JPH02265953A - Thermosetting epoxy resin composition and cured product - Google Patents

Abstract

PURPOSE:To obtain the title composition which can give a cured product having a good thermal conductivity, low wearability and a low local stress and can be desirably used for sealing semiconductors, etc., by using synthetic rock crystal of a mean particle diameter <=a specifiedmum as the filler. CONSTITUTION:Synthetic rock crystal of a mean particle diameter <=200mum is used as the following filler in the production of the title composition by mixing an epoxy resin with a curing agent, the above filler and optionally a cure accelerator, a mold release, a pigment, a silane coupling agent, etc. In this way, a thermosetting epoxy resin composition which can give a cured product having a good thermal conductivity, low wearability and a low local stress and can be desirably used for sealing semiconductors, etc., can be obtained.

Description

[Detailed Description of the Invention] The present invention provides a cured product with good thermal conductivity, low abrasion, and low local stress, and can be suitably used for sealing semiconductor devices, etc. The present invention relates to a thermosetting epoxy resin composition and a cured product thereof.

Until now, most thermosetting epoxy resin compositions with high thermal conductivity have used crystalline silica as a filler, but crystalline silica is made from natural silica. Because it is produced by pulverizing silica, its purity is insufficient and it often contains radioactive elements such as uranium.For this reason, epoxy resin compositions containing crystalline silica as a filler are
Uranium, etc. in crystalline silica tends to cause soft errors in highly integrated ICs such as memories after being sealed with resin.

In addition, recently, fine ceramics such as silicon nitride, alumina, boron nitride, and aluminum nitride have been used as fillers in epoxy resin compositions instead of crystalline silica. It has the property of being easily hydrolyzed, and its purity is not sufficient, so there is still room for improvement.

Furthermore, since crystalline silica and fine ceramics are both hard and the tips of their powders are sharp, epoxy resin compositions containing these as fillers suffer from severe mold wear during molding, and are difficult to encapsulate semiconductors. In some cases, the sharp tips of crystalline silica or fine ceramic powders may pierce the device surface and destroy the device.

Therefore, it is desired to develop a thermosetting epoxy resin composition that does not cause mold wear or device destruction and provides a cured product of high quality and high thermal conductivity.

The present invention was made in view of the above circumstances, and provides a thermosetting material that has good thermal conductivity, is less abrasive, and has less local stress, and can be suitably used for sealing semiconductor devices. The purpose of the present invention is to provide an epoxy resin composition and a cured product thereof.

In order to achieve the above object, the inventors of the present invention have conducted intensive studies on fillers to be added to thermosetting epoxy resin compositions, and have found that synthetic quartz crystals with an average particle size of 200 or less contain uranium. A thermosetting epoxy resin composition containing this synthetic crystal, which is easily available as a high-purity product with an amount of 0.5 ppb or less, and has a crystalline structure so that the tips of the crushed particles are unlikely to become sharp. has the same high thermal conductivity as a composition containing crystalline silica in the same amount, and also prevents mold wear during molding and device destruction during resin sealing of semiconductors, etc. , less abrasive,
It was discovered that a cured product with small local stress can be obtained, and the present invention was completed.

Therefore, in the present invention, the filler has an average particle size of 200 Im.
A thermosetting epoxy resin composition containing the following synthetic crystals and a cured product obtained by curing the same are provided.

The present invention will be explained in more detail below.

The thermosetting epoxy resin composition 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, 1. If the epoxy resin constituting the composition of the present invention has two or more epoxy groups in one molecule and can be cured with various curing agents as described below, its molecular structure and molecular weight should be determined. There are no particular restrictions on the epoxy resin, and various conventionally known epoxy resins can be used. For example, epoxy resins synthesized from epichlorohydrin and various novolac resins including bisphenol, Examples include epoxy resins, epoxy resins into which halogen atoms such as chlorine atoms and bromine atoms are introduced, and among these, substituted or unsubstituted novolak epoxy resins and bisphenol A epoxy resins are particularly preferably used. Note that these epoxy resins may be used alone or in combination of two or more.

Furthermore, epoxy resins have an organic acid content of 1100 pp or less, especially when used for sealing semiconductors.

