WO2023097771A1 - Epoxy molding compound of modified silicon dioxide grafted epoxy resin, and preparation method therefor - Google Patents

Abstract

An epoxy molding compound of a modified silicon dioxide grafted epoxy resin, and a preparation method therefor. The epoxy molding compound comprises: (A) an epoxy resin; (B) a phenolic resin; (C) an inorganic filler; (D) a silane coupling agent; (E) a release agent; (F) a curing accelerator; (G) a flame-retardant agent; (H) fumed silica; and (I) a coloring agent. The inorganic filler is modified silicon dioxide or a mixture of modified silicon dioxide and unmodified silicon dioxide. The content of the inorganic filler is 60-95 wt% of all epoxy molding compounds. The modified silicon dioxide is silicon dioxide subjected to surface modification of a prepolymer by using polyethylene glycol and diisocyanate under the action of a catalyst. After silicon dioxide is modified, an epoxy resin is grafted on the surface of silicon dioxide by means of a flexible chain, and the obtained epoxy molding compound has the characteristics of high temperature resistance and high toughness, and can be used for packaging various electronic materials.

Description

Epoxy molding compound of modified silicon dioxide grafted epoxy resin and preparation method thereof technical field

The invention relates to an epoxy molding compound of modified silicon dioxide grafted epoxy resin and a preparation method thereof, belonging to the technical field of electronic packaging materials.

Background technique

Epoxy molding compound has high reliability, simple production process, and low production cost. It is widely used in semiconductor devices, integrated circuits, consumer electronics and other fields, and almost occupies the entire microelectronic packaging material market. Epoxy resin contains unique epoxy groups, hydroxyl groups, ether bonds and other active groups, so it has many excellent properties, and can be combined with many curing agents, accelerators, modifiers, etc. to obtain various properties Excellent and distinctive epoxy resin curing systems, adapting to and meeting the requirements of different performance and process performance.

However, due to the high cross-linking density and large internal stress of the cured epoxy resin, when it is filled in the packaging material, there are disadvantages such as brittleness, fatigue resistance, heat resistance, and poor impact toughness. Therefore, improving epoxy resin The performance of materials has attracted much attention. Due to its low thermal expansion coefficient, silica material has excellent properties such as high heat resistance and high humidity resistance, and is widely used as a filler to fill polymers and resin matrices to improve the performance of resin composites.

In view of the lack of toughness of epoxy encapsulation material when silica is used as a filler, this project will prepare the surface grafted epoxy resin to toughen and modify the silica material, and then use it as a filler to prepare a High performance epoxy resin composite encapsulation material.

Contents of the invention

In view of the above technical problems, the present invention provides an epoxy molding compound of modified silicon dioxide grafted epoxy resin, which is used to improve the toughness of silicon dioxide, so that it can be used as a filler for epoxy packaging materials, and improve the performance of electronic packaging materials. properties of composite materials.

In order to achieve the above object, the technical scheme adopted in the present invention is:

A first aspect of the present invention provides a method for surface modification of silicon dioxide, comprising the steps of:

1) Preparation of modified prepolymer:

Stirring and reacting polyethylene glycol and diisocyanate under the action of a catalyst until the concentration of isocyanate in the polymerization reaction system is reduced to 40% to 60% of the initial concentration;

2) Surface modification:

The silicon dioxide and the prepolymer obtained in step 1) are stirred and reacted in a solvent.

As a preferred embodiment, in step 1), the temperature of the stirring reaction is 15-55°C, such as 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C or any temperature in between;

Preferably, the catalyst is selected from dibutyltin dilaurate or dibutyltin didodecylsulfide;

Preferably, the diisocyanate is selected from toluene diisocyanate or diphenylmethane diisocyanate;

Preferably, the polyethylene glycol is polyethylene glycol with a molecular weight of 400-800;

Preferably, in step 1), the mass ratio of the diisocyanate to the polyethylene glycol is 1.5-2.5:1, such as 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2.0:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1 or any mass ratio between them;

Preferably, the mass of the catalyst is 0.05% to 0.5% of the total mass of polyethylene glycol and diisocyanate, such as 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, or any mass percentage between them;

Preferably, step 1) is carried out in an inert gas;

As a preferred embodiment, in step 2), the stirring reaction speed is 1000 to 1500r/min, such as 1000r/min, 1100r/min, 1200r/min, 1300r/min, 1400r/min, 1500r/min or Any rotation speed between them; the temperature of the stirring reaction is 70～90°C, such as 70°C, 75°C, 80°C, 85°C, 90°C or any temperature between them; the time of the stirring reaction is 6～10h;

Preferably, in step 2), the solvent is selected from toluene or toluene cyclohexanone;

Preferably, in step 2), the mass ratio of the silica to the prepolymer is 1:1-3, such as 1:1, 1:2, 1:3 or any mass ratio between them;

Preferably, step 2) is carried out in an inert gas;

Silica nanoparticles absorb water easily and usually have silanol groups on their surface. In the technical scheme of the present invention, the reaction between the prepolymer and silicon dioxide is mainly the reaction of the silanol group on the surface of the silicon dioxide with the flexible chain of the polyethylene glycol prepolymer with isocyanate to make the flexible The chains are branched onto the silica surface.

