Composite dielectric sheet fabric and preparation method thereof

Abstract

The invention discloses a composite dielectric sheet fabric and a preparation method thereof, a preparation method of a circuit board and a flip chip ball grid array packaging structure. The composite dielectric sheet fabric comprises film-forming resin, a metal layer, a metal layer and a metal layer, wherein the film-forming resin comprises a polymer containing an aromatic heterocyclic ring main chain; a binder resin including an epoxy resin and a cured resin; the dielectric modified resin comprises at least one of polyphenyl ether resin, bismaleimide resin, benzoxazine resin and hydrocarbon resin; the surface of the inorganic filler is modified by one or more functional groups selected from the following groups: anilino, alkyl, functional groups containing nitrogen on a main chain or a branched chain, functional groups containing double bonds and epoxy groups. According to the composite dielectric sheet fabric, ultralow dielectric loss is achieved, meanwhile, the composite dielectric sheet fabric has high adhesive force to low-polarity substrates (M8, M9, PTFE, glass and ceramic substrates), high bonding strength with a metal circuit can be guaranteed under low surface roughness, and the transmission quality of high-frequency signals and the long-term reliability of the circuit are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of electronic materials technology, and in particular to a composite dielectric sheet material and its preparation method, a circuit board preparation method, and a flip-chip ball grid array packaging structure. Background Technology

[0002] With the rapid development of 5G / 6G communications, artificial intelligence (AI), and high-performance computing, semiconductor packaging technology is evolving towards miniaturization, multifunctionality, and high density. Against this backdrop, flip-chip ball grid array (FCBGA) packaging substrates, due to their ability to enable high-speed and multifunctional chips, have become a core packaging solution for central processing units (CPUs), graphics processing units (GPUs), and high-end servers. In the manufacturing process of such high-density packaging substrates, build-up film, as a key material in the semi-additive process (SAP), directly determines the electrical characteristics and reliability of the final product. Currently, epoxy resin-based build-up films, such as Ajinomoto's ABF series, are the mainstream technology widely used in the industry.

[0003] However, with the continuous increase in signal transmission frequency, existing epoxy resin-based multilayer films have gradually revealed their inherent technical defects. Firstly, regarding dielectric properties, traditional epoxy resin-based materials, due to the presence of numerous polar groups in their molecular structure, exhibit high dielectric loss (Df) at high frequencies. For example, the commercially available ABF / GCP product GXT31GCP has a Df value between 0.013 and 0.014. Applying it to low-loss substrates such as MEGTRON 8 (M8) would actually degrade the high-frequency characteristics of the entire composite substrate. Secondly, in terms of material compatibility, existing multilayer films based on highly polar epoxy resins have a natural polarity difference with high-performance substrates such as M8 that use low-polarity hydrocarbon resins, resulting in insufficient adhesion between the two and a risk of delamination failure. In addition, in order to ensure the adhesion of the subsequent chemical copper plating layer, the superadditive plating (SAP) process usually requires a desmearing process on the dielectric layer surface. However, this increases the surface roughness of the circuit, which in turn causes additional signal transmission loss due to the skin effect, limiting the performance of ultra-fine lines (such as L / S = 2 / 2 μm) in high-frequency and high-speed applications.

[0004] In summary, existing technologies struggle to simultaneously meet the stringent requirements of future electronic products, including ultra-low dielectric loss, excellent adhesion to heterogeneous materials, low coefficient of thermal expansion, and support for precision circuit manufacturing with low surface roughness. Therefore, developing a novel composite dielectric material that not only possesses superior high-frequency dielectric properties but also bonds firmly to various substrates (especially low-polarity substrates) and is compatible with advanced circuit manufacturing processes that do not require excessive surface roughening has become a pressing technical challenge for those skilled in the art. Summary of the Invention

[0005] The main objective of this invention is to propose a composite dielectric sheet material, which aims to solve the technical problems of high high-frequency dielectric loss, poor adhesion to low polarity substrates, and difficulty in achieving both low surface roughness and high circuit bonding strength in existing dielectric materials.

[0006] To achieve the above objectives, the composite dielectric sheet fabric proposed in this invention comprises a polymer resin and inorganic fillers, wherein,

[0007] The polymer resin includes:

[0008] A film-forming resin, wherein the film-forming resin comprises a polymer with an aromatic heterocyclic backbone;

[0009] The adhesive resin comprises an epoxy resin and a curing resin; and

[0010] The dielectric modified resin comprises at least one of polyphenylene ether resin, bismaleimide resin, benzoxazine resin and hydrocarbon resin.

[0011] The surface of the inorganic filler is modified with one or more functional groups selected from the group consisting of aniline, alkyl, nitrogen-containing functional groups on the main chain or branches, double-bonded functional groups, and epoxy groups.

[0012] In one embodiment, the polymer comprising an aromatic heterocyclic backbone is selected from at least one of polyimide, modified polyimide, and modified bismaleimide.

[0013] In one embodiment, the polyimide includes at least one of liquid polyimide and thermoplastic polyimide.

[0014] In one embodiment, the epoxy resin is selected from at least one of glycidylamine epoxy resin, polyfunctional o-cresol glycidyl ether epoxy resin, phenol-biphenyl epoxy resin, bisphenol F solid epoxy resin, isocyanate modified epoxy resin, naphthol epoxy resin, and phenol-formaldehyde epoxy resin.

[0015] In one embodiment, the cured resin comprises a phenolic resin selected from at least one of linear phenol-formaldehyde resin and linear BPA-formaldehyde resin.

[0016] In one embodiment, the cured resin is further selected from at least one of benzoxazine, bismaleimide resin, reactive ester, and amine dicyandiamide curing agent.

[0017] In one embodiment, the content of the phenolic resin and the content of the epoxy resin satisfy the following formula:

[0018] Phenolic resin content = (hydroxyl equivalent of phenolic resin / epoxy equivalent of epoxy resin) × epoxy resin content.

[0019] In one embodiment, the bonding resin further comprises a flowability adjusting resin selected from at least one of semi-crystalline epoxy resin, liquid bisphenol A type epoxy resin, liquid bisphenol F type epoxy resin, liquid bisphenol A-bisphenol F composite epoxy resin, liquid bisphenol S epoxy resin, liquid phenolic epoxy resin, and liquid phenolic resin.

[0020] In one embodiment, the flowability adjusting resin accounts for no more than 50% by weight of the binding resin.

[0021] In one embodiment, the hydrocarbon resin is a polyfunctional vinyl aromatic copolymer.

[0022] In one embodiment, the hydrocarbon resin comprises a modified hydrocarbon resin; and / or

[0023] The bismaleimide resin includes modified bismaleimide; and / or

[0024] The benzoxazine includes modified benzoxazine.

[0025] In one embodiment, the modified bismaleimide comprises a polyimide-modified bismaleimide.

[0026] In one embodiment, the inorganic filler is selected from at least one of silica, hollow silica, nano-silica derived from polyhedral oligomeric silsesquioxanes, boron nitride, perfluoroalkoxyalkane, and polytetrafluoroethylene.

[0027] In one embodiment, the composite dielectric sheet fabric comprises, by weight percentage:

[0028] 15% to 70% of the aforementioned polymeric resin; and

[0029] The inorganic filler comprises 30% to 85%.

[0030] In one embodiment, the polymer resin comprises, by weight percentage:

[0031] 5% to 60% of the adhesive resin;

[0032] 40% to 85% of the film-forming resin; and

[0033] 1% to 55% of the dielectric-modified resin.

[0034] In one embodiment, the composite dielectric sheet fabric further includes an additive selected from at least one of leveling agents, dispersants, and defoamers.

[0035] In one embodiment, the composite dielectric sheet fabric further includes a solvent selected from at least one of water, N-methylpyrrolidone, ethanol, acetone, ethyl acetate, n-butyl ether, methyl tert-butyl ether, dimethyl phthalate, butanone, dimethyl sulfoxide, n-butyl ketone, cyclohexanone, toluene, and xylene.

[0036] The present invention also provides a method for preparing a composite dielectric sheet fabric, used to prepare the composite dielectric sheet fabric described in any of the preceding claims, the preparation method comprising the following steps:

[0037] Preparation of resin slurry: The film-forming resin, the bonding resin and the dielectric modified resin are mixed in a first solvent to obtain a resin slurry;

[0038] Preparation of filler slurry: The inorganic filler is mixed in a second solvent to obtain a filler slurry; and

[0039] Mixing: The filler slurry is added to the resin slurry being stirred and mixed to obtain a resin composition containing the polymer resin and the inorganic filler.

[0040] In one embodiment, in the step of preparing the resin slurry, at least one additive selected from dispersants, defoamers, and leveling agents is pre-added to the first solvent; and / or

[0041] In the step of preparing the filler slurry, at least one additive selected from dispersants, defoamers and leveling agents is pre-added to the second solvent.

[0042] In one embodiment, the mixing conditions of the preparation method include at least one of the following:

[0043] The mixing speed during the preparation of the resin slurry is between 3600 rpm and 7200 rpm, the slurry temperature is not higher than 45°C, and the duration is between 60 and 120 minutes.

[0044] The mixing speed during the preparation of the filler slurry is between 3600 rpm and 7200 rpm, the slurry temperature is not higher than 45°C, and the duration is between 60 and 120 minutes; and

[0045] The mixing speed of the filler slurry and the resin slurry is between 3600 rpm and 7200 rpm, the slurry temperature is not higher than 45°C, and the duration is between 60 and 120 minutes.

[0046] In one embodiment, after the mixing step, the preparation method further includes the following steps:

[0047] Solvent removal: The composite dielectric sheet fabric mixture is subjected to solvent removal treatment to obtain a composite dielectric sheet fabric ink with a solid content between 64% and 98% and a viscosity between 10000 Pa·s and 50000 mPa·s.

[0048] In one embodiment, the solvent removal process includes: continuously stirring the composite dielectric sheet fabric mixing slurry for 5 minutes to 3 hours at a temperature of 20°C to 50°C and a vacuum environment with a vacuum degree of less than 0.1 MPa.

[0049] In one embodiment, after the solvent removal step, the preparation method further includes the following steps:

[0050] Preparation of dry film: The composite dielectric sheet fabric ink is coated onto the substrate film and then cured to obtain the composite dielectric sheet fabric dry film.

[0051] In one embodiment, the curing process includes drying the composite dielectric sheet fabric ink at a temperature range of 50°C to 120°C for 30 seconds to 30 minutes.

[0052] This invention also provides a method for manufacturing a circuit board, comprising the following steps:

[0053] Provide substrate: Provide a circuit board substrate with the area to be added;

[0054] Applying composite dielectric sheet fabric: Applying the composite dielectric sheet fabric as described in any one of claims 1 to 17 to the region of the circuit board substrate to be added to form an added structure;

[0055] Surface treatment: The added-layer structure is subjected to surface treatment so that the surface roughness Ra of the added-layer structure is not greater than 0.2 μm and Rz is not greater than 4 μm;

[0056] Metallization: Metal lines are fabricated on the surface of the added-layer structure.

[0057] In one embodiment, when using composite dielectric sheet fabric ink, the step of applying the composite dielectric sheet fabric includes:

[0058] Preparation of dry film: The composite dielectric sheet fabric ink is coated on a carrier and dried at a temperature range of 50°C to 120°C for 30 seconds to 30 minutes to obtain a composite dielectric sheet fabric dry film, wherein the carrier is a substrate film or a copper foil layer.

[0059] Bonding: The composite dielectric sheet dry film is hot-pressed onto the circuit board substrate at a temperature range of 50°C to 150°C and maintained for 30 seconds to 30 minutes; and

[0060] Curing: The composite dielectric sheet is cured on the circuit board substrate at a temperature range of 120°C to 250°C for 10 minutes to 5 hours to form the added-layer structure.

[0061] In one embodiment, when using a composite dielectric sheet dry film, the step of applying the composite dielectric sheet includes:

[0062] Bonding: The composite dielectric sheet dry film is hot-pressed onto the circuit board substrate at a temperature range of 50°C to 150°C and maintained for 30 seconds to 30 minutes; and

[0063] Curing: The composite dielectric sheet is cured on the circuit board substrate at a temperature range of 120°C to 250°C for 10 minutes to 5 hours to form the added-layer structure.

