Halogen-free flame-retardant resin composition, prepreg, laminated board and printed circuit board

Abstract

The invention provides a halogen-free flame-retardant resin composition, a prepreg, a laminated board and a printed circuit board. The halogen-free flame-retardant resin composition comprises 100 parts of thermosetting resin and 10-50 parts of a Di-DOPO flame retardant treated by a silane aid. According to the halogen-free flame-retardant resin composition, the Di-DOPO flame retardant treated by the silane additive is used in the halogen-free flame-retardant resin composition, so that the flame retardant property can be ensured, the effect of improving the heat resistance of the laminated board can be achieved, and the ionic migration resistance and environmental reliability of the laminated board and a circuit board are improved.

Description

Technical Field

[0001] This invention belongs to the field of laminate technology and relates to a halogen-free flame-retardant resin composition, prepreg, laminate, and printed circuit board. Background Technology

[0002] With the advent of the 5G era, data switches, routers, and high-end servers are facing increasingly higher demands for data volume and transmission speed, as well as for the dielectric performance of circuit boards. Di-DOPO, due to its symmetrical structure and stable performance, has become a major halogen-free flame retardant in ultra-low dielectric loss dielectric materials. Furthermore, with the increasing demand for halogen-free and environmentally friendly products, the use of Di-DOPO flame retardants is increasing year by year. However, Di-DOPO itself has a relatively loose solid particle structure and contains many fine particles with a diameter of less than 1μm. This thickens the viscosity of the resin composition, resulting in poor resin flowability, poor wetting of fiberglass cloth, and the easy formation of internal voids during hot pressing, leading to easy moisture absorption by the laminate substrate.

[0003] CN108368396B discloses a polyphenylene ether resin composition comprising poly(arylene ether) and elastomer, bromine- or phosphorus-containing aromatic compounds and inorganic fillers. Although the invention discloses the surface treatment of inorganic fillers with aminosilanes, it cannot improve the problem of easy moisture absorption of the board and cannot improve the board's resistance to damp heat.

[0004] Therefore, in this field, there is a desire to develop a material that can improve the resistance of the sheet material to damp heat and has excellent dielectric properties. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a halogen-free flame retardant resin composition, prepreg, laminate, and printed circuit board.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] On one hand, the present invention provides a halogen-free flame retardant resin composition comprising 100 parts of thermosetting resin and 10-50 parts of Di-DOPO flame retardant treated with silane additives.

[0008] In this invention, by using Di-DOPO flame retardant treated with silane additives in the halogen-free flame retardant resin composition, not only can the flame retardant performance be guaranteed, but it can also improve the heat resistance of the laminate, thereby enhancing the resistance to ion migration and environmental reliability of the laminate and circuit board.

[0009] In the halogen-free flame retardant resin composition of the present invention, the amount of Di-DOPO flame retardant treated with silane additives can be 10 parts by weight, 15 parts by weight, 18 parts by weight, 20 parts by weight, 25 parts by weight, 30 parts by weight, 35 parts by weight, 40 parts by weight, 45 parts by weight, or 50 parts by weight.

[0010] In this invention, the structural formula of the Di-DOPO flame retardant is as follows:

[0011] .

[0012] Preferably, the silane auxiliaries are selected from any one or a combination of at least two of N-phenyl-3-aminopropyltrimethoxysilane, methacryloyloxypropylmethyldiethoxysilane, methacryloyloxypropyltriethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropylmethyldiethoxysilane, methyltrimethoxysilane, dimethoxydiphenylsilane, dimethoxysilane, hexamethyldisilazane, or hexamethylethoxysilane.

[0013] Preferably, the Di-DOPO flame retardant treated with the silane additive is a mixture obtained by directly mixing the Di-DOPO flame retardant and the silane additive and drying it. The silane additive is selected from any one or a combination of at least two of N-phenyl-3-aminopropyltrimethoxysilane (e.g., Shin-Etsu KBM-573), methacryloyloxypropylmethyldiethoxysilane (e.g., Shin-Etsu KBE-502), methacryloyloxypropyltriethoxysilane (e.g., Shin-Etsu KBE-503), γ-methacryloyloxypropyltrimethoxysilane (e.g., Shin-Etsu KBM-503), 3-methacryloyloxypropylmethyldiethoxysilane (e.g., Shin-Etsu KBM-502), methyltrimethoxysilane (e.g., Shin-Etsu KBM-13), dimethoxydiphenylsilane (e.g., Shin-Etsu KBM-202SS), or dimethoxysilane (e.g., Shin-Etsu KBM-3103C).