The second aspect of the present invention provides the modified silica obtained by the above method.

A third aspect of the present invention provides a method of modified silica grafted epoxy resin, comprising the steps of:

Disperse the above-mentioned modified silicon dioxide and epoxy resin in a solvent, pass dimethylamine gas into it, and stir to react.

As a preferred embodiment, the mass ratio of the modified silica to the epoxy resin is 0.35 to 1.5:1, such as 0.35:1, 0.40:1, 0.45:1, 0.50:1, 0.55:1, 0.65 :1, 0.75:1, 0.85:1, 0.95:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1 or any ratio between them.

Preferably, the solvent is a mixed solvent of butyl glycol ether and absolute ethanol, and the volume ratio is preferably 1.8 to 2.2:1;

Preferably, the rotation speed of the stirring reaction is 200-400r/min, the temperature of the stirring reaction is 50-70°C, and the time of the stirring reaction is 2-4 hours;

Preferably, the preparation method further includes post-treatment operations, including suction filtration, washing and drying.

The fourth aspect of the present invention provides a kind of epoxy molding compound of modified silica grafted epoxy resin, and described epoxy molding compound comprises:

(A) epoxy resin;

(B) phenolic resin;

(C) inorganic filler;

(D) silane coupling agent;

(E) release agent;

(F) curing accelerator;

(G) Flame retardants;

(H) fumed silicon;

(1) colorant;

Wherein, the (C) inorganic filler is the above-mentioned modified silica, or a mixture of the above-mentioned modified silica and unmodified silica; the content of the (C) inorganic filler is all epoxy 60-95wt% of the molding compound.

In the technical solution of the present invention, the average particle size of the unmodified silicon dioxide is 5-8 μm, and the modified silicon dioxide is made of unmodified silicon dioxide with an average particle size of 5-8 μm Prepared by modifying the above method.

As a preferred embodiment, the content of each component of the epoxy molding compound is:

The content of (A) epoxy resin is 10-40wt% of the whole epoxy molding compound.

The content of the (B) phenolic resin is 2% to 6wt% of all epoxy molding compounds;

The (D) silane coupling agent is 0.05-5wt% of (C) the inorganic filler;

The (E) release agent is 0.005-2wt% of the entire epoxy molding compound, preferably 0.1-2.5wt%;

The (F) curing accelerator is 0.005-2wt% of the entire epoxy molding compound, preferably 0.01-0.5wt%;

The (G) flame retardant is 0.2 to 0.5 wt% of all epoxy molding compounds;

The (H) fumed silicon is 0.2 to 0.5 wt% of all epoxy molding compounds;

The (I) coloring agent is 0.05～0.3wt% of all epoxy molding compounds;

Preferably, when the inorganic filler is a mixture of the aforementioned modified silica and unmodified silica, the mass ratio of the modified silica to unmodified silica is 0.15˜20:1.

In some specific embodiments, the mass ratio of the modified silica to unmodified silica is 0.15:1, 1:1, 2:1, 3:1, 4:1, 5:1 , 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18 :1, 19:1, 20:1 or any mass ratio between them.

In some specific embodiments, the epoxy resin used as component (A) is a commonly used epoxy resin for encapsulation, and there is no special limitation. Examples include (1) diglycidols such as bisphenol A, bisphenol F, bisphenol S, cresol, xylenol, resorcinol, catechol, alkyl-substituted or unsubstituted diphenols, etc. Glycidyl ether type epoxy resins such as ethers; (2) Novolac type epoxy resins obtained by self-condensation or co-condensation of aldehyde-containing compounds such as formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde, salicylaldehyde, etc. under an acidic catalyst; (3) glycidyl ester type epoxy resin obtained by reacting polyacids such as epoxy resin containing sulfur atom, hydroquinone type epoxy resin, phthalic acid, dimer acid and epichlorohydrin; (4) two Glycidylamine-type epoxy resins obtained by reacting polyamines such as aminodiphenylmethane and isocyanic acid with epichlorohydrin; (5) cyclopentadiene and phenols and/or naphthols co-condensed resins Oxides; (6) epoxy resins containing naphthalene rings; (7) epoxides of arane-type phenol resins such as phenol-arane resins, naphthol-arane resins, etc.; (8) trimethylolpropane-type Epoxy resins; (9) cycloester epoxy resins, etc. These may be used alone or in combination of two or more.

