JPH0925334A - Epoxy resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin composition improved in storage stability, moldability, etc., by mixing an epoxy resin with a curing agent, a cure accelerator comprising a specified organophosphorus compound, a filler, etc. SOLUTION: This epoxy resin composition consists essentially of an epoxy resin (e.g. biphenyl epoxy resin), a curing agent (e.g. phenol novolac resin), a cure accelerator comprising an organophosphorus compound represented by the formula (wherein X is a quat. phosphonium ion; R is a 1-4C alkyl or alkoxyl; and (n) is 1 or 2) and a filler (e.g. alumina) or a fibrous reinforcement (e.g. glass fiber). Examples of the compounds of the formula include tetraphenylphosphonium tetra(methyl phenyl)borate and tetraphenylphosphonium tetra(propylphenyl)borate. This composition is desirable as a material for laminates or a material for sealing electronic components.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition suitable for sealing laminated plates, electronic parts and the like, and more particularly to a low hygroscopic epoxy resin composition having excellent storage stability and moldability.

[0002]

2. Description of the Related Art Epoxy resin has been widely used as an insulating material, a coating material, a sealing material, a laminated material, and a prepreg material in the fields of electric equipment, electronic parts, etc.
The requirements for its performance are becoming more and more severe.

In particular, electronic devices are required to be compact and lightweight, have high performance, and the like, and therefore, high-density mounting of semiconductor parts used therein is strongly demanded, and recently, surface-mounting type semiconductors suitable for high-density mounting are mainstream. There is.
Further, the package is becoming smaller and thinner year by year, and a thin package with a thickness of 1 mm has already been put into practical use, and recently, a package with a thickness of 0.5 mm or less has been developed. As a part of measures for improving the mounting density, (1) a surface mounting method in which components are soldered on the surface of the substrate, (2) a method for mounting electronic components on a printed circuit board, etc. have been proposed. In particular, the surface mounting method has a package temperature of 200 ° C or higher during mounting.
When a large amount of water is present in the package, it is rapidly vaporized and its volume expands, and the vapor pressure thereof causes the interface between the chip and the sealing material to peel off or the package to break. All of these impair the reliability of the device. However, conventional resin compositions containing a resin, a curing agent, a curing accelerator, etc. cannot fully meet the above needs. Therefore, investigations have been made on increasing the glass transition temperature of the encapsulating material, reducing the moisture absorption rate, improving the adhesive force, or a latent curing accelerator. In particular, in a thin semiconductor package, lower moisture absorption and higher adhesion of the sealing material are effective. Specifically, an epoxy resin composition (JP-A-3-207714, JP-A-4-48759) comprising an epoxy resin having a biphenyl skeleton and a phenol aralkyl resin curing agent is used as a sealing resin, or a naphthalene skeleton is used. Low hygroscopic epoxy resin composition having
4-50223, JP-A-4-199856, JP-A-4-19
Japanese Patent No. 9857) is disclosed.

In particular, as a method of sealing electronic components of semiconductors, multipot molding in which the molding machine is automated and runners, sprues, etc. which are unnecessary after molding are reduced as much as possible for the purpose of cost reduction of the sealing material and improvement of mass productivity. Is being done.
In the multi-pot method in which the sealing material is used as a mini tablet, a sealing material having excellent moisture resistance and pot life is required.

Further, the laminated plate is used for mounting electronic parts and the like, but it is often used under open air, and reliability deteriorates when electric characteristics deteriorate due to moisture absorption. Therefore, a material having a small moisture absorption rate and no change in electrical characteristics is desired. In addition, since the board is exposed to high temperatures when electronic components are mounted on the board or when it is heat-bonded, it becomes impossible to mount the parts if swelling or peeling occurs, or even if it can be mounted, the reliability will drop significantly. Come here. As measures against these, for example, an aromatic polyimide ether composition (JP-A-64-65133), a composition containing a cyclic phosphonitrile compound and an aromatic maleimide compound, etc.
Japanese Patent Laid-Open No. 1-143427) and the like are disclosed.

