JPH0841168A - Liquid epoxy resin composition and semiconductor device - Google Patents

Abstract

PURPOSE:To obtain an epoxy resin compsn. which has a low viscosity and a good handleability, is suitable for forming a sealing resin layer by spot seafling, and gives a cured item free from bleeding and excellent in low-stress properties. CONSTITUTION:This compsn. is prepd. by compounding an epoxy-modified silicone oil having an epoxy equivalent of 260 or lower, a phenolic curative, a cure accelerator, and a filler. The oil pref. has a viscosity at 25 deg.C of 300 P or lower. The curative is a phenol novolak resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid epoxy resin composition used for bare chip encapsulation, such as COB,
The present invention relates to a liquid epoxy resin composition used for applications such as PGA, PLCC, BGA and TAB, and particularly for a large area semiconductor element, and a semiconductor device using the same.

[0002]

2. Description of the Related Art Epoxy resin compositions have excellent electrical performance and adhesive strength, and are therefore used in various applications in the electric and electronic fields. 2. Description of the Related Art In recent years, in the field of electronics, high integration has progressed, and chips such as gate arrays and other special-purpose integrated circuits (ASICs) and chips typified by memories have been significantly increased in size. These chips are chip-on-board (C
OB), Pin Grid Array (PGA), Plastic Leaded Chip Carrier (PLCC), Ball Grid Array (BGA), Tape Automated Bonding (TAB), etc. Is often done.
The liquid epoxy resin composition for semiconductor encapsulation is required to have properties such as low viscosity, low expansion, low impurity ions, and high adhesion. Also, characteristics such as high adhesion are required. That is, as the size of the chip increases, stress based on the difference in thermal expansion between the substrate and the chip occurs at the interface between the chip and the resin. However, there is a problem that it leads to defects such as peeling of the interface of the resin and increase of the warp of the resin.

When curing the liquid epoxy resin composition, various curing agents such as acid anhydrides, amines, phenols, or imidazoles are used, and it is known that the performance of the cured material varies greatly depending on the type of the curing agent. The curing agent is used properly depending on the application. For example, in the use of adhesives and laminates, amine-based curing agents are used because adhesion is the most important, and in casting applications, acid anhydrides are used from the viewpoint of electrical performance and low viscosity. Phenolic curing agents are used for sealing materials from the viewpoint of water resistance.

Conventionally, amines and acid anhydrides have been known as curing agents for liquid epoxy resin compositions such as solventless adhesives, sealing materials for electric and electronic parts, and coatings. When a phenol-based curing agent is used, a phenol novolac resin is generally used, and its molecular weight is large and the amount of the above-mentioned phenol novolac resin curing agent added to the epoxy resin is 50 PHR or more, which is large. In the case of a liquid epoxy resin composition using a liquid bisphenol A type epoxy resin, the viscosity becomes so high that it cannot be put to practical use. However, in terms of the balance of physical properties such as adhesiveness, water resistance, and electrical performance, the phenolic curing agent is the most excellent curing agent. That is, since it is difficult to liquefy, phenolic curing agents can generally be used only for solid molding materials. Amine-based and acid anhydride-based curing agents are easy to liquefy, but have the following problems. That is, when an amine-based curing agent is used, the hygroscopicity is high because a tertiary amine structure exists in the crosslinked structure of the cured product. When an acid anhydride-based curing agent is used, long-term water resistance is poor because the ester structure in the crosslinked structure of the cured product is easily chemically hydrolyzed, and the acid anhydride group of the curing agent and the epoxy resin The cured product is inferior in adhesiveness because the alcoholic hydroxyl group that contributes to adhesion is less likely to be by-produced by the reaction with the epoxy group.

Since recent electronic parts tend to be higher in density and thinner, a bare chip is mounted from a conventional transfer molded package and sealed with a liquid sealing material.
So-called chip-on-board (COB) and TAB (Tap)
e Automated Bonding) is being replaced. As a conventional liquid encapsulating material, an epoxy resin composition using an amine-based or acid anhydride-based curing agent is predominant because of its limited viscosity. However, the liquid encapsulant composed of the epoxy resin composition using the amine-based or acid anhydride-based curing agent is more than the transfer molding material composed of the epoxy resin composition using the phenol novolac resin curing agent described above. Poor overall reliability. Therefore, it is strongly desired to improve the reliability of the liquid sealing material. Therefore, in order to compensate for the drawback of high viscosity of the epoxy resin composition using a phenolic curing agent, the use of a solvent,
Although the handling of the liquid encapsulating material has been facilitated by using it together with an amine-based curing agent or an acid anhydride-based curing agent, the liquid sealing material has not yet reached a satisfactory stage.

