JPH05226523A - Semiconductor device - Google Patents

Abstract

PURPOSE:To eliminate the need of a pretreatment at the time of mounting of a semiconductor device to an electronic equipment and moreover, to contrive the improvement of a reduction in a stress capable of withstanding a heating at the time of solder packaging by a method wherein an epoxy resin composition containing a specified phenolic resin is used. CONSTITUTION:A semiconductor chip is sealed with an epoxy resin composition containing (A) and (B) below as its main components. (A) is an epoxy resin. (B) is a phenolic resin which is shown by the diagram. Thereby, the adhesive strength of the element to a sealing resin is superior and a reduction in the moisture adsorption of the sealing resin itself and a reduction in the elastic modulus of the resin itself can be realized without lowering a glass transition temperature. Accordingly, a crack is never generated in a package even under such a severe condition as that at the time of solder packaging and a semiconductor device can be provided with a superior reliability of heat resistance and humidity resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin-encapsulated semiconductor device resin-encapsulated with an epoxy resin composition, which has excellent package crack resistance during soldering and thermal stress caused by the resin composition. The present invention relates to a semiconductor device having low reliability and excellent reliability.

[0002]

2. Description of the Related Art Semiconductor elements such as transistors, ICs and LSIs are usually encapsulated with an epoxy resin composition to be a semiconductor device. A typical example of this type of package is the dual in-line package (DI
There is P). This DIP is a pin insertion type,
A semiconductor device is attached by inserting pins into a mounting board.

In recent years, semiconductor devices such as LSI chips have been highly integrated and operated at high speed. In addition, the demand for high-performance electronic devices with a small size has led to an increase in packaging density.
From this point of view, a surface mount type package is becoming mainstream instead of a pin insertion type package such as DIP. In a semiconductor device using this type of package, pins are taken out in a plane and are fixed directly to the surface of a mounting board by soldering or the like. Such a surface-mounting type semiconductor device has a merit that the pins can be taken out in a plane, and is thin, light, and small, and thus has a merit that it occupies a small area on the mounting board. In addition, it has an advantage that it can be mounted on both sides of the board.

[0004]

However, in the semiconductor device using the surface mount type package as described above, when the package itself absorbs moisture before surface mounting, the package is liable to have a moisture vapor pressure during solder mounting. There is a problem that cracks occur in the. That is, in the surface-mounting type semiconductor device as shown in FIG. 1, moisture penetrates into the package 3 through the sealing resin 1 as shown by an arrow A, and mainly, the front surface of the Si-chip 7 or the back surface of the die bond pad 4. Stay in. Then, when solder surface mounting such as vapor phase soldering is performed, the accumulated water is vaporized by heating in the solder mounting, and by the vapor pressure thereof,
As shown in FIG. 2, the resin portion on the back surface of the die bond pad 4 is pushed downward to form a void 5 therein, and at the same time, a crack 6 is generated in the package 3. 1 and 2
In, 8 is a bonding wire.

As a solution to such a problem, after the semiconductor element is sealed with a package, the obtained semiconductor device is packaged in a moisture-proof manner and opened immediately before surface mounting, or before the surface mounting. The semiconductor device is 100 ° C.
A method has been proposed and has been already implemented in which it is dried for 24 hours and then solder mounting is performed. However, according to such a pretreatment method, there are problems that the manufacturing process is lengthened and that it is troublesome.

On the other hand, with the increase in size of semiconductor elements, there are problems caused by thermal stress such as generation of passivation cracks and aluminum slides. In order to solve such a problem, a soft substance such as rubber or silicone is usually dispersed in a resin composition, and the resin composition is used to seal the resin to reduce the stress. However, if the above method is adopted, the water vapor diffusion coefficient of the resin composition increases, which is disadvantageous from the viewpoint of occurrence of passivation cracks at the time of solder mounting described above.

The present invention has been made in view of the above circumstances, and provides a semiconductor device which does not require pretreatment for mounting on an electronic device and which is excellent in low stress capable of withstanding heating during solder mounting. Is its purpose.

[0008]

In order to achieve the above object, the semiconductor device of the present invention encapsulates a semiconductor element using an epoxy resin composition containing the following (A) and (B) as a main component. Take the configuration. (A) Epoxy resin. (B) A phenolic resin represented by the following general formula (1).

