JPH10158480A - Epoxy resin composition for semiconductor encapsulation and semiconductor device using the same - Google Patents

Abstract

(57) Abstract: An epoxy resin composition for semiconductor encapsulation which does not require pre-processing when mounted on an electronic device, and which is resistant to heating during solder mounting and has excellent low stress properties, and this epoxy resin. Provided is a semiconductor device which is sealed with a composition and has excellent reliability at the time of solder mounting. A semiconductor element is encapsulated using an epoxy resin composition for encapsulating a semiconductor, comprising the following components (A) and (B) as main components and also containing the following components (C) and (D): I do. (A) Biphenyl type epoxy resin. (B) a phenolic resin. (C) an organic phosphorus compound. (D) metaboric acid.

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 which is excellent in moldability, crack resistance during solder reflow, moldability and workability during molding, and a semiconductor device using the same. Things.

[0002]

2. Description of the Related Art Semiconductor elements such as transistors, ICs, and LSIs have conventionally been sealed with plastic packages or the like to form semiconductor devices from the viewpoint of protection from the external environment and easy handling of the semiconductor elements. A typical example of this type of package is a dual in-line package (DIP). This DI
P is a so-called pin insertion type, in which a semiconductor device is attached by inserting pins into a mounting board.

In recent years, the integration and speed of LSI elements have been increasing, and the density of mounting has been increasing due to the demand for smaller and more sophisticated electronic devices. From such a viewpoint, a surface mount type package is mainly used instead of a pin insertion type package such as DIP. In a semiconductor device using a package of this type, pins are taken out in a plane, and the pins are fixed directly to the surface of a mounting board using solder or the like. Such a surface mount type semiconductor device is configured so that pins can be taken out in a planar manner.
In addition, it has the advantages of being thin, light, and small, and therefore has the advantage that it occupies a small area on the mounting board, and has the advantage that it can be mounted on both sides of the board.

[0004]

However, if the package itself has absorbed moisture before surface mounting in a semiconductor device using the above-mentioned surface mounting type package, the package is mounted on the package by the vapor pressure of moisture during solder mounting. There is a problem that cracks occur. That is, as shown in FIG. 1, in the surface-mounted semiconductor device (package) 3,
As shown by arrow A, moisture from the outside is
, And mainly stays on the front surface of the Si chip 7, the back surface of the die bond pad 4, and the paste portion (adhesive layer) 9 formed between the Si chip 7 and the die bond pad 4. Then, when solder surface mounting such as IR reflow is performed, the accumulated water is vaporized by heating during solder mounting, and the vapor pressure generated as shown in FIG. The space is separated to form the gap 10. further,
As shown in FIG.
When the sealing resin layer 1 on the back surface of the die bond pad 4 is pushed downward, the voids 5 are newly formed on the back surface portion of the die bond pad 4 and cracks 6 are generated in the package 3 at the same time. . The reliability of the semiconductor device having such cracks 6 is significantly reduced due to intrusion of moisture from the outside. Further, expansion of the package 3 when the crack 6 occurs causes problems such as insufficient solder mounting.

[0005] As a solution to such a problem, a method of sealing a semiconductor element with a sealing resin, packing the obtained semiconductor device as a whole in a moisture-proof package, and opening and using it immediately before surface mounting, or a method of surface mounting. Immediately before, the semiconductor device is dried at a high temperature and then soldered.
However, such a pretreatment method has a problem that the manufacturing process is lengthened and the equipment needs to be enhanced.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and does not require any pretreatment when mounting on an electronic device, and has a low stress property capable of withstanding heating during solder mounting. It is an object of the present invention to provide an epoxy resin composition and a semiconductor device sealed with the epoxy resin composition and having excellent reliability at the time of solder mounting.

