JP2001335620A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin composition for semiconductor sealing which has excellent moldability, soldering stress resistance, high-temperature storing characteristics and flame retardance without containing a bromine compound and an antimony compound. SOLUTION: The composition is characterized, as the essential components, by containing (A) an epoxy resin, (B) a modified phenol resin obtained by polycondensing a petroleum-based heavy oil or pitches with a formaldehyde polymer and phenols in the presence of an acidic catalyst, (C) an inorganic filler, (D) a curing accelerator and (E) a cyclic phosphazene compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to moldability, flame retardancy,
The present invention relates to an epoxy resin composition having excellent solder stress resistance and a semiconductor device.

[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, and these epoxy resin compositions usually have flame retardancy. For this purpose, a bromine-containing organic compound and an antimony compound are blended. However, the environment
From the viewpoint of hygiene, there is a demand for the development of an epoxy resin composition for semiconductor encapsulation having excellent flame retardancy without using a bromine-containing organic compound and an antimony compound. Furthermore, when a semiconductor device is stored at a high temperature of 150 to 200 ° C. for a long time, a bromine-containing organic compound or an antimony compound, which is a flame retardant component, is known to cause an increase in the resistance value of the semiconductor device or breakage of a gold wire. ing. From this viewpoint, development of an epoxy resin composition for semiconductor encapsulation which is excellent in high-temperature storage characteristics without using a bromine-containing organic compound or an antimony compound has been awaited. Also, when a semiconductor device is mounted on a printed circuit board, solder containing lead (tin-lead alloy) is used. Similarly, from the viewpoint of environment and sanitation, solder containing lead (tin-lead alloy) is used. ) Is not desired. However, in the case of a solder containing lead (tin-lead alloy), the melting point is 183 ° C., so that the temperature during the soldering process is 220 ° C.
On the other hand, a solder containing no lead, such as a tin-silver alloy, has a high melting point and a temperature of about 260 ° C. during the soldering process. Development of an epoxy resin composition for semiconductor encapsulation has been desired. Conventionally, to improve solder stress resistance, a combination of a low-viscosity epoxy resin / curing agent and a high filling of inorganic filler is generally used, but a low-viscosity epoxy resin / curing agent is cured. Because of poor moldability, there were difficulties in moldability, such as poor mold release properties and low hardness of molded articles.
On the other hand, a novolak type phenol resin is excellent in curability, but it is difficult to highly fill an inorganic filler due to its high viscosity. Therefore, even if the inorganic filler is not highly filled, a curing agent having good solder stress resistance and flame retardancy is required. An epoxy resin composition that completely satisfies good moldability and solder stress resistance has not yet been proposed.

[0003]

The present invention is directed to an epoxy resin for semiconductor encapsulation which does not contain a bromine-containing organic compound and an antimony compound and has excellent moldability, solder stress resistance, flame retardancy, and high-temperature storage characteristics. A composition and a semiconductor device using the same are provided.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a method comprising the steps of: polycondensing (A) an epoxy resin, (B) a petroleum heavy oil or pitches, a formaldehyde polymer and a phenol in the presence of an acid catalyst. An epoxy resin composition for semiconductor encapsulation comprising, as essential components, a modified phenolic resin, (C) an inorganic filler, (D) a curing accelerator, and (E) a cyclic phosphazene compound. A semiconductor device in which a semiconductor element is sealed.

[0005]

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. For example, biphenyl epoxy resin, bisphenol epoxy resin, stilbene epoxy resin, orthocresol novolak epoxy resin, phenol novolak epoxy resin, triphenolmethane epoxy resin, alkyl-modified triphenolmethane epoxy resin, epoxy containing triazine nucleus Resin, dicyclopentadiene-modified phenol type epoxy resin, phenol aralkyl type epoxy resin, naphthol aralkyl type epoxy resin, etc., may be used alone or in combination. Among these epoxy resins, an orthocresol novolak type epoxy resin, a crystalline epoxy resin having a melting point of 50 to 150 ° C., and the like are preferable. Such a crystalline epoxy resin has a rigid structure such as a biphenyl skeleton, a bisphenol skeleton, or a stilbene skeleton in its main chain, and has relatively low molecular weight and thus exhibits crystallinity. The crystalline epoxy resin is a solid that crystallizes at room temperature, but rapidly melts and changes to a low-viscosity liquid in a temperature range higher than the melting point. The melting point of the crystalline epoxy resin indicates the temperature at the top of the endothermic peak of crystal melting when the temperature is raised from room temperature at a rate of 5 ° C./min using a differential scanning calorimeter.

