阅读说明：本技术 树脂组合物及使用其制作的低流胶半固化片 (Resin composition and low-flow-rate prepreg prepared from same ) 是由 何继亮 王宁 陈诚 崔春梅 储正振 于 2020-12-21 设计创作，主要内容包括：本发明开发了一种树脂组合物,以重量计,包括如下组分：(a)环氧树脂；(b)含马来酰亚胺基的酚醛树脂；(c)环氧树脂固化促进剂；(d)韧性树脂；(e)含有不饱和双键的液体树脂。本发明通过在树脂体系中引入了强极性且帯可反应双键的对羟基苯基马来酰亚胺结构,实验证明：使用该树脂组合物制备的低流胶半固化片和软板聚酰亚胺面结合力优异,同时还备有优异的耐热性能、韧性和掉粉性,非常适用于刚挠结合印制电路板等特殊PCB的制作,具有很强的加工适应性和质量可靠性。(The invention discloses a resin composition which comprises the following components in parts by weight: (a) an epoxy resin; (b) a maleimide group-containing phenol resin; (c) an epoxy resin curing accelerator; (d) a tough resin; (e) a liquid resin containing unsaturated double bonds. According to the invention, a p-hydroxyphenyl maleimide structure with strong polarity and a reactive double bond is introduced into a resin system, and experiments prove that: the low-flow-rate prepreg and the soft board polyimide surface prepared by using the resin composition have excellent binding force, excellent heat resistance, toughness and powder dropping property, are very suitable for manufacturing special PCBs (printed circuit boards) such as rigid-flexible combined printed circuit boards, and have very strong processing adaptability and quality reliability.)

1. A resin composition is characterized by comprising the following components in parts by weight:

(a) 100 parts of epoxy resin;

(b) a maleimide group-containing phenol resin;

(c) 0.05-5 parts of epoxy resin curing accelerator;

(d) a tough resin;

(e) a liquid resin containing unsaturated double bonds;

the component (b) is added in the following amount: the functional equivalent ratio of the epoxy resin to the phenolic resin containing maleimide groups is 1: 0.5 to 5;

the component (d) is added in the following amount: the weight ratio of the tough resin to other components is 1-20: 100, respectively;

the structural formula of the component (b) is as follows:wherein x is an integer of 1 to 20, y is an integer of 0 to 20, and n is an integer of 1 to 10; ar is a group containing one or more benzene rings, and Ar is a group containing more than one hydroxyphenyl;

the component (e) is added in the following amount: the double bond functional equivalent ratio of the liquid resin containing unsaturated double bonds to the phenolic resin containing maleimide groups is 1: 0.5 to 10.

2. The resin composition according to claim 1, characterized in that: and Ar is a benzene ring.

3. The resin composition according to claim 1, characterized in that: ar is selected from one or more of the following structures:

4. the resin composition according to claim 1, characterized in that: in the structural formula of the component (b), the molar ratio of the x structural unit to the y structural unit is 1: 1-1: 5.

5. the resin composition according to claim 1, characterized in that: the epoxy resin is selected from one or more of DOPO-HQ modified epoxy resin, biphenyl epoxy resin, bisphenol novolac epoxy resin, bisphenol A-containing epoxy resin, bisphenol F epoxy resin, dihydroxy diphenyl ether epoxy resin and allyl glycidyl ether.

6. The resin composition according to claim 1, characterized in that: the tough resin is selected from one or more of phenoxy resin, nitrile rubber, core-shell rubber and polyacrylate resin.

7. The resin composition according to claim 1, characterized in that: the curing agent also comprises a co-curing agent, wherein the addition amount of the co-curing agent is as follows: and (3) according to the functional equivalent calculation, the ratio of the total functional equivalent of the phenolic resin containing maleimide groups and the co-curing agent to the functional equivalent of the epoxy resin is 0.5-5: 1, the maleimide group-containing phenolic resin accounts for 50-90% of the total functional equivalent of the curing agent; preferably, the co-curing agent is an amine curing agent.

