A resin composition for a high-transparency low-expansion coefficient copper-clad plate, a copper-clad plate, and a method for manufacturing the same

Abstract

The present application relates to copper-clad plate material technical field, specifically to a kind of high transparent low expansion coefficient resin composition for copper-clad plate, copper-clad plate and preparation method thereof.The present application discloses a kind of high transparent low expansion coefficient resin composition for copper-clad plate, copper-clad plate and preparation method thereof, its resin composition includes epoxy modified polysiloxane, hydroxyl-terminated polyphenyl ether, phosphorus-containing epoxy resin, methyl hexacyanophthalic anhydride, polyhedral oligomeric silesquioxane, vinyl silane modified hollow SiO2, spherical fused SiO2, benzoxazine-siloxane bifunctional interface compatibilizer and N,N-dimethyl benzylamine.The preparation method is to synthesize key component first, then resin and pre-dispersed filler slurry are gently compounded to obtain glue solution, then impregnated, dried to prepare prepreg, finally with copper foil is stacked and is cured to obtain copper-clad plate product, the obtained copper-clad plate substrate has high light transmittance, low thermal expansion and excellent high-frequency performance.

Description

Technical Field

[0001] This invention relates to the field of copper clad laminate materials technology, specifically to a resin composition for high-transparency, low-expansion-coefficient copper clad laminates, copper clad laminates, and their preparation methods. Background Technology

[0002] Copper-clad laminates (CCLs) are a fundamental material used in the electronics industry for manufacturing printed circuit boards (PCBs). They are typically made by impregnating reinforcing materials with resin, coating them with copper foil, and then curing them under heat and pressure. Epoxy resin is a common CCL material, and polyphenylene oxide (PPE) is a thermoplastic resin with extremely low dielectric constant, low dielectric loss, low moisture absorption, and high heat resistance. Introducing PPE into the epoxy resin matrix can improve the dielectric and heat resistance properties of the CCL. However, PPE and epoxy resin are thermodynamically incompatible systems; direct blending will result in significant phase separation, which will not only lead to a decrease in material transparency and mechanical properties but also weaken the bond strength between the resin matrix and the copper foil interface.

[0003] Existing technologies improve the compatibility between epoxy resin and PPE by reducing the molecular weight of PPE, introducing active groups into the PPE molecular structure, adding compatibilizers, or constructing interpenetrating networks. For example, CN121133224A discloses a polyphenylene ether-modified epoxy resin-based copper clad laminate and its preparation method. It uses bisphenol A type epoxy resin, toluene, and benzoyl peroxide to treat polyphenylene ether, which reduces the molecular weight of polyphenylene ether, resulting in better crosslinking between polyphenylene ether and epoxy resin. Then, it uses paraformaldehyde for catalytic modification of polyphenylene ether, grafting hydroxymethyl groups onto the ends of the polyphenylene ether. The resulting hydroxymethylated polyphenylene ether has good compatibility and interfacial bonding with epoxy resin, effectively improving the dielectric loss of the copper clad laminate. Regarding performance and toughness, anhydrous aluminum silicate, formed by the controlled-temperature calcination of kaolin through a specific activation treatment, exhibits an amorphous layered void structure, which significantly reduces the dielectric constant and dielectric loss of copper-clad laminates. CN119350635A discloses a hydrocarbon resin with high adhesion and low dielectric loss, its preparation method, and applications. This method utilizes hydrocarbon resin, double-bonded epoxy resin, triallyl isocyanurate, and hydroxyl-terminated polyphenylene ether as raw materials, significantly increasing the crosslinking density of the resin and thus improving its mechanical and thermal properties. The introduction of bisphenol fluorene improves the rigidity and heat resistance of the hydrocarbon resin, while also introducing more hydroxyl groups, enhancing the adhesion between the hydrocarbon resin and the substrate. However, pure cyclic olefin polymers are typically thermoplastic with low glass transition temperatures and high coefficients of thermal expansion, resulting in insufficient heat resistance and dimensional stability during copper-clad laminate lamination and subsequent welding processes, making them unsuitable for direct use as a resin matrix for copper-clad laminates.

[0004] In summary, how to combine intrinsically low dielectric nonpolar or low polar polymers with thermosetting resins while ensuring high transparency and low expansion performance of the system has become an urgent technical problem to be solved. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a resin composition for high-transparency, low-expansion coefficient copper-clad laminates, copper-clad laminates and their preparation methods, so as to solve the technical problems in the prior art, such as the inability to balance transparency and functionality and the inevitable decrease in light transmittance due to high filling.

[0006] The specific technical solution is as follows:

[0007] A resin composition for high-transparency, low-expansion-coefficient copper-clad laminates, the copper-clad laminate, and a method for preparing the same are disclosed. The resin composition comprises the following components, with each component content calculated based on 48-52 parts by weight of the epoxy-modified polysiloxane: 48-52 parts epoxy-modified polysiloxane, 16-20 parts hydroxyl-terminated polyphenylene ether, 8.5 parts methyl hexacyanamide, 3-5 parts epoxy polyhedral oligomeric silsesquioxane, 6-10 parts vinylsilane-modified hollow SiO2, 4-8 parts spherical molten SiO2, 0.5-1.5 parts benzoxazine-siloxane bifunctional interface compatibilizer, 0.3 parts N,N-dimethylbenzylamine, and 20 parts butanone solvent.

