JP2964634B2 - Epoxy composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an epoxy composition having excellent solder heat resistance, moisture resistance reliability and moldability.

<Conventional technology> Epoxy resins are excellent in heat resistance, moisture resistance, electrical properties, adhesiveness, etc., and can be imparted with various properties by formulation, so they are used as industrial materials such as paints, adhesives, and electrical insulating materials. Have been.

For example, as a method of sealing an electronic circuit component such as a semiconductor device, a hermetic seal made of metal or ceramic and a resin seal made of phenol resin, silicone resin, epoxy resin or the like have been conventionally proposed. However, resin sealing with epoxy resin is mainly used in terms of balance between economy, productivity, and physical properties.

On the other hand, recently, the density and automation of component mounting on printed circuit boards have been increasing, and instead of the conventional “insertion mounting method” in which lead pins are inserted into holes in the board, “components are soldered to the board surface” “Surface mounting method” has become popular. Along with this, packages are also shifting from conventional DIP (dual in-line packages) to thin FPPs (flat plastic packages) suitable for high-density mounting and surface mounting.

With the shift to the surface mounting direction, the soldering process, which was not so much a problem in the past, has become a big problem. In the conventional pin insertion mounting method, the lead portion is only partially heated in the soldering process, but in the surface mounting method, the entire package is immersed in a heating medium and heated. As the soldering method in the surface mounting method, a solder bath immersion, heating with a saturated vapor of an inert gas (a vapor phase method), an infrared reflow method, and the like are used. In any case, the entire package is heated to a high temperature of 210 to 270 ° C. It will be heated.
Therefore, the package sealed with the conventional sealing resin has a problem that cracks occur in the resin portion at the time of soldering, the reliability is reduced, and the package cannot be used as a product.

It is said that the occurrence of cracks in the soldering process is due to the fact that the moisture absorbed between the post-curing and the mounting process explosively turns into steam and expands during soldering heating. A method is used in which the package is stored in a completely dried and sealed container and shipped.

Various studies have been made on improvements in the sealing resin. For example,
A method of adding an epoxy resin having a biphenyl skeleton and a rubber component (Japanese Patent Application Laid-Open No. 63-251419), a method of adding an epoxy resin having a biphenyl skeleton and fine powder particles having a particle diameter of 14 μm or less (Japanese Patent Application Laid-Open No. 1-87616) Gazette) has been proposed.

On the other hand, in order to improve the flowability of the sealing resin, a method of adding spherical fused silica fine particles (JP-A-53-102361), JP-A-58-138740, and JP-A-59-84937 are disclosed. ) Or a method of adding an epoxy resin having a naphthalene skeleton (JP-A-2-88621).

<Problem to be Solved by the Invention> However, the method of enclosing the dry package in a container has disadvantages in that the manufacturing process and the handling of the product are complicated, and the product price is high.

In addition, resins improved by various methods have each been effective little by little, but are still not sufficient. A method of adding an epoxy resin having a biphenyl skeleton and a rubber component and an epoxy resin having a biphenyl skeleton and a particle size of 14
The method of adding fine powder particles of μm or less has the effect of improving the soldering heat resistance in a relatively thick package such as QFP (Quat Flat Package).
Thinner packages such as small outline packages have problems such as insufficient solder heat resistance and insufficient fluidity.

Further, when spherical fused silica having an average particle diameter of 5 μm or more, which is generally used for improving fluidity, is added, fluidity is improved, but there is a problem that solder heat resistance is reduced. For the same purpose, the method of adding an epoxy resin having a naphthalene skeleton has a small effect of improving fluidity and is not sufficient.

An object of the present invention is to solve the problem of cracks generated in the soldering step and to provide an epoxy composition having good fluidity during molding, excellent solder heat resistance, and excellent moldability.

<Means for Solving the Problems> The present inventors have achieved the above object by adding crushed silica and spherical silica having a specific particle size to an epoxy resin having a naphthalene skeleton, and have met the object. The inventors have found that an epoxy composition can be obtained, and have reached the present invention.

