JPH0668010B2 - Resin composition for semiconductor encapsulation - Google Patents

Description

The present invention relates to a resin composition for encapsulating a semiconductor device. More specifically, the present invention relates to a resin composition for semiconductor encapsulation, which prevents cracks from being generated in the encapsulating resin during a soldering process when mounting a resin-encapsulated semiconductor device.

<Prior Art> In recent years, the degree of integration of semiconductor devices has been rapidly advanced, and the size of elements and the miniaturization of wiring have been remarkably advanced. Most of the semiconductor devices including these highly integrated semiconductor devices are currently resin-sealed, but this is largely due to the development of a sealing resin having high reliability and excellent performance.

On the other hand, recently, densification and automation have also been promoted in mounting components on a printed circuit board. Instead of the conventional "insertion mounting method" in which lead pins are inserted into holes in the substrate, components are soldered to the surface of the substrate. “Surface mounting method” is becoming popular. Along with that, the package is also the conventional DIP
The (dual in-line package) type is shifting to a thin FPP (flat plastic package) type suitable for high-density mounting and surface mounting.

With the shift to the surface mounting method, the soldering process, which has not been a problem so far, has become a big problem.
In the conventional pin insertion mounting method, the soldering process only partially heats the lead portion, 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, solder bath dipping, heating with saturated vapor of inert gas (vapor phase method), infrared reflow method, etc. are used, but in either method, the entire package is heated to a high temperature of 210 to 270 ° C. It will be heated. Therefore, the conventional package sealed with the sealing resin has a problem that the resin portion is cracked during soldering and cannot be used as a product.

The occurrence of cracks in the soldering process is said to be due to the moisture absorbed between the post-curing process and the mounting process explosively turning into steam and expanding during heating by soldering. A method is used in which the package is completely dried and stored in a sealed container before shipping.

Various improvements have been made to the sealing resin. For example, a method of blending a sealing resin with a rubber component to reduce the internal stress (JP-A-58-219218 and JP-A-59-96).
122), and a method for selecting the type of inorganic filler (Japanese Patent Laid-Open No. 58-19136, Japanese Patent Laid-Open No. 60-20214).
No. 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 and JP-A-6-176750).
No. 0-17937), a method of reducing water absorption by a water-repellent additive or wax, and reducing stress generation due to water in a solder bath (JP-A-60-65023).

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

Further, resins improved by various methods have been gradually effective, but they are not sufficient to meet the more severe demands accompanying the progress of packaging technology. Specifically, after the semiconductor device sealed with the resin obtained by these conventional methods is humidified, for example, 85 ° C./85% RH treatment for 72 hours, or 121 ° C./2 atmospheric pressure PCT (pressure cooker test). ) When 72 hours after the treatment, the resin portion is swollen or cracked when immersed in a solder bath.
That is, a sufficiently satisfactory sealing resin that prevents the occurrence of cracks during soldering heating has not yet been obtained. At present, there is a demand for development of a sealing resin having excellent solder heat resistance, which corresponds to the progress of surface mounting technology.

An object of the present invention is to provide an improved encapsulating resin that solves the problem of cracks that occur during the soldering process, and to enable a resin-encapsulated semiconductor device that can be surface-mounted.

<Means for Solving Problems> That is, according to the present invention, the epoxy resin (A), the curing agent (B), and the powdery filler (C) are used as main components in the resin composition for semiconductor encapsulation. A) is the following formula (I) (However, R _{1 to} R ₈ represent a hydrogen atom, a C _{1 to} C ₄ lower alkyl group or a halogen atom.) As an essential component, the epoxy resin (a) having a skeleton represented by A resin composition for semiconductor encapsulation, wherein the filler (C) contains 50% by weight or more of fine powder particles having a particle diameter of 14 μ or less.

The configuration of the present invention will be described in detail below.

The resin composition for semiconductor encapsulation of the present invention contains an epoxy resin (A), a curing agent (B) and a powdery filler (C) as main components.

The epoxy resin (A) in the present invention has the following formula (I) (However, R _{1 to} R ₈ represent a hydrogen atom, a C _{1 to} C ₄ lower alkyl group or a halogen atom.) It is important to contain an epoxy resin (a) having a skeleton represented by . If the epoxy resin (a) is not contained, the effect of preventing the occurrence of cracks in the soldering process is not exerted.

