JPH01190748A - Epoxy resin composition for semiconductor encapsulation - Google Patents

Abstract

PURPOSE:To obtain an epoxy resin composition for semiconductor sealing, having a high thermal conductivity and good moldability and humidity resistance, by using a specified highly pure fine alpha-alumina particles as a filler. CONSTITUTION:An epoxy resin composition having excellent moldability and humidity resistance as well as a very high thermal conductivity and most suited for sealing a semiconductor device can be obtained by using a filler comprising alpha-alumina having a purity >=99.5%, an Na2O content <=0.03%, an Na ion content <=5ppm when extracted with water at 100 deg.C and a Cl ion content <=1ppm, a mean particle diameter of 5-60mum and a content of particles of a particle diameter >=250mum >=1%.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an epoxy resin composition for semiconductor encapsulation that has high thermal conductivity and good moldability and moisture resistance.

Inorganic fillers such as fused silica and crystalline silica are mainly used as materials, and crystalline silica, which has good thermal conductivity, is used especially for applications that require high thermal conductivity.

However, even if crystalline silica is used as a filler and its amount is increased, the thermal conductivity of the composition remains at 65c.
Al/■・sec・℃ is the limit, and if the content of crystalline silica is increased to further increase the thermal conductivity, the fluidity of the composition will become extremely poor, making transfer molding difficult. The disadvantage is that it is impossible.

Therefore, in order to further increase the thermal conductivity of the epoxy resin composition, fillers such as alumina, silicon nitride, aluminum nitride, boron nitride (BN), silicon carbide, and calcium carbonate, which have higher thermal conductivity than crystalline silica, are used as fillers. One possible method is to use However, although compositions using these inorganic fillers have higher thermal conductivity than crystalline silica-containing compositions, they have the problem of lower fluidity and moisture resistance. It has been difficult to obtain an epoxy resin composition that has both these properties.

The present invention was made in view of the above circumstances, and an object of the present invention is to provide an epoxy resin composition that has high thermal conductivity, moldability, and moisture resistance.

Means and Effects for Solving the Problem In order to achieve the above object, the present inventors conducted extensive studies on fillers used in epoxy resin compositions for semiconductor encapsulation, and found that the purity (AQ203 amount) was 99. 5% or less and the content of impurity Na2O is 0.05% or less,
The Na ion content is 5 ppm or less, the Cl ion content is 1 ppm or less, and the average particle size is 5 Iln to 6
When α-alumina with a particle size of 0/a and 1% or less of particles with a particle size of 250p or more is used, a high thermal conductivity of about twice or more than a composition using crystalline silica at the same blending amount can be obtained. The present inventors have discovered that an epoxy resin composition can be obtained which has good fluidity and moisture resistance, and has high thermal conductivity, moldability, and moisture resistance, thereby achieving the above object. This is what we have come to do.

Therefore, the present invention has a purity of 99.5% or more, a Na2O content of 0.03% or less, a Na ion content of 5 ppm or less, and a Cl ion content of 5 ppm or less when extracted with water at 100°C. 1 ppm or less, an average particle diameter of 511n to 60n, and a content of particles with a particle diameter of 250n or more of 1% or less is used as a filler. An epoxy resin composition for sealing is provided.

The present invention will be explained in more detail below.

The epoxy resin composition for semiconductor encapsulation of the present invention is composed of an epoxy resin, a curing agent, a filler, and, if necessary, a curing accelerator, a mold release agent, a pigment, a silane coupling agent, and the like.

In this case, the epoxy resin used in the composition of the present invention is not particularly limited as long as it has one or more epoxy groups in one molecule, such as bisphenol type epoxy resin, alicyclic epoxy resin, cresol novolak type epoxy resin, etc. Although resins and the like are preferably used, it is particularly desirable to use a cresol novolak type epoxy resin. In addition, from the viewpoint of moisture resistance of the composition, the above-mentioned epoxy resin preferably has a hydrolyzable chlorine content of 500 ppm or less, free Na and Cl ions of 2 ppm or less, and an organic acid content of 10 ppm or less. preferable.

