JPH03154368A - Semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a semiconductor device excellent in stress resistance capable of withstanding the heating in mounting with solder and besides abundant in the moisture resistance reliability after mounting with solder by specifying the flexural strength of the hardening body of an epoxy resin composition hardening body, the flexural modulas of elasticity of the hardening body, the saturated water absorption coefficient of the hardening body, and the diffusion coefficient at 30 deg.C. CONSTITUTION:A semiconductor element is sealed with an epoxy resin composition hardening body, wherein the flextural strength is 0.6kg/mm<2> or more at 260 deg.C, the flexural modulas of elasticity is 65kg/mm<2> at 260 deg.C, the saturated water absorption coefficient is 0.4wt.% or less in 85 deg.C/85%RH atmosphere, the diffusion coefficient (Df30) at 30 deg.C is Df30=6.0X10<-7>mm<2>/sec or less, and the diffusion coefficient (Df85) is Df85=5.0X10<-16> mm<2>/sec or less, and besides the ratio of the diffusion coefficient Df30 to Df85 meets the formula 1. Hereby, even under the severe condition in mounting with solder, it never gives rise to package cracks, thus it becomes the one provided with excellent moisture resistance reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor device having excellent moisture resistance.

[Background Art] Semiconductor elements such as transistors, ICs, and LSIs are sealed with plastic packages and the like to form semiconductor devices from the viewpoint of protecting the external environment and enabling handling of the elements. A typical example of this type of package is a dual in-line package (DIP). This DIP is of a bottle insertion type, and a semiconductor device is attached by inserting a bottle into a mounting board.

Recently, the integration and speed of semiconductor devices such as LSI chips have been increasing, and in addition, the demand for smaller and more highly functional electronic devices has led to higher density packaging. From this point of view, surface mount packages have become mainstream instead of pin insertion type packages such as DIP. In a semiconductor device using this type of package, pins are taken out in a plane and fixed directly to the surface of the mounting board by soldering or the like. These surface-mount semiconductor devices have the advantage of being thin, light, and small because they can be removed from the bin flatly, and therefore occupy a small area on the mounting board. In addition to this, it also has the advantage of being able to be mounted on both sides of the board.

[Problem to be solved by the invention]

However, in a semiconductor device using a surface mount package as described above, if the package itself absorbs moisture before surface mounting, the problem arises that the package cracks due to the vapor pressure of the moisture during solder mounting. . That is, in a surface-mounted semiconductor device as shown in FIG. 1, moisture generally enters the package 3 through the sealing resin 1 as shown by arrow A, and mainly penetrates the surface of the Si-chip 7 and the die bond pad. It accumulates on the back side of 4. Then, when performing solder surface mounting by paper phase soldering or the like, the accumulated moisture is vaporized by the heating during the solder mounting, and the pressure causes the back surface of the Guibond pad 4 to The resin part of the package 3 is pushed downward to create a gap 5 there, and at the same time the package 3
A crack 6 is generated in the In FIGS. 1 and 2, 8 is a bonding wire.

As a solution to these problems, there are methods in which the semiconductor element is sealed in a package, the resulting semiconductor device is then packaged in a moisture-proof package, and the package is opened and used immediately before surface mounting, or the semiconductor device is packaged immediately before surface mounting. A method was proposed in which the material was dried at 100°C for 24 hours and then solder mounted.
Already implemented. However, according to such a pretreatment method, there is a problem that the manufacturing process is long (and labor-intensive).

On the other hand, in order to realize low moisture absorption of the encapsulating resin, an epoxy resin composition for semiconductor encapsulation is prepared using, for example, an epoxy resin having a skeleton represented by the following general formula (IV) and an epoxy resin having a skeleton represented by the following general formula (IV). An epoxy resin composition containing a novolak resin represented by V) has been proposed.

) However, when a semiconductor element is encapsulated using the above-mentioned epoxy resin composition, although the moisture absorption rate of the encapsulating resin is reduced, the moisture resistance after solder mounting is deteriorated.

This invention was made in view of these circumstances, and does not require pretreatment when mounted on electronic equipment, has excellent low stress properties that can withstand heating during solder mounting, and has excellent moisture resistance after solder mounting. The purpose is to provide a semiconductor device with high flexibility.

[Means to solve the problem]

In order to achieve the above object, the semiconductor device of the present invention includes:
The structure is such that a semiconductor element is sealed with a cured epoxy resin composition having the following characteristics (a) to (d).

(a) The bending strength of the cured product is 0.6 kg/at 260°C.
ff1Il! that's all.

(b) The flexural modulus of the cured product is 65 kg at 260"C
/m” or less.

(c) The saturated water absorption rate of the cured product is -85°C/85%RH
0.4% by weight or less in an atmosphere.

