A bonded sheet, a method for producing the same, and use thereof

Abstract

The present application provides a kind of bonding sheet and its preparation method and application, the bonding sheet includes reinforcing material, and the resin composition attached to the reinforcing material by twice impregnation drying;The resin composition includes the first resin composition attached after the first impregnation drying and the second resin composition attached after the second impregnation drying;The first resin composition includes the combination of phenolic resin, nitrogen-containing flame retardant and phosphorus-containing flame retardant;The second resin composition includes the combination of epoxy resin, curing agent, halogen-based flame retardant, antimony-based flame retardant and phosphorus-nitrogen flame retardant.The design of first resin composition, second resin composition and its compounding synergy make the bonding sheet have excellent flame retardancy, heat resistance and processability, the metal foil laminated board containing it has excellent flame retardancy, heat resistance and punching property, with significantly improved comprehensive performance.

Description

Technical Field

[0001] This invention belongs to the field of copper clad laminate technology, specifically relating to an adhesive sheet, its preparation method, and its application. Background Technology

[0002] CEM-1 copper-clad laminate uses electronic-grade fiberglass cloth and bleached wood pulp paper as reinforcing materials. These are impregnated with a resin composition specifically for copper-clad laminates, creating a face material reinforced with electronic-grade fiberglass cloth and a core material reinforced with bleached wood pulp paper. Copper foil is then laminated onto the face material and hot-pressed. CEM-1 copper-clad laminate outperforms paper-based copper-clad laminates and is less expensive than fiberglass cloth-based copper-clad laminates, exhibiting strong competitiveness in mechanical properties, electrical properties, cost, and processability. In recent years, with the development of lead-free and functionally integrated end products, the corresponding circuits have become more complex, placing higher demands on the heat resistance, flame retardancy, and perforation properties of CEM-1 copper-clad laminates.

[0003] CN111806001A discloses a method for preparing CEM-1 copper clad laminate, the steps of which are as follows: (1) preparing surface material semi-cured film adhesive; (2) preparing inner material first impregnation resin adhesive: mixing 5-10 parts by weight of phosphorus-containing flame retardant, 1-10 parts by weight of low molecular weight thermosetting resin and 80-90 parts by weight of solvent evenly; (3) preparing inner material second impregnation resin adhesive: mixing 20-35 parts by weight of low molecular weight phosphorus-containing epoxy, 5-15 parts by weight of low molecular weight ordinary epoxy, and 10-20 parts by weight of solvent evenly. 1-5 parts by weight of nitrogen-containing phenolic resin, 10-20 parts by weight of modified phenolic resin, 1-10 parts by weight of flame-retardant filler, 20-30 parts by weight of inner filler, and 20-30 parts by weight of solvent are mixed evenly; (4) Electronic grade fiberglass cloth is impregnated in the adhesive solution prepared in step (1), dried, and a surface material semi-cured sheet is obtained; wet-strength wood pulp paper is impregnated in the adhesive solution prepared in step (2), dried, and an inner material semi-cured sheet is obtained; the inner material semi-cured sheet and the surface material semi-cured sheet are stacked and covered with copper foil and hot-pressed to obtain CEM-1 copper clad laminate. Because phosphorus-containing flame retardant is added to the resin adhesive solution in the first impregnation of the inner material, and phosphorus-containing epoxy, nitrogen-containing phenolic resin and phosphorus-containing nitrogen-containing flame retardant are added to the resin adhesive solution in the second impregnation of the inner material, the CEM-1 copper clad laminate has FV0 flame retardancy, but the amount of flame retardant added to the board is large, the heat resistance and punching performance are worse, and the immersion soldering resistance at 288℃ is only 24 s-26 s.

[0004] CN111572131A discloses a method for preparing CEM-1 copper clad laminate, including the steps of preparing surface resin, preparing inner resin for one impregnation, preparing inner resin for two impregnations, preparing prepreg, and hot pressing. The surface resin contains one or more of magnesium hydroxide, antimony trioxide, and aluminum hydroxide, and the inner resin for two impregnations contains one or a mixture of magnesium hydroxide and antimony trioxide, giving the laminate good flame retardancy. Simultaneously, the inner resin for two impregnations contains polyvinyl alcohol formaldehyde-polyvinyl alcohol-polyacrylic acid copolymer and cyanate ester modified resin, improving the heat resistance of the laminate. However, its solderability at 288℃ is <70 s, which is still significantly insufficient, and its perforation capability cannot meet the processing requirements of high-performance circuit boards.

[0005] CN109233209A discloses a halogenated antimony-free resin composition, comprising the following components: 25-70 parts by weight of flame-retardant epoxy resin, 10-40 parts by weight of non-flame-retardant epoxy resin, 20-60 parts by weight of composite curing agent, and 0.05-1.0 parts by weight of curing accelerator; wherein the flame-retardant epoxy resin includes a composition of phosphorus-containing epoxy resin, brominated epoxy resin, and nitrogen-containing epoxy resin, which, when combined with the non-flame-retardant epoxy resin, can enhance the flame retardancy, solderability, and heat resistance of CEM-1 copper-clad laminate. However, due to the addition of a large amount of flame-retardant components to the resin system, the perforation properties of the copper-clad laminate deteriorate, and there is also considerable room for improvement in heat resistance.

