JP2005146229A - Epoxy resin composition for sealing and semiconductor device by using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an epoxy resin composition for sealing, excellent in molding property and reliability without damaging flame retardant property, having high thermal conductivity, a low thermal expansion coefficient, excellent in heat resistance and capable of reducing the warpage of a package, and further a semiconductor device by using the same. <P>SOLUTION: This epoxy resin composition for sealing consists of an epoxy resin, a curing agent and an inorganic filler as essential components, it is necessary that the inorganic filler has a spherical outer shape, ≥5 W/m×K heat conductivity and 80-95 mass% content, and also the cured material of the epoxy resin composition for sealing has characteristics of (A) ≥3 W/m×K thermal conductivity, (B) ≤13 ppm linear expansion coefficient α1 and (C) ≥185°C glass transition temperature. Also, the content of a multi-functional epoxy resin in the epoxy resin composition for sealing is desirably ≤5 mass%. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an epoxy resin composition for sealing a semiconductor device, and also relates to a semiconductor device using the same.

  Conventionally, as a sealing method for electrical and electronic parts such as diodes, transistors, and integrated circuits, and semiconductor devices, for example, a sealing method using an epoxy resin or a silicon resin, or a hermetic sealing method using glass, metal, ceramic, or the like has been used. In recent years, resin sealing by transfer molding, which can be mass-produced with improved reliability and cost-effective, has been the mainstream in recent years.

  In the resin composition used for the resin sealing method by the transfer molding, a sealing material made of an epoxy resin and a resin composition mainly containing a phenol resin as a curing agent is generally used.

  Currently, an epoxy resin composition used for the purpose of protecting an element such as a power device is filled with an inorganic filler such as crystalline silica at a high density in order to cope with a large amount of heat released from the element.

  In recent years, power devices are becoming more intelligent by incorporating IC technology, for example, one-chip devices and module types, which further improve heat dissipation and thermal expansion properties for sealing materials. Improvement is desired.

  In order to meet these requirements, the content of amorphous silica is increased to reduce the thermal expansion coefficient, and crystalline silica, silicon nitride, and aluminum nitride are used to improve the thermal conductivity (Patent Document 1). Attempts have been made to use spherical alumina powder (Patent Document 2), but if the content of the inorganic filler is increased, the fluidity decreases with increasing viscosity during molding, and the moldability is impaired. Occurs.

  Furthermore, large-capacity power devices and ICs are modularized and sealed, so the sealing area is enlarged, and in order to improve heat dissipation characteristics, there are large heat-dissipating fins that are sealed with resin on one side. In these packages, there is a problem that warpage is likely to occur due to the influence of so-called molding shrinkage during molding and curing of the resin composition.

  In order to reduce this warpage, it is important to reduce molding shrinkage and raise the glass transition temperature. As a method for this, glass is produced by using a polyfunctional resin and using a highly active curing catalyst. A technique (Patent Document 3) is disclosed that raises the transition temperature, reduces the molding shrinkage, and reduces the warpage.

However, if a polyfunctional resin is used, the flame retardancy deteriorates, the viscosity becomes high and gold wire flow is likely to occur, and the curing reaction becomes unstable by using a highly active curing catalyst. There was a tendency that the reliability as a sealant was lowered due to a large variation in molecular weight distribution.
JP-A-11-147936 JP2002-309067 JP 2001-055431 A

  Therefore, the object of the present invention is to solve the above-mentioned problems, have excellent moldability and reliability without impairing flame retardancy, have high thermal conductivity, low thermal expansion coefficient, and excellent heat resistance. It is to provide an epoxy resin composition for sealing capable of reducing the warpage of the semiconductor, and further to provide a semiconductor device using the same.

In order to solve the above-mentioned problems, the epoxy resin composition for sealing of the present invention is an epoxy resin composition for sealing containing an epoxy resin, a curing agent, and an inorganic filler as essential components, and the inorganic filler Needs to have a spherical outer shape, a thermal conductivity of 5 W / m · K or more and a content of 80 to 95% by mass, and a cured product of the sealing epoxy resin composition,
A) Thermal conductivity is 3 W / m · K or more B) Linear expansion coefficient α1 is 13 ppm or less C) Glass transition temperature must be 185 ° C. or more.

