High-elongation dielectric composition, preparation method and application method thereof, and substrate

Abstract

The invention discloses a high-elongation dielectric composition, a preparation method and an application method thereof, and a substrate. The dielectric composition with high elongation rate comprises high-molecular resin and inorganic filler, wherein the polymer resin comprises bonding resin, and the bonding resin comprises epoxy resin and phenolic resin; the structural resin is selected from at least one of a polymer with a main chain containing an aromatic ring and / or a heterocyclic ring and a rubber polymer; the dielectric constant of the inorganic filler is not less than 2000 in the frequency range of 1kHz to 1GHz. Through a specific synergistic resin system, the high dielectric constant and the high elongation rate are achieved at the same time, the excellent melt viscosity, the excellent heat resistance, the low thermal expansion coefficient and the low hygroscopicity are achieved, and the defects of layering and plate explosion caused by poor fluidity, poor mechanical performance and mismatching of thermal stress in the manufacturing process of an existing high-Dk material are overcome.

Description

Technical Field

[0001] This invention relates to the field of dielectric property modification technology, and particularly to a high elongation dielectric composition, its preparation method, application method, and a substrate. Background Technology

[0002] The dielectric constant (Dk) is a key parameter measuring a material's ability to store electrical energy. In printed circuit boards (PCBs) and high-frequency electronics, materials with high Dk values ​​offer numerous advantages, including storing more electrical energy, improving signal integrity and timing control, enhancing power integrity and power transmission stability, and facilitating miniaturization and high-density layout of electronic devices. Therefore, high Dk materials play a crucial role in telecommunications equipment, medical imaging, aerospace, data centers, and even consumer electronics.

[0003] Currently, the main PCB materials on the market include laminates such as FR-4, Isola, and Taconic. However, the dielectric constant (Dk) values ​​of these traditional materials are typically in the range of 4.2 to 5.4, which is insufficient to meet the demands of the rapidly evolving modern electronic technology. To obtain higher Dk values, existing technologies usually employ the addition of high-dielectric ceramic fillers to the polymer matrix, but this approach faces a series of significant challenges.

[0004] First, the coefficient of thermal expansion (CTE) of high-dk materials often does not match that of other layers such as copper foil. During high-temperature processes such as reflow soldering, thermal stress can easily lead to cracks, deformation, and even serious delamination and board breakage problems. Second, many high-dk materials are highly sensitive to moisture. Moisture absorption not only alters electrical properties but also significantly exacerbates the risk of delamination and board breakage at high temperatures. Third, the excessive use of inorganic fillers to achieve high Dk values ​​often results in excessively high melt viscosity, leading to poor flowability during bonding and lamination processes. This makes it difficult to fully fill the microstructure of the substrate surface, affecting interfacial adhesion. More importantly, high filler content can also cause a sharp deterioration in the mechanical properties of the material (such as elongation), making the material brittle and unable to meet the application requirements of flexible electronics.

[0005] Therefore, how to develop a new type of dielectric material that achieves a high dielectric constant while also possessing suitable melt viscosity and processing fluidity, excellent mechanical properties (especially high elongation), high peel strength, high heat resistance (high glass transition temperature), low coefficient of thermal expansion, and low hygroscopicity has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] The main objective of this invention is to propose a high elongation dielectric composition that aims to solve the technical contradiction in existing dielectric materials where it is difficult to achieve both high dielectric constant and high elongation. It also provides excellent melt viscosity, heat resistance (high glass transition temperature), high peel strength, low coefficient of thermal expansion, and low hygroscopicity, thereby overcoming the defects of existing materials such as delamination and delamination caused by poor flowability, poor mechanical properties, easy moisture absorption, and thermal stress mismatch during the manufacturing process.

[0007] To achieve the above objectives, the present invention provides a high elongation dielectric composition comprising a polymer resin and an inorganic filler, wherein,

[0008] The polymer resin includes:

[0009] The adhesive resin comprises epoxy resin and phenolic resin; and

[0010] The structural resin is selected from at least one of polymers whose main chain contains aromatic rings and / or heterocycles and rubber-like polymers;

[0011] The dielectric constant of the inorganic filler is not less than 2000 in the frequency range of 1 kHz to 1 GHz, and 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 structural resin is selected from at least one of polyimide, poly(p-phenylenebenzodioxazole), polybenzimidazole, benzoxazine, bismaleimide, and bismaleimide triazine.

[0013] In one embodiment, the benzoxazine is selected from at least one of bisphenol A benzoxazine, bisphenol F benzoxazine, MDA benzoxazine, DCPD benzoxazine, phenol benzoxazine, and DOPO benzoxazine.

[0014] In one embodiment, the polyimide is selected from at least one of liquid polyimide and thermoplastic polyimide.

[0015] In one embodiment, the bismaleimide is selected from at least one of diaminodiphenylmethane modified bismaleimide, biphenyl-containing bismaleimide, high-performance thermoplastic resin blended toughened modified bismaleimide, isopropyl-p-phenylene-containing bismaleimide, PI modified bismaleimide, and cyanate ester modified bismaleimide.

[0016] In one embodiment, the polymer whose main chain comprises aromatic rings and / or heterocycles has a glass transition temperature of not less than 130°C.

[0017] In one embodiment, the rubber polymer is selected from at least one of natural rubber, nitrile rubber, styrene-butadiene rubber, chloroprene rubber, ethylene propylene diene monomer (EPDM) rubber, modified EPDM rubber, thermoplastic EPDM rubber, acrylic rubber, fluororubber, EPDM rubber, polyurethane rubber, and silicone rubber.

[0018] In one embodiment, the epoxy resin is selected from at least one of glycidylamine epoxy resin, phenoxy resin, polyfunctional o-cresol glycidyl ether epoxy resin, phenol-biphenyl epoxy resin, bisphenol F solid epoxy resin, isocyanate modified epoxy resin, naphthol type epoxy resin, phenol-formaldehyde epoxy resin, 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.

[0019] In one embodiment, the phenolic resin is selected from at least one of linear phenol-formaldehyde resin and linear BPA-formaldehyde resin.

[0020] In one embodiment, the content of the phenolic resin and the content of the epoxy resin satisfy the following formula:

[0021] Phenolic resin content = (hydroxyl equivalent of phenolic resin / epoxy equivalent of epoxy resin) × epoxy resin content.

[0022] In one embodiment, the inorganic filler is selected from at least one of barium titanate, strontium titanate, and materials having a perovskite-like structure.

[0023] In one embodiment, in the perovskite-like material, the divalent cation may be replaced by at least one selected from monovalent and trivalent cations, and the tetravalent cation may be replaced by at least one selected from trivalent and pentavalent cations.

[0024] In one embodiment, the high elongation dielectric composition comprises, by weight percentage:

[0025] 15% to 50% of the aforementioned polymeric resin; and

[0026] 50% to 85% of the inorganic filler.

[0027] In one embodiment, the polymer resin comprises, by weight percentage:

[0028] 70% to 100% of the structural resin; and

[0029] 0% to 30% of the adhesive resin.

[0030] In one embodiment, the high elongation dielectric composition further comprises 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.

[0031] In one embodiment, the high elongation dielectric composition further comprises an additive, which includes at least one of a leveling agent, a dispersant, and a defoamer.

[0032] In one embodiment, the solvent content is 0.5 to 10 times the total weight of the polymer resin; and / or

[0033] The content of the additive is 0.5% to 5% by weight of the total weight of the polymer resin.

[0034] The present invention also provides a method for preparing a high elongation dielectric composition, for preparing the high elongation dielectric composition described in any of the preceding claims, the preparation method comprising the following steps:

[0035] Preparation of resin slurry: The polymer resin is mixed in a first solvent to obtain a resin slurry;

[0036] Preparation of filler slurry: The inorganic filler is mixed in a second solvent to obtain a filler slurry; and

[0037] Mixing: The filler slurry is added to the resin slurry under stirring and mixed to obtain a dielectric composition ink with high elongation.

[0038] In one embodiment, in the step of preparing the resin slurry, at least one additive selected from leveling agents, dispersants and defoamers is pre-added to the first solvent;

[0039] and / or

[0040] In the step of preparing the filler slurry, at least one additive selected from leveling agents, dispersants and defoamers is pre-added to the second solvent.