[0006] Currently, improving the flame retardancy of CEM-1 copper-clad laminates is mainly achieved by adding large amounts of flame retardants. However, large amounts of flame retardants lead to a decrease in the heat resistance and perforation properties of CEM-1 copper-clad laminates, making it difficult to improve their overall performance. Therefore, developing copper-clad laminates with excellent flame retardancy, heat resistance, and perforation processability is a key research focus in this field. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide an adhesive sheet, its preparation method, and its application. Through the design and synergistic compounding of a first resin composition and a second resin composition, the adhesive sheet possesses excellent flame retardancy, heat resistance, and processability. The metal foil laminate containing the adhesive sheet also exhibits excellent flame retardancy, heat resistance, and punching processability, resulting in significantly improved overall performance.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides an adhesive sheet comprising a reinforcing material and a resin composition attached to the reinforcing material by a double impregnation and drying process;

[0010] The resin composition includes a first resin composition that adheres after a first impregnation and drying and a second resin composition that adheres after a second impregnation and drying;

[0011] The first resin composition comprises a combination of phenolic resin, a nitrogen-containing flame retardant, and a phosphorus-containing flame retardant;

[0012] The second resin composition comprises a combination of epoxy resin, curing agent, halogenated flame retardant, antimony-based flame retardant, and phosphorus-nitrogen flame retardant.

[0013] In the adhesive sheet provided by this invention, a resin composition is attached to a reinforcing material through two impregnation and drying processes. The first impregnation and drying process attaches a first resin composition, comprising phenolic resin, a nitrogen-containing flame retardant, and a phosphorus-containing flame retardant, to the reinforcing material. A second impregnation and drying process then attaches a second resin composition. This invention is based on the principle of selecting different flame-retardant systems for CEM-1 copper-clad laminates during different combustion processes. A halogenated antimony flame-retardant system is selected for the first combustion stage, and a phosphorus-nitrogen flame-retardant system is selected for the second combustion stage. These flame-retardant systems work synergistically to achieve highly efficient flame retardancy at different combustion stages, significantly reducing the amount of halogenated antimony flame retardant used. This solves the problem in existing technologies where adding large amounts of flame retardants (e.g., halogenated antimony flame retardants) results in poor heat resistance and perforation properties of CEM-1 copper-clad laminates, hindering overall performance improvement. The resulting adhesive sheet possesses excellent heat resistance, flame retardancy, and processability. The metal foil laminate containing the adhesive sheet not only has excellent flame retardant properties, but also significantly improved heat resistance, punching and processability, resulting in excellent overall performance and fully meeting the application requirements of high-performance circuit boards.

[0014] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The purpose and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0015] Preferably, the phenolic resin is an aqueous phenolic resin, and more preferably a small-molecule water-soluble phenolic resin.

[0016] Preferably, the number average molecular weight of the phenolic resin is 100-2000 g / mol, for example, it can be 200 g / mol, 500 g / mol, 800 g / mol, 1000 g / mol, 1200 g / mol, 1500 g / mol or 1800 g / mol, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0017] Preferably, based on 100 parts by weight of the phenolic resin, the nitrogen-containing flame retardant is 5-10 parts by weight, for example, 5.5 parts, 6 parts, 6.5 parts, 7 parts, 7.5 parts, 8 parts, 8.5 parts, 9 parts or 9.5 parts, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0018] Preferably, the nitrogen-containing flame retardant includes any one or a combination of at least two of vinyl isocyanate, melamine-glyoxal resin, melamine-formaldehyde resin, methylated melamine resin, butylated melamine resin, triisocyanurate-modified melamine resin, and organosilicon-modified melamine resin.

[0019] Preferably, based on 100 parts by weight of the phenolic resin, the phosphorus-containing flame retardant is 10-20 parts by weight, for example, 11, 12, 13, 14, 15, 16, 17, 18 or 19 parts, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0020] Preferably, the phosphorus-containing flame retardant includes a water-based phosphorus-containing flame retardant.

[0021] Preferably, the phosphorus-containing flame retardant includes any one or a combination of at least two of alkoxycyclotriphosphazene, phenoxycyclotriphosphazene, hexa-p-aldehyde phenoxycyclotriphosphazene, hexa(4-DOPO hydroxymethylphenoxy)cyclotriphosphazene, (2-allylphenoxy)pentaphenoxycyclotriphosphazene, and hexa(4-nitrophenoxy)cyclotriphosphazene.

[0022] In this invention, "DOPO" refers to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

[0023] Preferably, the epoxy resin includes any one or a combination of at least two of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and bisphenol S type epoxy resin.

