JPH03116952A - Semiconductor device - Google Patents

Abstract

PURPOSE:To improve a semiconductor device in package crack resistance at a high temperature on solder-mounting of a semiconductor element by a method wherein the semiconductor element is sealed up with epoxy resin composition composed of a main component of epoxy resin and a setting agent component which is, at least, partially formed of specific phenolic resin. CONSTITUTION:A semiconductor device is composed of a sealing resin 1, a lead frame 2, a package 3, a die bonding pad 4, a semiconductor element 7, and a bonding wire 8. The semiconductor element 7 is sealed up with epoxy resin composition composed of a main component of epoxy resin and a setting agent component which is, at least, partially formed of phenolic resin represented by a formula I. In the formula I, m/n is 1 or more, and m+n is an integer of 2-15. As mentioned above, the epoxy resin composition sealing resin 1 is made small in moisture absorption, whereby the package 3 can be improved in moisture resistance. By this setup, a semiconductor device of this design can be improved in package crack resistance at a high temperature on solder-mounting.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor device that has excellent moisture resistance and reliability, and particularly excellent crack resistance during solder mounting.

[Conventional technology]

Semiconductor elements such as transistors, ICs, and LSIs are sealed in ceramic packages, plastic packages, and the like to form semiconductor devices. Among these, resin encapsulation using a plastic package has become the mainstream for semiconductor packages because it is excellent in mass production and the encapsulation material is inexpensive. Epoxy resin compositions have conventionally been used as materials for this type of plastic package. The above-mentioned epoxy resin composition has excellent electrical properties, mechanical properties, chemical resistance, etc., and is therefore highly reliable and widely used for resin encapsulation of semiconductor devices. The above-mentioned epoxy resin composition is particularly composed of an 0-talesol novolac epoxy resin, a phenol novolac resin as a curing agent, a tertiary amine as a curing accelerator, and fused silica as an inorganic filler. , has been awarded for its excellent sealing workability (especially workability during transfer molding).

However, technological innovation in the semiconductor field is remarkable, and in recent years, improvements in the degree of integration have led to higher functionality and faster speeds.In addition, the demand for smaller and more functional electronic devices has led to higher density packaging. There is. From this point of view, surface mount packages have become mainstream in place of pin insertion type packages such as dual in-line packages (DIPs). 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. Such a surface-mounted semiconductor device can be removed from the bottle on a flat surface, and has the advantages of being thin, light, and small.

Therefore, it has the advantage that it occupies only a small area on the mounting board and can also 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, there is a problem that cracks occur in the package due to the vapor pressure of moisture during solder mounting. That is, in a surface-mounted semiconductor device as shown in FIG. It accumulates on the back side. Then, when performing solder surface mounting such as paper phase soldering, the accumulated moisture is vaporized by the heating during the solder mounting, and its vapor pressure causes the resin on the back side of the die bond pad 4 to be heated as shown in FIG. The part is pushed downward, creating a gap 5 there and at the same time creating a crack 6 in the package 3. In FIGS. 1 and 2, 7 is a semiconductor element and 8 is a wire bonding.

As a solution to such problems, there are methods in which the semiconductor element is sealed in a package, the entire semiconductor device obtained is sealed, and the package is opened and used immediately before surface mounting, or the semiconductor device is sealed in a package immediately 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, such a pretreatment method lengthens the manufacturing process and is labor-intensive. There is.

This invention was made in view of the above circumstances, and its purpose is to provide a semiconductor device that does not require pre-treatment when mounted on electronic equipment and has excellent low stress properties that can withstand heating during solder mounting. shall be.

[Means to solve the problem]

In order to achieve the above object, the semiconductor device of the present invention includes:
A semiconductor element is manufactured using an epoxy resin composition containing an epoxy resin base component (component A) and a phenolic resin curing agent component (component B), at least a part of which is made of a phenolic resin represented by general formula (I). It is configured to be sealed.

[Effect]

As a method to prevent the occurrence of package scratches,
Three methods can be considered: suppressing moisture absorption into the sealing resin; (1) increasing the adhesive force between the back surface of the Guibond pad and the surface of the semiconductor element and the sealing resin; and (2) increasing the strength of the sealing resin itself. The present invention is intended to improve the moisture resistance of a package by suppressing moisture absorption into an epoxy resin composition-based sealing resin mainly based on method (1) above. Therefore, the above − format (
It uses a special phenolic resin represented by 1), which allows it to withstand high temperatures (21
It is possible to realize a significant improvement in the package crack resistance of the sealing resin at a temperature of 5 to 260°C.

