JP2003192877A - Epoxy resin composition for sealing semiconductor and semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an epoxy resin composition free from a bromine-containing organic compound and an antimony compound, having excellent adhesion to a substrate, flame retardancy and resistance to solder stress. <P>SOLUTION: This epoxy resin composition for sealing a semiconductor comprises (A) an epoxy resin represented by general formula (1), (B) a phenol resin represented by general formula (2), (C) an inorganic filler, (D) a curing accelerator and (E) an N-cyclohexyl-2-benzothiazolylsulfamide as essential components, and the content of the whole inorganic materials in the whole epoxy resin composition is 84-94 wt.%. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an epoxy resin composition for semiconductor encapsulation and a semiconductor device using the same.

[0002]

2. Description of the Related Art Conventionally, semiconductor devices such as diodes, transistors, and integrated circuits are mainly sealed with an epoxy resin composition. In order to impart flame retardancy to these epoxy resin compositions. Usually, a bromine-containing organic compound and an antimony compound such as antimony trioxide and antimony tetraoxide are mixed. However, from the viewpoint of environment and hygiene, it is desired to develop an epoxy resin composition having excellent flame retardancy without using a bromine-containing organic compound and an antimony compound. Also, when mounting a semiconductor device on a printed circuit board, solder containing lead (tin-lead alloy) is used. Similarly, from the viewpoint of environment and hygiene, solder containing lead (tin-lead alloy). It is desired not to use. The melting point of solder containing lead (tin-lead alloy) is 183 ° C, and the temperature of the soldering process during mounting is 220 to 240 ° C. On the other hand, a lead-free solder typified by a tin-silver alloy has a high melting point and the temperature at the time of soldering is about 260 ° C., and therefore an epoxy resin composition having excellent solder stress resistance in a higher temperature range. Development of things is desired. In addition, in the recent market trend of miniaturization, weight reduction, and high functionality of electronic devices, the high integration of semiconductor elements has been advanced year by year, and the surface mounting of semiconductor devices has been promoted. Semiconductor devices have been developed and are starting to shift from semiconductor devices having conventional structures.

An area mounting type semiconductor device is a ball grid array (hereinafter referred to as BGA), or a chip size package (hereinafter referred to as CSP) in pursuit of further miniaturization.
, Etc. are typical, but these are conventional QFP,
This is developed to meet the demand for higher pin count and higher speed, which is approaching the limit of surface mount semiconductor devices represented by SOP. As a structure, a hard circuit board typified by a bismaleimide triazine resin (hereinafter referred to as BT resin) / copper foil circuit board, or a flexible circuit board typified by a polyimide resin film / copper foil circuit board is provided on one side. A semiconductor element is mounted, and the semiconductor element mounting surface, that is, only one surface of the substrate is molded and sealed with an epoxy resin composition or the like. Further, it is characterized in that solder balls are formed two-dimensionally in parallel on the surface opposite to the semiconductor element mounting surface of the substrate and are joined to the substrate on which the semiconductor device is mounted. Furthermore, as a substrate on which a semiconductor element is mounted, a structure using a metal substrate such as a lead frame has been devised in addition to the above organic substrate.

When soldering these area-mounted semiconductor devices by means of infrared reflow, vapor phase soldering, solder dipping, etc., they exist inside the semiconductor device due to moisture absorption from the cured product of the epoxy resin composition and the organic substrate. Cracks may occur in the semiconductor device due to stress caused by rapid evaporation of water at high temperature, or peeling may occur at the interface between the semiconductor element mounting surface of the substrate and the cured product of the epoxy resin composition. High strength, low stress, low moisture absorption, and high adhesion to the substrate are required. Conventional B
For area mounting type semiconductor devices such as GA and CSP, a triphenol methane type epoxy resin and an epoxy resin composition containing a triphenol methane type phenol resin as a resin component have been used. This epoxy resin composition has a high Tg, excellent curability, and excellent bending strength when heated, but has a high moisture absorption rate of the cured product, and a relatively high melt viscosity of the epoxy resin composition. There is a limit to the high filling of the inorganic filler, the low moisture absorption is insufficient, and there is a problem in the solder stress resistance. Therefore, the adhesion to the substrate is high, the flame resistance,
Development of an epoxy resin composition having excellent solder stress resistance is desired.

[0005]

DISCLOSURE OF THE INVENTION The present invention is an epoxy resin composition for semiconductor encapsulation which does not contain a bromine-containing organic compound and an antimony compound and is excellent in adhesion to a substrate, flame retardancy, and solder stress resistance. And a semiconductor device using the same.