[0024] Preferably, the epoxy equivalent of the epoxy resin is 150-800 g / eq, for example, it can be 180 g / eq, 200 g / eq, 250 g / eq, 300 g / eq, 350 g / eq, 400 g / eq, 450 g / eq, 500 g / eq, 550 g / eq, 600 g / eq, 650 g / eq, 700 g / eq or 750 g / eq, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0025] Preferably, based on 100 parts by weight of the epoxy resin, the curing agent is 20-80 parts by weight, for example, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, 65 parts, 70 parts or 75 parts, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0026] Preferably, the curing agent includes any one or a combination of at least two of vegetable oil-modified phenolic resin, linear phenolic resin, and thermosetting phenolic resin.

[0027] Preferably, based on 100 parts by weight of the epoxy resin, the halogenated flame retardant is 5-15 parts by weight, for example, 6, 7, 8, 9, 10, 11, 12, 13, or 14 parts, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0028] Preferably, the halogenated flame retardant includes a brominated flame retardant.

[0029] Preferably, the halogenated flame retardant includes any one or a combination of at least two of tetrabromobisphenol A, tribromophenol, decabromodiphenyl ethane, and octabromodiphenyl ethane.

[0030] Preferably, based on 100 parts by weight of the epoxy resin, the antimony-based flame retardant is 2-8 parts by weight, for example, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, 5.5 parts, 6 parts, 6.5 parts, 7 parts or 7.5 parts, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0031] Preferably, the antimony-based flame retardant includes any one or a combination of at least two of antimony oxide, antimony halide, and antimonate.

[0032] Preferably, based on 100 parts by weight of the epoxy resin, the mass of the phosphorus-nitrogen flame retardant is 5-10 parts, for example, 5.5 parts, 6 parts, 6.5 parts, 7 parts, 7.5 parts, 8 parts, 8.5 parts, 9 parts or 9.5 parts, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0033] Preferably, the phosphorus-nitrogen flame retardant includes any one or a combination of at least two of ammonium polyphosphate, melamine polyphosphate, and phosphazene compounds.

[0034] Preferably, the second resin composition further includes a curing accelerator.

[0035] Preferably, based on 100 parts by weight of the epoxy resin, the mass of the curing accelerator is ≤1 part, for example, it can be 0, 0.01, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9 parts, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0036] Preferably, the curing accelerator comprises any one or a combination of at least two of tertiary amines, tertiary phosphines, organometallic complexes, imidazole compounds, and quaternary ammonium salts, with imidazole compounds being more preferred.

[0037] Preferably, the imidazole compound includes any one or a combination of at least two of 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-isopropylimidazole, 2-undecylimidazole, 2-dodecylimidazole, 2-heptadecanylimidazole, 1-benzyl-2-methylimidazole, 2-phenyl-4-methylimidazole, and 1-cyanoethyl-2-methylimidazole.

[0038] As a preferred embodiment of the present invention, the first resin composition comprises the following components in parts by weight:

[0039] 100 parts of phenolic resin

[0040] 5-10 parts of nitrogen-containing flame retardant

[0041] 10-20 parts of phosphorus-containing flame retardant;

[0042] The second resin composition comprises, by weight, the following components:

[0043] 100 parts epoxy resin

[0044] 20-80 parts of curing agent

[0045] 5-15 parts of halogenated flame retardant

[0046] 2-8 parts of antimony-based flame retardant

[0047] 5-10 parts of phosphorus-nitrogen flame retardant

[0048] Curing accelerator 0.01-1 part.

[0049] Preferably, the mass ratio of the first resin composition to the second resin composition is 1:(8-12), for example, it can be 1:8.5, 1:9, 1:9.5, 1:10, 1:10.5, 1:11 or 1:11.5, and more preferably 1:10.

[0050] Preferably, the reinforcing material includes at least one of wood pulp paper, cotton pulp paper, or nonwoven fabric, and more preferably wood pulp paper and / or cotton pulp paper.

[0051] Preferably, the resin composition in the adhesive sheet has a mass percentage content of 40%-70%, for example, it can be 42%, 45%, 48%, 50%, 52%, 55%, 58%, 60%, 62%, 65% or 68%, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0052] In a second aspect, the present invention provides a method for preparing an adhesive sheet as described in the first aspect, the method comprising:

[0053] The reinforcing material is first impregnated in the adhesive solution of the first resin composition and then first dried to obtain a prepreg.

[0054] The prepreg is immersed in the adhesive solution of the second resin composition for a second time and then dried for a second time to obtain the adhesive sheet.

[0055] Preferably, the solvent of the liquid resin composition comprises water.

[0056] Preferably, the solid content of the first resin composition is 10%-30%, for example, it can be 12%, 15%, 18%, 20%, 22%, 25% or 28%, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0057] Preferably, the solvent of the adhesive solution of the second resin composition includes any one or a combination of at least two of ketone solvents, aromatic hydrocarbon solvents, and ester solvents, and more preferably ketone solvents and / or aromatic hydrocarbon solvents.

[0058] Preferably, the ketone solvent includes any one or a combination of at least two of acetone, butanone, and cyclohexanone.