The epoxy resin composition used in this invention consists of an epoxy resin main component (component A) and a phenolic resin curing agent component (component B), which is entirely or partially composed of a special phenolic resin represented by the above-mentioned format (I). It is usually obtained in the form of a powder or a tablet made by compressing it.

Examples of the epoxy resin base component of component A include various epoxy resins such as cresol novolak type, phenol novolac type, novolac bis A type, and bisphenol A type epoxy resin. In particular, novolac type epoxy resins usually have an epoxy equivalent of 150 to 250.
．． Those with a softening point of 50 to 130°C are used, and the Talesol novolac type epoxy resin has an epoxy equivalent of 1
80-210. Those with a softening point of 60 to 110"C are generally used. Furthermore, it is more effective to use biphenyl-type epoxy resins such as 4,4'-bis(glycidyloxy)-3,3'-diallylbiphenyl. be.

The phenolic resin curing agent component of component B acts as a curing agent for the epoxy resin main component of component A, and is a special compound of general formula (1) below that constitutes all or part of the phenolic resin curing agent component. A phenolic resin can be obtained by reacting a phenol novolac with an allyl cloid.

Note that the m and n numbers in the above-mentioned format (1) are determined from the allyl group and the weight average molecular weight.

The above-mentioned special phenol resin may form a phenol resin curing agent component by itself, or may be used in combination with other commonly used phenol resins. In the former case, all of the B component is composed of the above-mentioned special phenolic resin of type (I), and in the latter case, a part of the B component is composed of the above-mentioned special phenolic resin of the above-mentioned type (1). The Rukoto. Examples of the above-mentioned commonly used phenolic resins include phenol novolac and talesol novolac. These novolak resins have a softening point of 50 to 110'C and a hydroxyl equivalent of 70 to 15
It is preferable to use 0. When the special phenolic resin represented by the above-format (1) and such a normal phenolic resin are used together, the ratio of both is:
100 parts by weight of the former (hereinafter abbreviated as "parts") to 0 of the latter
From the viewpoint of effectiveness, it is preferable to set the amount within the range of 100 parts to 100 parts.

The blending ratio of the epoxy resin base component (component A) and the phenolic resin curing agent component (component B) is such that the proportion of hydroxyl groups in component B is 0.5 to 2.0 per equivalent of epoxy group in component A.
It is suitable to mix so that it becomes 0 equivalent. More preferred is 0.8 to 1.2 equivalents.

Generally, an inorganic filler is used together with the epoxy resin main component (A component) and the phenol resin curing agent component (B component). Silica is usually used as the inorganic filler. In addition, crystalline and fusible silica as well as aluminum oxide,
Fillers such as beryllium oxide, silicon carbide, silicon nitride, etc. can be used. Such inorganic fillers include crushed fillers with a maximum particle size of 50 μm or less and an average particle size of 2 to 15 μm, and a crushed filler with a maximum particle size of 1100 μm or less.

From the viewpoint of effectiveness, it is preferable to use a spherical filler having an average particle size of 10 to 25 μm. By using both in combination in this way, it is possible to obtain approximately four times the strength compared to conventional sealing resins, and at the same time, it imparts excellent fluidity to the epoxy resin composition. . The content of this inorganic filler is 40 to 90% of the total epoxy resin composition.
It is preferable to set it within a range of % by weight.

The epoxy resin composition used in the present invention may contain flame retardants, coupling agents, curing accelerators, waxes, etc. in addition to the above-mentioned components A, B, and inorganic fillers, if necessary.

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 freely, such as tri-blending or preheating reaction with fillers, or premixing with organic component raw materials.

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

Examples include 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 suitably blending and pre-mixing the above-mentioned component raw materials, they are kneaded and melt-mixed in a heated state using a kneading machine such as a mixing roll machine, and after cooling this to room temperature, it is pulverized by known means, and as necessary. It can be manufactured by a series of steps of tabletting according to the appropriate conditions.