[0007]

In order to achieve the above object, the present invention comprises the following components (A) and (B) as main components and combines the following components (C) and (D). A first subject is a semiconductor sealing epoxy resin composition to be contained, and a second subject is a semiconductor device in which a semiconductor element is sealed using the above-described semiconductor sealing epoxy resin composition. . (A) Biphenyl type epoxy resin. (B) a phenolic resin. (C) an organic phosphorus compound. (D) metaboric acid.

As methods for preventing the occurrence of package cracks, there are a method for controlling moisture absorption in a sealing resin,
There are three methods that can be considered: a method for increasing the adhesion between the back surface of the die bond pad and the surface of the semiconductor element and the sealing tree, and a method for increasing the toughness of the sealing resin itself. And, the present invention enhances the toughness of the sealing resin based on the above method among the above three methods, and by imparting a high toughness capable of withstanding the stress generated in the package. This is to improve the crack resistance of the package itself during soldering.

That is, based on the above-mentioned concept, the present inventors have made intensive studies on a technique for improving the toughness of the sealing resin. In the process, we focused on the curability of the epoxy resin composition, which is the material for forming the sealing resin, and conducted a series of studies on various compounds that act as curing accelerators among the components that make up this epoxy resin composition. Stacked. As a result, by using an organic phosphorus compound and metaboric acid as a curing accelerator together with a biphenyl type epoxy resin and a phenol resin as a curing agent, the toughness of the intended sealing resin is significantly improved. It has been found that the present invention can be performed, and the present invention has been reached. Furthermore, as a result, it has also been found that in a semiconductor device resin-sealed using the above-mentioned epoxy resin composition for semiconductor encapsulation, generation of cracks during soldering is suppressed and solder crack resistance is improved.

When the mixing ratio of the organic phosphorus compound and the metaboric acid is set in a specific range with respect to the phenol resin, problems such as a delay in curing time and a decrease in fluidity of the sealing material do not occur. It becomes even more preferable.

[0011]

Next, an embodiment of the present invention will be described.

The epoxy resin composition for semiconductor encapsulation of the present invention uses a biphenyl type epoxy resin (component A) and a phenol resin (component B) as main components of a curing system, and further comprises an organic phosphorus compound (component C). And metaboric acid (D component) are used in combination, and usually,
It is in the form of a powder or a tablet obtained by compressing it.

The above biphenyl type epoxy resin (component A)
Has a melting point exceeding room temperature and presenting as a solid or a highly viscous liquid at room temperature, and is specifically represented by the following general formula (1).

[0014]

Embedded image

In the above formula (1), it is preferable that R _{1 to} R ₄ have a hydrogen atom or a methyl group.
Biphenyl type epoxy resins in which _{1 to} R ₄ are all methyl groups are exemplified. And as the epoxy resin component,
Another epoxy resin may be used in combination with the biphenyl type epoxy resin, or a reacted resin may be used. Examples of the other epoxy resin include, but are not particularly limited to, commonly used epoxy resins, for example, various epoxy resins such as cresol novolak type epoxy resin, phenol novolak type epoxy resin, biphenyl type epoxy resin, and bisphenol type epoxy resin. Can be

The phenol resin (component B) used together with the above-mentioned component A acts as a curing agent and is not particularly limited. For example, a novolak-based phenol resin, an aralkyl-based phenol resin and the like are appropriately used. . Among them, it is preferable to use an aralkyl-based phenol resin from the viewpoint of low hygroscopicity.

The above biphenyl type epoxy resin (component A)
It is preferable that the mixing ratio of the phenol resin and the phenol resin (component B) is set such that the hydroxyl group in the phenol resin is 0.8 to 1.2 equivalent per 1 equivalent of the epoxy group in the epoxy resin.

The organic phosphorus compound (component C) used together with the above components A and B serves as a curing accelerator and is not particularly limited.
For example, phosphine compounds such as triphenylphosphine, tributylphosphine, and trioctylphosphine, and phosphonium compounds such as tetraphenylphosphonium and tetraphenylborate are preferably used. Among them, triphenylphosphine is particularly preferably used in terms of heat resistance of the molded product and curability at the time of molding. These may be used alone or in combination of two or more.

