JP2001342326A - Method of manufacturing epoxy resin composition for photosemiconductor sealing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing an epoxy resin composition for an photosemiconductor sealing excellent in transparency and solder resistance. SOLUTION: In a method of manufacturing an epoxy resin composition for an photosemiconductor sealing which contains as essential components, an epoxy resin, a curing agent, a cure promoter, and an inorganic filler, the inorganic filler and at least a part of the resin composition are melt mixed, or the inorganic filler and at least a part of the melt of the resin composition are mixed, and the mixture is treated with a wet bead mill, then pulverized, and the pulverized material and the rest of the components are preliminarily mixed, and then it is heated and kneaded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an epoxy resin composition for encapsulating an optical semiconductor having excellent transparency and solder resistance.

[0002]

2. Description of the Related Art In recent years, in order to reduce the size of communication information equipment, improve the integration density, and simplify the manufacturing process, the semiconductor industry has rapidly increased the demand for a surface mounting method instead of the conventional mounting method. Further focusing on the field of optoelectronics, transparency is a very important factor in addition to the function of the conventional semiconductor sealing resin. That is, in an opto-device such as a photosensor, an LED, and a light-emitting element, even if a mounting method such as IR reflow in surface mounting is performed, transparency is not impaired, and furthermore, package cracking due to thermal shock, There is a demand for a highly reliable sealing resin which does not cause separation between the resin and the chip or the lead frame.

[0003] As a resin for encapsulating an optical semiconductor, there is an epoxy resin composition of an acid anhydride curing agent type which is excellent in transparency and can obtain a high transmittance even in a visible light region. Is high, the water absorption of the resin composition is high, and when a surface-mount type optical semiconductor package is mounted by IR reflow or the like, package cracks due to thermal shock and peeling between the chip and the lead frame and the resin frequently occur. It is well known to those skilled in the art that adding fillers is a typical solution. This means that by filling an inorganic filler such as silica into the resin composition at a high ratio, the water absorption of the sealing resin composition, the coefficient of linear expansion can be reduced, and deformation and cracks at high temperatures can be suppressed. However, in the resin composition thus obtained, the light transmittance of the cured resin becomes extremely low due to the influence of light reflection and refraction occurring at the interface between the silica particles and the resin. It is known that the amount of light reflected and refracted at the interface between the resin and the filler when the light passes through the cured product of the resin composition is proportional to the difference in the refractive index before and after the interface. The refractive index of general silica particles is around 1.4, whereas the cured body of epoxy resin is around 1.5, and it is difficult to eliminate this point unless the type of filler is changed. .

In Japanese Patent Application Laid-Open No. 5-6946, silica-based fine particles, particularly fine particles having an average particle diameter of 0.5 μm or less, are mixed with an epoxy resin, and a filler having a particle diameter smaller than the wavelength of light is added. Is described as being transparent and having low internal stress. However, when a filler having a particle diameter smaller than the wavelength of light is added, agglomerates of the filler are generated, and there is a problem that the cured product of the resin composition becomes cloudy. As a method of eliminating aggregation, a method of applying a sol-gel method using an alkoxysilane or the like as a raw material of a filler is described in this publication. However, this sol-gel method requires a very large number of steps and is costly. Further, the polymerization synthesis by the sol-gel method requires a solvent, a step of removing the solvent is indispensable, and the remaining solvent affects the device when the optical semiconductor is sealed.

Japanese Patent Application Laid-Open No. 5-287082 describes a technique in which ultrafine particles are dispersed in an organic solvent in advance, a solution in which the ultrafine particles are dispersed is mixed with a resin component, and the ultrafine particles are dispersed in the resin component. . According to this technique, ultrafine particles are uniformly dispersed without secondary aggregation, and excellent light transmittance is obtained. However, as a result of investigations by the present inventors, the organic solvent used for dispersing the ultrafine particles remains in the resin composition, and when the optical semiconductor element is sealed, the organic solvent remaining in the composition is removed. Was volatilized at the time of molding and bubbles were generated in the package.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing an epoxy resin composition for encapsulating an optical semiconductor having excellent transparency and solder resistance.