In particular, 50PP- or less, chlorine ions are 2 ppm or less, especially 1 ppm or less, and the content of hydrolyzable chlorine is 50 ppm or less.
It is preferable to use one having an epoxy equivalent of 0 ppm or less, particularly 1100 pp or less, and an epoxy equivalent of 180 to 230, particularly 180 to 200, thereby further improving moisture resistance.

Furthermore, there is no problem in appropriately using a monoepoxy compound together with the epoxy resin, and examples of the monoepoxy compound include styrene oxide, cyclohexene oxide, propylene oxide, methyl glycidyl ether, ethyl glycidyl ether, butenyl glycidyl ether, allyl glycidyl ether, and octyl glycidyl ether. Examples include ren oxide and dodecene oxide.

In addition, curing agents are used depending on the type of epoxy resin, and for example, acid anhydrides such as trimellitic anhydride and tetrahydrophthalic anhydride, phenolic resins, etc. are used, but among them, phenolic resins, especially those with the following average structure A novolac type phenol resin obtained by reacting a phenol represented by the formula (%) with formalin using an acid catalyst can be suitably used.

In addition, when using the phenol resin for semiconductor encapsulation, free Na, CI2
below 2 ppm, especially below 1 ppm, the amount of free phenol below 1%, especially below 0.2%, the amount of organic acid below 1100 ppm, especially below 50 ppm, and the softening point below 5
0 to 120°C, preferably 80 to 100°C, 7-mer phenol contained in phenolic resin,
That is, if the amount of free phenol exceeds 1%, it may have an adverse effect on moisture resistance, and when molded products are made from this composition, defects such as voids, unfilling, whiskers, etc. may occur in the molded products. Furthermore, if the amount of organic acid such as formic acid produced by the Cannitzaro reaction of trace amounts of formaldehyde remaining during the production of the phenolic resin exceeds 1100 pp, the moisture resistance of the semiconductor may be poor. Furthermore, if the softening point of the phenol resin is less than 50°C, the glass transition point will be low, resulting in a decrease in heat resistance and moisture resistance, and if it exceeds 1.20°C, the melt viscosity of the epoxy resin composition will increase, resulting in poor workability. , and moisture resistance may decrease.

Here, the blending amount of the curing agent is not particularly limited.

When using a phenolic resin as a hardening agent, the yield is 15 parts by weight per 100 parts (parts by weight, same hereinafter) of the epoxy resin.
~70 copies.

In addition to or in place of the novolak type phenol resin, the phenol resin may include phenol-purfural resin, resorcinol-formaldehyde resin, organopolysiloxane-modified phenol resins thereof, and natural resin-modified phenol resins.

There is no problem in using a natural oil-modified phenol resin or the like in combination as appropriate.

Furthermore, it is preferable to incorporate a curing accelerator into the composition of the present invention in order to promote the reaction between the epoxy resin and the curing agent. As the curing accelerator, compounds normally used for curing epoxy resins, such as imidazole or its derivatives,
Tertiary amine derivatives, organic phosphine compounds, cycloamidine derivatives, etc. are used, but organic phosphine compounds and cycloamidine derivatives are particularly preferred from the viewpoint of moisture resistance of the composition.

Note that specific examples of the organic phosphine compound include triphenylphosphine, tricyclohexylphosphine, methyldiphenylphosphine, triparatolylphosphine, and the like, and one or more of these can be used. In the present invention, the purity of the organic phosphine compound is not particularly limited, but triphenylphosphine with a purity of 98% or more is preferably used.

In addition, as a cycloamidine derivative, in particular, 1゜8-diaza-bicyclo[5゜4.0]undecene-7 (hereinafter referred to as
(abbreviated as DBU) is desirable, and its purity is 99% or more,
In particular, it is preferable to use 99.8% or more.
The use of such high purity DBU provides better moisture resistance properties of the composition.