[0006] Further, in order to impart a low stress, incompatible silicone modification is performed. That is, in the silicone modification method that is compatible with the epoxy resin, the effect of lowering the elastic modulus is small and the low stress property is small. However, in the liquid encapsulant using the incompatible silicone modification method, the viscosity tends to increase, and in addition, the so-called bleed phenomenon occurs in which the incompatible silicone component floats on the surface during resin curing. There was a drawback.

On the other hand, in some applications such as a plastic pin grid array (PPGA), a method of encapsulating a semiconductor chip using silicone gel is also known, and the silicone gel is a very soft gel-like material. Therefore, the problem due to stress does not occur. However,
In this method, since the strength is low, it is not possible to mechanically protect the semiconductor chip, which is one of the original purposes of the encapsulation, so a metal lid or the like is required, and there is also a drawback that leakage during moisture absorption is likely to occur. It was

Attempts have been made to seal with a silicone-based resin, but there was the problem of poor adhesion and moisture resistance.

Further, in the semiconductor device for TAB, not only a low stress but also a flexible material which is not peeled off from the polyimide film due to the deformation of the TAB film is required.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above facts, and an object thereof is to form a resin sealing layer by spot sealing with low viscosity and good handleability. A liquid epoxy resin composition which is suitable for use as a liquid epoxy resin composition and which does not cause bleeding and can give a cured product excellent in low stress, and a semiconductor device having improved performance using the same.

[0011]

The liquid epoxy resin composition according to claim 1 of the present invention contains an epoxy-modified silicone oil having an epoxy equivalent of 260 or less, a phenolic curing agent, a curing accelerator and a filler. Is characterized by.

A liquid epoxy resin composition according to a second aspect of the present invention is characterized in that the viscosity of the epoxy-modified silicone oil is 300 centipoise or less at 25 ° C.

A liquid epoxy resin composition according to a third aspect of the present invention is characterized in that the phenolic curing agent is a phenol novolac resin.

A semiconductor device according to a fourth aspect of the present invention is characterized by being sealed with the liquid epoxy resin composition according to any one of the first to third aspects.

A semiconductor device according to a fifth aspect of the present invention is characterized in that it is sealed with the liquid epoxy resin composition to a film thickness of 0.5 mm or less.

The present invention will be described in detail below. In order to obtain a bleed-free cured product, the liquid epoxy resin composition of the present invention contains an epoxy-modified silicone oil having an epoxy equivalent of 260 or less as an essential component. Various known methods can be used for introducing an epoxy group into the silicone skeleton. For example, a glycidyl compound containing an allyl group under a metal catalyst such as platinum in a silicone oil containing a hydrosilyl group, for example, a method of hydrosilylating an allyl glycidyl ether, a silicone oil containing a vinyl group by peracid, Examples of the epoxidizing method and the like can be given. A typical epoxy-modified silicone oil obtained by the former method is a compound represented by the following general formula (hereinafter referred to as compound A).

[0017]

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In the above general formula, n is an integer of 3 or more. For example, when n = 3, the epoxy equivalent is 22
When 8 and n = 6, an epoxy-modified silicone oil having an epoxy equivalent of 201 is obtained. The above compound A is
This is an example in which an epoxy group is introduced into the pendant, but another example is an epoxy-modified silicone oil in which epoxy groups are introduced into both terminals like a compound represented by the following general formula (hereinafter referred to as compound B). is there.

[0019]

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In the case of a mixture in which m in the general formula is 1.5 on average, an epoxy-modified silicone oil having an epoxy equivalent of 237 is obtained.

