℃ to form a passivation layer. S6 adds silane coupling agent to a mixture of ethanol and deionized water to form a treatment solution, and then treats the passivated copper foil surface with silane coupling agent, followed by drying to form a silane coupling agent layer, thus obtaining an ultra-low profile reverse copper foil. S7 The processed surface of the ultra-low profile inverted copper foil obtained after steps S1-S6 is bonded to the insulating substrate by hot pressing to form a copper-clad laminate. The peel strength between the copper foil and the insulating substrate in the copper-clad laminate is not less than 1.0 N / mm, and the surface roughness Rz of the copper foil treated surface is not greater than 2.1 μm.

[0007] Preferably, the metal salt additive in step S2 is at least one of choline tungstate, sodium molybdate, stannous sulfate, cobalt sulfate, and titanium sulfate; the metal salt additive in step S3 is at least one of choline tungstate, sodium metavanadate, ferrous sulfate, and cobalt sulfate; and the surfactant is at least one of sodium lauryl polyoxyethylene ether sulfate, sodium dodecyl sulfate, and octadecylamine polyoxyethylene ether.

[0008] Preferably, the polymeric surfactant in step S2 is selected from at least one of polyvinylpyrrolidone, polyethyleneimine, and polyethylene glycol, and the addition amount is 0.01-0.1 g / L; the amine polymeric organic additive is selected from at least one of gelatin, collagen, guar gum, and carrageenan, and the addition amount is 0.005-0.05 g / L; the mercapto-sulfonic acid organic additive is selected from at least one of sodium 2,3-dimercapto-1-propanesulfonate and sodium 3-mercapto-1-propanesulfonate, and the addition amount is 0.01-0.04 g / L.

[0009] Preferably, the alloy liquid in step S4 comprises: nickel sulfate at 7-16 g / L based on nickel ions, choline tungstate at 40-80 g / L based on tungstate ions, citric acid at 10-30 g / L, zirconium sulfate at 2-5 g / L based on zirconium ions, and ammonium sulfate at 3-10 g / L based on ammonium ions.

[0010] Preferably, the silane coupling agent in step S6 is selected from at least one of (3-mercaptopropyl)trimethoxysilane, (3-glycidyl ether propyl)trimethoxysilane, and (3-aminopropyl)trimethoxysilane, and the ratio of ethanol to deionized water is one of 1:9, 2:8, or 3:7, and the pH value of the treatment solution is 4-5.

[0011] An ultra-low profile high peel strength copper-clad laminate includes an insulating substrate and an ultra-low profile inverted copper foil bonded to at least one side thereof by thermo-pressing. The ultra-low profile reverse copper foil has a treated surface that is bonded to an insulating substrate, the surface roughness Rz of the treated surface is not greater than 2.1 μm, and the peel strength between the copper foil and the insulating substrate in the copper-clad laminate is not less than 1.0 N / mm; The processed surface of the ultra-low profile reverse copper foil, from the inside out, includes a roughening layer, a curing layer, an alloying layer, a passivation layer, and a silane coupling agent layer. The micro-roughening layer contains copper and tungsten or molybdenum; the alloying layer contains an alloy of nickel, tungsten and zirconium.

[0012] Preferably, the surface roughness Rz of the treated surface is 1.7 μm to 2.1 μm, and the peel strength is 1.0 N / mm to 1.35 N / mm.

[0013] The present invention also provides a printed circuit board for high-frequency communication equipment, which is made of copper-clad laminate with ultra-low profile and high peel strength as described above.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention utilizes an optimized multi-step synergistic surface treatment process to successfully construct an ultra-low profile microstructure on the smooth surface of inverted copper foil. This significantly reduces the surface roughness Rz of the treated copper foil, which helps to reduce the "skin effect" loss during high-frequency signal transmission. Simultaneously, through a combined electrodeposition process of "micro-roughening-curing-alloying," a special structural layer with high specific surface area and strong interfacial adhesion is constructed on the extremely low profile substrate. This structural layer, in conjunction with subsequent silane coupling agent treatment, produces a synergistic effect, greatly improving the peel strength between the copper foil and the insulating resin substrate. This effectively avoids reliability issues such as delamination and blistering during subsequent processing or use, ensuring the long-term service life and stability of PCB products.

