JP5576700B2 - Epoxy resin composition for semiconductor encapsulation and semiconductor device - Google Patents

Description

  The present invention relates to an epoxy resin composition for semiconductor encapsulation and a semiconductor device encapsulated thereby.

  Due to the high integration of semiconductors, the package structure is becoming more complex, and the gold wire has a smaller diameter and fine pitch. Along with this trend, the epoxy resin composition used for semiconductor encapsulation is required to have high fluidity, that is, low viscosity that does not cause unfilling or wire deformation. At the same time, in order to suppress warping of the package in PBGA and FBGA by reducing the viscosity, it is necessary to increase the filling amount of the inorganic filler to suppress the molding shrinkage.

  Therefore, conventionally, a bisphenol type crystalline epoxy resin has been used as a relatively low molecular weight phenol type crystalline epoxy resin as a means for reducing the viscosity at the time of melting, and t-adjacent positions of the glycidyl ether group are t. An attempt has been made to use a phenol type epoxy resin having a sterically hindered hydrocarbon group such as a butyl group (for example, see Patent Documents 1 and 2).

Japanese Patent No. 669526 JP 2002-294036 A

  However, in the case of the above-mentioned bisphenol type crystalline epoxy resin, although the melt viscosity is low, the melting point is generally low and it is difficult to recrystallize, and the resin composition after kneading is soft, difficult to grind, and easy to block. There is a problem. On the other hand, in the above-mentioned phenol type epoxy resin having a sterically hindered hydrocarbon group, a composition having a low melt viscosity can be expected, but the melting point is high, and the resin composition is uniform during melt kneading at a temperature of about 80 to 120 ° C. However, it is difficult to melt and disperse.

  From this background, the present invention exhibits low viscosity and high fluidity at the time of melting, suppresses the occurrence of defects such as unfilling and wire deformation, and at the same time enables high filling of inorganic fillers and reduces package warpage. It can be uniformly dispersed during melt-kneading, and the resin composition after kneading is hard and can be pulverized by a pulverizer. It is an object of the present invention to provide an epoxy resin composition for semiconductor encapsulation which can make blocking of tablet adhesion difficult to occur, and a semiconductor device encapsulated thereby.

The epoxy resin composition for semiconductor encapsulation of the present invention contains (A) an epoxy resin, (B) a curing agent, (C) a curing accelerator, and (D) an inorganic filler.
(A) Molten mixture of (Aa) bisphenol type crystalline epoxy resin and (Ab) phenol type epoxy resin having a sterically hindered hydrocarbon group, each in the range of 10 to 90% by mass of the total amount as an epoxy resin Is blended,
(B) As a curing agent, only a phenol resin-based curing agent composed of at least one selected from the group consisting of a phenol novolak resin, a cresol novolak resin, a phenol aralkyl resin, a biphenyl aralkyl resin, and a dicyclopentadiene skeleton-containing phenol resin is blended. As
(D) The inorganic filler is blended in the range of 85 to 92% by mass with respect to the total amount of the composition.

Further, molten mixture of a phenol type epoxy resin having a (Aa) a bisphenol type crystalline epoxy resin and (Ab) sterically hindered hydrocarbon group, the weight ratio of the mutual 1: 3 to 3: 1.

  In addition, (Aa) bisphenol type crystalline epoxy resin has the following formula (1):

(In the formula, X represents CH ₂ or C (CH ₃ ) _2. )
That is represented by
And (Ab) a phenol type epoxy resin having a sterically hindered hydrocarbon group is represented by the following formula (2):

It is characterized by being represented by.

  The present invention also features a semiconductor device sealed with any of the above epoxy resin compositions.

  According to the epoxy resin composition for semiconductor encapsulation of the present invention, it exhibits low viscosity and high fluidity when melted, suppresses the occurrence of defects such as unfilling and wire deformation, and at the same time enables high filling of inorganic fillers. It is possible to reduce the warpage of the package, and it is possible to uniformly disperse at the time of melt kneading, and the resin composition after kneading is hard and can be pulverized by a pulverizer. Or blocking of tablet adhesion after tableting can be made difficult to occur.