When the epoxy equivalent of the above-mentioned epoxy-modified silicone oil such as compound A or compound B exceeds 260, compatibility with a curing agent or the like is not sufficiently obtained, and phase separation occurs in the cured product. Not only causes bleeding,
Since the epoxy group cannot completely react with the curing agent, it becomes a brittle cured product, which is not preferable. When the epoxy equivalent of the epoxy-modified silicone oil such as the compound A or the compound B is 260 or less, the cured product becomes a uniform layer and phase separation does not occur. It is more preferable that the epoxy equivalent of the epoxy-modified silicone oil such as the compound A or the compound B is 240 or less. Furthermore, it is desirable that the viscosity of the epoxy-modified silicone oil contained in the liquid epoxy resin composition of the present invention is 300 centipoise or less at 25 ° C. in order to have a good viscosity as a liquid sealing material. That is, when the viscosity of the epoxy-modified silicone oil exceeds 300 centipoise at 25 ° C., the viscosity of the liquid epoxy resin composition when the phenolic curing agent is dissolved increases sharply, and a filler should be added. As a result, the viscosity of the liquid epoxy resin composition increases more rapidly.

The epoxy resin used in the liquid epoxy resin composition of the present invention is an epoxy resin having two or more epoxy groups in one molecule, such as a bisphenol A type epoxy resin, a bisphenol F type epoxy resin or a fat. You may use together cyclic epoxy resin and epoxy modified silicone oil. This is because when the epoxy equivalent of the epoxy-modified silicone oil is 260 or less, the compatibility is not impaired even when the epoxy resin is used in combination.
However, from the viewpoint of viscosity and low stress, the content of epoxy-modified silicone oil is 5 relative to the total amount of epoxy resin.
It is preferably 0% by weight or more.

The liquid epoxy resin composition of the present invention contains a phenolic curing agent as a curing agent as an essential component. That is, by curing an epoxy with a phenolic curing agent, a cured product of a liquid epoxy resin composition having low moisture absorption and excellent adhesion can be obtained. As the phenol-based curing agent, any curing agent such as a phenol resin having at least two phenolic hydroxyl groups in one molecule can be used. For example, phenol novolac resin, cresol novolac resin, pyrogallol And polyfunctional phenol resins. In order to increase the crosslink density of the cured product as much as possible and obtain a cured product having toughness, it is preferable to include a phenol novolac resin among the phenol-based curing agents. The phenol novolac resin also includes allylated phenol novolac resin. Although it may be used in combination with other compound as a curing agent, for example, an acid anhydride, an aromatic amine or imidazoles, it is necessary to contain 50% by weight or more of a phenolic curing agent based on the total amount of the curing agent. From the point of, it is preferable.

The liquid epoxy resin composition of the present invention contains a curing accelerator as an essential component. Examples of the curing accelerator include tertiary amines, imidazoles, and phosphorus compounds such as triphenylphosphine, but are not particularly limited.

The liquid epoxy resin composition of the present invention contains a filler as an essential component. Examples of this filler include crystalline silica, fused silica, alumina and the like,
In order to effectively suppress the thermal expansion coefficient of the cured product with a low content, it is preferable to use fused silica. The content of the filler is preferably 20 to 85% by weight, more preferably 40 to 75% by weight based on the total amount of the liquid epoxy resin composition in order to suppress expansion and contraction with the substrate. That is, when the content of the inorganic filler exceeds 85% by weight with respect to the total amount of the liquid epoxy resin composition, the viscosity of the liquid epoxy resin composition becomes too high, and when it is less than 20% by weight, the heat Expansion coefficient becomes large.

The liquid epoxy resin composition of the present invention may be added with a reaction diluent, a flame retardant, a pigment, a dye, a coupling agent, an ion trap agent, a release agent, etc., if necessary.

By encapsulating a semiconductor device such as a COB type semiconductor device and a TAB type semiconductor device using the liquid epoxy resin composition of the present invention, a semiconductor device excellent in temperature cycle and flexibility can be obtained. In particular, when a TAB type semiconductor device is produced by using the liquid epoxy resin composition of the present invention, it is preferable to apply it with a film thickness of 0.5 mm or less. That is, when the film thickness exceeds 0.5 mm, the semiconductor device becomes thick and cannot be thinned, and the flexibility of the cured film is lowered, so that the cured film cannot follow the deformation of the TAB film. Since the liquid epoxy resin composition of the present invention uses epoxy curing with a phenol-based curing agent, it has excellent adhesiveness and reliability.
Even with a film thickness of 5 mm or less, sufficient sealing reliability can be ensured.

