JPH04264155A - Epoxy resin composition for semiconductor sealing - Google Patents

Abstract

PURPOSE:To obtain the title composition excellent in soldering-heat resistance, flame retardancy and high-temperature reliability by mixing a specified epoxy resin with a specified amount of a filler, a specified amount of hydrotalcite compound, a curing agent, a Br compound and an Sb compound. CONSTITUTION:This composition comprises an epoxy resin essentially consisting of an epoxy resin of the formula (wherein two of R<1> to R<8> are each a glycidyl ether group, and the other are each H, halogen or 1-4C alkyl), a curing agent (e.g. phenolic novolac resin), 75-95wt.%, based on the total composition, filler (e.g. fused silica), 0.01-10wt.%, based on the total composition, hydrotalcite compound [e.g. Mg4.5Al2(OH)13CO3.3.5 H2O], a Br compound (e.g. brominated bisphenol A epoxy resin),and an Sb compound (e.g. Sb2O3).

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 for encapsulating semiconductors which has excellent soldering heat resistance, flame retardancy and high temperature reliability.

0002

[Prior art] 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 a sealing method for electronic circuit components such as semiconductor devices, hermetic seals using metals and ceramics, phenolic resins, silicone resins,
Resin sealing using epoxy resin or the like has been proposed. However, from the viewpoint of economy, productivity, and balance of physical properties, resin sealing using 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 "insertion mounting method" in which lead pins are inserted into holes in the board, components are soldered onto the surface of the board. The "surface mount method" for attaching devices has become popular. Along with this, the packaging has changed from the conventional DI.
There is a shift from P (dual in-line package) to thin FPP (flat plastic package), which is suitable for high-density packaging and surface mounting.

[0005] With the transition to the surface mounting method, the soldering process, which had not been a problem in the past, has become a big problem. In the conventional pin insertion mounting method, only the leads are partially heated during the soldering process, but in the surface mounting method, the entire package is immersed in a heating medium and heated. Soldering methods for surface mounting methods include immersion in a solder bath and heating with saturated vapor of inert gas (vapor phase method).
or an infrared reflow method, but in either method the entire package is heated to a high temperature of 210 to 270°C. For this reason, packages sealed with conventional sealing resin have the problem that cracks occur in the resin portion during soldering, reducing reliability and making the package unusable as a product.

[0006] The occurrence of cracks in the soldering process is
This is said to be caused by the moisture absorbed between post-curing and the mounting process becoming explosively vaporized and expanding during soldering heat.As a countermeasure, the post-cured package is completely dried and sealed in a container. The method used is to store and ship the product.

Various improvements in sealing resins have also been studied. For example, a method of adding an epoxy resin having a naphthalene skeleton to reduce the stress of the resin (Japanese Patent Application Laid-Open No. 2-886
No. 21, JP-A-2-110958), etc.

Furthermore, in order to improve the moisture resistance of the sealing resin, a hydrotalcite compound was added (Japanese Patent Laid-Open No. 61-1
No. 9625) has been proposed.

On the other hand, electronic components such as semiconductors are required to be flame retardant according to UL standards, and for this reason, flame retardants such as bromine compounds and antimony compounds are usually added to sealing resins. .

0010

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 high.

[0011] In addition, resins that have been improved by various methods are gradually producing effects, but they are still not sufficient. Adding an epoxy resin with a naphthalene skeleton,
Method for achieving low stress in resin (Japanese Patent Application Laid-Open No. 2-88621
JP-A-2-110958) is effective in preventing cracks in the resin portion during soldering, but has the problem of reduced reliability at high temperatures.

On the other hand, reliability at high temperatures is 150 to 200°C.
It guarantees the functionality of semiconductors in high-temperature environments, and is essential for semiconductors that generate a large amount of heat and semiconductors used around automobile engines.