(d) The diffusion coefficient (Df30) at 30°C of the cured body is D f 30-6,OX 10-'ai''/se
c or less, the diffusion coefficient (Df, ) at 85°C is I
) r85=5. Oxl O-'tm''/sec or less, and the ratio of the diffusion coefficients Dr30 and Dr, , satisfies the following inequality.

Df-s/Dfy. < 10.0 [Function] According to the present invention, it is possible to
It is possible to significantly improve the package crack resistance and moisture resistance of the sealing resin at temperatures of 15 to 260°C.

In order to obtain the semiconductor device of the present invention, for example, the following (A
) and (B) components may be used to seal the semiconductor element.

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

(B) a silane compound represented by the following general formula (n);
A reaction product obtained by preliminary reaction with a phenol aralkyl resin represented by the following general formula (I[I).

(X+-TSi +Y) s-...(II) The epoxy resin composition used in the second invention is obtained using the above-mentioned epoxy resin and a curing agent, and is usually a powder. or compressed into tablets.

The above-mentioned epoxy resin is not particularly limited, and commonly used epoxy resins may be used. Among these, for example, a biphenyl type epoxy resin represented by the following general formula (1) is preferably used.

(Margin) In this way, the epoxy resin obtained by substituting a lower alkyl group on the aromatic ring having a glycidyl ether group has brine properties. The epoxy resin component may be composed only of the special epoxy resin represented by the above general formula (1), or may be used in combination with other commonly used epoxy resins. In the former case, the entire epoxy resin is composed of the special epoxy resin of the above general formula (1), and in the latter case, a part of the epoxy resin is composed of the special epoxy resin of the above general formula (I). The Rukoto. Examples of the above-mentioned commonly used epoxy resins include various epoxy resins such as cresol novolak 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 250. Those with a softening point of 50 to 130°C are used, and as Talesol novolac type epoxy resins, epoxy equivalents are 180 to 180.
210. Those having a softening point of 60 to 110°C are generally used. When using both together in this way, the above general formula (
It is preferable that the epoxy resin represented by I) accounts for 20% by weight or more (hereinafter abbreviated as "%") of the entire epoxy resin component, particularly preferably 50% or more.

The above curing agent is a special curing agent obtained by pre-reacting a specific silane compound represented by the following general formula (n) and a specific phenol aralkyl resin represented by the following general formula (■). A reaction product is used.

(X 5i-fY) 3-...(II) (margin) In other words, the above-mentioned special reaction product is expressed by the above-mentioned general formula (n)
It is obtained by reacting the organic group X and the alkoxy group Y of a specific silane compound represented by the formula (■) with the OH group in the specific phenol aralkyl resin represented by the general formula (■), and performing dealcoholization.

As the specific silane compound represented by the above general formula (II), commonly used silane coupling agents are used, 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-()rimethoxysilyl)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)triethylenetetraamine, N-3-trimethoxysilylpropyl-m-phenylenediamine, and the like.

The specific phenolic aralkyl resin represented by the general formula (I[I) above can be obtained by reacting an aralkyl ether with a phenol using a free sol fluorine catalyst. In general, phenol aralkyl resins include α, α
Condensation polymer compounds of '-dimethoxy p-xylene and phenol monomers are known. As the above-mentioned phenol aralkyl resin, it is preferable to use one having a softening point of 70 to 110° C. and a dihydroxyl equivalent of 150 to 220. Moreover, the above-mentioned phenol aralkyl resin may be used in combination with a commonly used phenol resin.

Examples of the above-mentioned commonly used phenolic resins include phenol novolac and talesol novolac.

These novolac resins have a softening point of 50 to 110.
It is desirable to use one having a hydroxyl equivalent of 70 to 150 at °C. When the above-mentioned phenol aralkyl resin and such a normal phenol resin are used together, it is preferable to set the above-mentioned phenol aralkyl resin at a ratio of 50% or more of the total amount of the phenol aralkyl resin and the normal phenol resin, Particularly preferably, it is 70% or more.

The blending ratio of the preliminary reaction product is preferably such that the amount of hydroxyl group in the preliminary reaction product is 0.7 to 1.3 equivalents per equivalent of epoxy group in the epoxy resin.

More preferred is 0.8 to 1.2 equivalents.

A special reaction product consisting of the above-mentioned specific silane compound and a specific phenol aralkyl resin can be 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 stirring device, and the temperature is raised to 120 to 180°C, particularly preferably 130 to 150°C, so that the two react with each other to form a reaction product. Create. Next, the alcohol produced in this reaction is removed from the yarn by degassing or the like at a temperature 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 includes a flame retardant, wax, etc. as necessary.

Examples of the inorganic filler include crystalline and fusible silica. The amount of this inorganic filler added is preferably set to 65% or more of the total epoxy resin composition. Particularly preferred is 70% or more. That is, if the blending amount of the inorganic filler is less than 65%, the bending strength at 260° C. after saturated moisture absorption of the obtained cured epoxy resin composition decreases (less than 0.60 kg/mm 2 ).