8. The resin composition according to claim 1, characterized in that: the resin composition further comprises a filler, wherein the filler accounts for 5-80% of the resin composition by weight.

9. The resin composition according to claim 1, characterized in that: the liquid resin containing unsaturated double bonds is selected from one or more of acrylic resin, allyl resin, styrene and substituted styrene resin; preferably, the addition amount of the liquid resin containing unsaturated double bonds is 1 to 10 percent of the weight ratio of the liquid resin containing unsaturated double bonds to other total resins.

10. A low flow prepreg prepared using the resin composition as claimed in any one of claims 1 to 9.

Technical Field

The invention relates to the technical field of electronic materials, in particular to a resin composition and a low-flow-rate prepreg manufactured by using the same.

Background

Currently, a rigid-flex printed circuit board (also referred to as a rigid-flex printed circuit board) is a printed circuit board which is in current demand and development. The rigid-flex printed circuit board is formed by combining a thin-layer flexible bottom layer and a rigid bottom layer and then laminating the thin-layer flexible bottom layer and the rigid bottom layer into a single component, and the rigid-flex printed circuit board changes the traditional planar design concept and expands the three-dimensional 3-dimensional space concept, thereby bringing great convenience to product design and simultaneously bringing great challenges. A typical (four-layer) flex-rigid printed circuit board has a polyimide core with copper clad on both its top and bottom surfaces. The outer rigid layer consists of FR4 on one side, which are laminated to both sides of the flexible core to assemble a multilayer PCB. The process of fabricating the flex layer is again distinct from the outer FR4 layer in making a multi-layer flex-rigid panel. The individual layers made of different materials must be brought together by lamination and then drilled and plated. Thus, the time to make a typical four-layer rigid-flex printed circuit board may be 5 to 7 times longer than making a standard four-layer rigid printed circuit board. At present, the application range of the rigid-flex printed circuit board mainly comprises: aerospace, such as high-end aircraft weapon navigation systems, advanced medical devices, digital cameras, camcorders and high quality MP3 players. Rigid-flex boards are most commonly used in the manufacture of military aircraft and medical equipment. The rigid-flex board provides a great benefit to the design of military aircraft because it reduces weight while improving connection reliability.

The rigid-flexible printed circuit board needs to be bonded with a soft board and a hard board by using a bonding material during processing and manufacturing, and the most common bonding material at the present stage is a low-fluidity prepreg. Compared with the conventional FR-4 prepreg, the low resin fluidity prepreg needs to have the characteristic of little or no flow of glue under high temperature and high pressure, and also needs to have good adhesion, excellent toughness and low powder falling property. Due to the very low or almost no flow of the low-flow prepregs at high temperatures and pressures, it is generally necessary to increase the degree of reaction of the resin system, which leads to a reduction in the bonding capacity of the bonding sheets. Particularly, the bonding force between the low-flow prepreg and the polyimide surface of the flexible printed circuit board is one of the factors which seriously affect the reliability of the flexible-rigid printed circuit board.

In order to solve the problem of the bonding force between the low flow rate prepreg and the polyimide surface of the flexible printed circuit board, in chinese patent application CN104164087A, a thermosetting resin composition comprising allyl modified bismaleimide resin and an epoxy resin with a special structure is used. However, the technical solution in the patent has a problem of large powder falling caused by insufficient toughness, and the processing performance of the printed circuit board is seriously affected. In order to improve the toughness of low flow prepreg, too much bisphenol a type epoxy resin is added, which in turn causes a problem that the glass transition temperature becomes low.

In order to improve the toughness and the powder dropping property of the low-flow-rate prepreg, in the prior art, macromolecular polymers such as phenoxy resin, nitrile rubber, polyacrylate resin and the like are usually added into a resin system, however, the macromolecular polymers can cause the reduction of the wettability of the resin system on glass fiber cloth, and form defects such as resin cavities in the prepreg, which can cause the reduction of the reliability of the low-flow-rate prepreg after being pressed.