[0014] In this invention, the method for directly mixing the silane additive with the Di-DOPO flame retardant is as follows: the silane additive is dissolved in a solvent (e.g., ethanol, methanol, n-butanol, or isopropanol) and mixed with the Di-DOPO flame retardant, stirred for 1-4 h (e.g., 1 h, 1.4 h, 1.8 h, 2.2 h, 2.6 h, 3 h, 3.4 h, 3.8 h, or 4 h, etc.), and dried at 80-150℃ (e.g., 100℃, 110℃, 120℃, 130℃, 140℃, or 150℃) for 1-8 h (e.g., 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h, 6 h, 6.5 h, 7 h, 7.5 h, or 8 h, etc.).

[0015] Preferably, the Di-DOPO flame retardant treated with the silane additive is obtained by hydrolyzing the silane additive, then mixing the hydrolysis product with the Di-DOPO flame retardant and drying it; the silane additive is hexamethyldisilazane (e.g., Shin-Etsu SZ-31), N-phenyl-3-aminopropyltrimethoxysilane (e.g., Shin-Etsu KBM-573), methacryloyloxypropylmethyldiethoxysilane (e.g., Shin-Etsu KBE-502), or methacryloyloxypropyltriethoxysilane (e.g., Shin-Etsu KBE-503). The following are all of the following: γ-methacryloxypropyltrimethoxysilane (e.g., Shin-Etsu KBM-503), 3-methacryloxypropylmethyldimethoxysilane (e.g., Shin-Etsu KBM-502), methyltrimethoxysilane (e.g., Shin-Etsu KBM-13), dimethoxydiphenylsilane (e.g., Shin-Etsu KBM-202SS), dimethoxysilane (e.g., Shin-Etsu KBM-3103C), or hexamethylethoxysilane (e.g., Shin-Etsu KBE-3063).

[0016] In this invention, the drying can be oven drying, and the drying conditions are 80-150℃ (e.g., 100℃, 110℃, 120℃, 130℃, 140℃ or 150℃).

[0017] In this invention, hexamethyldisilazane cannot be directly added to the resin composition after being mixed with Di-DOPO. It must be mixed with the hydrolyzed hexamethyldisilazane and Di-DOPO flame retardant and dried before it can be used.

[0018] In this invention, the method for hydrolyzing the silane additive is as follows: the silane additive is dissolved in a solvent (e.g., water, ethanol, methanol, n-butanol or isopropanol) and mixed with an aqueous solution of acetic acid or phosphoric acid with a concentration of 0.1-3%, which causes hydrolysis.

[0019] Preferably, the hydrolysis product is mixed with Di-DOPO flame retardant, stirred for 1-4 h (e.g., 1 h, 2 h, 3 h or 4 h), and then dried at 100-150℃ (e.g., 100℃, 110℃, 120℃, 130℃, 140℃ or 150℃) to obtain Di-DOPO flame retardant treated with silane additive.

[0020] Preferably, the silane additive in the Di-DOPO flame retardant treated with silane additive accounts for 0.2-2% by mass, for example, 0.2%, 0.5%, 0.8%, 1.1%, 1.4%, 1.7%, 1.9% or 2%, etc.

[0021] Thermosetting resin compositions are composed of components that can undergo self-polymerization or cross-linking reactions with other components when heated to form thermosetting resins.

[0022] In this invention, the thermosetting resin is selected from any one or a combination of at least two of the following: polyphenylene ether, bismaleimide and its derivatives, benzocyclobutene-containing oligomers, alkynyl compounds, triallyl isocyanurate, triallyl cyanurate, silicone resins, aromatic compounds containing two or more double bonds, or olefin copolymers.

[0023] Preferably, the olefin copolymer is selected from any one or at least two of the copolymers formed by butadiene, styrene, divinylbenzene, maleic anhydride, benzocyclobutene, norbornene, or compounds having two or more olefin groups and butadiene.