[0064] In one embodiment, prior to performing the surface treatment step, the preparation method further includes:

[0065] Carrier removal: Remove the carrier from the surface of the dry film of the composite dielectric sheet. When the carrier is a substrate film, it is removed by peeling. When the carrier is a copper foil layer, it is removed by etching.

[0066] In one embodiment, the pull-out force between the metal wires formed in the metallization step and the added-layer structure is not less than 5 N / cm.

[0067] The present invention also provides a method for manufacturing a circuit board, comprising the following steps: providing a substrate: providing a circuit board substrate having a drilling area;

[0068] Applying composite dielectric sheet fabric: Applying the composite dielectric sheet fabric as described in any one of claims 1 to 17 to the area to be drilled on the circuit board substrate to form a dielectric layer;

[0069] Drilling: Hole structures are formed on the circuit board substrate and the dielectric layer by means of laser drilling or mechanical drilling;

[0070] Adhesive removal: The hole structure is subjected to adhesive removal treatment to modify the edges of the hole structure and remove drilling residue;

[0071] Metallization process: The surfaces of the hole structure and the dielectric layer after the adhesive removal process are metallized to form metal lines on the hole walls of the hole structure and the surface of the dielectric layer.

[0072] In one embodiment, when using composite dielectric sheet fabric ink, the step of applying the composite dielectric sheet fabric includes:

[0073] Preparation of dry film: The composite dielectric sheet fabric ink is coated on a carrier and dried at a temperature range of 50°C to 120°C for 30 seconds to 30 minutes to obtain a composite dielectric sheet fabric dry film, wherein the carrier is a substrate film or a copper foil layer.

[0074] Bonding: The composite dielectric sheet dry film is hot-pressed onto the circuit board substrate at a temperature range of 50°C to 150°C and maintained for 30 seconds to 30 minutes; and

[0075] Curing: The composite dielectric sheet is cured on the circuit board substrate at a temperature range of 120°C to 250°C for 10 minutes to 5 hours to form the added-layer structure.

[0076] In one embodiment, when using a composite dielectric sheet dry film, the step of applying the composite dielectric sheet includes:

[0077] Bonding: The composite dielectric sheet dry film is hot-pressed onto the circuit board substrate at a temperature range of 50°C to 150°C and maintained for 30 seconds to 30 minutes; and

[0078] Curing: The composite dielectric sheet is cured on the circuit board substrate at a temperature range of 120°C to 250°C for 10 minutes to 5 hours to form the added-layer structure.

[0079] In one embodiment, prior to performing the drilling step, the preparation method further includes:

[0080] Carrier removal: Remove the carrier from the surface of the dry film of the composite dielectric sheet. When the carrier is a substrate film, it is removed by peeling. When the carrier is a copper foil layer, it is removed by etching.

[0081] In one embodiment, after the adhesive removal process, the surface roughness Ra of the dielectric layer is no greater than 0.2 μm and Rz is no greater than 4 μm.

[0082] In one embodiment, the peel strength between the metal line formed in the metallization step and the dielectric layer is not less than 5 N / cm.

[0083] The present invention also provides a flip-chip ball grid array packaging structure, including a core layer and a stacked structure disposed on the core layer, wherein the stacked structure includes a dielectric layer formed by curing a composite dielectric sheet material as described in any of the preceding claims, and the dielectric layer is configured as a build-up material, a buried capacitor material, or a via-filling resin.

[0084] The composite dielectric sheet fabric proposed in this application has the following beneficial effects:

[0085] 1. Achieves superior high-frequency, low-loss dielectric properties and enhances substrate grade:

[0086] Dielectrically modified resins (such as hydrocarbon resins) have extremely low molecular polarity, fundamentally reducing polarization loss in high-frequency electric fields. Simultaneously, surface-modified inorganic fillers, particularly those with inherently low dielectric loss (such as PTFE), form a low-polarity synergistic composite system with the resin matrix. This low-loss characteristic directly reduces energy attenuation during high-frequency signal transmission, crucial for ensuring signal integrity. Therefore, by introducing dielectrically modified resins and inorganic fillers, the composite dielectric sheet fabric of this invention exhibits extremely low dielectric constant (Dk between 3.0 and 3.3, or even below 3.0) and dielectric loss (Df between 0.0015 and 0.0025, or even below 0.0015) at high frequencies (e.g., 10 GHz) after curing. Thus, when the composite dielectric sheet fabric is applied to traditional substrates (such as epoxy fiberglass cloth substrates, M8-M10 substrates, glass and ceramic substrates), it can significantly improve and enhance the surface dielectric properties of the traditional substrates. Its superior performance can even elevate the overall characteristics of ordinary epoxy fiberglass cloth substrates (FR4) with poor dielectric loss to the level of expensive M8 materials.

[0087] 2. Possesses excellent cross-material adhesion and interfacial compatibility:

[0088] The bonding resins (including phenolic resins and epoxy resins) can form strong chemical bonds or physical adsorption with the surfaces of different substrates. Simultaneously, the robust framework provided by the film-forming resin (such as PI / BMI) enhances interfacial stability. More importantly, the specific functional group modification of the inorganic filler surface (such as aniline, alkyl, nitrogen-containing functional groups, epoxy groups, etc.) acts as a bridge, enabling strong interactions with both the polymer resin matrix and the substrate surface. Therefore, through the synergistic effect of the bonding resins, film-forming resins, and surface-modified inorganic fillers, the composite dielectric sheet fabric of this invention exhibits excellent adhesion to various substrates, particularly with ceramic and glass substrates where the adhesion is greater than 10 N / cm, and with copper even at low surface roughness (Ra < 0.2 μm, Rz < 4 μm) where the adhesion is greater than 5 N / cm. This effectively solves the problems of insufficient adhesion and easy delamination between existing epoxy materials and low-polarity substrates (such as M8).

[0089] 3. It possesses both high heat and chemical resistance and the unique ability to support the fabrication of ultra-fine circuits:

[0090] The stable chemical structure of the film-forming resin (polymers containing aromatic heterocyclic backbones, such as PI / BMI) and the high cross-linking density network formed after curing of the bonding resin (epoxy / phenolic system) endow the material with excellent heat and pressure resistance (withstanding high temperature and pressure conditions greater than 180℃ and 1.8MPa) and chemical resistance. Surface-modified inorganic fillers also contribute to improving the overall thermal stability and chemical inertness of the material. Therefore, this material can withstand the attack of strong acid and alkali solutions (such as swelling, permanganate, sodium hydroxide, etc.) in the PTH process without significant loss. At the same time, due to the strong chemical bonding or interfacial interaction between the KDS material and metals such as copper, it can achieve extremely low surface roughness (Ra<0.1um / 0.2um, Rz<4um) after desmearing treatment, while still maintaining high adhesion to subsequent metal plating layers (>5N / cm). This characteristic of "high adhesion even with low roughness" directly breaks through the technical bottleneck of traditional processes, making it possible to manufacture ultra-fine lines with low loss L / S=2 / 2μm, significantly reducing skin effect loss in high-frequency signal transmission, and supporting laser patterning without causing charring problems.

[0091] 4. Flexible and diverse applications, strong process adaptability: The adjustability of the formulation of this invention allows for precise control of the material's rheological properties, curing behavior, and final form by adjusting the type of resin, molecular weight, filler content, and possible addition of flow-adjusting resins. Therefore, the composite dielectric sheet material of this invention can be manufactured into various product forms as needed, such as single-layer film (KDS), resin-clad copper foil (KDS-RCC), or combined with prepreg (KDS-GCP). Furthermore, it can also be formulated into a slurry form for processes such as overlay, via plugging, and planarization. Its excellent dielectric properties also allow it to be used as an embedded capacitor material. This flexibility enables this invention to adapt to various processing techniques such as coating, lamination, printing, and filling, meeting diverse needs from substrate manufacturing to packaging integration. Attached Figure Description

[0092] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0093] Figure 1This is a schematic flowchart of an embodiment of the method for preparing the composite dielectric sheet fabric of the present invention;

[0094] Figure 2 This is a schematic flowchart of an embodiment of a method for manufacturing a circuit board according to the present invention;

[0095] Figure 3 This is a schematic flowchart of an embodiment of another method for manufacturing a circuit board according to the present invention.

[0096] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0097] 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 a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0098] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0099] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution that simultaneously satisfies A and B. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0100] This invention proposes a composite dielectric sheet fabric.

[0101] In this embodiment of the invention, the composite dielectric sheet material includes a polymer resin and an inorganic filler. The polymer resin provides the composition with basic core functions such as film-forming properties, adhesion, and dielectric optimization, while the inorganic filler acts as a reinforcing phase, significantly improving the mechanical strength, heat resistance, and dimensional stability of the cured dielectric layer.

[0102] Specifically, polymeric resins include film-forming resins, adhesive resins, and dielectric-modified resins.

[0103] The film-forming resin mainly plays the role of the skeleton in the composition. Its core function is to provide heat resistance and film-forming basis for the dielectric layer that is finally cured, thereby achieving morphological stability and reducing the coefficient of thermal expansion in high-frequency processing.

[0104] Film-forming resins primarily play a role in imparting excellent toughness, heat resistance, and chemical resistance to materials within the composition. While the introduction of large amounts of inorganic fillers in high-filler systems can increase hardness and reduce thermal expansion, it can also easily lead to material brittleness. The introduction of film-forming resins can form a tough skeleton within the cured network, effectively absorbing and dispersing stress, thereby significantly improving the mechanical toughness and crack resistance of the entire composite dielectric sheet fabric. Simultaneously, its excellent chemical inertness is crucial in ensuring the material's resistance to corrosion from strong acids (such as sulfuric acid, hydrochloric acid, nitric acid, hydrogen peroxide, etc.) and strong alkalis (such as swelling agents, permanganate, sodium hydroxide, potassium hydroxide, and sodium ethylenediaminetetraacetate, etc.) in wet chemical processes such as deswearing and copper plating in the semi-additive process (SAP). Furthermore, film-forming resins can effectively reduce the overall dielectric constant (Dk) and dielectric loss factor (Df), and improve the Tg point and thermal stability.

[0105] In some embodiments of the present invention, the film-forming resin comprises a polymer with an aromatic heterocyclic backbone. The molecular backbone of such polymers contains a highly stable aromatic heterocyclic structure; it is this rigid and conjugated chemical structure that endows them with excellent high-temperature resistance, dimensional stability, and resistance to various chemical solvents and etching solutions.

[0106] Specifically, the polymer containing the aromatic heterocyclic backbone may be selected from at least one of polyimide, modified polyimide, and modified bismaleimide.

[0107] Specifically, the polyimide can be selected from liquid polyimide or thermoplastic polyimide (TPI). Liquid polyimide has good processability, while thermoplastic polyimide offers superior toughness.

[0108] The structural formula of liquid polyimide can be:

[0109] The structural formula of thermoplastic polyimide can be:

[0110] Specifically, modified bismaleimide can be a polyimide-modified bismaleimide, which combines the toughness of polyimide with the high heat resistance and high crosslinking density of bismaleimide, thereby further optimizing the overall performance of the material.

[0111] The structural formula of the modified bismaleimide can be:

[0112] The structural formula of PI-modified bismaleimide can be:

[0113] Among these, modified bismaleimide resin and polyimide contain more nonpolar and hydrophobic groups in their structure. In addition to improving toughness, heat resistance and solvent solubility, they are not easily polarized in an electric field and have the expected low dielectric properties.

[0114] As the core component in the system that forms a three-dimensional cross-linked network and ensures strong adhesion to the substrate, the bonding resin's main function is to form a dense, high-strength network structure through a curing reaction. This network not only tightly "glues" a large number of inorganic filler particles together to form a robust whole, but also enables the entire dielectric layer to form a strong chemical or physical bond with the surfaces of various substrates with different properties, such as copper foil, epoxy fiberglass cloth, M8 substrate, glass, or ceramics. Simultaneously, the bonding resin can also significantly improve the cross-linking density, hardness, heat resistance, and chemical resistance of the dielectric layer by forming effective chemical or physical bonds with the film-forming resin and the surface of inorganic fillers.

[0115] In some embodiments of the present invention, the bonding resin comprises an epoxy resin and a curing resin as a crosslinking agent thereon. The core function of this system is to form a dense, stable three-dimensional crosslinked network structure through a ring-opening addition reaction between the epoxy groups of the epoxy resin and the active groups (such as phenolic hydroxyl groups) of the curing resin. This structure significantly improves the cohesive strength, adhesion to substrates, heat resistance, and chemical resistance of the entire composition.

