JPH03210325A - Semiconductor sealing epoxy resin molding material - Google Patents

Abstract

PURPOSE:To obtain the title material excellent in moldability and humidity resistance by mixing an epoxy resin with a phenolic compound, a reaction product of one of the above components with a reactive silicone oil, a solid silicone polymer, a specified silane coupling agent and an inorganic filler. CONSTITUTION:The title material is obtained by mixing an epoxy resin (A) having at least two epoxy groups in the molecule with a compound (B) having at least two phenolic hydroxyl groups in the molecule, a reaction product (C) of component A or component B with a reactive silicone oil, a solid silicone polymer (D) of a max. particle diameter of 150mum or below and a hardness of 80 or below, a ureido-containing silane coupling agent (E) and an inorganic filler (F) as essential components. When a semiconductor component is sealed with this molding material, a product of improved humidity resistance and high reliability can be obtained in good moldability without staining the mold.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an epoxy resin molding material for semiconductor encapsulation that has excellent moldability and moisture resistance.

[Prior art]

Epoxy resins are widely used as various molding materials because they have superior electrical properties, mechanical properties, heat resistance, adhesive properties, water resistance, etc. compared to other thermosetting resins. Particularly recently, it has attracted attention as a molding material for semiconductor encapsulation.

In recent years, in the semiconductor field, the integration of semiconductor elements has been increasing year by year, and with this, there has been a noticeable trend towards finer wiring and larger element sizes. On the other hand, packages that protect semiconductor elements from the external environment are increasingly becoming smaller and larger in size from the viewpoint of high-density mounting on printed circuit boards. Resin-sealed semiconductor devices, in which such large elements are encapsulated in small, thin packages, are prone to failures such as aluminum wiring deformation, passivation cracks, and package cracks.One solution to this problem is to reduce the stress of the encapsulation molding material. has been strongly sought after.

In order to reduce the stress of the molding material for sealing, studies have been conducted on methods of adding and mixing various rubber components to lower the modulus of elasticity. As a result, epoxy resin molding materials to which silicone oil is added are now widely used. Since silicone oil is incompatible with the epoxy resin and curing agent that are the base resin of the molding material, fine particles are dispersed in the base resin (seabird structure), making it possible to lower the elastic modulus while maintaining heat resistance.

However, with the above-mentioned molding materials that are simply blended with silicone, the silicone and base resin phase separate during molding, and the silicone tends to bleed, which tends to cause mold stains and other problems.As a solution to this problem, On the reed,
A method of pre-reacting silicone and base resin has been proposed, and good results have been obtained (for example,
Special Publication No. 62-36050, Special Publication No. 63-3280
Publication No. 7).

[Problem to be solved by the invention]

As mentioned above, if a method is adopted in which silicone is pre-reacted with the base resin and silicone is fixed to the base resin, moldability such as mold stains can be improved, but the problem is that moisture resistance is insufficient. The present invention provides an epoxy resin molding material for semiconductor encapsulation that has improved ITM properties without impairing moldability.

[Means to solve the problem]

As a result of extensive studies to solve the above problems, the present inventors discovered that the following molding materials are effective.
The present invention has now been completed.

That is, the present invention provides: (A) an epoxy resin having 2 (111 or more epoxy groups in one molecule) (B) a compound having 2i11 or more phenolic hydroxyl groups in one molecule (C) the above (A) component or CB) A reaction product of the component and reactive silicone oil, (D) 8 A solid silicone polymer with a large particle size of 150 μm or less and a hardness of 80 or less (E) A ureido group-containing silane coupling agent (F) An inorganic filler as an essential component The present invention provides an epoxy resin molding material for semiconductor encapsulation characterized by the following.

26 in one molecule of component (A) used in the present invention.
As the epoxy resin having an epoxy group of I1 or more,
Epoxy resin molding materials for semiconductors - There are no restrictions as long as they are commonly used, and epoxidized phenol and aldehyde novolac resins such as phenol novolac type epoxy resins and orthocresol novolac type epoxy resins can be used. things, bisphenol A,
Glycidyl ester type epoxy resin obtained by reacting diglycidyl ethers such as bisphenol B, bisphenol F, and bisphenol S, polybases such as phthalic acid and dimer acid with epichlorohydrin, and reaction of polyamines such as diaminodiphenylmethane and isocyanuric acid with epichlorohydrin. The glycidylamine type epoxy resin obtained in There are linear aliphatic epoxy resins and alicyclic epoxy resins obtained by oxidation with peracids such as acids, but from the viewpoint of heat resistance, the epoxy equivalent is 22
A novolac type epoxy resin having a molecular weight of 0 or less is preferred.