[Chemical 5] [In said Formula (1), m is an integer of 0-5. ]

[0009]

The method of preventing package cracks during soldering is to suppress moisture absorption in the encapsulating resin, increase the adhesive force between the back surface of the die bond pad and the surface of the semiconductor element and the encapsulating resin, and seal at high temperature. There are four possible methods of increasing the strength of the stop resin and decreasing the elastic modulus of the sealing resin at high temperatures. The present invention achieves the above-mentioned and the other methods by using the special phenol resin represented by the above general formula (1), and makes it possible to improve the package crack resistance during soldering and the low stress at the same time. The inventors have found that it is possible to reach the present invention.

The term "epoxy resin composition containing a main component" is intended to include a case where the epoxy resin composition consists of only a main component.

Next, the present invention will be described in detail.

The epoxy resin composition used in the present invention is obtained by using an epoxy resin (component A) and a special phenol resin (component B), and usually has a powder or tablet form. There is.

The epoxy resin (component A) is not particularly limited, and examples thereof include those usually used. Examples thereof include various epoxy resins such as cresol novolac type, phenol novolac type, novolac bis A type and bisphenol A type. The above-mentioned novolac type epoxy resin usually has an epoxy equivalent of 150 to 2
A cresol novolac type epoxy resin having an epoxy equivalent of 180 to 210 and a softening point of 60 to 110 ° C. is generally used. Then, in addition to the above-mentioned normally used epoxy resin, a package having further excellent moisture resistance reliability can be obtained by using a special epoxy resin represented by the following general formula (2).

[0014]

[Chemical 6] [In the above formula (2), n is 0 to 3. ]

As the special epoxy resin (component A) represented by the above general formula (2), epoxy equivalent of 245 to 28 is used.
5, those having a softening point of 60 to 100 ° C. are preferably used. As described above, the epoxy resin component (A component) may be formed only by using the above-mentioned normally used epoxy resin, or the epoxy resin component (A component) may be formed by only the above-mentioned special epoxy resin. Moreover, you may make it use together with the epoxy resin normally used above. In the above case, all of the epoxy resin components are composed only of commonly used epoxy resins, and in the above case, all of the epoxy resin components are composed of only the special epoxy resin represented by the general formula (2). Composed. Further, in the above case, a part of the epoxy resin component is composed of the special epoxy resin represented by the general formula (2).
Then, it is preferable to use a special epoxy resin as in the case of or above rather than the case of using only the above-mentioned normally used epoxy resin. In particular, it is preferable to set the above-mentioned special epoxy resin to 50% by weight (hereinafter abbreviated as "%") of the entire epoxy resin component.

The above-mentioned special phenol resin (component B) is
It acts as a curing agent for the epoxy resin (component A) and is represented by the following general formula (1).

[0017]

[Chemical 7] [In said Formula (1), m is an integer of 0-5. ]

As such a special phenol resin (component B), the hydroxyl group equivalent is 165 to 180 and the softening point is 80.
It is preferable to use one having a temperature of up to 130 ° C. The above-mentioned special phenol resin may constitute the curing agent component by itself, or may be used in combination with any other commonly used phenol resin. In the former case, all of the curing agent components are composed of the special phenol resin represented by the general formula (1), and in the latter case, a part of the curing agent components are represented by the general formula (1). It will be composed of a special phenol resin. Examples of the above-mentioned usually used phenol resin include phenol novolac and cresol novolac. These novolac resins have a softening point of 50 to 110 ° C. and a hydroxyl equivalent of 70 to 150.
It is preferable to use the above. When the special phenol resin represented by the general formula (1) and such a commonly used phenol resin are used in combination, the special phenol resin is set to 50% or more of the entire curing agent component. Is preferable, and particularly preferably 70% or more.

The mixing ratio of the special epoxy resin (component A) and the special phenol resin (component B) is 0.8 to 1.2 hydroxyl groups in the phenol resin per equivalent of epoxy group in the epoxy resin. It is preferable to mix them so that the amounts are equivalent.

The epoxy resin composition used in the present invention may include an inorganic filler, a curing accelerator, and
Flame retardants, coupling agents, waxes, release agents, etc. are used.

