JPH07312401A - Semiconductor device - Google Patents

Abstract

PURPOSE:To provide a semiconductor device which does not need pretreatment at the time of mounting on an electronic apparatus, and is excellent in stress resistance and capable of enduring heating in solder mounting and in humidity resistance reliability after solder mounting. CONSTITUTION:The title semiconductor device is constituted by encapsulating a semiconductor chip in an epoxy resin based composition cured body having the following characteristics (a)-(d). (a): The bending strength of the cured member is larger than or equal to 0.6kg/mm<2> at 260 deg.C. (b): The bending elastic modulus of the cured member is lower than or equal to 65kg/mm<2> at 260 deg.C. (c): The saturation water-absorbing capacity of the cured member is lower than or equal to 0.4wt.% in a 85 deg.C/85% RH atmosphere. (d): The diffusion coefficient (Df30) of the cured member at 30 deg.C is lower than or equal to 6.0X10<-7> mm<2>/sec, the diffusion coefficient (Df85) at 85 deg.C is lower than or equal to 5.0X10<-6>mm<2>/sec, and the relation of Df85/Df30<10.0 is satisfied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device having excellent moisture resistance reliability.

[0002]

2. Description of the Related Art Semiconductor elements such as transistors, ICs, and LSIs are sealed as a semiconductor device by a plastic package or the like from the viewpoint of protecting the external environment and enabling the handling of the element. A typical example of this type of package is a dual in-line package (DIP). This DIP is a pin insertion type, and a semiconductor device is attached by inserting pins into a mounting substrate.

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, surface mounting packages have become mainstream instead of pin insertion type packages such as DIP. In a semiconductor device using this type of package, pins are two-dimensionally taken out and fixed to the surface of the mounting substrate directly by soldering or the like. Such a surface-mount type semiconductor device has features that it is thin, light, and small because the pins can be taken out in a plane, and therefore has an advantage that it occupies a small area on the mounting substrate. 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 mounting package as described above,
If the package itself absorbs moisture before surface mounting,
There is a problem that cracks are generated in the package due to vapor pressure of water during solder mounting. That is, in the surface mount type semiconductor device as shown in FIG. 1, moisture generally penetrates into the package 3 through the sealing resin 1 as indicated by arrow A, and mainly enters the surface of the Si-chip 7 and the die bond pad 4. Stays on the back side of. Then, when solder surface mounting is performed by vapor phase soldering or the like, the accumulated water is vaporized by heating during the solder mounting, and the pressure causes the resin on the back surface of the die bond pad 4 to be evaporated, as shown in FIG. The portion 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, 8 is a bonding wire.

As a solution to such a problem, after sealing a semiconductor element with a package, the entire semiconductor device obtained is moisture-proof packaged 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, in addition to lengthening the manufacturing process,
There is a problem that it takes time.

On the other hand, in order to realize low moisture absorption of the sealing resin, as an epoxy resin composition for semiconductor sealing, for example,
It has been proposed to use an epoxy resin composition containing an epoxy resin having a skeleton represented by the following general formula (4) and a novolac resin represented by the following general formula (5).

[0007]

[Chemical 1]

[0008]

[Chemical 2]

However, when a semiconductor element is encapsulated with the epoxy resin composition, the moisture absorption rate of the encapsulation resin is reduced, but the moisture resistance reliability after solder mounting deteriorates.

The present invention has been made in view of the above circumstances, and does not require pre-processing for mounting on an electronic device.
It is an object of the present invention to provide a semiconductor device that is excellent in low stress resistance that can withstand heating during solder mounting and has high moisture resistance reliability after solder mounting.

