JP2519280B2 - Semiconductor device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device in which package cracks are less likely to occur during surface mounting.

[Conventional technology]

Semiconductor elements such as transistors, ICs, and LSIs are made into semiconductor devices by being sealed with a plastic package or the like from the viewpoints of protecting the external environment and enabling the handling of the elements. A representative example of this type of package is a dual in-line package (DIP). The DIP is of a pin insertion type, and attaches a semiconductor device by inserting a pin into a mounting board.

Recently, high integration and high speed of semiconductor devices such as LSI chips have been advanced, and in addition, high density mounting has been advanced due to a demand for making electronic devices small and highly functional. From this point of view, instead of a pin insertion type package like DIP,
Surface mount packages are becoming mainstream. In a semiconductor device using this kind of package, pins are taken out in a plane and are fixed directly to the surface of the mounting board by soldering or the like. Such a surface-mount type semiconductor device has an advantage that pins can be taken out in a plane and has the advantages of being thin, light, and small, and therefore has the advantage of occupying a small area on the mounting board. In addition, it has the advantage that double-sided mounting on a substrate is also possible.

[Problems to be solved by the invention]

However, in a semiconductor device using a surface mounting package as described above, when the package itself absorbs moisture before surface mounting, there is a problem that cracking occurs in the package due to water vapor content during solder mounting. is there.
That is, in the surface mount type semiconductor device as shown in FIG. 1, moisture enters the package 3 through the sealing resin 1 and the gap between the lead frame 2 and the resin 1 as shown by arrow A. , Mainly on the back surface of the die bond pad 4 of the lead frame 2. Then, when solder surface mounting such as vapor phase soldering is performed, the accumulated water is vaporized by heating in the solder mounting, and the vapor pressure thereof causes the die bond pad 4 as shown in FIG.
The resin portion on the back surface of the package 3 is pushed downward to create a gap 5 therein, and at the same time, to generate a crack 6 in the package 3.
1 and 2, reference numeral 7 denotes a semiconductor element, and reference numeral 8 denotes a wire bonding.

As a solution to such a problem, after sealing a semiconductor element in a package, the obtained semiconductor device is hermetically sealed, and opened and used just before surface mounting. A method of drying at 100 ° C. for 24 hours and then performing solder mounting has been proposed and has already been implemented. However, according to such a pretreatment method, there is a problem that the manufacturing process becomes long and labor is required.

The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a semiconductor device which does not require pre-processing when mounted on an electronic device and which is excellent in low stress property that can withstand heating during solder mounting. I do.

[Means for solving problems]

In order to achieve the above object, the semiconductor device of the present invention has an epoxy resin main component (component A) at least a part of which is an epoxy resin represented by the following general formula (I).
And a phenol resin curing agent component (B component) composed of a phenol resin represented at least in part by the following general formula (II) and an inorganic filler (C component) as main components, and the following general formula (III ) And a silicone represented by (IV), at least one of which is reacted with at least one of the above-mentioned components A and B, or in a state as it is, a semiconductor device is manufactured. It is configured to be sealed.

In the above formulas (I) and (II), the number of repetitions n
Is determined from the weight average molecular weight Mw value.

(M + n = 2 to 200, where m and n are integers of 1 or more.) (L = 2 to 200, where l is an integer of 1 or more.) [Action] As a method of preventing the occurrence of package cracks,
Three methods are conceivable: suppression of moisture absorption with respect to the sealing resin, enhancement of the adhesive force between the back surface of the die bond pad and the surface of the semiconductor element and the sealing resin, and enhancement of the strength of the sealing resin itself. This invention prevents the occurrence of package cracks by increasing the strength of the encapsulating resin itself. The special epoxy resin represented by the general formula (I) and the general formula (II By using a special phenol resin represented by), the strength of the sealing resin at high temperature (215 ° C.) such as solder mounting is improved about 3 to 4 times as compared with the current resin. To do so. Further, by using the silicone represented by the general formulas (III) and (IV) together as the silicone in the epoxy resin composition used for encapsulation, the epoxy resin composition is imparted with a low stress property. .

The epoxy resin composition used in the present invention comprises an epoxy resin main component (A component) which is entirely or partially composed of a special epoxy resin represented by the general formula (I), and wholly or partly of the general formula (A). II) A phenolic resin hardener component (B component) consisting of a special phenolic resin
And an inorganic filler (component C) and at least one of the silicone represented by the general formula (III) and the silicone represented by (IV), and the like.
Usually, it is in the form of powder or a tablet formed by compressing it.