[0015] 2. The treatment liquid system used in this invention avoids the use of highly toxic substances such as cyanide, some of the additives are biodegradable, making it environmentally friendly. Furthermore, this treatment process exhibits excellent adhesion to insulating resin substrates and has promising application prospects. Attached Figure Description

[0016] Figure 1 The figures show the peel strength test results of the embodiments and comparative examples of the present invention; Figure 2 This is a scanning electron microscope image of the untreated inverted copper foil of the present invention. Figure 3 This is a scanning electron microscope image of the polished copper foil surface of the present invention. Figure 4 This is a scanning electron microscope image of the copper foil prepared in Example 1 of the present invention; Figure 5 This is a magnified scanning electron microscope image of the copper foil prepared in Example 1 of the present invention; Figure 6 This is a magnified scanning electron microscope image of the copper foil obtained in Example 5 of the present invention; Figure 7 This is a scanning electron microscope image of the copper foil in Comparative Example 3 of the present invention; Figure 8 This is a scanning electron microscope image of the resin board surface before the peel strength test in Embodiment 1 of the present invention; Figure 9 This is a scanning electron microscope image of the resin board surface after the peel strength test in Embodiment 1 of the present invention. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The listed embodiments are only a part of the embodiments of the present invention, and not all of them. Furthermore, the scope of protection of the present invention is not limited to the following embodiments. Adjustments and improvements made under the premise of the present invention are all within the scope of protection of the present invention. At the same time, the numerical range in the present invention should be understood as each intermediate value between the upper and lower limits of the range has been specifically disclosed, and any stated value or intermediate value within the stated range, as well as each smaller range between other stated values ​​and intermediate values ​​within the stated range, are also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range. Example 1

[0018] A method for preparing an ultra-low profile, high peel strength copper-clad laminate includes the following steps: S1 polishing solution treatment: Weigh 30% hydrogen peroxide, 1% sulfuric acid, and 0.5 g benzotriazole by volume ratio, add 690 mL of deionized water and stir to dissolve to obtain polishing solution; immerse the smooth side of the reversed raw copper foil for 30 s, rinse with deionized water, and blow dry to obtain polished reversed copper foil; S2 Micro-roughening treatment: 45 g copper sulfate pentahydrate, 70 mL sulfuric acid, 50 mg choline tungstate, 15 mg polyvinylpyrrolidone, 5 mg polyethylene glycol, 15 mg gelatin, 40 mg sodium 2,3-dimercapto-1-propanesulfonate and 10 mg sodium chloride were added to deionized water and heated and stirred until dissolved to 1 L to obtain a micro-roughening solution; the cooled micro-roughening solution was poured into an electrolytic cell, the copper foil polished in step S1 was used as the cathode, the iridium-plated titanium plate was used as the anode, the pH was 2, the temperature was 25℃, the current density was 25 A / dm², and after electrodeposition for 3 s, the micro-roughened copper foil was taken out; S3 Curing Treatment: 145 g copper sulfate pentahydrate, 65 mL sulfuric acid, 25 mg sodium metavanadate, and 30 mg octadecylamine polyoxyethylene ether were added to deionized water and stirred until 1 L of curing solution was obtained. The curing solution was poured into an electrolytic cell. The surface of the micro-roughened reverse copper foil obtained in step S2 was used as the cathode, and the iridium-plated titanium plate was used as the anode. The pH was 2, the temperature was 35℃, and the current density was 20 A / dm². After electrodeposition for 3 s, the foil was taken out, rinsed with deionized water, and dried to obtain the cured reverse copper foil. S4 Alloy Treatment: 66 g choline tungstate, 30 g nickel sulfate, 10 g citric acid, 20 g ammonium sulfate and 10 g zirconium sulfate were added to deionized water and stirred until dissolved to 1 L. The pH was adjusted to 8.5. The alloy solution was poured into an electrolytic cell. The surface of the solidified reverse copper foil obtained in step S3 was used as the cathode and the iridium-plated titanium plate was used as the anode. The current density was 3 A / dm², the temperature was 35℃, and the electrodeposition time was 5 s. After electrodeposition, the foil was taken out, rinsed with deionized water, and dried to obtain the alloyed reverse copper foil. S5 passivation treatment: 2.5 g of benzotriazole was added to deionized water and stirred until dissolved to 1 L. Sodium hydroxide was used to adjust the pH to 5 and the temperature to 50℃. The alloyed reverse copper foil obtained in step S4 was soaked for 60 seconds, then taken out and rinsed with deionized water and dried to obtain passivated reverse copper foil. S6 Silane treatment: 10 ml of (3-glycidyl ether propyl)trimethoxysilane was added to a mixture of deionized water and ethanol, wherein the ratio of ethanol to deionized water was 2:8. The pH was adjusted to 4 with acetic acid, the temperature was 30 ℃, and the treatment time was 40 s. The passivated reverse copper foil obtained in step S5 was coated with silane solution, and then placed in an 80 ℃ oven for 30 min to obtain ultra-low profile reverse copper foil. S7. Cut the ultra-low profile reverse copper foil obtained in step S6 into 4mm strips with a cutter, and then press the surface-treated surface with semi-cured resin. The hot pressing temperature is 175 ℃ and the time is 1 h to obtain copper-clad laminate. Copper-clad laminate peel test: After peeling off one side of the copper foil, clamp it with the peeling machine clamp and fix it on the weight. Then fix the remaining resin sheet on the peeling instrument with an iron sheet and perform a 90° peel test. Each sample is tested 3 times and the average value is taken. Example 2