Examples of the inorganic filler include not only crystalline and fusible silica, but also aluminum oxide, beryllium oxide, silicon carbide, silicon nitride and the like. The content of this inorganic filler is preferably set in the range of 60 to 95% in the epoxy resin composition. It is particularly preferably set to 75 to 90% or more. That is, when the content of the inorganic filler is less than 60%, the moisture absorption amount of the sealing resin increases and the strength decreases, so that the package crack resistance during soldering deteriorates. Conversely, 95%
This is because the melt viscosity of the encapsulating resin increases if the value exceeds the above range, and a molding defect such as an unfilled portion or wire flow occurs during molding, which tends to occur.

Examples of the curing accelerator include amine-based, phosphorus-based, boron-based and phosphorus-boron-based curing accelerators, which may be used alone or in combination.

As the flame retardant, compounds such as novolac type brominated epoxy resin or bis A type brominated epoxy resin, antimony trioxide and antimony pentoxide may be appropriately used alone or in combination.

As the coupling agent, methoxy or ethoxysilane such as glycidyl ether type, amine type, thiocyan type, urea type, etc. is appropriately used alone or in combination. The coupling agent is used by dry blending with the filler, by preheating reaction, or by premixing with the organic component raw material, but is not particularly limited.

Examples of the above wax include compounds such as higher fatty acids, higher fatty acid esters, and higher fatty acid calcium, which may be used alone or in combination.

The epoxy resin composition used in the present invention is blended with a rubber component such as silicone oil, silicone rubber, and synthetic rubber in addition to the above additives to reduce stress, and in a moisture resistance reliability test. An ion trap agent such as hydrotalcite may be added for the purpose of improving reliability.

The epoxy resin composition used in the present invention can be manufactured, for example, as follows. That is, first, an epoxy resin (component A), a special phenol resin (component B) and the above-mentioned other additives are appropriately mixed and premixed. Then, a kneading machine such as a mixing roll machine is used to knead in a heated state to melt-mix, and this is cooled to room temperature. Then, it can be manufactured by a series of steps of crushing by known means and tableting if necessary.

The encapsulation of the semiconductor element using such an epoxy resin composition is not particularly limited and can be carried out by a known molding method such as ordinary transfer molding.

The semiconductor device thus obtained realizes a low moisture absorption and a low elastic modulus of the sealing resin itself without lowering the glass transition temperature by the action of the special phenol resin (component B). In addition, the adhesive strength between the semiconductor element and the sealing resin is improved, and the heat resistance and humidity resistance are excellent.

[0030]

As described above, the semiconductor device of the present invention is formed by sealing the semiconductor element with the epoxy resin composition containing the special phenol resin (component B). Therefore, the adhesive strength between the semiconductor element and the sealing resin is excellent, and the moisture absorption and the elastic modulus of the sealing resin itself can be realized without lowering the glass transition temperature. Therefore, even under severe conditions such as solder mounting, excellent heat resistance and humidity resistance are achieved without causing package cracks.

Next, examples will be described together with comparative examples.

[0032]

Examples 1 to 9 and Comparative Examples 1 to 2 The components shown in Tables 1 to 3 below were blended in the proportions shown in the same table, and kneaded in a mixing roll machine at 100 ° C. for 10 minutes to obtain a sheet-like epoxy. A resin composition was obtained. Then, the obtained sheet-shaped epoxy resin composition was pulverized to obtain a target powdery epoxy resin composition.

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

[Table 3]

Next, Examples 1-9 and Comparative Examples 1-2
A semiconductor device was obtained by molding a semiconductor element by transfer molding using the powdery epoxy resin composition obtained in the above. This semiconductor device is an 80-pin four-way flat package (QFP) (20 mm x 14 mm x thickness 2.
5mm), 7mm x 7mm die bond plate, 6.5mm
It has a chip size of × 6.5 mm. Regarding the semiconductor device thus obtained, 260 ° C. × 10
The solder was dipped for 2 seconds to measure the critical moisture absorption time under the condition of 85 ° C./85% RH until the package crack occurred. In addition, using the epoxy resin compositions obtained in Examples 1 to 9 and Comparative Examples 1 and 2, a thickness of 1 mm and a diameter of 50
mm-shaped disc-shaped cured product was prepared (curing condition: 180 ° C. × 5 hours), and the disc-shaped cured product was 85 ° C. × 85% R
It was made to absorb moisture under H condition for 500 hours, and the saturated moisture absorption rate was measured. Furthermore, the flexural strength and elastic modulus of the cured product are determined by JIS-
It was measured at room temperature and under 260 ° C according to K-6911 5.17. Then, Examples 1-9 and Comparative Examples 1-2
The adhesive force between the cured product of the epoxy resin composition obtained in 1. and the semiconductor element was measured. These results are shown in Tables 4 to 6 below.
It was shown to. In addition, the said adhesive force was measured as follows. That is, as shown in FIGS. 3 and 4, the upper surface has a diameter a = 11 mm, the lower surface has a diameter b = 9 mm, and the height h =
A 10 mm frustoconical cured product 10 was prepared, and the shear adhesive force between the truncated conical cured product 10 and the semiconductor element 11 was measured.