[0011]

[Means for Solving the Problems]
Therefore, the semiconductor device of the present invention has the following characteristics (a) to
Semiconducting by a cured epoxy resin composition having (d)
The body element is sealed. (A) The bending strength of the cured product is 0.6 kg / m at 260 ° C.
m²that's all. (B) The flexural modulus of the cured product is 65 kg / m at 260 ° C.
m²Less than. (C) Saturated water absorption of the cured product is 85 ° C./85% RH atmosphere
0.4% by weight or less in the air. (D) Diffusion coefficient (Df of cured product at 30 ° C.)₃₀)But,
Df₃₀= 6.0 × 10 ^-7mm²/ Sec or less, 85 ° C
Diffusion coefficient (Df₈₅) Is Df₈₅= 5.0 x 10
^-6mm²/ Sec or less and the diffusion coefficient Df₃₀
And Df₈₅An epoxy whose ratio of satisfies the following inequality
Cured product of resin composition. Df₈₅/ Df₃₀<10.0

[0012]

According to the present invention, package crack resistance and moisture resistance reliability of the encapsulating resin at a high temperature (215 to 260 ° C.) such as solder mounting can be significantly improved.

In order to obtain the semiconductor device of the present invention, for example, the semiconductor element may be sealed with an epoxy resin composition containing the following components (A) and (B).

(A) An epoxy resin represented by the following general formula (1).

[0015]

[Chemical 3]

(B) A reaction product obtained by prereacting a silane compound represented by the following general formula (2) and a phenol aralkyl resin represented by the following general formula (3).

[0017]

[Chemical 4]

[0018]

[Chemical 5]

The epoxy resin composition used in the present invention is obtained by using the above-mentioned epoxy resin and a curing agent, and is usually in the form of powder or tablets obtained by tableting. ing.

The above-mentioned epoxy resin is not particularly limited and examples thereof include those usually used. Above all,
For example, a biphenyl type epoxy resin represented by the following general formula (1) is preferably used.

[0021]

[Chemical 6]

Thus, the epoxy resin obtained by substituting the lower alkyl group for the aromatic ring having the glycidyl ether group becomes water repellent. The epoxy resin component may be composed of only the special epoxy resin represented by the general formula (1), or may be used in combination with other commonly used epoxy resins. In the former case, the whole epoxy resin is composed of the special epoxy resin of the general formula (1), and in the latter case, a part of the epoxy resin is composed of the special epoxy resin of the general formula (1). The Rukoto. Examples of the epoxy resin usually used 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 is usually an epoxy equivalent of 1
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. When both are used in combination as described above, the epoxy resin represented by the general formula (1) is preferably set to 20% by weight (hereinafter abbreviated as “%”) or more based on the entire epoxy resin component, and particularly preferably Is 50% or more.

The above-mentioned curing agent is represented by the following general formula (2)
A specific silane compound represented by the following general formula (3)
A special reaction product obtained by pre-reacting with a specific phenol aralkyl resin represented by

[0024]

[Chemical 7]

[0025]

[Chemical 8] That is, the special reaction product has the general formula (2)
The organic group X and the alkoxy group Y of the specific silane compound represented by are reacted with the OH group in the specific phenol aralkyl resin represented by the general formula (3) to obtain an alcohol.

As the specific silane compound represented by the above general formula (2), a commonly used silane coupling agent is used, and specifically, N- (2-aminoethyl)-
3-aminopropylmethyldimethoxysilane, N- (2
-Aminoethyl) -3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N, N-bis [(methyldimethoxysilyl) propyl] amine, N, N-bis [ 3- (methyldimethoxysilyl) propyl] ethylenediamine, N, N-bis [3- (trimethoxysilyl) propyl] amine, N, N-bis [3- (trimethoxysilyl) propyl] ethylenediamine, 3- (N,
N-diglycidyl) aminopropyltrimethoxysilane, N-glycidyl-N, N-bis [3- (methyldimethoxysilyl) propyl] amine, N-glycidyl-
N, N-bis [3- (trimethoxysilyl) propyl]
Amine, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane,
3-mercaptotrimethoxysilane, 3-mercaptopropyltrimethoxysilane, N-[(3-trimethoxysilyl) propyl] diethylenetriamine, N-[(3
-Trimethoxysilyl) propyl] triethylenetetramine, N-3-trimethoxysilylpropyl-m-phenylenediamine and the like.