[0116] To achieve precise control over the final performance, the epoxy resin used in this invention can be one or a combination of various types of epoxy resins. Specifically, the epoxy resin is selected from at least one of glycidylamine epoxy resin, polyfunctional o-cresol aldehyde glycidyl ether type epoxy resin, phenol biphenyl epoxy resin, bisphenol F solid epoxy resin, isocyanate modified epoxy resin, naphthol type epoxy resin, and phenol phenolic epoxy resin. Specifically, the structural formula of glycidylamine epoxy resin is: Its epoxy equivalent is between 93 and 150 g / eq, its hydrolytic chlorine content is less than 200 ppm, and its viscosity at 25°C is between 0.5 and 5 Poise.

[0117] The structural formula of the multifunctional o-cresol formaldehyde glycidyl ether epoxy resin is: Its epoxy equivalent ranges from 195 to 230 g / eq, its hydrolytic chlorine at 120℃ ranges from 470 to 1000 g / eq, its ICI viscosity at 150℃ ranges from 0.9 to 60 Poise, and its softening point ranges from 45 to 96℃.

[0118] The structural formula of phenol-biphenyl epoxy resin is: Its epoxy equivalent ranges from 261 to 280 g / eq, hydrolytic chlorine content is less than 100 ppm, viscosity at 25°C is between 0.1 and 4.5 poise, and softening point is 45 to 75°C. Adding it to PVB and its hydroxyl groups in copolymerization can effectively improve the glass strength, Tg, and impact resistance of copper.

[0119] The structural formula of bisphenol F solid epoxy resin is: Its epoxy equivalent ranges from 450 to 1000 g / eq, hydrolytic chlorine content is less than 300 ppm, viscosity at 25°C is <1000 Poise, and softening point is 50–88°C. Solid bisphenol F epoxy resin is characterized by low viscosity and flexibility. The properties of its cured product are almost identical to those of bisphenol A epoxy resin. Adding it to PVB for copolymerization with its hydroxyl groups can effectively improve its corrosion resistance.

[0120] The structural formula of isocyanate (MDI) modified epoxy resin is:

[0121] Its epoxy equivalent ranges from 280 to 380 g / eq, hydrolytic chlorine content is less than 300 ppm, viscosity at 25°C is between 0.5 and 3 Poise, and softening point is 50 to 88°C. Solid bisphenol F epoxy resin is characterized by low viscosity and flexibility. The properties of its cured product are almost identical to those of bisphenol A epoxy resin. Adding it to PVB for copolymerization with its hydroxyl groups can effectively improve bond strength and peel strength.

[0122] The structural formula of naphthol-type epoxy resin is: Its epoxy equivalent ranges from 280 to 380 g / eq, its hydrolytic chlorine content is less than 300 ppm, its viscosity at 25°C is between 0.5 and 3 Poise, and its softening point is between 50 and 88°C. Its curing properties, heat resistance, and mechanical properties are superior to traditional bisphenol A. Furthermore, due to its lower internal stress, it exhibits higher Tg and better adhesive properties. When added to structural resins and copolymerized with their hydroxyl groups, it can effectively improve the Tg point, bond strength, and peel strength.

[0123] The structural formula of phenolic epoxy resin is: Its epoxy equivalent ranges from 165 to 200 g / eq, its hydrolytic chlorine content is less than 250 ppm, its viscosity at 25°C is between 1.1 and 12.5 Poise, and its softening point is 25 to 86°C. Because its molecular structure contains two or more epoxy groups, when added to structural resins and copolymerized with their hydroxyl groups, the resulting product has a high crosslinking density and excellent adhesive strength, heat resistance, and chemical resistance. The presence of two or more epoxy groups in its molecular structure leads to a high crosslinking density in the cured product, resulting in excellent adhesive strength, heat resistance, and chemical resistance.

[0124] In one specific embodiment, the curing resin is primarily a phenolic resin, the type and purity of which significantly influence the progress of the curing reaction and the properties of the final product. The phenolic resin can be selected from at least one of linear phenol-formaldehyde resin and linear BPA-formaldehyde resin. Selecting these phenolic resins, especially those with low free phenol content and low conductivity, is beneficial for ensuring the stability of the curing reaction and the electrical insulation properties of the final dielectric layer.

[0125] Specifically, the structural formula of linear phenol-formaldehyde resin is: Its free phenol content is <0.6%, softening point is 96-123℃, hydroxyl equivalent is between 105-119 g / eq, and electrical conductivity is less than 8 μS / cm.

[0126] The structural formula of linear BPA formaldehyde resin is: Its free phenol content is 1-45%, softening point is 90-140℃, hydroxyl equivalent is between 112-130 g / eq, and electrical conductivity is less than 20 μS / cm.

[0127] It is understood that by selectively combining and compounding the above-mentioned epoxy resins and phenolic resins, the present invention can flexibly adjust the various performance indicators of the waterborne plugging resin composition to meet the diverse protection needs of printed circuit boards of different specifications under specific processing techniques.

[0128] In some embodiments, the ratio of phenolic resin content to epoxy resin content satisfies the following formula:

[0129] Phenolic resin content = (hydroxyl equivalent of phenolic resin / epoxy equivalent of epoxy resin) × epoxy resin content.

[0130] The fundamental reason for using the above formula to determine the amount of the two resins is that it follows the stoichiometric principle in chemical reactions, aiming to achieve an ideal balance in the quantity of the two core functional groups participating in the reaction—the phenolic hydroxyl groups (-OH) on the phenolic resin molecular chain and the epoxy groups on the epoxy resin molecular chain—so as to obtain the curing product with the best performance.

[0131] Specifically, the curing process of the adhesive resin mainly involves a ring-opening addition reaction between phenolic hydroxyl groups and epoxy groups, forming a highly cross-linked three-dimensional network structure. Ideally, for this reaction to proceed most completely and efficiently, one phenolic hydroxyl functional group should react with exactly one epoxy functional group. Therefore, the ideal feed ratio should be such that the total molar ratio of phenolic hydroxyl groups to epoxy groups in the formulation is as close to 1:1 as possible.

[0132] Here, "Epoxy Equivalent Weight (EEW)" refers to the number of grams of epoxy resin containing 1 mole of epoxy groups, while "Hydroxyl Equivalent Weight (EEW)" refers to the number of grams of phenolic resin containing 1 mole of phenolic hydroxyl groups. These two values ​​are key parameters for measuring the reactivity of resins. Therefore, the essence of the above formula is a mathematical conversion of the chemical equilibrium relationship of "moles of phenolic hydroxyl groups ≈ moles of epoxy groups." By using this formula, the amount of phenolic resin containing an equal number of reaction sites can be accurately calculated based on the amount of epoxy resin used and its epoxy equivalent weight.

[0133] It is understandable that using this stoichiometric method to determine the proportions ensures the full progress of the crosslinking reaction and avoids the formation of a large number of unreacted functional groups in the cured network due to an excess of any one component. This results in the highest crosslinking density of the final cured adhesive resin, leading to superior heat resistance, chemical resistance, and the strongest mechanical strength and adhesion to the substrate.

[0134] In other embodiments, the curing resin may also contain at least one of benzoxazine, bismaleimide resin, reactive ester, and amine dicyandiamide curing agent, which may be used in conjunction with or as a substitute for phenolic resin to further adjust the reaction characteristics and final properties of the curing system.

[0135] Specifically

[0136] The structural formula of benzoxazine is:

[0137] The structural formula of the active ester is:

[0138] The structural formula of amine-based dicyandiamide curing agents is:

[0139] It is understood that by selectively combining and compounding the above-mentioned epoxy resins and phenolic resins, the present invention can flexibly adjust the various performance indicators of the composite dielectric sheet material to meet the diverse needs of high-frequency copper clad laminates of different specifications under specific processing technology.

[0140] It is worth noting that in some specific embodiments, in order to impart higher heat resistance or specific dielectric properties to the composite dielectric sheet fabric, the curing resin system may use benzoxazine resin and / or bismaleimide resin as the main curing agent component. In this case, traditional phenolic resin, reactive ester, or amine dicyandiamide curing agent may be added in small amounts or not at all, as needed.

[0141] Benzooxazine resins undergo ring-opening polymerization when heated, forming a highly cross-linked phenolic network structure, while their molecular structure itself exhibits low polarity. Bismaleimide resins, on the other hand, undergo addition polymerization or copolymerization via their terminal maleimide double bonds, forming a highly heat-resistant cross-linked network.

[0142] Therefore, when benzoxazine and / or bismaleimide resins are used as curing agents, they can form a network through their own polymerization reaction (self-curing) or undergo copolymerization with the epoxy resin in the bonding resin (co-curing), thereby constructing a final cured product with excellent heat resistance, low dielectric loss, and high dimensional stability. This choice of curing system provides a wider range of performance control for the composite dielectric sheet fabric of the present invention.

[0143] In some embodiments, to precisely control the flowability of the encapsulating material at low temperatures and its adhesion to the substrate, the adhesive resin may further comprise one or more flowability-adjusting resins. These flowability-adjusting resins may be selected from at least one of semi-crystalline epoxy resins, liquid bisphenol A type epoxy resins, liquid bisphenol F type epoxy resins, liquid bisphenol A-bisphenol F composite epoxy resins, liquid bisphenol S epoxy resins, liquid phenolic epoxy resins, and liquid phenolic resins. These flowability-adjusting resins typically have low epoxy equivalents (between 140 g / eq and 214 g / eq), low hydrolytic chlorine (less than 250 ppm), and low room temperature viscosity (between 1300 mPa·s and 4500 mPa·s at 25°C). Blending them as part of the adhesive resin can effectively improve the overall processability of the composition before coating or pressing, while ensuring high crosslinking density, excellent bond strength, heat resistance, and chemical resistance of the cured product.

[0144] Specifically, the structural formula of the semi-crystalline epoxy resin is as follows:

[0145] The structural formulas of liquid bisphenol A type epoxy resin and liquid bisphenol F type epoxy resin are as follows:

[0146]

[0147] The structural formula of liquid bisphenol A-bisphenol F composite epoxy resin is:

[0148] The structural formula of liquid phenolic epoxy resin is:

[0149] The structural formula of liquid phenolic resin is

[0150] In some embodiments, the flowability adjusting resin accounts for no more than 50% by weight of the binder resin.

[0151] The core purpose of limiting this content is to achieve the optimal technical balance between "processability" and "final curing performance." Specifically, flowability modifier resins, such as liquid epoxy or liquid phenolic resins, primarily function to reduce the viscosity of the entire adhesive resin system in its uncured state, improving its flowability and thus facilitating processes such as coating and lamination. However, the molecular weight or functionality of these resins is generally lower than that of the solid or high-functionality resins (such as phenol-biphenyl epoxy resins) that form the main body of the adhesive resin.

[0152] If the amount of flow-adjusting resin used is too high, for example, exceeding 50% of the total weight of the binder resin, it will excessively dilute the base resin that provides the core performance, resulting in a decrease in the overall density of the three-dimensional cross-linked network formed after curing. This may lead to a deterioration in the final dielectric layer properties, such as a decrease in glass transition temperature (Tg), a decrease in mechanical modulus, and a reduction in heat resistance and chemical resistance, thus failing to meet the requirements of high-performance applications.

[0153] Therefore, by limiting its content to below 50%, it is ensured that the main performance framework of the bonding resin is not damaged while obtaining sufficient process fluidity, thereby ensuring that the dielectric layer formed by final curing still has excellent mechanical strength, high heat resistance and long-term reliability.

[0154] It is understood that by precisely controlling the proportion of the resin used for flow adjustment within this optimized range, the present invention can significantly improve the processing adaptability of the material without sacrificing the core performance of the final product, thereby balancing high performance and manufacturability.

[0155] Dielectric-modified resins serve as low-loss optimization components. Their core function is to reduce the polarizability of the polymer resin system by introducing non-polar hydrocarbon chain structures, thereby lowering the overall dielectric constant (Dk) and dielectric loss factor (Df). Furthermore, they synergistically improve the Tg point and thermal stability in conjunction with film-forming and binding resins. This compensates for the excessive losses inherent in traditional polar resin systems during high-frequency signal transmission.

[0156] In some embodiments of the present invention, the dielectric modified resin comprises at least one of polyphenylene ether resin, bismaleimide resin, benzoxazine resin, and hydrocarbon resin. Herein, the hydrocarbon resin comprises a modified hydrocarbon resin; the bismaleimide resin comprises a modified bismaleimide, which includes a polyimide-modified bismaleimide; and the benzoxazine resin comprises a modified benzoxazine.