  In order to solve the above problems, the epoxy resin composition for sealing of the present invention desirably has a polyfunctional epoxy resin content of 5% by mass or less.

  Moreover, in order to solve the said subject, it is desirable that the semiconductor device of this invention is what uses said epoxy resin composition for sealing.

The epoxy resin composition for sealing of the present invention is an epoxy resin composition for sealing containing an epoxy resin, a curing agent, and an inorganic filler as essential components, and the inorganic filler has a spherical outer shape, The thermal conductivity is 5 W / m · K or more and the content is 80 to 95% by mass, and the cured product of the epoxy resin composition for sealing is,
A) Thermal conductivity is 3 W / m · K or higher B) Linear expansion coefficient α1 is 13 ppm or lower C) Glass transition temperature is 185 ° C. or higher, excellent in moldability and reliability, heat conduction A sealing epoxy resin composition having a high rate, a low coefficient of thermal expansion, excellent heat resistance and capable of reducing the warpage of a package is provided.

  The epoxy resin composition for sealing of the present invention is characterized in that the content of the polyfunctional epoxy resin is 5% by mass or less, increases the glass transition temperature without impairing flame retardancy, and reduces molding shrinkage. Thus, warpage can be reduced.

  In addition, a semiconductor device of the present invention is characterized by using the above-mentioned sealing epoxy resin composition, and a semiconductor device having a package with excellent reliability and heat resistance and small warpage is provided.

  The epoxy resin composition of the present invention contains an epoxy resin, a curing agent, and a spherical inorganic filler as essential components. Any epoxy resin may be used as long as it has two or more epoxy groups in one molecule, and an epoxy resin generally used for sealing in a semiconductor device can be used. For example, orthocresol novolac type epoxy resin, biphenyl type epoxy resin, triphenylmethane type epoxy resin, phenol novolac type epoxy resin, bisphenol type epoxy resin, dicyclopentadiene type epoxy resin, epoxy resin having naphthalene ring, etc. it can. In order to impart flame retardancy, a halogen-containing epoxy resin containing halogen such as bromine may be used in combination.

  The epoxy resin composition of the present invention can contain a polyfunctional epoxy resin in the range of 5% by mass or less. By containing a polyfunctional epoxy resin, it is possible to increase the glass transition temperature of the cured epoxy resin, reduce molding shrinkage, and obtain an effect of reducing warpage. However, as will be described later, since the same effect can be achieved by high-density filling with an inorganic filler, the polyfunctional epoxy resin is not an essential component. If it exceeds 5% by mass, the flame retardancy deteriorates, which is not preferable.

  The curing agent that is one of the essential components of the epoxy resin composition of the present invention may be any one as long as it has two or more phenolic hydroxyl groups in one molecule, for example, a phenol novolac resin is typical. However, naphthol resins, dicyclopentadiene type phenol resins, phenol aralkyl resins and the like can be used. These may be used alone or in combination of two or more.

  In the epoxy resin composition of this invention, it is preferable that the compounding ratio of an epoxy resin and a hardening | curing agent is the range of 0.9-1.5 in an epoxy-phenol equivalent ratio. Outside this range, unreacted epoxy groups or phenolic hydroxyl groups remain even after curing, which is not preferable because the reliability of the sealing function is lowered.

  In the epoxy resin composition of the present invention, when a halogen-containing epoxy resin or a polyfunctional epoxy resin is used in combination as an epoxy resin, the blending ratio is determined so that the epoxy-phenol equivalent ratio is in a preferable range based on the epoxy equivalent of each. In addition, when two or more of the above-described curing agents are used in combination, it is also desirable to determine the blending ratio based on their phenol equivalents.