The specific phenol aralkyl resin represented by the above general formula (3) can be obtained by reacting aralkyl ether and phenol with a Friedel-Crafts catalyst. Generally, as the phenol aralkyl resin, a condensation polymerization compound of α, α'-dimethoxy-p-xylene and a phenol monomer is known. The phenol aralkyl resin has a softening point of 70 to 1
It is preferable to use one having a hydroxyl group equivalent of 150 to 220 at 10 ° C. The phenol aralkyl resin may be used in combination with a commonly used phenol resin. Examples of the above-mentioned usually used phenol resin include phenol novolac and cresol novolac. As these novolac resins, those having a softening point of 50 to 110 ° C. and a hydroxyl equivalent of 70 to 150 are preferably used. When the phenol aralkyl resin and the ordinary phenol resin are used in combination, it is preferable to set the phenol aralkyl resin in a proportion of 50% or more of the total amount of the phenol aralkyl resin and the ordinary phenol resin, Particularly preferably 70
% Or more. The pre-reaction product is preferably compounded in such a proportion that the hydroxyl groups in the pre-reaction product are 0.7 to 1.3 equivalents per equivalent of epoxy groups in the epoxy resin. More preferred is 0.8-1.
It is 2 equivalents.

The special reaction product composed of the specific silane compound and the specific phenol aralkyl resin is obtained, for example, as follows. That is, the above-mentioned specific silane compound and specific phenol aralkyl resin are appropriately blended in a reaction vessel equipped with a stirrer, and the mixture is heated at 120 to 180 ° C.
Particularly preferably, the temperature is raised to 130 to 150 ° C. and both are reacted to produce a reaction product. Next, the alcohol produced by this reaction is removed from the system by degassing or the like under the condition of 130 to 180 ° C.

The epoxy resin composition used in the present invention usually contains an inorganic filler and a curing accelerator in addition to the above-mentioned epoxy resin and curing agent, and further contains a flame retardant, a wax and the like as required. Used.

Examples of the above-mentioned inorganic filler include crystalline and fusible silica. Then, it is preferable that the blending amount of the inorganic filler is set to 65% or more of the entire epoxy resin composition. 70% or more is particularly preferable. That is, when the compounding amount of the inorganic filler is less than 65%, the flexural strength of the obtained cured epoxy resin composition at 260 ° C. after saturated moisture absorption is reduced (0.60 kg /
It is from mm to become less than ^2).

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 novolak type brominated epoxy or bis A type epoxy, antimony trioxide and antimony pentoxide are used alone or in combination as appropriate.

As the above-mentioned coupling agent, methoxy or ethoxysilane such as glycidyl ether type, amine type, thiocyan type and urea type is appropriately used alone or in combination. As a method of using the filler, it is possible to dry blend the filler, or carry out a preliminary heating reaction, and further preliminarily mix the organic component raw material.

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.

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

The epoxy resin composition used in the present invention can be manufactured as follows, for example, when the above-mentioned special epoxy resin and reaction product are used. That is, first, a reaction product is prepared by preliminarily reacting the specific silane compound and the specific phenol aralkyl resin under the above conditions. Next, after properly mixing and premixing the reaction product and the epoxy resin, the mixture is kneaded in a heated state by a kneader such as a mixing roll machine to melt-mix, and after cooling to room temperature, by known means. It can be manufactured by a series of steps of crushing 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. Then, in the present invention, a semiconductor device sealed by a cured product satisfying the above-mentioned physical properties (a) to (d) is obtained by molding a semiconductor element using the epoxy resin composition. You can

In the present invention, if the flexural strength of the cured product (a) is less than 0.6 kg / mm ² , the package will crack. Also, the bending elastic modulus of (b) is 65 k.
g / mm ² is exceeded, the saturated water absorption of (c) exceeds 0.4%, and the Df _{30 of} (d) is 6.0 × 10 ⁻⁷ mm ² / sec.
, Df ₈₅ exceeds 5.0 × 10 ⁻⁶ mm ² / sec, and the ratio of the diffusion coefficients Df ₃₀ and Df ₈₅ (Df
_This is because if a material having a characteristic of ₈₅ / Df ₃₀ ) of 10.0 or more is used, the crack resistance also deteriorates.