In addition, the hardening agent used is appropriate for the epoxy resin.
For example, acid anhydrides such as trimellitic anhydride and tetrahydrophthalic anhydride, phenol novolak resins, and the like are used, and among them, it is optimal to use phenol novolac resins. The phenol novolak resin used as a curing agent contains free Na' and Cl ions of 2 ppm or less each, and the amount of phenol in the monomer is 1% or less. Organic acids such as formic acid are 100%
It is preferable that the content of free Na, Cl ions and organic acids is higher than the above value, the moisture resistance of the semiconductor device sealed with the composition may deteriorate. If the amount is more than 1%, defects such as voids, unfilled areas, whiskers, etc. may occur in molded products made from the composition. Furthermore, the softening point of phenolic novolak resin is 5.
A temperature of 0 to 120°C is preferred; if it is less than 50°C, the glass transition point of the composition may become low and heat resistance may deteriorate; if it exceeds 120°C, the melt viscosity of the composition increases and workability is impaired. There may be cases where it is inferior to

Here, the blending amount of the curing agent is not particularly limited, but the molar ratio of the epoxy group of the epoxy resin to the phenolic hydroxyl group or acid anhydride group of the curing agent is 0.8 to 2, particularly 1 to 2.
A range of 1.5 is preferable. If the molar ratio of both groups is less than 0.8, the curing properties of the composition and the glass transition temperature (Tg) of the molded product may deteriorate, resulting in a decrease in heat resistance, while if it exceeds 1.5, the glass of the molded product may deteriorate. The transition temperature and electrical properties may deteriorate.

Furthermore, it is preferable to add a curing accelerator to the composition of the present invention in order to promote the reaction between the epoxy resin and the curing agent. As curing accelerators, compounds commonly used for curing epoxy compounds, such as imidazole compounds, 1,8
-Diazabicyclo(5゜4.0)undecene-7(D
Undecene compounds such as BU) and phosphine compounds such as triphenylphosphine are used, but from the viewpoint of moisture resistance of the composition, it is preferable to use triphenylphosphine. Note that the amount of the curing accelerator used is not particularly limited, and may be a normal amount.

The epoxy resin composition for semiconductor encapsulation of the present invention contains the above-mentioned epoxy resin curing agent as an essential component, and further contains a curing accelerator as necessary. In addition, certain α-alumina is used as a filler.

In this case, the α-alumina used as a filler in the present invention is α-crystal particles of alumina, and its aluminum oxide (A
Q203) A high purity product with a purity of 99.5% or more, preferably 99.8% or more is used.
If a composition with a purity of less than 99.5% is used, the moisture resistance of the composition will deteriorate and the object of the present invention cannot be achieved.

Such α-alumina is generally produced by using bauxite containing alumina hydrate as a raw material, crushing it, putting it in a sodium hydroxide solution, and melting it with steam heating at 150 to 250°C to form sodium aluminate. After making
It is produced by hydrolyzing the resulting aluminum hydroxide and then calcining it at 1000° C. or higher, but in this case Na2O tends to remain as an impurity in α-alumina. The α-alumina used in the present invention removes this Na2O and has a total Na2O content of 0.
0.03% or less, preferably 0.01% or less, and
Further, when 20 g of this α-alumina is extracted with 100 g of ion-exchanged water at 100°C for 2 hours, the Na ion content is 5 ppm or less, preferably 2 ppm or less, and the Cl ion content is 1 ppm or less, preferably 0. 5ppm
Use the one below. When the Na2O content and the Na ion and Cl ion contents of α-alumina are higher than the above values, the moisture resistance of the composition becomes extremely poor, and the object of the present invention cannot be achieved.

In addition, as a method for producing α-alumina used in the present invention, in addition to the above-mentioned method, for example, (a) high-purity AM pellets are placed in a reaction tank filled with pure water, an electrode is inserted into the tank, and high-frequency A method of producing aluminum hydroxide by reacting AQ pellets with water using a spark discharge, and calcining this to obtain α-alumina. Examples include a method in which α-alumina is obtained by using aluminum oxide and firing the aluminum oxide.

Furthermore, in the present invention, among the above-mentioned α-aluminas, the average particle diameter is 5 to 60 mm, preferably 10 to 50 mm.
Particles having a particle size of 250 diaphragms or more are used in an amount of 1% or less, preferably 0.5% or less of the total. If the average particle size of α-alumina is smaller than 5, the fluidity of the composition will be very poor, and the average particle size will be larger than 60 mm, or 1% of the particles will have a particle size of 250/1 m or more.
If it is present in a larger amount, the mold will be worn more severely when the composition is molded, or the gate portion of the mold will be clogged with alumina particles, causing unfilling and deteriorating moldability.

