JPH0299514A - Epoxy based composition having heat resistance to solder - Google Patents

Abstract

PURPOSE:To obtain the title composition containing an epoxy resin having a specific structure, curing agent and fused silica having a specific composition and having excellent heat resistance to solder, reliability and fluidity and useful as a coating, etc. CONSTITUTION:The aimed composition containing (A) an epoxy resin having skeleton expressed by the formula (R<1>-R<8> are H, 1-4C alkyl or halogen), (B) curing agent and (C) fused silica having <=20mum average particle size and consisting of (i) >=40wt.% crushed fused silica having <=12mum average particle size and (ii) <=60-wt.% globular fused silica having <=40mum average particle size.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Field of Application> The present invention relates to a soldering heat resistant epoxy resin composition having excellent soldering heat resistance, reliability and fluidity.

<Conventional technology> Epoxy resins have excellent heat resistance, moisture resistance, electrical properties, adhesive properties, etc., and can be given various properties depending on the formulation, so they are used as industrial materials such as paints, adhesives, and electrical insulation materials. has been done.

For example, as methods for encapsulating electronic circuit components such as semiconductor devices, hermetically sealed seals using metals or ceramics, and resin encapsulation using phenolic resin, silicone resin, epoxy resin, etc., have been proposed, but they are not economical or productive. In view of the balance of physical properties, resin sealing using cresol novolac type epoxy resin has become the main method.

On the other hand, recently, higher density and automation have been promoted in the mounting of components on printed circuit boards, and instead of the conventional "1 insertion mounting method 2" in which lead bins are inserted into holes in the board, components are soldered onto the surface of the board. "Surface mount method" is becoming popular.As a result, packaging is also changing from conventional DI.
There is a shift from the R (dual in-line package) type to the thin PPP (flat plastic package) type, which is suitable for high-density mounting and surface mounting.

With the shift to surface mounting methods, the soldering process, which used to be less of a problem, has become a major issue. In the conventional pin insertion mounting method, the soldering process only partially heats the leads, but in the surface mount method, the entire package is immersed in a heating medium and heated. Methods used include immersion in a solder bath, heating with saturated steam of inert gas (vapor phase method), and infrared reflow method, but in any of these methods, the entire package is heated to a high temperature of 210 to 270 degrees Celsius. . For this reason, when soldering a package sealed with a conventional sealing resin, cracks sometimes occur in the resin part, resulting in a problem that the reliability deteriorates and the package cannot be used as a product.

It is said that the occurrence of cracks in the soldering process is due to moisture absorbed between the post-curing process and the mounting process explosively turning into water vapor and expanding when soldering is heated. A method is used in which the post-cured package is completely dried, stored in a sealed container, and shipped.

Various improvements to the sealing resin are also being studied. For example, a method of blending a rubber component into a sealing resin to reduce internal stress (JP-A-58-219218, JP-A-59-96)
122 Publication), method for selecting the type of inorganic filler (Japanese Patent Application Laid-Open No. 19136-1982, Japanese Patent Application Laid-Open No. 60-20214)
5), a method of making the stress and strain uniform by making the shape of the inorganic filler spherical or controlling the particle size (JP-A-60-171750, JP-A-60
-17937 publication, JP-A-62-74924 publication,
JP-A-62124143, JP-A-62-2091
28, Japanese Patent Publication No. 63-26128), a method of reducing stress generation due to moisture in a soldering bath by reducing water absorption with water-based additives and waxes (Japanese Patent Application Laid-open No. 60-65
023M Publication).

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

In addition, resins improved by various methods are gradually becoming more effective, but they are not sufficient to meet the more severe demands that come with advances in packaging technology. After humidifying a semiconductor device sealed with resin, for example, 85°C/85% RH treatment for 72 hours, or 121°C/2 atm PCT (pressure
(Kutsker test) When immersed in a solder bath after 72 hours of treatment, all resin parts will swell or crack, reducing reliability. In other words, a highly reliable sealing resin that prevents cracks during heating during soldering has not yet been obtained, and there is still a need for a sealing resin that has excellent soldering heat resistance in response to advances in surface mounting technology. The current situation is that development is desired.

Furthermore, Darezol novolak-type epoxy resin, which has traditionally been used for semiconductor encapsulation, has a relatively high viscosity, and its fluidity decreases when small particle size silica is added or when the amount of silica added is increased. There was a problem that molding became difficult.

An object of the present invention is to provide a soldering heat-resistant epoxy resin composition that eliminates the problem of cracks that occur during the soldering process, has high reliability, and has excellent soldering heat resistance and fluidity. The objective is to enable a resin-sealed semiconductor device that can be

Means for Solving the Problems〉 That is, the present invention provides an epoxy resin (^), a hardening agent fB
) and fused silica (C) with an average particle size of 20 IJt1 or less
In the solder heat-resistant resin composition consisting of 70 to 85% by weight, the epoxy resin (A) has the following formula (1) (wherein R1 to R8 represent a hydrogen atom, a lower alkyl group of 01 to C4, or a halogen atom). The fused silica (C) contains 40% by weight or more of crushed fused silica (C') having an average particle size of 12u+n or less and an average particle size of 40
This is a soldering heat-resistant epoxy resin composition consisting of 60% by weight or less of spherical fused silica (C'') having a particle size of .mu.m or less.