[0024] Preferably, the halogen-free flame-retardant resin composition further includes inorganic fillers.

[0025] Preferably, the inorganic packing includes any one or a combination of at least two of spherical packing, angular packing, or sheet packing.

[0026] Preferably, the inorganic packing contains ≥10% by mass of spherical packing, such as 10%, 20%, 30%, 40%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, etc.

[0027] Preferably, the inorganic filler comprises any one or a combination of at least two of the following: silica, silica powder, alumina, titanium dioxide, mica, silica, barium titanate, potassium titanate, strontium titanate, calcium titanate, aluminum carbonate, magnesium hydroxide, aluminum hydroxide, aluminum silicate, calcium carbonate, calcium silicate, magnesium silicate, silicon nitride, boron nitride, clay, talc, aluminum borate, silicon carbide, or beryllium oxide.

[0028] Preferably, the inorganic filler contains ≥30% silica by mass, for example, 30%, 40%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, etc.

[0029] Preferably, the content of inorganic filler in the halogen-free flame retardant resin composition is 20-150 parts by weight (e.g., 20 parts by weight, 36 parts by weight, 52 parts by weight, 68 parts by weight, 84 parts by weight, 100 parts by weight, 116 parts by weight, 132 parts by weight or 150 parts by weight, etc.), preferably 25-80 parts by weight.

[0030] Preferably, the halogen-free flame retardant resin composition further includes an initiator.

[0031] Preferably, the initiator is selected from any one or a combination of at least two of the following: peroxide initiator, metal salt of acetylacetone, metal salt of naphthenic acid, vanadium pentoxide, amine compound (e.g., aniline), quaternary ammonium salt, imidazole, or triphenylphosphine.

[0032] Preferably, the peroxide initiator is selected from any one or a combination of at least two of the following: dicumyl peroxide, tert-butyl peroxide, di-tert-butyl peroxide, tert-butyl peroxyisopropyl carbonate, 2,5-dimethyl-2,5-di-tert-butylcumyl peroxyhexyn-3, 2,5-dimethyl-2,5-di-tert-butyl peroxide, p-menthol peroxide, 1,1-bis(tert-amylperoxy)cyclohexane, diisopropylbenzene hydrogen peroxide, benzoyl peroxide, or benzoyl peroxide.

[0033] The peroxide initiator has a decomposition temperature that matches the processing temperature. Initiators with a half-life of 1 hour at temperatures between 110°C and 230°C (e.g., 110°C, 135°C, 160°C, 185°C, or 230°C) are preferred. Initiators with a half-life of 1 hour at temperatures between 110°C and 170°C are even more preferred.

[0034] Preferably, the initiator content in the halogen-free flame retardant resin composition is 0.1-2 parts by weight (e.g., 0.1 parts by weight, 0.3 parts by weight, 0.5 parts by weight, 0.7 parts by weight, 0.9 parts by weight, 1.1 parts by weight, 1.3 parts by weight, 1.5 parts by weight, 1.7 parts by weight, or 2 parts by weight, etc.), preferably 0.15-1 parts by weight.

[0035] To better ensure the flame retardant properties of the resin composition, preferably, the halogen-free flame retardant resin composition may also include other flame retardants, which are selected from any one or a combination of at least two of nitrogen-containing phosphate flame retardants, phosphazene flame retardants, or 2,6-bis(2,6-dimethylphenyl)phosphonobenzene.

[0036] Preferably, the nitrogen-containing phosphate flame retardant is selected from any one or a combination of at least two of melamine phosphate, melamine polyphosphate, or dimelamine pyrophosphate.

[0037] Preferably, the phosphazene flame retardant is selected from any one or at least a combination of two of hexachlorocyclotriphosphazene, alkoxycyclotriphosphazene, phenoxycyclotriphosphazene, hexaaminocyclotriphosphazene, or aryloxy-substituted polyphosphazene.

[0038] The study found that when nitrogen-containing flame retardants are combined with the Di-DOPO flame retardant described in this invention, the flame retardant effect is better and the burning time is shorter.