[0019] A method for preparing an ultra-low profile, high peel strength copper-clad laminate includes the following steps: S1 polishing solution treatment: Weigh 30% hydrogen peroxide, 1% sulfuric acid, and 0.5 g benzotriazole by volume ratio, add 690 mL of deionized water and stir to dissolve to obtain polishing solution; immerse the smooth side of the reversed raw copper foil for 30 s, rinse with deionized water, and blow dry to obtain polished reversed copper foil; S2 Micro-roughening treatment: 45 g copper sulfate pentahydrate, 70 mL sulfuric acid, 50 mg choline tungstate, 15 mg polyethyleneimine, 15 mg carrageenan, 5 mg collagen, 20 mg sodium 3-mercapto-1-propanesulfonate and 10 mg sodium chloride were added to deionized water and heated and stirred until dissolved to 1 L to obtain a micro-roughening solution; the cooled micro-roughening solution was poured into an electrolytic cell, the copper foil polished in step S1 was used as the cathode, and the iridium-plated titanium plate was used as the anode, the pH was 1, the temperature was 20℃, the current density was 20 A / dm², and after electrodeposition for 4 s, the micro-roughened copper foil was taken out; S3 Curing Treatment: 145 g copper sulfate pentahydrate, 65 mL sulfuric acid, 25 mg sodium metavanadate, and 40 mg choline tungstate were added to deionized water and stirred until dissolved to 1 L of curing solution. The curing solution was poured into an electrolytic cell. The surface of the micro-roughened reverse copper foil obtained in step S2 was used as the cathode, and the iridium-plated titanium plate was used as the anode. The pH was 1, the temperature was 30℃, and the current density was 35 A / dm². After electrodeposition for 4 s, the foil was removed, rinsed with deionized water, and dried to obtain the cured reverse copper foil. S4 Alloy Treatment: 66 g choline tungstate, 30 g nickel sulfate, 30 g citric acid, 20 g ammonium sulfate, and 10 g zirconium sulfate were added to a deionizer and stirred until dissolved to 1 L. The pH was adjusted to 8. The alloy solution was poured into an electrolytic cell. The surface of the cured reverse copper foil obtained in step S3 was used as the cathode, and the iridium-plated titanium plate was used as the anode. The current density was 3 A / dm², the temperature was 20℃, and the electrodeposition time was 5 s. After electrodeposition, the foil was removed, rinsed with deionized water, and dried to obtain the alloyed reverse copper foil. S5 passivation treatment: 2.5 g of benzotriazole was added to deionized water and stirred until dissolved to 1 L. Sodium hydroxide was used to adjust the pH to 5 and the temperature to 40℃. The alloyed reverse copper foil obtained in step S4 was soaked for 30 seconds, then taken out and rinsed with deionized water and dried to obtain passivated reverse copper foil. S6 Silane treatment: 10 ml of (3-mercaptopropyl)trimethoxysilane was added to a mixture of deionized water and ethanol, wherein the ratio of ethanol to deionized water was 1:9. The pH was adjusted to 5 with acetic acid, the temperature was 20℃, and the treatment time was 40 s. The passivated reverse copper foil obtained in step S5 was coated with silane solution, and then placed in an 80℃ oven for 30 min to obtain ultra-low profile reverse copper foil. S7. Cut the ultra-low profile reverse copper foil obtained in step S6 into 4mm strips with a cutter, and then press the surface-treated surface with semi-cured resin. The hot pressing temperature is 175 ℃ and the time is 1 h to obtain copper-clad laminate. Copper-clad laminate peel test: After peeling off one side of the copper foil, clamp it with the peeling machine clamp and fix it on the weight. Then fix the remaining resin sheet on the peeling instrument with an iron sheet and perform a 90° peel test. Each sample is tested 3 times and the average value is taken. Example 3