[0007]

Means for Solving the Problems The present inventors have found that a resin composition having excellent transparency and solder resistance can be obtained by uniformly dispersing an inorganic filler by a specific method. The invention has been completed.

That is, the present invention provides a curing agent, a curing accelerator and an inorganic filler selected from the group consisting of an epoxy resin having two or more epoxy groups in one molecule, an acid anhydride curing agent and a phenol curing agent. In the method for producing an epoxy resin composition for optical semiconductor encapsulation as an essential component, the inorganic filler and at least a part of the resin component are melt-mixed, or at least a part of the melt of the resin component and the inorganic An epoxy resin composition for encapsulating an optical semiconductor, comprising: mixing a filler; treating the mixture with a wet bead mill; and pulverizing the mixture; preliminarily mixing the pulverized product with the remaining components; and kneading with heat. It is a method of manufacturing a product.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The epoxy resin having two or more epoxy groups in one molecule used in the present invention is not limited as long as it has two or more epoxy groups in one molecule. However, it is more preferable to use a less colored epoxy resin from the viewpoint of transparency, and specific examples thereof include bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin,
Polyfunctional heterocyclic epoxy resins such as biphenyl type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, alkyl-modified triphenol methane type epoxy resin, hydrogenated bisphenol A type epoxy resin, triglycidyl isocyanurate, Examples thereof include polyfunctional alicyclic epoxy resins such as poly (epoxidized cyclohexene oxide). These may be used alone or in combination of two or more.

[0010] Among the curing agents selected from the group consisting of an acid anhydride curing agent and a phenol curing agent used in the present invention, the acid anhydride curing agents include phthalic anhydride, maleic anhydride, trimellitic anhydride, and anhydride. Pyromellitic acid, hexahydrophthalic anhydride, 3-methyl-hexahydrophthalic anhydride, 4-methyl-hexahydrophthalic anhydride, or a mixture of 3-methyl-hexahydrophthalic anhydride and 4-methyl-hexahydrophthalic anhydride, tetrahydro Examples include phthalic anhydride, nadic anhydride, methylnadic anhydride, and the like, but are not particularly limited thereto, and may be used alone or in combination of two or more.
The phenol curing agent is not particularly limited as long as it is a commonly used phenol curing agent. Phenol novolak resin, cresol novolak resin, phenol aralkyl resin, terpene-modified phenol resin, bisphenol A
Mold novolak resin and the like are exemplified. In the present invention, the acid anhydride curing agent and the phenol curing agent may be used alone or in combination.

As the curing accelerator used in the present invention, those usually used for anionic curing of an epoxy resin include:
Although all can be used, examples thereof include imidazoles, tertiary amines, quaternary ammonium salts, bicyclic amidines such as diazabicycloundecene and derivatives thereof, phosphine, phosphonium salts and the like. However, there is no particular limitation as long as it has good curability and no coloring, and it may be used alone or in combination of two or more.

The inorganic filler used in the present invention is preferably an inorganic filler having a maximum particle size smaller than the wavelength of light from the viewpoint of transparency. For example, when used in a product that transmits ultraviolet light. It is preferable that the maximum particle size is 0.3 μm or less. Here, the particle size of the inorganic filler may be measured by a known method, but the volume particle size distribution of the particles is measured by a laser light scattering method, and the value of the true density of the particles is used to calculate the weight particle size distribution. It is preferable to use a conversion method.

Examples of the composition of the inorganic filler include fused silica powder, crystalline silica powder, alumina, silicon nitride, and glass. From the viewpoint of transparency, it is more preferable to use glass whose refractive index can be controlled. These may be used alone or as a mixture. Further, as the inorganic filler, a material which has been surface-treated with a silane coupling agent or the like in advance may be used.

