JP2003082195A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an epoxy resin composition for semiconductor-sealing free from a halogen-containing flame-retardant and an antimony compound and excellent in molding properties, flame retardancy and solder reflow resistance reliability. SOLUTION: The epoxy resin composition for semiconductor-sealing comprises as essential ingredients (A) a dicyclopentadiene type epoxy resin, (B) a phenolic resin, (C) a curing accelerator, (D) an inorganic filler and (E) a cyclic phosphazene compound.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an epoxy resin composition for semiconductor encapsulation, which does not contain a halogen-based flame retardant or an antimony compound and is excellent in flame retardancy, high temperature storage characteristics and solder reflow resistance, and a semiconductor device. It is about.

[0002]

2. Description of the Related Art Conventionally, electronic parts such as diodes, transistors and integrated circuits are mainly sealed with an epoxy resin composition. In order to impart flame retardancy, these epoxy resin compositions usually contain a bromine atom-containing flame retardant and antimony compounds such as antimony trioxide, antimony tetroxide and antimony pentoxide. However, with increasing awareness of environmental protection worldwide, there is an increasing demand for an epoxy resin composition having flame retardancy without using a halogen-based flame retardant or an antimony compound. Further, when a semiconductor device sealed with an epoxy resin composition containing a halogen-based flame retardant and an antimony compound is stored at high temperature, a thermally decomposed halide is liberated from these flame retardant components, and a joint portion of a semiconductor element is released. Epoxy resin that can achieve V-0 of UL-94 flame retardancy without using halogen-based flame retardants and antimony compounds as flame retardants. A composition is required. As described above, the corrosion resistance of the joint portion (bonding pad portion) of the semiconductor element after the semiconductor device is stored at a high temperature (for example, 185 ° C.) is referred to as a high temperature storage characteristic, and the high temperature storage characteristic is improved. As a method to do so, a method using diantimony pentoxide (JP-A-55-146950) or a method combining antimony oxide and an organic phosphine (JP-A-6-61).
1-53321) and the like, and their effects have been confirmed, but some epoxy resin compositions are unsatisfactory with respect to the recent high required level of high-temperature storage characteristics for semiconductor devices. Then, Japanese Patent Laid-Open No. 10-259
By using a cyclic phosphazene compound as proposed in Japanese Patent No. 292, it was possible to achieve sufficient flame retardancy without using a bromine compound and an antimony compound, but with conventional formulations, an increase in moisture absorption rate was achieved. However, there has been a problem that the solder reflow reliability is lowered due to a decrease in strength, an increase in moisture absorption rate, and the like. Therefore, there is a demand for an epoxy resin composition that can obtain good moldability and reliability even if the amount of the cyclic phosphazene compound added is reduced.

Further, a dicyclopentadiene type epoxy resin is used as a part of the sealing material in order to improve the reliability of the solder reflow resistance. Due to its high glass transition point, low elastic modulus and low moisture absorption, it has good solder reflow reliability, but it is inferior in flame resistance. It is necessary to add a large amount of flame retardant. Therefore, sufficient moldability and high temperature storage characteristics could not be exhibited. That is, maintaining flame retardancy,
There is a demand for an epoxy resin composition which is excellent in moldability and solder reflow reliability and which does not use a halogen-based flame retardant or an antimony compound.

[0004]

DISCLOSURE OF THE INVENTION The present invention does not contain a halogen-based flame retardant and an antimony compound, and has moldability, flame retardancy,
The present invention provides an epoxy resin composition for semiconductor encapsulation having excellent solder reflow resistance and a semiconductor device in which a semiconductor element is encapsulated using the same.

[0005]

The present invention provides [1] (A) dicyclopentadiene type epoxy resin,
An epoxy resin composition for semiconductor encapsulation, which comprises (B) a phenol resin, (C) a curing accelerator, (D) an inorganic filler, and (E) a cyclic phosphazene compound as essential components. [2] The epoxy resin composition for semiconductor encapsulation according to the item [1], wherein the cyclic phosphazene compound is a cyclic phosphazene compound represented by the general formula (1).