Therefore, the development of a novel resin composition and a low-flow-rate prepreg manufactured by using the same can improve the binding force between the low-flow-rate prepreg and a soft plate polyimide surface, ensure that the low-flow-rate prepreg has excellent heat resistance, toughness and low powder falling property, avoid the problem of reduced wettability of a resin system on glass fiber cloth, and obviously have positive practical significance.

Disclosure of Invention

The invention aims to provide a resin composition and a low-flow prepreg manufactured by using the same.

In order to achieve the purpose of the invention, the technical scheme adopted by the invention is as follows: a resin composition comprises the following components in parts by weight:

(a) 100 parts of epoxy resin;

(b) a maleimide group-containing phenol resin;

(c) 0.05-5 parts of epoxy resin curing accelerator;

(d) a tough resin;

(e) a liquid resin containing unsaturated double bonds;

the component (b) is added in the following amount: the functional equivalent ratio of the epoxy resin to the phenolic resin containing maleimide groups is 1: 0.5 to 5;

the component (d) is added in the following amount: the weight ratio of the tough resin to other components is 1-20: 100, respectively;

the structural formula of the component (b) is as follows:

wherein x is an integer of 1 to 20, y is an integer of 0 to 20, and n is an integer of 1 to 10; ar is a group containing one or more benzene rings, and Ar is a group containing more than one hydroxyphenyl;

the component (e) is added in the following amount: the double bond functional equivalent ratio of the liquid resin containing unsaturated double bonds to the phenolic resin containing maleimide groups is 1: 0.5 to 10.

As described above, the epoxy resin may be one or more selected from the group consisting of a phosphorous epoxy resin, a nitrogen-containing epoxy resin, a polyfunctional epoxy resin, a bisphenol a epoxy resin, a bisphenol F epoxy resin, a tetraphenylethane epoxy resin, a triphenylmethane epoxy resin, a biphenyl epoxy resin, a naphthalene ring epoxy resin, a dicyclopentadiene epoxy resin, an isocyanate epoxy resin, a novolac epoxy resin, a methyl novolac epoxy resin, a bisphenol novolac epoxy resin, a polyphenylene ether-modified epoxy resin, an alicyclic epoxy resin, an allyl glycidyl epoxy resin, a glycidyl amine epoxy resin, and a glycidyl ester epoxy resin.

In order to ensure that the bonding force between the obtained low-flow-glue prepreg and the polyimide surface of the soft board is good, preferably, the epoxy resin contains one or more of DOPO-HQ type phosphorus-containing epoxy resin, biphenyl type epoxy resin and bisphenol type novolac epoxy resin; more preferably, the epoxy resin comprises bisphenol type novolac epoxy resin, and the bisphenol type novolac epoxy resin can be bisphenol A type novolac epoxy resin, bisphenol F type novolac epoxy resin, bisphenol S type novolac epoxy resin, or dihydroxy diphenyl ether type novolac epoxy resin.

In order to ensure that the resin system in the obtained low-flow-rate prepreg has good wettability to glass fiber cloth and avoid the defects of resin voids and the like formed in the prepreg, the epoxy resin preferably contains one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, dihydroxy diphenyl ether epoxy resin, allyl glycidyl ether, N, N, N ', N ' -tetracyclooxypropyl-4, 4' -diaminodiphenylmethane and other small-molecule epoxy resins.

Preferably, in order to make the obtained low-flow adhesive bonding sheet have better anti-sticking property and heat resistance, when the epoxy resin comprises one or more of bisphenol a epoxy resin, bisphenol F epoxy resin, dihydroxy diphenyl ether epoxy resin and allyl glycidyl ether, the addition amount of the bisphenol a epoxy resin, the bisphenol F epoxy resin, the dihydroxy diphenyl ether epoxy resin and the allyl glycidyl ether is 1-15% of the total solid content of the total resin composition.

Hereinbefore, the component (b) is added in the following amounts: the functional equivalent ratio of the epoxy resin to the phenolic resin containing maleimide groups is 1: 0.5 to 5; preferably 1: 0.6 to 4, more preferably 1: 0.8-3, preferably 1:1 to 2.