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

In the present invention, the epoxy resin (^) is an epoxy resin (8' ) is important to contain as an essential component.

If the epoxy resin (8') is not contained, the effect of preventing cracks in the soldering process will not be exhibited.

In the following formula (0), preferred specific examples of R1-R8 include a hydrogen atom, a methyl group, an ethyl group, a 5ec-butyl group, a tert-butyl group, a chlorine atom, a bromine atom, and the like.

Preferred specific examples of the epoxy resin (A') in the present invention include 4,4'-bis(2,3-epoxypropoxy)biphenyl, 44'-bis(2,3-epoxypropoxy)-3,3', 5.5-tetramethylbiphenyl, 4.4'-bis(2,3-epoxypropoxy)
-3,3', 5.5-tetramethyl-2-talolobiphenyl, 4°4'-bis(2,3-epoxypropoxy)-33', 5.5'-tetramethyl-2-bromobiphenyl, 4,4'-bis(2,3-epoxy-10boxy)-3,3',5.5'-tetraethylbiphenyl, 4
．． 4'-bis(2,3-epoxy 10boxy) 3,
Examples include 3', 5,5'-tetrabutylbiphenyl.

In the present invention, the epoxy resin (A) may contain an epoxy resin other than the epoxy resin (8') in combination with the above-mentioned epoxy resin (A'). Other epoxy resins that can be used in combination include, for example, cresol novolac type epoxy resin, phenol novolata type epoxy resin, novolac type epoxy resin represented by the following formula (where n is an integer of 0 or more), bisphenol A, Examples include various novolac type epoxy resins synthesized from resorcinol and the like, bisphenol A type epoxy resins, linear aliphatic epoxy resins, alicyclic epoxy resins, and polycyclic epoxy resins.

Epoxy resin (A′) contained in epoxy resin (A)
) There is no particular restriction on the ratio of the epoxy resin (A'), and the effect of the present invention can be exhibited as long as the epoxy resin (A') is contained as an essential component. ) is usually contained in the epoxy resin (A) in an amount of 20% by weight or more, preferably 40% by weight or more, particularly preferably 60% by weight or more.

...Tsukuda In the resin composition of the present invention, the amount of epoxy resin (A) blended is usually 3 to 30% by weight, preferably 5 to 25% by weight.

The curing agent (B) in the present invention is an epoxy resin (A
) is not particularly limited as long as it is cured by reacting with the material.

For example, novolac resins such as phenol novolac and cresol novolac, bisphenol compounds such as tetrabromobisphenol A, acid anhydrides such as maleic anhydride, phthalic anhydride, and pyromellitic anhydride, metaphenylene diamine, diaminodiphenylmethane, and diaminodiphenylsulfone. Examples include aromatic amines such as. For encapsulating semiconductor devices, phenol novolak and cresol novolak are preferably used from the viewpoint of heat resistance and storage stability. Depending on the application, two or more types of curing agents may be used together. In the present invention, the amount of curing agent (B) blended is usually 2 to 15
Weight%.

Furthermore, the blending ratio of the epoxy resin (8) and the curing agent (B) should be (B) to (A) from the viewpoint of mechanical properties and moisture resistance.
It is preferable that the chemical equivalent ratio of A diagonal curing catalyst may also be used. 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-methylimidazole, 2
- Imidazoles such as heptadecylimidazole, triethylamine, benzyldimethylamine, α-methylbenzyldimethylamine, 2-(dimethylaminomethyl)phenol, 2.4. , 6-tris(dimethylaminomethyl)phenol, 1,8-diazabicyclo(5,
4,0) Tertiary amines such as undecene-7, organic metals such as zirconium tetramethoxide, zirconium tetrapropoxide, tetrakis(acetylacetonal-nato)zirconium, tri(acetylacetonal-)aluminum, l- Examples include organic phosphine such as liphenylphosphine, triethylbosphine, tributylphosphine, trimethylphosphine, tri(ρ-methylphenyl)bosphine, and tri(nonylphenyl)phosphine. Depending on the application, two or more types of curing catalysts may be used in combination. The amount of curing catalyst added is epoxy resin (A) 1
It is preferably 0.1 to 10 parts by weight per 00 parts by weight.

The fused silica FC) in the present invention has an average particle size of 201J
Fused silica (C) If the average particle size of the crushed fused silica (C') exceeds 20 μm, the average particle size of the crushed fused silica (C') exceeds 12 μm, or the average particle size of the spherical fused silica exceeds 40 μm, the soldering heat resistance will decrease. Preferred average The particle size is 15μm or less for fused silica (C), 10u+n or less for crushed fused silica (C'), and 30μm or less for spherical fused silica (C').Here, the average particle size is the particle whose cumulative weight is 50%. Means the diameter (median diameter).