[0028]

Since the liquid epoxy resin composition according to the first aspect of the present invention contains the epoxy-modified silicone oil having an epoxy equivalent of 260 or less, the cured product becomes a uniform layer and phase separation does not occur. That is, when the epoxy equivalent of the epoxy-modified silicone oil exceeds 260, compatibility with a curing agent or the like cannot be sufficiently obtained, and not only causes phase separation in the cured product but causes bleeding. Since the group cannot completely react with the curing agent, it becomes a brittle cured product,
Not preferred.

In the liquid epoxy resin composition according to claim 2 of the present invention, the viscosity of the epoxy-modified silicone oil is 2
Since it is 300 centipoise or less at 5 ° C., it is desirable in that it has a good viscosity as a liquid sealing material. That is, when the viscosity of the epoxy-modified silicone oil exceeds 300 centipoise at 25 ° C., the viscosity of the liquid epoxy resin composition when the phenolic curing agent is dissolved increases sharply, and a filler should be added. As a result, the viscosity of the liquid epoxy resin composition increases more rapidly.

In the liquid epoxy resin composition according to claim 3 of the present invention, since the phenolic curing agent is a phenol novolac resin, the liquid epoxy resin composition has low moisture absorption, excellent adhesiveness, increased crosslink density and toughness. A cured product of the resin composition can be obtained.

Since the semiconductor device according to claim 4 of the present invention is sealed with the liquid epoxy resin composition according to any one of claims 1 to 3, it is excellent in temperature cycle and flexibility. .

Since the semiconductor device according to claim 5 of the present invention is sealed with the liquid epoxy resin composition to a film thickness of 0.5 mm or less, the cured film has flexibility.
The cured film can follow the deformation of the film.

[0033]

EXAMPLES The present invention will be specifically described below with reference to Examples and comparison with Comparative Examples.

(Examples 1 to 10) As the epoxy-modified silicone oil, the epoxy equivalent of 198 in which n is about 6 in the above compound A is 198, and the viscosity at 25 ° C. is 60.
Centipoise side chain epoxy-modified silicone oil (hereinafter referred to as epoxy-modified silicone A) and epoxy equivalent 194 in which n is about 0.6 in the above compound B
At 25 ° C., a viscosity of 10 centipoise at both ends epoxy-modified silicone oil (hereinafter referred to as epoxy-modified silicone B), and an epoxy equivalent of 200, an epoxy-modified silicone oil having a viscosity of 250 centipoise at 25 ° C. (hereinafter, epoxy-modified) Silicone C) and an epoxy-modified silicone oil having an epoxy equivalent of 220 and a viscosity of 800 centipoise at 25 ° C. (hereinafter referred to as epoxy-modified silicone D) were used. As the epoxy resin, a bisphenol A type epoxy resin having an epoxy equivalent of 175 and a viscosity at 25 ° C. of 4000 centipoise was used. As the curing agent, a phenol novolac resin, an allylated phenol novolac resin having a phenolic hydroxyl group equivalent of 120, pyrogallol, and hexahydrophthalic anhydride were used. As the curing accelerator, 1,8 diaza-bicyclo- (5,4,0) undecene-7 [DBU] octylate (SA102: manufactured by San-Apro) was used. Fused silica was used as the filler. As a colorant,
Carbon black was used.

Epoxy-modified silicone oil or bisphenol A type epoxy resin and a curing agent were added at 100 ° C. based on the amounts shown in Table 1 in parts by weight.
After being uniformly dissolved in, a curing accelerator, a filler and a colorant were blended, and mixed and kneaded for 5 minutes at 1000 rpm using a high speed stirrer to obtain a liquid epoxy resin composition.

In each of the examples, the cured product obtained by mixing the epoxy-modified silicone oil or the bisphenol A type epoxy resin with the curing agent and the curing accelerator and curing was transparent and had a uniform compatibility. .