[0059] Preferably, the aromatic hydrocarbon solvent includes any one or a combination of at least two of toluene, xylene, and trimethylbenzene.

[0060] Preferably, the ester solvent includes ethyl acetate and / or butyl acetate.

[0061] Preferably, the solid content of the adhesive solution of the second resin composition is 50%-70%, for example, it can be 52%, 55%, 58%, 60%, 62%, 65% or 68%, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0062] Preferably, the first immersion time and the second immersion time are each independently 5-60 s, for example, 6 s, 8 s, 10 s, 15 s, 20 s, 25 s, 30 s, 35 s, 40 s, 45 s, 50 s or 55 s, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific point values ​​included in the range.

[0063] Preferably, the temperatures of the first drying and the second drying are each independently between 100-220°C, for example, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C or 210°C, as well as specific values ​​between the above-mentioned values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0064] Preferably, the drying time for the first drying and the drying time for the second drying are each independently 1-30 min, for example, 2 min, 5 min, 8 min, 10 min, 15 min, 20 min or 25 min, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range, but 1-10 min is further preferred.

[0065] Preferably, the first drying time is 3-5 minutes.

[0066] Preferably, the second drying time is 2-4 minutes.

[0067] Thirdly, the present invention provides a metal foil laminate, the metal foil laminate comprising a metal foil and at least one adhesive sheet as described in the first aspect.

[0068] Preferably, the metal foil includes copper foil, aluminum foil, nickel foil, or SUS foil, and more preferably copper foil.

[0069] Preferably, the metal foil laminate is a CEM-1 copper clad laminate, which includes a laminate and copper foil disposed on one or both sides of the laminate; the laminate includes a face material and a core material, and the core material includes at least one adhesive sheet as described in the first aspect.

[0070] Preferably, the number of adhesive sheets in the core material is 1-20, for example, 2, 3, 5, 6, 8, 10, 12, 15 or 18 sheets.

[0071] For example, the preparation method of the CEM-1 copper clad laminate includes: bonding fabric to both sides of the core material to obtain a laminate; pressing copper foil onto one or both sides of the laminate and curing it to obtain the CEM-1 copper clad laminate.

[0072] Preferably, the curing temperature is 130-190℃, for example 135℃, 140℃, 145℃, 150℃, 155℃, 160℃, 165℃, 170℃, 175℃, 180℃ or 185℃, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0073] Preferably, the curing pressure is 4-8 MPa, for example, it can be 4.5 MPa, 5 MPa, 5.5 MPa, 6 MPa, 6.5 MPa, 7 MPa or 7.5 MPa, as well as specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0074] Preferably, the curing time is 30-300 min, for example, it can be 40 min, 60 min, 80 min, 100 min, 120 min, 140 min, 150 min, 160 min, 180 min, 200 min, 220 min, 240 min, 260 min or 280 min, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0075] Fourthly, the present invention provides a printed circuit board comprising an adhesive sheet as described in the first aspect and / or a metal foil laminate as described in the third aspect.

[0076] Compared with the prior art, the present invention has the following beneficial effects:

[0077] (1) In the adhesive sheet provided by the present invention, through the component design and compounding synergy of the first resin composition and the second resin composition, the adhesive sheet achieves significant improvement in flame retardancy, heat resistance and processability, which solves the problem that the CEM-1 copper clad laminate has poor heat resistance and punching ability due to the addition of a large amount of flame retardant in the prior art. The metal foil laminate containing the adhesive sheet has excellent flame retardancy, as well as significantly improved heat resistance and punching processability, low water absorption and excellent comprehensive performance.

[0078] (2) Through the design and optimization of the first resin composition and the second resin composition in the adhesive sheet, the present invention enables the CEM-1 copper clad laminate containing it to have a flame retardancy of UL-94 V-0, thermal stress (288℃, floating solder) ≥162 s, thermal stress (288℃, immersion solder) ≥108 s, T260 ≥83 min, and a punching performance of 5. It has excellent flame retardancy, heat resistance and punching processability, and low water absorption, which fully meets the application requirements of high-performance circuit boards. Detailed Implementation

[0079] 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.

[0080] In the following specific embodiments of the present invention, the materials involved are as follows:

[0081] (1) Phenolic resin

[0082] Waterborne phenolic resin, SQ-9322, with a number average molecular weight of 300-500 g / mol, was purchased from Jinan Shengquan Group Co., Ltd.

[0083] (2) Nitrogen-containing flame retardants

[0084] B1: Melamine-formaldehyde resin, JX-2533, purchased from Dalian Jinxin Chemical Co., Ltd.

[0085] B2: Vinyl isocyanate, JS-5634, purchased from Hubei Jusheng Technology Co., Ltd.;

[0086] B3: Methyl etherified melamine resin, CYMEL 303LF, purchased from Foshan Weng Kai'er.