  In the epoxy resin composition of the present invention, it is necessary to blend a spherical inorganic filler. The spherical inorganic filler used needs to have a thermal conductivity of 5 W / m · K or more, and alumina, aluminum nitride, crystalline silica, and the like are preferably used. In addition, for example, fused silica, crystalline silica, or the like may be used in combination as an amorphous inorganic filler regardless of the shape as necessary.

  The addition amount of the spherical inorganic filler used in the present invention needs to be 80 to 95% by mass with respect to the epoxy resin composition. If the addition amount is less than 80% by mass, the intended effects of the present invention such as high thermal conductivity and low thermal expansibility cannot be achieved, and if it exceeds 95% by mass, the viscosity increases and the moldability deteriorates. Absent.

  The inorganic filler used in the present invention needs to have a spherical outer shape. The diameter is preferably as uniform as possible. Thereby, it is easy to take a close-packed structure such as a face-centered cubic structure or a hexagonal close-packed structure, and a sufficient filling amount can be obtained. In the case of a non-spherical shape, when the filling amount is increased, friction between the fillers is increased, and before reaching the above upper limit, the fluidity is extremely lowered to increase the viscosity and the moldability is deteriorated.

  In the epoxy resin composition of the present invention, stability against heat change is achieved by filling a spherical inorganic filler having a high thermal conductivity with a thermal conductivity of 5 W / m · K or more at a high density. improves. That is, an epoxy resin composition for sealing with good heat resistance that exhibits low thermal expansion and a high glass transition temperature of 185 ° C. or higher is obtained.

  In the epoxy resin composition of this invention, the curing catalyst generally used for the epoxy resin composition for sealing can be used. For example, organic phosphorus compounds such as triphenylphosphine and trimethylphosphine, and imidazoles such as 2-methylimidazole, 2-phenyl-4-methylimidazole, 2-phenylimidazole, and 1benzyl-2-phenylimidazole can be exemplified. . Tertiary amines such as 1,8-diazabicyclo (5,4,0) undecene-7, triethanolamine and benzyldimethylamine can also be used. These may be used alone or in combination.

  The addition amount of the curing catalyst is preferably 0.1 to 2.0% by mass with respect to the total of the epoxy resin (including the halogen-containing epoxy resin as a flame retardant) and the curing agent. If it is less than 0.1% by mass, the gelation time is delayed, resulting in a decrease in workability due to a decrease in rigidity at the time of curing. Conversely, if it exceeds 2.0% by mass, curing proceeds during molding and unfilling occurs. It becomes easy to do.

  In the epoxy resin composition of the present invention, a wax can be used as a release agent generally used for an epoxy resin composition for sealing. As the wax, for example, stearic acid, montanic acid, montanic acid ester, phosphoric acid ester and the like can be used.

  In the epoxy resin composition of this invention, in order to improve the adhesive force of an inorganic filler and a resin component, the coupling agent generally used for the epoxy resin composition for sealing can be used. As the coupling agent, for example, epoxy silane can be used. As for the addition amount of a coupling agent, 0.1-2.0 mass% is preferable with respect to the epoxy resin composition for sealing. If it is less than 0.1% by mass, the compatibility between the resin and the base material is poor, and the moldability deteriorates. Conversely, if it exceeds 2.0% by mass, the molded product is soiled by continuous moldability.

  In addition to the above, those that can generally be used in the epoxy resin composition for sealing can be appropriately mixed and used. For example, phosphorus-based flame retardants, flame retardants such as bromine compounds and antimony trioxide, and colorants such as carbon black and organic dyes can be used.

  The epoxy resin composition of the present invention is prepared by uniformly mixing an epoxy resin, a curing agent, an inorganic filler, and other components other than the coupling agent with a mixer, and then adding a coupling agent, a heating roll, a kneader, etc. Kneaded and manufactured. There is no restriction | limiting in particular in the mixing | blending order of components other than a coupling agent. Furthermore, after kneading, the melt-kneaded product can be pulverized to be powdered or tableted.