[0041] In one embodiment, the total content of the first solvent and the second solvent is 0.5 to 10 times the total weight of the polymer resin; and / or

[0042] The total content of the additives is 0.5% to 5% by weight of the total weight of the polymer resin.

[0043] In one embodiment, the mixing conditions include at least one of the following:

[0044] The mixing speed during the preparation of the resin slurry is 3600 rpm to 7200 rpm, the slurry temperature is not higher than 45°C, and the duration is between 10 minutes and 60 minutes.

[0045] The mixing speed during the preparation of the filler slurry is 3600 rpm to 7200 rpm, the slurry temperature is not higher than 45°C, and the duration is between 10 minutes and 60 minutes; and

[0046] The mixing speed when mixing the filler slurry and the resin slurry is 3600 rpm to 7200 rpm, the slurry temperature is not higher than 45°C, and the duration is between 60 minutes and 120 minutes.

[0047] In one embodiment, after the mixing step, the preparation method further includes:

[0048] Preparation of dry film: The high elongation dielectric composition ink is coated onto the substrate film and cured to obtain a high elongation dielectric composition dry film.

[0049] In one embodiment, the curing process includes:

[0050] The high elongation dielectric composition ink is dried in a temperature range of 50°C to 120°C for 3 to 30 minutes.

[0051] This invention also proposes a method for applying composite dielectric sheet fabric, comprising the following steps:

[0052] Provide the target carrier;

[0053] Application of the composition: applying the high elongation dielectric composition described in any one of the preceding claims to the surface of the target carrier; and

[0054] Curing: The high elongation dielectric composition applied to the target carrier is cured to form a dielectric layer on the surface of the target carrier.

[0055] In one embodiment, the curing process includes heating continuously for 15 minutes to 5 hours within a temperature range of 120°C to 220°C.

[0056] In one embodiment, when a high-elongation dielectric composition in ink form is used, the step of applying the composition includes:

[0057] Coating: Applying a high-elongation dielectric composition ink to the surface of the target carrier by means of dip coating, screen printing, pad printing, stencil printing, spraying, or doctor blade printing; and

[0058] Solvent removal: Dry the high elongation dielectric composition ink coated on the surface of the target carrier at a temperature range of 50°C to 120°C and maintain for 3 to 30 minutes to form the dielectric layer.

[0059] In one embodiment, when a high elongation dielectric composition in dry film form is used, the step of applying the composition includes:

[0060] Bonding: A high elongation dielectric composition dry film is hot-pressed onto the surface of the target carrier at a temperature range of 70°C to 150°C and a pressure of not less than 0.4 MPa for 30 seconds to 5 minutes to form the dielectric layer.

[0061] In one embodiment, the bonding is performed under a vacuum of less than 0.1 MPa.

[0062] In one embodiment, the target carrier is selected from one of polyester film, polyimide film, copper foil, FR4 substrate and silicon wafer.

[0063] The present invention also proposes a substrate comprising:

[0064] Substrate body; and

[0065] A dielectric layer disposed on the surface of the substrate body, the dielectric layer being formed by curing a high elongation dielectric composition as described in any of the preceding claims.

[0066] The high elongation dielectric composition of this application has the following beneficial effects:

[0067] 1. Excellent dielectric and electrical properties: By employing a composite system of high dielectric constant inorganic fillers (such as barium titanate or perovskite structural materials, Dk2000~10000 or even higher) and polymer resins (structural resin main chain aromatic / heterocyclic / polymer / rubber polymer + epoxy-phenolic crosslinking network), the composition ensures that the Dk value can reach 24 at a frequency of 1kHz and the breakdown voltage is >150V (test unit is kV / mm), thereby providing efficient energy storage and signal integrity maintenance for RFID products, film capacitors and PCB substrate add-on.

[0068] 2. Excellent balance of mechanical flexibility and strength: Through the synergistic effect of structural resin (such as benzoxazine, Tg≥130℃) and binder resin (crosslinked according to the formula ratio), as well as the modification of functional groups on the filler surface (such as epoxy / double bond anchoring), a performance combination of 7.09GPa Young's modulus, 20% elongation and 50MPa is achieved, which can effectively withstand bending and thermal stress, avoid brittle fracture or delamination defects caused by high filling in existing materials, and support the miniaturization design of compact high-frequency circuits.

[0069] 3. Excellent thermal stability and processing tolerance: By controlling the ratio of main chain aromatic / heterocyclic polymer backbone and inorganic filler (50-85wt%), a low coefficient of thermal expansion (e.g., CTE of 28) and a glass transition temperature (Tg) as high as 215℃ are achieved, and the solder resistance*>10 (288℃) is also achieved. This ensures that the composition maintains dimensional stability and electrical consistency in high-temperature processes such as multilayer board lamination and reflow soldering, overcoming the problem of thermal expansion-induced board explosion of existing high Dk materials.

[0070] 4. Excellent processing fluidity and reliable interfacial adhesion: By selecting components such as liquid epoxy resin to adjust the melt viscosity, and combining the optimization of the crosslinking density of the phenolic-epoxy formula with the dispersion stability of auxiliary additives (0.5-5wt%), a comprehensive performance of 0.63% moisture absorption rate, 0.64 N / mm peel strength, and UL-94V0 flame retardant level is achieved. This allows the composition to maintain low loss and strong interfacial bonding in humidity-sensitive environments, facilitating uniform coating of carriers such as copper foil / FR4 substrates and improving the long-term reliability of medical / automotive electronics.

[0071] 5. Flexibility in processing and application and comprehensive balance of performance: By matching parameters such as solvent ratio (0.5 to 10 times) and multi-path morphology (ink / dry film), as well as the proportion gradient within the resin (70 to 100 wt% for structure and 0 to 30 wt% for bonding), it achieves compatibility with multiple processes such as dip coating / screen printing / vacuum bonding, while taking into account the contradictory requirements of high Dk and flexibility / stability / processability, providing a single material for multi-scenario solutions for high-frequency precision systems (such as data centers / aerospace). Attached Figure Description

[0072] 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.

[0073] Figure 1 This is a schematic flowchart of an embodiment of the method for preparing the high elongation dielectric composition of the present invention;

[0074] Figure 2 This is a schematic flowchart of an embodiment of the application method of the high elongation dielectric composition of the present invention.

[0075] 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

[0076] 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.

[0077] 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.

[0078] 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.

[0079] This invention provides a high elongation dielectric composition, aiming to solve the technical contradiction in existing dielectric materials that are difficult to balance high dielectric constant and high elongation. It also provides excellent melt viscosity, heat resistance (high glass transition temperature), high peel strength, low coefficient of thermal expansion and low hygroscopicity, so as to overcome the defects of existing materials such as delamination and delamination caused by poor flowability, poor mechanical properties, easy moisture absorption and thermal stress mismatch during the process.

[0080] In this embodiment of the invention, the high elongation dielectric composition comprises a polymer resin and an inorganic filler. The polymer resin provides the composition with excellent film-forming properties, adhesion to a substrate (such as copper foil), core mechanical flexibility (high elongation), and high heat resistance, while the inorganic filler serves as a functional filler, primarily used to provide a high dielectric constant.

[0081] Polymer resins include structural resins and adhesive resins.

[0082] Specifically, structural resins in the composition primarily act as a framework providing high heat resistance, high chemical resistance, and mechanical toughness. Their core function is to provide excellent thermal stability (high Tg point) and chemical inertness for the dielectric layer formed after final curing. In high-filler systems, the introduction of a large amount of inorganic filler (e.g., exceeding 50% by weight) is a prerequisite for achieving a high Dk value, but it can also easily lead to material brittleness and a significant decrease in elongation. The introduction of structural resins can form a tough framework in the cured network, effectively absorbing and dispersing stress, thereby significantly improving the overall mechanical toughness, crack resistance, and elongation of the composition.

[0083] The fundamental reason for the superior performance of structural resins is that they are selected from at least one of polymers whose main chain contains aromatic rings and / or heterocycles and rubber-like polymers.