Furthermore, in the composition of fused silica (C), crushed fused silica (
C') is less than 40% by weight and spherical fused silica (C') is 6
If it exceeds 0% by weight, soldering heat resistance will decrease. Preferably, the amount of crushed fused silica (C') is 60% by weight or more, and the amount of spherical fused silica (C'') is 40% by weight or less.

In the present invention, the blending amount of fused silica (C) is 70 to 85
% by weight, preferably 73-833-83 weight. If it is less than 70% by weight, soldering heat resistance will be insufficient, and if it exceeds 85% by weight, fluidity will decrease and molding will become difficult.

In the present invention, it is preferable to surface-treat the fused silica (C) with a coupling agent such as a silane coupling agent or a titanate coupling agent in advance in terms of moisture resistance and mechanical properties.

The epoxy resin composition of the present invention includes crystalline silica, calcium carbonate, magnesium carbonate, alumina, magnesia,
Fillers such as clay, talc, calcium silicate, titanium oxide, asbestos, and glass fiber, halogen compounds such as halogenated epoxy resin, flame retardants such as phosphorus compounds,
Flame retardant aids such as antimony trioxide, carbon black,
Coloring agents such as iron oxide, silicone oil, elastomers such as modified nitrile rubber, modified polybutadiene rubber, olefin rubber, styrene rubber, silane coupling agents, coupling agents such as titanate coupling agents,
Long chain fatty acids, metal salts of long chain fatty acids, esters of long chain fatty acids, amides of long chain fatty acids, mold release agents such as paraffin wax, and crosslinking agents such as organic peroxides can be optionally added.

The epoxy resin composition of the present invention is preferably melt-kneaded, and a known method can be used for the melt-kneading. For example, using a Banbury mixer, Nigoo, roll, -screw or twin-screw extruder, Coneygoo, etc.,
The resin composition can be prepared at a temperature of 0 to 150°C.

<Example> Hereinafter, the present invention will be specifically explained with reference to Examples.

The numbers in the examples mean parts by weight.

Examples 1 to 9, Comparative Examples 1 to 7 Reagents were triblended using a mixer at the composition ratios shown in Tables 1, 2, and 3. This was heated and kneaded for 5 minutes using a mixing roll with a roll surface temperature of 90° C., then cooled and pulverized to produce a solder heat-resistant epoxy resin composition.

Using this composition, by low pressure transfer molding method,
Don't measure spiral flow. In addition, a 44-pin QFP was molded under the conditions of 175°C x 4 minutes and the simulated element was sealed.
After that, it was post-cured at 175°C for 5 hours. After post-curing, the physical properties of each composition were measured using the following physical property measuring method.

Soldering heat resistance: 24 44-pin QFPs at 85℃, 8
After humidifying at 5% RH for 72 hours, the QFPs were crushed in a solder bath at 250°C for 10 seconds, and the percentage of QFPs without cracks was determined.

Reliability: 44pi subjected to the soldering heat resistance test mentioned above.
Using nQFP, humidification was performed at 121'C1100% RH, and the time required for the bottle failure rate to reach 50% was determined.

These results are shown in Table 3.

As seen in Table 3, the solder heat resistant epoxy resin compositions of the present invention of Examples 1 to 9 have high values of solder heat resistance and reliability, and have a long spiral flow.

On the other hand, as seen in Comparative Examples 1 to 3, if epoxy resin (A'), epoxy resin ■, is not added, the spiral flow becomes short, resulting in unfilling during molding, or when molding is possible. Also, soldering heat resistance and reliability will decrease.

In addition, as seen in Comparative Examples 4 to 7, the average particle size was 121
If crushed fused silica (C') of J11 or less is not added in an amount of 40% by weight or more, the soldering heat resistance and reliability will deteriorate.

<Effects of the Invention> According to the present invention, by adding an epoxy resin with a specific structure, a curing agent, and fused silica with a specific composition, a soldering heat-resistant epoxy resin composition with excellent soldering heat resistance, reliability, and fluidity can be obtained. is obtained.

Patent application Daitoshi Co., Ltd.

Claims (1)

[Claims] Epoxy resin (A), curing agent (B) and average particle size 20
In a solder heat-resistant resin composition comprising 70 to 85% by weight of fused silica (C) of µm or less, the epoxy resin (A
) is the following formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼……(I) (However, R^1 to R^8 are hydrogen atoms, C_1 to C_4
represents a lower alkyl group or a halogen atom. ) contains as an essential component an epoxy resin (A') having a skeleton represented by
A soldering heat-resistant epoxy resin composition comprising 40% by weight or more of crushed fused silica (C') having a particle size of 2 μm or less and 60% by weight or less of spherical fused silica (C″) having an average particle size of 40 μm or less.