That is, the present invention relates to an epoxy composition containing an epoxy resin (A), a curing agent (B) and a filler (C), wherein the epoxy resin (A) has the following general formula (I) (However, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ each represent a hydrogen atom, a halogen atom, or a group selected from an alkyl group having 1 to 4 carbon atoms.) The epoxy resin (a) is contained as an essential component, and the filler (C) comprises 99 to 50% by weight of crushed fused silica having an average particle size of 10 μm or less and 1 to 50% by weight of spherical fused silica having an average particle size of 4 μm or less. An epoxy composition, wherein the average particle size of the spherical fused silica is smaller than the average particle size of the crushed fused silica, and the proportion of the filler (C) is 75 to 90% by weight of the whole.

 Hereinafter, the configuration of the present invention will be described in detail.

The epoxy resin (A) in the present invention has the formula (I)
It is important to contain an epoxy resin (a) having a skeleton represented by the following as an essential component.

When the epoxy resin (a) is not contained, the effect of preventing the occurrence of cracks in the soldering step and the effect of heat resistance are not exhibited.

In the above formula (I), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ each represent a hydrogen atom, a halogen atom, or a group selected from an alkyl group having 1 to 4 carbon atoms. R ¹ , R ² , R ³ , R ⁴ , R ⁵ ,
Preferred specific examples of R ⁶ include a hydrogen atom, a methyl group, an ethyl group, a propyl group, an i-propyl group, an n-butyl group,
Examples thereof include a sec-butyl group, a tert-butyl group, a chlorine atom, and a bromine atom.

Preferred specific examples of the epoxy resin (a) in the present invention include 1,5-diglycidylnaphthalene, 1,5-diglycidyl-7-methylnaphthalene, 1,6-diglycidylnaphthalene, and 1,6-diglycidyl-2-. Methylnaphthalene, 1,6-diglycidyl-8-methylnaphthalene, 1,6-
Diglycidyl-4,8-dimethylnaphthalene, 2-bromo-1,6-diglycidylnaphthalene, 8-bromo-1.6-diglycidylnaphthalene and the like can be mentioned.

The epoxy resin (A) in the present invention can contain the above-mentioned epoxy resin (a) in combination with another epoxy resin other than the epoxy resin (a). Other epoxy resins that can be used in combination include, for example, cresol novolak epoxy resin, phenol novolak epoxy resin, biphenyl epoxy resin, various novolak epoxy resins synthesized from bisphenol A and resorcinol, bisphenol A epoxy resin, wire Aliphatic epoxy resin, alicyclic epoxy resin, heterocyclic epoxy resin, halogenated epoxy resin and the like.

The ratio of the epoxy resin (a) contained in the epoxy resin (A) is not particularly limited, and the effect of the present invention is exhibited if the epoxy resin (a) is contained as an essential component, but a more sufficient effect is obtained. In order to exert the effect, usually 30% by weight of the epoxy resin (a) is added to the epoxy resin (A).
As described above, it is necessary that the content be preferably 50% by weight or more.

In the present invention, the compounding amount of the epoxy resin (A) is 3 to
It is 30% by weight, preferably 5 to 25% by weight.

The curing agent (B) in the present invention is an epoxy resin (A)
There is no particular limitation as long as it reacts with and cures. Specific examples thereof include phenol novolak resin, cresol novolak resin, various novolak resins synthesized from bisphenol A and resorcinol, maleic anhydride, phthalic anhydride And acid anhydrides such as pyromellitic anhydride and aromatic amines such as metaphenylenediamine, diaminodiphenylmethane and diaminodiphenylsulfone. For sealing semiconductor devices,
Novolak resins such as phenol novolak and cresol novolak are preferably used from the viewpoint of heat resistance, moisture resistance and storage stability, and two or more curing agents may be used in combination depending on the application.

In the present invention, the amount of the curing agent (B) is usually 1 to 20.
% By weight, preferably 2 to 15% by weight. Further, the mixing ratio of the epoxy resin (A) and the curing agent (B) is such that the chemical equivalent ratio of (B) to (A) is in the range of 0.6 to 1.5, particularly 0.7 to 1.2 from the viewpoint of mechanical properties and moisture resistance. Is preferred.

