JP2003147053A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin composition for semiconductor sealing not containing a halogen-based flame retardant and an antimony compound and excellent in moldability, flame retardance, resistance to soldering, reliability to moisture resistance and high-temperature storage property. SOLUTION: This epoxy resin composition for semiconductor sealing consists essentially of (A) an epoxy resin, (B) a phenol resin, (C) a curing accelerator composed of an adduct of triphenylphosphine with 1,4-benzoquinone, (D) an inorganic filler and (E) a phosphazene compound.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition for semiconductor encapsulation and a semiconductor device which does not contain a halogen-based flame retardant and an antimony compound and is excellent in flame retardancy, moldability and high temperature storage characteristics. .

[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, halogen-based flame retardants and antimony compounds such as antimony trioxide, antimony tetroxide and antimony pentoxide are usually blended in these epoxy resin compositions. 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. When the semiconductor device sealed with the epoxy resin composition containing the halogen-based flame retardant and the antimony compound is stored at high temperature,
It is known that the thermally decomposed halide is released from these flame retardant components, corrodes the joint part of the semiconductor element, and impairs the reliability of the semiconductor device.Halogen flame retardants and antimony compounds are used as flame retardants. There is a demand for an epoxy resin composition that can achieve V-0 of UL-94 as a flame-retardant grade.

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 called a high temperature storage characteristic. As a method for improving the characteristics, a method using diantimony pentoxide (JP-A-55-
No. 146950), a method of combining antimony oxide and organic phosphine (Japanese Patent Laid-Open No. 61-53321), etc., and their effects have been confirmed, but recent high-temperature storage characteristics required for semiconductor devices have high required levels. On the other hand, some epoxy resin compositions are unsatisfactory. Therefore, by using a cyclic phosphazene compound as proposed in JP-A-10-259292, sufficient flame retardancy is achieved without using a bromine compound and an antimony compound, but the curability is lowered. The solder resistance tends to decrease due to mold fouling due to occurrence of bleeding, decrease in strength, increase in moisture absorption rate, and the like. That is, there is a demand for an epoxy resin composition that maintains flame retardancy without using a halogen-based flame retardant and an antimony compound, and that has excellent moldability, high-temperature storage characteristics, and solder resistance.

[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 a semiconductor encapsulating epoxy resin composition having excellent solder resistance and high-temperature storage characteristics, and a semiconductor device obtained by encapsulating a semiconductor element using the same.

[0005]

The present invention provides [1]
(A) epoxy resin, (B) phenol resin, (C) phosphine compound represented by the general formula (1) and general formula (2)
The epoxy resin composition for semiconductor encapsulation, comprising a curing accelerator consisting of an adduct with a quinone compound represented by the formula (D), an inorganic filler (D) and a phosphazene compound (E) as essential components.

[0006]

[Chemical 5] (In the formula, R1 to R3 are each a substituent or an unsubstituted group having 1 to 1 carbon atoms.
12 alkyl groups or substituted or unsubstituted 6 to 6 carbon atoms
12 aryl groups, all of which may be the same or different)

[0007]

[Chemical 6] (In the formula, R4 to R6 represent a hydrogen atom or a hydrocarbon having 1 to 12 carbon atoms, and all may be the same or different.
And R5 may combine to form a ring structure)

[2] The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the phosphazene compound is a cyclic phosphazene compound, and [3] the cyclic phosphazene compound is
The epoxy resin composition for semiconductor encapsulation according to the item [1] or [2], which is a compound represented by the general formula (3):

[0009]

[Chemical 7] (In the formula, n is an integer of 3 to 7, and R7 are the same or different organic groups)

[4] The epoxy resin composition for semiconductor encapsulation according to the item [3], wherein at least n out of 2n R7 of the compound represented by the general formula (3) are phenoxy groups, [5] The curing accelerator is represented by the formula [4] [1]
The epoxy resin composition for semiconductor encapsulation according to the item [2], [3] or [4],

[0011]

[Chemical 8]

[6] Item [1], Item [2], Item [3]
A semiconductor device, which is obtained by encapsulating a semiconductor element using the epoxy resin composition for encapsulating a semiconductor according to item [4] or [5].