[0039] Preferably, the amount of the other flame retardant is 10-40 parts, such as 10 parts, 13 parts, 16 parts, 19 parts, 22 parts, 25 parts, 28 parts, 30 parts, 33 parts, 35 parts, 38 parts or 40 parts, etc.

[0040] Preferably, the halogen-free flame-retardant resin composition further includes a silane coupling agent, added in an amount of 0.1-3 parts by weight. Studies have found that directly adding a certain amount of silane coupling agent to the halogen-free resin composition of the present invention can improve the toughness of the resin composition and enhance the bonding strength between the resin composition and fiberglass reinforcement materials, copper foil, etc.

[0041] On the other hand, the present invention provides a resin adhesive obtained by dissolving or dispersing the halogen-free flame-retardant resin composition as described above in a solvent.

[0042] On the other hand, the present invention provides a prepreg comprising a reinforcing material and a halogen-free flame-retardant resin composition as described above, which is attached to the reinforcing material after impregnation and drying.

[0043] The reinforcing material includes any one or a combination of glass fiber cloth, organic fiber cloth, and glass fiber nonwoven fabric.

[0044] Preferably, the proportion of alkali metals in the glass fibers of the glass fiber cloth or glass fiber nonwoven fabric is less than 0.1% (e.g., 0.09%, 0.08%, 0.06%, 0.04%, 0.02%, etc.), and the proportion of Ca element is less than 10% (e.g., 8%, 6%, 4%, 2%, 1%, etc.). This results in a laminate with superior dielectric properties.

[0045] Preferably, the organic fibers used in the organic fiber cloth have a glass transition temperature greater than 200°C, such as 220°C, 250°C, 300°C, 350°C, 400°C, etc.

[0046] On the other hand, the present invention provides a laminate comprising at least one prepreg as described above.

[0047] On the other hand, the present invention provides a metal foil laminate, the metal foil laminate comprising at least one prepreg as described above and metal foils covering both sides of the laminated prepreg.

[0048] On the other hand, the present invention provides a printed circuit board, the printed circuit board comprising the prepreg as described above, or the laminate as described above, or the metal foil laminate as described above.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] This invention utilizes Di-DOPO flame retardant treated with silane additives in a halogen-free flame retardant resin composition, which not only ensures flame retardant performance but also improves the heat resistance of the laminate, thereby enhancing the resistance to ion migration and environmental reliability of the laminate and circuit board. Detailed Implementation

[0051] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0052] Preparation Example 1

[0053] 10g of N-phenyl-3-aminopropyltrimethoxysilane (KBM-573, Shin-Etsu Chemical, Japan) and 100g of butanone were mixed evenly, and then 1000g of Di-DOPO flame retardant (XP7866, Albemarle, USA) was added and stirred for 2 hours. The mixture was then dried at 140℃ for 4 hours to obtain Di-DOPO flame retardant P1 treated with silane additives.

[0054] Preparation Example 2

[0055] 10g of dimethoxydiphenylsilane (KBM-202SS, Shin-Etsu Chemical, Japan) and 100g of butanone were mixed evenly, and then 1000g of Di-DOPO flame retardant (XP7866, Albemarle, USA) was added and stirred for 2 hours. The mixture was then dried at 100℃ for 4 hours to obtain Di-DOPO flame retardant P2 treated with silane additives.

[0056] Preparation Example 3

[0057] 10g of N-phenyl-3-aminopropyltrimethoxysilane (KBM-573, Shin-Etsu Chemical, Japan) and 40g of methanol were mixed evenly, and 200g of a 0.5% aqueous solution of acetic acid was added. The mixture was stirred for 20 minutes, and then 1000g of Di-DOPO flame retardant (XP7866, Albemarle, USA) was added and stirred for 2 hours. After filtration, the mixture was dried at 120℃ for 4 hours to obtain Di-DOPO flame retardant P3 treated with silane additives.

[0058] Preparation Example 4

[0059] 10g of hexamethyldisilazane (SZ-31, Shin-Etsu Chemical, Japan) and 40g of methanol were mixed evenly, and 200g of a 0.5% phosphoric acid aqueous solution was added. The mixture was stirred for 20 minutes, and then 1000g of Di-DOPO flame retardant (XP7866, Albemarle, USA) was added. The mixture was stirred for 4 hours. After filtration, the mixture was dried at 140℃ for 4 hours to obtain Di-DOPO flame retardant P4 treated with silane additives.