[Chemical 2] (In the formula, n represents an integer of 3 to 7 and R represents the same or different organic groups.) [3] Of the 2n Rs of the cyclic phosphazene compound represented by the general formula (1), at least n is The epoxy resin composition for semiconductor encapsulation according to the item [2], which is a phenoxy group. [4] The epoxy resin for semiconductor encapsulation according to any one of the items [1] to [3], wherein the bromine atom and the antimony atom contained in the total epoxy resin composition are each less than 0.1% by weight. Composition. [5] A semiconductor device obtained by encapsulating a semiconductor element using the epoxy resin composition for encapsulating a semiconductor according to any one of items [1] to [4]. Is.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The dicyclopentadiene type epoxy resin used in the present invention is not particularly limited, and one kind may be used alone or two or more kinds may be used in combination. Particularly, the one represented by the formula (2) is preferable. The value of m in the formula (2) is an average value, preferably 1 to 6, and if m exceeds 6, fluidity may decrease and moldability may decrease.

[Chemical 3] The dicyclopentadiene type epoxy resin of the present invention, compared with the conventional orthocresol novolac type epoxy resin,
It has extremely low moisture absorption, has a low elastic modulus in a high temperature range exceeding the glass transition temperature (Tg), and has excellent adhesiveness to metals such as lead frames. Therefore, the thermal stress at the time of soldering of surface mounting can be reduced, and the epoxy resin composition excellent in solder reflow reliability can be obtained. Further, other epoxy resins may be used in combination as long as the characteristics of the dicyclopentadiene type epoxy resin of the present invention are not impaired. Epoxy resins that can be used in combination include monomers and oligomers having two or more epoxy groups in one molecule,
It refers to polymers in general, and its molecular weight and molecular structure are not particularly limited, and examples thereof include biphenyl type epoxy resin, bisphenol type epoxy resin, stilbene type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, triphenol methane. Type epoxy resin, alkyl-modified triphenol methane type epoxy resin, triazine nucleus-containing epoxy resin, phenol aralkyl type epoxy resin (having a phenylene skeleton, biphenyl skeleton, etc.), naphthol type epoxy resin, etc. Or two or more kinds may be used in combination. The content of the dicyclopentadiene type epoxy resin of the present invention is preferably 20 to 100% by weight, and particularly preferably 50 to 100% by weight based on the total epoxy resin.

As the phenol resin used in the present invention,
Monomers, oligomers, and polymers having two or more phenolic hydroxyl groups in one molecule are generally mentioned, and their molecular weight and molecular structure are not particularly limited. For example, phenol novolac resin, cresol novolac resin, dicyclopentadiene-modified phenol Resin, terpene modified phenol resin, triphenol methane type resin, phenol aralkyl resin (having phenylene skeleton, biphenyl skeleton, etc.), naphthol resin, etc.
One type may be used alone, or two or more types may be used in combination. In particular, phenol novolac resin, dicyclopentadiene modified phenol resin, phenol aralkyl resin, terpene modified phenol resin and the like are preferable.

The curing accelerator used in the present invention may be any one as long as it accelerates the curing reaction between the epoxy group and the phenolic hydroxyl group, and those generally used for sealing materials can be used. For example, 1,8-diazabicyclo (5,4,0) undecene-7, triphenylphosphine, 2-methylimidazole, tetraphenylphosphonium tetraphenylborate, triphenylphosphine adducted with benzoquinone and the like can be mentioned. One type may be used alone, or two or more types may be used in combination.