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The epoxy resin used in the present invention refers to all monomers, oligomers and polymers having two or more epoxy groups in one molecule, and its molecular weight and molecular structure are not particularly limited. For example, 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, Examples thereof include a dicyclopentadiene-modified phenol type epoxy resin, a phenol aralkyl type epoxy resin (having a phenylene skeleton and a diphenyl skeleton), a naphthol type epoxy resin, and the like, and these may be used alone or in combination. From the viewpoint of improving solder resistance, a biphenyl type epoxy resin and a phenol aralkyl type epoxy resin having a biphenyl skeleton are particularly preferable.

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 the molecular weight and the molecular structure thereof 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 a phenylene skeleton, diphenyl skeleton, etc.), naphthol resin and the like, and these may be used alone or in combination. In particular, phenol novolac resin, dicyclopentadiene modified phenol resin, phenol aralkyl resin, terpene modified phenol resin and the like are preferable. The blending amount of these is preferably 0.8 to 1.3 in terms of the ratio of the number of epoxy groups of all epoxy resins to the number of phenolic hydroxyl groups of all phenolic resins.

The curing accelerator used in the present invention comprises an adduct of the phosphine compound represented by the general formula (1) and the quinone compound represented by the general formula (2), particularly preferably the formula (4). A curing accelerator in which 1,4-benzoquinone and triphenylphosphine are added is desirable. The epoxy resin composition using the curing accelerator represented by the formula (4) cures faster and has improved moldability, and the cured product has a low moisture absorption rate and improved strength at the time of heating, and thus has good solder resistance. can get. The curing accelerator, which is an adduct of the phosphine compound represented by the general formula (1) and the quinone compound represented by the general formula (2), is contained in an amount of 30% by weight or more in the entire curing accelerator. You may use together with another hardening accelerator. If it is less than 30% by weight, the effect of the present invention may not be sufficiently exhibited. The curing accelerator to be used in combination may be one that accelerates the curing reaction between the epoxy group and the phenolic hydroxyl group, and those generally used for the encapsulating material can be used. For example, 1,8-diazabicyclo (5,4,0) undecene-7, triphenylphosphine, 2-methylimidazole, tetraphenylphosphonium / tetraphenylborate and the like can be mentioned.

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. Among these, it is preferable to use the fused silica having a high sphericity entirely or in part together with the crushed silica. The average particle size of the inorganic filler is 5 to 30 μm,
The maximum particle size is preferably 74 μm or less. The blending amount can be increased by mixing particles having different particle 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 blending amount of the inorganic filler is preferably 60 to 95% by weight in the total epoxy resin composition from the viewpoint of balance between moldability and solder resistance. If it is less than 60% by weight, the solder resistance will decrease with an increase in the moisture absorption rate, and if it exceeds 95% by weight, problems such as wire sweep and pad shift may occur.

The phosphazene compound used in the present invention has a skeleton structure represented by the general formula (5) and acts as a flame retardant, and the flame retardant action is to promote carbonization by phosphorus in the compound, that is, the epoxy resin composition. By forming a non-combustible carbonized layer on the surface of the cured product, it protects the surface of the cured product and blocks oxygen, and nitrogen gas is generated during thermal decomposition by nitrogen in the compound, and also blocks oxygen in the gas phase. It is presumed to be due to this. It is considered that the phosphazene compound imparts high flame retardancy because of the flame retardant effect acting in both the solid phase and the gas phase. The phosphazene compound having a skeleton represented by the general formula (5) includes a straight-chain type and a cyclic type.

[0018]

[Chemical 9]

Examples of R8 in the general formula (5) include an alkyl group, an alkenyl group, an alkoxy group, an aryl group, an aryloxy group and the like, and a group containing nitrogen, sulfur, oxygen, a fluorine atom and the like, for example, Amino group, mercapto group,
Examples thereof include a hydroxy group and a fluoroalkyl group.