The special epoxy resin of the general formula (I) constituting all or a part of the above-mentioned epoxy resin main component has a structure in which phenyl glycidyl ether is bonded to a methylene group in the main chain of a novolak type epoxy resin. With such a molecular structure, the number of crosslinking points is increased and a structure having a high crosslinking density can be obtained. The epoxy resin main component may be composed of only the special epoxy resin described above, or may be used in combination with other commonly used epoxy resins. Examples of commonly used epoxy resins include various epoxy resins such as cresol novolak type, phenol novolak type, novolak bis A type and bisphenol A type. Among these resins, it is preferable to use a resin having a melting point exceeding room temperature and exhibiting a solid state or a highly viscous solution state at room temperature. Novolak type epoxy resin is usually
A resin having an epoxy equivalent of 150 to 250 and a softening point of 50 to 130 ° C is used. As the cresol novolak type epoxy resin, a 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 this manner, the special epoxy resin represented by the general formula (I) and the ordinary epoxy resin are used in an amount of 100 parts by weight (hereinafter abbreviated as "part") with respect to the former. The latter is preferably set within the range of 0 to 100 parts.

The special phenol resin represented by the above general formula (II), which constitutes all or part of the phenol resin curing agent component, has a structure in which a phenol is bonded to the methylene group of the main chain of the phenol novolak, Due to such a molecular structure, the number of cross-linking points increases, whereby a three-dimensional structure having a high cross-linking density can be obtained. The above-mentioned special phenol resin may constitute the phenol resin curing agent component by itself, or may be used in combination with other commonly used phenol resin. Examples of other phenol resins include phenol novolak and cresol novolak. It is desirable that these novolak resins have a softening point of 50 to 110 ° C. and a hydroxyl group equivalent of 70 to 150. Particularly, of the above-mentioned novolak resins, it is possible to obtain good results by using cresol novolak. When the special phenol resin represented by the general formula (II) and such a normal phenol resin are used in combination, the ratio of the both is 100 parts of the former and 0 to 100 of the latter.
It is preferable to set it within the range of the parts in terms of the effect.

C used together with the epoxy resin main component as the component A and the phenol resin curing agent as the component B
Examples of the inorganic filler as a component include not only crystalline and fusible fillers but also aluminum oxide, beryllium oxide, silicon carbide, silicon nitride and the like.

As the silicone used together with the epoxy resin main ingredient component which is the A component, the phenol resin curing agent component which is the B component, and the inorganic filler which is the C component, those represented by the above general formula (III) and (IV) At least one of those represented is given, and a typical example thereof is
Both ends epoxy dimethyl siloxane, side chain epoxy dimethyl siloxane, both ends diamine dimethyl siloxane,
A side chain diamine dimethyl siloxane is mentioned. Such silicone may be used as it is, or may be used by pre-reacting with the above-mentioned components A and B. In this case, the amount of the silicone used is in the range of 3 to 40% by weight (hereinafter abbreviated as "%") with respect to the organic component (excluding the inorganic filler from the epoxy resin composition) in the epoxy resin composition. It is preferable to set to. More preferred is 5 to 20%. That is, when the content of the silicone is less than 3%, a sufficient low stress effect cannot be obtained, and when it exceeds 40%, the mechanical strength of the resin is decreased. It is also effective to reduce the stress by dry-blending the silicone rubber particles.

In the epoxy resin composition used in the present invention, a flame retardant, a coupling agent, a curing accelerator, wax, etc. may be used, if necessary, in addition to the above components.

As the flame retardant, a compound such as a novolak-type brominated epoxy or a bis-A-type epoxy, antimony trioxide and antimony pentoxide may be appropriately used alone or in combination.

As the above-mentioned coupling agent, methoxy or ethoxysilane such as glycidyl ether type, amine type, thiocyan type and urea type may be used alone or in combination as appropriate. 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 curing accelerator include amine-based, phosphorus-based, and boron-based curing accelerators, which may be used alone or in combination.

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.

The epoxy resin composition used in this invention can be produced, for example, as follows. That is, after appropriately mixing and premixing the above component raw materials, the mixture is kneaded in a heating state by a kneading machine such as a mixing roll machine to be melt mixed, cooled to room temperature, and then pulverized by a known means, It can be manufactured by a series of steps of tableting as necessary.