[0008] Furthermore, the epoxy-modified polysiloxane copolymer is a polydimethylsiloxane with epoxy propoxy groups in the side chain, having a number-average molecular weight of 3000-8000 and an epoxy equivalent of 3000-5000 g / eq, and the epoxy groups are connected to the siloxane backbone through C3 alkoxy bridges.

[0009] Furthermore, the spherical molten SiO2 is a spherical amorphous SiO2 surface-treated with vinylsilane, with an average particle size of 0.5~2μm, a sphericity ≥95%, and a refractive index of 1.45~1.46, and its surface forms Si-SC covalent bonds with the resin matrix through a thiol-epoxy click reaction.

[0010] Furthermore, the benzoxazine-siloxane bifunctional interface compatibilizer is a compound containing both a benzoxazine ring and a siloxane segment, and the hydrogen content of the siloxane segment is 0.1~1.0 wt%.

[0011] Furthermore, the copper clad laminate includes at least one insulating layer reinforced with ultra-thin open-fiber electronic-grade glass fiber cloth, the insulating layer being formed by impregnation and curing of the resin composition; and an RTF copper foil laminated on at least one surface of the insulating layer.

[0012] A resin composition for high-transparency, low-expansion-coefficient copper-clad laminates, the copper-clad laminate itself, and a method for preparing the same, comprising the following steps: S1: In a reaction flask equipped with a stirrer, thermometer, and reflux condenser, add 1,3,5,7-tetrahydro-1,3,5,7-tetramethylcyclotetrasiloxane, allyl glycidyl ether, and isopropanol chloroplatinate solution. Stir the reaction under nitrogen protection. After the reaction is complete, dissolve the product in toluene, pour into excess methanol to precipitate, filter, and vacuum dry to obtain epoxy-modified polysiloxane for later use. Phenol, allylamine, paraformaldehyde, and toluene are mixed and refluxed to generate an allyl-functionalized benzoxazine precursor. The mixture is then cooled, and hydrogen-containing silicone oil and isopropanol chloroplatinate solution are added, followed by heating to react. The solvent is removed by vacuum distillation to obtain a benzoxazine-siloxane bifunctional interfacial compatibilizer for later use.

[0013] S2: Epoxy-modified polysiloxane, hydroxyl-terminated polyphenylene ether, and epoxy-based POSS are added to the reactor. After vacuum melting, the mixture is cooled and discharged to obtain the main mixture. The main mixture is transferred to a planetary reactor and maintained at 50°C and 40 rpm. Butanone is used as a pre-dispersion carrier, and vinylsilane-modified hollow SiO2, spherical molten SiO2, and benzoxazine-siloxane bifunctional interface compatibilizer are added sequentially. The mixture is first sheared at high speed to form a uniform slurry. This slurry is then slowly introduced into the planetary reactor and gently stirred with the main mixture. Finally, methyl hexacyanamide and N,N-dimethylbenzylamine are added, and the mixture is stirred at a certain speed to obtain the final adhesive solution.

[0014] S3: Transfer the adhesive liquid into a constant temperature pressure tank, and then send it into the impregnation machine under nitrogen pressure. The annealed electronic fiberglass cloth passes through the adhesive tank at a uniform speed, so that the surface of the monofilament is evenly coated with resin film. Then it enters the hot air oven to obtain a semi-cured sheet, which is rolled into a filament roll for later use.

[0015] S4: Cut the prepreg into sheets, stack two sheets together, cover the top and bottom with copper foil, and load them into a vacuum high-pressure press. First, raise the temperature and maintain the temperature to complete the low-pressure leveling. Then, raise the pressure to 1.0 MPa and simultaneously raise the temperature to 160°C at a rate of 1°C / min. Maintain this temperature for 30 minutes to allow the resin to enter the mid-to-late stage of cross-linking and the system to initially establish strength. Finally, complete the final curing. Then, cool the temperature to 60°C with cold water, release the pressure, and unload the board to obtain a high-transparency, low-expansion copper-clad laminate.

[0016] Furthermore, the epoxy-modified polysiloxane described in S1 has an epoxy equivalent of 3000~5000 g / eq.

[0017] Furthermore, the vacuum melting described in S2 requires vacuum melting at 140~150℃ for 25~35 minutes; the high-speed shearing to form a uniform slurry is set to a rotation speed of 2500~3500rpm and a time of 15~25 minutes; the gentle stirring takes 50~70 minutes.

[0018] Furthermore, in S3, the material passes through the glue tank at a constant speed of 3~5m / min, the tank temperature is 40~50℃, and the scraper gap is 0.10~0.15mm.

[0019] Furthermore, the heat preservation and low-pressure leveling described in S4 requires heat preservation for 8 to 15 minutes at a low pressure of 0.2 to 0.4 MPa; the final curing requires increasing the pressure to 2.0 to 3.0 MPa, while simultaneously increasing the temperature to 185 to 195°C at a uniform rate of 0.5 to 1.5°C / min.

[0020] Compared with the prior art, the present invention has the following beneficial effects: (1) High transparency and low haze: Through precise refractive index matching of core-shell particles and molecular-level enhancement of polyhedral oligomeric silsesquioxane, the main light scattering sources are eliminated, making it possible to achieve interlayer optical alignment and optical signal transmission of printed circuit boards.