  The epoxy resin composition of the present invention is particularly used for sealing in semiconductor devices.

  Hereinafter, the present invention will be described with reference to Examples and Comparative Examples. However, the present invention is not limited to the embodiments described herein.

[Evaluation sample prototype]
(Examples 1-5)
After blending the components shown in Table 1 and mixing thoroughly with a mixer, the coupling agent was added, and the mixture kneaded with a heating roll for about 5 minutes was cooled, crushed, and the sealing epoxy of Examples 1 to 5, respectively. A resin composition was obtained.
(Comparative Examples 1 and 2)
After mixing the components shown in Table 1 and mixing well with a mixer, the coupling agent was added and the mixture kneaded for about 5 minutes with a heating roll was cooled and crushed, and the sealing epoxies of Comparative Examples 1 and 2, respectively. A resin composition was obtained.

  The inorganic filler ratio in Table 1 indicates mass% of the inorganic filler with respect to the total amount of the blended components. The polyfunctional epoxy resin content indicates mass% of the polyfunctional epoxy resin with respect to the total amount of components similarly blended.

[Evaluation]
(1) Thermal conductivity Using a mold, the thermal conductivity of the epoxy resin compositions obtained in Examples 1 to 5 and Comparative Examples 1 and 2 was set at a temperature of 175 ° C., an injection time of 10 seconds, and a pressurization time of 100. Second, transfer molding was performed under molding conditions of an injection pressure of 7 MPa, and after-curing at 175 ° C. for 6 hours, a disk-shaped evaluation sample having a diameter of 100 and a thickness of 25 ± 5 mm was produced. The obtained sample for evaluation was measured by the unsteady hot wire method using a QTM-D3 rapid thermal conductivity meter manufactured by Kyoto Electronics Industry Co., Ltd. The results are shown in Table 1.
(2) Linear expansion coefficient, glass transition temperature The linear expansion coefficient is a JIS molded product for performance evaluation using the epoxy resin compositions obtained in Examples 1 to 5 and Comparative Examples 1 and 2, and 175 ° C. And after-curing for 6 hours, and using a measuring device manufactured by Rigaku Denki Co., Ltd., measurement was performed in the temperature range of 50 to 100 ° C. by the TMA compression method. The glass transition temperature is 3 ° C./min. It measured and calculated | required with the temperature increase rate of. The measurement results of the linear expansion coefficient and glass transition temperature are shown in Table 1.
(3) Mold Shrinkage The mold shrinkage was evaluated using the epoxy resin compositions obtained in Examples 1 to 5 and Comparative Examples 1 and 2, at a temperature of 175 ° C., an injection time of 7 seconds, and a pressurization time of 120 seconds. Then, transfer molding was performed under molding conditions of an injection pressure of 7 MPa to produce a JIS molded product, the size of the molded product was measured, and the dimensional ratio with the mold was taken as the molding shrinkage rate. The results are shown in Table 1.
(4) Heat resistance reliability The heat resistance reliability was evaluated by the following method.
The epoxy resin composition obtained in Examples 1 to 5 and Comparative Examples 1 and 2 using a TEG (Test Experimental Group) with 3 μm aluminum wiring and using a 16 DIP (Dual In-line Package) mold The product was transfer molded to produce a molded product. The molding conditions were a temperature of 175 ° C., an injection time of 7 seconds, a pressurization time of 120 seconds, and an injection pressure of 7 MPa. This molded product was after-cured at 175 ° C. for 6 hours to obtain a 16 DIP semiconductor device for performance evaluation. This semiconductor device for performance evaluation was tested under the condition of a temperature cycle (−65 ° C., 30 minutes to 150 ° C., 30 minutes), and the number of 50% defective generation cycles (until 50% of the TEG aluminum wiring was poorly energized) Cycle number = hour). The results are shown in Table 1.

  The epoxy resin composition molded article for sealing of Examples 1 to 4 containing an inorganic filler having a large thermal conductivity is three times or more compared to the molded epoxy resin composition for sealing of Comparative Examples 1 and 2. As a result, it showed a sufficiently excellent result that there was no problem of 3000 cycles in heat resistance reliability.