[0157] Among these, the molecular chains of hydrocarbon resins are mainly composed of carbon-hydrogen bonds and carbon-carbon bonds with very small electronegativity differences, and contain almost no strongly polar groups. Under a high-frequency alternating electric field, its molecules do not undergo violent dipole orientation polarization, resulting in extremely low energy loss. In addition, its non-polar properties also endow the material with excellent hydrophobicity, effectively preventing the intrusion of moisture (a strongly polar molecule), thus ensuring that the dielectric layer can maintain stable high-frequency performance even in humid environments.

[0158] Polyphenylene oxide (PPO / PPE) resin, due to its high molecular backbone rigidity, good symmetry, and low polarity, inherently possesses excellent properties such as low dielectric constant, low dielectric loss, high heat resistance, and low water absorption. In this invention, using it as part or all of the dielectric modification resin can effectively contribute to the low-loss target of the final composite dielectric sheet fabric. Furthermore, PPO can be copolymerized with phenolic epoxy systems and exhibits good compatibility with binder resins.

[0159] Bismaleimide (BMI) and benzoxazine (BOZ) resins, while contributing primarily to heat resistance through their highly cross-linked network structures after curing (as mentioned above when used as film-forming resins or curing agents), also exhibit relatively low polarity in their cured product molecular structures (e.g., the network formed by curing BMI or the phenolic network formed by ring-opening of BOZ). Especially after modification with specific low-polarity groups, they can also positively contribute to reducing the overall dielectric loss of the system. Introducing them as part of a dielectric-modifying resin component can further enhance the heat resistance and dimensional stability of the material while optimizing dielectric properties.

[0160] The term "modification" as used here refers to the introduction of specific functional groups (such as vinyl, epoxy, or other low-polarity groups) into the molecular structure of the aforementioned polyphenylene ether, bismaleimide, or benzoxazine resins. The main purpose is to improve their compatibility, reactivity, or processing performance with other resin components in the system (such as bonding resins or film-forming resins). At the same time, care should be taken to select modification methods that do not significantly impair their low dielectric properties.

[0161] These resins (modified hydrocarbon resin, polyphenylene ether, modified bismaleimide, modified benzoxazine) can be used alone as dielectric modifying resins; or they can be compounded in any proportion to form dielectric modifying resin components, with the aim of further optimizing the balance of dielectric, thermal or mechanical properties of the final product through the synergistic effect of different low polarity materials.

[0162] In one specific embodiment, the hydrocarbon resin is a multifunctional vinyl aromatic copolymer, and the molecular structure of this multifunctional vinyl aromatic copolymer can be modified by copolymerization of vinyl groups with aromatic rings. Specifically, the structure of the multifunctional vinyl aromatic copolymer can be one or a combination of Formulas 1 to 7:

[0163]

[0164] Inorganic fillers are mainly used as mechanical property enhancers in compositions, significantly improving the mechanical properties (such as hardness, modulus), heat resistance, and dimensional stability of the dielectric layer formed by the composition. In this application, in order to improve the interfacial compatibility between the inorganic filler and the polymer resin matrix, prevent its agglomeration at high contents, and ensure that the two can effectively bond to transfer stress, the surface of the inorganic filler has undergone specific functional group modification.

[0165] In some embodiments of the present invention, the surface of the inorganic filler is modified with one or more functional groups selected from the group consisting of aniline, alkyl, nitrogen-containing functional groups on the main chain or branches, double-bonded functional groups, and epoxy groups. These functional groups can react with or form strong interactions with active groups (such as heterocyclic nitrogen or epoxy groups) in the polymer resin, thereby tightly anchoring the inorganic filler in the resin matrix. This results in a dielectric layer with higher hardness, Young's modulus, and flexural modulus, effectively resisting impacts and thermal stresses during high-frequency processing.

[0166] In some embodiments, the inorganic filler is selected from at least one of silica, hollow silica, nano-silica derived from polyhedral oligomeric silsesquioxanes, boron nitride, perfluoroalkoxyalkane (PFA), and polytetrafluoroethylene (PTFE).

[0167] Incorporating these inorganic fillers into a high proportion of a polymer resin matrix serves as a reinforcing framework and functional core, significantly improving the overall performance of the cured dielectric layer. They not only substantially enhance the mechanical properties of the composite material (such as hardness and modulus) and reduce the coefficient of thermal expansion (CTE), but also significantly influence the material's dielectric properties (Dk / Df), thermal conductivity, and processing characteristics through their own physicochemical properties.

[0168] This invention provides a variety of inorganic filler options, allowing for optimization of the specific properties of the composite dielectric sheet material according to specific application requirements during practical operation:

[0169] Selecting fillers such as silica, hollow silica, or nano-silica derived from polyhedral oligomeric silsesquioxanes can effectively improve the mechanical strength and dielectric properties of materials. In particular, nano-sized silica fillers, due to their small particle size and large specific surface area, help to obtain smoother drilled surfaces.

[0170] Choosing high thermal conductivity fillers such as boron nitride can significantly improve the heat dissipation capability of the dielectric layer at high temperatures, meeting the high thermal conductivity requirements of high-power applications such as AI products.

[0171] Choosing fluoropolymer fillers such as perfluoroalkoxyalkane (PFA) or polytetrafluoroethylene (PTFE), which have extremely low dielectric constants and dielectric losses, can maximize the reduction of the dielectric constant (Dk) and dielectric loss (Df) of the final product. In particular, it can more effectively reduce the dielectric constant and improve the insulation properties of the material to meet the most stringent high-frequency signal transmission requirements.

[0172] It is worth noting that, regardless of the type or number of inorganic fillers selected, according to the present invention, their surfaces must undergo specific functional group modification (such as aniline, alkyl, nitrogen-containing functional groups, double-bond functional groups, or epoxy groups) to ensure that they form a strong interfacial bond with the polymer resin matrix, thereby fully exerting their reinforcing and functional regulation effects and avoiding performance degradation caused by interfacial separation.

[0173] It is understood that by using the aforementioned inorganic fillers individually or in combination, and by incorporating specific surface modification techniques, the present invention can flexibly adjust the mechanical, thermal, dielectric, and processing properties of the composite dielectric sheet fabric to precisely meet the diverse and high-performance requirements of different high-frequency circuit boards in specific application scenarios. In some embodiments, the relative content of each major component in the composition is defined to achieve the optimal balance of various performance indicators. Specifically, the composite dielectric sheet fabric may contain 15% to 70% (e.g., 15%, 20%, 30%, 40%, 50%, 60%, 70%, etc.) of polymeric resin by weight percentage, and 30% to 85% (e.g., 30%, 40%, 50%, 60%, 70%, 80%, 85%, etc.) of inorganic fillers.

[0174] Specifically, inorganic fillers are the core components that impart high mechanical strength, low coefficient of thermal expansion (CTE), and high thermal conductivity to the final dielectric layer. By controlling their content within a relatively high range of 50% to 85%, sufficient rigidity and dimensional stability can be ensured in the cured dielectric layer. This effectively copes with the thermomechanical stresses introduced by processes such as high-temperature pressing and meets the heat dissipation requirements of high-power products such as AI. If the content of inorganic fillers is below 30%, their contribution to reducing the coefficient of thermal expansion and improving mechanical properties will be insufficient, potentially failing to meet the stringent requirements of high-performance applications for dimensional stability and reliability.

[0175] The polymer resin acts as a continuous phase matrix, tightly binding the high-content inorganic filler particles together and ensuring the entire dielectric layer adheres firmly to the circuit board substrate. If the polymer resin content is less than 15%, it is insufficient to form a continuous and complete resin network to encapsulate and bond the large amount of inorganic filler, potentially leading to poor film formation, material brittleness, and insufficient adhesion. Conversely, if the polymer resin content is higher than 70%, the relative content of inorganic filler decreases, resulting in a softer overall dielectric layer with a higher coefficient of thermal expansion, failing to achieve ideal mechanical strength and dimensional stability.

[0176] Therefore, by controlling the weight percentages of polymer resin and inorganic filler to within the ranges of 15% to 70% and 30% to 85% respectively, the present invention achieves an optimal balance between excellent mechanical and thermal properties and good film-forming properties and adhesion, ensuring that the composition can form a uniform, highly adhesive dielectric layer and provide sufficient rigidity and dimensional stability after curing to cope with subsequent complex processes.

[0177] In some embodiments of the present invention, the polymer resin comprises 40% to 85% (e.g., 40%, 50%, 60%, 70%, 80%, 85%, etc.) of film-forming resin by weight, 5% to 60% (e.g., 5%, 10%, 20%, 30%, 40%, 50%, 60%, etc.) of binding resin, and 1% to 55% (e.g., 1%, 3%, 5%, 7%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, etc.) of dielectric-modified resin.

[0178] The proportions of the components within this polymer resin are designed to precisely balance the multiple core properties sought by the composite dielectric sheet fabric of this invention: namely, excellent mechanical toughness and chemical resistance, strong adhesion to the substrate, and ultra-low dielectric loss.

[0179] As mentioned earlier, the film-forming resin, as the main framework of the polymer system, is the functional component that provides the excellent toughness, heat resistance, and chemical resistance of the final dielectric layer. To ensure that the dielectric layer maintains its structural integrity without cracking or erosion during high-temperature pressing and subsequent wet chemical processing, the film-forming resin must play a dominant role in the entire polymer system. By controlling its content within a relatively high range of 40% to 85%, a tough, stable, high-performance polymer network can be guaranteed after curing. If the film-forming resin content is below 40%, the toughness and chemical resistance it provides will be insufficient, potentially leading to brittleness in high-filler applications or inability to withstand the chemical attack of processes such as PTH (Polymerization Therapy).

[0180] The bonding resin (epoxy and phenolic system) is key to providing strong adhesion to substrates such as copper foil and M8 substrates, and to forming a dense cross-linked network to bond inorganic fillers. If the content of the bonding resin is less than 5%, its cross-linking modification and bonding effect will be insignificant, resulting in poor adhesion of the dielectric layer and a loose internal structure. Conversely, if its content is higher than 60%, it will lead to excessively high cross-linking density, increasing the brittleness of the entire polymer system. Furthermore, its relatively high polarity may negatively impact the final dielectric properties.

[0181] Dielectric-modified resins (polyphenylene ether resin, bismaleimide resin, benzoxazine resin, and hydrocarbon resin) are the core functional components for achieving ultra-low dielectric properties. If their content is less than 1%, their contribution to reducing the overall dielectric constant and dielectric loss of the system will not be significant enough to achieve the ideal high-frequency performance target. Conversely, if their content is higher than 50%, excessive low-polarity components may affect the compatibility of the entire polymer system and may weaken the adhesion of the dielectric layer to the metal circuit.

[0182] Therefore, by precisely controlling the contents of film-forming resin, adhesive resin and dielectric-modifying resin within the above-mentioned optimized range, the material's mechanical toughness, chemical resistance and strong adhesion to the substrate are perfectly balanced while ensuring ultra-low dielectric loss, thus achieving the best overall performance.

[0183] In one embodiment, the composite dielectric sheet fabric provided herein has excellent high-frequency dielectric properties after curing, specifically, its dielectric loss (Df) at high frequencies (e.g., 10 GHz) is less than 0.0025.

[0184] In some embodiments, to further improve the processability of the composite dielectric sheet composition during preparation, storage, and coating, as well as the final film quality, the composition may also contain additives, which may be selected from at least one of leveling agents, dispersants, and defoamers. The addition of these additives aims to optimize the physicochemical behavior of the composition during preparation, storage, and coating processes. Specifically:

[0185] The main function of dispersants is to improve and stabilize the dispersion of high-content inorganic fillers in a resin matrix. Dispersants can wet and coat the surface of inorganic filler particles, effectively preventing particle aggregation and sedimentation through electrostatic repulsion or steric hindrance, thereby ensuring the uniformity and storage stability of the slurry.

[0186] The main function of leveling agents is to improve the surface appearance of the composition during the coating and film-forming process. They reduce the surface tension of the slurry, promote its flow and spreading on the substrate film, and eliminate surface defects such as orange peel and pinholes that may occur during application, resulting in a smoother and more even surface of the final composite dielectric sheet.