[0084] Among these, polymers whose main chain contains aromatic rings and / or heterocycles have a molecular main chain composed of extremely stable aromatic rings or heterocycles with extremely high chemical bond energies and a dense structure. At the same time, due to their rigid main chain structure, the molecular chains are difficult to move, thus having a very high glass transition temperature (Tg). This ensures that the composite material will not soften, deform or degrade in performance when subjected to high-temperature processes (e.g., 180°C) such as multilayer lamination.

[0085] In some embodiments of the present invention, the polymers whose main chain comprises aromatic rings and / or heterocycles are selected from at least one of polyimide (PI), poly(p-phenylenebenzodioxazole) (PBO), polybenzimidazole (PBI), benzoxazine, bismaleimide, and bismaleimide triazine. The main chain structure of these polymers can be represented in the form of repeating units; for example, a typical structure of polyimide is an alternating linking of imide rings and aromatic bisphenyl groups.

[0086] Specifically, the polyimide can be selected from at least one of liquid polyimide and thermoplastic polyimide (TPI). In addition to high heat resistance and chemical resistance, these polyimide resins contain nonpolar and hydrophobic groups in their structure, which make them less prone to polarization in an electric field, thus helping to optimize dielectric properties.

[0087] Specifically, the benzoxazine referred to in this patent can be copolymerized with epoxy resin to improve the overall heat resistance and mechanical properties (such as hardness) of the composite resin of this invention. The benzoxazine can be selected from at least one of bisphenol A type benzoxazine, bisphenol F type benzoxazine, MDA type benzoxazine, DCPD type benzoxazine, phenol type benzoxazine, and DOPO type benzoxazine. These different types of benzoxazine can be used for functional regulation: for example, bisphenol F type has excellent toughness; MDA type has extremely high heat resistance (Tg≥200℃); DCPD type has excellent low dielectric loss (Df<0.0095); and DOPO type has excellent halogen-free flame retardancy.

[0088] Specifically, bisphenol A type benzoxazine is the most common standard type of benzoxazine. It is made by dehydration condensation of bisphenol A, paraformaldehyde, and aniline. It is a yellow solid at room temperature with a melting point of about 70°C. It can self-level when heated to 120°C. G(t) = 300-800s@210°C. The glass transition temperature Tg after curing is ≥170°C. The long-term service temperature is 180-200°C. It has a V1 flame retardant rating, a water absorption rate of <0.2%, and a Rockwell hardness of 120.

[0089] Bisphenol F type benzoxazine is a tough benzoxazine, which is produced by the dehydration condensation of bisphenol F, paraformaldehyde, and aniline. It is a yellow solid at room temperature with a melting point of about 60℃. It can self-level when heated to 120℃, with G(t) = 200-700s@210℃. The glass transition temperature Tg after curing is ≥170℃. It has a V1 flame retardant rating and is tougher than bisphenol A type benzoxazine. It is suitable for the preparation of composite materials.

[0090] MDA type benzoxazine is a high-heat-resistant benzoxazine, made by dehydration condensation of diaminodiphenylmethane, paraformaldehyde, and phenol. It is a brownish-yellow solid at room temperature with a melting point of about 90℃. It can self-level when heated to 120℃, with G(t) = 200-600s@210℃. The glass transition temperature Tg after curing is ≥200℃, the long-term service temperature is 200-220℃, the flame retardant rating is V1, and the residual carbon content in a nitrogen atmosphere is >50%@800℃. It is suitable for the preparation of products in high-temperature environments.

[0091] DCPD-type benzoxazine is a low-dielectric benzoxazine, produced by the dehydration condensation of dicyclopentadiene diphenol, paraformaldehyde, and aniline. It is a yellow solid at room temperature with a melting point of around 90℃. It can self-level when heated to 120℃, with a G(t) of 1000-3000s at 210℃. The glass transition temperature after curing is Tg ≥ 150℃. It has a V1 flame retardant rating. The dielectric constant Dk of dicyclopentadiene-type benzoxazine is < 3.0, and the dielectric loss Df is < 0.0095. Its excellent dielectric properties make it suitable for use in the field of copper-clad laminates for communication applications.

[0092] Phenolic benzoxazine is produced by the dehydration condensation of phenol, paraformaldehyde, and aniline. It is one of the simplest monocyclic benzoxazines. Due to its steric hindrance and small molecular structure, it has a melting point of about 40°C, low viscosity after melting, low curing temperature, and a glass transition temperature (Tg) ≥ 130°C after curing. It has a long-term service life, a V1 flame retardant rating, and is suitable for solvent-free low-viscosity systems, such as RTM molding.

[0093] DOPO type benzoxazine is a flame-retardant benzoxazine, produced by the dehydration condensation of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, benzoxazine, paraformaldehyde, and phenol. It is a yellow solid at room temperature with a melting point of about 90℃. It can self-level when heated to 120℃. The glass transition temperature (Tg) after curing is ≥150℃. It has a V0 flame retardancy rating, a phosphorus content >9.0%, and low smoke density. It is also halogen-free and can be used alone as a flame-retardant matrix resin or as a phosphorus-containing curing agent for epoxy resins. It can be applied to halogen-free flame-retardant composite materials and copper-clad laminates.

[0094] The bismaleimide (BMI) can be selected from at least one of diaminodiphenylmethane-modified bismaleimide, biphenyl-containing bismaleimide, isopropyl-p-phenylene-containing bismaleimide, PI-modified bismaleimide, and cyanate ester-modified bismaleimide. The introduction of BMI can further enhance the heat resistance and mechanical properties (such as hardness and toughness) of the composite resin by forming an interpenetrating network structure.

[0095] Specifically, the bismaleimide referred to in this patent can be copolymerized with epoxy resin to achieve synergistic effects by forming an interpenetrating network structure, thereby improving the overall heat resistance and mechanical properties (such as hardness and toughness) of the composite resin of this invention. Modified bismaleimide is preferred, and it can be, but is not limited to, diaminodiphenylmethane (DDM) modified bismaleimide, biphenyl-containing bismaleimide, isopropylparaben-type bismaleimide, PI modified bismaleimide, high-performance thermoplastic resin blended toughening modified bismaleimide, and cyanate ester modified bismaleimide.

[0096] Specifically, the structural formulas of polyimide (PI) and liquid polyimide (PI) are as follows:

[0097] High-performance thermoplastic resin blends toughened modified bismaleimides, such as polyimides, have the following structural formula:

[0098]

[0099] The structural formula of bismaleimide is:

[0100] Thermoplastic polyimide (TPI) type, its structural formula is:

[0101] Among these, modified bismaleimide resin and polyimide contain more non-polar 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.

[0102] The above materials have high chemical resistance, high Tg point, and film-forming properties.

[0103] The structural formula of poly(p-phenylenebenzodioxazole) is:

[0104] The structural formula of polybenzimidazole is:

[0105] The structural formula of benzoxazine is:

[0106] In addition, the structural formula of bismaleimide triazine can be referenced from bismaleimide.

[0107] In some embodiments, the glass transition temperature (Tg) of polymers whose main chain comprises aromatic rings and / or heterocyclic rings is not lower than 130°C. Setting this Tg range is crucial to ensuring the heat resistance of the material. If the Tg is lower than 130°C, the material may not be able to withstand subsequent high-temperature processes such as PCB lamination or reflow soldering (typically >200°C), easily softening and deforming, leading to decreased reliability. The structural resins selected in this invention all possess excellent heat resistance. For example, the phenolic benzoxazine used in specific embodiments has a cured Tg of not lower than 130°C; the MDA-type benzoxazine has a Tg of not lower than 200°C; and the bisphenol A-type benzoxazine has a Tg of not lower than 170°C.

[0108] The bonding resin is a core component that enhances the crosslinking density, pressure resistance, heat resistance, chemical resistance, and adhesion to the substrate (such as copper foil) of the composition. Its main function is to form a dense, high-strength network structure through a curing reaction, which crosslinks with functional groups on the surface of other resins (such as structural resins) and fillers.

[0109] Furthermore, the structural resin can also be a rubber-based polymer to maximize the material's flexibility. Rubber-based polymers have highly stretchable molecular chains, which are a major source of high elongation. As specific, non-limiting examples, the rubber-based polymer may be selected from at least one of natural rubber, nitrile rubber, styrene-butadiene rubber, chloroprene rubber, ethylene propylene diene monomer (EPDM) rubber, modified EPDM rubber, thermoplastic EPDM rubber, acrylic rubber, fluororubber, EPDM rubber, polyurethane rubber, and silicone rubber.

