JP3410894B2 - Epoxy resin composition for semiconductor encapsulation - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is to obtain an epoxy resin composition for a semiconductor encapsulating resin having good moldability. [0002] Epoxy resin-based resin compositions for semiconductor encapsulation have been developed and manufactured to protect the IC body from mechanical and chemical actions. Items required for this vary depending on the structure of the IC package to be sealed. Here 1
In 0 years, the surface mounting of IC packages has progressed, and a sealing resin composition having high solder crack resistance has been required.
In order to improve the solder crack resistance, the resin composition must be made low in water absorption. In order to reduce water absorption, it is necessary to increase the content of the inorganic filler, and for that purpose, a low-viscosity epoxy resin and a curing agent are required. However, since a low-viscosity epoxy resin or a curing agent has a slow curing reaction, a resin composition using the same generally has poor releasability. In other words, there has been a serious problem in that the molded product is not peeled off from the mold, or a part of the molded product remains in the mold at the time of mold release. It has been desired to develop a release agent that can satisfactorily release a resin composition having poor curability. DISCLOSURE OF THE INVENTION [0003] The present invention is directed to a resin composition which improves the releasability of an epoxy resin composition for semiconductor encapsulation, and which can satisfactorily mold / release a resin composition having poor curability. Is to provide. [0004] The present inventor has made intensive studies to achieve the above object. As a result, it was found that the resin composition having the following composition was excellent in moldability and had no problem in reliability. That is, the present invention provides an epoxy resin, a phenol resin curing agent, a curing accelerator, an inorganic filler and a softening point of 1
20 ° C. or higher, crystallinity 80% or higher, average particle size 200 μm
m the following fine high density polyethylene as an essential component, the upper
The amount of the finely divided high-density polyethylene is the total sealing resin composition
An epoxy resin composition for encapsulating a semiconductor, wherein the content is 0.02 to 1.00% by weight in the product. [0005] Each composition will be described below. The epoxy resin used in the present invention refers to a compound having an epoxy group in a molecule. For example, orthocresol novolak type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, triphenolmethane type epoxy resin, naphthalene type epoxy resin, biphenyl type epoxy resin and the like can be mentioned. Also,
The degree of polymerization and epoxy equivalent of these resins are not particularly limited. However, in the case of a resin composition for surface mounting,
It is necessary to increase the amount of the inorganic filler, and an epoxy resin having a viscosity as low as possible upon melting is desired. In order to improve the moisture resistance reliability, it is desirable that chlorine ions, sodium ions and other free ions contained in these epoxy resins are as small as possible. The phenolic resin curing agent used in the present invention refers to a compound containing a phenolic hydroxyl group in the molecule. For example, a phenol novolak resin, a paraxylylene-modified phenol resin, a triphenolmethane-type phenol resin, bisphenol A and the like can be mentioned. There is no problem even if these curing agents are modified with silicone. Further, the hydroxyl equivalent, the degree of polymerization, and the like are not particularly limited. As with the epoxy resin, a curing agent having a relatively low viscosity tends to be desirable for the sealing resin composition for surface mounting.
In order to improve the moisture resistance reliability of these resins, it is desirable that chlorine ions, sodium ions and other free ions contained as impurities be as small as possible. The curing accelerator used in the present invention may be any one which promotes a chemical reaction between an epoxy group and a phenolic hydroxyl group. For example, 1,8-diazabicyclo (5,
4,0) undecene-7 (DBU), 2-methylimidazole, triphenylphosphine, tetraphenylphosphine / tetraphenylborate and the like. In the case of a formulation containing a low-viscosity epoxy resin and a curing agent, if the reactivity of the curing accelerator is not high, the hardness after molding is low and mold release failure occurs, so the curing reaction can proceed sufficiently under molding conditions. It is more desirable to select the kind and amount of the curing accelerator that can be obtained. The inorganic filler used in the present invention includes:
Fused silica powder, spherical silica powder, crystalline silica powder, 2
Sub-agglomerated silica powder, alumina and the like are mentioned, and spherical silica powder is particularly preferable from the viewpoint of improving the fluidity of the resin composition. Regarding the shape of the spherical silica powder, in order to improve the fluidity, it is desirable that the shape of the particles themselves be infinitely spherical and that the particle size distribution be broad.
The inorganic filler may be previously surface-treated with a silane-based, titanium-based, or other surface treatment agent. The amount of the inorganic filler is not particularly limited. The average particle size and the maximum particle size are not particularly limited. The high-density polyethylene used in the present invention is an important technical point in the present invention, and will be described in detail. Because polyethylene has low surface energy, it easily bleeds out on the surface of molded products during molding even when kneaded into various compounds (not limited to resin compositions for semiconductor encapsulation). It has been used as an agent. By using the high-density polyethylene of the present invention, the following characteristics of the epoxy resin composition are improved. Since the surface energy of high-density polyethylene is low, good releasability can be exhibited with a small amount of addition.