[0187] The main function of defoamers is to eliminate air bubbles introduced into the slurry during preparation and application due to high-speed mixing or shearing. If these air bubbles remain in the final film layer, they will form pinholes or voids, which not only affect the appearance but also severely weaken the density and mechanical strength of the dielectric layer, reducing its electrical performance and reliability.

[0188] In one specific embodiment, examples of additives that may be used include leveling agent BYK530, dispersant BYK2152, and defoamer BYK333. It is understood that by introducing these functionally specific additives, the present invention ensures the stability and reliability of its resin composition during preparation and application, thereby providing a strong guarantee for the final formation of a high-quality, high-performance composite dielectric sheet fabric.

[0189] In some embodiments, the composition used to prepare composite dielectric sheet fabric also contains a solvent in order to adjust the viscosity and rheological properties of the composition to suit different coating processes (such as blade coating, screen printing, etc.).

[0190] The solvent mainly acts as a carrier medium in the composition. Its core function is to dissolve the polymer resin (including film-forming resin, adhesive resin and dielectric modified resin) and uniformly disperse inorganic fillers and other additives to form a uniform, stable liquid or paste system with a suitable application viscosity.

[0191] In some embodiments of the present invention, the solvent may be selected from at least one or a mixture thereof, of water, N-methylpyrrolidone, ethanol, acetone, ethyl acetate, n-butyl ether, methyl tert-butyl ether, dimethyl phthalate, butanone, dimethyl sulfoxide, n-butyl ketone, cyclohexanone, toluene, and xylene.

[0192] This invention provides a diverse selection of solvents to flexibly construct optimal solvent systems based on the solubility parameters of the specific polymer resins used. For example, high-boiling-point, highly polar solvents such as N-methylpyrrolidone and cyclohexanone are excellent for dissolving high-performance polymers such as polyimides; while medium- and low-boiling-point solvents such as butanone and toluene facilitate rapid evaporation during baking, improving production efficiency. By using these solvents individually or in combination, the viscosity, surface tension, drying rate, and storage stability of the final composition can be precisely controlled, ensuring its perfect adaptation to different industrial production processes.

[0193] The present invention also provides a method for preparing a composite dielectric sheet fabric, which is used to prepare the composite dielectric sheet fabric as described in any of the preceding claims.

[0194] like Figure 1 As shown, in some embodiments, the preparation method includes the following steps:

[0195] S1. Preparation of resin slurry: The film-forming resin, the binding resin and the dielectric modified resin are mixed in the first solvent to obtain the resin slurry.

[0196] This step aims to obtain a uniform, gel-free resin slurry as the basis for subsequent filler dispersion.

[0197] Specifically, the film-forming resin, the binder resin, and the dielectric-modified resin are mixed together in a first solvent. The film-forming resin provides a heat-resistant framework, the binder resin ensures cross-linking adhesion, and the dielectric-modified resin regulates low-loss characteristics.

[0198] In a preferred embodiment, to improve the mixing effect in subsequent steps, additives such as dispersants, leveling agents, and defoamers can be pre-dissolved or dispersed in the first solvent before adding the polymer resin component. Examples of additives that can be used include, but are not limited to, products such as BYK530, BYK 2152, and BYK333.

[0199] Specifically, the mixing process for preparing resin slurry can be achieved using high-speed mixing equipment such as an emulsifier. Of course, the emulsifier can be replaced by a high-speed mixer or a collider.

[0200] Furthermore, the mixing speed can be from 3600 rpm to 7200 rpm. To prevent the resin stability from being affected by the heat generated by high-speed shearing, the entire process can be carried out in a reactor with a cooling water jacket to ensure that the slurry temperature does not exceed 45°C. The mixing time can be any value between 60 minutes and 120 minutes, for example, 90 minutes, to ensure the formation of a homogeneous and stable resin slurry (also referred to as slurry A).

[0201] S2. Preparation of filler slurry: Inorganic fillers are mixed in a second solvent to obtain filler slurry.

[0202] This step aims to obtain a non-agglomerated filler slurry, ensuring uniform dispersion of inorganic fillers and avoiding uneven subsequent compounding.

[0203] Specifically, surface-modified inorganic fillers are mixed in a second solvent. The inorganic fillers provide mechanical reinforcement, while the surface-modified functional groups (such as aniline or epoxy groups) improve interfacial compatibility.

[0204] In a preferred embodiment, the dispersant and other additives can be pre-dissolved or dispersed in the second solvent before adding the inorganic filler to improve the dispersion efficiency of the filler. This process can employ similar equipment and process parameters as step S1, for example, using an emulsifier at a speed of 3600 rpm to 7200 rpm and a temperature not exceeding 45°C. The mixing time can be any value between 60 minutes and 120 minutes, such as 90 minutes, to ensure that the inorganic filler particles are fully wetted and uniformly dispersed, forming a non-agglomerated filler slurry (also referred to as slurry B).

[0205] It is worth noting that the first solvent and the second solvent can be the same or different. Specifically, the first solvent and the second solvent can be selected from at least one of N-methylpyrrolidone, ethanol, acetone, ethyl acetate, n-butyl ether, methyl tert-butyl ether, dimethyl phthalate, butanone, dimethyl sulfoxide, n-butyl ketone, cyclohexanone, toluene, and xylene.

[0206] S3. Mixing: The filler slurry is added to the resin slurry being stirred and mixed to obtain a composite dielectric sheet material mixed slurry in slurry form.

[0207] This step aims to achieve a uniform organic-inorganic composite to form the final slurry.

[0208] Specifically, the prepared filler slurry (slurry B) is slowly added to the resin slurry (slurry A) under stirring to prevent filler agglomeration due to excessively high local concentrations. After the addition is complete, thorough mixing is continued using equipment such as an emulsifier to ensure that the filler particles achieve optimal dispersion in the final resin composition. The process parameters for this final mixing step can be a rotation speed of 3600 rpm to 7200 rpm, a temperature not exceeding 45°C, and a duration of any value between 60 minutes and 120 minutes, such as 90 minutes, to obtain the final slurry-formed composite dielectric sheet fabric.

[0209] In some embodiments, in order to precisely control the workability (especially solid content and viscosity) of the final composition to suit different application requirements, the preparation method may further include a post-processing step S4 after step S3:

[0210] S4. Solvent Removal: The composite dielectric sheet fabric mixture is subjected to solvent removal treatment to obtain a composite dielectric sheet fabric ink with a solid content between 64% and 98% and a viscosity between 10000 Pa·s and 50000 mPa·s.

[0211] Specifically, this step can be achieved using specialized equipment, such as a vacuum mixer or a vacuum-heated mixer. The composite dielectric sheet material in slurry form obtained in step S3 is placed in the equipment, and while continuously stirring, the system is evacuated to a gauge pressure below 0.1 MPa. The vacuum environment significantly lowers the boiling point of the solvent, allowing it to evaporate efficiently at lower temperatures, thus avoiding premature reaction or degradation of the resin components that might occur during high-temperature processing.

[0212] Solid content is a core indicator for evaluating the workability of resin compositions. Controlling it within the range of 64% to 98% ensures the slurry has sufficient fluidity for coating (such as screen printing or blade coating) while also possessing high viscosity to form a dense dielectric layer. If the solid content is below 64%, it means the solvent content in the composition is too high, resulting in excessively low viscosity. This can cause high-density inorganic fillers to settle during storage or settling, disrupting the system's homogeneity. Furthermore, during subsequent coating and film formation, the evaporation of a large amount of solvent can lead to significant volume shrinkage, increasing the risk of film defects (such as pinholes and cracks), and significantly prolonging baking and curing time, thus reducing production efficiency. Conversely, if the solid content is above 98%, the solvent content in the composition is too low, resulting in excessively high viscosity and extremely poor fluidity. This makes it difficult to achieve uniform coating through blade coating, screen printing, or other methods, and may even fail to effectively wet the substrate film, thus affecting the final quality of the composite dielectric film.

[0213] Setting the ink viscosity range to 10,000 Pa·s to 50,000 mPa·s is primarily to ensure that the final composite dielectric sheet fabric ink has good processing applicability to meet the requirements of subsequent coating and molding processes. Specifically, the composite dielectric sheet fabric of this invention contains a high proportion (50%-85%) of inorganic fillers. If the ink viscosity is below 10,000 mPa·s, these high-density filler particles are prone to sedimentation during storage or settling, disrupting the ink's uniformity and leading to inconsistent final film performance. If the ink viscosity is above 50,000 mPa·s, its flowability becomes very poor, making it difficult to pass through the mesh of the screen / steel mesh or spread evenly under a doctor blade, resulting in uneven coating thickness, scratches, or voids.

[0214] To further improve the solvent removal efficiency, the composition can be gently heated, for example, by controlling the temperature within the range of 20°C to 50°C. By monitoring the viscosity of the composition or measuring its solid content by sampling, the vacuum stirring process is continued for 5 minutes to 3 hours until the performance indicators of the composition reach the preset values, thereby obtaining an ink-like composition suitable for subsequent coating and molding.

[0215] The reason for setting the above temperature parameters is that controlling the temperature within a mild heating range of room temperature (20°C) to 50°C provides sufficient energy for solvent molecules to accelerate their evaporation rate in a vacuum environment, thereby effectively improving solvent removal efficiency. If the temperature is too low (e.g., below room temperature), the solvent evaporation rate will be too slow, resulting in an excessively long process time and making industrial production impractical. However, if the temperature is above 50°C, there is a risk of premature cross-linking of thermally reactive components such as the binding resin (epoxy and phenolic system). Once premature cross-linking occurs, the viscosity of the composition will irreversibly increase sharply, and even gelation may occur, thereby shortening its shelf life and pot life, ultimately leading to the scrapping of the entire batch of material. Therefore, the present invention selects a mild heating condition not exceeding 50°C, which is key to ensuring effective solvent removal while maintaining the chemical stability of the resin composition.

[0216] The reason for setting the above time parameters is that this time range (5 minutes to 3 hours) provides the necessary flexibility and effectiveness for process operation under different production scales and initial solvent contents. The time required for solvent removal is closely related to factors such as the batch size of the material to be treated, the initial solid content, and equipment efficiency. For small batches of materials or materials with low initial solvent content, the target solid content can be reached in a short time of about 5 minutes. However, for large batches of materials or materials that require the removal of more solvent, a processing time of up to 3 hours may be required. If the processing time is less than 5 minutes, it may not be sufficient to raise the solid content to the target range, resulting in a low viscosity of the composition. Conversely, if the processing time exceeds 3 hours, it will not only reduce production efficiency and increase energy consumption, but may also cause slow side reactions of sensitive components in the system due to sufficient heat accumulation from prolonged gentle heating, thereby affecting the long-term storage stability of the composition. Therefore, 5 minutes to 3 hours is an optimized and reasonable process time window that can balance production efficiency, process flexibility, and product stability.

[0217] In some embodiments, the preparation method may further include a molding step S5:

[0218] S5. Dry Film Preparation: The composite dielectric sheet fabric ink is coated onto the substrate film and cured to obtain a composite dielectric sheet fabric dry film. This step aims to transform the resin composition in ink form prepared in the previous steps into a solid dry film with a specific thickness, uniformity, and suitable for subsequent processing. This step may specifically include two stages: coating and solvent removal.

[0219] Coating: The ink-like composition with a specific solid content and viscosity obtained in the preceding steps is uniformly applied to the surface of a substrate film using a suitable coating method. The substrate film can be polyethylene terephthalate (PET), polyimide (PI), or other flexible film materials, and its function is to provide temporary mechanical support and protection for the composite dielectric sheet fabric. Application methods can include blade coating, screen / stencil printing, pad printing, and dispensing, etc. The specific method can be adjusted according to the required thickness accuracy and production efficiency of the final product.

[0220] Solvent removal treatment: The substrate film coated with the composition is placed in a heating device such as a hot air furnace for baking to remove the residual solvent in the composition and to allow it to initially solidify into a solid film with a certain mechanical strength, i.e., a composite dielectric sheet material in the form of a dry film.

[0221] In a preferred embodiment, the solvent removal process can be carried out at a temperature of 50°C to 120°C for 30 seconds to 30 minutes. The reason for setting the temperature and time parameters for the solvent removal process is as follows:

[0222] Setting the lower limit of temperature to 50°C ensures that solvent molecules have sufficient energy to escape efficiently from the coating. If the temperature is below 50°C, the solvent evaporation rate will be too slow, which will not only greatly prolong the production time, but may also cause solvent residue to remain inside the film, resulting in a soft final dry film with insufficient mechanical strength.