The component (d) is added in the following amount: the weight ratio of the tough resin to other components is 1-20: 100, respectively; preferably 1-15: 100, more preferably 2 to 10: 100, more preferably 3 to 8: 100, more preferably 4 to 6: 100.

the component (e) is added in the following amount: the double bond functional equivalent ratio of the liquid resin containing unsaturated double bonds to the phenolic resin containing maleimide groups is 1: 0.5 to 10. Preferably 100: 1-8, more preferably 100: 2-5, more preferably 100: 3 to 4.

The resin composition of the present invention may further include a flame retardant, which may be a phosphorus flame retardant, a nitrogen flame retardant, an organosilicon flame retardant, an inorganic flame retardant, and the like. The phosphorus-containing flame retardant may be an organic phosphorus-containing compound such as a phosphorus-containing epoxy resin, a phosphorus-containing phenol resin, inorganic phosphorus, a phosphate ester compound, a phosphonic acid compound, a phosphinic acid compound, a phosphine oxide compound, 9, 10-dihydro-9 oxa-10-phosphaphenanthrene-10-oxide, 10- (2, 5-dihydroxyphenyl) -9, 10-dihydro-9 oxa-10-phosphaphenanthrene-10-oxide, 10-phenyl-9, 10-dihydro-9 oxa-10-phosphaphenanthrene-10-oxide, tris (2, 6-dimethylphenyl) phosphazene, or the like. The nitrogen-based flame retardant may be a triazine compound, a cyanuric acid compound, an isocyanic acid compound, phenothiazine, or the like. The organic silicon flame retardant can be organic silicon oil, organic silicon rubber, organic silicon resin and the like. The inorganic flame retardant may be aluminum hydroxide, magnesium hydroxide, aluminum oxide, barium oxide, or the like.

In the technical scheme, the epoxy resin curing accelerator is selected from one or more of imidazole accelerators, amine accelerators, tin accelerators and modified DBN/DBU. The imidazole accelerator may be 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, or the like. The amine accelerator can be triethylene diamine, N-amino morpholine, boron trifluoride ethylamine and the like. The tin accelerator may be dibutyltin dilaurate, stannous octoate, or the like.

Preferably, Ar is a benzene ring.

Preferably, Ar is selected from one or more of the following structures:

preferably, in the structural formula of the component (b), the molar ratio of the x structural unit to the y structural unit is 1:1 to 5.

In the technical scheme, the epoxy resin is selected from one or more of DOPO-HQ modified epoxy resin, biphenyl epoxy resin, bisphenol novolac epoxy resin, bisphenol A-containing epoxy resin, bisphenol F epoxy resin, dihydroxy diphenyl ether epoxy resin and allyl glycidyl ether.

In the technical scheme, the tough resin is selected from one or more of phenoxy resin, nitrile rubber, core-shell rubber and polyacrylate resin.

The phenoxy resin can be selected from one or more of allyl phenoxy resin, phosphorus-containing phenoxy resin, sulfur-containing phenoxy resin, bisphenol A glycidyl ether type, bisphenol F glycidyl ether type or biphenyl type glycidyl ether type phenoxy resin; preferably, the weight-average molecular weight of the copolymer is 5000-70000.

The nitrile rubber can be selected from carboxyl nitrile rubber, amino nitrile rubber or other modified nitrile rubber, preferably solid rubber or modified solid rubber with larger molecular weight, and more preferably, the weight average molecular weight of the nitrile rubber is 50000-300000.