[0021] (2) Low coefficient of thermal expansion and high dimensional stability: The rigid silica with high filling content and the polyhedral oligomeric silsesquioxane cage structure effectively restrict the thermal movement of polymer chain segments, greatly reducing thermal stress and warping risk during welding.

[0022] (3) Excellent dielectric properties: The low polarity of epoxy-modified polysiloxane, polyphenylene ether and hollow silica endows the material with low dielectric constant and ultra-low loss factor, which meets the millimeter-wave communication requirements of fifth-generation mobile communication technology.

[0023] (4) High resistance to damp heat: The benzoxazine-siloxane interface layer forms a highly cross-linked and strongly hydrophobic chemical bridging structure, which blocks the permeation path of water vapor along the filler interface, thereby greatly improving the stability of the material in damp heat environment. Attached Figure Description

[0024] Figure 1 This is a flowchart of a resin composition for high-transparency, low-expansion-coefficient copper-clad laminate, the copper-clad laminate, and its preparation method according to the present invention.

[0025] Figure 2 This is a schematic diagram of the synthesis route of the key components in the resin composition in Example 1 of the present invention.

[0026] Figure 3 This is the infrared spectrum verification diagram of the epoxy-modified polysiloxane in Example 1 of the present invention.

[0027] Figure 4 This is a comparison chart of the experimental results of transmittance, coefficient of thermal expansion, dielectric constant, loss factor, and peel strength in Experimental Example 1 of the present invention. Detailed Implementation

[0028] The following embodiments further explain and illustrate the technical solutions of the present invention. It should be specifically noted that each specific embodiment is a concretization and explanation of the technical solution and should not be considered as a limitation on the scope of protection of the present invention. Those skilled in the art still have the right to modify the technical solutions of these embodiments and make equivalent substitutions for some or all of the technical features, and these modifications or substitutions do not change the essence of the corresponding technical solutions, nor do they cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions described in the present invention.

[0029] This invention proposes a resin composition for high-transparency, low-expansion-coefficient copper-clad laminates, the copper-clad laminate itself, and a method for its preparation. Figure 1 The diagram shows a flowchart of a high-transparency, low-expansion-coefficient copper-clad laminate resin composition, the copper-clad laminate, and its preparation method according to the present invention. The detailed preparation steps are as follows: 1. Synthesis of key raw materials First, epoxy-modified polysiloxanes were synthesized via hydrosilylation reaction; simultaneously, benzoxazine-siloxane bifunctional interface compatibilizers were prepared via Mannich reaction and hydrosilylation reaction.

[0030] 2. Preparation of resin solution A two-step mixing process was employed. First, epoxy-modified polysiloxane, hydroxyl-terminated polyphenylene ether, and epoxy-based POSS resin matrix components were premixed at high temperature to obtain a homogeneous main mixture. Second, nanofillers and interfacial compatibilizers were dispersed at high speed in a partial solvent to form a uniform slurry. This slurry was then gently stirred and blended with the main resin mixture. Finally, an anhydride curing agent and an accelerator were added to obtain the final resin solution.

[0031] 3. Preparation of prepreg The above-mentioned resin solution is uniformly applied to the surface of the reinforcing material through processes such as impregnation and coating, and then pregelatinized in an oven to produce a semi-cured sheet.

[0032] 4. Copper-clad laminate pressing and molding Multilayer prepregs are laminated with metal foil and bonded using a three-stage heating and pressurizing curing process. This process sequentially includes a low-temperature, low-pressure leveling and wetting stage, a medium-temperature, medium-pressure preliminary cross-linking stage, and a high-temperature, high-pressure final curing stage. After cooling, a highly transparent, low-expansion copper-clad laminate is obtained.

[0033] The technical solution designed by this invention to solve the existing problems includes the following key points: 1. Epoxy-modified polysiloxane alkylates achieve synergistic effects of transparency and high-frequency performance. Traditional copper-clad laminate resins have highly polar molecular structures or strong crystallinity, resulting in intrinsic absorption or scattering in the visible light band, making it difficult to achieve high light transmittance. Furthermore, meeting high-frequency requirements often necessitates sacrificing mechanical strength, adhesion, or processability. Therefore, this invention constructs a high-performance resin system using epoxy-modified polysiloxane (EP-PDMS) as the optical and dielectric framework and hydroxyl-terminated polyphenylene ether (PPE) as a low-loss control and flame-retardant synergistic unit. Figure 2 As shown, the EP-PDMS backbone is a saturated siloxane backbone with extremely low polarizability and symmetrical molecular chains, exhibiting almost no intrinsic absorption in the visible light region, thus endowing the system with high light transmittance. Its flexible Si-O-Si segments are highly compatible with the phenylene ether units of PPE, and the two undergo a copolymerization reaction through a jointly added bridging curing agent, forming a uniform and dense three-dimensional cross-linked network. This reduces the dielectric constant and avoids phase separation light scattering. All components share the same curing system, forming a uniform and dense network through a one-step cross-linking process, with no small molecule precipitation. This ensures heat resistance while maintaining optical uniformity and low optical loss, achieving a transparent-low dielectric synergy.