Here, the blending amount of the curing accelerator is preferably 0.2 to 5 parts per 100 parts of the total amount of the epoxy resin and the curing agent. In particular, when using an organic phosphine compound as the curing accelerator, It is preferable that the amount of the organic phosphine compound is 0.5 to 5 parts, particularly 0.6 to 2 parts, per 100 parts of the total amount of the epoxy resin and curing agent, and when DBU is used as a curing accelerator. is 1. D B U
It is preferable that the amount of the curing accelerator is 0.2 to 4 parts, particularly 0.5 to 2 parts, per 100 parts of the total amount of the epoxy resin and curing agent.If the amount of the curing accelerator is less than the above range, the epoxy The curability and moisture resistance of the resin composition may be inferior.
Moreover, if the amount exceeds the above range, moisture resistance properties and electrical properties at high temperatures may deteriorate, and the molding defect rate may increase.

In addition, when using DBU, DBU is a strong base,
If DBU is present in a composition in a poor state, its moisture resistance properties tend to deteriorate. Therefore, it is preferable to react DBU with a curing agent such as a phenol resin to form a solid salt compound at room temperature to reduce the basicity of DBU. . This salt compound of DBtJ and a curing agent such as a phenol resin can be synthesized either in a solution or by a melt reaction.

The thermosetting epoxy resin composition of the present invention contains a specific synthetic crystal as a filler, along with optional components such as the epoxy resin described above, a curing agent, and a curing accelerator.

Here, 1 synthetic crystal has an average particle size of 200μ or less,
Preferably, those having a particle size of 5 to 20 μm and a maximum particle size of 100 μm or less are used. If the average particle size of the synthetic quartz crystal is larger than 200 mm, one synthetic quartz particle is too large and causes clogging of the gate of the mold, making it unsuitable as a filler.

Note that 1. Synthetic quartz can be synthesized from silicon tetrachloride, tetraalkoxysilane, water glass, etc. by a wet method, etc., and can be easily made into a powder with the above particle size by adjusting manufacturing conditions or pulverizing after synthesis. can do. Also,
The synthetic quartz crystal obtained in this way has a crystalline structure, and unlike silica stone, it is difficult to produce crushed particles with sharp edges even when crushed (reference photo).

Furthermore, it is preferable to use a synthetic crystal with an aspect ratio of 1.2 to 5, particularly 1.2 to 3. If a synthetic crystal with such an aspect ratio is used as a filler, the composition can be improved without deforming the bonding wire. can mold things,
Moreover, thermal shock resistance can also be significantly improved.

Furthermore, since synthetic crystal is a synthetic product, it is easily available, and it is highly pure and can easily control radioactive elements such as uranium and thorium to 0.5 ppb or less. The thermosetting epoxy resin composition of the present invention used as a filler is suitable for semiconductor encapsulation.

In this case, the amount of the synthetic crystal added is 100 to 1,000 parts, especially 25 parts to 100 parts of the total amount of the epoxy resin and curing agent.
It is preferable to set it as 0-800 parts.

If the amount added is less than 100 parts, the thermal conductivity of the composition may become insufficient, and if it exceeds 1000 parts, the fluidity of the composition may deteriorate and the moldability may deteriorate.

In the present invention, in addition to the above-mentioned synthetic quartz as a filler, crystalline silica, fused silica,
Inorganic fillers such as alumina, silicon nitride, aluminum nitride, boron nitride, and various inorganic fibers may be used in combination.

In addition, it is desirable to use these inorganic fillers after surface treatment with a silane coupling agent etc.
Examples of the silane coupling agent include epoxysilane such as γ-glycidoxytrimethoxysilane, aminosilane such as aminopropyltrimethoxysilane, methyltrimethoxysilane, phenyltrimethoxysilane, and trimethylmethoxysilane. A titanium-based coupling agent or an aluminum-based coupling agent may be used in conjunction with the ring agent. The amount of coupling agent used and the surface treatment method can be the same as usual.

The composition of the present invention may further contain various additives depending on its purpose, use, etc., if necessary. For example, waxes, fatty acids such as stearic acid, mold release agents such as metal salts thereof, pigments such as carbon black, dyes, flame retardants, anti-aging agents, and other additives may be incorporated.

Note that the use of well-refined carnauba wax as a mold release agent is effective in increasing the adhesive strength of the composition of the present invention to nickel.

The composition of the present invention can be obtained by a method such as uniformly stirring and mixing the required amounts of the above-mentioned components, heating the mixture to 70 to 95°C in advance, mixing with a roll, kneader, etc., cooling, and pulverizing. Can be done. Note that there is no particular restriction on the component formulation J111A.