Due to the convenient source of raw materials and low cost, preferably, bisphenol A epoxy resin is used, more preferably epoxy resin represented by general formula (1).

In formula (I), n is the polymerization degree, is the integer of 0～3;

In the general formula (I), the hydrogen atoms on C1～C6 can be replaced by substituents, and the substituents can be substituted or unsubstituted monovalent hydrocarbon groups, which can be saturated or unsaturated; in addition, substituted or unsubstituted The monovalent hydrocarbon group may be linear, branched or cyclic, but is particularly preferably methyl or ethyl.

In the technical solution of the present invention, (B) phenolic resin, as the curing agent of (A) epoxy resin, means monomers, oligomers and polymers with more than two phenolic hydroxyl groups. Its examples include new phenolic phenolic resins represented by formula (II), cresol novolak type epoxy resins, aromatic alkylphenolic resins, trisphenol-based methane type phenolic resins represented by formula (III), naphthol novolac Varnish resins, aralkylphenolic resins and biphenyl novolac resins. The above-mentioned phenolic resins can be used alone or in any combination.

In order to protect the semiconductor chip from moisture, preferably, a low hygroscopicity phenolic resin such as a new phenolic type phenolic resin represented by formula (II) and a trisphenol methane type phenolic resin represented by formula (III) is used.

As a preferred embodiment, the equivalent ratio of (A) epoxy resin and (B) phenolic resin, that is, the ratio of the number of epoxy groups in the epoxy resin to the number of hydroxyl groups in the phenolic resin is not particularly limited, and is To increase the conversion rate of reactants and control the reaction speed, the ratio is preferably set in the range of 0.5-2, more preferably in the range of 0.6-1.3. In order to obtain an epoxy resin molding compound for packaging excellent in moldability and reflow resistance, it is more preferable to set it in the range of 0.8 to 1.0.

In some specific embodiments, (D) the silane coupling agent has the structure shown in the following general formula (IV),

In formula (II), m is an integer of 1 to 3, n is an integer of 0 to 3, and ^R is selected from

any of the

Wherein, (X) _j is selected from any one of a hydrogen atom and an alkyl group with 1 to 6 carbon atoms; R ² and R ³ are each independently selected from methyl or ethyl, and in R ² or OR ³ When there are more than one, they may be the same as or different from each other;

Preferably, R ¹ is

The representative silane coupling agent is mixed into the epoxy molding compound, which can improve the adhesion between the inorganic filler and the resin, and better exert the bulk performance of the filler. Specific examples include γ-anilinopropyltrimethoxysilane, γ-anilinopropyltriethoxysilane, γ-anilinopropylmethyldimethoxysilane, γ-anilinopropylmethyldimethoxysilane, γ-anilinopropylmethyldimethoxysilane, Ethoxysilane, γ-anilinopropylethyldiethoxysilane, γ-anilinopropylethyldimethoxysilane, and the like.

More preferably, the component (D) silane coupling agent is γ-anilinopropyltrimethoxysilane.

In some specific embodiments, the (E) release agent is at least one selected from (α) a linear saturated carboxylic acid with a number average molecular weight of 550-800, and (β) an oxidized polyethylene wax.

Specifically, the structure of the linear saturated carboxylic acid with a number average molecular weight of 550 to 800 is shown in the general formula (V):

Wherein, n is 32-52, but in fact, an appropriate number of repetitions n is selected so that the number-average molecular weight reaches 550-800. Preferably, the number average molecular weight of the linear saturated carboxylic acid is 600 to 800.