21 in one molecule of component (B) used in the present invention.
! Compounds having one or more phenolic hydroxyl groups include phenol, cresol, xylenol, resorcinol, catechol, bisphenol A, and bisphenol F.
There are novolak type phenol resins obtained by condensation reaction of phenols such as and aldehydes under an acidic catalyst, bisphenol A, bisphenol F, polyvarabinyl phenol resins, and polyhydric phenols such as resorcinol, catechol, and hydroquinone. They can be used alone or in combination of two or more types, but from the point of view of cost and balance of properties, novolak type phenol resins are preferred, and the number average molecular weight is preferably 300 to 600. If the number average molecular weight is less than 300, the heat resistance is insufficient, and 6
This is because if it exceeds 00, the fluidity of the molding material decreases.

Next, component (C) used in the present invention is a reaction product of component (A) or component (B) and reactive silicone oil, and the functional group of the reactive silicone oil is (A
There is no particular restriction as long as it is a functional group that can react with the epoxy group in component () or the phenolic hydroxyl group in component (B). −
Such silicone oils have a basic structure of dimethyl silicone and have functional groups such as amino groups, carboxyl groups, mercapto groups, hydroxyphenyl groups, epoxy groups, and alkoxy groups at the terminals and/or side chains of this molecule. Furthermore, in order to improve the compatibility with components (A) and (B), some of the methyl groups are phenyl groups,
As a method for synthesizing the zero reactant, which may have a structure substituted with a 2-phenylethyl group, 2-phenylpropyl group, polyoxyalkylene group, etc., conventionally known catalysts can be used depending on the selected functional group. This can be carried out by heating and stirring a mixture of component (A) or component (B) and reactive silicone oil in the presence or absence of a solvent. Suitable solvents include methyl isobutyl ketone, toluene, xylene, dioxane, and the like. The reaction time varies depending on the concentration of functional groups in the reaction system, solubility, and reaction temperature, but is 1 to 50 hours.

When synthesizing component (C), it is important to control the amount of functional groups in the reactive silicone oil so that some of the epoxy groups or phenolic hydroxyl groups that are functional groups in component (A) or (B) remain. It's about adjusting. That is, when the number of epoxy groups or phenolic hydroxyl groups is 100, it is preferable to mix and carry out the synthesis reaction so that the number of functional groups in the silicone oil is 50 or less. By using component (C) synthesized under such conditions, when the molding material is cured in the mold, component (A), component CB), (
C) The component hardens uniformly, and the silicone as a flexible agent
Uniformly dispersed and quantified in the cured resin.

In addition, the (A) component and the CB) component used in the synthesis of the (C) component are, for the reasons stated above, a novolak type epoxy resin with an epoxy rating of 220 or less as the (A) component, and (B)
As a component, a novolak type phenol resin having a number average molecular weight of 300 to 600 is particularly preferable.The amount of component (C) added is 5 to 7 with respect to the total amount of (A) + (B) + (C).
The content is preferably in the range of 5% by weight; if it is less than 5% by weight, sufficient low stress properties cannot be obtained, and if it exceeds 75% by weight, the mechanical strength of the cured product will decrease. Above (A)
The blending amount of components (B) and (C) is (total number of epoxy groups)/(total number of phenolic water groups) in the tertiary component.
In order to obtain a well-balanced cured product, it is preferable to mix so that the ratio is 0.8 to 1.2.

The solid silicone polymer as component (D) used in the present invention is:
The maximum particle size must be 150 μm or less and the hardness must be 80 or less. The hardness here refers to the Japan Rubber Association standard 5R.
The reason for specifying the maximum particle size as 150 μm or less, which is a value measured with a C-type hardness tester according to IS-0101, is to prevent mold gate clogging during molding. The gate size of a mold for molding a resin-sealed semiconductor device has become smaller as packages become smaller and thinner, and is currently about 200 to 500 μm. Therefore, in order to prevent molding problems such as gate clogging, the maximum particle size must be 150 μm or less. Next, regarding hardness, when using a material with a hardness of over 80, the effect of improving moisture resistance has been observed. 80
It is necessary to do the following. Specific examples of component (D) include:
Examples include polyorganosiloxane polymers such as polydimethylsiloxane, polymethylphenylsiloxane, and dimethylsiloxane-diphenylsiloxane copolymer. Furthermore, crosslinked products of these polyorganosiloxane polymers may be used.Furthermore, functional groups such as silanol groups, hydroxyl groups, carboxyl groups, vinyl groups, amino groups, mercapto groups, engineered boxy groups, and alkoxy groups may be used in the structure. The amount of component (D) to be added is (A)
+ (B) + (C) It is preferably 2 to 10% by weight based on the total amount of component. If it is less than 2% by weight, there is no effect of improving moisture resistance, and if it exceeds 10% by weight, the effect of improving moisture resistance tends to be saturated. This is also because mechanical strength is reduced.