[0223] Controlling the temperature limit to 120℃ ensures effective solvent evaporation while preventing premature cross-linking of thermally reactive components such as the bonding resin (epoxy / phenolic system). This guarantees that the resulting dry film retains good flowability and adhesion when subsequently hot-pressed onto the circuit board substrate. Excessive temperature may lead to over-curing of the dry film, affecting its bonding performance in the final application.

[0224] Setting the minimum baking time to 30 seconds ensures sufficient time for the solvent inside the film to evaporate completely. Too short a baking time will result in incomplete curing, affecting the physical properties and operability of the dry film.

[0225] Setting the time limit at 30 minutes ensures complete solvent removal while maintaining efficiency for industrial production. Exceeding this time offers little improvement to dry film performance but significantly reduces production line output efficiency and increases energy consumption.

[0226] By precisely controlling the parameters in the coating and molding process, the preparation method of the present invention can stably produce high-quality composite dielectric sheet dry films with uniform thickness and consistent performance, providing a reliable material basis for subsequent applications in circuit board manufacturing.

[0227] The present invention also proposes a method for manufacturing a circuit board, which uses the composite dielectric sheet material described in any of the foregoing embodiments as a high-performance add-layer or filler material to construct a dielectric structure with excellent electrical performance and high reliability during the manufacturing process of high-frequency and high-speed circuit boards.

[0228] Reference Figure 2 In one embodiment, the preparation method may include the following steps:

[0229] S10. Provide substrate: Provide a circuit board substrate with the area to be added.

[0230] First, a circuit board substrate to be processed is provided. Depending on the application requirements, this substrate can be a conventional epoxy fiberglass cloth substrate (such as FR4 prepreg or fully cured sheet), a high-performance M8 to M10 substrate, a Teflon (PTFE) substrate, or a special glass substrate or ceramic substrate. The target area can be a planar area where additional layers are needed to build a more complex circuit structure.

[0231] S20. Apply composite dielectric sheet material: Apply the composite dielectric sheet material described in any of the preceding items to the area of ​​the circuit board substrate to be added to form an added layer structure.

[0232] Specifically, the appropriate application method is adopted according to the different product forms of the composite dielectric sheet fabric (such as ink, dry film, etc.).

[0233] In one embodiment, when using composite dielectric sheet fabric ink as the starting material, the step of applying the composite dielectric sheet fabric may further include the following sub-steps:

[0234] S21. Preparation of dry film: The composite dielectric sheet fabric composition in ink form obtained by the aforementioned preparation method is uniformly coated onto the surface of a carrier by methods such as doctor blade coating, screen printing, or stencil printing. The carrier can be a flexible substrate film (e.g., PET film) or a copper foil layer. Subsequently, the ink-coated carrier is placed in a hot air oven and dried at a temperature range of 50°C to 120°C for 30 seconds to 30 minutes to remove most of the solvent from the ink, thereby obtaining a composite dielectric sheet fabric in solid dry film form attached to the carrier.

[0235] It is worth noting that, in specific embodiments of the present invention, the proposed composite dielectric sheet fabric can be prepared into different product forms according to the needs of downstream applications. One important product form is called KDS-RCC.

[0236] KDS-RCC is a composite material product of this invention, and its name consists of two parts:

[0237] KDS: refers to the composite dielectric sheet material of the present invention, namely the high-performance dielectric material that includes a specific resin system (film-forming resin, bonding resin, dielectric modified resin) and surface-modified inorganic filler.

[0238] RCC is an abbreviation for "Resin Coated Copper".

[0239] Therefore, "KDS-RCC product" specifically refers to a resin-coated copper foil product formed by pre-coating the KDS high-performance dielectric resin material of the present invention onto the rough surface of copper foil.

[0240] A typical KDS-RCC product structure (during the "KDS-RCC preparation" phase) usually consists of the following three layers:

[0241] Copper Foil: Serves as both substrate and carrier. KDS resin is coated onto its roughened surface to utilize the roughness of the copper foil to impart specific microstructures to the KDS layer surface in subsequent processes.

[0242] KDS Resin Layer: This is the composite dielectric sheet material of the present invention, which is attached to the rough surface of the copper foil by coating and drying.

[0243] Protective Film: Covers the surface of the KDS resin layer to protect the KDS layer from contamination or damage during storage, transportation, and pre-lamination operations.

[0244] Therefore, in step S21, when the carrier is a copper foil layer, the corresponding product form is KDS-RCC.

[0245] S22. Lamination: The prepared composite dielectric sheet fabric dry film with carrier is laminated onto the target area of ​​the circuit board substrate by hot pressing. Specifically, hot pressing can be applied within a temperature range of 50°C to 150°C and maintained for 30 seconds to 30 minutes to soften the dry film and allow it to adhere tightly to the substrate. This temperature range is designed to soften the polymer resin system in the composite dielectric sheet fabric to a certain degree of fluidity, thereby fully wetting the substrate surface and filling the surface microstructure, ensuring a tight, gapless physical contact between the two, laying the foundation for subsequent strong adhesion. At the same time, this temperature is lower than the rapid curing temperature of the resin system, avoiding loss of fluidity due to premature cross-linking and ensuring excellent bonding performance.

[0246] S23. Curing: After bonding, the entire assembly is placed in an oven or press for final curing at a temperature range of 120°C to 250°C for 10 minutes to 5 hours. Through this high-temperature curing process, the resin components in the composite dielectric sheet undergo a full cross-linking reaction, ultimately forming a robust, bonded laminate structure with the desired properties on the circuit board substrate. This temperature range is set to provide sufficient activation energy for the chemical cross-linking reaction of thermosetting components such as the bonding resin (epoxy and phenolic systems). Sufficient baking at this high temperature drives the resin molecular chains to react, forming a highly cross-linked, dense, and stable three-dimensional network structure. This process optimizes the material's mechanical strength, heat resistance (Tg), chemical resistance, and adhesion to the substrate, resulting in a robust and reliable laminate structure.

[0247] In another embodiment, when a pre-prepared composite dielectric sheet dry film is used directly as the starting material (the dry film itself may be attached to a carrier, such as a substrate film or copper foil), the step of applying the composite dielectric sheet mainly includes the following sub-steps:

[0248] S24. Lamination: Align the composite dielectric sheet dry film (along with its carrier, if present) directly with the target area of ​​the circuit board substrate, and then perform hot pressing within a temperature range of 50°C to 150°C for 30 seconds to 30 minutes to achieve tight bonding between the dry film and the substrate.

[0249] S25. Curing: After bonding, a final curing process is performed within a temperature range of 120°C to 250°C for 10 minutes to 5 hours to ensure complete cross-linking and curing of the composite dielectric sheet, forming the required additive structure on the circuit board substrate. The temperature and time parameters for steps S24 and S25 can be referenced in steps S22 and S23 above, and will not be repeated here.

[0250] It is worth noting that, in the specific embodiments of the present invention, in addition to KDS-RCC, the proposed composite dielectric sheet material can also be prepared into another important product form, which is called KDS-GCP.

[0251] KDS-GCP is also a composite material product of this invention, and its name consists of two parts:

[0252] KDS: refers to the composite dielectric sheet material of the present invention, namely the high-performance dielectric material that includes a specific resin system (film-forming resin, bonding resin, dielectric modified resin) and surface-modified inorganic filler.

[0253] GCP: Usually refers to "Glass Cloth Prepreg". In the context of this document, GCP more broadly refers to the substrate material bonded to the KDS layer, especially substrates in prepreg form, such as FR4 or M8 prepregs.

[0254] Therefore, "KDS-GCP product" specifically refers to a composite structure product formed by pre-combining the KDS high-performance dielectric resin material of the present invention with a substrate material (usually a prepreg, such as FR4 or M8 Prepreg).

[0255] A typical structure of a KDS-GCP product (during the "KDS-GCP preparation" phase) usually consists of the following three layers:

[0256] Substrate Layer: This is usually a glass fiber cloth prepreg (such as FR4 PP or M8PP), but it can also be other types of substrate materials.

[0257] KDS resin layer: This is the composite dielectric sheet material of the present invention, which is attached to the substrate layer.

[0258] PET release film: Covers the surface of the KDS resin layer to protect the KDS layer and is removed before subsequent use.

[0259] Therefore, the product obtained in steps S23 (where the substrate film is the carrier of the composite dielectric sheet dry film) and S25 is KDS-GCP.

[0260] Following the two embodiments described above, and before subsequent surface treatment steps, a carrier removal step is typically required. The purpose of this step is to remove the carrier layer that provides temporary support during dry film preparation or lamination, exposing the surface of the laminated structure formed after the composite dielectric sheet fabric has cured, thus preparing for subsequent surface treatment and metallization. The specific removal method depends on the carrier material:

[0261] When the carrier is a substrate film (such as PET film), it can usually be peeled off from the surface of the cured laminate structure by mechanical tearing.

[0262] When the carrier is a copper foil layer, the copper foil layer needs to be removed by chemical etching.

[0263] It is understood that by selecting different process paths and key carrier removal steps, the present invention can flexibly and effectively apply and solidify high-performance composite dielectric sheet material onto the circuit board substrate, laying the foundation for subsequent high-precision surface treatment and metal circuit fabrication.

[0264] S30. Surface treatment: The added-layer structure is surface treated to make the surface roughness Ra of the added-layer structure not greater than 0.2 μm and Rz not greater than 4 μm.

[0265] In one specific embodiment, this surface treatment can be achieved through standard chemical treatment steps in a semi-additive process (SAP), for example, treating the dielectric layer surface with a fluffy, high-manganese, neutralizing solution used in a PTH process. The composite dielectric sheet fabric of this invention, due to its excellent chemical resistance, can withstand treatment with these strong chemicals without structural damage, while simultaneously forming a controllable, extremely low-roughness surface. This characteristic is crucial for high-frequency signal transmission because it significantly reduces skin effect losses caused by conductor surface roughness, thereby ensuring signal integrity.

[0266] S50, Metallization treatment: Metal circuits are fabricated on the surface of the layered structure using a semi-additive method, wherein the pull-out force between the formed metal circuits and the layered structure is not less than 5 N / cm, and ultra-fine circuits can be fabricated.

[0267] The reason why the composite dielectric sheet material (KDS material) of the present invention can support the manufacture of fine lines, especially ultra-fine lines with a line width / spacing (L / S) of 2 / 2μm, is that it has successfully overcome the technical contradiction between the surface roughness of the dielectric layer and the adhesion of the metal line in the traditional semi-additive process (SAP / MSAP).

[0268] Specifically, in traditional processes, to ensure that the subsequent electroless copper plating layer adheres firmly to the dielectric layer surface, a desmearing process is typically performed on the dielectric layer surface to artificially create deeper micro-pits (i.e., higher surface roughness) to provide sufficient mechanical anchoring points. However, this high surface roughness is extremely detrimental to high-frequency signal transmission. At high frequencies, current tends to flow along the surface of the conductor (i.e., the skin effect). A rough conductor surface increases the actual current transmission path length and induces scattering, resulting in significant signal attenuation and loss, severely limiting the signal transmission rate and quality. Therefore, a core requirement for manufacturing high-frequency, high-speed, and fine-grained circuits is to minimize the surface roughness of the dielectric layer and conductor lines.

[0269] One of the most prominent advantages of the composite dielectric sheet material of this invention is that it achieves extremely low surface roughness while maintaining extremely high adhesion to subsequently formed metal circuits (such as electroless copper plating). Specifically, due to the excellent chemical stability and unique surface properties of the KDS material itself, even after standard PTH descaling process, its surface can still maintain extremely low controllable roughness (e.g., Ra no greater than 0.2 μm, or even Ra < 0.1 μm; Rz no greater than 4 μm).

[0270] More importantly, even with such extremely low surface roughness, the KDS material of this invention, thanks to the strong chemical bond or interfacial interaction formed between it and the metal (especially copper), can still ensure that the metal circuits subsequently formed by the semi-addition method have extremely high peel strength (or pull-out force), which can stably reach more than 5 N / cm.

[0271] It is this unique combination of "high adhesion despite low roughness" that makes the KDS material of this invention an ideal substrate for manufacturing ultra-fine circuits. Low roughness ensures low-loss transmission of high-frequency signals, while high adhesion ensures that even when the line width / spacing is reduced to the 2 / 2 μm level, these extremely fine metal lines can still adhere firmly to the dielectric layer without peeling or breaking during subsequent manufacturing processes or actual use, thus guaranteeing circuit reliability.