[0034] 2. Balancing the contradiction between filling and light transmittance in a bifunctional interface agent and ternary filler system. Traditional high-filler composite materials require the addition of large amounts of rigid inorganic fillers to reduce the coefficient of thermal expansion. These fillers have a large refractive index difference with the resin matrix and are prone to agglomeration, resulting in severe light scattering and material devitrification, while also deteriorating the interface and increasing brittleness. This invention constructs a composite system with a bifunctional interfacial agent as a molecular bridge and three functionally complementary nanofillers as structural units, solving this problem through multi-layer synergistic effects. Specifically, it includes: epoxy polyhedral oligomeric silsesquioxane (POSS) as a nano-rigid framework, hollow SiO2 for introducing air cavities to reduce dielectric constant and coefficient of thermal expansion, and spherical molten SiO2 for optical cloaking through refractive index matching and toughening effect. The three are synergistically dispersed in the resin matrix through the anchoring effect of the benzoxazine-siloxane bifunctional interfacial compatibilizer, simultaneously achieving low expansion, low dielectric constant, and high light transmittance with a relatively low total filler content.

[0035] The filler-interface composite system of this invention achieves its function directly based on the molecular structure of the aforementioned polysiloxane resin system. This system achieves multi-level synergistic effects with the resin matrix through interfacial chemical bonding and filler property matching. First, the benzoxazine-siloxane bifunctional interfacial agent uses the resin system as the reactant: its benzoxazine end forms chemical bonds with the epoxy groups in the resin matrix through ring-opening copolymerization, while the siloxane end binds to the surface of the inorganic filler, thereby chemically anchoring the filler within the resin network. This enhances interfacial bonding while eliminating interfacial light scattering sources caused by weak physical bonding. Second, the functions of the three fillers are synergistic with the properties of the resin system: the epoxy group POSS participates in the resin cross-linking network through its epoxy functional groups, acting as a rigid nano-node to strengthen the overall structure and suppress thermal expansion; hollow SiO2 utilizes its air cavity to reduce the dielectric constant, creating a synergistic energy reduction effect with the low polarity of the resin itself; spherical molten SiO2, as rigid nano-reinforcing particles, primarily functions to improve the modulus, hardness, and heat resistance of the composite material, and reduce the coefficient of thermal expansion. Its spherical shape helps to disperse evenly in the resin, reducing stress concentration. In this way, the interface agent and filler system are deeply embedded and reinforce the resin matrix, together forming an integrated solution for achieving high transparency, low expansion, and low dielectric composite materials.

[0036] To analyze the composition of the resin composition of this invention, infrared spectroscopy characterization was performed. For example... Figure 3 As shown in the spectrum of the product, the product is located at ~1260 cm⁻¹. -1 and ~1000~1120cm -1 A strong and broad absorption band appears in the range, which is attributed to the symmetric deformation vibration of Si-CH3 and the stretching vibration of Si-O-Si bonds, respectively. This is a clear characteristic fingerprint peak of polysiloxane framework formation; at the same time, at ~1190 cm⁻¹... -1 The presence of COC stretching vibrations from the glycidyl ether structure further confirms the structure of the main chain and the introduced functional group fragments of the product. At ~1600 cm⁻¹ -1 With ~1470cm -1 The presence of a distinct aromatic ring skeletal vibration peak indicates that the synthesized product contains aromatic structures such as benzene rings, which is consistent with the design expectations. This result conclusively demonstrates that the present invention has successfully synthesized an organic-inorganic hybrid polymer with polysiloxane as the main chain and epoxy groups in the side chains. The ultra-low polarizability and chemical stability of the Si-O-Si bonds are the molecular structural basis for the high light transmittance, low dielectric constant, and excellent heat resistance of this polymer and its composites.

[0037] 3. Segmented and gentle composite process ensures stable molding of precision structures. Traditional copper clad laminate (CCL) manufacturing processes often employ a one-step high-speed mixing and high-temperature, high-pressure rapid lamination process, which easily leads to the rupture of hollow fillers and the aggregation of nanoparticles, damaging the microstructure and causing product performance fluctuations and low yield. This invention, however, employs a segmented, gentle process. In the adhesive preparation stage, the resin matrix is ​​first melt-blended under gentle conditions to form a stable prepolymer network. Subsequently, a uniformly dispersed nanofiller slurry is rapidly sheared in a low-boiling-point solvent and slowly introduced into the resin system under low-temperature, low-speed anchoring stirring conditions. This allows the functional filler to be fully impregnated and encapsulated by the resin. With the directional anchoring effect of the interfacial compatibilizer, a uniform and complete resin-filler microcomposite structure is initially constructed, while maximizing the protection of the integrity of the hollow filler and the dispersion of the nanoparticles.

[0038] During the lamination and curing stage, the resin system is first kept at a lower temperature and pressure. During this low-pressure leveling period, the resin system flows fully, eliminating microbubbles and completely impregnating the reinforcing fiberglass cloth, allowing the nanocomposite structure to arrange itself in an orderly manner in a relaxed state. Subsequently, a slow heating rate combined with segmented application of the final pressure guides the crosslinking reaction to proceed smoothly until complete curing at 190℃. This ensures uniform shrinkage and tight fusion of the multi-level structure from nano to macroscopic during the curing process, without internal stress concentration or structural damage.