[0006]

However, in the above-mentioned prior art, for example, when applied to a sealing material for a semiconductor device,
Although it has a considerable effect of preventing the occurrence of package cracks during solder reflow, there are problems that the curability is significantly reduced when the sealing resin absorbs moisture during storage, and the fluidity is significantly reduced due to an increase in melt viscosity. There is a problem that it cannot be put to practical use unless the quality of the stopping material and the storage conditions are strictly controlled.

Similarly, when the above-mentioned conventional technique is applied to a laminated plate, there are problems in moisture absorption rate and storage stability of the impregnating varnish.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an epoxy resin composition having excellent storage stability, moldability, high adhesive strength and low hygroscopicity. That is.

[0009]

In order to solve the above-mentioned problems, the inventors of the present invention have been able to solve the above-mentioned problems by influencing the properties such as a hardening accelerator, glass fiber, glass cloth, filler, coupling agent, release agent, etc. The inventors thoroughly studied the mixing conditions of the raw materials and the molding conditions. As a result, they have found that the above problems can be dramatically improved by using a specific curing accelerator, and have completed the present invention. The gist of the present invention is as follows.

In the composition containing an epoxy resin, a curing agent and a curing accelerator as essential components, the curing accelerator has the general formula (1)

[0011]

Embedded image

(Wherein X is a quaternary phosphonium ion,
R is a C1-C4 alkyl group and an alkoxy group, n is 1
2 to 2. ) An epoxy resin composition comprising an organic phosphorus compound represented by

The curing accelerator represented by the general formula (1) is a quaternary phosphonium tetra-substituted phenyl borate. Specifically, tetraphenylphosphonium tetra (methylphenyl) borate, tetraphenylphosphonium tetra (ethylphenyl) borate, tetraphenylphosphonium tetra (propylphenyl) borate, tetraphenylphosphonium tetra (butylphenyl) borate, tetraphenyl Phosphonium tetra (methoxyphenyl) borate, tetraphenylphosphonium tetra (ethoxyphenyl) borate, tetraphenylphosphonium tetra (propoxyphenyl) borate, tetraphenylphosphonium tetra (butoxyphenyl) borate, tetraphenylphosphonium tetra (2,2 4-dimethylphenyl) borate, tetraphenylphosphonium tetra (3,5-dimethoxyphenyl) borate, Scan (4-methylphenyl) phenyl phosphonium tetra (methylphenyl) borate, Buchirutorisu (3-methylphenyl) phosphonium tetra (methylphenyl) is borate. Two or more kinds of these curing accelerators can be used in combination, if necessary. Further, it may be used in combination with a known curing accelerator, if necessary. The above curing accelerator can be used in exactly the same manner as a usual curing accelerator. Moreover, it can be used after being heated and melted with the curing agent at 100 ° C. or higher in advance, if necessary. The curing accelerator is added in an amount of 1 to 50 mmol, preferably 3 to 30 mmol, based on 100 parts by weight of the epoxy resin.

Known epoxy resins can be used in the present invention. For example, glycidyl ethers of phenols such as bisphenol A, bisphenol F, resorcinol, phenol novolac, cresol novolac, glycidyl ethers of alcohols such as butanediol, polyethylene glycol, polypropylene glycol, phthalic acid, isophthalic acid, tetrahydrophthalic acid, etc. Glycidyl ester of carvone,
Glycidyl-type (including methylglycidyl-type) epoxy resins such as those in which the active hydrogen bonded to the nitrogen atom of aniline, isocyanuric acid, etc. is replaced by a glycidyl group, vinylcyclohexene diepoxide obtained by epoxidizing the olefin bond in the molecule , 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 2- (3,4-epoxy) cyclohexyl-
5,5-spiro (3,4-epoxy) cyclohexane-
So-called alicyclic epoxy resin such as m-dioxane, biphenyl type epoxy resin, polyfunctional epoxy resin having a naphthalene skeleton, dicyclopentadiene type epoxy resin,
A halogenated phenol novolac type epoxy resin or the like is used. Of these epoxy resins, the most suitable is
The general formula (2)

