JP2002060468A - Epoxy resin composition, prepreg, and copper-clad laminate using the prepreg - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an epoxy resin composition which, though it does not contain a halogenous flame retardant, can give an IC package substrate board having high heat resistance, low thermal expansion, and excellent flame retardance. SOLUTION: The resin composition contains (A) an epoxy resin having at least three epoxy groups, (B) a phenol resin-based curing agent having at least three phenolic hydroxyl groups, (C) 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10- oxide, (D) a triarylphosphine oxide, and (E) spherical fused silica having max. particle size of 24 μm or lower, an average particle size of 2 μm or higher but not higher than 5 μm, and a specific surface area of 5 m2/g or lower as essential ingredients.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an epoxy resin composition, prepreg, which has excellent flame retardancy without using a halogen-based flame retardant, and exhibits excellent heat resistance and dimensional stability. It relates to the used copper-clad laminate.

[0002]

2. Description of the Related Art In the field of semiconductors, the trend of shifting from conventional surface mounting to area mounting has progressed due to the progress of high-density mounting technology, and new packages such as BGA and CSP have appeared and are increasing. For this reason, rigid substrates for interposers have attracted more attention than ever before, and demands for substrates having high heat resistance and low thermal expansion have increased. On the other hand, resin members used for these semiconductors are often required to have flame retardancy. Conventionally, in order to impart this flame retardancy, it has been common to use a halogen-based flame retardant such as a brominated epoxy in an epoxy resin. However, since dioxin may be generated from the halogen-containing compound,
With the recent increase in environmental problems, the use of halogen-based flame retardants has been avoided, and a wide range of industries has been demanded for halogen-free flame retardant systems. Phosphorus-based flame retardants have been spotlighted in response to the demands of such times, and phosphate esters and red phosphorus have been studied.However, these conventional phosphorus-based flame retardants are easily hydrolyzed and have a poor reaction with the resin. There are problems that the solderability is lowered and the glass transition temperature is lowered.

[0003]

DISCLOSURE OF THE INVENTION The present invention has been made to solve such a problem, and is an epoxy which is halogen-free, has excellent flame retardancy, and can exhibit high heat resistance and low thermal expansion characteristics. A resin composition, a prepreg, and a copper-clad laminate are provided.

[0004]

SUMMARY OF THE INVENTION The present invention provides a polyfunctional epoxy resin which contributes to heat resistance, a phenolic resin-based curing agent, a phosphorus compound having a specific structure having flame retardancy and excellent hydrolysis resistance, and low thermal expansion. The technical gist is an epoxy resin composition suitable for a copper-clad laminate containing a specific spherical silica exhibiting water resistance and low water absorption as an essential component, and the above-described object has been achieved by such a composition. .