[0020] A method for preparing an ultra-low profile, high peel strength copper-clad laminate includes the following steps: S1 polishing solution treatment: Weigh 30% hydrogen peroxide, 1% sulfuric acid, and 0.5 g benzotriazole by volume ratio, add 690 mL of deionized water and stir to dissolve to obtain polishing solution; immerse the smooth side of the reversed raw copper foil for 30 s, rinse with deionized water, and blow dry to obtain polished reversed copper foil; S2 Micro-roughening treatment: 45 g copper sulfate pentahydrate, 70 mL sulfuric acid, 35 mg sodium molybdate, 20 mg stannous sulfate, 15 mg polyvinylpyrrolidone, 5 mg guar gum, 30 mg sodium 2,3-dimercapto-1-propanesulfonate and 10 mg sodium chloride were added to deionized water and heated and stirred until dissolved to 1 L to obtain a micro-roughening solution; the cooled micro-roughening solution was poured into an electrolytic cell, and the polished copper foil from step S1 was used as the cathode, and the iridium-plated titanium plate was used as the anode. The pH was 2, the temperature was 35℃, the current density was 25 A / dm², and after electrodeposition for 5 s, the micro-roughened copper foil was taken out. S3 Curing Treatment: 145 g copper sulfate pentahydrate, 65 mL sulfuric acid, 25 mg sodium metavanadate, and 30 mg sodium stearate were added to deionized water and stirred until dissolved to 1 L of curing solution. The curing solution was poured into an electrolytic cell. The surface of the micro-roughened reverse copper foil obtained in step S2 was used as the cathode, and the iridium-plated titanium plate was used as the anode. The pH was 2, the temperature was 45℃, and the current density was 20 A / dm². After electrodeposition for 3 s, the foil was taken out, rinsed with deionized water, and dried to obtain the cured reverse copper foil. S4 Alloy Treatment: 66 g choline tungstate, 30 g nickel sulfate, 20 g citric acid, 20 g ammonium sulfate, and 10 g zirconium sulfate were added to a deionizer and stirred until dissolved to 1 L. The pH was adjusted to 6. The alloy solution was poured into an electrolytic cell. The surface of the cured reverse copper foil obtained in step S3 was used as the cathode, and the iridium-plated titanium plate was used as the anode. The current density was 3 A / dm², the temperature was 50℃, and the electrodeposition time was 5 s. After electrodeposition, the foil was removed, rinsed with deionizer, and dried to obtain the alloyed reverse copper foil. S5 passivation treatment: 2.5 g of benzotriazole was added to deionized water and stirred until dissolved to 1 L. Sodium hydroxide was used to adjust the pH to 6 and the temperature to 60℃. The alloyed reverse copper foil obtained in step S4 was soaked for 60 seconds, then taken out and rinsed with deionized water and dried to obtain passivated reverse copper foil. S6 Silane treatment: 10 ml of (3-glycidyl ether propyl)trimethoxysilane was added to a mixture of deionized water and ethanol, wherein the ratio of ethanol to deionized water was 1:9. The pH was adjusted to 4 with acetic acid, the temperature was 20℃, and the treatment time was 20s. The passivated reverse copper foil obtained in step S5 was coated with the silane solution, and then placed in an 80℃ oven for 30 min to obtain an ultra-low profile reverse copper foil. S7. Cut the ultra-low profile reverse copper foil obtained in step S6 into 4mm strips with a cutter, and then press the surface-treated surface with semi-cured resin. The hot pressing temperature is 175 ℃ and the time is 1 h to obtain copper-clad laminate. Copper-clad laminate peel test: After peeling off one side of the copper foil, clamp it with the peeling machine clamp and fix it on the weight. Then fix the remaining resin sheet on the peeling instrument with an iron sheet and perform a 90° peel test. Each sample is tested 3 times and the average value is taken. Example 4