[0087] (3) Phosphorus-containing flame retardants

[0088] C1: Phenoxycyclotriphosphazene, SPB-100, purchased from Hubei Yuancheng Saichuang Technology Co., Ltd.;

[0089] C2: Hexa-p-aldehyde phenoxycyclotriphosphazene, TC-130, purchased from Jiangsu Tiancheng Chemical Co., Ltd.;

[0090] C3: Hexa(4-DOPOhydroxymethylphenoxy)cyclotriphosphazene, GC-PNP, purchased from Wuhan Haishan Technology Co., Ltd.

[0091] (4) Epoxy resin

[0092] D1: Biphenyl-type phenolic epoxy resin, GELR134, purchased from Hongchang Electronic Materials Co., Ltd.

[0093] D2: Phenolic linear phenolic epoxy resin, BN-57, purchased from Jinan Kangyu New Materials Co., Ltd.

[0094] D3: o-cresol linear phenolic epoxy resin, LP-39, purchased from Wuhan Jiyesheng Chemical Co., Ltd.

[0095] (5) Curing agent

[0096] Linear phenolic resin, ZP150, purchased from Zhangjiagang Yarui Chemical Co., Ltd.

[0097] (6) Halogenated flame retardants

[0098] F1: Decabromodiphenyl ethane, ZK-500, purchased from Chengdu Jiaye Biotechnology Co., Ltd.;

[0099] F2: Tetrabromobisphenol A, BC-52, purchased from Laizhou Dilong Chemical Co., Ltd.;

[0100] F3: Tribromophenol, ZX-45, purchased from Qianyan Chemical Technology (Wuhan) Co., Ltd.;

[0101] (7) Antimony-based flame retardants

[0102] G1: Antimony pentoxide, SD-405, purchased from Wuhan Xinghe Chemical Co., Ltd.;

[0103] G2: Antimony pentoxide, ZP530, purchased from Zhangjiagang Yarui Chemical Co., Ltd.;

[0104] G3: Sodium antimonate, YC-278, purchased from Hubei Yongcheng Industrial Co., Ltd.

[0105] (8) Phosphorus-nitrogen flame retardants

[0106] H1: Ammonium polyphosphate, XS-APPII-040, purchased from Shanghai Xusen Non-halogenated Smoke Retardant Flame Retardant Co., Ltd.;

[0107] H2: Melamine polyphosphate, XS-MPP, purchased from Shanghai Xusen Non-halogenated Smoke Retardant Flame Retardant Co., Ltd.

[0108] H3: Phosphazene compound, TP100, purchased from Hubei Xinyuhong Biomedical Technology Co., Ltd.

[0109] (9) Curing accelerator

[0110] 2-Methylimidazole, TD-230, was purchased from Hubei Xingyinhe Chemical Co., Ltd.

[0111] Example 1

[0112] An adhesive sheet includes a reinforcing material and a resin composition attached to the reinforcing material by a double impregnation-drying process; the resin composition includes a first resin composition attached after a first impregnation-drying and a second resin composition attached after a second impregnation-drying; the first resin composition, by weight, comprises: 100 parts of waterborne phenolic resin, 8 parts of nitrogen-containing flame retardant B1, and 15 parts of phosphorus-containing flame retardant C1; the second resin composition, by weight, comprises: 100 parts of epoxy resin D1, 50 parts of linear phenolic resin, 10 parts of halogenated flame retardant F1, 5 parts of antimony-based flame retardant G1, 7.5 parts of phosphorus-nitrogen flame retardant H1, and 0.1 parts of curing accelerator.

[0113] The adhesive sheet is prepared as follows:

[0114] (1) According to the above formula, add water-based phenolic resin, nitrogen-containing flame retardant, phosphorus-containing flame retardant and water into a container, stir to mix evenly, and finally adjust the solid content with water to 20% to obtain the first adhesive solution; use wood pulp fiber paper to impregnate the first adhesive solution for 10 s, and then dry at 220℃ for 4 min to obtain the prepreg.

[0115] (2) According to the above formula, epoxy resin, linear phenolic resin, halogenated flame retardant, antimony flame retardant, phosphorus-nitrogen flame retardant, curing accelerator and acetone are added to a container and stirred to make them evenly mixed. Finally, the solid content is adjusted to 60% with acetone to obtain the second adhesive liquid. The prepreg obtained in step (1) is used to impregnate the second adhesive liquid for 12 s, and then dried at 180°C for 3 min to obtain the adhesive sheet.

[0116] A CEM-1 copper clad laminate includes a laminate and copper foil disposed on both sides of the laminate. The laminate includes a face sheet and a core material, wherein the core material is an adhesive sheet provided in this embodiment. The specific preparation method is as follows: five adhesive sheets provided in this embodiment are stacked to form the core material. A face sheet (glass fiber cloth-based prepreg) is placed on both sides of the core material stack. Copper foil is then covered on both sides of the outer side of the face sheet. The core material is hot-pressed at 160°C and 5 MPa for 120 min in a press to produce a 1.6 mm CEM-1 copper clad laminate.