Specifically, an epoxy resin having three or more epoxy groups in one molecule, a phenol resin-based curing agent having three or more phenolic hydroxyl groups in one molecule,
10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, triarylphosphine oxide, and a maximum particle size of 24 μ or less and an average particle size of 2 μ
An epoxy resin composition characterized in that spherical fused silica having a specific surface area of 5 m ² / g or less and a specific surface area of 5 m ² / g or less is used as an essential component, and further, in addition to these components, a coupling agent is used as an essential component. Characterized epoxy resin compositions, and impregnating the substrate with these epoxy resin compositions,
It is a prepreg obtained by drying and a copper-clad laminate formed by heating and using the prepreg.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The epoxy resin (A) having three or more epoxy groups in one molecule used in the present invention includes orthocresol novolak epoxy resin, phenol novolak epoxy resin, bisphenol A novolak epoxy resin and the like. Derivatives such as novolak type epoxy resin, trishydroxyphenylmethane type epoxy resin and corresponding epoxy resin having an alkylated aromatic ring, glycidyl etherified product of 1,1,2,2-tetrakishydroxyphenylethane, and dimer thereof ,
Examples thereof include a tetrakishydroxyphenylethane type epoxy resin such as a trimer, and the epoxy resin is a phosphorus compound described below, which is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide. Since the epoxy group in the resin decreases due to the reaction of the triarylphosphine oxide with the epoxy group, an epoxy resin having three or more functions is essential to keep the glass transition temperature high. In particular, among trifunctional or higher functional epoxy resins, novolak type epoxy resin (A1) and at least one epoxy resin selected from the group consisting of trishydroxyphenylmethane type epoxy resin and tetrakishydroxyphenylethane type epoxy resin (A
When 2) is combined, at least one epoxy resin (A2) selected from the group consisting of a trishydroxyphenylmethane type epoxy resin and a tetrakishydroxyphenylethane type epoxy resin can increase the crosslink density and increase the glass transition temperature, On the other hand, the novolak-type epoxy resin (A1) can prevent the disadvantages of the epoxy resin (A2) described above, such as brittleness due to excessively high water absorption and cross-linking density, and decrease in adhesion. In particular, among the novolak-type epoxy resins (A1), ortho-cresol novolak epoxy resin is preferable because the water absorption can be reduced. In the present invention, the proportion of the component (A) in the epoxy resin composition is preferably from 10 to 50% by weight. If the content is less than 10% by weight, the binder component may be reduced, and the heat resistance may be reduced, or the resin component may be reduced, so that the moldability may be deteriorated. If it exceeds 50% by weight, the proportion of the filler decreases, and the thermal expansion and the water absorption increase, which is not preferable.
In addition, as the epoxy resin, an epoxy resin other than the component (A), for example, a bisphenol A type epoxy resin may be blended in an amount of 30% by weight or less of the entire epoxy resin.

The phenolic resin-based curing agent having three or more phenolic hydroxyl groups in one molecule of component (B) is exemplified by phenol novolak, bisphenol A novolak, phenol aralkyl resin and the like. Phenol novolak having a relatively small equivalent weight and capable of easily removing low-functional monomers is preferable.
In the present invention, the component (B) has a molar ratio of the epoxy group of the epoxy resin to the total (equivalent ratio) of the phenolic hydroxyl group and other active hydrogen of the component (B) of 0.8 to 1.2.
It is preferable to add so as to be as follows. Outside this range, the glass transition temperature and the electrical properties may be reduced.

Component (C) 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, which is one of the flame retardant components of the present invention, is characterized in that the hydrogen bonded to phosphorus is an epoxy group. It is a reactive phosphorus compound that reacts with, and is a very excellent phosphorus-based flame retardant without hydrolyzing to increase water absorption or reducing adhesion like conventional phosphate esters and red phosphorus . However, on the other hand, since this compound has an effect of delaying the curability of the resin, there is a case where a problem occurs in the curability when the press molding time is shortened. (D) Triarylphosphine oxide, which is the other component of the flame retardant component, is considered not to react with the matrix resin or to have low reactivity. However, it is excellent in hydrolysis resistance, and in addition, like HCA, Does not affect curability. Therefore, when the components (C) and (D) are used in combination, good solder heat resistance can be realized without deteriorating water absorption and adhesion while maintaining flame retardancy and curability. This (C)
The weight ratio of (D) to (D) is preferably from 1: 4 to 4: 1.
Outside of this range, the combined effect may be diminished. The total added amount of (C) and (D) of the present invention is preferably 0.5 to 10% by weight based on the entire epoxy resin composition.
If it is less than 0.5% by weight, the flame-retardant effect may be reduced. If it exceeds 10% by weight, the glass transition temperature may be lowered. Examples of the triarylphosphine oxide include triphenylphosphine oxide, trishydroxyphenylphosphine oxide, bis (hydroxyphenyl) phenylphosphine oxide, trisaminophenylphosphine oxide, and bis (aminophenyl) phenylphosphine oxide. The aryl group of the oxide may be unsubstituted or may have any substituent.