In the above formula (I), preferred examples of R _{1 to} R ₈ include a hydrogen atom, a methyl group, an ethyl group, a propyl group,
i-propyl group, n-butyl group, sec-butyl group, t
An ert-butyl group, a chlorine atom, a bromine atom and the like can be mentioned.

Preferred specific examples of the epoxy resin (a) in the present invention include 4,4'-bis (2,3-epoxypropoxy) biphenyl, 4,4'-bis (2,3-epoxypropoxy) -3,
3 ', 5,5'-tetramethylbiphenyl, 4,4'-bis (2,3-epoxypropoxy) -3,3', 5,5'-tetramethyl-2-chlorobiphenyl, 4,4'- Bis (2,3-epoxypropoxy) -3,3 ', 5,5'-tetramethyl-2
-Bromobiphenyl, 4,4'-bis (2,3-epoxypropoxy) -3,3 ', 5,5'-tetraethylbiphenyl, 4,
4'-bis (2,3-epoxypropoxy) -3,3 ', 5,5'
-Tetrabutyl biphenyl and the like.

The epoxy resin (A) in the present invention may contain an epoxy resin other than the epoxy resin (a) in combination with the above epoxy resin (a). Other epoxy resins that can be used in combination, for example, cresol novolac type epoxy resin, phenol novolac type epoxy resin, novolac type epoxy resin represented by the following formula (II), (However, n represents an integer of 0 or more.) Various novolac type epoxy resins synthesized from bisphenol A and resorcin, bisphenol A type epoxy resin, linear aliphatic epoxy resin, alicyclic epoxy resin, heterocyclic type Examples thereof include epoxy resin.

Epoxy resin (a) contained in epoxy resin (A)
The ratio of 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 in order to exert a more sufficient effect, the epoxy resin (a) is It is necessary that the content of (A) is usually 10% by weight or more, preferably 20% by weight or more.

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

The curing agent (B) in the present invention is not particularly limited as long as it reacts with an epoxy resin and is cured. For example, phenol novolac resin, cresol novolac resin,
A novolac resin represented by the following formula (III), (However, n represents an integer of 0 or more.) Various novolac resins synthesized from bisphenol A and resorcin, various polyhydric phenol compounds, acid anhydrides such as maleic anhydride, phthalic anhydride, and pyromellitic anhydride, meta Examples thereof include aromatic amines such as phenylenediamine, diaminodiphenylmethane, and diaminodiphenylsulfone, but are not particularly limited.

The content of the curing agent (B) in the resin composition of the present invention is usually 1 to 20% by weight, preferably 2 to 15% by weight.

The epoxy resin (A) and the curing agent (B) used in the present invention are those from which sodium ions, chlorine ions, free acids, alkalis and impurities which may form them are removed as much as possible from the viewpoint of moisture resistance. It is preferable.

The compounding ratio of the epoxy resin (A) and the curing agent (B) may be such that the chemical equivalent ratio of the curing agent to the epoxy resin is 0.5 to 1.5, particularly 0.7 to 1.2 in view of mechanical properties and heat resistance. preferable.

It is essential that the powdery filler (C) in the resin composition of the present invention contains 50% by weight or more of fine powder particles having a particle diameter of 14 μm or less, preferably 12 μm or less, and particularly preferably 10 μm or less. 50% by weight of fine powder particles of 14 μ or less
If it is less than the above, the effect of preventing the occurrence of cracks in the soldering process is not sufficiently exerted.

There is no particular limitation on the material of the powdery filler (C), but usually fused silica, crystalline silica, alumina, silicon nitride, silicon carbide, magnesium carbonate, calcium carbide, clay, talc, calcium silicate, titanium oxide, etc. Is used. These can be used in combination of two or more. Among them, fused silica has a large effect of lowering the coefficient of linear expansion and is effective in reducing stress, and is therefore preferably used.
The particle shape of the powdery filler (C) is not particularly limited, and a crushed shape, a spherical shape, or a combination of crushed and spherical shapes can be used.

The particle size distribution of the powdery filler (C) is not particularly limited as long as the particle size is within the above range. Two or more kinds of powdery fillers having different particle size distributions can be used in combination.