[0110] Specifically, the structural formula of natural rubber is:

[0111] The structural formula of nitrile rubber is:

[0112] The structural formula of styrene-butadiene rubber is:

[0113] The structural formula of chloroprene rubber is:

[0114] The structural formulas of binary ethylene propylene rubber, modified ethylene propylene rubber, and thermoplastic ethylene propylene rubber are as follows:

[0115] The structural formula of acrylic rubber is:

[0116] The structural formula of fluororubber is:

[0117] The structural formula of ethylene propylene diene monomer (EPDM) rubber is:

[0118] The structural formula of polyurethane rubber is:

[0119] The structural formula of silicone is:

[0120] It is worth noting that the structural resin can be selected from at least one of "polymers whose main chain contains aromatic rings and / or heterocyclic rings" and "rubber polymers". This means that in different embodiments of the present invention, the structural resin can be composed solely of the aforementioned aromatic / heterocyclic polymers with flexible segments (to balance heat and chemical resistance with a certain degree of elongation), or solely of the aforementioned rubber polymers (to maximize elongation), or it can be a blend or composite material of these two types of polymers. By adjusting the ratio of the two, fine control and optimized balance of the final composition in multiple dimensions such as rigidity, flexibility, heat resistance, and chemical resistance can be achieved.

[0121] In some embodiments of the present invention, the bonding resin comprises an epoxy resin and a phenolic resin as a crosslinking agent (curing agent).

[0122] To achieve precise control over the final performance, the epoxy resin used in this invention can be selected from at least one of the following: glycidylamine epoxy resin, phenoxy resin, polyfunctional o-cresol glycidyl ether epoxy resin, phenol-biphenyl epoxy resin, bisphenol F solid epoxy resin, isocyanate modified epoxy resin, naphthol epoxy resin, phenol-formaldehyde epoxy resin, 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 phenolic epoxy resin, and liquid phenolic resin. Among these, liquid resins (such as liquid bisphenol A-bisphenol F composite epoxy resin, liquid phenolic epoxy resin, etc.) help adjust the melt viscosity, increase the fluidity of the dielectric composition during bonding and pressing, thereby promoting sufficient wetting and interfacial bonding with the substrate surface, and helping the filler maintain a more uniform distribution during curing.

[0123] Specifically, the epoxy resin material used in this invention has an epoxy molecular weight of 2500 g / mol to 6000 g / mol.

[0124] 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.

[0125] The structural formula of the functional 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℃.

[0126] 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.

[0127] 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 type epoxy resin is characterized by low viscosity and flexibility. The properties of its cured product are almost identical to those of bisphenol A type epoxy resin. Adding it to PVB for copolymerization with its hydroxyl groups can effectively improve its corrosion resistance.

[0128] The structural formula of isocyanate-modified epoxy resin is:

[0129] 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 isocyanate-modified epoxy resin is characterized by low viscosity and flexibility. The properties of its cured product are almost identical to those of bisphenol A type epoxy resin. Adding it to PVB for copolymerization with its hydroxyl groups can effectively improve bond strength and peel strength.

[0130] The structural formula of naphthol-type epoxy resin is: 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 between 50 and 88°C. Among them, naphthol-type epoxy resins are superior to traditional bisphenol A type in terms of curing properties, heat resistance, and mechanical properties. Furthermore, due to its lower internal stress, it has a higher Tg and better adhesion. When added to structural resins and copolymerized with its hydroxyl groups, it can effectively improve the Tg point, bond strength, and peel strength.

[0131] 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. Phenolic epoxy resins have two or more epoxy groups in their molecular structure. Therefore, 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. Furthermore, the presence of two or more epoxy groups in the molecular structure of phenolic epoxy resins leads to a high crosslinking density in the cured product, resulting in excellent adhesive strength, heat resistance, and chemical resistance.

[0132] The structural formula of semi-crystalline epoxy resin is:

[0133] The structural formulas of liquid bisphenol A type epoxy resin and liquid bisphenol F type epoxy resin are as follows:

[0134] The structural formula of liquid bisphenol A-bisphenol F composite epoxy resin is:

[0135] The structural formula of liquid phenolic epoxy resin is:

[0136] The structural formula of liquid phenolic resin is:

[0137] Among the aforementioned epoxy resins, semi-crystalline epoxy resin, liquid bisphenol A type epoxy resin, liquid bisphenol F type epoxy resin, liquid bisphenol A-bisphenol F composite epoxy resin, and liquid bisphenol S epoxy resin have epoxy equivalents ranging from 140 to 214 g / eq, hydrolytic chlorine content less than 250 ppm, and viscosity at 25°C ranging from 1300 to 4500 mPa·s. These resins not only possess low viscosity and high crosslinking density, but also excellent adhesive strength, melt viscosity, heat resistance, and chemical resistance. Their main function is to control resin flowability and adhesion to the substrate, making them particularly suitable for glass substrates.

[0138] In some embodiments of the present invention, the phenolic resin is 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 (<0.6%) and low conductivity (<8 μS / cm), is beneficial for ensuring the stability of the curing reaction and the electrical insulation properties of the final dielectric layer.

[0139] 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.

[0140] 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.

[0141] In some embodiments, the content of phenolic resin and the content of epoxy resin satisfy the following formula:

[0142] Phenolic resin content = (hydroxyl equivalent of phenolic resin / epoxy equivalent of epoxy resin) × epoxy resin content.

[0143] 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. Therefore, the essence of the above formula is a mathematical conversion of the chemical equilibrium relationship that "the number of moles of phenolic hydroxyl groups ≈ the number of moles of epoxy groups".

[0144] 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.

[0145] 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. To ensure the most complete and efficient reaction, the ideal feed ratio should be as close as possible to a 1:1 ratio of the total molar number of phenolic hydroxyl groups to the total molar number of epoxy groups in the formulation. This stoichiometric method ensures the full progress of the cross-linking reaction, preventing the presence of excessive amounts of any one component that would result in a large number of unreacted functional groups remaining in the cured network. This leads to the highest cross-linking density in the final cured dielectric layer, resulting in superior heat resistance, chemical resistance, and the strongest mechanical strength and adhesion to the substrate.

[0146] Inorganic fillers are mainly used as functional components with high dielectric constants in the composition, and their Dk values ​​are much higher than those of polymer resins, which is the physical basis for achieving the high Dk (e.g., Dk>20) target of this invention. At the same time, inorganic fillers can also improve the mechanical properties of the dielectric layer formed by the composition (such as hardness, Young's modulus, tensile modulus, and flexural modulus).

[0147] In the present invention, the dielectric constant of the inorganic filler is not less than 2000 in the frequency range of 1 kHz to 1 GHz. The Dk value of the polymer resin matrix (such as epoxy, PI) in the composition is usually in the lower range of 3-5. In order to increase the Dk value of the composite material to be much higher than that of the matrix (greater than 24 or even higher), ferroelectric ceramic fillers with a Dk value as high as several thousand must be relied on. Therefore, limiting the Dk value of the inorganic filler to not less than 2000 is to ensure that the filler can serve as a "functional main body with a high dielectric constant", thereby achieving the high Dk goal of the present invention.

[0148] In some embodiments of the present invention, the inorganic filler is selected from at least one of barium titanate, strontium titanate, and materials with a perovskite-like structure. In the materials with a perovskite-like structure, the divalent cations (such as at the A site) can be replaced by at least one selected from monovalent cations and trivalent cations, and the tetravalent cations (such as at the B site) can be replaced by at least one selected from trivalent cations and pentavalent cations. Through this element doping and substitution, the dielectric properties of the material can be further regulated. Specifically, the cation substitution at the A site and the B site can be referred to the following examples:

[0149] I. Examples of divalent cation substitution at the A site

[0150] The A site of the perovskite-like structure material is usually occupied by divalent cations with a relatively large radius (such as Ca 2+ , Sr 2+ or Ba 2+ ) to provide lattice stability. By substituting with monovalent cations (such as Na + ) or trivalent cations (such as La 3+ ), the lattice distortion and dielectric polarization response can be regulated. This substitution needs to achieve charge compensation through partial replacement, such as introducing oxygen vacancies or adjusting the ratio (x value) to maintain overall electrical neutrality.