The component (E) of the present invention has a maximum particle size of 24 μm.
Spherical fused silica having an average particle size of 2 μm or more and 5 μm or less and a specific surface area of 5 m ² / g or less. In order to achieve both low thermal expansion and resin fluidity by adding a large amount of filler, spherical fused silica is optimal because it is superior to other fillers.
Among the spherical fused silicas, the maximum particle size is 24 μm or less, and the average particle size is 2 μm or more and 5 μm by laser diffraction particle size distribution measurement.
m and a fused silica having a specific surface area of 5 m ² / g or less according to the BET method are preferred. When coarse particles having a maximum particle size of more than 24 μm are contained, a space caused by the coarse particles is formed between the copper foil and the base material, and when moisture is absorbed, water stays and the solder heat resistance deteriorates. Or the appearance of the glass deteriorates. When the average particle size is smaller than 2 μm or when the specific surface area is 5 m ² / g
In the case where the average particle diameter is larger than the above, the same problem as the case where the coarse particles are contained may occur due to the secondary aggregation of the particles. When the spherical fused silica accounts for 50% by weight or more of the epoxy resin composition, thermal expansion and water absorption are reduced, which is preferable. However,
If the content exceeds 90% by weight, the proportion of the inorganic filler in the epoxy resin composition is too large, and operations such as impregnation become difficult. If necessary, other fillers may be used as long as the properties are not hindered. In this case, a conventionally known filler such as a spherical silica other than a spherical fused silica having a maximum particle size of 24 μm or less, an average particle size of 2 μm or more and 5 μm or less, and a specific surface area of 5 m ² / g or less is used for solder heat resistance and the like. It can be used arbitrarily as long as the characteristics are not deteriorated.

It is preferable to further use a coupling agent in the resin composition of the present invention since the wettability at the interface between the resin and the filler is improved. In particular, silicone oil type coupling agents having two or more repeating units of siloxane bonds and having an alkoxy group are preferably used because they are coated on the filler surface without volatilization even when exposed to high temperatures during prepreg production. Can be In this case, the combined use with the general-purpose silane coupling agent is effective in balancing the wettability with the filler and the fixability of the coupling agent on the surface of the filler.
In the present invention, the content of the component (F) is preferably 0.1 to 5% by weight based on the entire epoxy resin composition. If the amount is less than 0.1% by weight, the coupling agent may not be dispersed on the entire surface of the filler. If it exceeds 5% by weight, the glass transition temperature may decrease.

The epoxy resin composition of the present invention may optionally contain additives other than the above components as long as the properties are not impaired. The epoxy resin composition of the present invention can be applied to a substrate as a varnish using a solvent or without a solvent to obtain a prepreg. As the substrate, a glass woven fabric, a glass nonwoven fabric, or another organic substrate can be used. The epoxy resin composition of the present invention is impregnated into a fiber base material and dried to obtain a prepreg, and one or more of the prepregs is heat-formed together with a copper foil to obtain a copper-clad laminate. These prepregs and copper-clad laminates are also included in the present invention.

[0012]

EXAMPLES Example 1 Orthocresol novolak epoxy resin (Epiclon N-665, manufactured by Dainippon Ink and Chemicals), 25 parts by weight (hereinafter abbreviated as "part"), phenol novolak (softening point: 105 ° C)
9.5 parts, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (manufactured by Sanko Chemical)
After dissolving 0.05 parts of 2-phenyl-4-methylimidazole in a mixed solvent of methyl ethyl ketone and methyl cellosolve for 2 parts, triphenylphosphine oxide 3 parts, and a total of 100 parts of epoxy resin and curing agent, 0.4 parts of an epoxysilane coupling agent (A-187 manufactured by Nippon Unicar) and a silicone oil-type coupling agent A (MAC2101 manufactured by Nippon Unicar) were added to the solution.
1 part was added and stirred, and then 60 parts of spherical fused silica A (spherical fused silica having an average particle size of 4 µ cut from 24 µ or more, specific surface area 2 m ² / g) was added little by little while stirring with an irrigating stirring blade. . When all the components were mixed, the mixture was stirred for 10 minutes using a high-speed stirrer. A glass cloth (thickness: 180 μm, manufactured by Nitto Boseki) is impregnated with the prepared varnish, dried in a heating furnace at 150 ° C. for 6 minutes, and a varnish solid content (a component in the prepreg except glass cloth) is about 50% by weight.
Prepreg was obtained. This prepreg is stacked a predetermined number of times,
Laminate 12μm copper foil on both sides, pressure 40kgf / cm
^2. Heat and pressure molding was performed at 190 ° C. for 60 minutes to obtain a double-sided copper-clad laminate.