[0060] Preparation Example 5

[0061] 10g of hexamethyldisilazane (SZ-31, Shin-Etsu Chemical, Japan) and 40g of methanol were mixed evenly and stirred for 20 minutes. Then, 1000g of Di-DOPO flame retardant (XP7866, Albemarle, USA) was added and stirred for 4 hours. After filtration, the mixture was dried at 140℃ for 4 hours to obtain Di-DOPO flame retardant P5 after treatment with silane additives.

[0062] Preparation of Comparative Example 1

[0063] 10g of hexamethyldisilazane (SZ-31, Shin-Etsu Chemical, Japan) and 40g of methanol were mixed evenly, and 200g of a 0.5% phosphoric acid aqueous solution was added. The mixture was stirred for 20 minutes, and then 1000g of DQ1028L (spherical silica powder, Lianrui Chemical, Jiangsu Province) filler was added and stirred for 4 hours. After filtration, the mixture was dried at 140℃ for 4 hours to obtain filler F1 treated with silane additives.

[0064] Preparation of Comparative Example 2

[0065] 10g of N-phenyl-3-aminopropyltrimethoxysilane (KBM-573, Shin-Etsu Chemical, Japan) and 100g of butanone were mixed evenly, and then 1000g of DQ1028L (spherical silica powder, Lianrui Chemical, Jiangsu Province) filler was added and stirred for 2 hours. After filtration, the mixture was dried at 140℃ for 4 hours to obtain filler F2 treated with silane additives.

[0066] The source information of the raw materials used in the examples and comparative examples is as follows:

[0067] XP7866: Di-DOPO flame retardant, Albemarle (USA)

[0068] SA9000: Functionalized polyphenylene ether, SABIC;

[0069] Ricon100: A copolymer of butadiene and styrene, Clayville;

[0070] B-3000: Polybutadiene resin, Nippon Soda;

[0071] Ricon257: A copolymer of butadiene, divinylbenzene and styrene, Clayville;

[0072] DX408: Mn approximately 74,000, butadiene-styrene copolymer, Kraton;

[0073] TAIC: Triallyl isocyanurate, Evonik;

[0074] DVB: Divinylbenzene, Nippon Steel;

[0075] DQ1028L: Spherical silica powder, no surface treatment, Jiangsu Lianrui;

[0076] Nonfla 601: Melamine polyphosphate, Douben Company;

[0077] Z-6030: Allyl silane coupling agent, Shin-Etsu Chemical Co., Ltd., Japan;

[0078] DCP: Dicumyl peroxide, Nourion;

[0079] Toluene: a solvent, commercially available;

[0080] BMI-70: Bismaleimide resin, KI (Japan);

[0081] MEK: Solvent, commercially available.

[0082] Example:

[0083] The compositions of the halogen-free flame retardant resin compositions provided in Examples 1-8 and Comparative Examples 1-3 are shown in Tables 1 and 2 (where the amount of each component is in parts by weight).

[0084] The components of the halogen-free flame-retardant resin composition were dissolved in a solvent to obtain a resin solution with a solid content of 68%.

[0085] A low-Dk glass fiber cloth of model 2116 is uniformly impregnated with the above-mentioned resin solution and baked in a forced-air oven at 155°C for 3 minutes to obtain a prepreg sheet (i.e., prepreg material). Four of the above-mentioned prepreg sheets are overlapped, covered with 35m copper foil on the top and bottom, and pressed in a vacuum hot press at 3MPa pressure and 210°C for 90 minutes to obtain a laminate.

[0086] Performance testing of the laminate:

[0087] (1) Adhesive viscosity: according to the test requirements of GB / T1723 Zhongtu-4 viscometer.

[0088] (2) Solder immersion delamination time (min): Immerse the sample board (size 50mmX50mm) in solder at 288℃ and record the time when the sample board delamination or blistering occurs.