Since this high-density polyethylene has a high softening point and a high viscosity at the time of molding, there is little mold contamination during continuous molding. Further, it has excellent long-term thermal stability and reduces the number of cleaning times of the mold. Since the surface energy of the high-density polyethylene is low, it adheres well to various metals and various plastics of the lead frame, and the adhesive strength is improved and the moisture resistance is also improved. Hereinafter, the features and usage will be described in detail. The softening point of the high-density polyethylene used in the present invention is 120 ° C. or higher. The resin composition for semiconductor encapsulation is usually kneaded at about 100 ° C.
It was thought that uniform dispersion during kneading was not possible if the temperature was 0 ° C. or higher, but experiments have shown that kneading can be performed without any problem. Although the reason is not clear, it is presumed that, due to the high shearing force at the time of kneading, the epoxy resin and the curing agent are mixed due to the solvent effect and are uniformly dispersed. From the results of several experiments, it was found that high-density polyethylene having the above softening point was effective for improving the releasability. The softening point of the high-density polyethylene in the present invention is desirably 120 ° C. or higher. High-density polyethylene having a softening point of less than 120 ° C. tends to cause mold contamination in continuous molding. The method for measuring the softening point in the present invention is the ring and ball method, and has an inner diameter of 15.9 mm and a depth of 6.4.
The test piece was melted and poured into a brass ring of mm or a molded or punched one was fitted. A steel ball with a diameter of 9.53 mm and a weight of 3.5 g was placed on the center of the test piece, and this was put into an oil bath. The liquid temperature is raised at 5 ° C./min. As the temperature rises, the steel ball falls. The softening point is the temperature of the oil bath when the steel ball comes into contact with the plate 25.4 mm below the lower end of the brass ring. The high-density polyethylene used in the present invention is a high-density polyethylene having a crystallinity of 80% or more. When the degree of crystallinity is less than 80%, the crystallinity is low, so that it is liable to cause oxidative deterioration due to heat. In continuous molding at high temperature and for a long time, the oxidized polyethylene is stuck to the surface of the molding die thickly, and the die becomes thick. The main cause of dirt. The crystallinity is measured by a density method, in which a piece of polyethylene is placed in a test tube in a water bath at 25 ° C., and a mixture of water and ethanol is charged. Change the mixing ratio of water / ethanol so that the polyethylene fragments float. The specific gravity of the water / ethanol solution in this state is measured with a pycnometer, and the specific gravity of polyethylene is calculated. Since the specific gravity of both amorphous and crystalline polyethylene is known, the degree of crystallinity is calculated from the data based on the following equation. Crystallinity (%) = ρ _c (ρ−ρ ₂ ) / ρ (ρ _c −ρ ₂ ) × 1
Where ρ: specific gravity of polyethylene ρ _c : specific gravity of polyethylene crystal ρ ₂ : specific gravity of polyethylene amorphous Further, it is necessary that the average particle size is reduced to 200 μm or less. Since the softening point is equal to or higher than the kneading temperature of 100 ° C., kneading is basically difficult. For this purpose, it is necessary that the powder be pulverized before kneading. From the experimental results, it was found that the average particle size was desirably 200 μm or less. If the average particle size exceeds 200 μm, the polyethylene will not be uniformly dispersed, causing mold staining. The method of measuring the average particle size in the present invention was analyzed using a laser particle size analyzer manufactured by Horiba, Ltd. The dispersion medium is a mixture of water / ethanol. The molecular weight and molecular weight distribution of the high-density polyethylene used in the present invention, and the primary structure of the polymer, such as branched or linear, are not particularly limited. Softening point, crystallinity and average particle size are the most important parameters. The compounding amount of the high-density polyethylene in the present invention is 0.02 to
1.00% by weight is desirable. If it is less than 0.02% by weight, it does not function sufficiently as a mold release agent, resulting in mold release failure.
If the content exceeds 1.00% by weight, the high-density polyethylene bleeds out, causing problems such as mold stains, burrs, and poor adhesion to the lead frame. The high-density polyethylene of the present invention can be used in combination with other types of release agents, or used alone. However, when used together, the release agent is 2/2 of all release agents.
Less than 0% by weight is desirable. If the amount exceeds 20% by weight, any of mold stains, mold releasability, and adhesion to various substrates deteriorates, and the balance of characteristics as a resin composition is lost. The release agent used in combination is preferably an ester wax such as carnauba wax or an acid wax such as stearic acid wax or lead stearate, but is not particularly limited. The resin composition of the present invention may contain, if necessary, a coloring agent such as carbon black, a brominated epoxy resin, a flame retardant such as antimony trioxide, a silane coupling agent, a silicone oil, a rubber, and the like, if necessary. Stress components can be added. The resin composition of the present invention is prepared by mixing an epoxy resin, a phenolic resin curing agent, a curing accelerator, an inorganic filler, and other additives at room temperature with a mixer, kneading with a general kneading machine such as a roll, an extruder, and cooling. It can be pulverized to obtain a molding material. The present invention will be specifically described below with reference to examples.