In the resin composition of the present invention, the amount of the powdered filler (C) is usually 50 to 85% by weight, preferably 65 to 80% by weight.
% By weight. If it is less than 50% by weight, the linear expansion coefficient becomes large, and if it exceeds 85% by weight, the moldability is insufficient.

Further, in the present invention, a curing accelerator may be used to accelerate the curing reaction between the epoxy resin and the curing agent. The curing accelerator is not particularly limited as long as it accelerates the curing reaction. For example, imidazoles such as 2-methylimidazole and 2-phenylimidazole, benzyldimethylamine, amines such as 1,8-diazabicyclo (5,4,0) undecene-7 (abbreviated as DBU), triphenylphosphine, tetra Organic phosphorus compounds such as phenylphosphonium tetraphenylborate are preferably used.

The resin composition of the present invention is a rubber-like polymer such as silicone rubber, olefin rubber, diene rubber, a release agent such as wax, a colorant such as carbon black, if necessary,
A coupling agent, a brominated compound, a flame retardant such as antimony oxide, and silicone oil can be used.

The resin composition of the present invention is preferably melt-kneaded, and a known method can be used for melt-kneading. For example, a Banbury mixer, a kneader, a roll, a uniaxial or biaxial extruder, a cokneader and the like can be used for melt kneading.

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

In the examples, parts and% mean parts by weight and% by weight, respectively.

Examples 1 to 15 and Comparative Examples 1 to 19 The raw materials shown in Tables 1 and 2 were blended in the composition ratios shown in Table 3 and dry blended with a mixer. 5 using a mixing roll with a roll surface temperature of 90 ° C
After kneading by heating for 1 minute, the resin composition was manufactured by cooling and pulverizing.

Using a 42 alloy lead frame equipped with these resin compositions and simulated elements, a 44-pin flat package was molded by a low-pressure transfer molding machine under the conditions of 180 ° C. × 2 minutes, and then post-cured at 180 ° C. for 5 hours.

The resulting flat package cured product is 85 ° C, 85% R
After humidifying with H for 72 hours, in a solder bath at 26 ° C, 1
Immersion was carried out for 0 seconds, and the crack generation state after immersion was examined.

The results are shown in Table 3.

In Table 3, the solder heat resistance is shown by the number of packages in which no crack is generated among the 20 packages.

The following is clear from the results of Table 3.

As seen in Examples 1 to 15, the epoxy resin (a) was contained, and the powdery filler was sealed with the resin composition of the present invention containing 50% by weight or more of fine powder particles having a particle diameter of 14 μ or less. The package has almost no cracks even when immersed in a solder bath at 260 ° C. after humidification, and has excellent solder heat resistance.

On the other hand, as seen in Comparative Examples 1 to 5, the powdery filler is 1
Even if the fine powder particles of 4 μm or less are contained in an amount of 50% by weight or more, the resin composition not containing the epoxy resin (a) has cracks in most of the packages.

Even if the epoxy resin (a) is contained as in Comparative Examples 6 to 8, the resin composition in which the powdery filler contains less than 50% by weight of fine powder particles having a particle diameter of 14 μ or less is present in most packages. Cracks occur.

As seen in Comparative Example 9, the epoxy resin (a) was not contained, and the powdery filler contained fine powder particles having a particle diameter of 14 μm or less.
A resin composition containing less than 0% by weight causes cracks in all packages.

<Effects of the Invention> The resin composition of the present invention has extremely excellent solder heat resistance, and by encapsulating with the resin composition of the present invention, generation of resin cracks in the soldering step when mounting a semiconductor device is prevented. can do. Taking advantage of this feature,
It is expected to be applied to various applications such as encapsulation of semiconductor devices for surface mounting.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A 61-98726 (JP, A) JP-A 61-47725 (JP, A) JP-A 60-17937 (JP, A) JP-A 62- 261161 (JP, A)

Claims (1)

[Claims] 1. In a resin composition for semiconductor encapsulation containing an epoxy resin (A), a curing agent (B) and a powdery filler (C) as main components, the epoxy resin (A) is represented by the following formula (I): (However, R _{1 to} R ₈ represent a hydrogen atom, a C _{1 to} C ₄ lower alkyl group or a halogen atom.) The epoxy resin (a) having a skeleton represented by A resin composition for semiconductor encapsulation, wherein the filler (C) contains 50% by weight or more of fine powder particles having a particle diameter of 14 μ or less.