The ureido group-containing silane coupling agent (E) used in the present invention is a compound represented by the following formula.

X3 Si RN)-ICONHz Here, X is a hydrolyzable group such as a methoxy group or an ethoxy group, and R is a lower alkylene group such as a trimethylene group. Such compounds are generally commercially available, for example A-
1160 (manufactured by Nippon Unicar), AY43-031 (manufactured by Toray Silicone), and the like.

Next, the inorganic filler (F) component used in the present invention is an essential component for lowering the linear expansion coefficient of the cured product, and includes, for example, fused silica, crystalline silica, alumina, zircon, calcium silicate, calcium carbonate, silicon carbide, silicon nitride,
Examples include powders such as boron nitride, beryllia, magnesia, zirconia, mullite, and titania, single crystal fibers such as silicon carbide, silicon nitride, and alumina, and glass fibers, but from the viewpoint of cost and balance of properties, fused silica is preferable. In addition, regarding the shape of the filler, both prismatic and spherical shapes can be used. A spherical filler is preferably used as part or all of the filler in order to provide high fluidity. The blending amount of component (F) is preferably 50 to 85% by volume of the entire molding material. If it is less than 50% by volume, the linear expansion coefficient of the cured product becomes large and the package cracking property is poor. Moreover, if it exceeds 85% by volume, the fluidity will be extremely reduced and molding will not be possible under commonly used molding pressures.

The molding material of the present invention may contain a curing accelerator that accelerates the curing reaction between the epoxy resin and the compound having a phenolic hydroxyl group. Examples of the curing accelerator include 1,8-diaza-bicyclo(5,4,O)undecene-7, benzyldimethylamine, triethanolamine, dimethylaminoethanol, 1-lyethylenediamine, tris(dimethylaminomethyl)phenol. Tertiary amines such as 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2
- Heptadecylimidazoldazoles, tributylphosphine, methyldiphenylphosphine, triphenylphosphine, diphenylphosphine, organic phosphines such as phenylphosphine, tetraphenylphosphonium tetraphenylborate, triphenylphosphine tetraphenylborate, 2-ethyl-4-methyl Examples include tetraphenylboron salts such as imidazole tetraphenylborate and N-methylmorpholinetetraphenylborate.

In addition, the molding material of the present invention may contain a flame retardant such as antimony dioxide, a higher III fatty acid, a higher fatty acid metal salt, a mold release agent such as an ester wax, and a coloring agent such as carbon black, if necessary. be able to.

A general method for producing molding materials using the above raw materials is to thoroughly mix a raw material mixture of a predetermined amount using a mixer, etc., then knead it using a heated roll, extruder, etc., cool it, and crush it. A molding material can be obtained by this process.

The most common method for encapsulating a semiconductor using the molding material obtained in the present invention is low-pressure transfer molding, but methods such as injection molding and casting can also be used.

〔Example〕

EXAMPLES The present invention will be explained below with reference to Examples, but the scope of the present invention is not limited to these Examples.

Example 1 Orthocresol novolac type epoxy tree a (epoxy resin A,') with epoxy equivalent weight 200 and softening point 76°C 50
Parts by weight, epoxy equivalent 400, softening point 69°C, bromine content 48% by weight brominated bisphenol A epoxy resin (epoxy resin n1z) 20 parts by weight, hydroxyl equivalent 106,
48 parts by weight of a phenol novolak resin (curing agent B+) with a softening point of 82°C and a number average molecular weight of 450, a dimethyl silicone oil having 2-carboxylethyl groups at both ends and an average degree of polymerization of 100, and the above epoxy resin AI were mixed into 1 - in the presence of liphenylphosphine, weight ratio 10/30 (official f
Compound obtained by reacting with li group M ratio 1.8/100) (
Reactant C,) 40 parts by weight, maximum particle size 105 μm, hardness 5
5 parts by weight of powdered silicone No. 6 (solid silicone D□), 1.3 parts by weight of triphenylphosphine, 1.5 parts by weight of carnauba wax, 8 parts by weight of antimony dioxide, 1.5 parts by weight of carbon black, 3-ureidopropyl 4 parts by weight of triethoxysilane and 450 parts by weight of fused silica were blended together using a 10 inch diameter heating roll.