[0272] Therefore, by providing a composite dielectric sheet material that can simultaneously meet the seemingly contradictory requirements of low surface roughness and high metal adhesion, this invention successfully solves the key bottleneck in the prior art, providing a reliable material basis for manufacturing ultra-fine lines with line width / spacing (L / S) reaching the level of 2 / 2μm, and perfectly meeting the stringent requirements of high-density, high-frequency and high-speed wiring for high-performance chip substrates such as AI and GPU.

[0273] This invention also proposes another method for fabricating circuit boards, which is particularly suitable for applications requiring the formation of hole structures (such as through-holes or blind vias) after the application of a dielectric layer. This method also utilizes the composite dielectric sheet material described in any of the foregoing embodiments as the core dielectric material.

[0274] like Figure 3 As shown, in a specific embodiment, the preparation method may include the following steps:

[0275] S110, Provide substrate: Provide a circuit board substrate with areas to be drilled.

[0276] First, a circuit board substrate to be processed is provided. The type of substrate can be selected according to the requirements of the final product, such as an epoxy fiberglass cloth substrate, an M8 to M10 substrate, etc. The substrate has areas to be drilled where hole structures need to be formed.

[0277] S120. Apply composite dielectric sheet material: Apply the composite dielectric sheet material described in any of the preceding items to the area to be drilled on the circuit board substrate to form a dielectric layer.

[0278] This step aims to form a uniform, high-performance dielectric layer on the substrate surface before subsequent drilling operations. The specific application method varies depending on the initial form (ink or dry film) of the composite dielectric sheet used.

[0279] When using composite dielectric sheet fabric ink, this step may further include:

[0280] Preparation of dry film: The composite dielectric sheet fabric ink is coated onto a carrier (e.g., a substrate film or copper foil layer) and dried in a temperature range of 50°C to 120°C for 30 seconds to 30 minutes to obtain a composite dielectric sheet fabric dry film attached to the carrier.

[0281] Bonding: The dry film with the carrier is hot-pressed onto the circuit board substrate at a temperature range of 50°C to 150°C and maintained for 30 seconds to 30 minutes.

[0282] Curing: The laminated dry film is cured at a temperature range of 120°C to 250°C for 10 minutes to 5 hours to form a dielectric layer that is firmly bonded to the substrate.

[0283] When using a composite dielectric sheet fabric dry film, this step may further include:

[0284] Bonding: The composite dielectric sheet dry film (usually with a carrier) is hot-pressed onto the circuit board substrate at a temperature range of 50°C to 150°C and maintained for 30 seconds to 30 minutes.

[0285] Curing: The laminated dry film is cured at a temperature range of 120°C to 250°C for 10 minutes to 5 hours to form a dielectric layer that is firmly bonded to the substrate.

[0286] Furthermore, if a carrier is attached to the dry film, it must be removed before proceeding with the next drilling step. The specific removal method depends on the carrier material: when the carrier is a substrate film, it is removed mechanically; when the carrier is a copper foil layer, it is removed chemically.

[0287] S130. Drilling: A hole structure is formed on the circuit board substrate and the dielectric layer by means of laser drilling or mechanical drilling.

[0288] On the established dielectric layer, according to design requirements, a laser or mechanical drill bit is used to perform drilling operations in the designated drilling area to form a hole structure (such as a through hole or blind hole) that penetrates the dielectric layer and the underlying substrate (partially or entirely).

[0289] S140, De-adhesive removal: De-adhesive removal is performed on the hole structure to modify the edges of the hole structure and remove drilling residue.

[0290] The drilling process may produce resin residue or burrs on the hole walls or edges. The desmearing step aims to remove these residues through chemical treatment (e.g., using a solution containing a bulking agent and permanganate) and micro-etch the hole walls to create a clean, appropriately rough surface, providing a good foundation for subsequent metallization. The composite dielectric sheet fabric of this invention, due to its excellent chemical resistance, can withstand the strong chemical treatment in this step without being excessively eroded.

[0291] S150, Metallization: Metallize the surface of the hole structure and the dielectric layer after the adhesive removal process to form metal lines on the hole wall of the hole structure and the surface of the dielectric layer.

[0292] This step aims to achieve electrical interconnection within the holes and to form conductive patterns on the surface of the dielectric layer. In a preferred embodiment, the metallization process may include:

[0293] Electroless copper plating: First, a thin and uniform conductive seed layer (usually copper) is deposited on the hole walls and dielectric layer surface after the resist removal process by electroless plating.

[0294] Copper plating: Then, based on this seed layer, copper is selectively thickened in the areas where the circuit needs to be formed (including the hole walls) by electroplating (usually in conjunction with patterned photoresist), ultimately forming a metal circuit with the designed thickness and pattern.

[0295] Thanks to the superior properties of the composite dielectric sheet material of this invention, this preparation method can obtain high-quality circuit boards. Specifically, after the adhesive removal step, the surface roughness of the dielectric layer can be controlled at an extremely low level, with Ra not exceeding 0.2 μm and Rz not exceeding 4 μm. Furthermore, the metal lines formed in the metallization step have a strong bond with the dielectric layer, and its peel strength is not less than 5 N / cm. This combination of low roughness and high adhesion makes this method particularly suitable for manufacturing advanced circuit boards requiring precise hole structures and high-frequency, high-speed performance.

[0296] In summary, the composite dielectric sheet fabric proposed in this application has the following beneficial effects:

[0297] 1. Achieves superior high-frequency, low-loss dielectric properties and enhances substrate grade:

[0298] Dielectrically modified resins (such as hydrocarbon resins) have extremely low molecular polarity, fundamentally reducing polarization loss in high-frequency electric fields. Simultaneously, surface-modified inorganic fillers, particularly those with inherently low dielectric loss (such as PTFE), form a low-polarity synergistic composite system with the resin matrix. This low-loss characteristic directly reduces energy attenuation during high-frequency signal transmission, crucial for ensuring signal integrity. Therefore, by introducing dielectrically modified resins and inorganic fillers, the composite dielectric sheet fabric of this invention exhibits extremely low dielectric constant (Dk between 3.0 and 3.3, or even below 3.0) and dielectric loss (Df between 0.0015 and 0.0025, or even below 0.0015) at high frequencies (e.g., 10 GHz) after curing. Thus, when the composite dielectric sheet fabric is applied to traditional substrates (such as epoxy fiberglass cloth substrates, M8-M10 substrates, glass and ceramic substrates), it can significantly improve and enhance the surface dielectric properties of the traditional substrates. Its superior performance can even elevate the overall characteristics of ordinary epoxy fiberglass cloth substrates (FR4) with poor dielectric loss to the level of expensive M8 materials.

[0299] 2. Possesses excellent cross-material adhesion and interfacial compatibility:

[0300] The bonding resins (including phenolic resins and epoxy resins) can form strong chemical bonds or physical adsorption with the surfaces of different substrates. Simultaneously, the robust framework provided by the film-forming resin (such as PI / BMI) enhances interfacial stability. More importantly, the specific functional group modification of the inorganic filler surface (such as aniline, alkyl, nitrogen-containing functional groups, epoxy groups, etc.) acts as a bridge, enabling strong interactions with both the polymer resin matrix and the substrate surface. Therefore, through the synergistic effect of the bonding resins, film-forming resins, and surface-modified inorganic fillers, the composite dielectric sheet fabric of this invention exhibits excellent adhesion to various substrates, particularly with ceramic and glass substrates where the adhesion is greater than 10 N / cm, and with copper even at low surface roughness (Ra < 0.2 μm, Rz < 4 μm) where the adhesion is greater than 5 N / cm. This effectively solves the problems of insufficient adhesion and easy delamination between existing epoxy materials and low-polarity substrates (such as M8).

[0301] 3. It possesses both high heat and chemical resistance and the unique ability to support the fabrication of ultra-fine circuits:

[0302] The stable chemical structure of the film-forming resin (polymers containing aromatic heterocyclic backbones, such as PI / BMI) and the high cross-linking density network formed after curing of the bonding resin (epoxy / phenolic system) endow the material with excellent heat and pressure resistance (withstanding high temperature and pressure conditions greater than 180℃ and 1.8MPa) and chemical resistance. Surface-modified inorganic fillers also contribute to improving the overall thermal stability and chemical inertness of the material. Therefore, this material can withstand the attack of strong acid and alkali solutions (such as swelling, permanganate, sodium hydroxide, etc.) in the PTH process without significant loss. At the same time, due to the strong chemical bonding or interfacial interaction between the KDS material and metals such as copper, it can achieve extremely low surface roughness (Ra<0.1um / 0.2um, Rz<4um) after desmearing treatment, while still maintaining high adhesion to subsequent metal plating layers (>5N / cm). This characteristic of "high adhesion even with low roughness" directly breaks through the technical bottleneck of traditional processes, making it possible to manufacture ultra-fine lines with low loss L / S=2 / 2μm, significantly reducing skin effect loss in high-frequency signal transmission, and supporting laser patterning without causing charring problems.

[0303] 4. Flexible and diverse applications, strong process adaptability: The adjustability of the formulation of this invention allows for precise control of the material's rheological properties, curing behavior, and final form by adjusting the type of resin, molecular weight, filler content, and possible addition of flow-adjusting resins. Therefore, the composite dielectric sheet material of this invention can be manufactured into various product forms as needed, such as single-layer film (KDS), resin-clad copper foil (KDS-RCC), or combined with prepreg (KDS-GCP). Furthermore, it can also be formulated into a slurry form for processes such as overlay, via plugging, and planarization. Its excellent dielectric properties also allow it to be used as an embedded capacitor material. This flexibility enables this invention to adapt to various processing techniques such as coating, lamination, printing, and filling, meeting diverse needs from substrate manufacturing to packaging integration.

[0304] The present invention also provides a flip-chip ball grid array (FCBGA) packaging structure.

[0305] In one embodiment, the packaging structure includes a core layer and a stacked structure disposed on the core layer, wherein the stacked structure includes a dielectric layer formed by curing the composite dielectric sheet fabric described in any of the preceding claims.

[0306] The core advantage of applying the composite dielectric sheet material of this invention to the FCBGA packaging structure lies in the fact that the dielectric layer formed after the composite dielectric sheet material is cured can provide the packaging structure with superior comprehensive performance that is difficult to achieve with existing technologies. Specifically, the ultra-low dielectric loss (Df) characteristic of this dielectric layer can significantly reduce the attenuation of high-frequency signals during transmission, ensuring the signal integrity of high-speed chips such as CPUs and GPUs; its low coefficient of thermal expansion (CTE) characteristic can effectively alleviate the stress mismatch problem between the chip and the substrate during thermal cycling, improving the long-term reliability of the packaging structure; and its excellent adhesion to metal lines such as copper provides a solid foundation for the semi-additive process (SAP) to manufacture ultra-fine lines.

[0307] In some embodiments of the present invention, the dielectric layer in the multilayer structure can be configured as different functional layers according to specific application requirements. For example:

[0308] When used as a build-up material, the composite dielectric sheet of the present invention can replace the traditional multilayer adhesive film, and through multiple lamination, curing and metallization processes, a high-density multilayer interconnect structure can be constructed on the core layer.

[0309] When used as an embedded capacitor material, the composite dielectric sheet of the present invention can be sandwiched between two copper layers. Utilizing its controllable dielectric constant (Dk) and extremely low dielectric loss (Df), a high-performance embedded capacitor can be formed inside the packaging substrate, thereby achieving power supply decoupling, saving surface component space, and optimizing power supply network performance.

[0310] When used as a via-filling resin, the slurry form of the composition of the present invention can be used to fill through holes or blind holes in a substrate, forming a flat and dense filled structure after curing, providing a reliable planarization surface for subsequent circuit fabrication or component stacking.

[0311] It is understood that by using the composite dielectric sheet material of the present invention as the core dielectric material, the electrical performance and long-term reliability of the flip chip ball grid array packaging structure can be significantly improved, making it perfectly meet the stringent requirements of cutting-edge fields such as artificial intelligence (AI), high-performance computing and 5G / 6G communication for semiconductor packaging miniaturization, high density and high frequency and high speed.