[0039] Example 1 Table 1 Raw Material Information Table

[0040] A resin composition for high-transparency, low-expansion-coefficient copper-clad laminates, the copper-clad laminate itself, and a method for preparing the same, comprising the following steps: S1: In a reaction flask equipped with a stirrer, thermometer, and reflux condenser, add 100 parts of a solution of 1,3,5,7-tetrahydro-1,3,5,7-tetramethylcyclotetrasiloxane, 120 parts of allyl glycidyl ether, and 1 part by weight of chloroplatinic acid in isopropanol. Under nitrogen protection, stir at 90°C for 8 hours to carry out a hydrosilylation reaction. After the reaction is complete, dissolve the product in toluene, pour it into excess methanol to precipitate, filter, and dry the resulting solid under vacuum at 80°C for 12 hours to obtain a transparent solid, which is the epoxy-modified polysiloxane. Mix 100 parts of phenol, 45 parts of allylamine, 120 parts of paraformaldehyde, and 300 parts of toluene, and reflux at 110°C for 4 hours to generate an allyl-functionalized benzoxazine precursor. Then cool to 60°C, add 150 parts of a solution of hydrogen-containing silicone oil and 0.5 parts of chloroplatinic acid in isopropanol, and heat to 80°C for 6 hours. The solvent was removed by vacuum distillation, yielding a pale yellow viscous liquid, which is a benzoxazine-siloxane bifunctional interface compatibilizer.

[0041] S2: 50 parts of epoxy-modified polysiloxane, 18 parts of hydroxyl-terminated polyphenylene ether, and 4 parts of epoxy-based POSS are added to the reactor. After vacuum melting at 145℃ for 30 minutes, the mixture is cooled to 60℃ and discharged to obtain the main resin mixture, completing the first offline stage. The main mixture is transferred to a planetary reactor and kept at 50℃ with the anchor at 40 rpm. 20 parts of butanone solvent are used as a pre-dispersion carrier, and 8 parts of vinylsilane-modified hollow SiO2, 6 parts of spherical molten SiO2, and 1 part of benzoxazine-siloxane bifunctional interface compatibilizer are added sequentially. The mixture is first sheared at 3000 rpm for 20 minutes to prepare a uniform slurry. The slurry is then slowly poured into the planetary reactor and gently stirred with the main mixture for 60 minutes. Finally, 8.5 parts of methylhexacyanamide and 0.3 parts of N,N-dimethylbenzylamine are added, and the mixture is stirred at 30 rpm for 15 minutes to obtain the final adhesive solution.

[0042] S3: Transfer the adhesive solution into a constant temperature pressure tank, and feed it into the impregnation machine under nitrogen pressure of 0.2MPa. 20μm annealed electronic glass fiber cloth passes through the adhesive tank at a uniform speed of 4m / min. The tank temperature is 45℃ and the gap between the scrapers is 0.12mm, so that the surface of the monofilament is evenly coated with resin film. Then it enters the zone 5 hot air oven and stays for 4 minutes to obtain a semi-cured sheet with a gelation time of 135 seconds and an adhesive content of 52%. Roll it into a 300mm diameter filament roll for later use.

[0043] S4: The semi-cured sheet containing nanofillers is cut into 410mm×510mm sheets, two sheets are stacked together, and 12μm RTF copper foil is applied to both the top and bottom. The sheets are then placed in a vacuum high-pressure press. First, the temperature is raised to 120℃ at 2℃ / min and held at 0.3MPa for 10 minutes to complete low-pressure leveling. Then, the pressure is increased to 1.0MPa, and the temperature is raised to 160℃ at a rate of 1℃ / min. The temperature is held at this condition for 30 minutes to allow the resin to enter the mid-to-late stage of cross-linking and the system to initially establish strength. Finally, the pressure is increased to 2.5MPa, and the temperature is raised to 190℃ at a rate of 1℃ / min. The temperature is held at this condition for 120 minutes to complete the final curing. Then, cold water is circulated to cool the temperature to 60℃, the pressure is released, and the sheet is unloaded to obtain a high-transparency, low-expansion copper-clad laminate with a thickness of 0.1mm.

[0044] Example 2 The preparation method is the same as in Example 1, except that: S1: Replace 120 parts allyl glycidyl ether and 1 part isopropanol chloroplatinate solution with 90 parts allyl glycidyl ether and 0.5 parts isopropanol chloroplatinate solution; S2: 50 parts epoxy-modified polysiloxane and 18 parts hydroxyl-terminated polyphenylene ether were replaced with 48 parts epoxy-modified polysiloxane and 16 parts hydroxyl-terminated polyphenylene ether; 4 parts epoxy-based POSS were replaced with 3 parts epoxy-based POSS; vacuum melting at 145°C for 30 minutes was replaced with vacuum melting at 140°C for 25 minutes; 8 parts vinylsilane-modified hollow SiO2, 6 parts spherical molten SiO2 and 1 part benzoxazine-siloxane bifunctional interface compatibilizer were replaced with 6 parts vinylsilane-modified hollow SiO2, 4 parts spherical molten SiO2 and 0.5 parts benzoxazine-siloxane bifunctional interface compatibilizer; high-speed shearing at 3000 rpm for 20 minutes was replaced with high-speed shearing at 2500 rpm for 15 minutes; gentle stirring with the main mixture for 60 minutes was replaced with gentle stirring with the main mixture for 50 minutes. S3: Passing through the glue tank at a constant speed of 4m / min, with a tank temperature of 45℃ and a scraper gap of 0.12mm is replaced with passing through the glue tank at a constant speed of 3m / min, with a tank temperature of 40℃ and a scraper gap of 0.10mm. S4: Replace the 0.3MPa holding time for 10 minutes with the 0.2MPa holding time for 8 minutes; then increase the pressure to 2.5MPa and heat to 190℃ at a rate of 1℃ / min, instead of increasing the pressure to 2.0MPa and heating to 185℃ at a rate of 0.5℃ / min. All other steps are the same.