In the technical solution of the present invention, considering the hardening properties of the epoxy molding compound, a curing accelerator is further added in the present invention. The (F) curing accelerator is 0.005-2wt% of all epoxy molding compounds. If the amount of curing accelerator is less than 0.005%, the hardening property in a short time tends to deteriorate; once it is higher than 2%, the hardening speed If it is too fast, it is difficult to obtain a good-shaped molded article. In some specific embodiments, the (F) curing accelerator is a substance generally used in epoxy resin molding compounds for packaging, and there is no special limitation on it, and (1) cyclic amidine compounds: 1,8- Diaza-bicyclo[5.4.0]undecene-7, 1,5-diaza-bicyclo[4.3.0]nonene, 5,6-dibutylamino-1,8-di Aza-bicyclo[5.4.0]undecene-7, etc.; (2) quinone compounds: on the basis of cyclic amidine compounds, add maleic anhydride, 1,4-benzoquinone, 2,5 -Quinone compounds such as toluoquinone, 2,3-dimethylbenzoquinone, 2,6-dimethylbenzoquinone, 2,3-dimethoxy-5-methyl-1, etc.; (3) 2- Imidazolines such as methylimidazoline, 2-phenylimidazoline, 2-phenyl-4-methylimidazoline and their derivatives; (4) Organic phosphine: tributylphosphine, methyldiphenylphosphine , triphenylphosphine, tri(4-methylphenyl)phosphine, diphenylphosphine, phenylphosphine, etc.; (5) On the basis of the above-mentioned organic phosphine compounds, maleic anhydride, the above-mentioned quinone A compound having intramolecular polarity formed from a compound having a π-bond such as a compound, benzazomethane, or phenol resin.

In the technical solution of the present invention, the (G) flame retardant is not particularly limited as long as it is an esterified product formed of a compound of phosphoric acid and alcohol or a compound of phosphoric acid and phenol. Examples thereof include trimethyl phosphate, triethyl phosphate, triphenyl phosphate, dihydroxycresyl phosphate, and trixylyl phosphate. Among them, it is preferable to use an aromatic condensed phosphoric acid ester having a structure represented by the general formula (VI) from the viewpoint of hydrolysis resistance.

As a preferred embodiment, the addition amount of the (G) flame retardant is preferably 0.2% to 0.5% relative to all other mixing components except the filler. If it is less than 0.2%, problems such as lead offset, mold cavity, etc. tend to occur. If it exceeds 3%, moldability and moisture resistance will fall.

In the technical solution of the present invention, the (H) fumed silicon is fumed silicon dioxide generally used in epoxy molding compounds for packaging, and there is no particular limitation. Preferably, the average particle size of the fumed silica is in the range of 5-40 nm, and the specific surface area is 360±30 m ² /g. A larger specific surface area and particle size of the silicon dioxide will reduce the toughness of the epoxy molding compound.

The fifth aspect of the present invention provides the preparation method of the above-mentioned epoxy molding compound, comprising the following steps:

(1) Disperse the above-mentioned surface-modified silicon dioxide and epoxy resin in a solvent, feed dimethylamine gas, and stir to react;

(2) After mixing the mixing system obtained in the step (1) with other components in proportion, extruding and kneading to obtain the epoxy molding compound.

As a preferred embodiment, in step (1), the mass ratio of the modified silica to the epoxy resin is 0.35 to 1.5:1;

Preferably, in step (1), the solvent is a mixed solvent of butyl glycol ether and absolute ethanol, and the volume ratio is preferably 1.8 to 2.2:1;

Preferably, in step (1), the rotating speed of the stirring reaction is 200～400r/min, the temperature of the stirring reaction is 50～70°C, and the time of the stirring reaction is 2～4 hours;

Preferably, step (1) also includes post-processing operations, the post-processing includes suction filtration, washing and drying.

As a preferred embodiment, the extrusion mixing temperature in step (2) is 80-120°C.

In the technical solution of the present invention, flexible chain-extended urea is produced by reacting on the surface of silica, and its active end group participates in the epoxy resin network, so that the bonding performance of the interface between the particle and the resin matrix is improved. At the same time, the flexible part of the particle surface can improve the plastic deformation ability of the matrix around the particle, and the local plastic deformation is more likely to occur. These can effectively increase the fracture toughness value of the epoxy molding compound, toughen the epoxy resin matrix, and obviously improve the mechanical properties of the epoxy resin composite material. After the modified silica is mixed with the epoxy resin, the modifier is incorporated into the cross-linked network of the epoxy resin through the active end group of the modified silica, and the modified silica filler is The surface-grafted flexible chains are terminated, thereby grafting the epoxy to the silica surface.

The beneficial effect of the present application is: compared with no modified silica filler, the modified silica powder grafted with epoxy resin on the surface is used as the filler to achieve epoxy The molding compound increases the fracture toughness value of the molding compound while completing high filling, and improves the toughness of the molding compound.

Detailed ways

In order to make the above objects, features and advantages of the present invention more obvious and understandable, specific implementations of the present invention will be described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, the present invention can be implemented in many ways other than those described here, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. The present invention is therefore not limited to the specific implementations specifically disclosed below.