[0151] Examples of monovalent cation substitution:

[0152] Chemical composition: Based on CaTiO3, part of the Ca 2+ at the A site is replaced by Na + (monovalent) to form Na x Ca 1-x TiO3 (0 < x ≤ 0.5). When the typical x = 0.5, the structure is Na 0.5 Ca 0.5 TiO3, where Na + (ionic radius ) replaces Ca 2+ introducing lattice compression to enhance the dielectric constant.

[0153] Implementation method: The solid-phase synthesis method is adopted.

[0154] Example of trivalent cation substitution:

[0155] Chemical composition: For the A-site Ca 2+ Partially substituted with La 3+ (trivalent) to form La x / 2Ca 1-x TiO3 (0 < x ≤ 1), and when the typical x = 0.5, it is La 0.25 Ca 0.75 TiO3, where La 3+ (ionic radius ) introduces an excess of positive charge, which is compensated by oxygen vacancies (V_O^{··}) (charge balance: 2[La_{Ca}'] = [V_O^{··}]).

[0156] Implementation method: The sol-gel method is adopted.

[0157] II. Example of substitution of tetravalent cations at the B-site

[0158] The B-site is occupied by tetravalent cations with a smaller radius (such as Ti 4+ ) to coordinate the six-coordinated oxygen octahedron. By substituting trivalent cations (such as Al 3+ ) or pentavalent cations (such as Nb 5+ ), the octahedron tilt and electronic structure can be adjusted, affecting the dielectric loss. This substitution also requires charge compensation, such as introducing low-valence A-site ions or oxygen vacancies.

[0159] Example of trivalent cation substitution:

[0160] Chemical composition: Based on CaTiO3, for the B-site Ti 4+ Partially substituted with Al 3+ (trivalent) to form CaTi 1- x Al x O 3-x / 2 (0 < x ≤ 0.2), and when the typical x = 0.1, it is CaTi 0.9 Al 0.1 O 2.95 where Al 3+ (ionic radius ) replaces Ti 4+ Compensated by oxygen vacancies ([Al_{Ti}'] = [V_O^{··}] / 2).

[0161] Implementation method: The hydrothermal synthesis method is adopted.

[0162] Example of pentavalent cation substitution:

[0163] Chemical composition: Part of Ti at the B site 4+ is replaced by Nb 5+ (pentavalent) to form CaTi 1-x Nb x O 3+x / 2 (0 < x ≤ 0.1), typically CaTi 0.95 Nb 0.05 O 3.025 when x = 0.05, where Nb 5+ (ionic radius ) introduces positive charges, which are compensated by oxygen excess (2[Nb_{Ti}·] = [O_i”]).

[0164] Implementation method: Coprecipitation method is adopted.

[0165] In addition, in order to improve the interfacial compatibility between the inorganic filler (usually hydrophilic) and the polymer resin matrix (usually hydrophobic), prevent its agglomeration at high contents, and ensure their effective combination, the surface of the inorganic filler has been modified with specific functional groups. Specifically, the surface of the inorganic filler is modified with one or more functional groups selected from the following group: anilino group, alkyl group, functional groups containing nitrogen in the main chain or side chain, functional groups containing double bonds, and epoxy group. These functional groups can react with the active groups (such as hydroxyl group or epoxy group, etc.) in the polymer resin or form strong interactions (such as hydrogen bonds), thereby tightly anchoring the inorganic filler in the resin matrix, making the finally formed dielectric layer have more excellent mechanical properties and lower hygroscopicity. Among them, introducing hydrophobic functional groups such as "alkyl group" helps to reduce the hydrophilicity of the surface of the inorganic filler, thereby improving the moisture resistance of the material and reducing the moisture absorption rate.

[0166] In some embodiments, the high elongation dielectric composition comprises 15% to 50% by weight of the polymer resin, and 50% to z% of the inorganic filler.

[0167] This ratio is set to precisely balance the high Dk value and high elongation pursued by the present invention. The polymer resin is a continuous phase matrix that provides mechanical flexibility (elongation) and film-forming property. If the content is less than 15%, the resin is not sufficient to completely coat and bond a large amount of inorganic filler, resulting in brittle material, poor film-forming property, and a significant reduction in elongation. The inorganic filler is the core source for providing a high Dk value. If the content is less than 50%, the effect of increasing the Dk value is not obvious, and the high Dk target of the present invention cannot be met. If the content is higher than 85%, the proportion of filler in the system is too high, the viscosity rises sharply, it is difficult to process, and at the same time, the mechanical properties (especially elongation) will deteriorate severely and lose flexibility.

[0168] It should be noted that there is a typo in the original text where "50% to z%" should probably be "50% to 85%". The translation has been made based on the corrected understanding.In some embodiments, the polymer resin comprises, by weight percentage: 70% to 100% of the structural resin; and 0% to 30% of the binding resin.

[0169] The proportions of the components within this polymer resin are precisely designed to balance the material's mechanical toughness (derived from the structural resin) with its crosslinking density and adhesion (derived from the binder resin). The structural resin, as the main framework of the polymer system, is the functional core providing high elongation and heat resistance. To ensure the dielectric layer remains flexible and non-brittle while supporting up to 85% inorganic filler, the structural resin must dominate the entire polymer system (70% to 100%). The binder resin (epoxy and phenolic system) is key to providing high adhesion, high crosslinking density, and chemical resistance. By controlling its content within the range of 0% to 30%, precise control over adhesion and crosslinking degree can be achieved without excessively sacrificing the high elongation provided by the structural resin.

[0170] In some embodiments, the polymer resin further includes 0% to 20% by weight of a structural reinforcing resin. This structural reinforcing resin (e.g., a specific epoxy or phenolic resin with high functionality added in addition to the adhesive resin) is an optional component (0% to 20%), and its role is to further enhance the crosslinking density, pressure resistance, and heat resistance of the system, complementing and strengthening the function of the adhesive resin.

[0171] In some embodiments, the composition further comprises a solvent to improve the processability of the composition during preparation, storage, and application. The solvent 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. The solvent primarily acts as a carrier medium in the composition, its core function being to dissolve the polymer resin and uniformly disperse the inorganic filler, forming a homogeneous, stable liquid system (ink) with a suitable application viscosity.

[0172] In some embodiments, the dielectric composition of the present invention further comprises an additive, which includes at least one selected from leveling agents, dispersants, and defoamers. The addition of these additives is intended to optimize the physicochemical behavior of the composition during preparation and application. Specifically, the main function of the dispersant is to improve and stabilize the dispersion state of inorganic fillers in the resin matrix; the main function of the leveling agent is to improve the surface appearance of the composition during coating and film formation, eliminating defects such as orange peel and pinholes; the main function of the defoamer is to eliminate air bubbles introduced by high-speed stirring or shearing. In a specific embodiment, examples of additives that may be used include leveling agent BYK530, dispersant BYK2152, and defoamer BYK333.

[0173] In some embodiments, the solvent content is 0.5 to 10 times the total weight of the polymer resin; the additive content is 0.5 to 5% by weight of the total weight of the polymer resin. Specifically, if the solvent content is less than 0.5 times, the viscosity of the composition may be too high, making it impossible to dissolve or disperse the components; if it is more than 10 times, the solid content is too low, making it difficult to form a film layer of effective thickness. If the additive content is less than 0.5%, its effect on improving processability is not significant; if it is more than 5%, it may adversely affect the electrical or mechanical properties of the final dielectric layer.

[0174] In addition, please refer to Table 1, which shows the dielectric properties of the dielectric layer formed by the dielectric composition of the present invention.

