JPH06322073A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To obtain an epoxy resin composition reduced in the formation of halogen gases at high temperatures, improved in storage stability and moldability and having low hygroscopicity by mixing a specified biphenyl-derived epoxy resin with a curing agent and a cure accelerator. CONSTITUTION:This resin composition is prepared by mixing a biphenyl-derived epoxy resin (A) of formula I (wherein R is H or methyl; and (n) is 0-2) with 0.5-1.5 equivalents, per equivalent of component A, of a curing agent (B) of formula II (wherein (m) is 1-10), 1-15mmol, per 100 pts.wt. component A, of a cure accelerator (C) of formula III (wherein R<1> to R<6> are each phenyl, butyl or a cyclohexane ring), and optionally 50-90vol.% inorganic filler (D) of a mean particle diameter of 0.1-30mum.

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 encapsulating laminated plates, electronic parts, etc., and in particular, it has excellent storage stability and moldability, and the cured product obtained is free at high temperatures. The present invention relates to an epoxy resin composition having a low amount of halogen generation and a low hygroscopicity.

[0002]

2. Description of the Related Art Epoxy resins are required to have higher performance as their applications are expanded as insulating materials, coating materials, encapsulating materials, laminating materials, and prepreg materials in the fields of electric equipment and electronic parts. It is getting tougher.

In particular, since electronic devices are required to be small and lightweight and have high performance, high density mounting of semiconductor parts used therefor is strongly demanded, and recently, a surface mounting type semiconductor suitable for high density mounting is mainstream. There is. Furthermore, packages are becoming smaller and thinner year after year,
A thin package with a thickness of 1 mm has already been put to practical use, and recently, a package with a thickness of 0.5 mm or less has been developed.

As a measure for improving the mounting density, there have been proposed (1) a surface mounting method of soldering a component on the surface of a substrate, (2) a method of mounting an electronic component on a printed circuit board, and the like. Particularly, in the surface mounting method, the package temperature at the time of mounting reaches 200 ° C. or more, so that when a large amount of water is present in the package, it is rapidly vaporized and its volume expands, and its vapor pressure causes the chip and the sealing material to be separated. May cause the interface of the product 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.

As a resin sealing method for electronic parts such as semiconductors,
For the purpose of cost reduction and mass productivity improvement of the encapsulation material, automation of the molding machine and multi-pot molding that reduces runners, sprues, etc. that are unnecessary after molding have been performed as much as possible. The tablet-type multi-pot method requires a sealing resin with an excellent pot life. However, a sealing resin that satisfies various reliability, particularly moisture resistance and pot life at the same time, has not yet been developed, and high performance of the sealing resin material is strongly desired.

In contrast to the above, studies have been made on increasing the glass transition temperature of the encapsulating resin, reducing the moisture absorption rate, improving the adhesive strength, or a latent curing accelerator. Particularly in a thin semiconductor package, it is effective to reduce the moisture absorption and increase the adhesion of the sealing resin material. Specifically, an epoxy resin composition comprising an epoxy resin having a biphenyl skeleton as a sealing resin and a curing agent for a phenol aralkyl resin (Japanese Patent Laid-Open No. Hei 3 (1998)
No. 207714, JP-A-4-48759), or a low hygroscopic epoxy resin composition having a naphthalene skeleton (JP-A-4-502223, JP-A-4-199).
No. 856, Japanese Patent Application Laid-Open No. 4-199857) and the like are disclosed.

[0008]

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

[0009] Further, if a sealed product of an electronic component such as a semiconductor is left at high temperature, Au wire / Al electrode or Au electrode /
There is a problem that the joint portion of the Al wire is easily corroded by the free halogen.

The present invention has been made in view of the above circumstances, and its object is to provide a storage halogen and a moldability which are excellent, a high adhesive strength and a low hygroscopicity, and a free halogen which is heated at a high temperature. An object of the present invention is to provide an epoxy resin composition in which the generation amount of

[0011]

Means for Solving the Problems In order to solve the above-mentioned problems, the inventors of the present invention have the effects of glass fibers, glass cloth, fillers, coupling agents, release agents, etc. The mixing conditions of each material and the molding conditions were thoroughly studied. As a result, they have found that the above problems can be dramatically improved by using a specific epoxy resin, a curing agent, and a curing accelerator, and completed the present invention. The gist of the present invention is as follows.

(A) General formula [1]

[0013]

[Chemical 7]

(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), and (b) a general formula [2. ]

[0015]

[Chemical 8]

(Wherein m represents an integer of 1 to 10), (c) general formula [3]

[0017]

[Chemical 9]

(In the formula, R ^{1 to} R ⁶ represent a phenyl group, a butyl group and a cyclohexane ring and may be different from each other.) A curing accelerator represented by the formula: .