The modified phenolic resin used in the present invention obtained by polycondensing heavy petroleum oil or pitches, formaldehyde polymer and phenol in the presence of an acid catalyst has characteristics of low viscosity and low hygroscopicity. Have. This modified phenol resin is disclosed in, for example, JP-A-7-25233.
No. 9 and JP-A-9-216927. Petroleum heavy oil, pitches, for example, crude oil distillation residue, catalytic cracking residual oil, hydrocracking residual oil,
Residual oils of the thermally decomposed products of LPG or naphtha, and those obtained as reduced-pressure distillates of these residual oils, extracts obtained by solvent extraction, or heat-treated products. Examples of the formaldehyde polymer include a linear polymer such as paraformaldehyde and polyoxymethylene, and a cyclic polymer such as trioxane. Examples of phenols include phenol, cresol, hydroquinone,
Bisphenol A, bisphenol F and the like can be mentioned, and these may be used alone or as a mixture. As the acid catalyst used in the polycondensation step, Bronsted acid can be used.
As the Brönsted acid, for example, toluenesulfonic acid, xylenesulfonic acid, hydrochloric acid, sulfuric acid and the like are used.
The modified phenolic resin of the present invention has low hygroscopicity, low elasticity when heated, and is excellent in solder stress resistance and flame retardancy even when the inorganic filler is not highly filled by being combined with a novolak type epoxy resin. Epoxy resin composition can be obtained.

[0007] The softening point of the modified phenolic resin of the present invention is preferably from 60 to 120 ° C. If the temperature is lower than 60 ° C., there is a difficulty in handling workability. If the temperature exceeds 120 ° C., the fluidity of the epoxy resin composition is inferior, so that the inorganic filler may not be highly filled. In order to maximize low moisture absorption and flame retardancy, the hydroxyl equivalent is preferably 150 to 300 g / eq so that the polycyclic aromatic system in the modified phenolic resin of the present invention is increased. in this case,
There is a feature that flame retardancy can be maintained without blending a flame retardant such as brominated epoxy resin and antimony trioxide. If the hydroxyl group equivalent is less than 150 g / eq, low moisture absorption and improvement in flame retardancy will be insufficient, and if it exceeds 300 g / eq, curability will be poor. The modified phenolic resin of the present invention preferably has a melt viscosity at 150 ° C. of 5 to 30 Pa · s. 5Pa · s
If the amount is less than the above range, the moisture resistance and the curability of the epoxy resin composition deteriorate, which is not preferable. If it exceeds 30 Pa · s, the fluidity of the epoxy resin composition is inferior, so that the inorganic filler may not be highly filled. 150 ° C. of the present invention
Was measured using an ICI viscometer. The modified phenolic resin of the present invention may be used in combination with other phenolic resins as long as the properties of the modified phenolic resin of the present invention are not impaired. It is preferably at least 30% by weight, particularly preferably at least 50% by weight in the phenol resin. If the amount is less than 30% by weight, characteristics of the modified phenolic resin of the present invention, such as low hygroscopicity and improved flame retardancy, may not be obtained. Examples of the phenol resin used in combination include a phenol novolak resin, a phenol aralkyl resin, a dicyclopentadiene-modified phenol resin, and a terpene-modified phenol resin. These may be used alone or as a mixture. The equivalent ratio of the epoxy group of all epoxy resins used in the present invention to the phenolic hydroxyl group of all phenolic resins is preferably 0.5 to 2, and more preferably 0.7 to 1.5. If the ratio is out of the range of 0.5 to 2, the moisture resistance, the curability and the like are undesirably reduced.

The kind of the inorganic filler used in the present invention is not particularly limited, and an inorganic filler generally used for a sealing material can be used. For example, fused silica, crystalline silica, secondary aggregated silica, alumina, titanium white, aluminum hydroxide, talc, clay, glass fiber and the like can be mentioned, and these may be used alone or in combination. Of these, it is preferable to use the fused silica having a high sphericity in its entirety or in combination with partially 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. Further, by mixing particles having different particle sizes, the filling amount can be increased. As the inorganic filler, a material which has been surface-treated with a silane coupling agent or the like in advance may be used. The content of the inorganic filler is 65 to 65 in the total epoxy resin composition.
85% by weight is preferred. The inorganic filler that does not burn even when heated has the effect of removing thermal energy when exposed to a flame and improving the flame retardancy of a cured product of the epoxy resin composition. If the compounding amount is less than 65% by weight, the epoxy resin composition contains a large amount of flammable organic substances, so that the epoxy resin composition becomes a cured product having a small heat capacity and is liable to burn. 85% by weight
Exceeding the range is not preferable because the rigidity of the molded product is increased and cracks occur during combustion. In this case, the combustion component inside the molded article ignites because it gushes out of the crack,
Burn.