The mixing ratio of the organic phosphorus compound (component C) is usually set in the range of 2 to 10 parts with respect to 100 parts by weight (hereinafter abbreviated as "parts") of the phenol resin (component B). You. Particularly preferred is 2 to 5 parts. That is, if the compounding ratio of the organic phosphorus compound (component C) is less than 2 parts, the curing speed is slow and the package molding may take a long time. If it exceeds 10 parts, the fluidity of the sealing resin is reduced. This is because there is a tendency.

The metaboric acid (component D) used together with the components A to C functions as a curing accelerator similarly to the organic phosphorus compound (component C).
This is indicated by HBO ₂ .

The mixing ratio of the above metaboric acid (D component) is as follows:
0.1 parts with respect to 100 parts of the phenol resin (B component)
It is preferable to set the range of 1.0 to 1.0 part. Particularly preferably, it is 0.2 to 0.5 part. That is, if the mixing ratio of the above-mentioned metaboric acid (D component) is less than 0.1 part, it is difficult to sufficiently improve the toughness of the sealing resin, which is the object of the present invention. This is because there is a tendency that the curability of the product is reduced and a long time is required for molding the package.

As described above, in the present invention, from the viewpoint of improving the toughness of the sealing resin, the curing accelerator is used in combination with the organic phosphorus compound as the component C and the metaboric acid as the component D. More preferably, by setting each of the above two components to a specific ratio with respect to the phenol resin as a curing agent, a significant improvement in the toughness of the sealing resin, which could not be achieved conventionally, can be obtained. This is the most important feature of the present invention. Then, the above organic phosphorus compound (component C) and metaboric acid (D
(C / D) is a weight ratio of C / D
It is preferable to set D in the range of 2 / 0.3 to 4 / 0.4.

The epoxy resin composition of the present invention contains the above A
Usually, an inorganic filler is blended together with the components D to D.
Examples of the inorganic filler include crystalline silica powder and fusible silica powder. Further, other than the above silica powder, alumina powder, beryllium oxide powder and the like can be used. These may be used alone or in combination of two or more. It is preferable that the amount of such an inorganic filler is set in the range of 60 to 90% by weight of the entire epoxy resin composition.

Suitable combinations of the above-mentioned components A to D and the inorganic filler in the epoxy resin composition for semiconductor encapsulation of the present invention include low hygroscopicity, heat resistance of the molded product, curability of the molded product and molding. From the viewpoint of improving the toughness of the product, the biphenyl type epoxy resin alone as the component A, the aralkyl type phenol resin as the component B, the triphenylphosphine as the component C, the metaboric acid as the component D, and the inorganic filler And a combination of fusible silica powders.

Further, in addition to the above-mentioned components A to D and the inorganic filler, a flame retardant, a coupling agent, a wax and the like can be appropriately added to the epoxy resin composition of the present invention, if necessary.

As the flame retardant, a novolak type brominated epoxy resin, a brominated bisphenol A type epoxy resin and the like are appropriately used. Further, antimony trioxide or antimony pentoxide can be used as a flame retardant auxiliary.

As the above-mentioned coupling agent, methoxysilane or ethoxysilane such as glycidyl ether type, amine type and thiocyan type may be used alone or in combination of two or more. And, as a method of its use, a method of dry-blending with the above-mentioned inorganic filler, or a method of preliminarily heating and reacting with the inorganic filler, and a method of pre-mixing with the organic component material are appropriately selected. You.

Examples of the wax include compounds such as higher fatty acids, higher fatty acid esters and higher fatty acid calcium, and these can be used alone or in combination of two or more.

The epoxy resin composition for semiconductor encapsulation of the present invention can be produced, for example, as follows. That is, the above-mentioned components A to D and the inorganic filler, and if necessary, the above-mentioned other additives are appropriately mixed and preliminarily mixed, and then melt-kneaded in a kneading machine such as a mixing roll machine in a heating state, and cooled to room temperature. After that, it can be manufactured by passing through a series of steps of crushing by known means and tableting as required.

