JP4040370B2 - Epoxy resin composition and semiconductor device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an epoxy resin composition for semiconductor encapsulation excellent in moldability and a semiconductor device excellent in solder resistance.
[0002]
[Prior art]
In recent years, electronic devices have become smaller, lighter, and higher in performance, and semiconductor elements have been increasingly integrated, and surface mounting of semiconductor devices has been promoted. The demand for things has become increasingly severe. In particular, surface mounting of semiconductor devices has become common, and moisture-absorbed semiconductor devices are exposed to high temperatures during soldering, and cracks are generated in the semiconductor devices due to the explosive stress of vaporized water vapor, or semiconductors Debonding occurs at the interface between the element or lead frame and the cured product of the epoxy resin composition, resulting in defects that greatly impair electrical reliability, and preventing these defects, that is, improving solder resistance, is a major issue. It has become.
[0003]
Various proposals have been made as means for improving the soldering resistance. As typical examples, (1) using a low-viscosity resin component to increase the amount of inorganic filler and reducing the resin component (2) Use of a resin having low hygroscopicity and flexibility, for example, to lower the thermal expansion and moisture absorption of the cured product of the epoxy resin composition. Examples of the low-viscosity resin component include low-viscosity epoxy resins, phenol resins, and crystalline epoxy resins, but those having a low softening point are difficult to handle because they are liquid or semi-solid at room temperature. On the other hand, a biphenyl type epoxy resin typical as a crystalline epoxy resin has a melting point of 100 ° C. or higher and may not be sufficiently melted during kneading and may not be sufficiently dispersed. In addition, biphenyl type epoxy resin tends to be insufficiently cured because of its slow reaction with phenolic resin, which is a curing agent, and the semiconductor device adheres to the mold when released from the mold, or the semiconductor device There were problems with formability such as cracking and chipping. For this reason, an epoxy resin composition excellent in moldability and solder resistance is required.
[0004]
[Problems to be solved by the invention]
The present invention provides an epoxy resin composition for encapsulating a semiconductor that has a fast curing property and excellent properties in moldability and solder resistance, and a semiconductor device in which a semiconductor element is encapsulated using the same.
[0005]
[Means for Solving the Problems]
The present invention
[1] (A) A crystalline epoxy resin represented by formula (1) having a melting point of 40 to 50 ° C. obtained by measurement at a heating rate of 5 ° C./min using a differential scanning calorimeter, formula (B) ( 7) selected from phenol resin represented by (C) 1,8-diazabicyclo (5,4,0) undecene-7, triphenylphosphine, tetraphenylphosphonium tetraphenylborate salt or 2-methylimidazole A curing accelerator and (D) an inorganic filler selected from spherical fused silica, crystalline silica, secondary agglomerated silica or aluminum hydroxide are essential components, and the inorganic filler is 87 to 94% by weight in the total epoxy resin composition. An epoxy resin composition for semiconductor encapsulation, characterized in that
[0006]
[Chemical 1]
[Chemical 2]
(N is an average value and an integer of 1 to 7)
[0009]
[3] A semiconductor device comprising a semiconductor element sealed using the epoxy resin composition according to the item [1] ,
It is.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The crystalline epoxy resin containing the epoxy resin represented by the formula (1) used in the present invention is a bifunctional epoxy resin having two epoxy groups in one molecule, and compared with a conventional crystalline biphenyl type epoxy resin. Because of its low steric hindrance and quick reaction with the phenolic resin, which is a curing agent, and high curability, it has excellent moldability. Usually, bisphenol A type epoxy resins do not have a melting point because the molecular weight distribution is broad, and have different softening points depending on the number average molecular weight difference. That is, a resin having a small average molecular weight (a number average molecular weight of 700 or less) is low in viscosity but is liquid at room temperature. Therefore, the handling workability is poor, and the obtained epoxy resin composition is easily solidified. A resin having a large molecular weight (number average molecular weight of 900 or more) is solid at room temperature but has high viscosity, and an epoxy resin composition using the resin cannot provide sufficient fluidity. The crystalline epoxy resin containing the epoxy resin represented by the formula (1) used in the present invention has a substantially single molecular weight, and its melting point is preferably 40 to 50 ° C. from the viewpoint of handling workability. If the melting point is within this range, it is solid at room temperature, easy to handle, and in the melted state, it has a low melt viscosity, which is a characteristic of crystalline epoxy resin, and has excellent fluidity. It can mix | blend, the low moisture absorption and low thermal expansion of the hardened | cured material of an epoxy resin composition are achieved, and solder resistance can be improved. These epoxy resins are commercially available as YL6810 from Japan Epoxy Resin Co., Ltd. The melt viscosity of YL6810 at 150 ° C. is 0.1 poise or less. On the other hand, the melt viscosity at 150 ° C. of the crystalline biphenyl type epoxy resin YX4000H (Japan Epoxy Resin Co., Ltd.) is 0.2 poise.
