JP2002249542A - Sealing epoxy resin composition and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealing epoxy resin composition having good reflow resistance and excellent anti-block properties by lowering the viscosity while maintaining the high melting point, and excellent moldability such as curability and flowability. SOLUTION: The sealing epoxy resin composition comprises an epoxy resin component, a curing agent, and a filler. The epoxy resin component contains at least a mixed molten resin of an epoxy resin to be represented by structural formula (A) (wherein G is a glycidyl group; and R is any one of a hydrogen atom, a halogen atom and a 1-6C hydrocarbon group) with an o-cresol novolak epoxy resin. The content of the epoxy resin to be represented by structural formula (A) in this mixed molten resin is 70-80 mass% and that of the o-cresol novolak epoxy resin is 20-30 mass%.

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 encapsulation and a semiconductor device encapsulated with the encapsulating resin composition. The present invention relates to a sealing epoxy resin composition that can be suitably used for sealing electronic components, semiconductor devices, and the like, and a semiconductor device sealed with the sealing epoxy resin composition.

[0002]

2. Description of the Related Art Conventionally, as a method of sealing electric, electronic parts such as diodes, transistors, and integrated circuits, and semiconductor devices, for example, a sealing method using epoxy resin or silicone resin, glass, metal, ceramics, or the like is used. The hermetic sealing method has been adopted, but in recent years, resin sealing by low-pressure transfer molding using an epoxy resin, which has high reliability and improved mass productivity and cost merit, is becoming the mainstream.

In the encapsulation method using this epoxy resin, a molding material comprising a composition comprising an o-cresol novolak type epoxy resin as an epoxy resin component and a phenol novolak type resin as a curing agent component is most commonly used. ing.

[0004]

However, in recent years,
As electronic components have become smaller and thinner, epoxy resin compositions for encapsulation with lower viscosity have been desired. In recent years, the mounting method of electronic components on a substrate has been shifting from the pin mounting method to the surface mounting method. However, in this surface mounting method, the entire electronic component package is heated to the melting temperature of solder during mounting. In addition, the occurrence of package cracks due to thermal shock or moisture expansion of the package has become a major problem. Further, in recent years, high integration of semiconductor elements, increase in element size, and miniaturization of wiring width have been rapidly progressing, and thus the problem of package cracking has become more serious.

As a method for preventing the occurrence of such package cracks, there is a method of increasing the strength of a sealing material and reducing moisture absorption by increasing the filling of silica into an epoxy resin composition for sealing. In an epoxy resin composition using an o-cresol novolac type epoxy resin, there is a limit to a decrease in viscosity, and when a filler is added in an amount of 78 to 80% by mass, the viscosity of the resin sharply increases. Problems such as displacement of the element and cutting of the bonding wire occur.

The use of a biphenyl-type epoxy resin or a dicyclopentadiene-type epoxy resin makes it possible to easily reduce the viscosity of an epoxy resin composition for encapsulation. However, such a resin is expensive, and such a resin is expensive. A resin composition prepared using a suitable resin is likely to generate voids during molding due to a decrease in melting point with a decrease in viscosity,
Problems such as blocking of the material occur. In addition, when these resins are used, the reactivity of the resin composition at the time of curing and molding is remarkably reduced, which causes a problem in the releasability and releasability during molding.

The present invention has been made in view of the above points. By reducing the melt viscosity while maintaining a high melting point, the present invention has good reflow resistance and excellent blocking resistance, and has excellent curability and fluidity. It is an object of the present invention to provide a sealing epoxy resin composition excellent in moldability such as moldability, and a semiconductor device sealed using the sealing epoxy resin composition.

[0008]

According to the first aspect of the present invention, there is provided an epoxy resin composition for encapsulation comprising an epoxy resin component, a curing agent and a filler. It contains a mixed molten resin of at least an epoxy resin represented by the following structural formula (A) and an o-cresol novolac type epoxy resin, and the content of the epoxy resin represented by the following structural formula (A) in the mixed molten resin is 70 to 80% by mass, and the content of the o-cresol novolac type epoxy resin is 20 to 30% by mass.

[0009]

Embedded image

A second aspect of the present invention is characterized in that, in the first aspect, silica is contained as a filler.