Usually, as the above epoxy resin composition,
(A) The bending strength of the cured product at 260 ° C. is 0.6 to 1.
Within the range of 5 kg / mm ² , (b) the flexural modulus of the cured product at 260 ° C. is within the range of 30 to 65 kg / mm ² ,
(C) The saturated water absorption of the cured product is below the above value (the lower the better), and (d) the diffusion coefficient (Df ₃₀ ) of the cured product at 30 ° C and the diffusion coefficient (Df) of 85 ° C.
Those whose ₈₅ ) satisfies the above values are used. The adhesive force between the cured product and the semiconductor element is usually 2 kg / m.
m ² or more, preferably 3 kg / mm ² or more, and generally about ² to 8 kg / mm ² .

The above bending strength and bending elastic modulus are
A cured product of an epoxy resin-based composition is prepared, and the temperature is set at 260 ° C., J
It is a value obtained by conducting a test according to IS-K-6911.

The saturated water absorption is 50 mm in diameter by using the obtained epoxy resin composition by transfer press.
mm / thickness 3mm disc, then 85 ℃ /
It is a value obtained by absorbing moisture in an atmosphere of 85% RH for 500 hours. The conditions for the above-mentioned curing and molding are 175 ° C., 2 minutes, 70 kg / mm ² , and after-curing: 175 ° C., 5 hours for an ordinary epoxy resin.

Further, the above diffusion coefficients Df ₃₀ and Df
_{The value of 85} is a value calculated by substituting the water absorption amount of the cured product into the following formula corresponding to short-time moisture absorption in flat plate moisture absorption in Fick type diffusion.

[0043]

[Equation 1]

Since the semiconductor device thus obtained is resin-sealed with the cured epoxy resin composition having the above-mentioned characteristics, it is excellent in moisture resistance reliability, and package cracks and the like do not occur during solder mounting. It never happens.

[0045]

As described above, in the semiconductor device of the present invention, the cured product of itself has a predetermined bending strength, bending elastic modulus,
It is obtained by resin-sealing a semiconductor element with a special epoxy resin composition having a saturated water absorption coefficient and a diffusion coefficient.
Therefore, this product has excellent moisture resistance reliability without causing package cracks even under severe conditions such as solder mounting. In particular, it is highly reliable and optimum for surface mounting of thin flat packages. The special epoxy resin composition is represented by the special epoxy resin represented by the general formula (1), the silane compound represented by the general formula (2), and the general formula (3). It is particularly effective to use an epoxy resin composition obtained by using a pre-reaction product with a phenol aralkyl resin.

Next, examples will be described together with comparative examples.

First, the compounds shown in Table 1 below were prepared prior to the examples.

[0048]

[Table 1]

Next, the phenolic resins C and D shown in Table 1 above are used.
By mixing the silane compounds E, F, and G in the proportions shown in Table 2 below, charging them in a reaction vessel equipped with a stirrer, pre-reacting under the reaction conditions shown in the same table, and degassing (170 ° C.) Reaction products J to N were prepared.

[0050]

[Table 2]

[0051]

Examples 1 to 7 and Comparative Examples 1 to 3 The above reaction products J to
N, epoxy resins A and B, and other additives were blended in the proportions shown in Tables 3 to 5 below and kneaded in a mixing roll machine at 100 ° C. for 10 minutes to obtain a sheet-shaped composition. Then, the obtained sheet-shaped composition is crushed,
A target powdered epoxy resin composition was obtained.

[0052]

[Table 3]

[0053]

[Table 4]

[0054]

[Table 5]

Next, Examples 1 to 7 and Comparative Examples 1 to 3
A semiconductor device was obtained by molding a semiconductor element by transfer molding using the powdery epoxy resin composition obtained in (1). This semiconductor device is an 80-pin four-way flat package (QFP) (20 mm × 14 mm × thickness 2.5 mm), has a die bond plate of 7 mm × 7 mm, and a chip size of 6.5 mm × 6.5 mm. The semiconductor device thus obtained was immersed in solder at 260 ° C., and the limit moisture absorption time at 85 ° C./85% RH until package cracking was measured. Further, using the epoxy resin composition,
A disk-shaped cured product having a thickness of 3 mm and a diameter of 50 mm was produced (molding condition: 175 ° C., 2 minutes, 70 kg / mm ² , after cure: 175 ° C., 5 hours), and the disk-shaped cured product was 85 ° C. The saturated water absorption was measured by allowing it to absorb moisture under x85% RH for 500 hours.