[0006]

The present invention provides [1] (A)
An epoxy resin represented by the general formula (1), (B) a phenol resin represented by the general formula (2), (C) an inorganic filler,
(D) Curing accelerator, and (E) N-cyclohexyl-2
-Benzothiazolylsulfanamide as an essential component,
84% by weight or more of all inorganic substances in the total epoxy resin composition,
94% by weight or less, an epoxy resin composition for semiconductor encapsulation,

[0007]

[Chemical 5] (R1 and R2 are alkyl groups having 1 to 4 carbon atoms and may be the same or different. A is an integer of 0 to 3 and b is 0.
An integer of ~ 4. n is an average value and is a positive number from 1 to 5)

[0008]

[Chemical 6] (R1 and R2 are alkyl groups having 1 to 4 carbon atoms and may be the same or different. A is an integer of 0 to 3 and b is 0.
An integer of ~ 4. n is an average value and is a positive number from 1 to 5)

[2] The epoxy resin represented by the general formula (1) is the epoxy resin represented by the formula (3): [1]
The epoxy resin composition for semiconductor encapsulation according to the item,

[0010]

[Chemical 7] (N is an average value and is a positive number from 1 to 5)

[3] The epoxy resin composition for semiconductor encapsulation according to the item [1] or [2], wherein the phenol resin represented by the general formula (2) is a phenol resin represented by the formula (4).

[0012]

[Chemical 8] (N is an average value and is a positive number from 1 to 5)

[4] N-cyclohexyl-2-benzothiazolyl sulfanamide [1], [2] or 0.01% by weight or more and 0.1% by weight or less in the total epoxy resin composition. A semiconductor element is encapsulated using the epoxy resin composition for semiconductor encapsulation according to the item [3] and the epoxy resin composition for semiconductor encapsulation according to any one of the items [1] to [4]. A semiconductor device characterized by the following.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION General formula (1) used in the present invention
The epoxy resin represented by has a hydrophobic and rigid biphenyl skeleton between epoxy groups, and a cured product of an epoxy resin composition using this has a low moisture absorption rate and a glass transition temperature (hereinafter, referred to as Tg). It has a low elastic modulus in a high temperature range exceeding 100 ° C. and is excellent in adhesiveness to semiconductor elements, organic substrates, and metal substrates. Further, it has a feature that it has high heat resistance despite its low crosslink density. Therefore, the semiconductor device sealed with the resin composition using this epoxy resin has excellent resistance to solder stress. N in the general formula (1) is an average value and is a positive number of 1 to 5, preferably 1 to 3. When n is less than the lower limit value, the curability of the epoxy resin composition decreases. When n exceeds the upper limit value, the viscosity becomes high and the fluidity of the epoxy resin composition decreases. The epoxy resin represented by the general formula (1) is 1
One type may be used alone, or two or more types may be used in combination. Among the epoxy resins represented by the general formula (1), the formula (3)
The epoxy resin represented by is particularly preferable.

Other epoxy resins may be used in combination as long as the original characteristics of the epoxy resin represented by the general formula (1) are not impaired. When used in combination, it is desirable to use monomers, oligomers, and polymers having an epoxy group in the molecule as low as possible, such as phenol novolac type epoxy resin, cresol novolac type epoxy resin, and biphenyl type epoxy resin. , Bisphenol type epoxy resin, stilbene type epoxy resin, triphenol methane type epoxy resin, phenol aralkyl type epoxy resin (having a phenylene skeleton), naphthol type epoxy resin, naphthalene type epoxy resin, alkyl modified triphenol methane type epoxy resin, triazine Examples thereof include a nucleus-containing epoxy resin and a dicyclopentadiene-modified phenol type epoxy resin. These may be used alone or in combination of two or more. By adjusting the amount of the epoxy resin represented by the general formula (1) to be used, solder stress resistance can be maximized. In order to bring out the effect of resistance to soldering stress, it is preferable to contain the epoxy resin represented by the general formula (1) in an amount of 30% by weight or more, based on the total amount of the epoxy resin.
It is preferably 0% by weight or more. Below the lower limit, the solder stress resistance may become insufficient.

The phenol resin represented by the general formula (2) used in the present invention has a hydrophobic and rigid biphenyl skeleton between phenolic hydroxyl groups, and a cured product of an epoxy resin composition using this is It has a low hygroscopicity, a low elastic modulus in a high temperature range exceeding Tg, and excellent adhesiveness to semiconductor elements, organic substrates, and metal substrates. Further, it has a feature that it has high heat resistance despite its low crosslink density. Therefore, the semiconductor device sealed with the resin composition using this phenol resin has excellent resistance to solder stress. In the general formula (2), n is an average value and is a positive number of 1 to 5, preferably 1 to 3. n
Is less than the lower limit value, the curability of the epoxy resin composition decreases, which is not preferable. When n exceeds the upper limit value, the viscosity becomes high and the fluidity of the epoxy resin composition decreases. The phenol resin represented by the general formula (2) may be used alone or in combination of two or more kinds. Among the phenol resins represented by the general formula (2), the phenol resin represented by the formula (4) is particularly preferable.