The invention of claim 3 is characterized in that, in claim 1 or 2, the content of the filler is 80 to 93% by mass.

Further, the invention of claim 4 provides the invention according to claims 1 to 3
In any one of the above, as the epoxy resin component, a composition comprising at least one of a dicyclopentadiene-type epoxy resin and a biphenyl-type epoxy resin is blended in an amount of 20 to 70% by mass based on the total amount of the epoxy resin component. It is a feature.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, a phenol aralkyl-based resin is blended as a curing agent in an amount of 20 to 100% by mass based on the total amount of the curing agent. Things.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects, morpholine is contained in an amount of 0.01 to 1% by mass.
It is characterized by being compounded.

A semiconductor device according to a seventh aspect of the present invention is characterized by being sealed with the epoxy resin composition for sealing according to any one of the first to sixth aspects.

[0016]

Embodiments of the present invention will be described below.

The epoxy resin component essentially comprises a mixed molten resin of the epoxy resin represented by the above structural formula (A) and an o-cresol novolak type epoxy resin. The content of the epoxy resin represented by the structural formula (A) is 70 to 80% by mass.
And the content of the o-cresol novolak type epoxy resin is 20 to 30% by mass.

The melting point of such a mixed molten resin is 119 ° C.
Since the degree is high, the melting point of the epoxy resin composition can be maintained high, and the reactivity of the epoxy resin composition can be maintained high. Furthermore, the melt viscosity of the epoxy resin composition can be reduced, and a low melt viscosity can be maintained even when the filling amount of the filler is increased.

As the epoxy resin component, in addition to the above-mentioned mixed molten resin, those conventionally used as epoxy resin components of epoxy resin compositions for sealing can be used in combination. Type epoxy resin, o-cresol novolak type epoxy resin, dicyclopentadiene type epoxy resin, bisphenol type epoxy resin, bromide-containing epoxy resin, epoxy resin having a naphthalene ring, and the like.

The content of the above-mentioned mixed molten resin in the total epoxy resin component is preferably from 30 to 100% by mass. If the amount is less than this range, the blocking resistance is sufficiently improved. May not be possible.

Further, at least one of a dicyclopentadiene-type epoxy resin and a biphenyl-type epoxy resin is blended as the epoxy resin component, and the total amount of the dicyclopentadiene-type epoxy resin and the biphenyl-type epoxy resin is blended. However, when the content is set to 20 to 70% by mass with respect to the total amount of the epoxy resin component, the hygroscopicity of the sealing resin can be further reduced, and the adhesion can be further improved. Here, the melting points of the dicyclopentadiene type epoxy resin and the biphenyl type epoxy resin are low, but the melting point of the epoxy resin composition is maintained at a high temperature by blending the above-mentioned mixed molten resin. At this time, if the total amount of the dicyclopentadiene-type epoxy resin and the biphenyl-type epoxy resin is less than the above range, the effect of improving the reflow resistance may not be sufficiently obtained. If it exceeds, the effect of improving the blocking resistance may not be sufficiently obtained.

The total amount of the above epoxy resin components is 6 to 1 with respect to the total amount of the epoxy resin composition for sealing.
It is preferable to be in the range of 9% by mass.

As the curing agent, various phenol compounds and naphthol compounds such as a phenol aralkyl resin, a phenol novolak resin, a cresol novolak resin, a compound having a terpene skeleton, a compound having a dicyclo skeleton, and a naphthol aralkyl resin can be used. it can. In particular, when a phenol aralkyl-based resin such as a phenol aralkyl resin or a naphthol aralkyl resin is blended in an amount of 20 to 100% by mass based on the total amount of the curing agent, it is possible to further reduce the hygroscopicity of the sealing resin and the bending elasticity when heated. And reflow resistance can be improved.

Such a curing agent has an equivalent ratio of 0.5 to the epoxy resin component in the epoxy resin composition for sealing.
~ 1.5, preferably 0.8 ~ 1.2.

As the curing accelerator, organic phosphines such as triphenylphosphine, tertiary amines such as diazabicycloundecene, imidazoles such as 2-trimethylimidazole and 2-phenylimidazole can be used. .