The evaluation method of the obtained double-sided copper-clad laminate is as follows.
The BGA evaluation method is shown in FIG. Glass transition temperature Double-sided copper-clad laminate with a thickness of 0.6 mm is entirely etched,
A test piece of 10 mm × 60 mm was cut out from the obtained laminate, and the temperature was raised at 3 ° C./min using a dynamic viscoelasticity measuring apparatus, and the peak position of tan δ was taken as the glass transition temperature. Coefficient of linear expansion The whole surface of the double-sided copper-clad laminate with a thickness of 1.2 mm is etched,
A test piece of 2 mm × 2 mm was cut out from the obtained laminate, and the linear expansion coefficient in the Z direction was measured at 5 ° C./min using TMA. Flame retardant Double-sided copper-clad laminate with a thickness of 0.6mm is etched over the entire surface,
It measured from the obtained laminated board by UL-94 standard and a vertical method. Solder heat resistance A double-sided copper-clad laminate with a thickness of 0.4 mm was manufactured and JISC6
After preparing four test pieces by a method according to 481 and performing a moisture absorption treatment for 4 hours with a pressure cooker,
Was immersed in the solder bath for 120 seconds, and the number of appearance abnormalities was examined.

Package warpage A double-sided copper-clad laminate having a thickness of 0.4 mm produced in the embodiment
Circuit processed for GA. This circuit board (rigid interposer) and the sealing material are EME-7 manufactured by Sumitomo Bakelite.
Using 720, mold temperature 180 ° C, injection pressure 75kg
/ Cm ² , 225 pBGA with a curing time of 2 minutes (package size: 24 × 24 mm, thickness: 1.17 mm, silicon chip size: 9 × 9 mm, thickness: 0.35 mm, chip and bonding pad of circuit board having diameter of 25 μm) (Bonded with a gold wire.) And post-cured at 175 ° C. for 8 hours. After cooling to room temperature, the displacement of the height of the package upper surface was measured diagonally from the gate portion of the package by a surface roughness meter, and the maximum displacement value based on the gate portion was defined as the amount of warpage. The unit is μm. Eight packages obtained by the same method as in the BGA solder crack resistance were left in an environment of 85 ° C. and a relative humidity of 60% for 240 hours.
IR reflow treatment was performed according to the method of C. After the treatment, the presence of peeling and cracks in the inside was observed with an ultrasonic flaw detector, and the number of defective packages was counted. When the number of defective packages is n, it is displayed as n / 8.

Examples 2 to 14 and Comparative Examples 1 to 4 Double-sided copper-clad laminates were obtained in the same manner as in Example 1 with the compositions shown in Tables 1 and 2. The evaluation method is also as described above.
The evaluation results are shown in the lower columns of Tables 1 and 2. The copper-clad laminate obtained using the epoxy resin composition of the present invention has excellent flame retardancy despite not using a halogen compound, and is excellent in evaluation of a laminate alone and an IC package. In addition, it shows excellent soldering heat resistance and, in addition, the warpage after molding is extremely small.

[0016]

[Table 1]

[0017]

[Table 2]