Further, the flexural strength and flexural modulus of the cured product are 260 ° C. according to JIS-K-6911,5.17.
Measured below. Then, the adhesive force between the semiconductor element and the cured product was measured. On the other hand, the diffusion coefficient Df ₃₀ at 30 ° C. and the diffusion coefficient Df ₈₅ at 85 ° C. of the epoxy resin composition were measured by the above formulas, respectively. The results are shown in Tables 6 and 7 below.

The adhesive strength was measured as follows. That is, using the above epoxy resin composition, as shown in FIGS. 3A and 3B, the upper surface has a diameter a = 1.
1mm and the lower surface has a diameter b = 9mm and a height h = 10m
A truncated cone-shaped cured product 10 of m was prepared, and a semiconductor element 11 of 2 mm × 2 mm × thickness 0.4 mm was mounted at the center of the upper surface of the truncated cone-shaped cured product 10. Then, the shear adhesive force between the truncated cone-shaped cured product 10 and the semiconductor element 11 was measured.

[0058]

[Table 6]

[0059]

[Table 7]

From the results shown in Tables 6 and 7, the flexural modulus of the cured epoxy resin composition exceeds 65 kg / mm ² and the Df ₈₅ / Df ₃₀ exceeds 10. Below 0.6 kg / mm ² , the flexural modulus is 6
In all of the products of Comparative Example 4 in which the amount exceeds 5 kg / mm ² , the cracking limit moisture absorption time is short. In addition, the product of Comparative Example 2 is
Since a normal phenol resin is used, the moisture resistance is poor and the cracking limit moisture absorption time is short. On the other hand, in all cases, the flexural strength of the cured epoxy resin composition is 0.60 k.
g / mm ² or more, flexural modulus of 65 kg / mm ² or less,
Saturated water absorption is 0.40% or less and Df ₃₀ is 6.0
^{X10 -7} mm ² / sec or less, Df ₈₅ is 5.0 x 10 ^-6
mm ² / sec or less, further examples article Df ₈₅ / Df ₃₀ is less than 10 has a high adhesive strength, excellent and longer limit moisture absorption time in moisture resistance. Therefore, it can be seen that the products of Examples are excellent in moisture resistance reliability and low in stress at high temperature.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view for explaining a situation where a package crack occurs in a conventional semiconductor device.

FIG. 2 is a vertical cross-sectional view for explaining how a package crack occurs in another conventional semiconductor device.

FIG. 3A is a plan view illustrating a method for measuring an adhesive force between a semiconductor element and a cured product of an epoxy resin composition in Examples and Comparative Examples, and FIG. 3B is a front view thereof.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toku Nagasawa 1-2 1-2 Shimohozumi, Ibaraki-shi, Osaka Within Nitto Denko Corporation (72) Tsutomu Nishioka 1-2 1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Co., Ltd. (72) Inventor Tatsushi Ito 1-2-1, Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Denko Corporation

Claims (1)

[Claims] 1. An EPO having the following characteristics (a) to (d):
The semiconductor element is encapsulated by the cured product of the xy resin composition.
Semiconductor device. (A) The bending strength of the cured product is 0.6 kg / m at 260 ° C.
m²that's all. (B) The flexural modulus of the cured product is 65 kg / m at 260 ° C.
m²Less than. (C) Saturated water absorption of the cured product is 85 ° C./85% RH atmosphere
0.4% by weight or less in the air. (D) Diffusion coefficient (Df of cured product at 30 ° C.)₃₀)But,
Df₃₀= 6.0 × 10 ^-7mm²/ Sec or less, 85 ° C
Diffusion coefficient (Df₈₅) Is Df₈₅= 5.0 x 10
^-6mm²/ Sec or less and the diffusion coefficient Df₃₀
And Df₈₅An epoxy whose ratio of satisfies the following inequality
Cured product of resin composition. Df₈₅/ Df₃₀<10.0