The curing accelerator used in the present invention is not particularly limited as long as it promotes the reaction between the epoxy group and the phenolic hydroxyl group. For example, 1,8-diazabicyclo (5,4,0) undecene-7 is used. Such as diazabicycloalkene and derivatives thereof, triphenylphosphine, organic phosphines such as methyldiphenylphosphine, tetraphenylphosphonium / tetraphenylborate, tetraphenylphosphonium / tetrabenzoic acid borate, tetraphenylphosphonium / tetranaphthoic acid borate, Tetra-substituted phosphonium / tetra-substituted borate such as tetraphenylphosphonium / tetranaphthoyloxyborate, tetraphenylphosphonium / tetranaphthyloxyborate, etc., and these may be used alone or in combination. There.

The cyclic phosphazene compound used in the present invention may be any compound having a cyclic phosphazene structure in the compound, for example, a compound having a structure represented by the formula (1) and the like, which acts as a flame retardant. I do. The flame retarding mechanism of the phosphazene compound has the effect of promoting carbonization by the contained phosphorus, that is, the effect of protecting the surface of the cured product and blocking oxygen by forming a nonflammable carbonized layer on the surface of the cured product. This is because nitrogen gas is generated at the time of thermal decomposition by the nitrogen contained, and oxygen is shut off even in the gas phase. The phosphazene compound can impart high flame retardancy due to the flame retardant effect working in both the solid phase and the gas phase.

Embedded image (In the formula, n represents an integer of 3 to 7, R represents the same or different organic groups.) In the formula (1), R represents an alkyl group,
An alkenyl group, an alkoxy group, an aryl group, an aryloxy group and the like are common, and N, S, O, and F atoms are represented by an amino group, a mercapto group, a hydroxy group, and a fluoroalkyl group. Etc. may be contained. These cyclic phosphazene compounds may be used alone or as a mixture. Further, it is more preferable that the main component be a trimer 6-membered ring. As the cyclic phosphazene compound represented by the formula (1), specifically, for example, hexapropylcyclotriphosphazene, tetraethoxydipropoxycyclotriphosphazene, hexaphenoxycyclotriphosphazene, hexaanilinocyclotriphosphazene, hexakis (3- Mercaptopropyl)
Cyclotriphosphazene, hexakis (heptafluoropropyloxy) cyclotriphosphazene and the like are mentioned as examples. As R in the formula (1), an aryloxy group is preferable from the viewpoint of heat resistance and moisture resistance. From the viewpoint of compatibility with the epoxy resin and fluidity of the epoxy resin composition, among 2n Rs, More preferably, at least n are phenoxy groups.

Further, as an example of another cyclic phosphazene compound, a compound in which one cyclic phosphazene is bonded to another cyclic phosphazene via 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 formula (1) is bonded to a part of R of another cyclic phosphazene via another organic group or R may be used. The other organic group of may be not only a single group but also a group combined with another group. For example, a compound having a phosphazene group at both terminals of an organic group may be used. As another organic group bonding these cyclic phosphazenes to each other, for example, 1,
Organic groups such as 6-dioxyhexane, etc. in which a hydrogen atom has been removed from the hydroxyl group of a diol compound, or 2 such as hydroquinone, 4,4′-biphenol, bisphenol F, etc.
A group obtained by removing a hydrogen atom from a dihydroxy compound such as a functional phenol compound can be preferably used.

The amount of the cyclic phosphazene compound of the present invention is preferably 0.01 to 10% by weight, more preferably 0.1 to 5% by weight, based on the whole epoxy resin composition.
If it is less than 0.01% by weight, the flame retardancy is insufficient, and if it exceeds 10% by weight, the curability, heat resistance and strength are reduced, and the moisture absorption is undesirably increased.