[0117] Examples 2-13, Comparative Examples 1-3

[0118] An adhesive sheet differs from Example 1 only in that the components of the first resin composition and / or the second resin composition are different, and the specific formulations are shown in Tables 1 and 2; the amount of each component in Tables 1 and 2 is in "parts"; the preparation method of the adhesive sheet is the same as that of Example 1.

[0119] The bonding sheets provided in Examples 2-13 and Comparative Examples 1-3 were prepared into CEM-1 copper-clad laminates using the method described in Example 1, and the following physical property evaluation tests were performed:

[0120] (1) Thermal stress: The thermal stress test method specified in GB / T 4722-2017 was used to measure the floating weld and dip weld at 288℃ respectively;

[0121] (2) Punching performance: The punching performance shall be determined in accordance with the punching performance test method specified in GB / T 4722-2017; and tested in accordance with UL-94 standard.

[0122] (3) Flame retardancy: Tested according to UL94 “50 W (20 mm) vertical burning test: V-0, V-1 and V-2” test method;

[0123] (4) Thermal delamination time T260: The time before the delamination of the board material occurs due to heat at a set temperature of 260℃;

[0124] (5) Water absorption rate: determined according to IPC-TM-6502.6.2.1.

[0125] The test results are shown in Tables 1 and 2 below.

[0126] Table 1

[0127]

[0128] Table 2

[0129]

[0130] Comparative Example 4

[0131] An adhesive sheet differs from Example 1 only in that the first resin composition comprises, by weight, 100 parts of waterborne phenolic resin; and the second resin composition comprises, by weight, 100 parts of epoxy resin D1, 50 parts of linear phenolic resin, 0.1 parts of curing accelerator, 10 parts of halogenated flame retardant F1, 5 parts of antimony-based flame retardant G1, 7.5 parts of phosphorus-nitrogen flame retardant H1, 8 parts of nitrogen-containing flame retardant B1, and 15 parts of phosphorus-containing flame retardant C1.

[0132] The adhesive sheet is prepared as follows:

[0133] (1) According to the above formula, add water-based phenolic resin and water into a container, stir to mix evenly, and finally adjust the solid content to 20% with water to obtain the first adhesive solution; use wood pulp fiber paper to impregnate the first adhesive solution for 10 s, and then dry at 220℃ for 4 min to obtain the prepreg.

[0134] (2) According to the above formula, epoxy resin, linear phenolic resin, halogenated flame retardant, antimony flame retardant, phosphorus-nitrogen flame retardant, curing accelerator, nitrogen-containing flame retardant, phosphorus-containing flame retardant and acetone are added to a container and stirred to make them evenly mixed. Finally, the solid content is adjusted to 60% with acetone to obtain the second adhesive liquid. The prepreg obtained in step (1) is used to impregnate the second adhesive liquid for 18 s, and then dried at 180°C for 3 min to obtain the adhesive sheet.

[0135] Comparative Example 5

[0136] An adhesive sheet differs from Example 1 only in that the first resin composition comprises, by weight, 100 parts of waterborne phenolic resin, 10 parts of halogenated flame retardant F1, 5 parts of antimony-based flame retardant G1, and 7.5 parts of phosphorus-nitrogen flame retardant H1; and the second resin composition comprises, by weight, 100 parts of epoxy resin D1, 50 parts of linear phenolic resin, 0.1 parts of curing accelerator, 8 parts of nitrogen-containing flame retardant B1, and 15 parts of phosphorus-containing flame retardant C1.

[0137] The adhesive sheet is prepared as follows:

[0138] (1) According to the above formula, add water-based phenolic resin, halogenated flame retardant, antimony flame retardant, phosphorus-nitrogen flame retardant and water into a container, stir to mix evenly, and finally adjust the solid content with water to 20% to obtain the first adhesive solution; use wood pulp fiber paper to impregnate the first adhesive solution for 16 s, and then dry at 220℃ for 4 min to obtain the prepreg.

[0139] (2) According to the above formula, epoxy resin, linear phenolic resin, curing accelerator, nitrogen-containing flame retardant, phosphorus-containing flame retardant and acetone are added to a container and stirred to make them evenly mixed. Finally, the solid content is adjusted to 60% with acetone to obtain the second adhesive liquid. The prepreg obtained in step (1) is used to impregnate the second adhesive liquid for 12 s, and then dried at 180°C for 3 min to obtain the adhesive sheet.

[0140] Comparative Example 6

[0141] An adhesive sheet differs from Example 1 only in that the first resin composition comprises, by weight, 100 parts of waterborne phenolic resin, 8 parts of nitrogen-containing flame retardant B1, 15 parts of phosphorus-containing flame retardant C1, 10 parts of halogen-based flame retardant F1, 5 parts of antimony-based flame retardant G1, and 7.5 parts of phosphorus-nitrogen flame retardant H1; and the second resin composition comprises, by weight, 100 parts of epoxy resin D1, 50 parts of linear phenolic resin, and 0.1 parts of curing accelerator.