[0015]

Embedded image

(Wherein R represents a hydrogen atom or a methyl group and may be different from each other; n represents an integer of 0 to 2), that is, two or more epoxies per molecule. Biphenyl type epoxy resin having a group and a biphenyl skeleton, or a general formula (4)

[0017]

[Chemical 6]

(Wherein n = 1 to 2) a dicyclopentadiene type epoxy resin represented by the general formula (5)

[0019]

Embedded image

Alternatively, the general formula (6)

[0021]

Embedded image

Alternatively, the general formula (7)

[0023]

Embedded image

There are naphthalene type epoxy resins represented by the formula (n = 1 to 10). Moreover, two or more of these epoxy resins can be used in combination with other epoxy resins, if necessary.

The curing agent used in the present invention is not particularly limited, and known curing agents can be used. For example,
Novolaks obtained by condensing phenol, cresol, xylenol, etc. and formaldehyde, etc. with an acidic catalyst, polycondensates of phenol / aralkyl ethers, dicyclopentadiene compounds, compounds having a naphthalene skeleton, polymers of alkenylphenols, etc. is there. Among them, a particularly preferable curing agent is represented by the general formula (3).

[0026]

Embedded image

(In the formula, m represents an integer of 1 to 10) having a polycondensation product of a phenol and an aralkyl ether, a dicyclopentadiene skeleton or a naphthalene skeleton, and at least two per molecule. There are compounds having a hydroxyl group. Two or more of these curing agents can be used in combination with other curing agents, if necessary. These curing agents are added in an amount of 0.5 to 1.5 equivalents, preferably 0.8 to 1.2 equivalents, based on the epoxy resin. If it is less than 0.5 equivalent, the curing of the epoxy resin will be insufficient and the cured product will be inferior in heat resistance, moisture resistance and electrical properties. On the other hand, if it exceeds 1.5 equivalents, the curing agent component becomes excessive and a large amount of phenolic hydroxyl groups remain in the cured resin, resulting in poor electrical properties and moisture resistance. As the above-mentioned curing agent, within a range not impairing the object of the present invention, 70% by weight or less of another curing agent is used together with a condensate of phenols and aldehydes such as phenol novolac resin. You can also

If necessary, an inorganic filler can be added to the epoxy resin composition of the present invention. For example, fused silica, crystalline silica, alumina, calcium carbonate, zirconium silicate, calcium silicate, talc, clay,
Mica or the like can be used. The inorganic filler is preferably blended in an amount of 50 to 90% by volume with respect to the entire resin composition. These inorganic fillers are added for the purpose of improving the thermal expansion coefficient, thermal conductivity, elastic modulus, etc. of the cured product, and if the blending amount is less than 50% by volume, these characteristics cannot be sufficiently improved, and If it exceeds 90% by volume, the viscosity of the resin composition remarkably increases and the fluidity decreases, making molding difficult. The average particle size of the inorganic filler is particularly preferably in the range of 0.1 to 50 μm. If it is less than 0.1 μm, the viscosity of the resin composition will increase, and if it exceeds 50 μm, the resin component and the filler will be easily separated from each other, and the cured product will become nonuniform or the properties of the cured product will vary. Fillability into narrow gaps is reduced. For example, when the filler is blended in an amount of 75% by volume or more, it is preferable that the filler particles have a spherical shape rather than a square shape and that the particle size distribution is in a wide range of 0.1 to 100 μm. Since such a filler easily has a close-packed structure, the viscosity of the material does not increase even if the compounding amount is increased,
It is possible to obtain a composition having excellent fluidity.

In order to apply the epoxy resin composition of the present invention to a laminate, a glass cloth is impregnated with the epoxy resin composition and then pre-cured (B-staged) to prepare a prepreg. A laminated board can be obtained by laminating and adhering a plurality of prepregs as needed. At this time, as the epoxy resin composition, it is possible to use the one in which the above-mentioned filler is blended in addition to the fibrous base material. With this laminate, a laminate having a smaller coefficient of thermal expansion than an ordinary laminate can be obtained.