The epoxy resin that following embodiment and comparative example adopt are enumerated as follows:

Bisphenol A epoxy resin represented by formula (VII) (epoxy equivalent: 192, melting point: 105° C., purchased from Nippon Kayaku Co., Ltd., brand name RE410).

The phenolic resins adopted in the following examples and comparative examples are listed as follows:

Phenolic resin 1: new phenolic phenolic resin represented by formula (VIII) (hydroxyl equivalent: 203, softening point: 110°C, purchased from Kolon Chemical Co., Ltd., brand KPH-F3065)

Phenolic resin 2: trisphenol methane type phenolic resin represented by formula (IX) (hydroxyl equivalent: 110, softening point: 97°C, purchased from Meiwa Kasei Co., Ltd., brand name is MEH-7500).

Unmodified silica used in the following examples and comparative examples: silica powder with an average particle diameter of 5-8 μm.

The silane coupling agents used in the following examples and comparative examples are listed as follows: γ-anilinopropyltrimethoxysilane.

The mold release agents used in the following examples and comparative examples are listed as follows: CH ₃ —(CH ₂ ) _n —COOH (n=24 average), Unicid 700 (number average molecular weight: 789) manufactured by Baker Petroleum Company.

The curing accelerator adopted in the following examples and comparative examples is: triphenylphosphine.

The flame retardant adopted in the following examples and comparative examples is: trimethyl phosphate.

The fumed silicon used in the following examples and comparative examples is: silicon dioxide with an average particle size of 15 nm and a specific surface area of 360 m ² /g.

The coloring agent adopted in the following examples and comparative examples is: black organic dye.

Production example of modified silica grafted epoxy resin:

1. Take 2,4-toluene diisocyanate (TDI) and add it to the reaction device, and fill it with nitrogen for 15 minutes. Slowly add polyethylene glycol with a molecular weight of 600 at a rate of 0.5 mL/min. After the dropwise addition was completed, the mixture was heated to 60° C. at a heating rate of 5° C./min at a rotational speed of 1200 r/m, and then continued to heat for 4 hours. Dibutyltin dilaurate was added as a reaction catalyst. The heated sample is subjected to titration detection to detect the content of isocyanate in the reaction system; when the concentration of isocyanate drops to half of the initial concentration, stop heating.

2. Disperse vacuum-dried unmodified silica in anhydrous toluene, and ultrasonically disperse for 0.5 hours. The above-mentioned toluene diisocyanate and polyethylene glycol prepolymer were dissolved in anhydrous toluene, stirred evenly, and mixed with ultrasonically treated silicon dioxide. Under nitrogen protection, the mixture was mechanically stirred at 80° C. at a speed of 1200 r/min for 8 hours. Repeated washing with anhydrous toluene to remove the unreacted polyethylene glycol prepolymer, and vacuum drying the obtained product at 60° C. for 12 hours to obtain modified silicon dioxide powder.

3. Mix 10 mL of ethylene glycol butyl ether with 5 mL of absolute ethanol, dissolve the above-mentioned modified silica powder and epoxy resin in it, and heat to 60°C. Under the condition of mechanical stirring at 300 r/min, dimethylamine gas was introduced to react for 3 hours. After the reaction, the mixture was suction filtered, washed, and vacuum-dried at 60° C. for 12 hours. The product was white or light yellow powder, and epoxy resin-grafted modified silica was obtained.

Wherein, in embodiment 1-9, the quality of diisocyanate, polyethylene glycol, dibutyltin dilaurate in step 1, the unmodified silicon dioxide used in step 2 and the epoxy resin in step 3 See Table 1 for the quantity.

Table 1

In step 1, the method for determining the concentration of isocyanate is as follows: weigh about 1 g of the sample, place it in a 100 mL Erlenmeyer flask, and add 10 mL of dioxane. After dissolving, use a pipette to accurately transfer 10 mL of 0.5 mol/L n-butylamine dioxane solution, let it stand for 15 minutes, and then drop 3 to 5 drops of methyl red solution. Titrate with 0.1mol/L hydrochloric acid standard solution, the solution turns from yellow to red at the end point, and perform blank titration at the same time.

The calculation formula of isocyanate concentration is as shown in formula (VIII):

In the formula (VIII): C is the percentage of isocyanate in the sample;

V is the volume (mL) of consumed hydrochloric acid standard solution in sample titration;

_V is the volume (mL) of consumed hydrochloric acid standard solution in the blank titration;

M is the concentration (mol/L) of hydrochloric acid standard solution;

W is the weight (g) of the sample.