As the filler, fused silica, crystalline silica, zircon silicate, alumina, calcium carbonate, quartz powder, zircon oxide, talc, clay, barium sulfate, asbestos powder and the like can be used. It is preferable to use silica such as silica. Such a filler is preferably contained in the range of 80 to 93% by mass with respect to the total amount of the epoxy resin composition for sealing. The reflow resistance can be further improved. At this time, if the compounding amount of the filler is less than the above range, reflow resistance may not be sufficiently improved, and if the compounding amount exceeds the above range, the molding of the epoxy resin composition at the time of molding may be performed. Fluidity may be reduced.

The release property can be improved by adding a release agent to the epoxy resin composition for sealing. Carnauba wax, stearic acid,
Montanic acid, carboxyl group-containing polyolefin, or the like can be used, and the amount thereof is preferably 0.1 to 1.0% by mass based on the total amount of the epoxy resin composition for sealing.

It is preferable that morpholine be incorporated in an amount of 0.01 to 1% by mass based on the total amount of the epoxy resin composition for encapsulation. In this case, the adhesion of the encapsulation resin is further improved, and the reflow resistance is improved. It is possible to further improve the performance. If the amount of the morpholine is less than the above range, sufficient adhesion between the sealing resin and the lead frame or the like may not be obtained. If the amount exceeds this range, the reactivity (curing property) of the epoxy resin composition may be reduced. ) May be reduced.

Further, as the ion scavenger, a compound represented by the following chemical formula (B) can be blended. In such a case, the impurity ions in the sealing epoxy resin composition can be reduced, and Moisture resistance reliability can be further improved. The compounding amount of the ion scavenger is preferably 0.1 to 1.0% by mass based on the total amount of the epoxy resin composition for sealing. It is difficult to reduce impurity ions, and if it exceeds this range, the curing properties may be adversely affected. During _{Sb · Si v · Bi w ·} O x · (OH) y · (NO 3) z · nH 2 O (B) ( formula (B), v = 0~0.3, w = 0.5~
2.0, x = 3.0-5.0, y = 0.4-2.0, z
= 0.1 to 0.5, n = 1 to 2) Also, if necessary, silane coupling agents such as γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, flame retardants, coloring agents Also, a silicone flexible agent or the like can be added.

In preparing the epoxy resin composition for encapsulation of the present invention, a mixture of the above-mentioned components to be prepared in a desired ratio is uniformly mixed with a mixer, a blender or the like, and then kneaded or heated. The mixture can be heated and kneaded by a roll or the like, then solidified by cooling, and pulverized to obtain a granular epoxy resin composition for sealing.

The epoxy resin composition for encapsulation thus prepared can achieve a low viscosity while maintaining a high melting point, and can suppress generation of voids and blocking during molding. It has high reactivity and good curability, and therefore has high moldability.

Further, even if the filler is highly filled, a low viscosity can be maintained, and while maintaining the moldability, the molded body is provided with moisture absorption resistance and a linear expansion coefficient is reduced, thereby improving reflow resistance. Can be improved.

An example of a method for manufacturing a semiconductor device using a cured molded article of the epoxy resin composition for sealing as a sealing resin will be described. For example, first, a semiconductor element is mounted on a lead frame made of metal such as 42 alloy or copper. Die bonding. Then A
The lead frame and the semiconductor element are connected by a wire bonding method using a thin wire such as u. Next, a sealing resin is molded by transfer molding or the like using the epoxy resin composition of the present invention to seal the semiconductor element and the wire.

[0034]

Examples (Examples 1 to 6 and Comparative Examples 1 to 3) For each of the Examples and Comparative Examples, the respective blending materials shown in Table 1 were blended, mixed for 30 minutes with a blender, and homogenized. The mixture was melted and extruded with a heated kneader, extruded, cooled, pulverized with a metal mesh having a mesh size of 3 mm, and classified with a 10-mesh sieve to obtain a granular epoxy resin composition for sealing.