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 as needed, but the stability of the electrical characteristics of the semiconductor device at a high temperature of 150 to 200 ° C. In required applications, bromine atoms and antimony atoms are each present in the total epoxy resin composition at 0.0%.
It is preferably 1% by weight or less, and more preferably not completely contained. If either the bromine atom or the antimony atom exceeds 0.01% by weight, the resistance value of the semiconductor device increases with time when left at high temperature, and eventually a failure occurs in which the gold wire of the semiconductor device is disconnected. there's a possibility that. Further, from the viewpoint of environmental protection, it is more preferable that each of the epoxy resin compositions contains 0.01% by weight or less of bromine atoms and antimony atoms in the total epoxy resin composition, and contains as little as possible. The content of bromine atoms can be measured by elemental analysis such as fluorescent X-ray spectroscopy and ion chromatography. The content of antimony atoms can be measured by elemental analysis such as atomic absorption analysis, emission analysis, fluorescent X-ray spectroscopy, and ion chromatography. In the epoxy resin composition of the present invention, a low stress agent represented by a polysiloxane compound, a coupling agent, a coloring agent represented by carbon black, and the like can be appropriately compounded. The epoxy resin composition of the present invention is obtained by mixing the components (A) to (E) and other additives at room temperature using a mixer, kneading with a kneader such as a roll or an extruder, and cooling and pulverizing. Obtained. Using the epoxy resin composition of the present invention, to seal electronic components such as semiconductor elements, and to manufacture a semiconductor device, transfer molding, compression molding, injection molding and other conventional molding methods such as curing molding Good. Semiconductor devices to which the epoxy resin composition of the present invention is applied include QFP, SOP, TSOP, BG
A: There is no particular limitation.

[0014]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. The mixing unit is parts by weight. Example 1 Orthocresol novolak type epoxy resin (softening point: 65 ° C., epoxy equivalent: 210 g / eq) 13.6 parts by weight Vacuum distillate of residual oil after catalytic cracking of crude oil (average molecular weight 275 by vapor pressure permeation method, ASTM D) Modified phenolic resin obtained by polycondensing paraformaldehyde and phenol in the presence of toluenesulfonic acid (softening point 85 ° C, hydroxyl equivalent 175 g / eq, 150 11.4 parts by weight fused spherical silica (average particle size: 15 μm) 71.50 parts by weight 1,8-diazabicyclo (5,4,0) undecene- 7 (hereinafter referred to as DBU) 0.35 part by weight Cyclic phosphazene compound 1 represented by the formula (2) 1 2.25 parts by weight

Embedded image γ-glycidoxypropyltrimethoxysilane 0.4 parts by weight Carbon black 0.2 parts by weight Carnauba wax 0.3 parts by weight was mixed at room temperature using a mixer, kneaded using a biaxial roll, and cooled. It was pulverized to obtain an epoxy resin composition. The obtained epoxy resin composition was evaluated by the following method. Table 1 shows the results.

Evaluation method: Spiral flow: Using a mold for measuring spiral flow according to EMMI-1-66, using a mold temperature of 175
C., an injection pressure of 6.8 MPa, and a curing time of 2 minutes.
The unit is cm. Curing torque: Using a curastometer (JSR Curastometer IVPS, manufactured by Orientec Co., Ltd.), an amplitude angle of 1 degree, a mold temperature of 175 ° C, and a torque 90 seconds after the start of heating were determined. The torque in the curast meter is a parameter of curability, and the larger the numerical value, the better the curability. The unit is N · m. -Flame retardancy: mold temperature 1 using transfer molding machine
75 ° C, injection pressure 7.4 MPa, curing time 2 minutes, length 1
A test piece having a size of 27 mm, a width of 12.7 mm, a thickness of 3.2 mm, or a thickness of 1.6 mm was molded and subjected to a flame retardancy test according to UL-94. Solder stress resistance: Using a transfer molding machine, mold temperature 175 ° C, injection pressure 9.8M
80pQFP (Package size 14 × 20 × 2.7mm, chip size 7.5 × 7.5)
mm). Eight packages that were post-cured at 175 ° C for 8 hours were subjected to 85 ° C and 65% relative humidity.
After 168 hours of treatment in an environment described above, IR reflow treatment (260 ° C.) was performed. The presence or absence of internal peeling and cracks after the treatment was observed using 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. High-temperature storage characteristics: Using a transfer molding machine, a mold temperature of 175 ° C., an injection pressure of 9.8 MPa, and a curing time of 2 minutes, 16 pSOP (package size 7.2 × 11.5 ×
A simulated device having a size of 1.95 mm and a chip size of 3.0 × 3.5 mm was wired with a gold wire having a diameter of 25 μm). Fifteen packages which were post-cured at 175 ° C. for 8 hours were processed in a thermostat at 185 ° C., and the resistance value between pins was measured at regular intervals. The constant-temperature bath processing time in which the number of packages whose resistance value increased by 10% from the initial resistance value became 8 or more out of 15 was indicated as high-temperature storage characteristics. If this time is long, it indicates that the stability at high temperatures is excellent. The unit is hr. -Content of bromine atom and antimony atom: pressure 5.9Mp
The sample was compression-molded to a diameter of 40 mm and a thickness of 5 to 7 mm by a, and the content of bromine atoms and antimony atoms in all the epoxy resin compositions was quantified using a fluorescent X-ray analyzer. The unit is% by weight.