The polyacrylate resin may be selected from the group consisting of acrylate-type homopolymers, copolymers of other vinyl monomers and acrylates. Preferably, the polyacrylate is an acrylate triblock copolymer. The acrylate triblock copolymer refers to a triblock copolymer comprising a middle flexible segment and two hard segments at the two ends. The middle flexible block can be a block with good flexibility, such as polybutyl acrylate, polybutyl methacrylate, polyethyl acrylate, isooctyl acrylate, 2-ethylhexyl methacrylate, polybutadiene, or the like; the hard segments at the two ends can be blocks with better rigidity, such as polymethacrylate, polystyrene and the like. Preferably, the acrylate triblock copolymer is a polystyrene-polybutadiene-polymethacrylate triblock copolymer or a polymethyl methacrylate-polybutyl acrylate-polymethyl methacrylate triblock copolymer. Preferably, the weight average molecular weight of the acrylate triblock copolymer is 10000-800000, and more preferably, the weight average molecular weight of the acrylate triblock copolymer is 10000-300000. When the molecular weight is large, the toughness and heat resistance of the acrylate are good, but there may be a problem of compatibility with other resins. In order to improve the compatibility of the acrylate with other resins, the acrylate block copolymer may be functionally modified, and may be modified by hydroxyl group functionalization, carboxyl group functionalization, amino group functionalization, and epoxy group functionalization. The amount of the polyacrylate resin added is preferably 1 to 10 parts by weight based on 100 parts by weight of the epoxy resin. When the molecular weight of the acrylate is higher, the addition amount of the acrylate can be properly reduced to improve the compatibility of the acrylate with other resins, and the preferable addition amount is 1 to 5 parts by weight.

In the technical scheme, the curing agent further comprises a co-curing agent, wherein the addition amount of the co-curing agent is as follows: and (3) according to the functional equivalent calculation, the ratio of the total functional equivalent of the phenolic resin containing maleimide groups and the co-curing agent to the functional equivalent of the epoxy resin is 0.5-5: 1, the maleimide group-containing phenolic resin accounts for 50-90% of the total functional equivalent of the curing agent. Preferably 60 to 80%, more preferably 70 to 77%.

The co-curing agent may be: aliphatic amine, aromatic amine, alicyclic amine, heterocyclic amine, polyamide-polyamine, modified polyamine compound, dicyandiamide, aromatic acid anhydride, alicyclic acid anhydride, aliphatic acid anhydride, polyamide resin, phenol novolac resin, benzoxazine resin, polyphenol resin, arylamine formaldehyde resin, polysulfide compound, polyester resin, latent curing agent, flame retardant curing agent, active ester curing agent, or a mixture of any of them. The co-curing agent is preferably an amine curing agent.

In order to ensure that the bonding force between the low-flow-rubber prepreg and the polyimide surface of the soft board is good, the co-curing agent is preferably dicyandiamide.

In order to obtain the low-flow-rate prepreg with high heat resistance and ensure that the low-flow-rate prepreg and the soft plate polyimide surface have good bonding force, preferably, the co-curing agent is diaminodiphenyl sulfone and diaminodiphenyl ether.

In the technical scheme, the resin composition further comprises a filler, wherein the filler accounts for 5-80% of the resin composition by weight. The filler can be one or more selected from crystalline silica, fused silica, spherical silica, alumina, aluminum hydroxide, aluminum nitride, boron nitride, titanium dioxide, strontium titanate, barium sulfate, talcum powder, calcium silicate, calcium carbonate, mica, polytetrafluoroethylene and graphene. The filler may be surface-treated with a silane coupling agent, and may be directly charged or may be preliminarily prepared into a filler dispersion or may be charged into a resin composition in the form of a paste. The particle size of the filler is preferably 0.5-10 micrometers (particle size D50). In order to obtain a low flow prepreg with excellent fraction loss, the filler content is preferably: the filler accounts for 5-10% of the resin composition. In order to enable the obtained low-flow prepreg to have excellent rigidity and thermal conductivity, the content ratio of the filler is preferably 50-70%. In order to obtain a low flow prepreg having excellent thermal conductivity and excellent interlayer adhesion and copper foil adhesion, the preferred filler is alumina.

In addition, the resin composition of the present invention may further include a special functional auxiliary agent such as a dispersant, a coupling agent, a defoaming agent, a leveling agent, a coloring agent, a compatibilizing agent, a UV blocking agent, and the like.