As the inorganic filler used in the present invention, those generally used for sealing materials can be used. Examples thereof include fused silica, crystalline silica, talc, alumina, silicon nitride and aluminum hydroxide, and these may be used alone or in combination of two or more. Among these, the total amount of fused silica with high sphericity,
Alternatively, it is preferable to use partially crushed silica. The inorganic filler preferably has an average particle size of 5 to 30 μm and a maximum particle size of 74 μm or less. Also, the filling amount can be increased by mixing particles having different sizes. As the inorganic filler, one that has been surface-treated with a silane coupling agent or the like in advance may be used. The content of the inorganic filler is 60 to 95% by weight in the total epoxy resin composition from the balance of moldability and solder reflow reliability.
Is preferred. If it is less than 60% by weight, the solder reflow reliability is lowered due to an increase in moisture absorption rate, and if it exceeds 95% by weight, there may be a problem in formability such as wire sweep and pad shift.

The cyclic phosphazene compound used in the present invention may be any compound having a cyclic phosphazene structure in the compound, and examples thereof include a compound having a structure represented by the general formula (1). Acts as. The flame-retardant mechanism of the phosphazene compound has the carbonization-promoting effect of the contained phosphorus, that is, the effect of protecting the surface of the cured product and blocking oxygen by forming an incombustible carbonized layer on the surface of the cured product. This is because the obtained nitrogen produces nitrogen gas at the time of thermal decomposition due to the contained nitrogen, and shuts off oxygen even in the gas phase. The phosphazene compound can impart high flame retardancy due to the flame retardant effect that works in both the solid phase and the gas phase.

R in the general formula (1) is generally an alkyl group, an alkenyl group, an alkoxy group, an aryl group, an aryloxy group, etc., but also an amino group, a mercapto group, a hydroxy group, a fluoroalkyl group, etc. As represented by
It may contain N, S, O, F atoms and the like.
These cyclic phosphazene compounds may be used alone or in combination of two or more. Furthermore, 6 of trimer
It is more preferred that the member ring is the main component. Specific examples of the cyclic phosphazene compound represented by the general formula (1) include hexapropylcyclotriphosphazene, tetraethoxydipropoxycyclotriphosphazene, hexaphenoxycyclotriphosphazene, hexaanilinocyclotriphosphazene, hexakis (3 −
Examples include mercaptopropyl) cyclotriphosphazene and hexakis (heptafluoropropyloxy) cyclotriphosphazene. As R in the general formula (1), an aryloxy group is preferable from the viewpoints of heat resistance and moisture resistance, and among 2n Rs from the viewpoint of compatibility with the epoxy resin and fluidity of the epoxy resin composition. More preferably, at least n are phenoxy groups.

As another example of the cyclic phosphazene compound, a compound in which one cyclic phosphazene is bonded to another cyclic phosphazene through another organic group in order to enhance flame retardancy is also preferable. In this case, the cyclic phosphazenes may be of the same type or of different types. For example, a compound in which a part of R of one cyclic phosphazene represented by the general formula (1) is bonded to a part of R of another cyclic phosphazene through another organic group or R, These other organic groups may be not only a single group but also a group combined with other groups. For example, a compound having a phosphazene group at both ends of the organic group may be used. Examples of another organic group that bonds these cyclic phosphazenes to each other include:
A hydrogen atom is removed from an organic group obtained by removing a hydrogen atom from a hydroxyl group of a diol compound such as 1,6-dioxyhexane or a dihydroxy compound such as a bifunctional phenol compound such as hydroquinone, 4,4′-biphenol and bisphenol F. The removed groups and the like can be preferably used.

The content of the cyclic phosphazene compound of the present invention is preferably 0.01 to 15% by weight, more preferably 0.1 to 10% by weight, based on the total epoxy resin composition.
If it is less than 0.01% by weight, flame retardancy is insufficient, and if it exceeds 15% by weight, curability, heat resistance and strength are lowered and moisture absorption is increased, which is not preferable.

The phosphazene compound has the property of imparting high flame retardancy, but a large amount of compounding is required to achieve sufficient flame retardancy. However, if a large amount is compounded, the solder reflow resistance will decrease. Therefore, in order to prevent these physical properties from deteriorating, when the dicyclopentadiene type epoxy resin of the present invention is used in combination, the solder reflow reliability can be improved.