Examples 2 to 4 and Comparative Examples 1 to 4 Epoxy resin compositions were prepared in the same manner as in Example 1 and blended according to the formulation shown in Table 1, and evaluated in the same manner as in Example 1.
Table 1 shows the results. In Example 3, the crystalline epoxy resin (4,4'-bis (2,3-epoxypropoxy)-
3,3 ′, 5,5′-tetramethylbiphenyl is a main component. Melting point: 106 ° C, epoxy equivalent: 200 g / eq)
Was used. In Example 4, the cyclic phosphazene compound 2 represented by the formula (3) was used.

Embedded image

In Comparative Examples 1 and 4, a phenol novolak resin (softening point 90 ° C., hydroxyl equivalent 103 g / eq) was used. In Comparative Example 4, a brominated phenol novolak type epoxy resin (softening point: 84 ° C., epoxy equivalent: 285 g / e)
q, bromine atom content: 35% by weight).

[Table 1]

[0018]

According to the present invention, an epoxy resin composition for semiconductor encapsulation which does not contain a bromine compound and an antimony compound and has excellent moldability can be obtained. Excellent high-temperature storage characteristics and flame retardancy.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C08L 63/00 C08L 63/00 C H01L 23/29 H01L 23/30 R 23/31 F term (reference) 4J002 CC07X CD02W CD04W CD05W CD06W DA118 DE136 DE146 DJ016 DJ036 DJ046 EW157 FD016 FD137 GQ05 4J033 GA08 HA03 HB06 4J036 AA01 AC01 AC02 AC05 AD07 AD08 AF06 DB06 FA01 FA02 FA05 FA06 FA12 FB08 JA07 4M109 AA01 BA01 CA21 CA22 EB02 EB03 EB03 EB02 EB02 EB03 EB03 EB03 EB02 EB03

Claims (8)

[Claims] (A) an epoxy resin, (B) a modified phenol resin obtained by polycondensing a petroleum heavy oil or pitches, a formaldehyde polymer and a phenol in the presence of an acid catalyst, (C) An epoxy resin composition for encapsulating a semiconductor, comprising an inorganic filler, (D) a curing accelerator, and (E) a cyclic phosphazene compound as essential components. 2. A modified phenol resin obtained by polycondensing a heavy petroleum oil or pitches, a formaldehyde polymer and a phenol in the presence of an acid catalyst has a melt viscosity at 150 ° C. of 5 to 30 Pa · s. The epoxy resin composition for semiconductor encapsulation according to claim 1, which is s. 3. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the phosphazene compound is a cyclic phosphazene compound. 4. The epoxy resin composition for semiconductor encapsulation according to claim 3, wherein the cyclic phosphazene compound is a cyclic phosphazene compound represented by the formula (1). Embedded image (In the formula, n represents an integer of 3 to 7, and R represents the same or different organic groups.) 5. The epoxy resin composition for semiconductor encapsulation according to claim 4, wherein at least n out of 2n Rs of the cyclic phosphazene compound represented by the formula (1) are phenoxy groups. 6. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the inorganic filler accounts for 65 to 85% by weight of the total epoxy resin composition. 7. The total amount of bromine atoms and antimony atoms contained in the total epoxy resin composition is 0.01% by weight.
The epoxy resin composition for semiconductor encapsulation according to claim 1, 2, 3, 4, 5, or 6, wherein 8. A semiconductor device comprising a semiconductor element encapsulated with the epoxy resin composition according to claim 1.