Furthermore, since α-alumina is usually manufactured by firing aluminum hydroxide, α-crystal particles gather during the process, resulting in 2
Easy to create secondary particles. These secondary particles cannot be loosened during the manufacturing process of the epoxy resin composition, and are made into a composition as is, and when a semiconductor device is made from a composition containing these secondary particles, the inside of the molded body becomes porous; In some cases, water may enter from the semiconductor device and the moisture resistance characteristics of the semiconductor device may be extremely deteriorated. Therefore, the content of secondary particles in α-alumina is preferably 10% or less, more preferably 1% or less of the total α-alumina.

In addition, the α-alumina used in the present invention has an axial ratio of the major axis to the minor axis of α particles of 1 to 2, particularly 1.2 to 1.7 when α particles are observed in a scanning electron micrograph. If α-alumina having an axial ratio of more than 2 is used, the fluidity of the composition may become extremely poor.

In this composition, the blending amount of α-alumina is not particularly limited, and the higher the blending amount of α-alumina, the higher the thermal conductivity can be obtained, but preferably 60 to 95% of the total composition. % (weight %, the same applies hereinafter), especially 75 to 90
%. If the amount of α-alumina is less than 60%, the thermal conductivity of the composition may be low, and if it is more than 95%, the composition may have poor fluidity.

In addition, in the present invention, the above-mentioned special α is used as a filler.
- Even if alumina is blended alone or together with α-alumina, crystalline silica,
An inorganic filler such as fused silica may be used in combination as necessary.

Various additives can be further added to the composition of the present invention, if necessary. Carnauba wax is preferably used from the viewpoint of moldability), organic rubber-based or silicone-based flexibility imparting agents, pigments such as carbon black, cobalt blue, red iron, flame retardants such as antimony oxide, halogen compounds, etc. One or more of surface treatment agents (γ-glycidoxypropyltrimethoxysilane, etc.), epoxysilane, vinylsilane, boromine compounds, coupling agents such as alkyl titanates, anti-aging agents, and other additives. Can be blended.

In addition, when producing the epoxy resin composition of the present invention, predetermined amounts of the above-mentioned components are uniformly stirred and mixed, and the epoxy resin composition is prepared in advance for 7 days.
It can be obtained by heating to 0 to 95°C, mixing with a kneader, roll, extruder, etc., cooling, and pulverizing. Here, there is no particular restriction on the order of blending the components.

As mentioned above, the epoxy resin composition of the present invention includes IC,
It is used for sealing semiconductor devices such as LSIs, transistors, thyristors, and diodes, and can also be effectively used for manufacturing printed circuit boards.

Here, when sealing the semiconductor device, a conventional molding method such as transfer molding, injection molding, casting method, etc. can be used. In this case, the molding temperature of the epoxy resin composition is 15
0 to 180℃, post cure at 150 to 180℃
It is preferable to carry out the treatment for 16 hours.

As explained above, the epoxy resin composition for encapsulating semiconductor devices of the present invention has extremely high thermal conductivity due to the inclusion of special α-alumina as a filler. It has excellent moisture resistance and moisture resistance, making it ideal for sealing semiconductor devices.

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited to the Examples below. In addition, in the following examples, all parts indicate parts by weight.

[Examples 1 to 4. Comparative Examples 1 to 5] 62 parts of cresol novolac epoxy resin (softening point 60°C, hydrolyzable Cl 300 ppm, Na, CD each 1 ppm, organic acid content 50 PPm, epoxy equivalent 200), brominated novolac epoxy resin (Br content 35%,
Epoxy equivalent 286) 7 parts, novolac phenol resin (softening point 80°C, free phenol amount 0.1%, organic acid 20 ppm, Na.

Cl (1 ppm each) 31 parts, 20310 parts of 5b, 2.0 parts of γ-glycytoxypropyltrimethoxysilane, 1.5 parts of carnauba wax, 2.0 parts of carbon black, 2-
0.75 parts of phenylimidazole, α-alumina [purity (AQ203 amount) 99.9%, Na2O content 0.03
%, Na ion 3PPm when extracted with water at 100°C,
Cl ion 0.5ppm, average particle size 20/j11.2
The content of particles having a particle diameter of 50/1111 or more is 0.
01%, particle axis ratio of major axis to minor axis is 1.4) 600 parts were mixed and kneaded for 8 minutes with a heated roll at 100°C, cooled, and crushed to obtain an epoxy resin molding material (Example 1). Obtained.