[0142] The adhesive sheet is prepared as follows:

[0143] (1) According to the above formula, add water-based phenolic resin, nitrogen-containing flame retardant, phosphorus-containing flame retardant, halogen-based flame retardant, antimony-based flame retardant, phosphorus-nitrogen flame retardant and water into a container, stir to mix evenly, and finally adjust the solid content with water to 20% to obtain the first adhesive solution; use wood pulp fiber paper to impregnate the first adhesive solution for 18s, and then dry at 220℃ for 4 min to obtain the prepreg;

[0144] (2) According to the above formula, epoxy resin, linear phenolic resin, curing accelerator and acetone are added to the container and stirred to make them evenly mixed. Finally, the solid content is adjusted to 60% with acetone to obtain the second adhesive liquid. The second adhesive liquid is impregnated with the prepreg obtained in step (1) for 12 s, and then dried at 180°C for 3 min to obtain the adhesive sheet.

[0145] Comparative Example 7

[0146] An adhesive sheet differs from Example 1 only in that the first resin composition comprises, by weight, 100 parts of waterborne phenolic resin, 8 parts of nitrogen-containing flame retardant B1, 15 parts of phosphorus-containing flame retardant C1, and 7.5 parts of phosphorus-nitrogen flame retardant H1; and the second resin composition comprises, by weight, 100 parts of epoxy resin D1, 50 parts of linear phenolic resin, 10 parts of halogenated flame retardant F1, 5 parts of antimony-based flame retardant G1, and 0.1 parts of curing accelerator.

[0147] The adhesive sheet is prepared as follows:

[0148] (1) According to the above formula, add water-based phenolic resin, nitrogen-containing flame retardant, phosphorus-containing flame retardant, phosphorus-nitrogen flame retardant and water into a container, stir to mix evenly, and finally adjust the solid content with water to 20% to obtain the first adhesive solution; use wood pulp fiber paper to impregnate the first adhesive solution for 16 s, and then dry at 220℃ for 4 min to obtain the prepreg.

[0149] (2) According to the above formula, epoxy resin, linear phenolic resin, halogenated flame retardant, antimony flame retardant, curing accelerator and acetone are added to a container and stirred to mix evenly. Finally, the solid content is adjusted to 60% with acetone to obtain the second adhesive liquid. The prepreg obtained in step (1) is used to impregnate the second adhesive liquid for 13 s, and then dried at 180°C for 3 min to obtain the adhesive sheet.

[0150] The bonding sheets provided in Comparative Examples 4-7 were prepared into CEM-1 copper-clad laminates using the method described in Example 1, and their performance was tested using the same method. The test results are shown in Table 3.

[0151] Table 3

[0152]

[0153] Based on the performance data in Tables 1, 2, and 3, it can be seen that the present invention improves the flame retardancy, heat resistance, and processability of the adhesive sheet through the design and synergy of the first and second resin compositions. Through further optimization of the components in the resin compositions, the CEM-1 copper-clad laminates provided in Examples 1-9 achieve a flame retardancy rating of V-0, a punching processability rating of 5, a thermal stress (288°C, floating solder) of 162-205 s, a thermal stress (288°C, dip solder) of 108-137 s, a T260 of 83-97 min, and a water absorption rate of 0.08-0.1%. It combines excellent flame retardancy, heat resistance, and punching processability with low water absorption, resulting in better overall performance.

[0154] Furthermore, analysis of Examples 1-9 and Examples 10-13 reveals that the heat resistance of Example 10 is significantly reduced, the punching processability of Examples 11 and 13 is significantly insufficient, and the flame retardancy of Example 12 is low. Therefore, it is evident that in the second resin composition of the present invention, when the halogen-based flame retardant is 5-15 parts, the antimony-based flame retardant is 2-8 parts, and the phosphorus-nitrogen flame retardant is 5-10 parts, the components work synergistically to achieve a better balance between heat resistance, punching processability, and flame retardancy in the copper-clad laminate.

[0155] Analysis of Examples 1-9 and Comparative Examples 1-3 shows that the flame retardancy of Comparative Example 1 is significantly reduced, the heat resistance of Comparative Example 2 is poor, and both the heat resistance and perforation properties of Comparative Example 3 are reduced. Therefore, this invention, through the design and compounding of the first and second resin compositions, especially by introducing phosphorus-nitrogen flame retardants, antimony-based flame retardants, and halogen-based flame retardants into the second resin composition to construct a compound flame retardant system, significantly contributes to the flame retardancy of copper-clad laminates, greatly reduces the amount of halogen-based flame retardants used, and significantly improves heat resistance and processability.

[0156] Analysis of Example 1 and Comparative Examples 4-7 shows that the heat resistance, flame retardancy, and perforation properties of Comparative Examples 4-7 decreased to varying degrees, while the water absorption rate increased. This indicates that the present invention uses a first resin combined with a nitrogen-containing flame retardant and a phosphorus-containing flame retardant, and a second resin combined with an antimony-based flame retardant, a halogen-based flame retardant, and a phosphorus-nitrogen flame retardant. Through the specific design of the impregnation sequence of the first and second adhesive solutions, the copper-clad laminate can simultaneously possess excellent heat resistance, flame retardancy, perforation properties, and low water absorption rate.