The modified silicon dioxide of gained surface graft epoxy resin is applied in the following examples:

Example 1

With the modified silica of 94.44g grafted epoxy resin (wherein epoxy resin 38.6g, silicon dioxide 19.3g), the phenolic resin 1 of 2.78g, the phenolic resin 2 of 1.19g, the curing accelerator of 0.28g, 0.41g of flame retardant, 0.15g of silane coupling agent, 0.25g of mold release agent, 0.3g of fumed silicon and 0.2g of coloring agent are mixed, kneaded and kneaded at an extrusion temperature of 100°C, Cooling, finely crushing, and finally an epoxy molding compound is obtained.

Example 2

89.44g of modified silica grafted with epoxy resin, including 35.6g of epoxy resin, 17.8g of silica, 5g of unmodified silica, 2.78g of phenolic resin 1, and 1.19g of phenolic resin 2 , 0.28g of curing accelerator, 0.41g of flame retardant, 0.15g of silane coupling agent, 0.25g of release agent, 0.3g of fumed silicon and 0.2g of colorant are mixed at an extrusion temperature of 100°C Kneading and kneading, cooling, and fine grinding are carried out under certain conditions, and finally an epoxy molding compound is obtained.

Example 3

84.44g of modified silica grafted with epoxy resin, including 32.6g of epoxy resin, 16.3g of silica, 10g of unmodified silica, 2.78g of phenolic resin 1, and 1.19g of phenolic resin 2 , 0.28g of curing accelerator, 0.41g of flame retardant, 0.15g of silane coupling agent, 0.25g of release agent, 0.3g of fumed silicon and 0.2g of colorant are mixed at an extrusion temperature of 100°C Kneading and kneading, cooling, and fine grinding are carried out under certain conditions, and finally an epoxy molding compound is obtained.

Example 4

74.44g of modified silica grafted with epoxy resin, including 29.6g of epoxy resin, 14.8g of silica, 20g of unmodified silica, 2.78g of phenolic resin 1, and 1.19g of phenolic resin 2 , 0.28g of curing accelerator, 0.41g of flame retardant, 0.15g of silane coupling agent, 0.25g of release agent, 0.3g of fumed silicon and 0.2g of colorant are mixed at an extrusion temperature of 100°C Kneading and kneading, cooling, and fine grinding are carried out under certain conditions, and finally an epoxy molding compound is obtained.

Example 5

64.44g of modified silica grafted with epoxy resin, including 26.6g of epoxy resin, 13.3g of silica, 30g of unmodified silica, 2.78g of phenolic resin 1, and 1.19g of phenolic resin 2 , 0.28g of curing accelerator, 0.41g of flame retardant, 0.15g of silane coupling agent, 0.25g of release agent, 0.3g of fumed silicon and 0.2g of colorant are mixed at an extrusion temperature of 100°C Kneading and kneading, cooling, and fine grinding are carried out under certain conditions, and finally an epoxy molding compound is obtained.

Example 6

54.44g of modified silica grafted with epoxy resin, including 23.6g of epoxy resin, 11.8g of silica, 40g of unmodified silica, 2.78g of phenolic resin 1, and 1.19g of phenolic resin 2 , 0.28g of curing accelerator, 0.41g of flame retardant, 0.15g of silane coupling agent, 0.25g of release agent, 0.3g of fumed silicon and 0.2g of colorant are mixed at an extrusion temperature of 100°C Kneading and kneading, cooling, and fine grinding are carried out under certain conditions, and finally an epoxy molding compound is obtained.

Example 7

44.44g of modified silica grafted with epoxy resin, including 20.6g of epoxy resin, 10.3g of silica, 50g of unmodified silica, 2.78g of phenolic resin 1, and 1.19g of phenolic resin 2 , 0.28g of curing accelerator, 0.41g of flame retardant, 0.15g of silane coupling agent, 0.25g of release agent, 0.3g of fumed silicon and 0.2g of colorant are mixed at an extrusion temperature of 100°C Kneading and kneading, cooling, and fine grinding are carried out under certain conditions, and finally an epoxy molding compound is obtained.

Example 8

34.44g of modified silica grafted with epoxy resin, including 17.6g of epoxy resin, 8.8g of silica, 60g of unmodified silica, 2.78g of phenolic resin 1, and 1.19g of phenolic resin 2 , 0.28g of curing accelerator, 0.41g of flame retardant, 0.15g of silane coupling agent, 0.25g of release agent, 0.3g of fumed silicon and 0.2g of colorant are mixed at an extrusion temperature of 100°C Kneading and kneading, cooling, and fine grinding are carried out under certain conditions, and finally an epoxy molding compound is obtained.