The linear phosphazene compound having a skeleton represented by the general formula (5) is preferably the one represented by the general formula (6), n is an integer of 3 to 1000, and R9 is an alkyl group, Examples thereof include an alkenyl group, an alkoxy group, an aryl group, an aryloxy group and the like, further nitrogen,
Examples thereof include a group containing a sulfur atom, an oxygen atom, a fluorine atom and the like, such as an amino group, a mercapto group, a hydroxy group and a fluoroalkyl group. Of these, aryloxy groups are preferable from the viewpoint of heat resistance and moisture resistance, and from the viewpoint of compatibility with resin components and fluidity of the epoxy resin composition, at least n of 2n R9 are preferably phenoxy groups.

[0021]

[Chemical 10]

The cyclic phosphazene compound having the skeleton represented by the general formula (5) is preferably the compound represented by the general formula (3), n is an integer of 3 to 7, and R7 is R8 of the general formula (5). Is the same as Of these, an aryloxy group is preferable from the viewpoint of heat resistance and moisture resistance, and from the viewpoint of compatibility with the resin component and fluidity of the epoxy resin composition, at least n of 2n R7 is preferably a phenoxy group. A more desirable compound has a trimeric 6-membered ring structure, and may contain a small amount of another cyclic compound.

Specific examples of the cyclic phosphazene compound represented by the general formula (3) include hexapropylcyclotriphosphazene, tetraethoxydipropoxycyclotriphosphazene, hexaphenoxycyclotriphosphazene, hexaanilinocyclotriphosphazene, hexakis (3-). Examples include mercaptopropyl) cyclotriphosphazene and hexakis (heptafluoropropyloxy) cyclotriphosphazene.

Another preferred cyclic phosphazene compound included in the present invention is at least one cyclic phosphazene compound represented by the general formula (3) via a divalent organic group in order to further improve flame retardancy. , Those having a structure bonded to at least one other cyclic phosphazene compound. The divalent organic group that bonds the cyclic phosphazene compounds to each other is a group obtained by removing two hydrogen atoms from a hydroxyl group of a diol compound such as 1,6-dioxyhexane, or hydroquinone, 4,4′-biphenol, bisphenol. A group obtained by removing two hydrogen atoms from the hydroxyl group of a bifunctional phenol compound such as F is preferable. Mutual cyclic phosphazene compounds may be the same or different. The structure in which cyclic phosphazene compounds are bonded to each other is represented by the formula (7)
However, the present invention is not limited to this. The phosphazene compound is described in JP-A-55-27.
It is disclosed in Japanese Patent Laid-Open No. 344, Japanese Patent Laid-Open No. 11-181429, and the like.

[0025]

[Chemical 11]

The amount of the phosphazene compound used in the present invention is preferably 0.02 to 5% by weight, more preferably 0.1 to 5% by weight, based on the total epoxy resin composition.
If it is less than 0.02% by weight, flame retardancy is insufficient, and if it exceeds 5% by weight, curability, heat resistance and strength may be deteriorated and moisture absorption may be increased. The method of adding the phosphazene compound is not particularly limited, but, for example, a method of preliminarily melting and mixing with an epoxy resin or a phenol resin, or finely pulverizing into 1 mm or less and charging into a kneader is effective for improving flame retardancy.

The epoxy resin composition of the present invention comprises (A)-
In addition to the component (E), a brominated epoxy resin, a flame retardant such as antimony trioxide may be added 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 completely contained. 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. 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 comprises (A)-
The component (E) is an essential component, but in addition to this, a silane coupling agent, a coloring agent such as carbon black, a release agent such as natural wax or synthetic wax, and a low stress addition such as silicone oil or rubber, if necessary. Various additives such as agents may be appropriately blended. The epoxy resin composition of the present invention is prepared by thoroughly and uniformly mixing the components (A) to (E) and other additives with a mixer or the like, and then melt-kneading them with a hot roll or a kneader and cooling them. Obtained by crushing. 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.