The encapsulation of a semiconductor element using such an epoxy resin composition for encapsulating a semiconductor is not particularly limited, and can be performed by a known molding method such as ordinary transfer molding.

The semiconductor device obtained in this manner can be obtained by using a combination of an organophosphorus compound contained in an epoxy resin composition for semiconductor encapsulation, which is a material for forming the encapsulation resin layer, and metaboric acid to form an encapsulation resin. Toughness has been improved and
A package crack during solder reflow hardly occurs, and excellent reliability after solder mounting can be obtained.

Next, examples will be described together with comparative examples.

[0033]

EXAMPLES 1 TO 7 AND COMPARATIVE EXAMPLES 1 TO 7 The components shown in Tables 1 and 2 below were blended in the proportions shown in the table, and 90 to 11
The mixture was melted and kneaded for 3 minutes in a roll kneader heated to 0 ° C. Next, after cooling this melt, it was pulverized, and further tableted to obtain an epoxy resin composition for semiconductor encapsulation.

[0034]

[Table 1]

[0035]

[Table 2]

Next, using the epoxy resin compositions in tablet form obtained in the above Examples and Comparative Examples, a test piece for thermal mechanical analysis (TMA), a test piece for flexural strength, a moisture absorption rate The test pieces for measurement were each formed by transfer molding. In addition, a semiconductor element designed for examining and evaluating corrosion of an aluminum electrode is provided in a 16-pin dual in-line package (16 pi).
n-DIP) by transfer molding,
A semiconductor device for evaluating moisture resistance reliability was manufactured. In order to confirm the occurrence of package cracks during solder mounting, 8
0 pink wad flat package (80pin-QF
P: 20 mm x 14 mm x thickness 2.0 mm) and 8 mm x
A semiconductor element having a size of 7 mm × 7 mm was mounted on an 8 mm die bond pad, and a semiconductor device was manufactured by the same transfer molding as described above.

Then, the glass transition temperature and the coefficient of thermal expansion of the cured product of each epoxy resin composition were determined from the TMA test piece, and JIS-K-69 from the bending strength test piece.
Based on No. 11, the flexural strength and flexural modulus of the cured product of each epoxy resin composition and the amount of deflection of the cured resin product were measured at 25 ° C and 220 ° C, respectively.

Further, the test piece for measuring the moisture absorption (diameter 5
(0 mm × 1 mm thick disk-shaped molded product), the moisture absorption of the cured product of each epoxy resin composition was measured. The above-mentioned moisture absorption showed the value after 168 hours at 85 ° C./85% RH.

In order to evaluate the humidity resistance reliability, the semiconductor device (16 pin-DIP) was used at 121 ° C.
/ 100% RH pressure cooker test (hereinafter referred to as “P
CT), and the number of defective elements after 1000 hours was measured (the initial number of elements was 40).

Next, using the above-described semiconductor device (80 pin-QFP) for evaluating package cracks, 85 ° C./8
After absorbing moisture for 168 hours under environmental conditions of 5% RH, 2
The package was immersed in a molten solder bath at 60 ° C. for 10 seconds to measure the number of cracks in the package (the initial number of packages was 10). Further, the adhesive strength between the epoxy resin composition and the lead frame and the semiconductor element was measured by the following method. That is, as shown in FIG. 4, a truncated cone-shaped tablet (upper surface diameter 9 mm × lower surface diameter 11 mm × height 10 mm) 12 made of each epoxy resin composition was prepared.
The two alloy alloy plates 13 were mounted by bonding. Then, as shown in FIG. 5, a force was applied to the tablet 12 on the 42-alloy alloy plate 13 in the direction of arrow F, and the shearing force at that time was measured to determine the adhesive force. Further, the curability (degree of cure) of the resin at 175 ° C. and a molding time of 60 seconds at the time of molding of the 80-pin-QFP was measured for the package portion and the runner portion of the transfer molding machine with a Shore hardness meter. These results are shown in Tables 3 and 4 below.
Are shown together.