The melting point of the epoxy resin in the present invention refers to the endothermic peak measured with a differential scanning calorimeter (Seiko Denshi Kogyo Co., Ltd.) using about 10 mg of epoxy resin and measured at a heating rate of 5 ° C./min. Say temperature.
[0011]
In the range which does not impair the characteristic of the crystalline epoxy resin containing the epoxy resin shown by Formula (1), it can use together with another epoxy resin. Examples of the epoxy resins that can be used in combination include phenol novolac type epoxy resins, cresol novolac type epoxy resins, phenol aralkyl (including phenylene skeleton and diphenylene skeleton) type epoxy resins, biphenyl type epoxy resins, dicyclopentadiene modified phenol type epoxy resins, Phenolmethane type epoxy resin, naphthalene ring-containing epoxy resin, hydroquinone type epoxy resin and the like may be mentioned, and these may be used alone or in combination.
[0012]
The phenol resin used in the present invention refers to monomers, oligomers, and polymers in general having two or more phenolic hydroxyl groups in one molecule, and the molecular weight and molecular structure thereof are not limited. For example, phenol novolak resin, cresol novolak Resin, dicyclopentadiene-modified phenol resin, terpene-modified phenol resin, phenol resin represented by general formula (2), phenol resin represented by general formula (3), and the like, and epoxy resin represented by formula (1) In order to maximize the characteristics of the crystalline epoxy resin contained, since the water absorption of the cured product is small because the number of hydroxyl groups in the molecule is small and the viscosity can be lowered, it is particularly shown by the general formula (2). The phenol resin represented by the general formula (3) is preferred.
A in the phenol resin represented by the general formula (2) or the general formula (3) is an aromatic compound having one or two hydroxyl groups in a substituted or unsubstituted aromatic hydrocarbon. Includes phenol, cresols, resorcin, catechol, naphthol, dinaphthol and the like, and phenol and naphthol are preferable from the viewpoint of curability and water absorption.
[0013]
The curing accelerator used in the present invention may be any accelerator that promotes the crosslinking reaction between the epoxy resin and the phenol resin. For example, amidine compounds such as 1,8-diazabicyclo (5,4,0) undecene-7. Organic phosphorus compounds such as triphenylphosphine and tetraphenylphosphonium / tetraphenylborate salts, and imidazole compounds such as 2-methylimidazole, but are not limited thereto. These curing accelerators may be used alone or in combination.
[0014]
There is no restriction | limiting in particular about the inorganic filler used by this invention, The thing generally used for the sealing material can be used. Examples thereof include fused crushed silica, fused spherical silica, crystalline silica, secondary agglomerated silica, alumina, titanium white, aluminum hydroxide, and the like, and fused spherical silica is particularly preferable. As the shape of the spherical silica, it is preferable that the shape is spherical as much as possible in order to improve fluidity, and the particle size distribution is broad.