[0021] A method for preparing an ultra-low profile, high peel strength copper-clad laminate includes the following steps: S1 polishing solution treatment: Weigh 30% hydrogen peroxide, 1% sulfuric acid, and 0.5 g benzotriazole by volume ratio, add 690 mL of deionized water and stir to dissolve to obtain polishing solution; immerse the smooth side of the reversed raw copper foil for 30 s, rinse with deionized water, and blow dry to obtain polished reversed copper foil; S2 Micro-roughening treatment: 45 g copper sulfate pentahydrate, 70 mL sulfuric acid, 35 mg choline tungstate, 20 mg sodium molybdate, 15 mg polyethyleneimine, 5 mg guar gum, 10 mg sodium 3-mercapto-1-propanesulfonate and 10 mg sodium chloride were added to deionized water and heated and stirred until dissolved to 1 L to obtain a micro-roughening solution; the cooled micro-roughening solution was poured into an electrolytic cell, the copper foil in step S1 polishing treatment was used as the cathode, and the iridium-plated titanium plate was used as the anode, the pH was 2, the temperature was 30℃, the current density was 30 A / dm², and after electrodeposition for 5 s, the micro-roughened copper foil was taken out; S3 Curing Treatment: 145 g copper sulfate pentahydrate, 65 mL sulfuric acid, 25 mg sodium metavanadate, 10 mg ferrous sulfate and 20 mg sodium lauryl ether sulfate were added to deionized water and stirred until 1 L of curing solution was obtained. The curing solution was poured into an electrolytic cell. The surface of the micro-roughened reverse copper foil obtained in step S2 was used as the cathode and the iridium-plated titanium plate was used as the anode. The pH was 2, the temperature was 40℃ and the current density was 20 A / dm². After electrodeposition for 3 s, the copper foil was taken out, rinsed with deionized water and dried to obtain the cured reverse copper foil. S4 Alloy Treatment: 66 g choline tungstate, 30 g nickel sulfate, 30 g citric acid, 20 g ammonium sulfate, and 10 g zirconium sulfate were added to a deionizer and stirred until dissolved to 1 L. The pH was adjusted to 7. The alloy solution was poured into an electrolytic cell. The surface of the cured reverse copper foil obtained in step S3 was used as the cathode, and the iridium-plated titanium plate was used as the anode. The current density was 3 A / dm², the temperature was 40℃, and the electrodeposition time was 5 s. After electrodeposition, the foil was removed, rinsed with deionizer, and dried to obtain the alloyed reverse copper foil. S5 passivation treatment: 2.5 g of benzotriazole was added to deionized water and stirred until dissolved to 1 L. Sodium hydroxide was used to adjust the pH to 5 and the temperature to 40℃. The alloyed reverse copper foil obtained in step S4 was soaked for 60 seconds, then taken out and rinsed with deionized water and dried to obtain passivated reverse copper foil. S6 Silane Treatment: 10 ml of (3-aminopropyl)trimethoxysilane was added to a mixture of deionized water and ethanol, wherein the ratio of ethanol to deionized water was 2:8. The pH was adjusted to 4.5 with acetic acid, the temperature was 30 ℃, and the treatment time was 20 s. The passivated reverse copper foil obtained in step S5 was coated with the silane solution, and then placed in an 80 ℃ oven for 30 min to obtain an ultra-low profile reverse copper foil. S7. Cut the ultra-low profile reverse copper foil obtained in step S6 into 4mm strips with a cutter, and then press the surface-treated surface with semi-cured resin. The hot pressing temperature is 175 ℃ and the time is 1 h to obtain copper-clad laminate. Copper-clad laminate peel test: After peeling off one side of the copper foil, clamp it with the peeling machine clamp and fix it on the weight. Then fix the remaining resin sheet on the peeling instrument with an iron sheet and perform a 90° peel test. Each sample is tested 3 times and the average value is taken. Example 5