The curing accelerators mentioned above include amine type and phosphorus type.

Curing accelerators such as boron type and phosphorus-boron type are mentioned,
Used alone or in combination.

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

The above-mentioned coupling agents include glycidyl ether type, amine type, and thiocyan type.

Methoxy or ethoxysilane such as urea type,
They may be used alone or in combination as appropriate.

It can be used in any manner, such as by triblending or preheating the filler, or by premixing the organic component raw material.

Examples of the 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 addition to the above-mentioned additives, the epoxy resin composition used in the present invention is blended with rubber components such as silicone oil, silicone rubber, and synthetic rubber to reduce stress and improve reliability in moisture resistance tests. For the purpose of improvement, an ion trapping agent such as hydrotalcite may be added.

The epoxy resin composition used in the present invention can be produced in the following manner, 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, this reaction product and the above-mentioned epoxy resin are suitably blended and premixed, and then kneaded in a heated state using a kneading machine such as a mixing roll machine to melt-mix, and after cooling to room temperature, by known means. It can be manufactured through a series of steps of pulverizing and, if necessary, tableting.

The encapsulation of a semiconductor element using such an epoxy resin composition is not particularly limited, and can be performed by a known molding method such as ordinary transfer molding. In the present invention, by molding a semiconductor element using the above-mentioned epoxy resin composition, a semiconductor device sealed with a cured product satisfying the physical properties (a) to (d) above can be obtained. Can be done.

In this invention, the bending strength of the cured product (a) is 0.
．． If it is less than 6 kg/mm", cracks will occur in the package. In addition, the flexural modulus of (b) exceeds 65 kg/w", the saturated water absorption rate of (c) exceeds 0.4%, and the Df3o of (d) 6. Exceeds OX 10-'rNM"/sec, Df85 is 5.OX 10-7mm2/s
eC, and the above-mentioned diffusion coefficients Df30 and Dr8
, the ratio (D f +15/D f 30) is 10.0
This is because, if a material having the above characteristics is used, the crack resistance will also be reduced.

Usually, as the above epoxy resin composition, (a) the bending strength of the cured product is 0.6 to 1.5 kg / 260 ° C.
rm'', (b) the flexural modulus of the cured product is 26
Within the range of 30 to 65 kg/m² at 0°C, (c) the saturated water absorption rate of the cured product is less than the above value (the lower the better), and (d) the diffusion coefficient at 30°C of the cured product ( D f *o) and a diffusion coefficient at 85° C. (D85) that satisfy the above values are used. Further, the adhesive strength between the cured product and the semiconductor element is usually 2 kg/mu" or more, preferably 3 kg/mm" or more, - 2 to 8 mu for boat fishing.
It is said to be about kg/M2.

The above bending strength and bending elastic modulus were measured at 260° C. after preparing a cured product of the epoxy resin composition.

This is a value obtained by conducting a test according to JIS-6911.

In addition, the above saturated water absorption rate was determined by transferring the obtained epoxy resin composition to a diameter of 50III11.
．． After hardening and molding into a 3M thick disk, 85'C/85
This value is obtained by absorbing moisture for 500 hours in an atmosphere of %RH. The conditions for the above-mentioned curing molding are 175°C and 2 minutes for normal epoxy resin.

After-cure: 175° C., 5 hours at 70 kg/d.

Further, each of the above-mentioned diffusion coefficients Df30 and Df85 is a value calculated by substituting the amount of water absorbed by the cured body into the following equation, which corresponds to short-time moisture absorption in flat plate moisture absorption in Fickian diffusion.

The semiconductor device obtained in this way is resin-sealed with a cured epoxy resin composition having the above-mentioned characteristics, so it has excellent moisture resistance and reliability, and does not cause package cracks etc. even when soldered. do not have.

〔Effect of the invention〕

As described above, in the semiconductor device of the present invention, a semiconductor element is resin-sealed with a special epoxy resin composition whose cured product has a predetermined bending strength, flexural modulus, saturated water absorption, and diffusion coefficient. It has been obtained. Therefore, this product does not cause package cracks even under severe conditions such as solder mounting, and has excellent moisture resistance reliability. In particular, it has high reliability and is optimal for surface mounting of thin flat packages.

The special epoxy resin composition may include a special epoxy resin represented by the general formula (1), a silane compound represented by the general formula (It), and a silane compound represented by the general formula (In). It is particularly effective to use epoxy resin compositions obtained using pre-reaction products with phenolic aralkyl resins.

Next, examples will be described together with comparative examples.

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

(Left below) Next, the phenolic resins C, D and silane compounds E, F, and G in Table 1 above were mixed in the proportions shown in Table 2 below, and the mixture was poured into a reaction vessel equipped with a stirring device. The reaction product J-N was prepared by preliminarily reacting under the reaction conditions shown and degassing (170°C).