  On the other hand, the sealing epoxy resin composition molded products of Comparative Examples 1 and 2 having low thermal conductivity of the inorganic filler contained therein had a defect exceeding 50% at 1000 cycles and 1500 cycles, respectively, and were measured at that time. Canceled.

  When Example 1 and Example 2 are compared, a difference in effect due to the difference in the content of the inorganic filler appears, that is, the greater the content of the inorganic filler, the higher the thermal conductivity and the lower the linear expansion coefficient. It can be seen that the glass transition temperature is high and the molding shrinkage is small.

  In Example 3, the content of the inorganic filler is different between Examples 1 and 2, and the type of epoxy resin is different. However, the measurement data of Example 3 may be regarded as intermediate between Example 1 and Example 2. It can be seen that the characteristics are determined by the content of the inorganic filler rather than the type of the epoxy resin.

  In Example 4, the blending amount of the ortho-cresol novolac type epoxy resin used in Example 2 was reduced, and the weight loss was replaced with a polyfunctional epoxy resin. The glass transition temperature increased due to the effect of the polyfunctional epoxy resin. You can see that

  The effect of the polyfunctional epoxy resin is also apparent from the data of Comparative Example 1 and Comparative Example 2, and the glass transition temperature appears as a larger difference than in Examples 2 and 4. This result is due to the difference in the inorganic filler. In the case of Examples 2 and 4, since the original glass transition temperature is high due to the effect of the inorganic filler, it is considered that the effect of the polyfunctional epoxy resin hardly appears.

  Example 5 is a difference in the curing catalyst, and a highly active imidazole catalyst is used as an effective technique for increasing the glass transition temperature, but the glass transition temperature does not change greatly. From this, the stability against heat change is improved by filling the spherical inorganic filler having high thermal conductivity such that the thermal conductivity is 5 W / m · K or more at a high density, and 185 ° C. or more. An epoxy resin composition for sealing having a high glass transition temperature and good heat resistance is obtained.

The epoxy resin composition for sealing of the present invention is an epoxy resin composition for sealing containing an epoxy resin, a curing agent, and an inorganic filler as essential components, and the inorganic filler has a spherical outer shape, The thermal conductivity is 5 W / m · K or more and the content is 80 to 95% by mass, and the cured product of the epoxy resin composition for sealing is,
A) Thermal conductivity is 3 W / m · K or higher B) Linear expansion coefficient α1 is 13 ppm or lower C) Glass transition temperature is 185 ° C. or higher, excellent in moldability and reliability, heat conduction A sealing epoxy resin composition having a high rate, a low coefficient of thermal expansion, excellent heat resistance and capable of reducing the warpage of a package is provided.

  The epoxy resin composition for sealing of the present invention is characterized in that the content of the polyfunctional epoxy resin is 5% by mass or less, increases the glass transition temperature without impairing flame retardancy, and reduces molding shrinkage. Thus, warpage can be reduced.

In addition, a semiconductor device of the present invention is characterized by using the above-mentioned sealing epoxy resin composition, and a semiconductor device having a package with excellent reliability and heat resistance and small warpage is provided.

Claims (3)

An epoxy resin composition for sealing comprising an epoxy resin, a curing agent, and an inorganic filler as essential components, wherein the inorganic filler has a spherical outer shape and has a thermal conductivity of 5 W / m · K or more. The amount is 80 to 95% by mass, and the cured product of the sealing epoxy resin composition is
A) Thermal conductivity is 3 W / m · K or more B) Linear expansion coefficient α1 is 13 ppm or less C) Glass transition temperature is 185 ° C. or more.   The epoxy resin composition for sealing according to claim 1, wherein the content of the polyfunctional epoxy resin in the sealing epoxy resin composition is 5% by mass or less.   A semiconductor device comprising the sealing epoxy resin composition according to claim 1.