[0022] A method for preparing an ultra-low profile, high peel strength copper-clad laminate includes the following steps: S1 polishing solution treatment: Weigh 30% hydrogen peroxide, 1% sulfuric acid, and 0.5 g benzotriazole by volume ratio, add 690 mL of deionized water and stir to dissolve to obtain polishing solution; immerse the smooth side of the reversed raw copper foil for 30 s, rinse with deionized water, and blow dry to obtain polished reversed copper foil; S2 Micro-roughening treatment: 45 g copper sulfate pentahydrate, 70 mL sulfuric acid, 50 mg choline tungstate, 20 mg cobalt sulfate, 15 mg polyvinylpyrrolidone, 5 mg collagen, 30 mg sodium 2,3-dimercapto-1-propanesulfonate and 10 mg sodium chloride were added to deionized water and heated and stirred until dissolved to 1 L to obtain a micro-roughening solution; the cooled micro-roughening solution was poured into an electrolytic cell, the copper foil polished in step S1 was used as the cathode, and the iridium-plated titanium plate was used as the anode, the pH was 2, the temperature was 25℃, the current density was 25 A / dm², and after electrodeposition for 5 s, the micro-roughened copper foil was taken out; S3 Curing Treatment: 145 g copper sulfate pentahydrate, 65 mL sulfuric acid, 25 mg sodium metavanadate, 20 mg sodium dodecyl sulfate and 20 mg choline tungstate were added to deionized water and stirred until 1 L of curing solution was obtained. The curing solution was poured into an electrolytic cell. The surface of the micro-roughened reverse copper foil obtained in step S2 was used as the cathode and the iridium-plated titanium plate was used as the anode. The pH was 2, the temperature was 35℃ and the current density was 20 A / dm². After electrodeposition for 3 s, the foil was taken out, rinsed with deionized water and dried to obtain the cured reverse copper foil. S4 Alloy Treatment: 66 g choline tungstate, 30 g nickel sulfate, 10 g citric acid, 20 g ammonium sulfate, and 10 g zirconium sulfate were added to a deionizer and stirred until dissolved to 1 L. The pH was adjusted to 9. The alloy solution was poured into an electrolytic cell. The surface of the cured reverse copper foil obtained in step S3 was used as the cathode, and the iridium-plated titanium plate was used as the anode. The current density was 10 A / dm², the temperature was 40℃, and the electrodeposition time was 5 s. After electrodeposition, the foil was removed, rinsed with deionizer, and dried to obtain the alloyed reverse copper foil. S5 passivation treatment: 2.5 g of benzotriazole was added to deionized water and stirred until dissolved to 1 L. Sodium hydroxide was used to adjust the pH to 6 and the temperature to 50℃. The alloyed reverse copper foil obtained in step S4 was soaked for 90 seconds, then taken out and rinsed with deionized water and dried to obtain passivated reverse copper foil. S6 Silane Treatment: 10 ml of (3-glycidyl ether propyl)trimethoxysilane was added to a mixture of deionized water and ethanol, wherein the ratio of ethanol to deionized water was 3:7. The pH was adjusted to 5 with acetic acid, the temperature was 25℃, and the treatment time was 30 s. The passivated reverse copper foil obtained in step S5 was coated with the silane solution, and then placed in an 80℃ oven for 30 min to obtain an ultra-low profile reverse copper foil. S7. Cut the ultra-low profile reverse copper foil obtained in step S6 into 4mm strips with a cutter, and then press the surface-treated surface with semi-cured resin. The hot pressing temperature is 175 ℃ and the time is 1 h to obtain copper-clad laminate. Copper-clad laminate peel test: After peeling off one side of the copper foil, clamp it with the peeling machine clamp and fix it on the weight. Then fix the remaining resin sheet on the peeling instrument with an iron sheet and perform a 90° peel test. Each sample is tested 3 times and the average value is taken. Example 6