[0089] (3) High temperature and high humidity immersion test after 24 hours: The sample board (50mm x 50mm) after etching copper foil was placed in a constant temperature and humidity chamber at 85℃ and 85% humidity for 24 hours, and then immersed in 288℃ solder for 10 seconds each time, for a total of 10 immersions, to see if delamination and board explosion would occur. The sample board needs to be cooled to room temperature before each immersion.

[0090] (4) Anti-CAF: The anti-CAF capability of the inter-hole insulation material was evaluated according to IPC-TM-650 2.6.25. The test sample consisted of two rows of parallel through holes, 10 holes per row, with a hole diameter of 0.4 mm and a minimum wall spacing of 0.250 mm between adjacent holes. The test was conducted in a constant temperature and humidity chamber with conditions set at 80℃±2℃ and 80%±3% relative humidity. During the test, a constant bias voltage of 100 V DC was applied between the two rows of holes for 500 hours. The results were determined by real-time monitoring of the inter-hole insulation resistance. If the inter-hole insulation resistance of all tested holes remained above 100 MΩ throughout the entire 500-hour test period, it was considered 'pass'; if the inter-hole insulation resistance dropped to 100 MΩ or below, it was considered 'fail'.

[0091] The test results are detailed in Tables 1 and 2.

[0092] Table 1

[0093]

[0094] Table 2

[0095]

[0096] Based on the data in Tables 1 and 2, the performance of the board materials in the examples met expectations. Furthermore, after high-temperature and high-humidity treatment, the board samples did not exhibit delamination or board bursting during tin-immersion treatment, and all passed the CAF test. Comparative Example 1 used Di-DOPO flame retardant without silane additive treatment; the adhesive viscosity was high, causing sticking to the cup and resulting in delamination and CAF failure during tin-immersion. Comparative Examples 2 and 3 used fillers treated with silane additives; the adhesive viscosity was relatively lower than that of Comparative Example 1, but still higher than the examples, and delamination also occurred, leading to failure in the CAF test.

[0097] The applicant declares that the present invention is illustrated through the above embodiments to demonstrate the halogen-free flame-retardant resin composition, prepreg, laminate, and printed circuit board of the present invention. However, the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the products of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A halogen-free flame-retardant resin composition, characterized in that, The halogen-free flame-retardant resin composition comprises 100 parts of thermosetting resin and 10-50 parts of Di-DOPO flame retardant treated with silane additives.

2. The halogen-free flame-retardant resin composition according to claim 1, characterized in that, The structural formula of the Di-DOPO flame retardant is shown below: 。 3. The halogen-free flame-retardant resin composition according to claim 1 or 2, characterized in that, The silane auxiliaries are selected from any one or a combination of at least two of N-phenyl-3-aminopropyltrimethoxysilane, methacryloyloxypropylmethyldiethoxysilane, methacryloyloxypropyltriethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropylmethyldiethoxysilane, methyltrimethoxysilane, dimethoxydiphenylsilane, dimethoxysilane, hexamethyldisilazane, or hexamethylethoxysilane. Preferably, the Di-DOPO flame retardant treated with the silane additive is a mixture obtained by directly mixing the Di-DOPO flame retardant and the silane additive, wherein the silane additive is selected from any one or a combination of at least two of N-phenyl-3-aminopropyltrimethoxysilane, methacryloyloxypropylmethyldiethoxysilane, methacryloyloxypropyltriethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropylmethyldimethoxysilane, methyltrimethoxysilane, dimethoxydiphenylsilane, or dimethoxysilane; Preferably, the Di-DOPO flame retardant treated with the silane additive is obtained by hydrolyzing the silane additive, then mixing the hydrolysis product with the Di-DOPO flame retardant and drying it; the silane additive is any one or a combination of at least two of hexamethyldisilazane, N-phenyl-3-aminopropyltrimethoxysilane, methacryloyloxypropylmethyldiethoxysilane, methacryloyloxypropyltriethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropylmethyldimethoxysilane, methyltrimethoxysilane, dimethoxydiphenylsilane, dimethoxysilane, or hexamethylethoxysilane; Preferably, the silane additive in the Di-DOPO flame retardant treated with silane additives accounts for 0.2-2% by mass.