(Left below) [Examples 1 to 7, Comparative Examples 1 to 3] The above reaction products J-N, epoxy resins A and B, and other additives were blended in the proportions shown in Table 3 below, The mixture was kneaded using a mixing roll machine at 100° C. for 10 minutes to obtain a sheet-like composition.

Then, the obtained sheet-like composition was pulverized to obtain the desired powdered epoxy resin composition.

(The following is a blank space) Next, a semiconductor device was obtained by molding a semiconductor element by transfer molding using the powdered epoxy resin composition obtained in Examples 1 to 7 and Comparative Examples 1 to 3. This semiconductor device is an 80-bin four-way flat package (QFP) (20 mm x 14 mm x 2.5 m thick).
m) with a Guipond plate of 7 mm x 7 mm and a chip size of 6.5 m x 6.5 mm. The thus obtained semiconductor device was immersed in solder at 260° C., and the critical moisture absorption time at 85° C./85% RH until package cracking occurred was measured. Further, using the above epoxy resin composition, a disk-shaped cured body with a thickness of 3 mm and a diameter of 50III11 was prepared (molding conditions: 175°C, 2 minutes, 70kg/cJ, after-cure: 175°C, 5 hours). The disk-shaped cured product was allowed to absorb moisture for 500 hours at 85° C. and 85% RH, and the saturated water absorption rate was measured.

Furthermore, the bending strength and bending elastic modulus of the cured product were determined according to JIS-
-6911, 5, 17 at 260°C. Then, the adhesive strength between the semiconductor element and the cured product was measured. On the other hand, the diffusion coefficient D of the epoxy resin composition at 30°C
Diffusion coefficient D f 8 at rff 30 and 85°C
5 was measured according to the above formula. These results are shown in Table 2 below.

In addition, the said adhesive force was measured as follows. That is, using the above epoxy resin composition, as shown in FIGS. 3(A) and (B), a truncated cone with an upper surface having a diameter a=l IM, a lower surface having a diameter b=9 u, and a height h=10+nm was formed. A truncated cone-shaped cured product 10 is prepared, and this truncated conical cured product 10 is
A semiconductor element 11 with a size of 2 mm x 2 mm x 0.4 plate in thickness was mounted at the center of the upper surface of the device. And this truncated conical cured product 10
The shear bond between the semiconductor element 11 and the semiconductor element 11 was measured.

(Left below) From the results in Table 4, it can be seen that the flexural modulus of the cured epoxy resin composition exceeds 65kg10n'', and Df @-,
/ D' f 30 exceeds 10, 1 comparative example, bending strength is less than 0.6 kg/w'', bending modulus is 65
The four products of Comparative Examples that exceed the moisture absorption limit for cracking are all short in moisture absorption time, which exceeds the moisture absorption limit for cracking.In addition, the two comparative examples use normal phenolic resin, so they have inferior moisture resistance and have a moisture absorption time that exceeds the moisture absorption limit for cracking. In contrast, the bending strength of the cured epoxy resin composition is 0.
．． 60 kg/mm” or more, flexural modulus is 65 kg
/mm" or less, saturated water absorption rate is 0.40% or less, D'fao is 6.OX 10-7mm2/sec or less, and D f Ils is 5.0 X 10-7mm2/s.
Below e c, further D85/D f 30 is 10
Products with a bonding strength of less than 100% have high adhesive strength, excellent moisture resistance, and a long silver interface moisture absorption time. Therefore, it can be seen that the practical products have excellent moisture resistance reliability and low stress properties at high temperatures.

[Brief explanation of the drawing]

FIGS. 1 and 2 are longitudinal cross-sectional views illustrating the occurrence of package cracks in conventional semiconductor devices, and FIG. Plan view explaining the adhesive force measurement method, 3rd
Figure (B) is its front view.

Claims (1)

[Claims] (1) A semiconductor device in which a semiconductor element is encapsulated with a cured epoxy resin composition having the following characteristics (a) to (d). (a) The bending strength of the cured product is 0.6 kg/m at 260°C
More than m^2. (b) The flexural modulus of the cured product is 65 kg/m at 260°C
m^2 or less. (c) The saturated water absorption rate of the cured product is 0.4% by weight or less in an atmosphere of 85° C./85% RH. (d) Diffusion coefficient of the cured product at 30°C (Df_3_0
) is Df_3_0=6.0×10^-^7mm^2/
sec or less, the diffusion coefficient (D_8_5) at 85℃ is Df_8_5=5, 0×10^-^6
mm^2/sec or less, and the ratio of the above-mentioned diffusion coefficients Df_3_0 and Df_8_5 satisfies the following inequality. Cured epoxy resin composition Df_8_5/Df_3_0<10.0