The epoxy resin composition of the present invention comprises (A)-
In addition to the component (E), a flame retardant such as a brominated epoxy resin or antimony trioxide may be contained if necessary, but the stability of the electrical characteristics of the semiconductor device at a high temperature of 150 to 200 ° C. For required applications, the content of bromine atom and antimony atom is preferably less than 0.1% by weight in the total epoxy resin composition, and more preferably not contained completely. If either the bromine atom or the antimony atom is 0.1% by weight or more, the resistance value of the semiconductor device increases with time when left at high temperature, and eventually the gold wire of the semiconductor element is broken. Can occur. Also, from the viewpoint of environmental protection, it is desirable that the content of each of bromine atom and antimony atom is less than 0.1% by weight, and that the content of bromine atom and antimony atom is as small as possible. The epoxy resin composition of the present invention contains components (A) to (E) as essential components,
In addition to these, various additives such as a silane coupling agent, a coloring agent such as carbon black, a release agent such as natural wax and a synthetic wax, and a low stress additive such as silicone oil and rubber are appropriately blended as necessary. It doesn't matter.
Further, the epoxy resin composition of the present invention is obtained by sufficiently and uniformly mixing the components (A) to (E) and other additives with a mixer or the like, and then melt-kneading the mixture with a hot roll or a kneader. It is obtained by crushing after cooling. By using the epoxy resin composition of the present invention, various electronic components such as semiconductor elements are sealed and semiconductor devices are manufactured by curing molding by a conventional molding method such as transfer molding, compression molding or injection molding. do it.

[0016]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. The mixing ratio is parts by weight. <Example 1> Dicyclopentadiene type epoxy resin [Dainippon Ink and Chemicals, Inc., HP 7200 softening point 60 ° C, epoxy equivalent 263] 6.5 parts by weight Phenol aralkyl resin (softening point 75 ° C, hydroxyl equivalent 174) ) 4.3 parts by weight Triphenylphosphine 0.2 parts by weight Fused spherical silica (average particle size 20 μm) 87.0 parts by weight Phosphazene compound represented by formula (3) 1.0 parts by weight