4. The halogen-free flame-retardant resin composition according to any one of claims 1-3, characterized in that, The thermosetting resin is selected from any one or a combination of at least two of the following: polyphenylene ether, bismaleimide compounds, benzocyclobutene-containing oligomers, alkynyl compounds, triallyl isocyanurate, triallyl cyanurate, silicone resins, or olefin polymers. Preferably, the olefin polymer is selected from one or a combination of at least two of butadiene, styrene, divinylbenzene, monovinyl aromatic compounds, maleic anhydride, benzocyclobutene, norbornene, or compounds having two or more olefin groups.

5. The halogen-free flame-retardant resin composition according to any one of claims 1-4, characterized in that, The halogen-free flame-retardant resin composition also includes inorganic fillers; Preferably, the amount of inorganic filler in the halogen-free flame retardant resin composition is 20 to 150 parts, more preferably 25 to 80 parts; Preferably, the inorganic packing includes any one or a combination of at least two of spherical packing, angular packing, or sheet packing; Preferably, the inorganic packing contains ≥10% by mass of spherical packing. Preferably, the inorganic filler comprises any one or a combination of at least two of the following: silica, silica powder, alumina, titanium dioxide, mica, silica, barium titanate, potassium titanate, strontium titanate, calcium titanate, aluminum carbonate, magnesium hydroxide, aluminum hydroxide, aluminum silicate, calcium carbonate, calcium silicate, magnesium silicate, silicon nitride, boron nitride, clay, talc, aluminum borate, silicon carbide, or beryllium oxide. Preferably, the inorganic filler contains ≥30% silica by mass. Preferably, the halogen-free flame retardant resin composition further includes an initiator; Preferably, the initiator content in the halogen-free flame retardant resin composition is 0.1 to 2 parts, more preferably 0.15 to 1 part; Preferably, the initiator is selected from any one or a combination of at least two of the following: peroxide initiator, metal salt of acetylacetone, metal salt of naphthenic acid, vanadium pentoxide, amine compound, quaternary ammonium salt, imidazole or triphenylphosphine; Preferably, the peroxide initiator is selected from any one or a combination of at least two of the following: dicumyl peroxide, tert-butyl peroxide, di-tert-butyl peroxide, tert-butyl peroxyisopropyl carbonate, 2,5-dimethyl-2,5-di-tert-butylcumyl peroxyhexyn-3, 2,5-dimethyl-2,5-di-tert-butyl peroxide, p-menthol peroxide, 1,1-bis(tert-amylperoxy)cyclohexane, diisopropylbenzene hydrogen peroxide, benzoyl peroxide, or benzoyl peroxide. Preferably, the halogen-free flame-retardant resin composition may further include other flame retardants, which are selected from any one or a combination of at least two of nitrogen-containing phosphate flame retardants, phosphazene flame retardants, or 2,6-bis(2,6-dimethylphenyl)phosphonobenzene. Preferably, the nitrogen-containing phosphate flame retardant is selected from any one or a combination of at least two of melamine phosphate, melamine polyphosphate, or dimelamine pyrophosphate; Preferably, the phosphazene flame retardant is selected from any one or at least a combination of two of hexachlorocyclotriphosphazene, alkoxycyclotriphosphazene, phenoxycyclotriphosphazene, hexaaminocyclotriphosphazene, or aryloxy-substituted polyphosphazene. Preferably, the amount of the other flame retardant is 10 to 40 parts.

6. A resin adhesive, characterized in that, The resin solution is obtained by dissolving or dispersing the halogen-free flame-retardant resin composition as described in any one of claims 1-5 in a solvent.

7. A prepreg, characterized in that, The prepreg includes a reinforcing material and a halogen-free flame-retardant resin composition as described in any one of claims 1-5, which is attached to the reinforcing material after impregnation and drying.

8. A laminate, characterized in that, The laminate comprises at least one sheet of prepreg as described in claim 7.

9. A metal foil-coated laminate, characterized in that, The metal foil laminate includes at least one prepreg as described in claim 7 and metal foils covering both sides of the laminated prepreg.

10. A printed circuit board, characterized in that, The printed circuit board includes the prepreg as described in claim 7, the laminate as described in claim 8, or the metal foil-coated laminate as described in claim 9.

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