In the present invention, a flexibilizing agent or the like for strengthening the resin cured product or lowering the elastic modulus can be used if necessary. As the flexibilizer, those which are incompatible or partially compatible with the epoxy resin and the curing agent can lower the elasticity of the cured product without lowering the glass transition temperature so much that the butadiene / acrylonitrile copolymer or A butadiene-based flexibilizing agent such as a modified copolymer having an amino group, an epoxy group or a carboxyl group at its terminal or side chain, an acrylonitrile-butadiene-styrene copolymer, or an amino group or a hydroxyl group at the terminal or side chain, A modified silicone-based elastomer having an epoxy group, a carboxyl group, or the like is used, and the silicone-based flexibilizing agent is particularly effective in terms of moisture resistance and purity. The blending amount of the flexibilizer is 2 to 2 with respect to the total resin composition.
0% by weight is preferred. If the blending amount is less than 2% by weight, there is almost no effect on the toughness and low elastic modulus of the cured product. Also,
When it exceeds 20% by weight, the fluidity of the resin composition and the mechanical strength at high temperature are remarkably lowered, and the flexibilizing agent is raised on the surface of the cured resin product, so that the molding die becomes significantly soiled.

In addition to the above, the resin composition of the present invention may optionally contain a coupling agent for enhancing the adhesiveness between the resin component and the glass fiber, glass cloth or inorganic filler.
Known compounds such as various silane compounds, titanium compounds, aluminum chelates, and aluminum / zirconium compounds can be used. Further, known compounds such as carnauba wax, montanic acid wax, and polyalkylene wax can be used as the release agent. Known compounds such as carbon black, titanium oxide, red lead and red iron oxide can be used as the colorant.

[0032]

The epoxy resin composition of the present invention exhibits excellent storage stability because the organophosphorus compound used as the curing accelerator does not react much at around room temperature and shows a rapid curing reaction at 100 ° C. or higher. This is because it has the property of showing acceleration.
Another reason is that the activity of promoting the curing reaction hardly changes even when the material absorbs moisture during storage.

Further, the resin composition of the present invention shows good moldability with little generation of voids at the time of molding, because the low molecular weight component and the curing accelerator contained in the epoxy resin or the curing agent component are relatively low in temperature. It is considered that this is because it has the effect of selectively reacting and reducing volatile components generated when the resin is cured. In particular, when the curing accelerator is used by heating and dissolving it with the curing agent at a temperature of 100 ° C. or higher in advance, it is considered that the voids can be further reduced because the above effect is more remarkably exhibited.

Next, when the biphenyl type epoxy resin, dicyclopentadiene type epoxy resin and naphthalene type epoxy resin are used in the epoxy resin composition of the present invention, the reason why they show particularly low hygroscopicity is that the conventional resin system is used. The molecular packing is dense because it has a hydrophobic structure in terms of chemical structure and the cured product has a high density.
It is considered that the formed network structure is less likely to allow water to permeate, or the concentration of hydroxyl groups contained per unit volume is low. Further, it is considered that the reason why the adhesive strength is similarly high is that the residual stress generated in the cured resin is small due to the low glass transition temperature of the cured product and the high flexibility of the resin. Particularly, in the epoxy resin composition of the present invention, it is considered that such characteristics are exhibited because the curing accelerator used in the present invention has a large effect of making the molecular packing dense and increasing the flexibility of the resin. . In addition, it is considered that the curing accelerator has a latent reaction accelerating property, so that the melt viscosity of the resin composition becomes low and the wettability of the resin composition with respect to the adherend is good.

It was totally unexpected that the curing accelerator of the present invention had such excellent effects.

[0036]

EXAMPLES The present invention will be described more specifically below with reference to examples.

[Examples 1 to 4 and Comparative Examples 1 to 3] Table 1 shows the names and abbreviations of the curing accelerators used in Examples and Comparative Examples.