[Chemical 4] 0.3 parts by weight of carbon black 0.5 parts by weight of carnauba wax 0.4 parts by weight of other additives were mixed at room temperature with a mixer, and then the surface temperature was 90%.
The mixture was kneaded using two rolls at 45 ° C and 45 ° C, 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, mold temperature 175 ° C.
It was measured at an injection pressure of 6.9 MPa and a curing time of 120 seconds.
The unit is cm. Curing: Using a transfer molding machine, mold temperature 1
Molding was performed at 75 ° C., injection pressure of 9.6 MPa, and curing time of 120 seconds. The surface hardness of the runner 10 seconds after the mold was opened was measured with a Bacol hardness meter # 935. The Bacol hardness is an index of curability, and the larger the value, the better the curability. Moisture absorption rate: Using a low-pressure transfer molding machine, a mold temperature of 175 ° C., an injection pressure of 3.7 MPa, a curing time of 120 seconds, and a disk having a diameter of 50 mm and a thickness of 3 mm were molded and molded at 175 ° C.
It was post-cured in 8 hours, left for 168 hours in an environment of 85 ° C. and 85% relative humidity, and the weight change was measured to obtain the moisture absorption rate. The unit is% by weight. Bending strength during heating: 240 ° C according to JIS K 6911
The bending strength was measured. The unit is N / mm ² . Flame resistance: Mold temperature 1 using low pressure transfer molding machine
A test piece (127 mm × 12.7 mm × 3.2 mm) was molded at 75 ° C., an injection pressure of 11.0 MPa, and a curing time of 120 seconds, post-cured at 175 ° C. for 8 hours, and then according to the UL-94 vertical method. The flame retardancy was determined by measuring ΣF and Fmax. Solder reflow reliability: 80 pQFP (2 mm thick, chip size 9.0 mm x 9.0 mm) was molded using a low-pressure transfer molding machine at a mold temperature of 175 ° C, an injection pressure of 9.6 MPa, and a curing time of 120 seconds. It was post-cured at 175 ° C. for 8 hours, left standing at 85 ° C. and 85% relative humidity for 168 hours, and then immersed in a solder bath at 260 ° C. for 10 seconds. Observed with a microscope, crack occurrence rate [(crack occurrence rate) =
(Number of external cracked packages) / (total number of packages) × 100] was determined. Units%. Further, the ratio of the semiconductor element area to the peeled area of the cured product of the epoxy resin composition was measured using an ultrasonic flaw detector, and the peeled rate [(peeled rate) =
(Peeling area) / (Semiconductor element area) × 100] was determined. Units%. High temperature storage characteristics: Mold temperature 175 ° C., injection pressure 9.6 MPa, curing time 120 using low pressure transfer molding machine
16 pDIP in seconds (chip size 3.0 mm x 3.5 m
m) is molded and post-cured at 175 ° C. for 8 hours, and then a high temperature storage test (185 ° C., 1000 hours) is performed, and a package in which the electric resistance between wirings increases by 20% from the initial value is determined to be defective. did. The percentage of defective packages (defective percentage) in 15 packages is shown in percentage. Units%. Bromine atom and antimony atom content rate: compression molding was carried out at a pressure of 3.7 MPa to a diameter of 40 mm and a thickness of 5 to 7 mm, and the obtained molded product was analyzed using a fluorescent X-ray analyzer to measure the bromine atom content in all epoxy resin compositions. , The content of antimony atoms was quantified. The unit is% by weight.

<Example 2, Comparative Examples 1 to 3> According to the formulation of Table 1, an epoxy resin composition was 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. The cyclic phosphazene compound used in Example 2 is represented by Structural Formula (4).

[Chemical 5] The biphenyl type epoxy resin used in Comparative Example 2 was 4,4 ′.
-Bis (2,3-epoxypropoxy) -3,3 ',
It has 5,5'-tetramethylbiphenyl as a main component, a melting point of 105 ° C, and an epoxy equivalent of 191. The brominated bisphenol A type epoxy resin used in the comparative example has an epoxy equivalent of 365 and a bromine atom content of 48% by weight.

[0019]

[Table 1]

[0020]

According to the present invention, an epoxy resin composition for semiconductor encapsulation, which does not contain a halogen-based flame retardant or an antimony compound and is excellent in moldability, flame retardancy, and solder reflow reliability,
And a semiconductor device is obtained.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 23/31 F term (reference) 4J002 CC032 CC072 CD031 CD041 DE147 DJ007 DJ017 DJ047 EU096 EU116 EW016 EW158 EY016 FD017 FD138 FD142 FD156 GQ05 4J036 AK19 DA01 DA02 DA04 DC09 DC41 DD07 DD09 FA01 FA02 FA05 FA06 FA12 FB07 FB08 JA07 4M109 AA01 CA21 EA03 EB03 EB04 EB12 EC20

Claims (5)

[Claims] 1. (A) dicyclopentadiene type epoxy resin, (B) phenol resin, (C) curing accelerator,
An epoxy resin composition for semiconductor encapsulation, which comprises (D) an inorganic filler and (E) a cyclic phosphazene compound as essential components. 2. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the cyclic phosphazene compound is a cyclic phosphazene compound represented by the general formula (1). [Chemical 1] (In the formula, n represents an integer of 3 to 7, and R represents the same or different organic groups.) 3. The epoxy resin composition for semiconductor encapsulation according to claim 2, wherein at least n of 2n R of the cyclic phosphazene compound represented by the general formula (1) are phenoxy groups. 4. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the total amount of bromine atom and antimony atom contained in the entire epoxy resin composition is less than 0.1% by weight. . 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.