Example 1 The following composition Biphenyl type epoxy resin (epoxy equivalent: 195) 5.8 parts by weight Phenol aralkyl type resin (hydroxyl equivalent: 175) 5.7 parts by weight Spherical silica powder 85.0 parts by weight High density polyethylene A 0.5 parts by weight 1.8-diazabicyclo (5,4,0) undecene-7 0.2 parts by weight Carbon black (average particle diameter 18 nm) 0.3 parts by weight Brominated phenol novolak type epoxy resin 1.0 part by weight 1.3 parts by weight of antimony trioxide 0.5 part by weight of an epoxysilane coupling agent was mixed at room temperature with a mixer, kneaded at 100 ° C. with a biaxial roll, cooled and pulverized to obtain a molding material. The obtained molding material was evaluated by the following evaluation method. << Evaluation Method >> Softening point: Ring and ball method Crystallinity: Density method molding Evaluation: 160 pQ of low pressure transfer molding mold
An FP molding test was performed. The releasability of a molded product molded at a molding temperature of 175 ° C. and a curing time of 2 minutes is organoleptically evaluated in three stages of ○, Δ and ×. Further, the state of the surface of the obtained molded article was visually observed, and the presence or absence of mold contamination was determined in three stages of ○, Δ, and ×. Solder resistance evaluation: 80 pQFP (1.
(5 mm thickness) was obtained, and post-cured at 175 ° C. for 8 hours to obtain a sample. Six packages were obtained for each part number. After being charged in an 85 ° C., 85% constant temperature / humidity chamber for 168 hours, an IR reflow treatment at 240 ° C. was performed. The peeling inside the package after the treatment was observed with an ultrasonic flaw detector, and the solder resistance (and adhesion) was determined based on the number of packages having the chip surface peeling and the pad back surface peeling. << Examples 2 to 6 >> Of the formulations of Example 1, only the type of high-density polyethylene was changed as shown in Table 1 as the release agent (other formulations were the same as in Example 1). Then, a molding material was obtained in the same manner as in Example 1 and evaluated in the same manner. However, in Example 6, carnauba wax was used in combination. << Comparative Examples 1 to 6 >> Among the formulations of Example 1, a formulation in which the kind of high-density polyethylene as a mold release agent or the blending amount of the mold release agent and spherical silica was changed as shown in Table 2 (other formulations were the same as in Example 1) In the same manner as in Example 1 to obtain a molding material, which was evaluated in the same manner. * Characteristics of high density polyethylene used Softening point Crystallinity Average particle size (° C) (%) (μm) High density polyethylene A 142 96 105 High density polyethylene B 125 95 105 High density polyethylene C 140 85 105 High Density polyethylene D 143 97 195 High density polyethylene E 162 98 53 High density polyethylene F 111 81 103 High density polyethylene G 124 79 102 High density polyethylene H 142 96 266 Table 1 Example 1 2 3 4 5 6 blending (parts by weight) Diphenyl ethoxy resin 5.8 5.8 5.8 5.8 5.8 5.8 Phenol aralkyl type resin 5.7 5.7 5.7 5.7 5.7 5.7 5.7 Spherical silica 85.0 85.0 85.0 85.0 85.0 85.0 High density polyethylene A 0.5 0.2 High-density polyethylene B 0.5 High-density polyethylene C 0.5 High-density polyethylene D 0.5 High-density polyethylene E 0.5 Carnauba wax 0.3 Characteristics Releasability ○ ○ ○ ○ ○ ○ Mold stainability ○ ○ ○ ○ ○ ○ Solder resistance evaluation: chip peeling 0 0 0 000 0 Soldering resistance evaluation: Pad peeling 0 0 0 0 0 0 ─────── Comparative example 1 2 3 4 5 6 ──────────────────────────────────配合 Formulation (parts by weight) Diphenyl ethoxy resin 5.8 5.8 5.8 5.8 5.8 5.8 5.8 Phenol aralkyl type resin 5.7 5.7 5.7 5.7 5.7 5.7 5.7 Spherical silica 85.0 85.49 84.3 85.0 85.0 85.0 High density polyethylene A 0.01 1.2 High density polyethylene F 0.5 High density polyethylene G 0.5 High density polyethylene H 0.5 Carnauba wax 0.5 ──────── ──────────────────────────── Characteristics Releasability △ × ○ ○ ○ ○ Mold contamination △ ○ × × × × Solder resistance evaluation : Chip peeling 102 1 2 1 Solder resistance evaluation: Pad peeling 2 0 3 1 1 1 0 According to the present invention, it is possible to obtain a highly reliable epoxy resin composition for semiconductor encapsulation with good releasability. And reduce production costs at semiconductor manufacturers. That.

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Claims (1)

(57) [Claims] [Claim 1] Epoxy resin, phenol resin curing agent,
Curing accelerator, an inorganic filler and a softening point of 120 ° C. or higher, crystallization of 80% or more, an average particle size 200μm or less finer high-density polyethylene as an essential component, the fine dense potentiation
The amount of ethylene in the total sealing resin composition is 0.02 to
An epoxy resin composition for semiconductor encapsulation, which is 1.00% by weight .