Here, among the components in the table, the mixed molten resin contains the epoxy resin represented by the structural formula (A) in the range of 70 to 80% by mass, and the o-cresol novolac type epoxy resin has the content of 20 to 30% by mass. "ZX1598A" (epoxy equivalent: 188; melting point: 119 ° C .; melt viscosity: 0.04 Pa · s) manufactured by Toto Kasei Co., Ltd. ESCN-195XL "(epoxy equivalent 195;
Melting point 60-70 ° C .; melt viscosity 2-3 Pa · s), and the biphenyl type epoxy resin is “YX4000H” manufactured by Yuka Shell Epoxy Co., Ltd. (epoxy equivalent 195; melting point 1).
The melting point is lowered at the time of melting because the crystalline resin is a crystalline resin; the melt viscosity is 0.2 Pa · s), and the dicyclopentadiene type epoxy resin is “HP7200” (epoxy equivalent 264, manufactured by Dainippon Ink and Chemicals, Inc.). Melting point 57-
Phenol novolak resin is "PSM6200OH" (OH equivalent 10
5), phenol aralkyl resin is “HE100C15” (OH equivalent 105) manufactured by Sumikin Chemical Co., Ltd.
The brominated epoxy resin is "E" manufactured by Sumitomo Chemical Co., Ltd.
SB400 "(epoxy equivalent 400) is shown.

(Evaluation Test) O Reflow Resistance Test A TEG (testments group) was die-bonded as a semiconductor element for evaluation on a metal lead frame, and a sealing epoxy prepared in each of Examples and Comparative Examples. Using a resin composition, mold temperature 175
After transfer molding at 175 ° C for 175 seconds, the resin was sealed by heating after heating at 175 ° C for 6 hours, followed by resin sealing.
128 pin QFP (qua) for evaluation of mx 2.4 mm
d flat package) was prepared. As the lead frame, using two types of 42 alloy and copper,
An evaluation QFP was prepared for each.

The QFP for evaluation was inspected for the presence or absence of peeling by observing the die pad surface with an ultrasonic probe, and then subjected to a moisture absorption treatment at 85 ° C./60% RH for 168 hours. 240-245 ° C in a reflow furnace
For 10 seconds. Furthermore, the die pad surface of the QFP for evaluation after this treatment is observed with an ultrasonic probe to confirm the presence or absence of peeling.
Was cut, and the section was observed with a stereoscopic microscope to confirm the presence or absence of cracks.

For each of the examples and comparative examples, evaluation was made based on the number of samples in which the peeling of the die pad surface and the occurrence of cracks occurred were compared with the number of samples subjected to the test. In Table 1,
The number of samples subjected to the test is shown for the denominator, and the number of samples for which a defect occurred in the numerator.

Evaluation of Void Generation The inside of the sealing resin was observed with an ultrasonic probe for the evaluation QFP used in the reflow resistance test, and the number of generated voids was confirmed. At this time, the voids in 10 samples were observed for each of the one using the 42 alloy lead frame and the one using the copper lead frame, and the total number of voids having a diameter of 1 mm or more in all the samples was calculated. Was evaluated.

Evaluation of moldability (curability, fluidity) Evaluation of curability The epoxy resin composition for sealing obtained in each of the examples and comparative examples was measured at 170 ° C. for 6 times using a curastometer.
The torque of the curast meter when heated for 0 seconds was measured.

Evaluation of Flowability The epoxy resin compositions for sealing obtained in each of the examples and comparative examples were subjected to a spiral flow test, and the flowability was evaluated based on the length of the spiral flow. The spiral flow test was performed in accordance with ASPM-D 3123, and the mold temperature was 170 ° C., and the supply pressure was 6.86 MPa (70 kg / cm).
The procedure was performed under ² ).

○ Evaluation of blocking property The epoxy resin composition for sealing obtained in each of Examples and Comparative Examples was added to a 50 g sample at 1.96 k per unit area.
25 ° C. under a load of Pa (20 g / cm ² )
For 24 hours. The epoxy resin composition for sealing after this treatment was sieved with a 4 mm sieve, and the weight of the sample remaining on the sieve was measured.

Then, the blocking rate was evaluated based on the weight percentage of the sample remaining on the sieve with respect to the sample subjected to the test.

Table 1 shows the above results.

[0045]

[Table 1]

Comparative Example 1 having poor reflow resistance and low fluidity
In contrast, Comparative Examples 2 and 3 having poor curing properties and blocking properties and a large amount of voids,
With respect to reflow resistance, curability, fluidity, blocking properties, and the number of voids generated, all favorable evaluation results were obtained, and it was confirmed that the composition had excellent moldability.