An evaluation C in which a TEG chip having an aluminum pattern with a line width of 5 μm formed on a silicone wafer was wire-bonded to a printed circuit board using a gold line of 25 μm.
The liquid epoxy resin composition having a thickness of 1.2 mm was applied to OB and gelled at 120 ° C. for 1 hour.
A COB type semiconductor device was obtained by heat treatment at 0 ° C. for 3 hours and curing. Further, the same chip mounted on a 208-pin TAB having outer leads of 0.3 mm pitch was coated with the obtained liquid epoxy resin composition in a film thickness of 0.4 mm, and the TAB type was prepared under the same curing conditions as above. A semiconductor device is obtained.

No bleed was observed in the cured product of the liquid epoxy resin composition in any of the examples.

The viscosity of the liquid epoxy resin composition at 25 ° C. is shown in Table 1. A COB type semiconductor device was subjected to a vapor phase temperature cycle test at -55 ° C to room temperature (about 25 ° C) to 150 ° C to evaluate the disconnection of aluminum wiring of TEG and the presence or absence of peeling by ultrasonic microscope observation of the TEG surface, The results are shown in Table 1.

For the TAB type semiconductor device, in addition to the vapor phase temperature cycle test similar to the above, a bending repetition test of R = 50 mm was carried out, and shown in Table 1.

[0041]

[Table 1]

Comparative Examples 1 to 3 In Comparative Examples 1 to 3, epoxy-modified silicone oil (hereinafter referred to as epoxy-modified silicone E) having an epoxy equivalent of 300 and a viscosity of 240 centipoise at 25 ° C. was used. Others were the same as in the examples except that the components used in the examples were used in the formulations shown in parts by weight in Table 2, the epoxy resin composition, the COB type semiconductor device and the TA.
A B type semiconductor device was obtained.

The cured product obtained by mixing the epoxy-modified silicone oil of Comparative Example 1, the curing agent and the curing accelerator and curing was cloudy and non-uniform. Although bleeding of silicone oil was observed on the surface of the cured product of the liquid epoxy resin composition obtained in Comparative Example 1, bleeding was observed on the surface of the cured product of the liquid epoxy resin composition obtained in Comparative Example 3. I couldn't see it. When the bisphenol A type epoxy resin and the curing agent in Comparative Example 2 were uniformly dissolved at 100 ° C., the solution did not have fluidity at room temperature.

The same evaluation test as in the example was conducted and the results are shown in Table 2.

[0045]

[Table 2]

From the results shown in Tables 1 and 2 above, the epoxy resin compositions of Examples 1 to 10 are
Compared to Comparative Example 3, it has a low viscosity and good handleability, is suitable for forming a resin sealing layer by spot sealing, does not cause bleeding, has flexibility and adhesiveness, and has high temperature cycle reliability. It was confirmed that the liquid epoxy resin composition was capable of giving a cured product with low stress.

Further, the semiconductor device obtained in the embodiment is
It was confirmed that the temperature cycle and flexibility were superior to those of the comparative example.

[0048]

Since the liquid epoxy resin compositions according to claims 1 to 3 of the present invention are configured as described above, the liquid epoxy resin compositions according to claims 1 to 3 of the present invention. According to the above, a liquid epoxy resin composition having low viscosity, good handleability, suitable for forming a resin sealing layer by spot sealing, bleeding-free, and capable of giving a cured product excellent in low stress Is obtained.

Since the semiconductor device according to claims 4 and 5 of the present invention is configured as described above, according to the semiconductor device according to claims 4 and 5 of the present invention, the temperature cycle and the flexibility Excellent in.

Claims (5)

[Claims] 1. A liquid epoxy resin composition comprising an epoxy-modified silicone oil having an epoxy equivalent of 260 or less, a phenol-based curing agent, a curing accelerator and a filler. 2. The liquid epoxy resin composition according to claim 1, wherein the viscosity of the epoxy-modified silicone oil is 300 centipoise or less at 25 ° C. 3. The liquid epoxy resin composition according to claim 1, wherein the phenol-based curing agent is a phenol novolac resin. 4. A semiconductor device, which is encapsulated with the liquid epoxy resin composition according to any one of claims 1 to 3. 5. The semiconductor device according to claim 4, which is encapsulated with the liquid epoxy resin composition to a film thickness of 0.5 mm or less.