The sealing of the semiconductor element using such an epoxy resin composition is not particularly limited, and can be performed by a known molding method such as normal transfer molding.

The semiconductor device thus obtained includes a special epoxy resin (component A) represented by the general formula (I) and a special phenol resin represented by the general formula (II) contained in the epoxy resin composition. (Component B) and the above general formula (III)
Due to the action of the special silicone represented by (4) and (IV), the strength of the sealing resin, especially at high temperature, is 3 to 4 times higher than that of the conventional one, and it has excellent low stress properties. Therefore, package cracking does not occur during solder mounting.

〔The invention's effect〕

In the semiconductor device of the present invention, the semiconductor element is resin-encapsulated by using the special epoxy resin composition containing the special epoxy resin, the phenol resin and the silicone as described above. No package crack occurs even under conditions. In particular, by sealing with the above special epoxy resin composition,
8 pins or more, especially 16 pins or more or the long side of the chip is 4 m
The above high reliability can be obtained in a large-sized semiconductor device having a size of m or more, which is a major feature.

 Next, examples will be described together with comparative examples.

[Examples 1 to 10, Comparative Examples 1 to 5] First, component raw materials used in Examples and Comparative Examples are as follows.

<< Main ingredient >> A: Component of general formula (I) (n = 3) B: Epoxycresol novolak (n = 4) (where n is calculated from the weight average molecular weight of polystyrene-converted GPC data and the distribution itself is wide << Curing agent >> C: Component of general formula (II) (n = 3) D: phenol novolak (n = 4) (where n is calculated from the weight average molecular weight of polystyrene-converted GPC data) Distribution itself is wide range.) << Filler >> E: Maximum particle size = 150 μm, average particle size = 20 μm, shape = crushed SiO
₂ << Flame Retardant >> F: Novolac type Br epoxy epoxy G: Antimony trioxide << Curing catalyst >> H: Dimethylimidazole << Release agent >> I: Polyethylene wax << Additive >> J: Trimethoxysilaneglycidyl ether << Silicone Modifier >> K: Structure represented by general formula (III), X is glycidyl ether, average molecular weight is 10,000, and epoxy equivalent is 5000.

L: structure represented by general formula (IV), X is amine, average molecular weight
12000, epoxy equivalent 6000.

<< Modification Method >> (a) A is preliminarily reacted.

(B) Perform preliminary reaction on B.

(C) Preliminary reaction is performed on C.

(D) Perform a preliminary reaction to D.

<< Reaction conditions in denaturing method >> (e) Temperature 175 ° C, stirring for 5 hours, stirring reaction.

(F) Temperature 175 ° C., stirring for 2 hours, stirring reaction.

The raw materials shown in Table 1 below are blended in the proportions shown in the table,
The mixture was kneaded with a mixing roll machine at 100 ° C. for 10 minutes to obtain a sheet composition. Then, the obtained sheet-shaped composition was pulverized to obtain a desired powdered epoxy resin composition.

A semiconductor device was obtained by molding a semiconductor element by transfer molding using the powdery epoxy resin compositions obtained in the above Examples and Comparative Examples. This semiconductor device is an 80-pin QFP package (20 x 14 mm, thickness 2.
25 mm) and has a chip size of 7 × 7 mm.

The semiconductor device thus obtained was subjected to a measurement test. The results are shown in Table 2 below.

From the results in Table 2, the example products are not so different from the comparative example in each property, especially in the bending property at room temperature (RT),
At a high temperature such as 215 ° C., the result is remarkably superior to that of the comparative example, and it can be seen that the strength of the package at a high temperature is significantly improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 and FIG. 2 are explanatory views of a conventional example.

Claims (1)

(57) [Claims] 1. An epoxy resin main component (A) at least partially composed of an epoxy resin represented by the following general formula (I):
Component), a phenol resin curing agent component (B component) composed of a phenol resin represented at least in part by the following general formula (II), and an inorganic filler (C component) as main components. A semiconductor is obtained by using an epoxy resin composition containing at least one of the silicone represented by (III) and the silicone represented by (IV) in a state of reacting with at least one of the above-mentioned components A and B or in the state as it is. A semiconductor device in which elements are sealed. (M + n = 2 to 200, where m and n are integers of 1 or more.) (L = 2 to 200, where l is an integer of 1 or more.)