The mixture was kneaded at a mixing temperature of 80 to 90°C and a mixing time of 10 minutes. A molding material was prepared by cooling and pulverizing the sheet-like mixed wire material.

Example 2 The solid silicone DI5 heavy claw part of Example 1 was prepared with a maximum particle size of 4.
It was produced in the same manner as in Example 1 except that 5 parts by weight of powdered silicone (solid silicone D2) having a diameter of 4 μm and a hardness of 41 was used instead.

Example 3 Reactant c+40 parts by weight of Example 1 was mixed with dimethyl silicone oil having glycidoxyprobyl groups at both ends and having an average degree of polymerization of 30, and the curing agent B1 described in Example 1, into triphenylphosphine. Compound (reactant C,) obtained by reacting in the presence of at a weight ratio of 10/15 (functional group ratio 5.8/100) 25! In the iX section, epoxy l! 1 fat A1
50 parts] to 80 parts by weight, and further, curing agent B, 48 parts by weight.
It was produced in the same manner as in Example 1 except that the weight part was changed to 33 parts by weight.

Example 4 A molding material was produced in the same manner as in Example 3, except that 5 parts by weight of solid silicone Dt in Example 3 was replaced with 5 parts by weight of solid silicone D used in Example 2.

Comparative Example 1 Example 1 except that solid silicone D of Example 1 was removed.
A molding material was prepared in the same manner.

Comparative Example 2 3-ureidopropyltriethoxysilane 4 of Example 1
A molding material was prepared in the same manner as in Example 1, except that the weight part was replaced with 4 tffi parts of 3-glycidoxypropyltrimethoxysilane.

Comparative Example 3 Same as Example 1 except that solid silicone D1 of Example 1 was removed and 4 parts by weight of 3-ureidopropyltriethoxysilane was replaced with 4 parts by weight of 3-glycidoxypropyltrimethoxysilane. A molding material was prepared.

Next, using the molding material obtained above, 6I1wII
Transfer molding of 54-pin QFP equipped with X6im test element (molding temperature 175℃, molding pressure cuff 0k
g/mm”) 180”C15 hours V & after sono
Twenty test packages were prepared by performing clarification. Next, this package was heated to 85℃/85%RH.
After heating for 172 hours, VPS (paper phase soldering) was performed at 215° C. for 90 seconds. Thereafter, a PCT test was conducted to check for disconnection defects in the aluminum wiring. In addition, in order to investigate the mold staining property of each molding material, we continuously molded a 100mφ x 3mat disc (50 times).
The degree of contamination on the surface of the mold was visually observed.

Table 11 shows the results of moisture resistance and mold stain resistance.

From the results in Table wi1, the example products are excellent in both moisture resistance and mold stain resistance. On the other hand, Comparative Examples 1, 2, and 3 have good mold stain resistance, but Comparative Example 1 does not contain solid silicone, and Comparative Example 2 does not contain ureido silane.
has poor moisture resistance. Furthermore, Comparative Example 3, which does not contain both solid silicone and ureido silane, has even worse moisture resistance.

〔Effect of the invention〕

If semiconductor parts are encapsulated using the molding material of the present invention, there will be no mold contamination, so molding workability will be good, and mm
A highly reliable product with improved performance can be obtained.

Claims (1)

[Claims] 1. (A) An epoxy resin having two or more epoxy groups in one molecule (B) A compound having two or more phenolic hydroxyl groups in one molecule (C) Component (A) above or (B) a reaction product of component and reactive silicone oil (D) a solid silicone polymer with a maximum particle size of 150 μm or less and a hardness of 80 or less (E) a ureido group-containing silane coupling agent (F) an inorganic filler as an essential component An epoxy resin molding material for semiconductor encapsulation, which is characterized by being formed as: 2. The epoxy resin molding material for semiconductor encapsulation according to claim 1, wherein the component (A) is a novolac type epoxy resin having an epoxy equivalent of 220 or less. 3. The epoxy resin molding material for semiconductor encapsulation according to claim 1, wherein the component (B) is a novolac type phenolic resin having a number average molecular weight of 300 to 600.