It has been found that the problem with high temperature reliability of epoxy resins having a naphthalene skeleton is mainly caused by flame retardants such as bromine compounds and antimony compounds added to impart flame retardancy. For this reason, an epoxy resin composition for semiconductor encapsulation that is excellent in all of solder heat resistance, flame retardance, and high-temperature reliability has not been obtained.

The object of the present invention is to solve the problem of cracks that occur in the soldering process, and to prevent the reliability from decreasing at high temperatures due to the addition of flame retardants, that is, to improve soldering heat resistance, flame retardance, and high-temperature reliability. An object of the present invention is to provide an excellent epoxy resin composition for encapsulating semiconductors.

[0015]

[Means for Solving the Problems] The present inventors have achieved the above-mentioned problems by adding a hydrotalcite-based compound to an epoxy resin having a naphthalene skeleton, and have created an epoxy resin for semiconductor encapsulation that meets the purpose. It was discovered that a composition can be obtained, and the present invention was achieved.

That is, the present invention provides epoxy resin (A)
, a curing agent (B), a filler (C), a hydrotalcite compound (D), a bromine compound (E), and an antimony compound (F), the resin composition comprising the epoxy resin (A). ) is the following formula (I)

[0017]

[Case 2]

Epoxy resin represented by (wherein, two of R1 to R8 represent a glycidyl ether group, and the others represent a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms) (a) as an essential component, the proportion of the filler (C) is 75 to 95% by weight of the whole, and the proportion of the hydrotalcite compound (D) is 0.01 to 10% by weight of the whole. The present invention provides an epoxy resin composition for semiconductor encapsulation.

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

It is important that the epoxy resin (A) in the present invention contains the epoxy resin (a) represented by the above formula (I) as an essential component. If the epoxy resin (a) is not contained, the effect of preventing crack generation and the heat resistance effect in the soldering process will not be exhibited. The above formula (I
), preferred specific examples of R1 to R8 are:
Hydrogen atom, methyl group, ethyl group, propyl group, i-propyl group, n-butyl group, sec-butyl group, tert-
Examples include butyl group, chlorine atom, bromine atom, etc.

Preferred specific examples of the epoxy resin (a) in the present invention include 1,5-diglycidylnaphthalene, 1,5-diglycidyl-7-methylnaphthalene, 1,
6-diglycidylnaphthalene, 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-di Examples include glycidylnaphthalene.

The epoxy resin (A) in the present invention may contain, in addition to the above-mentioned epoxy resin (a), other epoxy resins in addition to the epoxy resin (a). Other epoxy resins that can be used in combination include, for example, cresol novolak epoxy resins, phenol novolac epoxy resins, biphenyl epoxy resins, various novolac epoxy resins synthesized from bisphenol A and resorcinol, and bisphenol A. Examples include type epoxy resins, linear aliphatic epoxy resins, alicyclic epoxy resins, heterocyclic epoxy resins, and halogenated epoxy resins.

There is no particular restriction on the proportion of the epoxy resin (a) contained in the epoxy resin (A), and the effects of the present invention can be exhibited as long as the epoxy resin (a) is contained as an essential component. In order to exhibit a sufficient effect, epoxy resin (a) is usually mixed into epoxy resin (A) by 5%.
It is necessary to contain 0% by weight or more, preferably 70% by weight or more.

In the present invention, the blending amount of the epoxy resin (A) is usually 4 to 20% by weight, preferably 6 to 18% by weight.
It is.

The curing agent (B) in the present invention is not particularly limited as long as it can be cured by reacting with the epoxy resin (A), and specific examples thereof include phenol novolak resin, cresol novolak resin, bisphenol -Various novolak resins synthesized from Sol A and resorcinol, various polyhydric phenol compounds, acid anhydrides such as maleic anhydride, phthalic anhydride, and pyromellitic anhydride, metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, etc. Examples include aromatic amines. For semiconductor encapsulation, phenolic curing agents are preferably used from the viewpoint of heat resistance, moisture resistance, and storage stability, and two or more types of curing agents may be used in combination depending on the application.