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 semiconductor device obtained in this way, the moisture absorption amount of the sealing resin is 7 times higher than that of the conventional one due to the action of the special phenolic resin of type (1) mentioned above contained in the epoxy resin composition.
Since it is reduced by ~80%, package cracks and the like will not occur during solder mounting.

[Effects of the Invention] As described above, the semiconductor device of the present invention is constructed by sealing a semiconductor element using a special epoxy resin composition containing the above-mentioned special phenol resin. Package cracks do not occur even under harsh conditions such as during solder mounting. In particular, by sealing with the above-mentioned special epoxy resin composition, the above-mentioned high reliability can be obtained in large semiconductor devices with 8 bottles or more, especially 16 pins or more, or a chip with a long side of 4 mm or more. This is a major feature.

Next, examples will be described together with comparative examples.

First, the raw materials used in Examples and Comparative Examples are shown below.

(Epoxy resin main component) A: Cresol novolac epoxy resin (epoxy equivalent: 195. Softening point: 80°C, n=4) (Phenol resin curing agent component) B: Phenol novolac (n=3) C: Above-format (I ), m=9. An allylated phenolic novolak resin where n=Q.

D: An allylated phenol novolak resin in the above-mentioned form (I), where m-10 and n=5.

E: In the above-format (1), m=7. An allylated phenolic novolac resin in which n=7.

(Inorganic filler) F: Molten SiO□ (shape = crushed type, maximum particle size = 50μ
Fog, average particle size = 15 μm) G: Melting 5in2 (shape = spherical, maximum particle size = 100
μm, average particle size = 20 μm) (Flame retardant) H: Novolak-type brominated epoxy I: Niantimony dioxide (hardening accelerator) J: 2-methylimidazole (mold release agent) K: Polyethylene wax (additive) ) L nitrimethoxysilane glycidyl ether [Example 1
~5. Comparative Example] Next, the raw materials shown in Table 1 below were blended in the proportions shown in the same table, and kneaded using a mixing roll machine at 100°C for 10 minutes to produce a sheet-like resin composition. Then, the sheet-like resin composition was pulverized to obtain the desired powdered epoxy resin composition.

(The following is a blank space) Using the powdered epoxy resin compositions obtained in Examples 1 to 4 and Comparative Examples 1 and 2, a semiconductor device was manufactured by molding a semiconductor element by transfer molding. The above semiconductor device is an 80-pin four-way flat package (QFP) (20 mm x 14 on x 2.25 m thick).
m) and 6. OX6. It has a chip of 0mm.

The semiconductor device obtained in this way was heated at 85°C.
After absorbing moisture for 72 hours under /85% RH, the number of package cracks generated when the package was immersed in solder for 10 seconds at 260°C was measured and shown in Table 2 below. In addition, the glass transition temperature (Tg) of the cured product of the epoxy resin composition was determined by TMA (The
mechanical analysis)
The bending strength at 250°C was measured according to JIS-
Measurement and evaluation were carried out by a bending test based on NI-6911.

Furthermore, a tablet with a diameter of 50 mm and a thickness of inn was prepared, and its water absorption rate was measured after 300 hours at 85°C/85% RH. These results are also shown in Table 2.

(Margin) From the results in Table 2, all of the sample semiconductor devices (10) have a high glass transition temperature but a high water absorption rate.
A package crack occurred.

On the other hand, the actual height measurements have high values for both glass transition temperature and bending strength, and also low water absorption. Furthermore, the number of package scratches occurring is smaller than in comparative height measurement. From this, it can be seen that the actual height measurement has excellent characteristics such as moisture resistance reliability and thermal shock resistance reliability.

[Brief explanation of drawings]

FIGS. 1 and 2 are vertical cross-sectional views illustrating the state of package racking in conventional semiconductor devices.

Claims (2)

[Claims] (1) Using an epoxy resin composition containing an epoxy resin base component (component A) and a phenolic resin curing agent component (component B), at least a part of which is composed of a phenolic resin represented by general formula (I). A semiconductor device made by sealing a semiconductor element. ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) [In the above formula (I), m/n is 1 or more and m+
n is an integer from 2 to 15. ] (2) An epoxy resin composition for semiconductor encapsulation containing an epoxy resin main component (component A) and a phenolic resin curing agent component (component B), at least a part of which is made of a phenolic resin represented by general formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) [In the above formula (I), m/n is 1 or more and m+
n is an integer from 2 to 15. ]