Notes to Table 1) Spherical fused silica A: Spherical fused silica having an average particle size of 4 μ cut from 24 μ or more, specific surface area 2 m ² / g 2) Spherical fused silica B: Spherical fused silica having an average particle size cut from 24 μ or more Spherical fused silica, specific surface area 4 m ² / g 3) Spherical fused silica C: Spherical fused silica having an average particle size of 2.5 μ cut from 24 μ or more, specific surface area 4.5 m ² / g 4) Spherical fused silica D: 24 μ or more Is not cut, spherical fused silica having an average particle size of 22 μm, specific surface area of 2.7 m ²
/ G 5) Spherical fused silica E: Spherical fused silica having an average particle size of 0.6 μm, specific surface area 6 m ² / g 6) Crushed fused silica F: Crushed fused silica having an average particle size of 18 μm, specific surface area 2.2 m ² / G 7) Talc having an average particle size of 5μ 8) Aluminum hydroxide having an average particle size of 12μ 9) Epoxysilane coupling agent: A manufactured by Nippon Unicar
187 10) Silicone oil type coupling agent A: MAC2101 manufactured by Nippon Unicar 11) Silicone oil type coupling agent B: MAC2301 manufactured by Nippon Unicar 12) Orthocresol novolak Epoxy resin: Epicron N-665 manufactured by Dainippon Ink and Chemicals 13) Phenol novolak Epoxy resin: Epicron N-775 manufactured by Dainippon Ink and Chemicals, Inc. 14) Tetrakishydroxyphenylethane type epoxy resin: Epicoat E1031S manufactured by Yuka Shell Epoxy 15) Trishydroxyphenylmethane type epoxy resin: Epicoat E1032 manufactured by Yuka Shell Epoxy 16) Bisphenol A Novolak epoxy resin: softening point 70 ° C, epoxy equivalent 201 17) bisphenol A type epoxy resin: epoxy equivalent 250 18) phenol novolak: Of point 105 ° C., a hydroxyl equivalent of 104 19) bisphenol A novolac: softening point 115 ° C.,
Hydroxyl equivalent 129 20) phenol aralkyl resin: XL-2 manufactured by Mitsui Chemicals, Inc.
25 21) 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (manufactured by Sanko Chemical) 22) 2-Phenyl-4-methylimidazole: The compounding amount is 100 of the total amount of the epoxy resin and the curing agent. 23) Fragmented fused silica G having an average particle size of 3 μm, specific surface area 1
5m ² / g

[0019]

The epoxy resin composition of the present invention has excellent flame retardancy without using a halogen-based flame retardant, and has high heat resistance and low thermal expansion characteristics. Therefore, the copper-clad laminate obtained from the epoxy resin composition of the present invention has excellent solder heat resistance and can provide a substrate for an IC package with a small warpage, which can greatly contribute to related industries.

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Claims (8)

[Claims] (A) an epoxy resin having three or more epoxy groups in one molecule; (B) a phenolic resin-based curing agent having three or more phenolic hydroxyl groups in one molecule;
(C) 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, (D) triarylphosphine oxide, and (E) maximum particle size 24 μm
An epoxy resin composition comprising spherical fused silica having an average particle diameter of 2 μm or more and 5 μm or less and a specific surface area of 5 m ² / g or less as an essential component. 2. The epoxy according to claim 1, wherein the component (A) is at least one epoxy resin selected from the group consisting of a trishydroxyphenylmethane type epoxy resin, a tetrakishydroxyphenylethane type epoxy resin, and a novolak type epoxy resin. Resin composition. 3. The component (A) comprises a novolak epoxy resin (A1) and at least one epoxy resin (A2) selected from the group consisting of a trishydroxyphenylmethane epoxy resin and a tetrakishydroxyphenylethane epoxy resin. The epoxy resin composition according to claim 1, which is essential. 4. The epoxy resin composition according to claim 1, wherein the component (B) is phenol novolak. (A) an epoxy resin having three or more epoxy groups in one molecule, (B) a phenolic resin-based curing agent having three or more phenolic hydroxyl groups in one molecule,
(C) 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, (D) triarylphosphine oxide, (E) maximum particle size of 24 μ or less,
And the average particle size is 2 μm or more and 5 μm or less, and the specific surface area is 5 m
An epoxy resin composition comprising spherical fused silica of ² / g or less and (F) a coupling agent as essential components. 6. The epoxy resin composition according to claim 5, wherein the component (F) is a silicone oil type coupling agent having two or more siloxane bond repeating units and having an alkoxy group. 7. A prepreg obtained by impregnating a fiber base material with the epoxy resin composition according to claim 1 and drying it. 8. A copper-clad laminate obtained by heating and molding the prepreg according to claim 7.