[0015]
It is essential that the content of the inorganic filler is 87 to 94% by weight in the total epoxy resin composition. If it is less than 87% by weight, the epoxy resin composition solidifies and the handling workability deteriorates, and the low hygroscopicity of the cured product of the epoxy resin composition cannot be obtained, resulting in insufficient solder resistance of the semiconductor device. If it exceeds wt%, the fluidity of the epoxy resin composition is lowered, resulting in poor filling during molding, and inconveniences such as deformation of gold wires in the semiconductor device due to increased viscosity.
Further, if necessary, the inorganic filler may be used after being pretreated with a coupling agent, epoxy resin, phenol resin or the like. As a treatment method, for example, a method of removing the solvent after mixing with a solvent or a direct method may be used. There is a method of adding to an inorganic filler and processing using a mixer.
[0016]
In addition to the components (A) to (D), the epoxy resin composition of the present invention includes a brominated epoxy resin, an antimony oxide, a flame retardant such as a phosphorus compound, and an inorganic ion exchanger such as a bismuth oxide hydrate. , Coupling agents such as γ-glycidoxypropyltrimethoxysilane, colorants such as carbon black and bengara, low stress components such as silicone oil and silicone rubber, natural waxes, synthetic waxes, higher fatty acids and their metal salts or Various additives such as a release agent such as paraffin and an antioxidant may be appropriately blended.
In the epoxy resin composition of the present invention, the components (A) to (D) and other additives are mixed at room temperature using a mixer, melt-kneaded in a kneader such as a roll, kneader or extruder, and pulverized after cooling. Is obtained.
In order to seal an electronic component such as a semiconductor element and manufacture a semiconductor device using the epoxy resin composition of the present invention, it may be cured by a molding method such as a transfer mold, a compression mold, or an injection mold.
[0017]
【Example】
Hereinafter, the present invention will be described in detail with reference to Production Examples, Examples, and Comparative Examples, but the present invention is not limited to these Examples.
The melting point of the crystalline epoxy resin was measured by the above method.
The abbreviations and structures of epoxy resins and phenol resins used in Examples and Comparative Examples are collectively shown below.
[0018]
Epoxy resin (1): Resin mainly composed of epoxy resin represented by formula (4) (manufactured by Japan Epoxy Resin Co., Ltd., YL6810) (melting point: 45 ° C., epoxy equivalent: 172 g / eq)
[0019]
[Chemical formula 5]
[0020]
Epoxy resin (2): Resin mainly composed of epoxy resin represented by formula (5) (manufactured by Japan Epoxy Resin Co., Ltd., YX4000K) (melting point 105 ° C., epoxy equivalent: 185 g / eq)
[0021]
[Chemical 6]
[0022]
Phenol resin (1): Phenol resin represented by formula (6) (softening point 70 ° C., hydroxyl group equivalent 170 g / eq)
[0023]
[Chemical 7]
[0024]
Phenol resin (2): Phenol resin represented by formula (7) (softening point 87 ° C., hydroxyl group equivalent 210 g / eq)
[0025]
[Chemical 8]
[0026]
Phenol resin (3): Phenol resin represented by formula (8) (softening point 67 ° C., hydroxyl group equivalent 203 g / eq)
[0027]
[Chemical 9]
[0028]
The blending ratio of the production examples of the epoxy resin composition is parts by weight.
Reference example 1
Epoxy resin (1) 5.51 parts by weight Phenolic resin (1) 5.44 parts by weight Triphenylphosphine 0.15 parts by weight Fused spherical silica (average particle size 15 μm) 88.00 parts by weight γ-glycidoxypropyltrimethoxy Silane 0.30 parts by weight Carbon black 0.30 parts by weight Carnauba wax 0.30 parts by weight are mixed at room temperature using a mixer, kneaded at 70 to 120 ° C. using two rolls, cooled and pulverized. An epoxy resin composition was obtained. The obtained epoxy resin composition was evaluated by the following methods. The results are shown in Table 1.
[0029]
Spiral flow: Using a mold for spiral flow measurement according to EMMI-1-66, measurement was performed at a mold temperature of 175 ° C., an injection pressure of 6.9 MPa, and a curing time of 2 minutes. The unit is cm.