  In the epoxy resin composition for semiconductor encapsulation of the present invention, as the (A) epoxy resin, a molten mixture of (Aa) a bisphenol type crystalline epoxy resin and (Ab) a phenol type epoxy resin having a sterically hindered hydrocarbon group is used. Addition blended. The ratio of each of the molten mixture to the total amount of (A) epoxy resin is in the range of 10 to 90% by mass.

  This molten mixture is added and blended, and is kneaded with (B) a curing agent, (C) a curing accelerator, and (D) an inorganic filler in a proportion of 85 to 92% by mass with respect to the total amount of the composition. An epoxy resin composition for stopping is prepared. Thus, as at least a part of the essential component (A) epoxy resin, (Aa) a molten mixture of a bisphenol type crystalline epoxy resin and (Ab) a phenol type epoxy resin having a sterically hindered hydrocarbon group is added and blended It is extremely important to do this, and it is an indispensable requirement.

  Examples of (Aa) bisphenol-type crystalline epoxy resins include 4,4′-bis (2,3-epoxypropoxyphenyl) methane, 2,4′-bis (2,3-epoxypropoxyphenyl) methane, 3, Examples include 3 ′, 5,5′-tetramethyl-4,4′-bis (2,3-epoxypropoxyphenyl) methane. One or more of these are used. Examples of the (Ab) phenolic epoxy resin having a sterically hindered hydrocarbon group include 2,5-di-tert-butyl-1,4-bis (2,3-epoxypropoxy) benzene, 2,3, Examples include 5,6-tetramethyl-1,4-bis (2,3-epoxypropoxy) benzene. One or more of these are used.

  However, the (Aa) bisphenol-type crystalline epoxy resin itself alone generally has a low melting point and is difficult to recrystallize, and the blended composition after kneading is soft, difficult to grind, and easily blocked. On the other hand, the (Ab) phenol type epoxy resin itself having a sterically hindered hydrocarbon group itself generally has a high melting point and is difficult to dissolve and disperse in the composition during melt-kneading (at a temperature of about 80 to 120 ° C.). The above problems can be solved by simply mixing the (Aa) and (Ab) epoxy resins with the (B) curing agent, (C) curing accelerator, and (D) inorganic filler. It is hard to be done. (Aa) (Ab) Both epoxy resins are melted and mixed in advance, and the resulting molten mixture is combined with (B) a curing agent, (C) a curing accelerator, and (D) an inorganic filler. It is necessary to mix and melt knead.

  As a result, when melted, it exhibits low viscosity and high fluidity, suppresses the occurrence of defects such as unfilling and wire deformation, and at the same time enables high filling of inorganic fillers and enables reduction of package warpage. The resin composition after kneading can be uniformly dispersed during melt-kneading, and the resin composition after kneading is hard and can be pulverized by a pulverizer, resulting in blocking of powder after pulverization and tablet adhesion after tableting. Can be difficult.

  The molten mixture of (Aa) bisphenol type crystalline epoxy resin and (Ab) phenol type epoxy resin having a sterically hindered hydrocarbon group has a mass ratio of 1: 3 as (Aa) :( Ab). More preferably within the range of 3: 1. When the ratio (Aa) is too small and the ratio (Ab) is excessive, the melting point becomes high and it becomes difficult to melt uniformly during kneading.

  On the other hand, in the opposite case, the molten mixture is difficult to crystallize and may be difficult to grind.

  Preparation of a molten mixture is possible by melt-mixing above the melting temperature of the (Ab) epoxy resin having a higher melting point. Uniform melt mixing is possible.

  As for (Aa) bisphenol-type crystalline epoxy resin, for example, those represented by the above formula (1) are more preferable from the viewpoints of availability, the effect of reducing the viscosity, and the sealing properties of the semiconductor. It is done. As this product, for example, a commercially available product as Japan Epoxy Resin YL6810 (melting point: 45 ° C.) can be used. Moreover, as (Ab) phenol type epoxy resin which has a sterically hindered hydrocarbon group, what is represented, for example by said Formula (2) is mentioned as a more suitable thing. This can use a commercial item as, for example, Toto Kasei YDC1312 (melting point 142 ° C.).

  (A) An epoxy resin other than the above (Aa) and (Ab) can be added to the epoxy resin. For example, one or more of a biphenyl type epoxy resin, a biphenyl aralkyl type epoxy resin, and other various types may be included.