[0175] No. Test Project unit Test methods control group This invention 1 Dielectric layer thickness um Precision measuring instruments and electron microscopy observation 12 12 2 Peel strength N / mm IPC TM-650 2.4.8c 0.7 0.9～1.2 3 Solder heat resistance ℃ Tin Dip Boiler Test >10(288℃) >10(288℃) 4 Dk(1kHz) — Network Vector Analyzer Measurement 21 24～31 5 Young's module GPa ASTM D-882A NA 7.09 6 elongation ％ ASTM D-882 1.3 2.0 7 Tensile strength MPa ASTM D-882A 120 50 8 CTE ppm / ℃ IPC TM-650 2.4.24.5 33 28 9 Tg ℃ IPC TM-650 2.4.24.4 160 215 10 Moisture absorption rate ％ TM-650 2.6.2.1 0.5 0.63 11 UL — UL-94 V0 V0 12 Breakdown voltage kV / mm IPCTM-650 2.5.6.2.A >150V >150V

[0176] As can be seen from the above embodiments, the high elongation dielectric composition of this application has the following beneficial effects:

[0177] 1. Excellent dielectric and electrical properties: By employing a composite system of high dielectric constant inorganic fillers (such as barium titanate or perovskite structural materials, Dk2000~10000 or even higher) and polymer resins (structural resin main chain aromatic / heterocyclic polymers / rubber polymers + epoxy-phenolic crosslinking network), the composition ensures that the Dk value can reach 24 at a frequency of 1kHz and the breakdown voltage is >150V (test unit is kV / mm), thereby providing efficient energy storage and signal integrity maintenance for RFID products, film capacitors and PCB substrate add-on layers.

[0178] 2. Excellent balance of mechanical flexibility and strength: Through the synergistic effect of structural resin (such as benzoxazine, Tg≥130℃) and binder resin (crosslinked according to the formula ratio), as well as the modification of functional groups on the filler surface (such as epoxy / double bond anchoring), a performance combination of 7.09GPa Young's modulus, 20% elongation and 50MPa is achieved, which can effectively withstand bending and thermal stress, avoid brittle fracture or delamination defects caused by high filling in existing materials, and support the miniaturization design of compact high-frequency circuits.

[0179] 3. Excellent thermal stability and processing tolerance: By controlling the ratio of main chain aromatic / heterocyclic polymer backbone and inorganic filler (50-85wt%), a low coefficient of thermal expansion (e.g., CTE of 28) and a glass transition temperature (Tg) as high as 215℃ are achieved, and the solder resistance is >10 (288℃). This ensures that the composition maintains dimensional stability and electrical consistency in high-temperature processes such as multilayer board lamination and reflow soldering, overcoming the problem of thermal expansion-induced board explosion of existing high Dk materials.

[0180] 4. Excellent processing fluidity and reliable interfacial adhesion: By selecting components such as liquid epoxy resin to adjust the melt viscosity, and combining the optimization of the crosslinking density of the phenolic-epoxy formula with the dispersion stability of auxiliary additives (0.5-5wt%), a comprehensive performance of 0.63% moisture absorption rate, 0.64 N / mm peel strength, and UL-94V0 flame retardant level is achieved. This allows the composition to maintain low loss and strong interfacial bonding in humidity-sensitive environments, facilitating uniform coating of carriers such as copper foil / FR4 substrates and improving the long-term reliability of medical / automotive electronics.

[0181] 5. Flexibility in processing and application and comprehensive balance of performance: By matching parameters such as solvent ratio (0.5 to 10 times) and multi-path morphology (ink / dry film), as well as the proportion gradient within the resin (70 to 100 wt% for structure and 0 to 30 wt% for bonding), it achieves compatibility with multiple processes such as dip coating / screen printing / vacuum bonding, while taking into account the contradictory requirements of high Dk and flexibility / stability / processability, providing a single material for multi-scenario solutions for high-frequency precision systems (such as data centers / aerospace).

[0182] The present invention also provides a method for preparing a high elongation dielectric composition, for preparing the high elongation dielectric composition described in any of the foregoing embodiments.

[0183] like Figure 1 As shown, in some embodiments, the preparation method includes the following steps:

[0184] S1. Preparation of resin slurry: The polymer resin is mixed in a first solvent to obtain a resin slurry.

[0185] This step aims to form a homogeneous, phase-separated resin slurry as a basis for subsequent filler introduction. Specifically, polymeric resins (including structural resins, binding resins, and optional structurally reinforcing resins) are mixed in a first solvent. The structural resin provides a heat-resistant framework (e.g., benzoxazine), the binding resin ensures cross-linking (e.g., epoxy-phenolic resin), and the first solvent is selected from N-methylpyrrolidone or acetone.

[0186] In a preferred embodiment, to improve the fluidity and stability of the slurry, at least one additive selected from dispersants, defoamers, and leveling agents can be pre-added to 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 dispersant BYK-2152, defoamer BYK-530, and leveling agent BYK-333. The pre-addition of these additives can wet the surface of the resin particles and effectively prevent the resin component from agglomerating and settling in the solvent through electrostatic repulsion or steric hindrance effects, thereby ensuring the uniformity and storage stability of the slurry.

[0187] Specifically, the mixing process for preparing resin slurry can be achieved using high-speed mixing equipment such as a homogenizer. Of course, the homogenizer can also be replaced by a ball mill, emulsifier, high-speed mixer, or collider to achieve uniform mixing.

[0188] In some embodiments, the mixing speed for preparing the resin slurry is between 3600 rpm and 7200 rpm. To prevent the resin stability from being affected by high-speed shear heating (e.g., premature reaction of the epoxy-phenolic system in the binder resin), 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 duration is between 10 minutes and 60 minutes (e.g., 30 minutes) to ensure the formation of a homogeneous and stable resin slurry.

[0189] The reason for setting the above parameters is as follows:

[0190] Rotation speed (3600 to 7200 rpm) provides sufficient shear force to disperse resin particles; if the rotation speed is too low, insufficient mixing may occur, leading to phase separation.

[0191] The temperature (not higher than 45℃) is to avoid resin pre-crosslinking. If it is higher than 45℃, the bonding resin (such as epoxy / phenolic system) is prone to premature reaction, which shortens the storage period.

[0192] The duration (10 to 60 minutes) is to balance efficiency and thoroughness. If the duration is too short, the slurry may be unevenly dispersed, while if it is too long, it will increase energy consumption.

[0193] S2. Preparation of filler slurry: The inorganic filler is mixed in a second solvent to obtain a filler slurry.

[0194] This step aims to obtain a non-agglomerated filler slurry, ensuring uniform dispersion of the inorganic filler and avoiding uneven subsequent compounding. Specifically, surface-modified inorganic fillers (such as epoxy-modified barium titanate) are mixed in a second solvent. The inorganic filler provides a dielectric contribution (Dk 2000–10000, or even higher), and the surface-modified functional groups improve interfacial compatibility. The second solvent is selected from ethanol or acetone.

[0195] In a preferred embodiment, at least one additive selected from dispersants, defoamers, and leveling agents may be pre-added to the second solvent before the inorganic filler is added to improve the dispersion efficiency of the filler. This process can employ similar equipment and process parameters as step S1, for example, using a homogenizer at a rotation speed of 3600 rpm to 7200 rpm and a temperature not exceeding 45°C, for a duration between 10 and 60 minutes (e.g., 30 minutes) to ensure that the inorganic filler particles are sufficiently wetted and uniformly dispersed.

[0196] 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 are 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.

[0197] Furthermore, the total content of the first solvent and the second solvent is 0.5 to 10 times the total weight of the polymer resin; the total content of the additives is 0.5 to 5% by weight of the total weight of the polymer resin. These content ranges are limited because: if the solvent content is less than 0.5 times, the viscosity of the composition may be too high, making it impossible to dissolve or disperse the components; if the solvent content is more than 10 times, the solid content is too low, making it difficult to form a film of effective thickness.

[0198] S3. Mixing: The filler slurry is added to the resin slurry being stirred and mixed to obtain the dielectric composition with high elongation.

[0199] This step aims to achieve a uniform organic-inorganic composite to form the final slurry. 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 a homogenizer to ensure that the filler particles achieve optimal dispersion in the final resin composition.

[0200] The final mixing step uses a rotation speed of 3600 rpm to 7200 rpm, a temperature not exceeding 45°C, and a duration of 60 to 120 minutes (e.g., 90 minutes) to obtain a dielectric composition ink with high elongation. The rotation speed and temperature settings are the same as in S10 / S20 to ensure shear force and thermal control; the extended time of 60-120 minutes ensures that the high proportion of inorganic filler particles achieves optimal dispersion in the final resin composition.