[0047]

As described above, the epoxy resin composition for encapsulation according to claim 1 of the present invention is an epoxy resin composition for encapsulation containing an epoxy resin component, a curing agent and a filler.
As an epoxy resin component, a mixed molten resin of at least the epoxy resin represented by the structural formula (A) and an o-cresol novolak type epoxy resin is contained, and the epoxy resin represented by the structural formula (A) is contained in the mixed molten resin. Since the amount is 70 to 80% by mass and the content of the o-cresol novolak type epoxy resin is 20 to 30% by mass, the epoxy resin composition for sealing prepared in this manner maintains a high melting point. , Which can achieve low viscosity, suppress generation of voids and blocking during molding, and have high reactivity and good curability, and therefore have high moldability. And also
It is possible to maintain a low viscosity even when the filler is highly filled, and to maintain the moldability, to provide the molded article with moisture absorption resistance and to reduce the linear expansion coefficient to improve reflow resistance. You can do it.

According to a second aspect of the present invention, in the first aspect, since silica is contained as a filler, the moisture absorption resistance of the sealing resin is improved, and the linear expansion coefficient is reduced to suppress the generation of internal stress. However, the reflow resistance can be further improved.

According to a third aspect of the present invention, in the first or second aspect, the content of the filler is set to 80 to 93% by mass. It is possible to improve the hygroscopicity, reduce the linear expansion coefficient, suppress the generation of internal stress, and further improve the reflow resistance.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the epoxy resin component comprises at least one of a dicyclopentadiene type epoxy resin and a biphenyl type epoxy resin. 20-70% by mass based on the total amount of the components, further reducing the hygroscopicity of the sealing resin and further improving the adhesion to the die pad surface when the semiconductor device is sealed with the sealing resin. And the reflow resistance can be further improved.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, a phenol aralkyl-based resin is blended as a curing agent in an amount of 20 to 100% by mass based on the total amount of the curing agent. The properties and elasticity can be further reduced, and the reflow resistance can be further improved.

The invention according to claim 6 is the method according to any one of claims 1 to 5, wherein morpholine is contained in an amount of 0.01 to 1% by mass.
The compounding can further improve the adhesion to the die pad surface when the semiconductor device is sealed with the sealing resin, and can further improve the reflow resistance.

Continued on the front page F-term (reference) 4J036 AA01 AA04 AA05 AA06 AB01 AB09 AD01 AD07 AF06 AF08 AJ08 DA04 DA05 DB06 DB11 DC17 DC18 DC38 DC41 DC46 DC48 DD07 FA03 FA05 FA06 FA12 FB08 FB12 JA07 4M109 AA01 EA02 EB03 EB09

Claims (7)

[Claims] 1. An epoxy resin composition for sealing comprising an epoxy resin component, a curing agent and a filler, wherein at least an epoxy resin represented by the following structural formula (A) as an epoxy resin component, and an o-cresol novolac type epoxy resin. And the content of the epoxy resin represented by the following structural formula (A) in the mixed molten resin is 70 to 80.
An epoxy resin composition for sealing, wherein the content of the o-cresol novolak type epoxy resin is 20 to 30% by mass. Embedded image 2. The epoxy resin composition for sealing according to claim 1, comprising silica as a filler. 3. The sealing epoxy resin composition according to claim 1, wherein the content of the filler is 80 to 93% by mass. 4. An epoxy resin component comprising at least one of a dicyclopentadiene type epoxy resin and a biphenyl type epoxy resin in an amount of 20 to 70% by mass based on the total amount of the epoxy resin component. The epoxy resin composition for sealing according to any one of claims 1 to 3, wherein: 5. The epoxy resin for sealing according to claim 1, wherein a phenol aralkyl-based resin is blended as a curing agent in an amount of 20 to 100% by mass based on the total amount of the curing agent. Composition. 6. The epoxy resin composition for sealing according to claim 1, wherein the composition comprises 0.01 to 1% by mass of morpholine. 7. A semiconductor device which is sealed with the epoxy resin composition for sealing according to claim 1.