Preferably, when the epoxy resin contains one or more of bisphenol a epoxy resin, bisphenol F epoxy resin, dihydroxy diphenyl ether epoxy resin, allyl glycidyl ether, N '-tetracyclooxypropyl-4, 4' -diaminodiphenylmethane, the addition amount of the bisphenol a epoxy resin, bisphenol F epoxy resin, dihydroxy diphenyl ether epoxy resin, allyl glycidyl ether, N '-tetracyclooxypropyl-4, 4' -diaminodiphenylmethane is 1-15% of the total solid content of the resin composition.

In the above technical scheme, the liquid resin containing unsaturated double bonds is selected from one or more of acrylic resin, allyl resin, styrene and substituted styrene resin. The addition amount of the unsaturated double-bond liquid resin is 1-10% of the weight ratio of the unsaturated double-bond liquid resin to other total resins.

The acrylic resin may be one or any of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, glycidyl methacrylate, isobornyl methacrylate, phenoxyethyl acrylate, tetrahydrofurfuryl methacrylate, diethylene glycol acrylate, triethylene glycol acrylate, polyethylene glycol acrylate, diethylene glycol acrylate, triethylene glycol acrylate, neopentyl glycol diacrylate, diethylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, methacrylic acid phosphate, alkoxy trifunctional acrylate, aliphatic monoacrylate, tertiary amine acrylate, alkoxylated diacrylate. In order to obtain a low-flow prepreg with better bonding performance, the acrylic resin is preferably one or any one of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, glycidyl methacrylate and methacrylic acid phosphate. In order to obtain the low-flow-rubber prepreg with better toughness, the acrylic resin is preferably polyethylene glycol acrylate. In order to obtain a thermosetting resin composition having better filler dispersibility, it is preferable that the acrylate resin is an alkoxylated diacrylate.

The allyl resin can be one or more of allyl bisphenol A, allyl bisphenol S, diallyl diphenyl ether, allyl cresol, allyl glycidyl ether and allyl resin modified maleimide prepolymer. In order to obtain better adhesion between the low-flow prepreg and the soft polyimide surface, the allyl resin is preferably diallyl diphenyl ether or allyl cresol modified maleimide prepolymer. In order to obtain a resin composition with better glass fiber cloth wettability, the allyl resin is preferably allyl cresol and allyl cresol modified maleimide prepolymer.

Preferably, to obtain better adhesion of the low flow prepreg to the flexographic polyimide side, the substituted styrene is preferably hydroxystyrene.

The invention also discloses a low-flow prepreg prepared by adopting the resin composition.

The preparation method of the low-flow prepreg comprises the following steps: adding the resin composition and a solvent into a glue mixing kettle, uniformly stirring the resin composition and the solvent until the solid content is 40-70%, and curing the mixture for 4-8 hours to prepare a resin composition glue solution; and then, soaking the reinforcing material in the resin composition glue solution, and then reacting and drying the soaked reinforcing material at the temperature of 100-200 ℃ according to a set program to obtain the low-flow-rate prepreg. The reinforcing material is natural fiber, organic synthetic fiber, organic fabric or inorganic fabric. The diluent is selected from one or more of N, N-dimethylformamide, N-dimethylacetamide, acetone, butanone, propylene glycol methyl ether, ethylene glycol ethyl ether, methanol, ethanol, benzene, toluene, p-xylene, tetrahydrofuran, N-methylpyrrolidone and dimethyl sulfoxide.

Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages:

1. the invention discloses a novel resin composition for preparing a low-flow prepreg, which is prepared by introducing a p-hydroxyphenylmaleimide structure with strong polarity and a reactive double bond into a resin system, and experiments prove that: the low-flow-rate prepreg and the soft board polyimide surface prepared by using the resin composition have excellent binding force, excellent heat resistance, toughness and powder dropping property, are very suitable for manufacturing special PCBs (printed circuit boards) such as rigid-flexible combined printed circuit boards, and have very strong processing adaptability and quality reliability;

2. according to the invention, the phenolic resin containing maleimide groups is used as the curing agent of the epoxy resin, and is matched with the epoxy resin curing accelerator, so that the low-flow prepreg with excellent heat resistance, toughness and low powder falling property is obtained, the problem of reduced wettability of a resin system to glass fiber cloth is avoided, and the positive practical significance is obviously achieved;

3. according to the invention, a p-hydroxyphenyl maleimide structure with strong polarity and reactive double bonds is introduced into a resin system, and simultaneously liquid resin containing unsaturated double bonds is introduced, so that the wettability of the no-flow adhesive sheet is obviously improved, and the liquid resin containing unsaturated double bonds can react with the double bonds of maleimide, so that excellent heat resistance is ensured;

4. the preparation process of the low-flow prepreg is simple and easy to implement, has low cost and is suitable for popularization and application.

Detailed Description

The invention is further described below with reference to the following examples:

examples

The chemical structural formula of the phenolic resin containing maleimide groups is as follows:

wherein x and y are integers from 1 to 20, y is an integer from 0 to 20, and n is an integer from 1 to 10. When the ratio of the structural units in the amount of x to y is 1:1, the obtained phenolic resin containing maleimide groups is marked as B-1, the theoretical hydroxyl functional equivalent is 154g/mol, and the theoretical maleimide double bond functional equivalent is 308 g/mol; when the ratio of structural units in the amounts of x and y is 1:5, the theoretical hydroxyl functional equivalent is 122g/mol and the theoretical maleimide double bond functional equivalent is 732 g/mol; the resulting phenolic resin containing maleimide groups is labeled B-2. With reference to the following procedure, a conventional phenol novolac resin, designated B-3, synthesized under the same conditions, had a theoretical hydroxyl functional equivalent of 106 g/mol.

The compound can be synthesized according to the existing synthesis method of thermosetting phenolic resin for electronic materials, and the specific synthesis method can be as follows: putting N- (4-hydroxyphenyl) maleimide, phenol and oxalic acid in required proportion into a flask provided with a thermometer, a condenser and a stirrer, mixing and stirring uniformly, and then placing in a constant temperature water bath at 70 ℃; then, a formaldehyde solution (125mL, phenol/aldehyde ratio 1/0.8) was added dropwise to the flask over 0.5 hour with stirring; after the formaldehyde is added, maintaining the temperature of 70 ℃ and stirring conditions, and reacting for 15 hours; then, the reaction product is dissolved and diluted by 400mL of acetone, and then the reaction product is precipitated by 40% methanol water solution; repeating the dissolving-precipitating operation for 3-5 times, filtering, separating and drying to obtain the pure phenolic resin containing maleimide group shown in the structural formula.

And (2) esterifying phenolic hydroxyl in the maleimide phenolic resin B-1 according to a phenolic hydroxyl esterification method in the prior art to obtain active esterified maleimide-containing resin, wherein the label is B-4, the theoretical ester functional equivalent is 208g/mol, and the theoretical maleimide double-bond functional equivalent is 415 g/mol.

According to the formulations in tables 1 and 2, the maleimide group-containing phenolic resin, epoxy resin curing accelerator, solvent and other components obtained by the above synthesis were uniformly mixed to prepare a resin composition having a solid content of 50%, to obtain examples 1 to 11. And meanwhile, the resin composition glue solutions of comparative examples 1-5 are prepared under the same conditions. Other sources of raw materials in tables 1 and 2 are as follows:

a-1: phosphorus-containing epoxy resin, and peer new materials;

a-2: bisphenol a novolac epoxy resin, mezzanine;

a-3: bisphenol a epoxy resin, national chemical;

a-4: biphenyl epoxy, mezzanine;

b-1: self-made with maleimide phenolic resin;

b-2: self-made with maleimide phenolic resin;

b-3: phenolic resin, self-made;

b-4: self-made polymaleimide active ester;

c-1: imidazole, formed in four countries;

d-1: CTBN, roly-poly;

e-1: butyl acrylate, a home-made reagent;