[0201] Following the mixing step, the preparation method of this application may further include a post-processing step:

[0202] S4. Preparation of dry film: The high elongation dielectric composition is coated onto the substrate film and then subjected to solvent removal treatment to obtain a high elongation dielectric composition dry film.

[0203] This step aims to transform the high elongation dielectric composition, which is in the form of a slurry prepared in the previous step, into a solid dry film (i.e., a high elongation dielectric composition dry film) with a specific thickness, uniformity, and easy to apply subsequently by hot pressing.

[0204] Specifically, a high-elongation dielectric composition ink is uniformly coated onto a substrate film using methods such as doctor blade printing, dip coating, or screen printing. This substrate film is typically a release film, such as a PET (polyethylene terephthalate) film.

[0205] After coating, the substrate film coated with the composition ink is cured. This curing process is preferably a drying procedure performed in a hot air oven. The procedure includes drying the high elongation dielectric composition ink at a temperature range of 50°C to 120°C for 3 to 30 minutes.

[0206] The reason for limiting the above process conditions is as follows:

[0207] Temperature (50℃ to 120℃): Setting the lower limit of the temperature to 50℃ ensures that solvent molecules have sufficient energy to escape efficiently from the coating. If the temperature is below 50℃, the solvent evaporation rate will be too slow, potentially leaving solvent residue inside the film layer, resulting in a soft, sticky, or mechanically weak final dry film. Controlling the upper limit of the temperature to 120℃ ensures effective solvent evaporation while preventing significant premature cross-linking of the adhesive resin (epoxy / phenolic system). If the temperature is too high, the dry film may over-cur, resulting in a loss of necessary fluidity during subsequent hot-pressing onto the target carrier, affecting the bonding effect.

[0208] Time (3 to 30 minutes): Setting the lower limit of the time to 3 minutes ensures sufficient time for the solvent inside the film to evaporate completely, forming a stable solid film. If the baking time is too short, incomplete curing will occur, affecting the operability of the dry film. Controlling the upper limit of the time to 30 minutes ensures complete solvent removal while also considering the efficiency of industrial production.

[0209] The present invention also proposes a method for applying a composite dielectric sheet material, which uses the high elongation dielectric composition described in any of the foregoing embodiments to construct a dielectric layer with high dielectric constant, high elongation and high reliability on a target carrier.

[0210] like Figure 2 As shown, in one embodiment, the application method includes the following steps:

[0211] S10. Provide target carrier: First, provide a target carrier to be processed.

[0212] This step aims to prepare the target carrier for processing, serving as the basis for subsequent application and curing. Specifically, a copper foil or FR4 substrate with a thickness of 12μm can be provided, with a clean and oil-free surface to ensure uniform dielectric layer adhesion. This target carrier is widely used in printed circuit board overlays, RFID products, or thin-film capacitors, etc. The thickness is controlled below 12μm to meet the requirements of high-precision, high-frequency circuits, while highlighting the dielectric optimization suitability of the dielectric composition of this invention for flexible carriers.

[0213] Alternatively, the target carrier may be selected from one of polyester film, polyimide film, copper foil, FR4 substrate and silicon wafer.

[0214] In a preferred embodiment, the surface of the target carrier may be cleaned, roughened, or plasma-treated before the composition is applied to remove surface contaminants and increase surface energy, thereby ensuring excellent adhesion of the subsequent dielectric layer.

[0215] S20. Applying the composition: Apply the high elongation dielectric composition described in any of the foregoing embodiments to the surface of the target carrier.

[0216] This step aims to uniformly apply a high-elongation dielectric composition to the target substrate to form an initial dielectric layer. The function of this step is to construct a high-Dk functional interface, ensuring signal propagation and energy storage; it occupies the starting point of the processing chain, providing the electrical and mechanical support foundation. The application of the composition is not limited to a specific form; for example, compositions in paste or ink form can be achieved through coating or dry film lamination.

[0217] In some embodiments, when a high elongation dielectric composition in ink form is used, step S20 is achieved through steps S21-S22:

[0218] S21. Coating: Applying a high elongation dielectric composition ink to the surface of the target carrier by means of dip coating, screen printing, pad printing, stencil printing, spraying or squeegee printing.

[0219] S22, Solvent Removal: Solvent Removal: Dry the high elongation dielectric composition ink coated on the surface of the target carrier at a temperature range of 50°C to 120°C for 3 to 30 minutes to form the dielectric layer. This step aims to remove most of the solvent in the composition before final curing, forming a gel-like or surface-dried coating.

[0220] Specifically, the target substrate can be placed in a hot air oven at 80°C for 10 minutes to remove the solvent and form a dense dielectric layer. The temperature setting of 50°C to 120°C is because: below 50°C, solvent evaporation is slow, resulting in a loose layer; above 120°C, resin pre-crosslinking occurs, affecting adhesion. The time setting of 3 to 30 minutes is to balance efficiency: less than 3 minutes results in more residual solvent, while more than 30 minutes increases energy consumption without significant benefit.

[0221] In other embodiments, when a high elongation dielectric composition in the form of a dry film is used, step S20 is performed by step S23.

[0222] S23. Bonding: At a temperature range of 70°C to 150°C and a pressure of not less than 0.4 MPa, a high elongation dielectric composition dry film is hot-pressed onto the surface of the target carrier for 30 seconds to 5 minutes to form the dielectric layer.

[0223] The reason for limiting the above bonding process conditions is that the temperature (70°C to 150°C) is intended to soften the resin system in the dry film, generating sufficient fluidity to wet and fill the microstructure of the target carrier surface, thereby achieving a firm physical adhesion; the pressure (not less than 0.4 MPa) is necessary to ensure close contact between the dry film and the target carrier and to eliminate interfacial air.

[0224] In a preferred embodiment, when using a vacuum laminator for lamination, the lamination operation is preferably performed under a vacuum level of less than 0.1 MPa. This ensures that air between the target carrier and the dry film is completely eliminated during the thermoforming process, preventing the formation of bubbles or voids. This helps to ensure uniform electrical properties of the dielectric layer (such as preventing localized breakdown).

[0225] S30. Curing: Curing the high elongation dielectric composition applied to the target carrier to form a dense, cross-linked dielectric layer with stable electrical and mechanical properties on the surface of the target carrier.

[0226] In some embodiments, the curing process includes heating continuously at a temperature range of 120°C to 220°C for 15 minutes to 5 hours to complete the curing of the resin network. The reason for limiting the above process conditions is that:

[0227] Temperature (120℃ to 220℃): This temperature range is necessary to ensure sufficient cross-linking of the bonding resin (epoxy / phenolic system) with the active groups in the structural resin. Below 120℃, the curing reaction is incomplete, resulting in a low Tg point, poor mechanical strength, and insufficient chemical resistance of the dielectric layer. Above 220℃, excessive oxidation or degradation of the polymer resin may occur, potentially causing thermal damage to certain sensitive target carriers (such as polyester films).

[0228] Time (15 minutes to 5 hours): Sufficient heating time is crucial to ensure the cross-linking reaction proceeds to completion and a stable three-dimensional network structure is formed. If the time is less than 15 minutes, curing will be insufficient; while if it is more than 5 hours, production efficiency will be significantly reduced without any additional performance gain.

[0229] It is understood that the dielectric layer formed by the above application method can be used to optimize the dielectric constant of the substrate material, or it can be used as a high dielectric constant layer to stabilize the signal and prevent signal bounce or mutual interference. It can also be used as a dielectric layer for thin film capacitors or RFID dielectric layers, and has wide application value in fields such as electromagnetics, medical imaging, aerospace and automotive electronics.

[0230] The present invention also provides a substrate, which is the final application product of the high elongation dielectric composition of the present invention, comprising a substrate body and a dielectric layer.

[0231] In one embodiment, the substrate body corresponds to the target carrier described in the aforementioned application method, and may be selected from one of polyester film, polyimide film, copper foil, FR4 substrate and silicon wafer.

[0232] A dielectric layer is disposed on the surface of the substrate body. This dielectric layer is formed by curing the high elongation dielectric composition described in any of the foregoing embodiments.

[0233] Specifically, the dielectric layer is a dielectric composition that, after being processed by the aforementioned application method, particularly after undergoing a thermosetting treatment at 120°C to 220°C for 15 minutes to 5 hours, forms a final cross-linked solid film.