  (B) About a hardening | curing agent, the mixing | blending of a phenol resin type hardening | curing agent is essential. Here, the phenol resin-based curing agent means one having a phenolic hydroxyl group. For example, specific examples include novolak resins such as phenol novolak resin, cresol novolak resin, naphthol novolak resin, tris (hydroxyphenyl) methane, 1,1,2-tris (hydroxyphenyl) ethane, 1,1,3-tris. Examples thereof include phenol aralkyl resins such as (hydroxyphenyl) propane, biphenyl aralkyl resins, terpene and phenol condensation compounds, dicyclopentadiene skeleton-containing phenol resins, and naphthol aralkyl resins.

  About the compounding ratio with respect to (A) epoxy resin of these (B) hardening | curing agents, it is generally set as the range of 0.2-0.8 as (B) / (A) as mass ratio. It is considered.

  Moreover, about (C) hardening accelerator, it is generally considered that it shall be in the range of 0.01-0.1 as mass ratio (C) / (A) with respect to (A) epoxy resin. Various curing accelerators may be used. For example, phosphine compounds such as triphenylphosphine, trimethylphosphine, triethylphosphine, tributylphosphine, tri (p-methylphenyl) phosphine, tri (nonylphenyl) phosphine and their salts, 2-methylimidazole, 2,4-dimethylimidazole 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-heptadecylimidazole, triethylamine, benzyldimethylamine, dimethylbenzylmethylamine, 2- (dimethylaminomethyl) phenol, Amine compounds such as 2,4,6-tris (dimethylaminomethyl) phenol and 1,8-diazabicyclo (5,4,0) undecene-7 are preferably used in terms of moldability and reliability. But it is not particularly limited as long as it promotes the curing reaction.

  The type of (D) inorganic filler is not particularly limited. For example, as specific types, it is preferable to use fused silica, crystalline silica, calcium carbonate, magnesium carbonate, alumina, and the like, and fused silica and crystalline silica are more preferable from the viewpoint of moldability and reliability. Moreover, two or more types of inorganic fillers can be used in combination depending on the application. Specifically, as the inorganic filler to be used in combination, fused silica, crystalline silica, calcium carbonate, magnesium carbonate, alumina, magnesia, clay, Examples include talc, calcium silicate, titanium oxide, asbestos, and glass fiber. The average particle size of the inorganic filler is preferably 0.5 to 40 μm.

  However, (D) About the compounding quantity of an inorganic filler, it shall exist in the range of 85-92 mass% with respect to the whole quantity of the epoxy resin composition for semiconductor sealing of this invention. If it is less than 85% by mass, it becomes difficult to suppress the warpage of the package as well as the characteristics for sealing. On the other hand, when it exceeds 92 mass%, it becomes difficult to ensure the fluidity and moldability of the composition.

  In the present invention, in addition to the above, if necessary, silane coupling agents such as γ-glycidoxypropyltrimethoxysilane and γ-mercaptopropyltrimethoxysilane, carnauba wax, stearic acid and its derivatives, montanic acid And derivatives thereof, carboxyl group-containing agents, dyes, modifiers, plasticizers, diluents, and the like.

  The epoxy resin composition for semiconductor encapsulation of the present invention is not particularly limited in its preparation method as long as it can uniformly disperse and mix essential components and other optional components. An example is a method in which an amount of components are sufficiently mixed by a mixer or the like, and then melted and mixed by heating with a mixing roll or kneader as needed to cool and solidify. At this time, the pulverized composition can be made into a tablet with a size and weight suitable for molding conditions using a tableting machine.

  In the resin-encapsulated semiconductor device of the present invention, semiconductor elements such as integrated circuits, large-scale integrated circuits, transistors, thyristors, and diodes and / or semiconductor integrated circuits are encapsulated with a cured product of the epoxy resin composition of the present invention. There are no particular limitations on the type of semiconductor element and / or semiconductor integrated circuit, sealing method, package shape, and the like.

  As a general method of sealing, a low-pressure transfer molding method can be mentioned, but sealing can also be performed by injection molding, compression molding, casting, potting or the like. The curing conditions at the time of molding and / or after molding vary depending on the type of each component of the epoxy resin composition and the blending amount, but are usually 30 seconds to 10 hours at a temperature of 150 to 220 ° C.

  A semiconductor device sealed by a transfer molding method or the like is mounted on an electronic device or the like as it is or after being completely cured at a temperature of 80 to 200 ° C. for 15 seconds to 10 hours.