[0023] A method for preparing an ultra-low profile, high peel strength copper-clad laminate includes the following steps: S1 polishing solution treatment: Weigh 30% hydrogen peroxide, 1% sulfuric acid, and 0.5 g benzotriazole by volume ratio, add 690 mL of deionized water and stir to dissolve to obtain polishing solution; immerse the smooth side of the reversed raw copper foil for 30 s, rinse with deionized water, and blow dry to obtain polished reversed copper foil; S2 Micro-roughening treatment: 45 g copper sulfate pentahydrate, 70 mL sulfuric acid, 50 mg choline tungstate, 20 mg titanium sulfate, 10 mg polyethylene glycol, 5 mg guar gum, 30 mg sodium 3-mercapto-1-propanesulfonate and 10 mg sodium chloride were added to deionized water and heated and stirred until dissolved to 1 L to obtain a micro-roughening solution; the cooled micro-roughening solution was poured into an electrolytic cell, the copper foil polished in step S1 was used as the cathode, the iridium-plated titanium plate was used as the anode, the pH was 2, the temperature was 20℃, the current density was 25 A / dm², and after electrodeposition for 5 s, the micro-roughened copper foil was taken out; S3 Curing Treatment: 145 g copper sulfate pentahydrate, 65 mL sulfuric acid, 25 mg sodium metavanadate, 10 mg cobalt sulfate and 20 mg octadecylamine polyoxyethylene ether were added to deionized water and stirred until 1 L of curing solution was obtained; the curing solution was poured into an electrolytic cell, the micro-roughened reverse copper foil surface obtained in step S2 was used as the cathode, the iridium-plated titanium plate was used as the anode, the pH was 2, the temperature was 30℃, the current density was 20 A / dm², after electrodeposition for 3 s, it was taken out, rinsed with deionized water, and dried to obtain the cured reverse copper foil; S4 Alloy Treatment: 66 g choline tungstate, 30 g nickel sulfate, 30 g citric acid, 20 g ammonium sulfate, and 10 g zirconium sulfate were added to a deionizer and stirred until dissolved to 1 L. The pH was adjusted to 8.5. The alloy solution was poured into an electrolytic cell. The surface of the cured reverse copper foil obtained in step S3 was used as the cathode, and the iridium-plated titanium plate was used as the anode. The current density was 6 A / dm², the temperature was 30℃, and the electrodeposition time was 5 s. After electrodeposition, the foil was removed, rinsed with deionizer, and dried to obtain the alloyed reverse copper foil. S5 passivation treatment: 2.5 g of benzotriazole was added to deionized water and stirred until dissolved to 1 L. Sodium hydroxide was used to adjust the pH to 5 and the temperature to 40℃. The alloyed reverse copper foil obtained in step S4 was soaked for 90 seconds, then taken out and rinsed with deionized water and dried to obtain passivated reverse copper foil. S6 Silane Treatment: 10 ml of (3-glycidyl ether propyl)trimethoxysilane was added to a mixture of deionized water and ethanol, wherein the ratio of ethanol to deionized water was 2:8. The pH was adjusted to 5 with acetic acid, the temperature was 30 ℃, and the treatment time was 40 s. The passivated reverse copper foil obtained in step S5 was coated with the silane solution, and then placed in an 80 ℃ oven for 30 min to obtain an ultra-low profile reverse copper foil. S7. Cut the ultra-low profile reverse copper foil obtained in step S6 into 4mm strips with a cutter, and then press the surface-treated surface with semi-cured resin. The hot pressing temperature is 175 ℃ and the time is 1 h to obtain copper-clad laminate. Copper-clad laminate peel test: After peeling off one side of the copper foil, clamp it with the peeling machine clamp and fix it on the weight. Then fix the remaining resin sheet on the peeling instrument with an iron sheet and perform a 90° peel test. Each sample is tested 3 times and the average value is taken.

[0024] Comparative Example 1 The difference from Example 1 is that the current density for the micro-coarsening treatment is 15 A / dm². Comparative Example 2 The difference from Example 1 is that the S3 curing treatment is not performed after the micro-roughening treatment. Comparative Example 3 The difference from Example 1 is that the single process of micro-roughening-curing is changed to a two-stage process of micro-roughening-curing-micro-roughening-curing.

[0025] The copper-clad laminate peel test conditions for each comparative example were consistent with those in the aforementioned embodiments, and the final peel test results were as follows: Figure 1 As shown, for reference Figures 2 to 9As shown, the results indicate that a current density of 20-25 A / dm² is more suitable for the granular copper particle morphology on the surface of the copper foil after surface treatment, resulting in stronger bonding between the copper foil and the resin board, and higher peel strength of the copper-clad laminate. The curing step involves copper particle growth, which increases the surface roughness of the copper foil. However, this process is crucial to prevent copper particles from detaching and adhering to the resin board, thus reducing the peel strength of the copper-clad laminate. This step cannot be omitted, and under the same process conditions, the electrodeposition time for this step should be shorter. A multi-step roughening-curing process can cause copper particles on the copper foil surface to aggregate and grow, forming agglomerated copper nodules, leading to increased surface roughness. However, because the agglomerated copper particles are larger, the peel strength of the copper-clad laminate increases. Therefore, to ensure low surface roughness of the copper foil, a single roughening-curing process can be chosen under the same process conditions.