[0234] It is understood that, since the dielectric layer inherits the core characteristics of the composition, the substrate (also known as the composite dielectric sheet) has the "high elongation" characteristic of the composite dielectric sheet, and at the same time possesses high dielectric constant, high heat resistance and excellent interfacial adhesion.

[0235] 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 dielectric composition with high elongation, characterized in that, Including polymer resins and inorganic fillers, among which, The polymer resin includes: The adhesive resin comprises epoxy resin and phenolic resin; and The structural resin is selected from at least one of polymers whose main chain contains aromatic rings and / or heterocycles and rubber-like polymers; The dielectric constant of the inorganic filler is not less than 2000 in the frequency range of 1 kHz to 1 GHz, and 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 high elongation dielectric composition as claimed in claim 1, characterized in that, The polymer whose main chain comprises an aromatic ring and / or a heterocycle is selected from at least one of polyimide, poly(p-phenylenebenzodioxazole), polybenzimidazole, benzoxazine, bismaleimide, and bismaleimide triazine.

3. The high elongation dielectric composition as described in claim 2, characterized in that, The benzoxazine is selected from at least one of bisphenol A type benzoxazine, bisphenol F type benzoxazine, MDA type benzoxazine, DCPD type benzoxazine, phenol type benzoxazine and DOPO type benzoxazine.

4. The high elongation dielectric composition as described in claim 2, characterized in that, The polyimide is selected from at least one of liquid polyimide and thermoplastic polyimide.

5. The high elongation dielectric composition as described in claim 2, characterized in that, The bismaleimide is selected from at least one of diaminodiphenylmethane modified bismaleimide, biphenyl-containing bismaleimide, high-performance thermoplastic resin blended toughened modified bismaleimide, isopropyl-p-phenyl bismaleimide, PI modified bismaleimide, and cyanate ester modified bismaleimide.

6. The dielectric composition with high elongation as described in any one of claims 1 to 5, characterized in that, The glass transition temperature of the polymer whose main chain comprises aromatic rings and / or heterocycles is not lower than 130°C.

7. The high elongation dielectric composition as described in claim 2, characterized in that, The rubber polymer is selected from at least one of natural rubber, nitrile rubber, styrene-butadiene rubber, chloroprene rubber, ethylene propylene diene monomer (EPDM) rubber, modified EPDM rubber, thermoplastic EPDM rubber, acrylic rubber, fluororubber, EPDM rubber, polyurethane rubber, and silicone rubber.

8. The high elongation dielectric composition as claimed in claim 1, characterized in that, The epoxy resin is selected from at least one of glycidylamine epoxy resin, phenoxy resin, polyfunctional o-cresol glycidyl ether epoxy resin, phenol-biphenyl epoxy resin, bisphenol F solid epoxy resin, isocyanate modified epoxy resin, naphthol type epoxy resin, phenol-formaldehyde epoxy resin, 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 high elongation dielectric composition as claimed in claim 1, characterized in that, The phenolic resin is selected from at least one of linear phenol-formaldehyde resin and linear BPA-formaldehyde resin.

10. The high elongation dielectric composition according to claim 1, 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.

11. The high elongation dielectric composition as claimed in claim 1, characterized in that, The inorganic filler is selected from at least one of barium titanate, strontium titanate, and materials with a perovskite-like structure.

12. The high elongation dielectric composition as claimed in claim 11, characterized in that, In the perovskite-like material, the divalent cation may be replaced by at least one selected from monovalent and trivalent cations, and the tetravalent cation may be replaced by at least one selected from trivalent and pentavalent cations.

13. The high elongation dielectric composition as claimed in claim 1, characterized in that, The high elongation dielectric composition comprises, by weight percentage: 15% to 50% of the aforementioned polymeric resin; and 50% to 85% of the inorganic filler.

14. The high elongation dielectric composition as claimed in claim 13, characterized in that, The polymer resin contains, by weight percentage: 70% to 100% of the structural resin; and 0% to 30% of the adhesive resin.

15. The high elongation dielectric composition as claimed in claim 1, characterized in that, The high elongation dielectric composition further comprises 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.

16. The high elongation dielectric composition as claimed in claim 15, characterized in that, The high elongation dielectric composition further comprises an additive, which includes at least one of a leveling agent, a dispersant, and a defoamer.

17. The high elongation dielectric composition as claimed in claim 16, characterized in that, The solvent content is 0.5 to 10 times the total weight of the polymer resin; and / or The content of the additive is 0.5% to 5% by weight of the total weight of the polymer resin.

18. A method for preparing a high elongation dielectric composition, used to prepare the high elongation dielectric composition according to any one of claims 1 to 17, characterized in that, The preparation method includes the following steps: Preparation of resin slurry: The polymer resin is 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 under stirring and mixed to obtain a dielectric composition ink with high elongation.

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

20. The method for preparing the high elongation dielectric composition according to claim 19, characterized in that, The total content of the first solvent and the second solvent is 0.5 to 10 times the total weight of the polymer resin; and / or The total content of the additives is 0.5% to 5% by weight of the total weight of the polymer resin.

21. The method for preparing the high elongation dielectric composition according to claim 18, characterized in that, The conditions for mixing include at least one of the following: The mixing speed during the preparation of the resin slurry is 3600 rpm to 7200 rpm, the slurry temperature is not higher than 45°C, and the duration is between 10 minutes and 60 minutes. The mixing speed during the preparation of the filler slurry is 3600 rpm to 7200 rpm, the slurry temperature is not higher than 45°C, and the duration is between 10 minutes and 60 minutes; and The mixing speed when mixing the filler slurry and the resin slurry is 3600 rpm to 7200 rpm, the slurry temperature is not higher than 45°C, and the duration is between 60 minutes and 120 minutes.

22. The method for preparing the high elongation dielectric composition according to any one of claims 18 to 21, characterized in that, Following the mixing step, the preparation method further includes: Preparation of dry film: The high elongation dielectric composition ink is coated onto the substrate film and cured to obtain a high elongation dielectric composition dry film.

23. The method for preparing the composite dielectric sheet fabric as described in claim 22, characterized in that, The curing process includes: The high elongation dielectric composition ink is dried in a temperature range of 50°C to 120°C for 3 to 30 minutes.

24. A method for applying a composite dielectric sheet fabric, characterized in that, Includes the following steps: Provide the target carrier; Application of the composition: applying the high elongation dielectric composition as described in any one of claims 1 to 17 to the surface of the target carrier; and Curing: The high elongation dielectric composition applied to the target carrier is cured to form a dielectric layer on the surface of the target carrier.

25. The method of applying the composite dielectric sheet fabric as described in claim 24, characterized in that, The curing process includes heating continuously for 15 minutes to 5 hours within a temperature range of 120°C to 220°C.

26. The method of applying the composite dielectric sheet fabric as described in claim 24 or 25, characterized in that, When using a high-elongation dielectric composition in ink form, the step of applying the composition includes: Coating: Applying a high-elongation dielectric composition ink to the surface of the target carrier by means of dip coating, screen printing, pad printing, stencil printing, spraying, or doctor blade printing; and Solvent removal: Dry the high elongation dielectric composition ink coated on the surface of the target carrier at a temperature range of 50°C to 120°C and maintain for 3 to 30 minutes to form the dielectric layer.

27. The method of applying the composite dielectric sheet fabric as described in claim 24 or 25, characterized in that, When a high-elongation dielectric composition in dry film form is used, the step of applying the composition includes: Bonding: A high elongation dielectric composition dry film is hot-pressed onto the surface of the target carrier at a temperature range of 70°C to 150°C and a pressure of not less than 0.4 MPa for 30 seconds to 5 minutes to form the dielectric layer.

28. The method of applying the composite dielectric sheet fabric as described in claim 27, characterized in that, The bonding is performed under a vacuum of less than 0.1 MPa.

29. The method of applying the composite dielectric sheet fabric as described in claim 24, characterized in that, The target carrier is selected from one of polyester film, polyimide film, copper foil, FR4 substrate and silicon wafer.

30. A substrate, characterized in that, include: substrate body; as well as A dielectric layer disposed on the surface of the substrate body, the dielectric layer being formed by curing a high elongation dielectric composition as described in any one of claims 1 to 17.

Images