Further, the packages obtained in the same manner as above using the epoxy resin compositions obtained in Examples 1 to 9 and Comparative Examples 1 to 2 were used under the conditions of 85 ° C./85% RH.
After absorbing moisture for 2 hours, the solder was immersed at 260 ° C. for 10 seconds. This was left under 121 ° C. × 100% RH, and the moisture resistance deterioration time in which 50% of defects due to corrosion of the aluminum pattern portion of the semiconductor element surface occurred was measured and evaluated. Furthermore, the package obtained in the same manner is used at 150 ° C. for 5 minutes.
A thermal cycle test (TCT test) of 300 cycles at -60 ° C / 5 minutes was performed to measure the amount of deformation of the aluminum pattern wiring portion on the surface of the semiconductor element due to thermal stress received from the sealing resin. The results are also shown in Tables 4 to 6 below.

Further, Examples 1 to 9 and Comparative Example 1 described above
Using the epoxy resin compositions obtained in Examples 1 to 2, the flow characteristics of spiral flow and minimum melt viscosity at 175 ° C. of the epoxy resin compositions were measured, and the results are also shown in Tables 4 to 6 below. In addition, the said spiral flow was measured based on EMM1-1-66. The minimum melt viscosity was measured using a Koka type flow tester (manufactured by Shimadzu Corporation).

[0039]

[Table 4]

[0040]

[Table 5]

[0041]

[Table 6]

From the results of Tables 4 to 6 above, the products of Examples are
Excellent adhesion, low saturated water absorption rate, and excellent cured product properties. In addition, the cracking limit moisture absorption time and the 50% defect occurrence time are longer than those of the comparative example, and the amount of wiring deformation is small. From this, it is understood that the products of Examples have excellent moisture resistance and heat resistance reliability.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view illustrating a situation in which a package crack occurs in a conventional semiconductor device.

FIG. 2 is a vertical cross-sectional view illustrating a situation where a package crack occurs in a conventional semiconductor device.

FIG. 3 is a front view of a cured product of an epoxy resin composition.

FIG. 4 is a side view of a cured product of an epoxy resin composition.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Minoru Nakao, 1-2, Shimohozumi, Ibaraki, Osaka Prefecture Nitto Denko Corporation (72) Takashi Takashi, 1-2, Shihohozumi, Ibaraki, Osaka Prefecture Nitto Denko Corporation (72) Inventor Hisashi Nakajima 1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Denko Corporation

Claims (4)

[Claims] 1. A semiconductor device obtained by encapsulating a semiconductor element using an epoxy resin composition containing the following (A) and (B) as a main component. (A) Epoxy resin. (B) A phenolic resin represented by the following general formula (1). [Chemical 1] [In said Formula (1), m is an integer of 0-5. ] 2. The epoxy resin as the component (A),
The semiconductor device according to claim 1, which is an epoxy resin represented by the following general formula (2). [Chemical 2] [In said Formula (2), n is an integer of 0-3. ] 3. An epoxy resin composition for semiconductor encapsulation containing the following (A) and (B) as main components. (A) Epoxy resin. (B) A phenolic resin represented by the following general formula (1). [Chemical 3] [In said Formula (1), m is an integer of 0-5. ] 4. The epoxy resin as the component (A),
The epoxy resin composition for semiconductor encapsulation according to claim 3, which is an epoxy resin represented by the following general formula (2). [Chemical 4] [In said Formula (2), n is an integer of 0-3. ]