Other phenol resins may be used in combination as long as the characteristics of the phenol resin represented by the general formula (2) used in the present invention are not impaired. When used in combination, it is desirable to use a monomer, an oligomer, or a polymer having a phenolic hydroxyl group in the molecule, which has a viscosity as low as possible. ), Naphthol aralkyl resin, triphenol methane resin, terpene modified phenol resin, dicyclopentadiene modified phenol resin, and the like,
These may be used alone or in combination of two or more. By adjusting the amount of the phenol resin represented by the general formula (2) to be used, solder stress resistance can be maximized. In order to bring out the effect of resistance to soldering stress, the phenol resin represented by the general formula (2) is preferably contained in an amount of 30% by weight or more, and particularly preferably 50% by weight or more, in the total phenol resin. Thirty
If it is less than weight%, the solder stress resistance may be insufficient. The equivalent ratio of the epoxy groups of all epoxy resins to the phenolic hydroxyl groups of all phenol resins is preferably 0.5 to 2, and more preferably 0.7 to 1.5. When it is out of the range of 0.5 to 2, moisture resistance, curability and the like may be deteriorated.

The type of the inorganic filler used in the present invention is not particularly limited, but examples thereof include fused crushed silica, fused spherical silica, crystalline silica, secondary agglomerated silica, alumina, titanium white and aluminum hydroxide. Fused spherical silica is particularly preferable. The shape of the fused spherical silica is preferably infinitely spherical in order to improve fluidity, and the particle size distribution is broad.

The total content of inorganic substances including the inorganic filler, the flame retardant such as metal hydroxide added as necessary, and the resistance to inorganic ion exchange is 84 in the total epoxy resin composition.
The amount is not less than 94% by weight and not less than 94% by weight. If the amount is less than the lower limit, the cured product of the epoxy resin composition may not have low hygroscopicity, resulting in insufficient solder stress resistance or insufficient flame retardancy. Further, if the upper limit is exceeded, the fluidity of the epoxy resin composition will decrease, and filling failure or the like will occur during molding,
The increase in viscosity may cause inconvenience such as deformation of the gold wire in the semiconductor device.

The present invention achieves flame retardancy without the use of bromine-containing organic compounds and antimony compounds. The bromine atom and the antimony atom in the total epoxy resin composition in the present invention are each 0.05% by weight or less. This means that, for economic reasons, bromine atom and antimony atom are not added other than the raw material and a trace amount of components mixed in the production stage. The inorganic filler used in the present invention is preferably sufficiently mixed in advance. If necessary, the inorganic filler may be pretreated with a coupling agent, an epoxy resin or a phenol resin, and the treatment may be carried out by mixing with a solvent and then removing the solvent or by direct inorganic filling. There is a method of adding it to a material and mixing it with a mixer.

The curing accelerator used in the present invention includes:
There is no particular limitation as long as it promotes the reaction between the epoxy group and the phenolic hydroxyl group, and examples thereof include diazabicycloalkenes such as 1,8-diazabicyclo (5,4,0) undecene-7 and derivatives thereof, tributylamine, Amine compounds such as benzyldimethylamine, imidazole compounds such as 2-methylimidazole, organic phosphines such as triphenylphosphine and methyldiphenylphosphine, tetraphenylphosphonium / tetraphenylborate, tetraphenylphosphonium / tetrabenzoic acid borate, tetraphenyl Phosphonium tetranaphthoic acid borate, tetraphenylphosphonium
Examples thereof include tetra-substituted phosphonium / tetra-substituted borate such as tetranaphthoyloxyborate and tetraphenylphosphonium / tetranaphthyloxyborate. These may be used alone or in combination of two or more.