[0038]

[Table 1]

[0039]

[Table 2]

The epoxy resin composition shown in Table 2 was used in an amount of about 60-
The mixture was melt-kneaded with a twin-screw roll heated to 100 ° C. for about 10 minutes, then cooled and pulverized to obtain a target sealing material. The thus obtained sealing material was transfer-molded under the conditions of 180 ° C., 70 kg / cm ² , and 90 seconds, and the moldability immediately after the production of the sealing material and various characteristics of the molded product were measured. The results are shown in Table 3.

[0041]

[Table 3]

In the table, the melt viscosity is a mold nozzle of an elevation type flow tester heated to 180 ° C. (inner diameter 1 mmφ × 10 mm)
From the maximum flow rate when 2 g of the sealing material was extruded with a load of 10 kg, it was calculated.

The spiral flow is the length of the molded product when the spiral flow measuring mold defined in EMMI-1-66 is sandwiched between the upper and lower hot plates of the transfer molding machine and 20 g of the sealing material is molded under the above conditions. It was evaluated by.

The hot hardness was measured by a Barcol hardness meter immediately after the molding die was opened by transfer molding of a disc having a diameter of 20 mmφ and the hot hardness of the disc.

The internal voids of the molded product were evaluated by observing the disc having a diameter of 20 mmφ with a soft X-ray fluoroscope.

The saturated moisture absorption rate is obtained by placing a disc having a diameter of 90 mm and a thickness of 2 mm in a double pressure vessel made of polytetrafluoroethylene-SUS and absorbing moisture in an atmosphere of 60 ° C./100% RH for 240 hours. The moisture absorption rate of was determined.

[0047]

[Table 4]

Table 4 shows each sealing material at 40 ° C./20% RH.
And changes over time in fluidity (spiral flow) and curability (hardness during heat) when stored at 40 ° C./85% RH for 7 days, respectively.

From Table 3, the encapsulating material of this example has excellent moldability (fluidity, curability and burrs), has less voids in the molded product, and has low hygroscopicity and high adhesiveness. I understand.

Further, from Table 4, the sealing material of the comparative example is 40
When stored at ℃ / 20% RH, the fluidity decreases,
When stored under high humidity conditions of 40 ° C./85% RH, the hardness when hot is drastically reduced. However, it can be seen that the sealing material of the present application has a small change in fluidity and curability and is excellent in storage stability.

Next, the amount of free halogen extracted from the molded product was measured. First, the sealing material is 180 ℃, 70kg /
Transfer molding under the condition of cm ² for 90 seconds, diameter 90
A disk of mmφ × 2 mm in thickness was obtained. The disc was heat-treated in a thermostat at 180 ° C. for a predetermined time and then pulverized by a mill pulverizer TI-100 type (manufactured by HEIKO). 5 g of the fine powder was put together with 50 ml of pure water in a polytetrafluoroethylene-SUS double pressure vessel and heated at 120 ° C. for 300 hours. The free halogen ions extracted in pure water were measured with an ion chromatograph type 10 (manufactured by Dionex). Table 5 shows the results.

[0052]

[Table 5]

Example 5 As an epoxy resin, 60 parts by weight of a biphenyl type epoxy resin (epoxy equivalent 188), a naphthalene type epoxy resin (epoxy equivalent 22)
1), 10 parts by weight of brominated bisphenol type epoxy resin (epoxy equivalent 375), phenol aralkyl resin (hydroxyl equivalent 170), tetraphenylphosphonium tetra (methylphenyl) borate 6 as a curing accelerator
Parts by weight, 10 parts by weight of polydimethylsiloxane having an amino group at the end and having a molecular weight of about 30,000 as a flexibilizer, and 10 parts by weight of epoxysilane as a coupling agent are dissolved in methyl ethyl ketone, and the solution viscosity at 23 ° C. is 20.
Adjusted to be ~ 100 poise. This is thickness 50
A plain weave E glass cloth of μm was dipped to obtain a glass cloth impregnated with 45% by weight of resin. 7 pieces of this glass cloth and copper foil on top of it
A laminate was obtained by heat-press molding for 60 minutes / cm ² . The bending strength and the peel strength of the copper foil before and after boiling of the obtained laminated plate were measured according to JIS-C-6481. Table 6 shows the results.