[0157] The applicant declares that the present invention is illustrated by the above embodiments to demonstrate the adhesive sheet, its preparation method, and its application. 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 product 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. An adhesive sheet, characterized in that, The adhesive sheet includes a reinforcing material and a resin composition that is attached to the reinforcing material by a double impregnation and drying process; The resin composition includes a first resin composition that adheres after a first impregnation and drying and a second resin composition that adheres after a second impregnation and drying; The first resin composition comprises a combination of phenolic resin, a nitrogen-containing flame retardant, and a phosphorus-containing flame retardant; Based on 100 parts by weight of the phenolic resin, the nitrogen-containing flame retardant comprises 5-10 parts by weight; and the phosphorus-containing flame retardant comprises 10-20 parts by weight. The phosphorus-containing flame retardant includes any one or a combination of at least two of the following: alkoxycyclotriphosphazene, phenoxycyclotriphosphazene, hexa-p-aldehyde phenoxycyclotriphosphazene, hexa(4-DOPO hydroxymethylphenoxy)cyclotriphosphazene, (2-allylphenoxy)pentaphenoxycyclotriphosphazene, and hexa(4-nitrophenoxy)cyclotriphosphazene. The phenolic resin is an aqueous phenolic resin; The number-average molecular weight of the phenolic resin is 100-2000 g / mol; The second resin composition comprises a combination of epoxy resin, curing agent, halogenated flame retardant, antimony-based flame retardant, and phosphorus-nitrogen flame retardant; Based on 100 parts by weight of the epoxy resin, the halogenated flame retardant comprises 5-15 parts by weight, the antimony-based flame retardant comprises 2-8 parts by weight, and the phosphorus-nitrogen flame retardant comprises 5-10 parts by weight. The phosphorus-nitrogen flame retardant includes any one or a combination of at least two of the following: ammonium polyphosphate, melamine polyphosphate, and phosphazene compounds.

2. The adhesive sheet according to claim 1, characterized in that, The nitrogen-containing flame retardant includes any one or a combination of at least two of the following: vinyl isocyanate, melamine-glyoxal resin, melamine-formaldehyde resin, methylated melamine resin, butylated melamine resin, triisocyanurate-modified melamine resin, and organosilicon-modified melamine resin.

3. The adhesive sheet according to claim 1, characterized in that, The epoxy resin includes any one or a combination of at least two of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and bisphenol S type epoxy resin.

4. The adhesive sheet according to claim 1, characterized in that, The curing agent comprises 20-80 parts by weight of 100 parts of epoxy resin.

5. The adhesive sheet according to claim 1, characterized in that, The curing agent includes any one or a combination of at least two of the following: vegetable oil modified phenolic resin, linear phenolic resin, and thermosetting phenolic resin.

6. The adhesive sheet according to claim 1, characterized in that, The halogenated flame retardant includes any one or a combination of at least two of tetrabromobisphenol A, tribromophenol, decabromodiphenyl ethane, and octabromodiphenyl ethane.

7. The adhesive sheet according to claim 1, characterized in that, The antimony-based flame retardant includes any one or a combination of at least two of antimony oxide, antimony halide, and antimonates.

8. The adhesive sheet according to claim 1, characterized in that, The second resin composition also includes a curing accelerator.

9. The adhesive sheet according to claim 8, characterized in that, Based on 100 parts by weight of the epoxy resin, the mass of the curing accelerator is ≤1 part.

10. The adhesive sheet according to claim 8, characterized in that, The curing accelerator includes any one or a combination of at least two of the following: tertiary amines, tertiary phosphine, organometallic complexes, imidazole compounds, and quaternary ammonium salts.

11. The adhesive sheet according to claim 1, characterized in that, The reinforcing material includes at least one of wood pulp paper, cotton pulp paper, or nonwoven fabric.

12. A method for preparing an adhesive sheet as described in any one of claims 1-11, characterized in that, The preparation method includes: The reinforcing material is first impregnated in the adhesive solution of the first resin composition and then first dried to obtain a prepreg. The prepreg is immersed in the adhesive solution of the second resin composition for a second time and then dried for a second time to obtain the adhesive sheet.

13. A metal foil-coated laminate, characterized in that, The metal foil laminate comprises a metal foil and at least one adhesive sheet as described in any one of claims 1-11.

14. The metal foil-coated laminate according to claim 13, characterized in that, The metal foil laminate is a CEM-1 copper clad laminate, which includes a laminate and copper foil disposed on one or both sides of the laminate; the laminate includes a face material and a core material, and the core material includes at least one adhesive sheet as described in any one of claims 1-11.

15. A printed circuit board, characterized in that, The printed circuit board includes an adhesive sheet as described in any one of claims 1-11 and / or a metal foil laminate as described in claim 13 or 14.

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