In the present invention, in addition to the above-mentioned components, if necessary, other additives known to those skilled in the art, such as an epoxy resin, an antioxidant, a releasing agent, a coupling agent, and a filler, and auxiliary materials may be combined. I can't do anything.

In the present invention, the above-mentioned components are appropriately blended. For example, the equivalent ratio of the epoxy resin to the curing agent, that is, the epoxy group of the epoxy resin and the acid anhydride group of the acid anhydride curing agent or the phenol curing agent is used. Of the phenolic hydroxyl group of 0.8 to 1.4, more preferably 1.0 to 1.4.
1.2, and the total weight of the epoxy resin and the curing agent is 10
When it is set to 0, the addition amount of the curing accelerator is preferably 0.5 to 2 parts by weight. The inorganic filler is blended so as not to affect the characteristics of the optical semiconductor application.

According to the production method of the present invention, first, an inorganic filler and a part or all of a resin component are melted and mixed by heating or
Alternatively, a melt obtained by previously heating and melting part or all of the resin component is mixed with an inorganic filler, and then the molten mixture is treated using a wet bead mill. Next, after separating and removing the beads, the treated product is pulverized using a ceramic roll pulverizer or the like, and the pulverized product is preliminarily mixed with the remaining components, and then heated and kneaded to obtain an epoxy resin composition. Obtainable.

The wet bead mill used in the present invention is not particularly limited as long as it has a rotor for creating a shear field and beads moving in the shear field in a container for processing a resin containing an inorganic filler. Equipped with a heating mechanism in the container and the piping section attached to it, a pump mechanism that can repeatedly process the resin containing the inorganic filler, and a separator mechanism that prevents beads from flowing out when discharging the resin. It is preferable to use the continuous type provided. The beads to be used are not limited. Depending on the material and the fraction of the inorganic filler, for example, zirconia, alumina, iron, or the like having a diameter of about 0.2 to 1.0 mm can be used. It is preferable to fill 20 to 90% by volume of the effective volume.
In the case of a continuous wet bead mill equipped with a separator mechanism, the viscosity of the resin containing the inorganic filler is adjusted by adjusting the processing temperature, the amount of the inorganic filler, and the processing flow rate in order to smoothly perform the repetitive processing. Up to 100
It is necessary to set it to Pa · s or less. The melt mixer used before the bead treatment is not particularly limited, but a pressure kneader, a twin screw extruder, a Henschel mixer equipped with a heating mechanism, or the like can be used.

The premixer used for premixing after bead milling in the present invention is not particularly limited, but a Henschel mixer having a plurality of blades attached to a rotating shaft, a scraper attached to a central shaft, and a side mixer. In addition to a tolero mixer with a disperser attached, a planetary mixer that rotates around the planet while the central axis rotates, a kneader that rotates two wave-shaped axes, a colloid mill, a pot type or continuous ball mill, , A roll mill and a closed multi-stage shearing extruder can be used. Further, it is preferable to provide a cooling mechanism so that premixing can be performed in a temperature range where the resin component does not melt or soften.

The heating kneader used after the premixing in the present invention is not particularly limited, but a single-screw extruder including a co-kneader, a twin-screw extruder, a heating roll, a continuous kneader, a Banbury mixer and the like can be used.

In the present invention, by treating with a wet bead mill, the inorganic filler having a particle size smaller than the wavelength of light is uniformly dispersed in a part or all of the melt of the resin component, and has high transparency. An epoxy resin composition for encapsulating an optical semiconductor can be obtained.

The optical semiconductor encapsulating epoxy resin composition thus obtained can be encapsulated by a general method. For example, the optical semiconductor element is encapsulated by a transfer molding method or the like. Thus, an optical semiconductor device sealed with a cured product of the epoxy resin composition can be obtained.

[0022]

EXAMPLES Examples are shown below, but the invention is not limited thereto.