N-cyclohexyl-used in the present invention
2-Benzothiazolylsulfanamide is a cured product of an epoxy resin composition using the same, a hard circuit board represented by BT resin / copper foil circuit board, and a flexible resin represented by polyimide resin film / copper foil circuit board. It is effective in improving the affinity at the interface with a circuit board or a metal substrate such as a lead frame or improving the adhesiveness at the interface by forming a chemical bond. It also has flame retardancy. Furthermore, from the viewpoint of long-term reliability of the semiconductor device, chlorine ions contained as impurities,
It is desirable that the amount of sodium ions, sulfate ions, and other free ions be as small as possible. The compounding amount of N-cyclohexyl-2-benzothiazolyl sulfanamide is 0.01% by weight or more in the total epoxy resin composition,
It is preferably 0.1% by weight or less. If it is less than the lower limit, flame retardancy and solder stress resistance become insufficient, which is not preferable. If the upper limit is exceeded, the curability of the resin composition will decrease,
Solder stress resistance becomes insufficient, which is not preferable.

The epoxy resin composition of the present invention comprises (A)-
In addition to the component (E), if necessary, a coupling agent such as γ-glycidoxypropyltrimethoxysilane, a coloring agent such as carbon black and red iron oxide, a stress reducing component such as silicone oil and silicone rubber, a natural wax, Various additives such as a synthetic wax, a higher fatty acid and a metal salt thereof, a releasing agent such as paraffin, and an antioxidant may be appropriately mixed. The epoxy resin composition of the present invention,
The components (A) to (E), other additives, and the like are mixed at room temperature using a mixer, melt-kneaded with a kneader such as a roll, kneader, or extruder, cooled, and pulverized. In order to manufacture a semiconductor device by sealing an electronic component such as a semiconductor element using the epoxy resin composition of the present invention, it may be cured and molded by a molding method such as a transfer mold, a compression mold, an injection mold.

[0024]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The mixing ratio is parts by weight. Example 1 Epoxy resin represented by formula (3) (softening point 60 ° C., epoxy equivalent 275) 7.30 parts by weight Phenolic resin represented by formula (4) (softening point 65 ° C., hydroxyl equivalent 200) 5.40 parts by weight Parts fused spherical silica (average particle size 30 μm) 85.50 parts by weight bismuth oxide hydrate 0.40 parts by weight tetraphenylphosphonium tetrakis (1-naphthoyloxy) borate 0.45 parts by weight N-cyclohexyl-2-benzo Thiazolylsulfanamide 0.05 part by weight γ-glycidoxypropyltrimethoxysilane 0.30 part by weight Carbon black 0.30 part by weight Carnauba wax 0.30 part by weight using a mixer at room temperature to give 70- 2 at 120 ° C
The mixture was kneaded using a shaft roll, cooled, and then pulverized to obtain an epoxy resin composition. The obtained epoxy resin composition was evaluated by the following methods. The results are shown in Table 1.

Evaluation method Spiral flow: Using a mold for spiral flow measurement according to EMMI-1-66, the mold temperature was 175 ° C., the injection pressure was 6.9 MPa, and the curing time was 120 seconds. The unit is cm. Torque ratio: Curast meter (Orientec Co., Ltd.)
Manufactured by JSR Curastometer IVPS type), the mold temperature is 175 ° C., the torque is calculated 90 seconds after the start of heating and 300 seconds after the start of heating. Torque ratio: (torque after 90 seconds) / (300
The torque in seconds) was calculated. The torque in the curast meter is a parameter of thermal rigidity, and the larger the torque ratio, the better the curability. Moisture absorption rate: Using a transfer molding machine, mold temperature 17
A molded product having a diameter of 50 mm and a thickness of 3 mm was molded at 5 ° C., an injection pressure of 9.8 MPa, and a curing time of 120 seconds, and post-cured at 175 ° C. for 8 hours, and the resulting molded product was heated at 30 ° C. and a relative humidity. Leave it in a 60% environment for 696 hours,
The change in weight was measured to determine the moisture absorption rate. Units%.

Flame retardance: Using a transfer molding machine,
Mold temperature 175 ° C, injection pressure 9.8 MPa, curing time 1
Length of 127 mm, width of 12.7 mm, thickness of 1.6 in 20 seconds
After molding a molded product of mm in size and post-curing it at 175 ° C for 8 hours, leave the resulting molded product in an environment of 23 ° C and a relative humidity of 50% for 48 hours to make it flame-retardant according to UL-94. A sex test was conducted. Adhesion: 42 alloy frame, 42 alloy frame surface coated with polymethylmethacrylate solder resist (hereinafter referred to as PMMA), or 42 alloy frame surface plated with Ag (hereinafter referred to as Ag plated) Then, a test piece of 2 mm x 2 mm x 2 mm was placed on a mold temperature 175 using a transfer molding machine.
C., injection pressure 9.8 MPa, curing time 120 seconds, and post-cure at 175.degree. C. for 8 hours.
After treating for 696 hours in an environment of 30 ° C. and 60% relative humidity, IR reflow treatment (260 ° C.) was performed. The shear strength between the cured product of the epoxy resin composition and the frame was measured using an automatic shear strength measuring device (PC2400 manufactured by DAGE Co.). The unit is N / mm ² .