Claims

1. A method for preparing an ultra-low profile, high peel strength copper-clad laminate, characterized in that, Includes the following steps: S1 performs chemical polishing on the smooth surface of the reversed raw copper foil; S2 performs micro-roughening treatment on the polished surface by using a micro-roughening solution containing copper ions, sulfuric acid, high molecular surfactant, amine high molecular organic additive, mercapto-sulfonic acid organic additive and metal salt additive. Electrodeposition is carried out for 3-5 seconds under the conditions of pH 1-2, temperature 20-35℃ and current density 20-30 A / dm² to form a micro-roughening layer. S3 cures the roughened surface by using a curing solution containing copper ions, sulfuric acid, metal salt additives and surfactants. Electrodeposition is performed for 3-4 seconds under the conditions of pH 1-2, temperature 30-45℃ and current density 20-35 A / dm² to form a cured layer. S4 performs alloying treatment on the cured surface by using an alloy liquid containing nickel ions, tungstate ions, citrate ions, zirconium ions and ammonium ions, and electrodepositing for 3-6 seconds under the conditions of pH 6-9, temperature 20-50℃ and current density 3-10 A / dm² to form an alloy layer. S5 performs passivation treatment on the alloyed surface using a passivation solution containing benzotriazole, and processes it for 30-90 seconds at a pH of 5-6 and a temperature of 40-60℃ to form a passivation layer. S6 adds silane coupling agent to a mixture of ethanol and deionized water to form a treatment solution, and then treats the passivated copper foil surface with silane coupling agent, followed by drying to form a silane coupling agent layer, thus obtaining an ultra-low profile reverse copper foil. S7 The processed surface of the ultra-low profile inverted copper foil obtained after steps S1-S6 is bonded to the insulating substrate by hot pressing to form a copper-clad laminate. The peel strength between the copper foil and the insulating substrate in the copper-clad laminate is not less than 1.0 N / mm, and the surface roughness Rz of the copper foil treated surface is not greater than 2.1 μm.

2. The method for preparing ultra-low profile, high peel strength copper-clad laminate according to claim 1, characterized in that, The metal salt additive in step S2 is at least one of choline tungstate, sodium molybdate, stannous sulfate, cobalt sulfate, and titanium sulfate; the metal salt additive in step S3 is at least one of choline tungstate, sodium metavanadate, ferrous sulfate, and cobalt sulfate, and the surfactant is at least one of sodium lauryl polyoxyethylene ether sulfate, sodium dodecyl sulfate, and octadecylamine polyoxyethylene ether.

3. The method for preparing ultra-low profile, high peel strength copper-clad laminate according to claim 1, characterized in that, In step S2, the polymeric surfactant is selected from at least one of polyvinylpyrrolidone, polyethyleneimine, and polyethylene glycol, and the addition amount is 0.01-0.1 g / L; the amine polymeric organic additive is selected from at least one of gelatin, collagen, guar gum, and carrageenan, and the addition amount is 0.005-0.05 g / L; the mercapto-sulfonic acid organic additive is selected from at least one of sodium 2,3-dimercapto-1-propanesulfonate and sodium 3-mercapto-1-propanesulfonate, and the addition amount is 0.01-0.04 g / L.

4. The method for preparing ultra-low profile, high peel strength copper-clad laminate according to claim 1, characterized in that, The alloy liquid in step S4 comprises: nickel sulfate at a concentration of 7-16 g / L based on nickel ions, choline tungstate at a concentration of 40-80 g / L based on tungstate ions, citric acid at a concentration of 10-30 g / L, zirconium sulfate at a concentration of 2-5 g / L based on zirconium ions, and ammonium sulfate at a concentration of 3-10 g / L based on ammonium ions.

5. The method for preparing ultra-low profile, high peel strength copper-clad laminate according to claim 1, characterized in that, The silane coupling agent in step S6 is selected from at least one of (3-mercaptopropyl)trimethoxysilane, (3-glycidyl ether propyl)trimethoxysilane, and (3-aminopropyl)trimethoxysilane, and the ratio of ethanol to deionized water is one of 1:9, 2:8, or 3:7, and the pH value of the treatment solution is 4-5.

6. A copper-clad laminate with ultra-low profile and high peel strength, characterized in that, Includes an insulating substrate and an ultra-low profile inverted copper foil bonded to at least one side thereof by thermo-pressing; The ultra-low profile reverse copper foil has a treated surface that is bonded to an insulating substrate, the surface roughness Rz of the treated surface is not greater than 2.1 μm, and the peel strength between the copper foil and the insulating substrate in the copper-clad laminate is not less than 1.0 N / mm; The processed surface of the ultra-low profile reverse copper foil, from the inside out, includes a roughening layer, a curing layer, an alloying layer, a passivation layer, and a silane coupling agent layer. The micro-roughening layer contains copper and tungsten or molybdenum; the alloying layer contains an alloy of nickel, tungsten and zirconium.

7. The ultra-low profile, high peel strength copper-clad laminate according to claim 6, characterized in that, The surface roughness Rz of the treated surface is 1.7 μm to 2.1 μm, and the peel strength is 1.0 N / mm to 1.35 N / mm.

8. A printed circuit board for a high-frequency communication device, characterized in that, It is made using an ultra-low profile, high peel strength copper-clad laminate as described in claim 6 or 7.

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