In the present invention, a curing catalyst may be used to accelerate the curing reaction between the epoxy resin (A) and the curing agent (B). The curing catalyst is not particularly limited as long as it promotes the curing reaction. For example, 2-methylimidazole, 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methyl Imidazole compounds such as imidazole and 2-heptadecyl imidazole, triethylamine, benzyldimethylamine, α-methylbenzyldimethylamine,
Tertiary amine compounds such as-(dimethylaminomethyl) phenol, 2,4,6-tris (dimethylaminomethyl) phenol, 1,8-diazabicyclo (5,4,0) undecene-7, zirconium tetramethoxide, zirconium Tetrapropoxide, tetrakis (acetylacetonato)
Organic metal compounds such as zirconium and tris (acetylacetonato) aluminum; and organic phosphine compounds such as triphenylphosphine, trimethylphosphine, triethylphosphine, tributylphosphine, tri (p-methylphenyl) phosphine, and tri (noniphenyl) phosphine. . Of these, organic phosphine compounds are preferred from the viewpoint of moisture resistance, and triphenylphosphine is particularly preferably used. Two or more of these curing catalysts may be used in combination depending on the application, and the addition amount thereof is preferably in the range of 0.1 to 10 parts by weight based on 100 parts by weight of the epoxy resin (A).

The filler (C) in the present invention is composed of 99 to 50% by weight of crushed fused silica having an average particle size of 10 μm or less and 1 to 50% by weight of spherical fused silica having an average particle size of 4 μm or less. It is smaller than the average particle size of silica. The filler (C) is composed of 97 to 70% by weight of crushed fused silica having an average particle diameter of 10 μm or less and 3 to 30% by weight of spherical fused silica having an average particle diameter of 4 μm or less. Those smaller than the particle size are particularly preferred.
If the average particle size of the crushed fused silica exceeds 10 μm, the solder heat resistance is insufficient, and if it is 10 μm or less, there is no particular limitation, but from the viewpoint of fluidity, 3 μm or more and 10 μm or more.
The following are preferably used. Here, as long as the average particle size of the crushed fused silica is 10 μm or less, two or more types of crushed fused silica having different average particle sizes may be used in combination. If the average particle diameter of the spherical fused silica exceeds 4 μm, the solder heat resistance and the fluidity become insufficient.
Those having a size of at least 4 μm are preferably used. Here, if the spherical fused silica has an average particle size of 4 μm or less,
Two or more kinds of fused silica particles having different average particle diameters may be used in combination. Here, the average particle diameter means a particle diameter (median diameter) at which the cumulative weight becomes 50%. In the filler (C), it is important that the average particle size of the spherical fused silica is smaller than the average particle size of the crushed fused silica. If the average particle size of the spherical fused silica is larger than the average particle size of the crushed fused silica, its fluidity improving effect is significantly reduced. The average particle size of the spherical fused silica may be smaller than the average particle size of the crushed fused silica, preferably, the average particle size of the spherical fused silica is 2/3 or less of the average particle size of the crushed fused silica, and particularly preferably. 1
/ 2 or less. Further, when the ratio of the crushed fused silica to the spherical fused silica is not in the above range, a composition excellent in solder heat resistance and moldability cannot be obtained. In the present invention, the proportion of the filler (C) is from 75 to 90% by weight, more preferably from 77 to 88% by weight. 75% by weight of filler (C)
If it is less than 90%, the solder heat resistance is insufficient, and if it exceeds 90% by weight, the fluidity is insufficient. The fused silica as used herein means amorphous silica having a true specific gravity of 2.3 or less. The production method does not necessarily have to go through a molten state, and any production method can be used. For example, a method of melting crystalline silica, a method of synthesizing from various raw materials, and the like can be mentioned.

In the epoxy composition of the present invention, as a filler, besides fused silica (C), crystalline silica, calcium carbonate, magnesium carbonate, alumina, magnesia, clay, talc, calcium silicate, titanium oxide, antimony oxide, asbestos, glass fiber Etc. can be added.

In the present invention, it is preferable from the viewpoint of reliability that a filler such as fused silica (C) is subjected to a surface treatment in advance with a coupling agent such as a silane coupling agent or a titanate coupling agent.