The epoxy resin represented by the above general formula [1] is a biphenyl type epoxy resin having two or more epoxy groups per molecule and a biphenyl skeleton.

It should be noted that bisphenol A-type, F-type or S-type epoxy resins, novolac-type epoxy resins, o-cresol novolac-type epoxy resins, which are other commonly used epoxy resins, are used within a range that does not impair the object of the present invention. An epoxy resin, a polyfunctional epoxy resin having a naphthalene skeleton, an epoxy resin of tri- or tetra (hydroxyphenyl) alkane, an alicyclic epoxy resin and the like can be used in combination.

The curing agent represented by the above general formula [2] is a polycondensation product of a phenol having at least two hydroxyl groups per molecule and an aralkyl ether, which is 0.5 to 1. 5 equivalents, preferably 0.8-1.2
Add the equivalent amount. If the amount is less than 0.5 equivalents, the curing of the epoxy resin will be insufficient and the cured product will have poor heat resistance, moisture resistance and electrical properties. On the other hand, if the amount 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 characteristics and moisture resistance. In addition, a condensate with another phenol such as a phenol novolac resin can be used together within a range not impairing the object of the present invention.

The curing accelerator represented by the general formula [3] is an organic boron salt of an organic phosphine compound. Specific examples include triphenylphosphine / triphenylboron, tributylphosphine / triphenylboron, tricyclohexylphosphine / triphenylboron and the like.

The above-mentioned curing accelerator can be used in the same manner as a usual curing accelerator. However, in order to reduce voids generated during molding, the curing accelerator is previously heated (120 ° C. or more) and dissolved in the curing agent. It is desirable to use. The curing accelerator is 1 to 15 m with respect to 100 parts by weight of the epoxy resin.
It is desirable to mix in the range of mol, preferably 5 to 10 mmol.

When the epoxy resin composition of the present invention is applied to a semiconductor encapsulating material or a general molding material, the inorganic filler may be contained in an amount of 50 to 90% by volume based on the whole composition, if necessary.
It can be blended. The inorganic filler is added for the purpose of improving the thermal expansion coefficient, thermal conductivity and elastic modulus of the cured product. Therefore, if it is less than 50% by volume, these properties cannot be sufficiently improved, and if it exceeds 90% by volume, the viscosity is remarkably increased and the fluidity is lowered to make molding difficult. As such an inorganic filler, fine powder of fused silica, crystalline silica, alumina, calcium carbonate, zirconium silicate, calcium silicate, talc, clay, mica and the like can be used.

The average particle size of these fillers is 0.1 to 30.
The range of μm is desirable, and when the average particle size is less than 0.1 μm, the viscosity of the resin composition is remarkably increased and molding becomes difficult.
On the other hand, if the average particle size exceeds 30 μm, the resin component and the filler are easily separated during molding, and the cured product becomes non-uniform, resulting in variations in physical properties and deterioration of the filling property into narrow gaps. Especially when the filler is blended in an amount of 75% by volume or more,
The shape of the filler is preferably such that the proportion of spherical products is larger than that of prisms, and the one having a particle size distribution in a wide range of 0.1 to 100 μm is desirable. Since such a filler tends to have a close-packed structure, the viscosity of the material is relatively unlikely to increase even if the blending amount is increased, so that a composition having excellent fluidity can be obtained.

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, when an epoxy resin composition containing the above-mentioned filler is used, a laminated board having a smaller thermal expansion coefficient than an ordinary laminated board can be obtained.

In the present invention, a flexibilizing agent or the like can be used as required to strengthen the resin cured product and reduce the elastic modulus. Although the flexibilizer is incompatible with the epoxy resin composition, the elastic modulus of the cured product can be lowered without lowering the glass transition temperature. As such a flexibilizing agent, a butadiene-acrylonitrile-based copolymer or an amino group at the terminal or side chain thereof,
Modified copolymers having epoxy groups and carboxyl groups, butadiene-based flexibilizers such as acrylonitrile-butadiene-styrene copolymers, silicone-based elastomers having amino groups, hydroxyl groups, epoxy groups or carboxyl groups at the terminals or side chains. The silicone-based flexibilizing agent is particularly useful in terms of moisture resistance and purity. The blending amount of the flexibilizer is preferably in the range of 2 to 20% by weight based on the total resin composition. When the blending amount of the flexibilizing agent is less than 2% by weight, there is almost no effect on the toughness and low elastic modulus of the cured product.
On the other hand, if it exceeds 20% by weight, the fluidity of the resin composition and the mechanical strength at high temperature are extremely lowered, and the flexibilizer floats on the surface of the cured resin, so that the molding die is significantly soiled. Become.