Solder stress resistance: Using a transfer molding machine, mold temperature 175 ° C., injection pressure 9.8 MPa,
225 pBGA with a curing time of 120 seconds (substrate has a thickness of 0.3
6 mm BT resin / glass cloth substrate, package size 24 mm x 24 mm, thickness 1.17 mm, silicon chip size 9 mm x 9 mm, thickness 0.35 mm, 25 μm diameter gold wire between chip and bonding pad of circuit board Are bonded together). Eight packages that were treated for 8 hours at 175 ° C as post cure,
After treating for 696 hours in an environment of 30 ° C. and 60% relative humidity, IR reflow treatment (260 ° C.) was performed. The presence or absence of internal peeling or 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, it is displayed as n / 8. Bromine atom,
Antimony atom content: 40m diameter at a pressure of 5.9MPa
m, and the thickness was 5 to 7 mm, and the obtained molded product was quantified for the content of bromine atom and antimony atom in the total epoxy resin composition using a fluorescent X-ray analyzer. The unit is% by weight.

Examples 2 to 5 and Comparative Examples 1 to 6 According to the formulations shown in Table 1, epoxy resin compositions were obtained in the same manner as in Example 1 and evaluated in the same manner as in Example 1. The results are shown in Table 1. In Example 4, a biphenyl type epoxy resin (YX4000H manufactured by Japan Epoxy Resin Co., Ltd.,
A melting point of 105 ° C. and an epoxy equivalent of 197) were used. In Example 5, the curing accelerator of formula (5) was used.

[0029]

[Chemical 9]

In Example 4 and Comparative Examples 5 and 6, a phenol aralkyl resin (XL-225 manufactured by Mitsui Chemicals, Inc., softening point 75 ° C., hydroxyl equivalent 174) was used.

[0031]

[Table 1]

[0032]

According to the present invention, a bromine-containing organic compound,
An epoxy resin composition having good adhesion to a substrate and flame retardancy can be obtained without containing an antimony compound, and a semiconductor device using the same has excellent solder stress resistance.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 23/29 H01L 23/30 R 23/31 F term (reference) 4J002 CD031 CD041 CD051 CD061 CD071 CD141 CD181 CE002 DE096 DE136 DE146 DJ016 EN047 EU137 EV328 EW017 EW177 FA086 FD016 FD090 FD130 FD138 FD142 FD157 FD160 FD200 FD348 GQ05 4J036 AA02 AA04 AC01 AC02 AC03 AC05 AC18 AD07 AD08 FB05 FA07 FB05 FA07 DC13 FA02 DC03 FA04 DC03 FA02 DC03 FA04 DC03 FA02 DC04 FA03 FA07 DC07 FA02 DC03 FA02 KA05 4M109 EA02 EB03 EB04 EB12 EC05

Claims (5)

[Claims] 1. An epoxy resin represented by the general formula (1) (A), a phenol resin represented by the general formula (2) (B),
(C) Inorganic filler, (D) Curing accelerator, and (E) N-
An epoxy resin composition for semiconductor encapsulation, comprising cyclohexyl-2-benzothiazolyl sulfanamide as an essential component, and the total inorganic content of the total epoxy resin composition is 84% by weight or more and 94% by weight or less. [Chemical 1] (R1 and R2 are alkyl groups having 1 to 4 carbon atoms and may be the same or different. A is an integer of 0 to 3 and b is 0.
An integer of ~ 4. n is an average value and is a positive number from 1 to 5) (R1 and R2 are alkyl groups having 1 to 4 carbon atoms and may be the same or different. A is an integer of 0 to 3 and b is 0.
An integer of ~ 4. n is an average value and is a positive number from 1 to 5) 2. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the epoxy resin represented by the general formula (1) is an epoxy resin represented by the formula (3). [Chemical 3] (N is an average value and is a positive number from 1 to 5) 3. The phenol resin represented by the general formula (2) is a phenol resin represented by the formula (4).
Or the epoxy resin composition for semiconductor encapsulation according to 2. [Chemical 4] (N is an average value and is a positive number from 1 to 5) 4. N-cyclohexyl-2-benzothiazolylsulfanamide is added to the total epoxy resin composition in an amount of 0.
The content is 01% by weight or more and 0.1% by weight or less.
Or the epoxy resin composition for semiconductor encapsulation according to 3. 5. A semiconductor device, comprising a semiconductor element encapsulated with the epoxy resin composition for semiconductor encapsulation according to any one of claims 1 to 4.