[0045] Example 3 The preparation method is the same as in Example 1, except that: S1: Replace 120 parts allyl glycidyl ether and 1 part isopropanol chloroplatinate solution with 130 parts allyl glycidyl ether and 2 parts isopropanol chloroplatinate solution; S2: 50 parts epoxy-modified polysiloxane and 18 parts hydroxyl-terminated polyphenylene ether were replaced with 52 parts epoxy-modified polysiloxane and 20 parts hydroxyl-terminated polyphenylene ether; 4 parts epoxy-based POSS were replaced with 5 parts epoxy-based POSS; vacuum melting at 145°C for 30 minutes was replaced with vacuum melting at 150°C for 35 minutes; 8 parts vinylsilane-modified hollow SiO2, 6 parts spherical molten SiO2 and 1 part benzoxazine-siloxane bifunctional interface compatibilizer were replaced with 10 parts vinylsilane-modified hollow SiO2, 8 parts spherical molten SiO2 and 1.5 parts benzoxazine-siloxane bifunctional interface compatibilizer; high-speed shearing at 3000 rpm for 20 minutes was replaced with high-speed shearing at 3500 rpm for 25 minutes; gentle stirring with the main mixture for 60 minutes was replaced with gentle stirring with the main mixture for 80 minutes. S3: Passing through the glue tank at a constant speed of 4m / min, with a tank temperature of 45℃ and a scraper gap of 0.12mm is replaced with passing through the glue tank at a constant speed of 5m / min, with a tank temperature of 50℃ and a scraper gap of 0.15mm. S4: Replace 0.3MPa holding time for 10 minutes with 0.4MPa holding time for 15 minutes; then increase the pressure to 2.5MPa and heat to 190℃ at a rate of 1℃ / min; replace with increasing the pressure to 3.0MPa and heating to 195℃ at a rate of 1.5℃ / min. All other steps are the same.

[0046] Comparative Example 1 S2: Replace the resin combination of 50 parts epoxy-modified polysiloxane and 18 parts hydroxyl-terminated polyphenylene ether with an equal amount of 68 parts standard bisphenol A type epoxy resin. All other steps are the same.

[0047] Comparative Example 2 S2: Omit the step of adding 1 part of benzoxazine-siloxane bifunctional interface compatibilizer, and replace 8 parts of vinylsilane modified hollow SiO2 and 6 parts of spherical molten SiO2 with 14 parts of ordinary solid SiO2 micro powder of the same particle size. All other steps are the same.

[0048] Comparative Example 3 Using the exact same raw materials and proportions as in Example 1, but with a different preparation process: the segmented steps of first preparing the resin main mixture and then slowly and gently introducing the filler slurry, as in Example 1, are omitted. Instead, all resin, filler, additives, and solvents are added to the reactor at once and mixed at high speed (3000 rpm) for 60 minutes at room temperature to prepare the adhesive. Simultaneously, the procedure of first low-pressure leveling and then segmented pressure increase, as in Example 1, is omitted. Instead, a final pressure of 2.5 MPa is applied directly after lamination, and the temperature is rapidly increased to 190°C at a rate of 5°C / min and held for curing for 120 minutes.

[0049] All other steps are the same.

[0050] Experimental Example 1 The prepregs prepared in step S3 of Examples 1-3 and Comparative Examples 1-3, and the copper-clad laminates prepared in step S4 were measured: (1) Transmittance: Referring to GB / T 2410-2022 "Plastics—Determination of transmittance and haze", the prepreg was first cleaned with anhydrous ethanol and dried, then cut into 50mm×50mm samples. Using a UV-Vis spectrophotometer equipped with an integrating sphere, the luminous flux transmitted through a 0.10±0.02mm thick substrate was measured under perpendicular incidence of 550nm monochromatic light. The ratio of the luminous flux to that of the air reference was the transmittance value. To obtain reliable data, at least 5 parallel samples were tested for each group, and the average value was taken.

[0051] (2) Coefficient of thermal expansion: The prepreg was cut into strips 20 mm long and 5 mm wide along the mechanical direction and placed in the sample holder of the thermomechanical analyzer. A constant light load of 0.05 N was applied to prevent the sample from bending. The temperature was increased from room temperature to 300 °C at a rate of 5 °C / min, and the instrument probe monitored the change in sample length in real time. The dimensional change data in the temperature range of 50~150 °C were collected, and the average linear coefficient of thermal expansion (α) in this temperature range was automatically calculated by the software. The calculation formula is α=ΔL / (L0·ΔT). The result is expressed in ppm / °C, and the instrument resolution can reach 0.1 ppm / °C. At least 5 samples should be tested in each group, and the average value of the results should be taken.