In the present invention, the amount of the curing agent (B) is usually 2 to 15% by weight, preferably 3 to 10% by weight. Furthermore, the compounding ratio of the epoxy resin (A) and the curing agent (B) should be such that the chemical equivalent ratio of (B) to (A) is 0.7 to 1.3, especially 0. .8~1
．． It is preferable that it is in the range of 2.

[0027] Furthermore, in the present invention, epoxy resin (A)
A curing catalyst may be used to promote the curing reaction of and curing agent (B). The curing catalyst is not particularly limited as long as it promotes the curing reaction, and examples include 2-methylimidazole and 2-methylimidazole.
, 4-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, imidazole compounds such as 2-heptadecyl imidazole, triethylamine,
Benzyldimethylamine, α-methylbenzyldimethylamine, 2-(dimethylaminomethyl)phenol, 2
, 4,6-tris(dimethylaminomethyl)phenol, 1,8-diazabicyclo(5,4,0)undecene-
Tertiary amine compounds such as 7, zirconium tetramethoxide, zirconium tetrapropoxide, tetrakis (
Organometallic compounds such as acetylacetonato)zirconium, tri(acetylacetonato)aluminum, and organic compounds such as triphenylphosphine, trimethylphosphine, triethylphosphine, tributylphosphine, tri(p-methylphenyl)phosphine, tri(nonylphenyl)phosphine, etc. Examples include phosphine compounds. Among them, from the viewpoint of moisture resistance, organic phosphine compounds are preferred, and triphenylphosphine is particularly preferably used. Two or more of these curing catalysts may be used in combination depending on the application, and the amount added is preferably in the range of 0.5 to 5 parts by weight per 100 parts by weight of the epoxy resin (A).

Fillers (C) in the present invention include fused silica (G), crystalline silica, silicon nitride, silicon carbide, calcium carbonate, magnesium carbonate, alumina, magnesia, clay, talc, calcium silicate, and titanium oxide. , asbestos, glass fiber, etc. can be added. Among them, fused silica (G) is preferably used from the viewpoint of low stress properties.

Here, fused silica (G) has a true specific gravity of 2.3
It means the following amorphous silica. Its production does not necessarily have to go through a molten state, and any production method can be used. Examples include a method of melting crystalline silica and a method of synthesizing it from various raw materials.

The shape and particle size of the fused silica (G) are not particularly limited, but it consists of 99-50% by weight of crushed fused silica with an average particle size of 10 μm or less and 1-50% by weight of spherical fused silica with an average particle size of 40 μm or less. Fused silica (G) is preferably used because it has a large effect of improving soldering heat resistance and has good fluidity. Among them, the average particle size is 10 μm or less, especially 3
99-50% by weight, especially 99-70% by weight of crushed fused silica with a particle diameter of 1 to 10 μm, and 1 to 50% by weight, especially 1 to 30% by weight of spherical fused silica with an average particle size of 4 μm or less, especially 0.1 μm to 4 μm. Fused silica (G), in which the average particle size of spherical fused silica is smaller than the average particle size of crushed fused silica, particularly 1/2 or less, is most preferably used. Here, the average particle size is the particle size at which the cumulative weight is 50% (
When two or more types of crushed or spherical fused silica with different average particle sizes are used together, it means the average particle size of the crushed or spherical fused silica of the mixture.

In the present invention, the proportion of filler (C) is:
75 to 95% by weight of the total from the viewpoint of formability and low stress properties
It is. When fused silica (G) is used as the filler (C), its proportion is preferably 75 to 90% by weight of the total,
Particularly preferred is 75-88% by weight.

The hydrotalcite compound (D) in the present invention is a composite metal compound represented by the following formula (II) or (III).