[0054]

[Table 6]

Comparative Example 4 The same procedure as in Example 5 was carried out except that 1,8-diazabicyclo- (5,4,0) -undecene-7 was used as a curing accelerator, and impregnated with 45% by weight of a resin. I got a glass cloth. Similarly, stack seven glass cloths and copper foil on top of them, 170 ℃, 70kg / cm
^The laminate was obtained by heat and pressure molding for ² , 60 minutes. The bending strength and the peel strength of the copper foil before and after boiling of the obtained laminated plate were measured according to JIS-C-6481. The results are shown in Table 6.

[0056]

INDUSTRIAL APPLICABILITY The epoxy resin composition of the present invention has the excellent effects of providing a cured product having excellent storage stability and moldability, low hygroscopicity, and high adhesiveness, and can be used for laminated board materials and electronic parts. When used as a sealing material, the reliability of the product can be improved.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Toshiaki Ishii 7-1 Omika-cho, Hitachi City, Ibaraki Hitachi Ltd. Hitachi Research Laboratory (72) Inventor Akira Nagai 1-chome, Omika-cho, Hitachi City, Ibaraki Prefecture No. 1 Hitachi Ltd., Hitachi Research Laboratory (72) Inventor Masahiko Ogino 7-1-1 Omika-cho, Hitachi City, Hitachi City, Ibaraki Prefecture 72 Hitachi Ltd. Hitachi Research Laboratory (72) Inventor, Ryo Mogi Omi Mika, Hitachi City, Ibaraki Prefecture 7-1-1, Machi, Hitachi, Ltd. Hitachi Research Laboratory (72) Inventor Hiroki Yukishima 1500 Ogawa, Shimodate, Ibaraki Prefecture Hitachi Chemical Co., Ltd. Shimodate factory

Claims (7)

[Claims] 1. An epoxy resin composition comprising an epoxy resin, a curing agent, a curing accelerator, a filler or a fibrous reinforcing material as an essential component, wherein the curing accelerator is represented by the general formula (1): (In the formula, X is a quaternary phosphonium ion, and R is C1 to C
4, an alkyl group and an alkoxy group, and n represents an integer of 1 to 2. ) An epoxy resin composition, which is an organic phosphorus compound represented by 2. The epoxy resin composition according to claim 1, wherein the epoxy resin has the general formula (2): (In the formula, R represents a hydrogen atom or a methyl group and may be different from each other. N is an integer of 0 to 2.) An epoxy resin having a biphenyl skeleton or an epoxy having a dicyclopentadiene skeleton. An epoxy resin composition comprising a resin or at least one kind of an epoxy resin having a naphthalene skeleton. 3. The epoxy resin composition according to claim 1, wherein the curing agent is represented by the general formula (3): (In the formula, m represents an integer of 1 to 10.) A polycondensation product of phenol and aralkyl ether, or a phenolic compound having a dicyclopentadiene skeleton or a naphthalene skeleton is contained in an amount of 100 to 30% by weight of the entire curing agent. % Of the epoxy resin composition. 4. The epoxy resin composition according to claim 1, wherein the curing accelerator represented by the general formula (1) is blended in an amount of 1 to 50 mmol with respect to 100 parts by weight of the epoxy resin. A characteristic epoxy resin composition. 5. The epoxy resin composition according to claim 3, wherein the curing agent represented by the general formula (3) is blended in an amount of 0.5 to 1.5 equivalents with respect to the epoxy resin. An epoxy resin composition characterized by: 6. The epoxy resin composition according to claim 1, wherein the filler is spherical or prismatic with a particle size distribution of 0.1 to 100 μm or a combination of both, and contains 50 to 90% by volume with respect to the entire composition. An epoxy resin composition characterized by the above. 7. The epoxy resin composition according to claim 1, wherein the fibrous reinforcing material is based on inorganic or organic fibers and is contained in an amount of 10 to 80% by weight based on the total weight of the composition. Resin composition.