Example 1 70.20 parts by weight of bisphenol A type epoxy resin (Epicoat 1001, made by Yuka Shell Epoxy, epoxy equivalent: 475), a mixture of hexahydrophthalic anhydride and methylhexahydrophthalic anhydride (acid anhydride) Product hardener, Shin-Nippon Rika MH-700) 20.
97 parts by weight, 0.91 part by weight of 2-methylimidazole (curing accelerator, 2MZ manufactured by Shikoku Chemicals), 1.8 parts of triphenylphosphite (antioxidant A, TPP-R manufactured by Sumitomo Chemical)
1 part by weight, 0.46 parts by weight of hindered phenol (antioxidant B, BHT-P manufactured by Honshu Chemical), 0.65 parts by weight of montanic acid (release agent, Hoechst S manufactured by Clariant Japan), inorganic filler [average Alumina having a particle size of 13 nm] 5.
The formulation composed of 00 parts by weight was designated as Basic Formulation A.

From the basic compound A, a mixture obtained by melting and mixing an epoxy resin and an inorganic filler with a pressure kneader (120 ° C., 15 minutes) is used. Zirconia beads having a diameter of 0.8 mm are placed in a processing container (2 liters in volume). Wet bead mill device filled with 20% by volume (rotor rotation speed 3000 rpm, temperature 120
° C, flow rate 15 l / min, separator interval 0.2 m
m) for 30 minutes, and then cooled and pulverized, and this was mixed with an acid anhydride curing agent and an antioxidant A among the remaining components of the basic compound A, and then reacted at 120 ° C. for 3 hours. After cooling and pulverizing, the mixture was preliminarily mixed with the remaining components of the basic compound A for 5 minutes using a Henschel mixer (capacity: 15 liters, rotation speed: 1000 rpm, cooling at 10 ° C.). Kneader (roll diameter 10 inches,
The mixture was kneaded at a heating temperature of 70 ° C.) for 20 minutes. Thereafter, the mixture was cooled and pulverized to obtain an epoxy resin composition. This resin composition was heated at a mold temperature of 1 using a low-pressure transfer molding machine.
75 ° C., injection pressure 6.86 × 10 ⁶ Pa, curing time 2
The test pieces used in each test were prepared under the conditions of 150 ° C. for 2 hours and post-curing for 2 minutes. The evaluation method is as follows.
The results are summarized in Table 1.

(Example 2) Of the basic compound A used in Example 1, an inorganic filler was changed to glass having an average particle diameter of 100 nm (composition ratio: SiO ₂ / Al ₂ O ₃ / CaO = 56/22 /
20, the remaining components are silicone-based defoamers and are prepared so as to have the same refractive index as the cured product of the resin component of the basic compound A).
A resin composition was obtained by the production method. Table 1 shows the evaluation results.
Are shown together.

Comparative Example 1 An epoxy resin composition was obtained in the same manner as in Example 1 except that the wet bead mill treatment was omitted.
That is, of the basic compound A, the epoxy resin, the acid anhydride curing agent, and the antioxidant A are reacted in a reaction vessel at 120 ° C. for 3 hours, then cooled, pulverized, and then together with the remaining components. The mixture preliminarily mixed for 5 minutes with a Henschel mixer (capacity: 15 liters, rotation speed: 1000 rpm, cooling at 10 ° C.) was kneaded for 20 minutes by a heated two-roll kneader (roll diameter: 10 inches, heating temperature: 70 ° C.). Then cool down,
This was crushed to obtain an epoxy resin composition. The evaluation results are shown in Table 1.