In addition to the above, the resin composition of the present invention may optionally contain, as a coupling agent for increasing 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. As the colorant, known compounds such as carbon black, titanium oxide, red lead and red iron oxide can be used.

[0029]

The epoxy resin composition of the present invention exhibits excellent storage stability because the organic boron salt of the organic phosphine compound used as the curing accelerator does not accelerate the curing reaction at around room temperature and is 150 ° C. or higher. This is because it has the property of promptly promoting the curing reaction.

Another reason is that the activity of accelerating the curing reaction does not change so much even if 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 and the curing agent component are relatively low in temperature. It is considered that this is because it has an effect of selectively reacting and reducing volatile components generated when the resin is cured. In particular, it is considered that the void can be further reduced if the curing accelerator and the curing agent are preliminarily heated and dissolved at a temperature of 120 ° C. or higher because the above effect is more prominent.

The cured product of the epoxy resin composition of the present invention is
The generation of free halogen compounds is small when left at a high temperature of 00 ° C or higher because the oxide formed on the surface of the cured product when the cured product is left at a high temperature is relatively stable and oxidative deterioration This is because it is difficult to proceed inside. Further, in the case of a molded product containing a filler, it is considered that a dense molded product with few defects such as voids and cavities can be obtained.

Next, the reason why the epoxy resin composition of the present invention exhibits a lower hygroscopicity than the conventional resin system is that the biphenyl type epoxy resin is chemically structurally hydrophobic as compared with the conventional resin. Further, it is considered that since the cured product has a high density, the packing of the molecular chains is dense, and the formed network structure is less likely to allow water to permeate.

The high adhesive strength is due to the low glass transition temperature of the cured product and the high flexibility of the resin.
It is considered that the residual stress generated in the cured resin is small. In particular, in the epoxy resin composition of the present invention, such characteristics are exhibited because the curing accelerator used in the present invention has a large effect of densely packing the molecules and increasing the flexibility of the resin. it is conceivable that. Further, 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 5 and Comparative Examples 1 and 2] The epoxy resin compositions shown in Table 1 were melt-kneaded with a biaxial roll heated to about 60 to 100 ° C for about 10 minutes, then cooled and pulverized. The target sealing material was obtained. In addition, in Examples 4 to 5, the curing accelerator was previously mixed with the phenol aralkyl resin at 140 ° C. for 15 minutes.
This is an example of using after heating and melting for a minute.

The sealing material thus obtained was heated at 180 ° C. for 7 hours.
Transfer molding was performed under conditions of 0 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 and evaluated. The measurement results are shown in Table 2.

[0039]

[Table 1]

In the table, the melt viscosity is the maximum flow rate when 2 g of the sealing material is extruded with a load of 0.98 MPa from a die nozzle (inner diameter 1 mmφ × length 10 mm) of a high-level flow tester heated to 180 ° C. Calculated from

For spiral flow, a mold for spiral flow measurement specified in EMMI-1-66 is sandwiched between upper and lower hot plates of a transfer molding machine, and 20 g of a sealing material is molded under the above conditions. The length was evaluated.

The hot hardness was measured by using a Barcol hardness tester, which was obtained by transfer molding a disc having a diameter of 20 mmφ, and immediately after the molding die was opened.

The internal void of the molded product has the above diameter of 20 mmφ.
The disc was observed with a soft X-ray fluoroscope and evaluated.

Saturated moisture absorption rate is 90 mm diameter x 2 mm thickness
The disc was placed in a double pressure vessel of tetrafluoroethylene-SUS and was allowed to absorb moisture in an atmosphere of 60 ° C./100% RH for 240 hours.

Table 3 shows each sealing material at 40 ° C./humidity of 20%.
The changes over time in the fluidity (spiral flow) and the curability (hardness at the time of heating) when stored for 7 days under RH and 40 ° C./humidity 60% RH were shown.

[0046]

[Table 2]

[0047]

[Table 3]

From Table 2, it can be seen that the encapsulating material of this example has few voids and excellent moldability, and the molded product has low hygroscopicity and high adhesiveness.

Further, from Table 3, the sealing material of the comparative example is 40
When stored at ℃ / 20% RH and 60% RH, the fluidity decreases, and when stored at 40 ° C / 60% RH, the curability also decreases. 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 sealing material was applied at 180 ° C. and 70 kg / c.
m ² for 90 seconds, transfer molding and diameter 90
A disk of mmφ × thickness 2 mm was obtained. The disc was heat-treated in a thermostat at 180 ° C. for a predetermined time, and then mill mill TI-100.
It was pulverized with a mold (manufactured by HEIKO), and 5 g of the fine powder was placed in a polytetrafluoroethylene-SUS double pressure vessel together with 50 ml of pure water 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). The results are shown in Table 4.