[0041]

[Table 3]

[0042]

[Table 4]

From the results shown in Tables 3 and 4, in all the products of Examples, the combined use of triphenylphosphine and metaboric acid shows the strength and the amount of bending in the bending test of any of the resins at 25 ° C. and 220 ° C. Is increased, indicating that the toughness is excellent. As a result, for example, when Examples 1 and 2 are compared with Comparative Examples 1 to 3 in which metaboric acid is not blended, cracking rates during solder mounting are much lower in Examples 1 and 2. Further, in Comparative Example 4 in which metaboric acid was blended without blending triphenylphosphine, molding was not possible because the composition was not cured, and thus various properties of the cured product could not be measured. Further, in Comparative Example 5 using triphenyl borate, which is a borate ester compound, instead of metaboric acid, the amount of deflection of the molded product at a high temperature was not sufficient, and the toughness was not improved. Also,
Adhesion is reduced. And, instead of metaboric acid,
In Comparative Example 6 using orthoboric acid, the gelation time of the sealing material was prolonged, and as a result, the curability was reduced. In addition, the adhesiveness was also reduced. Furthermore, in Comparative Example 7 using a cresol novolak type epoxy resin instead of a biphenyl type epoxy resin, the resin has a high modulus of elasticity at high temperatures and a small amount of bending, so that the toughness of the resin during soldering decreases. ing. Further, peeling in the package is likely to occur due to a decrease in adhesive strength and an increase in the moisture absorption rate, and a reflow crack is likely to occur.

[0044]

As described above, the present invention contains an organic phosphorus compound (component C) and metaboric acid (component D) together with a biphenyl type epoxy resin (component A) and a phenol resin (component B). A semiconductor element is resin-encapsulated using an epoxy resin composition for semiconductor encapsulation.
For this reason, the toughness of the sealing resin is remarkably improved, and it becomes superior to the stress generated inside the package. For example, even under severe conditions at the time of solder mounting, the package does not crack and has excellent heat resistance. A semiconductor device having impact reliability and moisture resistance can be obtained.

Then, the above-mentioned organic phosphorus compound (component C)
By setting the mixing ratios of metaboric acid (D component) and the phenolic resin (B component) in a specific range, problems such as a delay in curing time and a decrease in fluidity of the sealing material do not occur. Is more preferable.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a process of crack generation in a conventional surface mount type semiconductor device.

FIG. 2 is a cross-sectional view showing a process of crack generation in a conventional surface mount type semiconductor device.

FIG. 3 is a cross-sectional view showing a process of generating a crack in a conventional surface mount semiconductor device.

FIG. 4 is a perspective view showing a method for measuring an adhesive force between a lead frame material and each epoxy resin composition.

FIG. 5 is a perspective view showing a method for measuring an adhesive force between a lead frame material and each epoxy resin composition.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H01L 23/31 (72) Inventor Masahiro Hata 1-2-1, Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation

Claims (3)

[Claims] 1. An epoxy resin composition for encapsulating a semiconductor, comprising the following components (A) and (B) as main components and the following components (C) and (D): (A) Biphenyl type epoxy resin. (B) a phenolic resin. (C) an organic phosphorus compound. (D) metaboric acid. 2. The compounding ratio of the organic phosphorus compound (component (C)) is 100% with the phenol resin (component (B)).
The amount is set in the range of 2 to 10 parts by weight based on 100 parts by weight of the phenolic resin [component (B)].
The epoxy resin composition for semiconductor encapsulation according to claim 1, which is set in a range of 1 to 1.0 part by weight. 3. A semiconductor device comprising a semiconductor element encapsulated by using the epoxy resin composition for semiconductor encapsulation according to claim 1.