[0052] (3) Dielectric constant (Dk) and loss factor (Df): Using a vector network analyzer with a cylindrical resonant cavity, the prepreg was precisely cut into 15mm × 15mm square samples that matched the electric field distribution of the resonant cavity. The cavity resonant frequency (f0) and quality factor (Q0) were first calibrated and recorded, and then the frequency shift (Δf) and Q-value change (ΔQ) were measured by inserting the sample. The result was calculated using the formula: Dk≈1 + (V c / V s )·(Δf / f0)Df≈(V c / 2V s )·(1 / Qm-1 / Q0), where V c V s These are the cavity volume and the sample volume, respectively. Each sample needs to be rotated 90° and measured twice, with the average value taken. To obtain reliable data, at least 5 parallel samples should be tested in each group, and the results should be averaged.

[0053] (4) Peel strength: A 3mm wide and 100mm long copper foil line was etched onto the copper-clad laminate, and the remaining copper foil was completely removed with etching solution. The copper foil was peeled off using a special fixture at a 90° vertical angle and a constant speed of 50mm / min, and the peel force curve was recorded in real time by the testing machine. The average force value in the middle 50mm section of the peel stroke was taken and divided by the width of the copper foil to obtain the peel strength value, in N / mm. Five parallel tests were conducted on each sample and the average value was taken.

[0054] Table 2 Comparison of experimental results of Examples 1-3 and Comparative Examples 1-3

[0055] The experimental results of Examples 1-3 and Comparative Examples 1-3 are shown in Table 2 and Figure 4 As shown, the copper-clad laminate produced by the present invention achieves the best synergistic and comprehensive performance balance of high transparency, low thermal expansion, excellent high frequency performance and high reliability under the conditions of Example 1. Therefore, Example 1 is the best implementation point of the present invention.

[0056] The overall performance degradation of Example 2 stemmed from the dual reduction in the amount of key components and the intensity of the process. The reduction in epoxy-modified polysiloxane, polyphenylene ether, and functional fillers weakened the material's intrinsic low dielectric properties, enhanced rigidity, and thermal expansion suppression efficiency. Simultaneously, the reduction in process parameters affected the integrity of filler dispersion and interfacial bonding. This resulted in a decrease in transmittance, dimensional stability, and high-frequency electrical properties compared to Example 1. Example 3, however, exhibited performance differentiation. While increasing the rigidity of the components and the intensity of the process further optimized the coefficient of thermal expansion and dielectric loss, a trade-off occurred between transmittance and peel strength. This indicates that while increasing component concentration and process parameters can improve specific indicators, it can also lead to a negative correlation between optical performance and interfacial mechanical reliability. This confirms the inherent constraints between different performance parameters, necessitating systematic and synergistic optimization through precise formulation and process design.

[0057] Due to the lack of key technologies, the overall performance of Comparative Examples 1-3 was reduced to varying degrees compared to the Examples. In Comparative Example 1, after replacing the resin system of the present invention with conventional bisphenol A epoxy, the performance deteriorated significantly and comprehensively. Its light transmittance decreased to 41.85%, high-frequency performance deteriorated, and the coefficient of thermal expansion increased to 18.29 ppm / ℃. This result proves that it is impossible to achieve both high light transmittance and low dielectric loss using traditional high-polarity epoxy resins, while also being difficult to balance low thermal expansion and inherent flame retardancy. This comparison verifies the key role of the epoxy-modified polysiloxane, polyphenylene ether, and phosphorus-containing epoxy synergistic resin system in the present invention. In Comparative Example 2, after omitting the interface compatibilizer and replacing the functional filler with ordinary solid SiO2, its light transmittance, peel strength, and high-frequency performance all showed significant deterioration. This indicates that without the bridging effect of the benzoxazine-siloxane bifunctional interfacial agent, the interfacial bonding force between the inorganic filler and the resin matrix will be severely insufficient, directly leading to a decrease in mechanical reliability. Furthermore, without hollow-structured fillers and core-shell particles with matching refractive indices, conventional solid fillers alone cannot maintain high light transmittance at high filler volumes, nor can they achieve efficient thermal expansion control and low dielectric properties. Comparative Example 3, using a traditional vigorous process while maintaining the exact same formulation, showed varying degrees of decline in its various properties. The increase in the coefficient of thermal expansion and dielectric loss was particularly significant, directly confirming the damage to the hollow filler structure and the filler-resin interface caused by the traditional process, directly weakening its core functions of reducing expansion and loss. The relatively smaller decrease in light transmittance and peel strength indicates that the optical and mechanical performance framework provided by the basic formulation was partially preserved.

[0058] In summary, this invention utilizes epoxy-modified polysiloxane as the main resin, synergistically combining specific nanofillers and bifunctional interface agents to construct a composite system, and achieves curing and molding through a segmented and mild process. This results in a copper-clad laminate that maintains high light transmittance while also possessing a low coefficient of thermal expansion, excellent high-frequency dielectric properties, and reliable interfacial bonding strength, making it suitable for advanced electronic packaging fields with stringent requirements for both optical and electrical performance.

Claims

1. A resin composition for copper-clad laminates with high transparency and low coefficient of expansion, characterized in that, Based on epoxy-modified polysiloxane, it is composed of the following components: 48-52 parts epoxy-modified polysiloxane, 16-20 parts hydroxyl-terminated polyphenylene ether, 8.5 parts methyl hexacyanamide, 3-5 parts epoxy polyhedral oligomeric silsesquioxane, 6-10 parts vinylsilane-modified hollow SiO2, 4-8 parts spherical molten SiO2, 0.5-1.5 parts benzoxazine-siloxane bifunctional interface compatibilizer, 0.3 parts N,N-dimethylbenzylamine, and 20 parts butanone solvent.