Examples of the coupling agent include silane coupling agents such as epoxy silane, amino silane, and mercapto silane. Above all, from the viewpoint of productivity, when soldering heat resistance, moisture resistance reliability, and low-pressure transfer molding machines are used, thick burrs are generated, plunger operability is reduced, and workability is reduced. And an aminosilane coupling agent (D) whose amino groups are all secondary. The epoxy composition of the present invention includes a halogen compound such as a halogenated epoxy resin, a flame retardant such as a phosphorus compound, a flame retardant auxiliary such as antimony trioxide, a colorant such as carbon black and iron oxide, a silicone rubber, and a styrene-based block. Copolymers, olefin copolymers, modified nitrile rubber, modified polybutadiene rubber and other elastomers, polyethylene and other thermoplastic resins,
A releasing agent such as a long-chain fatty acid, a metal salt of a long-chain fatty acid, an ester of a long-chain fatty acid, an amide of a long-chain fatty acid, or paraffin wax, and a crosslinking agent such as an organic peroxide can be optionally added. The epoxy composition of the present invention is preferably melt-kneaded, and is produced, for example, by melt-kneading using a known kneading method such as a Banbury mixer, a kneader, a roll, a single-screw or twin-screw extruder and a co-kneader. .

<Example> Hereinafter, the present invention will be specifically described with reference to examples.

Examples 1 to 6 and Comparative Examples 1 to 5 The fused silica shown in Table 2 and the silane coupling agent shown in Table 3 were added to the formulation shown in Table 1 in the composition ratio shown in Table 4 respectively. Was dry blended with a mixer. This was heated and kneaded for 5 minutes using a mixing roll having a roll surface temperature of 90 ° C., and then cooled and pulverized to produce an epoxy composition.

Using this composition, low-pressure transfer molding
The composition was molded at 175 ° C. × 2 minutes, and the physical properties and moldability of each composition were measured by the following physical property and moldability measurement methods. Table 4 shows the results.

Solder heat resistance: Molded 24 28-pin TSOP with simulated element, post-cured at 180 ° C for 5 hours, and 1 at 85 ° C and 85% RH
After humidification for 6 hours, the mixture was heated to 245 ° C. for 10 seconds using an IR reflow furnace, and the ratio of the number of TSOPs without cracks was determined.

PCBT after solder immersion: TSOP after soldering at 125 ° C, 85% R
H, USPCBT was performed at a bias voltage of 10 V, and the time until the cumulative failure rate became 50% was obtained.

Filling property: A 160-pin QFP was formed, and the presence or absence of unfilling was visually determined.

Thick burrs: Thick burrs were measured by low pressure transfer molding using a flash measurement mold at 175 ° C for 90 seconds.

As shown in Table 4, the epoxy compositions of the present invention (Examples 1 to 4) are excellent in moldability such as solder heat resistance, reliability of moisture resistance after solder immersion, and filling property. On the other hand, in Comparative Example 3 in which the ratio of the filler (C) was less than 75% by weight, solder heat resistance was low, and in Comparative Examples 4 and 5 in which the fused silica of the present invention was not used, solder heat resistance and fillability were low. Inferior.

In Comparative Examples 1 and 2 in which the epoxy resin (A) of the present invention was not contained in the epoxy resin (A),
Poor moisture resistance reliability after solder immersion.

Further, in Examples 5 and 6 using a secondary aminosilane compound as the silane coupling agent, not only are the solder heat resistance, the moisture resistance reliability after solder immersion, and the filling property excellent, but also the thickness burrs are reduced.

<Effect of the Invention> Since the epoxy composition of the present invention contains a specific epoxy resin, a curing agent, and a specific fused silica, it has excellent solder heat resistance, moisture resistance reliability after solder immersion, and moldability.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-88621 (JP, A) JP-A-2-110958 (JP, A) JP-A-2-99514 (JP, A) JP-A-2- 99552 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) C08L 63/00-63/10 C08K 3/36 C08G 59/24 H01L 23/29

Claims (1)

(57) [Claims] An epoxy composition comprising an epoxy resin (A), a curing agent (B) and a filler (C),
The epoxy resin (A) has the following general formula (I) (However, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ each represent a hydrogen atom, a halogen atom, or a group selected from an alkyl group having 1 to 4 carbon atoms.) The epoxy resin (a) is contained as an essential component, and the filler (C) comprises 99 to 50% by weight of crushed fused silica having an average particle size of 10 μm or less and 1 to 50% by weight of spherical fused silica having an average particle size of 4 μm or less. An epoxy composition, wherein the average particle size of the spherical fused silica is smaller than the average particle size of the crushed fused silica, and the proportion of the filler (C) is 75 to 90% by weight of the whole.