[0029]

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 Biphenyl type epoxy resin (Japan Epoxy Resin Co., Ltd., YX-4000, melting point 105 ° C., epoxy equivalent 191) 5.9 parts by weight Phenol aralkyl resin (Mitsui Chemicals Co., Ltd., XLC-LL, softened) Point 75 ° C., hydroxyl equivalent 174) 5.1 parts by weight Curing accelerator represented by the formula (4) 0.2 parts by weight fused spherical silica (average particle size 20 μm) 86.6 parts by weight Phosphazene represented by the formula (7) Compound 1.0 parts by weight Carbon black 0.3 parts by weight Carnauba wax 0.5 parts by weight Other additives 0.4 parts by weight were mixed at room temperature using 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: Mold temperature 1 using low pressure transfer molding machine
Molding was performed at 75 ° C., injection pressure of 6.9 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. Bacol hardness is an index of curability, and the larger the value, the better the curability. Moisture absorption rate: Mold temperature 1 using low pressure transfer molding machine
A disc having a diameter of 50 mm and a thickness of 3 mm was molded at 75 ° C., an injection pressure of 7.9 MPa, and a curing time of 120 seconds, and then molded at 175 ° C., 8
Post-cured in 1 hour, under an environment of 85 ° C and 85% relative humidity
After standing for 68 hours, the weight change was measured to determine 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 9.8 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 resistance: 80 pQFP (2 mm thickness, chip size 9.0 mm ×) at a mold temperature of 175 ° C., an injection pressure of 8.3 MPa and a curing time of 120 seconds using a low pressure transfer molding machine.
9.0 mm), and post-cured at 175 ° C. for 8 hours,
Leave at 85 ° C and 85% relative humidity for 168 hours, then 2
It was immersed in a solder bath at 40 ° C. for 10 seconds. Observe with a microscope,
The crack generation rate [(crack generation rate) = (number of external crack generation packages) / (total number of packages) × 100] was obtained. Units%. 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) = (peeled area) / (semiconductor element area) × 100]. I asked. Units%. High temperature storage characteristics: Mold temperature 175 ° C., injection pressure 9.8 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 rate) out of 15 packages is shown in percentage. Units%.

Examples 2 and 3, Comparative Examples 1 to 3 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. The phosphazene compound used in Example 2 is represented by the formula (8).

[0032]

[Chemical 12]

The brominated bisphenol A type epoxy resin used in the comparative example had an epoxy equivalent of 365 and a bromine atom content of 4
8% by weight.

[0034]

[Table 1]

[0035]

EFFECTS OF THE INVENTION 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, is obtained. Excellent flammability and high temperature storage characteristics.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 23/31 F term (reference) 4J002 CC032 CD001 DE146 DF016 DJ016 DJ046 EW157 FD136 FD137 GQ05 HA01 4J036 AA01 AC01 AC02 AC08 AC18 AD04 AD08 DA09 DD07 FA02 FB07 JA07 KA01 4M109 AA01 BA01 CA21 EA02 EB03 EB04 EB07 EB12 EC01 EC05 EC14 EC20

Claims (6)

[Claims] 1. A curing accelerator comprising an adduct of (A) an epoxy resin, (B) a phenol resin, (C) a phosphine compound represented by the general formula (1) and a quinone compound represented by the general formula (2). An epoxy resin composition for semiconductor encapsulation, comprising (D) an inorganic filler and (E) a phosphazene compound as essential components. [Chemical 1] (In the formula, R1 to R3 are each a substituent or an unsubstituted group having 1 to 1 carbon atoms.
12 alkyl groups or substituted or unsubstituted 6 to 6 carbon atoms
12 aryl groups, all of which may be the same or different) (In the formula, R4 to R6 represent a hydrogen atom or a hydrocarbon having 1 to 12 carbon atoms, and all may be the same or different.
And R5 may combine to form a ring structure) 2. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the phosphazene compound is a cyclic phosphazene compound. 3. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the cyclic phosphazene compound is a compound represented by the general formula (3). [Chemical 3] (In the formula, n is an integer of 3 to 7, and R7 are the same or different organic groups) 4. The epoxy resin composition for semiconductor encapsulation according to claim 3, wherein at least n out of 2n R7 of the compound represented by the general formula (3) are phenoxy groups. 5. The epoxy resin composition for semiconductor encapsulation according to claim 1, 2, 3 or 4, wherein the curing accelerator has the formula (4). [Chemical 4] 6. A semiconductor device obtained by encapsulating a semiconductor element using the epoxy resin composition for encapsulating a semiconductor according to claim 1, 2, 3, 4 or 5.