Example 9

24.44g of modified silica grafted with epoxy resin, including 14.6g of epoxy resin, 7.3g of silica, 80g of unmodified silica, 2.78g of phenolic resin 1, and 1.19g of phenolic resin 2 , 0.28g of curing accelerator, 0.41g of flame retardant, 0.15g of silane coupling agent, 0.25g of release agent, 0.3g of fumed silicon and 0.2g of colorant are mixed at an extrusion temperature of 100°C Kneading and kneading, cooling, and fine grinding are carried out under certain conditions, and finally an epoxy molding compound is obtained.

Comparative example 1

94.44g of unmodified silica, 2.78g of phenolic resin 1, 1.19g of phenolic resin 2, 0.28g of curing accelerator, 0.41g of flame retardant, 0.15g of silane coupling agent, 0.25g of Release agent, 0.3g of fumed silicon and 0.2g of coloring agent are mixed, kneaded and kneaded, cooled, and finely pulverized under the condition of extrusion temperature of 100°C, and finally an epoxy molding compound is obtained.

The content of each composition of above embodiment is performance test as shown in table 2-1 and table 2-2:

table 2-1

the	Example 1	Example 2	Example 3	Example 4	Example 5
Phenolic resin 1	2.78	2.78	2.78	2.78	2.78

Phenolic resin 2	1.19	1.19	1.19	1.19	1.19
Colorant	0.2	0.2	0.2	0.2	0.2
Modified silica grafted with epoxy resin	94.44	89.44	84.44	74.44	64.44
Unmodified silica	the	5	10	20	30
A silane coupling agent	0.15	0.15	0.15	0.15	0.15
curing accelerator	0.28	0.28	0.28	0.28	0.28
flame retardant	0.41	0.41	0.41	0.41	0.41
Release agent	0.25	0.25	0.25	0.25	0.25
fumed silicon	0.3	0.3	0.3	0.3	0.3
Spiral flow length (cm)	105	104	99	93	89
Gelation time (s)	25	30	26	28	30
Viscosity(Pa.s)	33	32	36	38	43
Warpage	★★★	★★★	★★★	★★	★★
Dielectric constant/ε	1.7	1.8	2.1	2.5	2.9
Dielectric loss tangent/tanδ	0.003	0.004	0.006	0.008	0.01
Fracture toughness (MPa)	11.51	11.37	11.25	11.10	10.73

Table 2-2

the	Example 6	Example 7	Example 8	Example 9	Comparative example 1
Phenolic resin 1	2.78	2.78	2.78	2.78	2.78
Phenolic resin 2	1.19	1.19	1.19	1.19	1.19
Colorant	0.2	0.2	0.2	0.2	0.2
Modified silica grafted with epoxy resin	54.44	44.44	34.44	24.44	the
Unmodified silica	40	50	60	70	94.44
A silane coupling agent	0.15	0.15	0.15	0.15	0.15
curing accelerator	0.28	0.28	0.28	0.28	0.28
flame retardant	0.41	0.41	0.41	0.41	0.41
Release agent	0.25	0.25	0.25	0.25	0.25
fumed silicon	0.3	0.3	0.3	0.3	0.3
Spiral flow length (cm)	105	104	99	93	89

Gelation time (s)	25	30	26	28	30
Viscosity(Pa.s)	33	32	36	38	43
Warpage	★★★	★★★	★★★	★★	★★
Dielectric constant/ε	1.7	1.8	2.1	2.5	2.9
Dielectric loss tangent/tanδ	0.003	0.004	0.006	0.008	0.01
Fracture toughness (MPa)	10.42	9.87	9.56	9.47	9.15

It can be seen from Table 2-1 and Table 2-2 that, compared with Comparative Example 1 without adding modified silica, in Example 1-9, the epoxy molding compound with modified silica was added in the Keeping other parameters basically unchanged, the connection between silica and resin is better, it is not easy to be brittle, the fracture toughness value increases, and the toughness is improved.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent transformations made using the content of the description of the present invention, or directly or indirectly used in other related technical fields, are all included in the same principle. Within the scope of patent protection of the present invention.