The epoxy resin composition of the present invention is applicable to ICs and LSIs.

Suitable for use in sealing semiconductor devices such as transistors, thyristors, and diodes, and manufacturing printed circuit boards. Note that when sealing the semiconductor device, conventionally employed molding methods such as transfer molding, injection molding, and casting methods can be employed. In this case, the molding temperature of the epoxy resin composition is 1
It is preferable to carry out post-curing at 50-180°C for 2-16 hours at 150-180°C.

The thermosetting epoxy resin composition of the present invention provides a cured product with good thermal conductivity, low abrasion, and low local stress, and is suitable for use in sealing semiconductor devices, etc. Can be used for

[Example, comparative example]

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 are parts by weight.

[Example 1] 60 parts of cresol novolak type epoxy resin (EOCN I O27, Nippon Kayaku Co., Ltd. II) with an epoxy equivalent weight of 196, 30 parts of phenol novolac resin (TD2093, manufactured by Dainippon Ink Co., Ltd.), brominated epoxy resin (BREN, Nippon Kayaku Co., Ltd.) 10 copies.

The average particle size is 18. , the maximum grain size is 100-, the aspect ratio is 1.0 to 4.5, and the length of the major axis is 1.50-
Below, 475 parts of synthetic crystal with a short axis length of 50 μ or less, 1.5 parts of carnauba wax, 1.5 parts of γ-glycidoxytrimethoxysilane (KBM403° Shin-Etsu Chemical Co., Ltd. 1 t),
1.0 part of methyltrimethoxysilane (KBM13, manufactured by Shin-Etsu Chemical Co., Ltd.), 1.0 part of carbon black, 8 parts of antimony dioxide, and 0.8 part of triphenylphosphine were mixed uniformly in a Henschel mixer, and then heated to 95°C. A thermosetting epoxy resin composition was obtained.

[Examples 2 and 3, Comparative Examples 1 and 2] Example 1 except that the amount of synthetic quartz added was changed as shown in Table 1, and the required amounts of crystalline quartz and fused silica were added.
A thermosetting epoxy resin composition was prepared in the same manner.

Next, the above thermosetting composition was evaluated by the following method.

The results are also listed in Table 1.

[Measurement of mold wear amount]

The gate part of the transfer molding mold is made of brass, and 5
After continuous molding 0 times, the amount of wear was evaluated based on the amount of weight loss with respect to the initial weight of the gate portion.

[Crack resistance]

9. Glue a silicon chip with a size of 4 x 5 x 0.5 m to a 14 PIN-IC frame (42 alloy),
An epoxy resin composition was molded onto this under molding conditions of 175°C x 2 minutes, and after post-curing at 180°C for 4 hours, -1,
A thermal cycle of 96° C. x 1 minute to 260° C. x 30 seconds was repeated, and the crack failure rate after 50 cycles was examined.

[Moisture resistance]

14 P I N-D N test elements for moisture resistance measurement
Mold with P and place in a high pressure cooker at 121℃ and 100% humidity.
000 hours, and the open failure rate of the wiring was investigated.

[Method for measuring passivation cracks] A test element using silicon dioxide as passivation is 16PI.
Mounted on N-DIP and molded the epoxy resin composition under molding conditions 1.
After molding at 75°C for 2 minutes and post-curing at 180°C for 4 hours.

A thermal cycle of -196°C for 1 minute and 150°C for 30 seconds was repeated, and the crack failure rate after 150 cycles was examined.

Based on the results in Table 1, crystalline silica is blended (Comparative Example 1
), the mold wear is large, the crack resistance and moisture resistance are poor, and the one containing fused silica (Comparative Example 2) has low thermal conductivity. The curable epoxy resin compositions (Examples 1 to 3) have high thermal conductivity equivalent to that when crystalline silica is used (Comparative Example 1), and are cured products with low abrasion and low local stress. It has been confirmed that it will give.

Applicant: Shin-Etsu Chemical Co., Ltd.

Claims (1)

[Scope of Claims] 1. A thermosetting epoxy resin composition characterized in that it contains synthetic quartz crystals having an average particle size of 200 μm or less as a filler. 2. A cured product obtained by curing the composition according to claim 1.