In addition, the average particle size of α-alumina is 25011 m.
An epoxy resin molding material having the same composition as in Example 1 above (Examples 2 to 4, Comparative Examples 1 to 5) was prepared in the same manner as above, except that the content of the above particles was the value shown in Table 1. Prepared.

The properties of the obtained epoxy resin molding material were measured by the following method.

The results are shown in Table 1.

(a) Spiral flow value: 175°C, 70°C using a mold that complies with EMMI standards.
It was measured under the condition of kg/d.

(b) Method for measuring corrosion rate of aluminum wiring 14-pin IC designed to study corrosion of aluminum metal electrodes
The epoxy resin composition was molded using a transfer molding method, and post-cured at 180°C for 4 hours. This 2
A pressure vacuum test was conducted in which the wires were left in water vapor at atmospheric pressure and 120° C., and the incidence (%) of wire breakage caused by aluminum corrosion after 500 hours was measured.

(c) Method for measuring unfilled occurrence rate Using a 500-cavity diode mold, the epoxy resin composition was molded by transfer molding for 10 shots (molding conditions: mold temperature 175°C, injection pressure 100k)
g/r&, molding time 3 minutes, preheat temperature 80°C).

The unfilled occurrence rate of 5,000 molded products was measured.

(d) Using a disc with a thermal conductivity diameter of 50+nn+ and a thickness of 6mm,
Measured using a thermal conductivity measuring machine manufactured by ).

From the results in Table 1, when the average particle diameter of α-crystal particles of α-alumina is less than 5/Irr1 (Comparative Example 1゜2), the fluidity (spiral flow value) of the composition is poor, and the composition When molding, there are many cases of unfilling, and corrosion of the AQ wiring progresses, resulting in poor moisture resistance.Also, when the average particle size of α-alumina is larger than 60 units (Comparative Example 3) or when the particle size is 250 units,
When the proportion of particles louder than voice exceeds 1% (Comparative Examples 4 and 5)
), when the composition is molded, unfilling often occurs, but in contrast, the compositions of the present invention (Examples 1 to 4) have high thermal conductivity, good fluidity, and moldability. It was confirmed that the film had excellent moisture resistance and moisture resistance.

[Example 5. Comparative Examples 6 to 10] Purity of α-alumina, Na2O content, Na ion, C
An epoxy resin composition having the same composition as in Example 1 was prepared except that the l ion content was as shown in Table 2, and its spiral flow value and AQ wiring corrosion rate were measured by the above methods.

The results are shown in Table 2.

From the results in Table 2, it can be seen that when the purity of α-alumina is worse than 99.5% (Comparative Example 6) and when the Na2O content is 0.03%,
% (Comparative Example 9.10), the contents of Na ions and Cl ions are 10 ppm and ippm, respectively.
When the amount was higher (Comparative Examples 7 and 8), the moisture resistance of the composition was extremely poor, but it was confirmed that the composition of the present invention (Example 5) had good fluidity and moisture resistance.

[Example 6] 0.8 parts of triphenylphosphine with a purity of 99% was used instead of 0.75 parts of 2-phenylimidazole as a curing accelerator.
An epoxy resin composition having the same composition as in Example 5 was prepared except that 0 part was used.

When the properties of this epoxy resin composition were measured by the above method, it was found to have a spiral flow value of 31 inches, AQ wiring corrosion of 0%, and good fluidity and moisture resistance.

Applicant: Shin-Etsu Chemical Co., Ltd. Agent: Patent Attorney Takashi Kojima

Claims (1)

[Claims] 1. The purity is 99.5% or more and the Na_2O content is 0.
03% or less and when extracted with water at 100°C
A ion content is 5 ppm or less, Cl ion content is 1
ppm or less, and the average particle size is 5 μm to 60 μm.
1. An epoxy resin composition for semiconductor encapsulation, characterized in that α-alumina having a particle diameter of 250 μm or more and containing 1% or less of particles with a particle size of 250 μm or more is used as a filler.