[0051]

[Table 4]

Example 6 100 parts by weight of a biphenyl type epoxy resin (epoxy equivalent 188) as an epoxy resin, 15 parts by weight of a brominated epoxy resin (epoxy equivalent 375), and 100 parts of a phenol aralkyl resin (OH equivalent 170) as a curing agent. Parts by weight, 5 parts by weight of triphenylphosphine / triphenylboron as a curing accelerator, 10 parts by weight of polydimethylsiloxane having a terminal amino group as a flexible agent and having a molecular weight of about 30,000, and 10 parts by weight of epoxysilane as a coupling agent. Parts were dissolved in methyl ethyl ketone and prepared so that the melt viscosity at 23 ° C. was 20 to 100 poises.

A plain weave E glass cloth having a thickness of 50 μm was immersed in this to obtain a 45% by weight resin-impregnated glass cloth.
Seven pieces of this glass cloth and a copper foil were superposed on the glass cloth and heated and pressed at 170 ° C. and 70 kg / cm ² for 60 minutes to form a laminated plate. The obtained laminated plate is JIS-C-64
Bending strength (20 ° C. and 120 ° C.), moisture absorption rate after 8 hours of boiling, and peel strength of the copper foil were measured according to 81. The results are shown in Table 5.

Comparative Example 3 As an epoxy resin, an o-cresol novolac type epoxy resin (epoxy equivalent 19
5) In the same manner as in Example 6 except that 100 parts by weight of 1,8-diazabicyclo- (5,4,0) -undensene-7 was used as a curing accelerator, a 45% by weight resin-impregnated glass cloth was obtained. It was Seven pieces of this glass cloth were overlaid with a copper foil and heated and pressed at 170 ° C. and 70 kg / cm ² for 60 minutes to form a laminated plate. The physical properties of the obtained laminated plate were measured in the same manner as in Example 6. The results are shown in Table 5.

[0055]

[Table 5]

[0056]

INDUSTRIAL APPLICABILITY The epoxy resin composition of the present invention has excellent storage stability and moldability as compared with conventional ones, and has an excellent effect of giving a cured product having low water absorption and high adhesiveness. When used as a plate material or a sealing material for electronic components, the reliability of the product can be improved.

Front Page Continuation (72) Inventor Satoshi Eguchi 7-1 Omika-cho, Hitachi City, Ibaraki Hitachi Ltd. Hitachi Research Laboratory (72) Inventor Kazuhiro Suzuki 1-chome, Omika-cho, Hitachi City, Ibaraki Prefecture Hitachi, Ltd. Hitachi Research Laboratory (72) Inventor Toshiaki Ishii 7-chome, No. 1 Omika-cho, Hitachi City, Ibaraki Prefecture Hitachi Ltd. Hitachi Research Laboratory (72) Inventor Hiroyuki Yukijima Yuki City, Ibaraki Prefecture 1772-1 Hitachi Chemical Co., Ltd. Minami-Yuki Plant (72) Inventor Hiroshi Suzuki 1721 Kagoku, Yuki City, Ibaraki Prefecture Hitachi Chemical Co., Ltd. Minami-Yuki Plant

Claims (5)

[Claims] 1. (a) General formula [1]: (In the formula, R represents a hydrogen atom or a methyl group and may be different from each other, n represents an integer of 0 to 2.), (b) a general formula [2] 2] (In the formula, m represents an integer of 1 to 10.), (c) General formula [3] (In the formula, R ^{1 to} R ⁶ represent a phenyl group, a butyl group, and a cyclohexane ring and may be different from each other.) A curing accelerator represented by the formula: 2. (a) General formula [1]: (In the formula, R represents a hydrogen atom or a methyl group and may be different from each other, n represents an integer of 0 to 2.), (b) a general formula [2] 5] (In the formula, m represents an integer of 1 to 10.), (c) General formula [3] (In the formula, R ^{1 to} R ⁶ represent a phenyl group, a butyl group and a cyclohexane ring and may be different from each other.), (D) an inorganic filler having an average particle size of 0.1 to 30 μm Agent is 50 ~
90% by volume of the epoxy resin composition. 3. The curing agent represented by the general formula [2] is
With respect to the epoxy resin represented by the general formula [1],
The epoxy resin composition according to claim 1 or 2, which is blended in an amount of 5 to 1.5 equivalents. 4. The epoxy resin composition according to claim 1, wherein the curing accelerator represented by the general formula [3] is dissolved in the curing agent (b) and blended in advance. 5. The curing accelerator represented by the general formula [3] is blended in an amount of 1 to 15 mmol with respect to 100 parts by weight of the epoxy resin represented by the general formula [1].
The epoxy resin composition according to any one of to 4.