e-2: allyl bisphenol a, shandongli;

e-3: p-hydroxystyrene, a reagent made in China

F-1: DICY, nabobism;

f-2: DDS (diamino diphenyl sulfone), buxiong north river;

h-1: ball silicon, brocade;

i-1: BMI, sienna bimales;

then, using electronic grade 2116 fiberglass cloth as a reinforcing material to impregnate the resin solution, then heating and curing the prepreg in an oven according to a certain temperature and time program to obtain a low-flow-rubber prepreg, pressing part of the prepreg into a laminated board according to the following conditions, and then evaluating the performances of the prepreg and the laminated board by the following methods. The specific manufacturing conditions of the prepreg and the laminated board are as follows:

prepreg semi-curing conditions: 130 ℃/3-10min +190 ℃/2-10 min; the manufacturing conditions of the plate are as follows: the stacking structure is 1/2OZ Cu +2x2116 bonding sheet +1/2OZ Cu, the thickness of the copper foil is 1OZ, and the thickness of the formed plate is as follows: 0.25mm, the curing condition is that the temperature rises to 3-5 ℃/min, the material temperature is 220 ℃/1-2 h; manufacturing conditions of the PI binding force test plate: the stacking structure is 1/2OZ Cu +25umPI film +1x2116+1/2OZ Cu, the curing condition is that the temperature rises to 3-5 ℃/min, and the material temperature is 220 ℃/1-2 h.

Prepreg test items: glue overflow amount and powder falling rate.

< measurement of glue overflow >: the method comprises the steps of manufacturing PP into a square sample with the size of 100mm x 100mm, punching a round hole with the size of 1 inch in the middle, then overlapping the PP sample together in a stacking mode of 'steel plate + copper-clad plate + PP sample + release film + buffer material + steel plate', using a press with set temperature/pressure/time for pressing, and taking out the glue overflow amount of the round hole position of the sample after pressing is completed so as to evaluate the glue flowing size of the sample under a hot pressing condition.

<Toughness (powder-removing rate)>The determination of (1): the falling degree of the resin powder after the punching/shearing treatment of the prepreg is taken as a judgment basis. The specific test method is that 10cm x10 cm size prepreg 4 pieces are taken, weighed and recorded as m₁. A notch with the depth of 9cm is cut on one side of the sample by a pair of scissors, 29 cutters are cut in total, each sample is made into a small strip with the length of 30 strips and the length of 9cm, and each sample is treated in the same way. The hand-held processed sample was vibrated up and down 30 times with the wrist as the center, and one vibration was recorded back and forth as one vibration. After completion, weigh again and record as m₂Press (m)₁-m₂)/m₁And calculating by 100% to obtain the powder removal rate of the prepreg.

< Heat resistance >: the heat resistance was characterized by the glass transition temperature (Tg) and tested by the DMA method according to the method specified in IPC-TM-6502.4.25.

< PI film peel strength > measurement: and simulating the stacking condition of the rigid-flex board, pressing the low-flow adhesive sheet and the non-adhesive surface of the PI cover film together, and testing the adhesive strength between the low-flow adhesive sheet and the PI cover film by using a universal material testing machine and 90-degree stripping.

< glass fiber cloth wettability > measurement: the laminate was laminated using individual 2116 low flow bond sheets under a set program, and after etching away the copper foil, a 50mmx10mm sample was made and the number of white streaks in the substrate was examined under a wet microscope.

TABLE 1

TABLE 2

As can be seen from the above table, the low flow adhesive bonding sheets prepared by the scheme of the invention have better glass fiber cloth wettability than comparative examples 1-5 and the low flow adhesive bonding sheets of examples 1-11, have better heat resistance and better PI cover film bonding strength than comparative examples 1, 2 and 4, have better PI cover film bonding strength than comparative example 3, and have lower dusting rate than comparative example 5. Therefore, the low-flow adhesive bonding sheet prepared by the scheme of the invention has excellent heat resistance, PI cover film bonding strength, fiberglass cloth wettability and very low powder falling rate.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.