Mgx Aly (OH)2x+3y-nzAz
・mH2 O ‥‥‥(II) Mgx Aly
O(2x+3y)/2
‥‥‥(III) (However, A is a functional group capable of generating an n-valent anion An-, n is an integer of 1 to 3,
x, y and z are 0<y/x≦1, 0≦z/y<1.5
m represents 0 or a positive number, and m represents 0 or a positive number. ).

In the above formula (II), preferred specific examples of the n-valent anion An- that can be generated from the functional group A include F-, Cl-, Br-, I-, OH-,
HCO3 − , CH3 COO− , HCOO− ,
CO3 2-, SO4 2-, (COO-)2, tartrate ion [CH(OH)COO-]2, citrate ion [C(OH)COO-](CH2 COO-
)2, salicylate ion C6 H4 (OH)COO
- and so on. Among these, CO3 2- is particularly preferred.

The hydrotalcite compound (D) represented by the above formula (III) is, for example, a hydrotalcite compound (D) represented by the above formula (II),
Manufactured by firing at 900°C.

[0036] As a preferable example of the hydrotalcite compound (D), Mg4.5 Al2 (OH)13
CO3 ・3.5H2 O, Mg4.5 Al2 (O
H)13CO3, Mg5 Al1.5 (OH)13
CO3 ・3.5H2 O, Mg5 Al1.5 (O
H)13CO3, Mg6Al2(OH)16CO
3 ・4H2 O, Mg6 Al2 (OH)16CO
3, Mg0.65Al0.35O1.175, Mg
0.7 Al0.3 O1.15, Mg0.75Al0
．． 25O1.125, Mg0.8 Al0.2 O1
．． 1 etc.

In the present invention, the amount of the hydrotalcite compound (D) added is 0.01 to 10% by weight, preferably 0.02 to 5% by weight, particularly preferably 0.05 to 5% by weight.
It is 2% by weight. If the amount added is less than 0.01% by weight, the effect of improving high temperature reliability will be insufficient, and if it exceeds 10% by weight, the soldering heat resistance will decrease.

The bromine compound (E) and antimony compound (F) in the present invention are usually added as flame retardants to the epoxy resin composition for semiconductor encapsulation, and are not particularly limited, and known compounds can be used.

Preferred specific examples of the bromine compound (E) include brominated epoxy resins such as brominated bisphenol A type epoxy resins, brominated phenol novolak type epoxy resins, brominated polycarbonate resins, brominated polystyrene resins, and brominated polyphenylene resins. Examples include oxide resins, tetrabromobisphenol A, decabromodiphenyl ether, etc. Among them, brominated epoxy resins such as brominated bisphenol A type epoxy resins and brominated phenol novolac type epoxy resins are particularly preferably used from the viewpoint of moldability. It will be done.

The amount of the bromine compound (E) added is preferably 0.1 to 5% by weight of the total amount in terms of bromine atoms from the viewpoint of flame retardancy and high temperature reliability. Particularly preferred is 0.2 to 2% by weight.

A preferred example of the antimony compound (F) is antimony trioxide. The amount of antimony compound (F) added is preferably 0.1 to 10% by weight based on the total weight from the viewpoint of flame retardancy and high temperature reliability. Particularly preferably, it is 0.2 to 4% by weight.

In the present invention, it is preferable from the viewpoint of reliability that the filler (C) is previously surface-treated with a coupling agent such as a silane coupling agent or a titanate coupling agent. As the coupling agent, silane coupling agents such as epoxysilane, aminosilane, and mercaptosilane are preferably used.

The epoxy resin composition for semiconductor encapsulation of the present invention contains colorants such as carbon black and iron oxide, silicone rubber, modified nitrile rubber, modified polybutadiene rubber,
Elastomers such as styrenic block copolymers, thermoplastic resins such as polyethylene, 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 organic polymers. Crosslinking agents such as oxides can optionally be added.

The epoxy resin composition for semiconductor encapsulation of the present invention is preferably melt-kneaded, for example, using a known kneading method such as a Banbury mixer, kneader, roll, single- or twin-screw extruder, or co-kneader. Manufactured by kneading.