[0312] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A composite dielectric sheet fabric, characterized in that, Including polymer resins and inorganic fillers, among which, The polymer resin includes: A film-forming resin, wherein the film-forming resin comprises a polymer with an aromatic heterocyclic backbone; The adhesive resin comprises an epoxy resin and a curing resin; and The dielectric modified resin comprises at least one of polyphenylene ether resin, bismaleimide resin, benzoxazine resin and hydrocarbon resin. The surface of the inorganic filler is modified with one or more functional groups selected from the group consisting of aniline, alkyl, nitrogen-containing functional groups on the main chain or branches, double-bonded functional groups, and epoxy groups.

2. The composite dielectric sheet fabric as described in claim 1, characterized in that, The polymer containing an aromatic heterocyclic backbone is selected from at least one of polyimide, modified polyimide, and modified bismaleimide.

3. The composite dielectric sheet fabric as described in claim 2, characterized in that, The polyimide includes at least one of liquid polyimide and thermoplastic polyimide.

4. The composite dielectric sheet fabric as described in claim 1, characterized in that, The epoxy resin is selected from at least one of glycidylamine epoxy resin, polyfunctional o-cresol glycidyl ether epoxy resin, phenol biphenyl epoxy resin, bisphenol F solid epoxy resin, isocyanate modified epoxy resin, naphthol epoxy resin, and phenol phenolic epoxy resin.

5. The composite dielectric sheet fabric as described in claim 1, characterized in that, The cured resin comprises a phenolic resin, wherein the phenolic resin is selected from at least one of linear phenol-formaldehyde resin and linear BPA-formaldehyde resin.

6. The composite dielectric sheet fabric as described in claim 5, characterized in that, The curing resin is also selected from at least one of benzoxazine, bismaleimide resin, reactive ester, and amine dicyandiamide curing agent.

7. The composite dielectric sheet fabric as described in claim 5, characterized in that, The content of the phenolic resin and the content of the epoxy resin satisfy the following formula: Phenolic resin content = (hydroxyl equivalent of phenolic resin / epoxy equivalent of epoxy resin) × epoxy resin content.

8. The composite dielectric sheet fabric as described in claim 1, characterized in that, The bonding resin further comprises a flowability adjusting resin selected from at least one of semi-crystalline epoxy resin, liquid bisphenol A type epoxy resin, liquid bisphenol F type epoxy resin, liquid bisphenol A-bisphenol F composite epoxy resin, liquid bisphenol S epoxy resin, liquid phenolic epoxy resin, and liquid phenolic resin.

9. The composite dielectric sheet fabric as described in claim 8, characterized in that, The flowability adjusting resin accounts for no more than 50% of the weight percentage of the binding resin.

10. The composite dielectric sheet fabric as described in claim 1, characterized in that, The hydrocarbon resin is a polyfunctional vinyl aromatic copolymer.

11. The composite dielectric sheet fabric as described in claim 1, characterized in that, The hydrocarbon resin includes modified hydrocarbon resin; and / or The bismaleimide resin includes modified bismaleimide; and / or The benzoxazine resin includes modified benzoxazine.

12. The composite dielectric sheet fabric as described in claim 11, characterized in that, The modified bismaleimide includes polyimide-modified bismaleimide.

13. The composite dielectric sheet fabric as described in claim 1, characterized in that, The inorganic filler is selected from at least one of silica, hollow silica, nano-silica derived from polyhedral oligomeric silsesquioxanes, boron nitride, perfluoroalkoxyalkane, and polytetrafluoroethylene.

14. The composite dielectric sheet fabric as described in claim 1, characterized in that, The composite dielectric sheet fabric also includes a solvent, which is selected from at least one of water, N-methylpyrrolidone, ethanol, acetone, ethyl acetate, n-butyl ether, methyl tert-butyl ether, dimethyl phthalate, butanone, dimethyl sulfoxide, n-butyl ketone, cyclohexanone, toluene, and xylene.

15. The composite dielectric sheet fabric as described in claim 1, characterized in that, The composite dielectric sheet fabric also includes additives, which are selected from at least one of leveling agents, dispersants, and defoamers.

16. The composite dielectric sheet fabric as described in any one of claims 1 to 15, characterized in that, The composite dielectric sheet fabric comprises, by weight percentage: 15% to 70% of the aforementioned polymeric resin; and The inorganic filler comprises 30% to 85%.

17. The composite dielectric sheet fabric as described in claim 16, characterized in that, The polymer resin contains, by weight percentage: 5% to 60% of the adhesive resin; 40% to 85% of the film-forming resin; and 1% to 55% of the dielectric-modified resin.

18. A method for preparing a composite dielectric sheet fabric, used to prepare the composite dielectric sheet fabric according to any one of claims 1 to 17, characterized in that, The preparation method includes the following steps: Preparation of resin slurry: The film-forming resin, the bonding resin and the dielectric modified resin are mixed in a first solvent to obtain a resin slurry; Preparation of filler slurry: The inorganic filler is mixed in a second solvent to obtain a filler slurry; and Mixing: The filler slurry is added to the resin slurry being stirred and mixed to obtain a composite dielectric sheet fabric mixed slurry.

19. The method for preparing the composite dielectric sheet fabric as described in claim 18, characterized in that, In the step of preparing the resin slurry, at least one additive selected from dispersants, defoamers, and leveling agents is pre-added to the first solvent; and / or In the step of preparing the filler slurry, at least one additive selected from dispersants, defoamers and leveling agents is pre-added to the second solvent.

20. The method for preparing the composite dielectric sheet fabric as described in claim 18, characterized in that, The mixing conditions of the preparation method include at least one of the following: The mixing speed during the preparation of the resin slurry is between 3600 rpm and 7200 rpm, the slurry temperature is not higher than 45°C, and the duration is between 60 and 120 minutes. The mixing speed during the preparation of the filler slurry is between 3600 rpm and 7200 rpm, the slurry temperature is not higher than 45°C, and the duration is between 60 and 120 minutes; and The mixing speed of the filler slurry and the resin slurry is between 3600 rpm and 7200 rpm, the slurry temperature is not higher than 45°C, and the duration is between 60 and 120 minutes.

21. The method for preparing the composite dielectric sheet fabric according to any one of claims 18 to 20, characterized in that, Following the mixing step, the preparation method further includes the following steps: Solvent removal: The composite dielectric sheet fabric mixture is subjected to solvent removal treatment to obtain a composite dielectric sheet fabric ink with a solid content between 64% and 98% and a viscosity between 10000 Pa·s and 50000 mPa·s.

22. The method for preparing the composite dielectric sheet fabric as described in claim 21, characterized in that, The solvent removal process includes: The composite dielectric sheet material mixing slurry is continuously stirred for 5 minutes to 3 hours at a temperature of 20℃ to 50℃ and a vacuum degree of less than 0.1MPa.

23. The method for preparing the composite dielectric sheet fabric as described in claim 21, characterized in that, Following the solvent removal step, the preparation method further includes the following steps: Preparation of dry film: The composite dielectric sheet fabric ink is coated onto the substrate film and then cured to obtain the composite dielectric sheet fabric dry film.

24. The method for preparing the composite dielectric sheet fabric as described in claim 23, characterized in that, The curing process includes: The ink on the composite dielectric sheet is dried for 30 seconds to 30 minutes in a temperature range of 50°C to 120°C.

25. A method for manufacturing a circuit board, characterized in that, Includes the following steps: Provide substrate: Provide a circuit board substrate with the area to be added; Applying composite dielectric sheet fabric: Applying the composite dielectric sheet fabric as described in any one of claims 1 to 17 to the region of the circuit board substrate to be added to form an added structure; Surface treatment: The added-layer structure is subjected to surface treatment; Metallization: Metal lines are fabricated on the surface of the added-layer structure.

26. The method for manufacturing a circuit board as described in claim 25, characterized in that, When using composite dielectric sheet ink, the steps for applying the composite dielectric sheet include: Preparation of dry film: The composite dielectric sheet fabric ink is coated on a carrier and dried at a temperature range of 50°C to 120°C for 30 seconds to 30 minutes to obtain a composite dielectric sheet fabric dry film, wherein the carrier is a substrate film or a copper foil layer. Bonding: The composite dielectric sheet dry film is hot-pressed onto the circuit board substrate at a temperature range of 50°C to 150°C and maintained for 30 seconds to 30 minutes; and Curing: The composite dielectric sheet is cured on the circuit board substrate at a temperature range of 120°C to 250°C for 10 minutes to 5 hours to form the added-layer structure.

27. The method for manufacturing a circuit board as described in claim 25, characterized in that, When using a composite dielectric sheet dry film, the steps for applying the composite dielectric sheet include: Bonding: The composite dielectric sheet dry film is hot-pressed onto the circuit board substrate at a temperature range of 50°C to 150°C and maintained for 30 seconds to 30 minutes; and Curing: The composite dielectric sheet is cured on the circuit board substrate at a temperature range of 120°C to 250°C for 10 minutes to 5 hours to form the added-layer structure.

28. The method for manufacturing a circuit board as described in claim 26 or 27, characterized in that, Prior to performing the surface treatment step, the preparation method further includes: Carrier removal: Remove the carrier from the surface of the dry film of the composite dielectric sheet. When the carrier is a substrate film, it is removed by peeling. When the carrier is a copper foil layer, it is removed by etching.

29. The method for manufacturing a circuit board as described in claim 25, characterized in that, The pull-out force of the metal circuit and the added-layer structure formed in the metallization process is not less than 5 N / cm.

30. A method for manufacturing a circuit board, characterized in that, Includes the following steps: Provide substrate: Provide a circuit board substrate with areas to be drilled; Applying composite dielectric sheet fabric: Applying the composite dielectric sheet fabric as described in any one of claims 1 to 17 to the area to be drilled on the circuit board substrate to form a dielectric layer; Drilling: Hole structures are formed on the circuit board substrate and the dielectric layer by means of laser drilling or mechanical drilling; Adhesive removal: The hole structure is subjected to adhesive removal treatment to modify the edges of the hole structure and remove drilling residue; Metallization process: The surfaces of the hole structure and the dielectric layer after the adhesive removal process are metallized to form metal lines on the hole walls of the hole structure and the surface of the dielectric layer.

31. The method for manufacturing a circuit board as described in claim 30, characterized in that, When using composite dielectric sheet ink, the steps for applying the composite dielectric sheet include: Preparation of dry film: The composite dielectric sheet fabric ink is coated on a carrier and dried at a temperature range of 50°C to 120°C for 30 seconds to 30 minutes to obtain a composite dielectric sheet fabric dry film, wherein the carrier is a substrate film or a copper foil layer. Bonding: The composite dielectric sheet dry film is hot-pressed onto the circuit board substrate at a temperature range of 50°C to 150°C and maintained for 30 seconds to 30 minutes; and Curing: The composite dielectric sheet is cured on the circuit board substrate at a temperature range of 120°C to 250°C for 10 minutes to 5 hours to form the added-layer structure.

32. The method for manufacturing a circuit board as described in claim 30, characterized in that, When using a composite dielectric sheet dry film, the steps for applying the composite dielectric sheet include: Bonding: The composite dielectric sheet dry film is hot-pressed onto the circuit board substrate at a temperature range of 50°C to 150°C and maintained for 30 seconds to 30 minutes; and Curing: The composite dielectric sheet is cured on the circuit board substrate at a temperature range of 120°C to 250°C for 10 minutes to 5 hours to form the added-layer structure.

33. The method for manufacturing a circuit board as described in claim 31 or 32, characterized in that, Prior to performing the drilling step, the preparation method further includes: Carrier removal: Remove the carrier from the surface of the dry film of the composite dielectric sheet. When the carrier is a substrate film, it is removed by peeling. When the carrier is a copper foil layer, it is removed by etching.

34. The method for manufacturing a circuit board as described in claim 30, characterized in that, After the adhesive removal process, the surface roughness Ra of the dielectric layer is no greater than 0.2 μm and Rz is no greater than 4 μm.

35. The method for manufacturing a circuit board as described in claim 30, characterized in that, The peel strength between the metal line formed in the metallization process and the dielectric layer is not less than 5 N / cm.

36. A flip-chip ball grid array packaging structure, characterized in that, The invention includes a core layer and a multilayer structure disposed on the core layer, wherein the multilayer structure comprises a dielectric layer formed by curing a composite dielectric sheet material according to any one of claims 1 to 17, the dielectric layer being configured as a build-up material, a capacitor material, or a pore-filling resin.

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