2. The resin composition for high transparency and low coefficient of thermal expansion copper clad laminates as described in claim 1, characterized in that, The epoxy-modified polysiloxane is a polydimethylsiloxane with epoxy propoxy groups in the side chain, having a number-average molecular weight of 3000-8000 and an epoxy equivalent of 3000-5000 g / eq, and the epoxy groups are connected to the siloxane backbone through C3 alkoxy bridges.

3. The resin composition for high transparency and low coefficient of thermal expansion copper clad laminates as described in claim 1, characterized in that, The spherical molten SiO2 is a spherical amorphous SiO2 surface-treated with vinylsilane, with an average particle size of 0.5~2μm, a sphericity ≥95%, and a refractive index of 1.45~1.

46. Its surface forms Si-SC covalent bonds with the resin matrix through a thiol-epoxy click reaction.

4. The resin composition for high transparency and low coefficient of thermal expansion copper clad laminate as described in claim 1, characterized in that, The benzoxazine-siloxane bifunctional interface compatibilizer is a compound containing both a benzoxazine ring and a siloxane segment, wherein the hydrogen content of the siloxane segment is 0.1~1.0wt%.

5. A method for preparing a resin composition for high transparency and low coefficient of thermal expansion copper clad laminates according to any one of claims 1 to 4, characterized in that, Includes the following steps: S1: 1,3,5,7-Tetrahydro-1,3,5,7-tetramethylcyclotetrasiloxane, allyl glycidyl ether, and isopropanol chloroplatinate solution were reacted under nitrogen protection with stirring. After the reaction was completed, the product was dissolved in toluene, poured into excess methanol to precipitate, filtered, and vacuum dried to obtain epoxy-modified polysiloxane for later use. Phenol, allylamine, paraformaldehyde, and toluene were mixed and refluxed to generate an allyl-functionalized benzoxazine precursor. Then, the temperature was lowered and hydrogen-containing silicone oil and isopropanol chloroplatinate solution were added, followed by heating and reaction. The solvent was removed by vacuum distillation to obtain a benzoxazine-siloxane bifunctional interface compatibilizer for later use. S2: After vacuum melting of epoxy-modified polysiloxane, hydroxyl-terminated polyphenylene ether, and epoxy-based polyhedral oligomeric silsesquioxane, the mixture is cooled and discharged to obtain the main mixture. The main mixture is then kept at 50°C and the anchor is set at 40 rpm. Butanone solvent is used as a pre-dispersion carrier, and vinylsilane-modified hollow SiO2, spherical molten SiO2, and benzoxazine-siloxane bifunctional interface compatibilizer are added sequentially. The mixture is first sheared at high speed to form a uniform slurry. The slurry is then gently stirred with the main mixture, and finally methyl hexacyanamide and N,N-dimethylbenzylamine are added. The mixture is stirred at high speed to obtain the final adhesive solution.

6. The method for preparing a resin composition for high-transparency, low-expansion-coefficient copper-clad laminate as described in claim 5, characterized in that, The vacuum melting described in S2 requires vacuum melting at 140~150℃ for 25~35 minutes; the high-speed shearing to form a uniform slurry is set to a rotation speed of 2500~3500rpm and a time of 15~25 minutes; the gentle stirring is carried out for 50~70 minutes.

7. The high-transparency, low-expansion-coefficient copper-clad laminate as described in claim 5, characterized in that, The copper clad laminate includes at least one insulating layer reinforced with ultra-thin open-fiber electronic-grade glass fiber cloth, the insulating layer being formed by impregnation and curing of the resin composition; and an RTF copper foil laminated on at least one surface of the insulating layer.

8. The high-transparency, low-expansion-coefficient copper-clad laminate as described in claim 7, characterized in that, The copper-clad laminate preparation method is as follows: the adhesive solution is fed into the impregnation machine under nitrogen pressure, and the annealed electronic fiberglass cloth passes through the adhesive tank at a uniform speed; then it is dried to obtain a semi-cured sheet, which is rolled into a filament roll for later use; the semi-cured sheet is cut into sheets, two sheets are stacked together, copper foil is applied to the top and bottom, and after being cured by vacuum hot pressing, a high-transparency, low-expansion copper-clad laminate product is obtained.

9. The high-transparency, low-expansion-coefficient copper-clad laminate as described in claim 8, characterized in that, The uniform speed through the glue tank is 3~5m / min, the tank temperature is 40~50℃, and the scraper gap is 0.10~0.15mm.

10. The high-transparency, low-expansion-coefficient copper-clad laminate as described in claim 8, characterized in that, The vacuum hot pressing process requires holding at a low pressure of 0.2~0.4MPa for 8~15 minutes to complete low-pressure leveling. Then, the pressure is increased to 1.0MPa, and the temperature is increased to 160℃ at a rate of 1℃ / min. This temperature is then maintained for 30 minutes to allow the resin to enter the mid-to-late stage of crosslinking, and the system initially establishes strength. Finally, the pressure is increased to 2.0~3.0MPa, and the temperature is increased uniformly at a rate of 0.5~1.5℃ / min to 185~195℃ and maintained.

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