[0045]

[Examples] The present invention will be specifically explained below with reference to Examples.

Examples 1 to 9, Comparative Examples 1 to 6 Using the fused silica (G) shown in Table 1, the raw materials were dry blended in a mixer according to the formulation shown in Table 2. This was melt-kneaded using a twin-screw extruder with a barrel temperature set at 90° C., then cooled and pulverized to produce an epoxy resin composition for semiconductor encapsulation.

[0047]

[Table 1]

[0048]

[Table 2]

Using this composition, molding was performed at 175°C for 2 minutes using a low-pressure transfer molding method, followed by molding at 180°C for 2 minutes.
After post-curing for 5 hours, the physical properties and moldability of each composition were measured using the following physical property measuring method.

[0050] Soldering heat resistance: 20 64-pin QFPs equipped with simulated elements with Al vapor deposited on the surface were molded, post-cured, humidified at 85°C/85%RH for 72 hours, and then heated at 250°C.
The QFP was immersed in a heated solder bath for 10 seconds, and QFPs with cracks were judged to be defective.

Flame retardancy: A 5" x 1/2" x 1/16" combustion test piece was molded and post-cured, and flame retardance was evaluated according to UL94 standard.

[0052] High temperature reliability: 64pi after soldering heat resistance evaluation
Using nQFP, high-temperature reliability was evaluated at 175° C., and the time required for the cumulative failure rate to reach 50% was determined, which was defined as the high-temperature life.

[0053] These results are shown in Table 3.

[0054]

[Table 3]

As seen in Table 3, the epoxy resin compositions for semiconductor encapsulation of the present invention (Examples 1 to 9) are excellent in solder heat resistance, flame retardancy, and high temperature reliability. Among them, Example 4 in which fused silica (G) with a specific shape and particle size was blended.
Samples 9 to 9 are particularly excellent in terms of solder heat resistance failure rate of 15% or less.

On the other hand, in Comparative Example 1, which does not contain epoxy resin (a), the soldering heat resistance is poor and the bromine compound (E)
And/or Comparative Examples 2 to 4 that do not contain the antimony compound (F) have poor flame retardancy.

[0057] Additionally, hydrotalcite compound (D)
Comparative Example 5, which does not contain , has poor high-temperature reliability.

Furthermore, in Comparative Example 6, where the content of fused silica (G) blended as the filler (C) was outside the scope of the present invention, the soldering heat resistance was poor.

[0059]

Effects of the Invention The epoxy resin composition for semiconductor encapsulation of the present invention has excellent soldering heat resistance and difficulty, since it contains a specific epoxy resin, a curing agent, a filler, a hydrotalcite compound, a bromine compound, and an antimony compound. Excellent flammability and high temperature reliability.

Claims (3)

[Claims] Claim 1: Epoxy resin (A), curing agent (B),
A resin composition comprising a filler (C), a hydrotalcite compound (D), a bromine compound (E), and an antimony compound (F), wherein the epoxy resin (A) has the following formula (I). Epoxy represented by [Formula 1] (wherein, two of R1 to R8 represent a glycidyl ether group, and the others represent a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms) Contains resin (a) as an essential component, and contains the filler (C
) is 75 to 95% by weight of the whole, and the proportion of the hydrotalcite compound (D) is 0.01 to 95% of the whole.
An epoxy resin composition for semiconductor encapsulation having a content of 10% by weight. [Claim 2] The filler (C) is fused silica (G),
Claim (1) The proportion thereof is 75 to 90% by weight of the whole.
The epoxy resin composition for semiconductor encapsulation described above. [Claim 3] Fused silica (G) has an average particle size of 10 μm.
The following crushed fused silica 99-50% by weight and average particle size 40
The epoxy resin composition for semiconductor encapsulation according to claim 1, comprising 1 to 50% by weight of spherical fused silica having a particle size of 1 to 5 μm.