Claims (10)

1. The surface modification method of silica, is characterized in that, comprises the steps:

   1) Preparation of modified prepolymer:

   Stirring and reacting polyethylene glycol and diisocyanate under the action of a catalyst until the concentration of isocyanate in the polymerization reaction system is reduced to 40% to 60% of the initial concentration;

   2) Surface modification:

   The silica and the prepolymer obtained in step 1) are stirred and reacted in a solvent.
2. The surface modification method of silica according to claim 1, characterized in that, in step 1), the temperature of the stirring reaction is 15-55°C;

   Preferably, the catalyst is selected from dibutyltin dilaurate or dibutyltin didodecylsulfide;

   Preferably, the diisocyanate is selected from toluene diisocyanate or diphenylmethane diisocyanate;

   Preferably, the polyethylene glycol is polyethylene glycol with a molecular weight of 400-800;

   Preferably, in step 1), the mass ratio of the diisocyanate to the polyethylene glycol is 1.5-2.5:1;

   Preferably, the mass of the catalyst is 0.05% to 0.5% of the total mass of polyethylene glycol and diisocyanate;

   Preferably, step 1) is performed in an inert gas.
3. The surface modification method of silica according to claim 1, characterized in that, in step 2), the rotational speed of the stirring reaction is 1000-1500r/min; the temperature of the stirring reaction is 70-90°C The time of said stirring reaction is 6～10 hours;

   Preferably, the solvent is selected from any one of toluene and cyclohexanone;

   Preferably, the mass ratio of the silica to the prepolymer is 1:1-3;

   Preferably, step 2) is performed in an inert gas.
4. The modified silicon dioxide obtained by the method according to any one of claims 1-3.
5. The method for modified silicon dioxide grafted epoxy resin, is characterized in that, comprises the steps:

   Disperse the modified silicon dioxide and epoxy resin according to claim 4 in a solvent, feed dimethylamine gas, and stir to react.
6. method according to claim 5, is characterized in that, the mass ratio of described modified silica and epoxy resin is 0.35～1.5:1;

   Preferably, the solvent is a mixed solvent of butyl glycol ether and absolute ethanol, and the volume ratio is preferably 1.8 to 2.2:1;

   Preferably, the rotation speed of the stirring reaction is 200-400r/min, the temperature of the stirring reaction is 50-70°C, and the time of the stirring reaction is 2-4 hours;

   Preferably, the preparation method further includes post-treatment operations, including suction filtration, washing and drying.
7. The epoxy molding compound of modified silicon dioxide grafted epoxy resin, is characterized in that, described epoxy molding compound comprises:

   (A) epoxy resin;

   (B) phenolic resin;

   (C) inorganic filler;

   (D) silane coupling agent;

   (E) release agent;

   (F) curing accelerator;

   (G) Flame retardants;

   (H) fumed silicon;

   (1) colorant;

   Wherein, the (C) inorganic filler is the modified silica according to claim 4, or a mixture of the modified silica and unmodified silica according to claim 4; the (C) ) The content of the inorganic filler is 60-95wt% of the total epoxy molding compound.
8. The epoxy molding compound according to claim 7, wherein the content of each component of the epoxy molding compound is:

   The content of (A) epoxy resin is 10-40wt% of all epoxy molding compounds;

   The content of the (B) phenolic resin is 2% to 6wt% of all epoxy molding compounds;

   The (D) silane coupling agent is 0.05-5wt% of (C) the inorganic filler;

   The (E) release agent is 0.005-2wt% of the entire epoxy molding compound, preferably 0.1-2.5wt%;

   The (F) curing accelerator is 0.005-2wt% of the entire epoxy molding compound, preferably 0.01-0.5wt%;

   The (G) flame retardant is 0.2 to 0.5 wt% of all epoxy molding compounds;

   The (H) fumed silicon is 0.2% to 0.5wt% of all epoxy molding compounds;

   The (I) coloring agent is 0.05～0.3wt% of all epoxy molding compounds;

   Preferably, when the inorganic filler is a mixture of the modified silica and unmodified silica according to claim 4, the mass ratio of the modified silica to the unmodified silica is 0.15～ 20:1.
9. The preparation method of the epoxy molding compound described in any one of claims 6-7, is characterized in that, comprises the steps:

   (1) the modified silicon dioxide and epoxy resin described in claim 4 are dispersed in a solvent, and dimethylamine gas is passed into, and stirred for reaction;

   (2) After mixing the mixing system obtained in the step (1) with other components in proportion, extruding and kneading to obtain the epoxy molding compound.
10. The preparation method according to claim 9, characterized in that, in step (1), the mass ratio of the modified silica to the epoxy resin is 0.35 to 1.5:1;

    Preferably, in step (1), the solvent is a mixed solvent of butyl glycol ether and absolute ethanol, and the volume ratio is preferably 1.8 to 2.2:1;

    Preferably, in step (1), the rotational speed of the stirring reaction is 200-400r/min, the temperature of the stirring reaction is 50-70°C, and the time of the stirring reaction is 2-4 hours;

    Preferably, step (1) also includes post-processing operations, the post-processing comprising suction filtration, washing and drying;

    Preferably, the extruding and kneading temperature in step (2) is 80-120°C.