(Comparative Example 2) Of the basic compound A, an alumina inorganic filler having an average particle diameter of 13 nm was mixed with methyl ethyl ketone so as to be 20% by weight, and stirred at room temperature for 2 hours to prepare an alumina dispersion solution. . Next, the epoxy resin in the basic formulation A was added, and the mixture was dissolved and stirred at room temperature for 3 hours. Thereafter, the pressure was reduced to remove methyl ethyl ketone, and an epoxy resin in which alumina was dispersed was obtained. The acid anhydride curing agent and the antioxidant A of the basic compound A are added to this epoxy resin, and the mixture is reacted at 120 ° C. for 3 hours in a reaction vessel, cooled and pulverized, and then the remaining components of the basic compound A are added. Was premixed with a Henschel mixer for 5 minutes, and kneaded with a heated two-roll kneader for 20 minutes. Thereafter, the mixture was cooled and pulverized to obtain an epoxy resin composition. Table 1 shows the evaluation results.
Are shown together.

(Measurement of Light Transmittance) A test piece of 10 × 30 × 1 mm was prepared from the resin composition obtained above and a spectrophotometer (a self-recording spectrophotometer UV-3 manufactured by Shimadzu Corporation) was used.
100), the light transmittance at 400 nm with a thickness of 1 mm was measured.

(Evaluation of Appearance) Using the resin composition obtained above, a surface mounting package (12 pins, 4 × 5 m
m, thickness 1.2 mm, chip size 1.5 mm × 2.
0 mm, 42 alloy lead frame), mold temperature 175 ° C, injection pressure 6.86 × 10 ⁶ Pa, curing time 2
Transfer molding at 150 ° C for 2 hours.
Post cured. The resulting optical semiconductor package was visually inspected for bubbles.

(Evaluation of Solder Resistance) The optical semiconductor package obtained in the same manner as above was left in an environment of 85 ° C. and a relative humidity of 60% for 168 hours, and then subjected to IR reflow treatment at 240 ° C. The processed package was examined with a microscope and an ultrasonic flaw detector to check for cracks and separation between the chip and the resin.

[0031]

[Table 1]

As is clear from the results shown in Table 1, the resin composition obtained by the production method of the present invention has excellent transparency and good solder resistance.

[0033]

The epoxy resin composition for encapsulating an optical semiconductor obtained by the production method of the present invention is excellent in transparency and solder resistance, and can provide an optical device having high reliability. .

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08K 3/00 C08K 3/00 5F088 H01L 23/29 H01L 33/00 N 23/31 23/30 R 31 / 02F 33/00 31/02 B (72) Inventor Hitto Akiyama 2-5-8 Higashishinagawa, Shinagawa-ku, Tokyo Sumitomo Bakelite Co., Ltd. F term (reference) 4F070 AA44 AA46 AC11 AC15 AC22 AC23 AC28 AC40 AC46 AC55 AC86 AE01 AE08 DA41 DA43 DA45 DA50 DB10 DC05 FA03 FB04 FB07 4J002 CC032 CC072 CD001 CD021 CD041 CD051 CD061 CD141 CE002 DE148 DJ008 DJ018 DL008 EL136 EL146 EN007 EN137 EU097 EU117 EW017 EW177 FD018 FD142 AFD01 AD01 AF01 AF01 AF01 AD07 AF01 DA04 DC02 DC41 DD07 FA01 FA03 FA05 FB07 JA07 4M109 AA01 CA21 EA02 EB02 EB03 EB04 EB12 EC05 EC11 GA01 5F041 AA34 AA44 DA44 5F088 JA06 J A20

Claims (1)

[Claims] An essential component is an epoxy resin having two or more epoxy groups in one molecule, a curing agent selected from the group consisting of an acid anhydride curing agent and a phenol curing agent, a curing accelerator, and an inorganic filler. In the method for producing an epoxy resin composition for encapsulating an optical semiconductor, the inorganic filler and at least a part of the resin component are melt-mixed, or at least a part of the melt of the resin component and the inorganic filler. Mixing the mixture, treating the mixture with a wet bead mill and then pulverizing the mixture, preliminarily mixing the pulverized product with the remaining components, and kneading the mixture by heating and kneading the mixture. .