Curing torque: Using a curast meter (manufactured by Orientec Co., Ltd., JSR curast meter IVPS type), the mold temperature was 175 ° C., and the torque 90 seconds after the start of heating was determined. The torque in the curast meter is a parameter of curability, and the larger the value, the better the curability. The unit is N · m.
Moisture absorption: Using a transfer molding machine, a disk with a mold temperature of 175 ° C., an injection pressure of 9.8 MPa, a curing time of 2 minutes was formed into a disk with a diameter of 50 mm and a thickness of 3 mm, and post-cured at 175 ° C. for 8 hours. The sample was allowed to stand for 168 hours in an environment of 85 ° C. and a relative humidity of 60%, and the weight change was measured to obtain the moisture absorption rate. The unit is% by weight.
Solder resistance: Using a transfer molding machine, 144 pQFP (20 × 20 × 1.7 mm thickness) was molded at a mold temperature of 175 ° C., an injection pressure of 9.8 MPa, and a curing time of 2 minutes, and at 175 ° C. for 8 hours. It was post-cured and left in an environment of 85 ° C., relative humidity 65% and 85 ° C., relative humidity 85% for 168 hours, respectively, and IR reflow treatment (240 ° C.) was performed. The presence or absence of internal peeling and cracks after the treatment was observed with an ultrasonic flaw detector, and the number of defective packages was counted. When the number of defective packages is n, n / 10 is displayed.
Mold releasability: Using a transfer molding machine, 144 pQFP (20 × 20 × 1.7 mm thickness) was continuously molded 10 times with a mold temperature of 175 ° C., an injection pressure of 9.8 MPa, and a curing time of 2 minutes. In this 10 times molding, it was judged as “Good” if it adhered to the mold at the time of mold release or cracked or chipped in the molded product.
Mold dirt: Using a transfer molding machine, 144 pQFP (20 × 20 × 1.7 mm thickness) was continuously molded 500 times at a mold temperature of 175 ° C., an injection pressure of 9.8 MPa, and a curing time of 2 minutes. The case where both the surface of the molded product and the mold surface were whitened was judged as x, the case where any of them was whitened as Δ, and the case where none of them was whitened as ○.
[0030]
Example 2 , Reference Examples 3-6, Comparative Examples 1-8
Table 1, according to the formulation of Table 2, similarly to obtain an epoxy resin composition as in Reference Example 1, was evaluated in the same manner as in Reference Example 1. The results are shown in Tables 1 and 2.
The hydroxyl group equivalent of the phenol novolac resin used in Reference Example 4 and Comparative Example 4 is 104 g / eq. The softening point of the solid bisphenol A type epoxy resin used in Comparative Example 8 is 64 ° C., and the epoxy equivalent is 470 g / eq.
[0031]
[Table 1]
[0032]
[Table 2]
[0033]
【The invention's effect】
According to the present invention, an epoxy resin composition having a property of fast curing, less mold contamination, excellent moldability, and excellent low moisture absorption and low thermal expansion is obtained, which is used to seal a semiconductor element. The resulting semiconductor device has excellent solder resistance.

Claims (2)

(A) A crystalline epoxy resin represented by formula (1) having a melting point of 40 to 50 ° C. obtained by measuring at a heating rate of 5 ° C./min using a differential scanning calorimeter, (B) in formula (7) A phenolic resin represented by (C) 1,8-diazabicyclo (5,4,0) undecene-7, triphenylphosphine, tetraphenylphosphonium tetraphenylborate salt or 2-methylimidazole And (D) an inorganic filler selected from spherical fused silica, crystalline silica, secondary agglomerated silica or aluminum hydroxide is an essential component, and the inorganic filler is 87 to 94% by weight in the total epoxy resin composition. An epoxy resin composition for semiconductor encapsulation.
(N is an average value and an integer of 1 to 7)   A semiconductor device comprising a semiconductor element sealed with the epoxy resin composition according to claim 1.