  Therefore, an example will be shown below and will be described in more detail. Of course, the present invention is not limited to the following examples.

(Examples 1-6) (Comparative Examples 1-4)
The epoxy resin melt mixture added and blended in Examples 1 to 6 weighed the epoxy resin (Aa) and the epoxy resin (Ab) at a predetermined ratio (5/5, 3/1, 1/3). The mixture was melted and stirred at 150 ° C.

  After both were uniformly mixed, it was cooled and ground.

  The epoxy resin compositions of Examples 1 to 6 and Comparative Examples 1 to 4 were weighed so that each component had the ratio shown in Table 1, and uniformly dispersed using a mixer, and then kneaded with a kneader. It was prepared by pulverizing after cooling.

  In addition, the following were used about each component shown in Table 1.

  (Aa) As a bisphenol-type crystalline epoxy resin, YL6810 made by JER represented by the above formula (1) was used.

  (Ab) As a phenol type epoxy resin having a sterically hindered hydrocarbon group, YDC1312 manufactured by Tohto Kasei Co., Ltd. represented by the above formula (2) was used.

  As a biphenyl type epoxy resin of a comparative example, YX4000H made by JER was used.

  Meiwa Kasei H-1M was used as a phenol novolac resin as a curing agent.

  Tetraphenylphosphonium tetraphenylborate (Hokuko Chemical Co., Ltd. TPP-K) was used as a curing accelerator.

  Spherical fused silica having an average particle size of 15 μm was used.

The following evaluation was performed about the obtained epoxy resin composition.
<Melt viscosity>
It measured at 175 degreeC using the Koka type flow tester.
<Blocking property>
The kneaded resin composition was pulverized and allowed to stand at room temperature for 2 hours. The adhesion between particles was observed.
<Tablet appearance defect>
The appearance defect when tableting on a tablet was visually evaluated. The case where there was no problem was shown as ◯, and the case where unmelted crystals of the epoxy resin component were observed was shown as ×.
<Wire deformation rate>
A chip was mounted on a 35 × 35 mm PBGA substrate, a gold wire having a diameter of 20 μm and a length of 5 mm was applied, and the deformation rate (maximum deformation amount / wire length) of the gold wire after transfer molding of the resin composition was measured. .
<Package warpage>
The warpage of the resin-sealed surface of the PBGA was measured using a surface roughness meter, and the average value of the maximum warpage amount of the diagonal line was obtained.

  The results of these evaluations are also shown in Table 1.

  As is clear from the comparison with the comparative examples, Examples 1 to 6 in which a molten mixture of (Aa) a bisphenol type crystalline epoxy resin and (Ab) a phenol type epoxy resin having a sterically hindered hydrocarbon group is added and blended. Good results were obtained for all of the evaluation items. The melt viscosity is 14 Pa. The viscosity was s or less, and the blocking property and tablet appearance were also good. It can also be seen that the wire deformation rate is small and the package warpage is small.

Claims (2)

(A) an epoxy resin, (B) a curing agent, (C) a curing accelerator, and (D) an epoxy resin composition for semiconductor encapsulation containing an inorganic filler,
(A) Molten mixture of (Aa) bisphenol type crystalline epoxy resin and (Ab) phenol type epoxy resin having a sterically hindered hydrocarbon group, each in the range of 10 to 90% by mass of the total amount as an epoxy resin Is blended,
The molten mixture has a mutual mass ratio in the range of 1: 3 to 3: 1;
The (Aa) bisphenol type crystalline epoxy resin has the following formula (1):

(In the formula, X represents CH ₂ or C (CH ₃ ) _2. )
Represented by
The (Ab) phenol type epoxy resin having a sterically hindered hydrocarbon group is represented by the following formula (2):

Represented by
(B) As a curing agent, only a phenol resin-based curing agent composed of at least one selected from the group consisting of a phenol novolak resin, a cresol novolak resin, a phenol aralkyl resin, a biphenyl aralkyl resin, and a dicyclopentadiene skeleton-containing phenol resin is blended. As
(D) The epoxy resin composition for semiconductor sealing characterized by the inorganic filler being mix | blended within the range of 85-92 mass% with respect to the composition whole quantity.   A semiconductor device which is sealed with the epoxy resin composition according to claim 1.