JPH03200357A - Semiconductor device - Google Patents

Abstract

PURPOSE:To eliminate preprocessing in surface mounting, to improve heat resistance upon mounting with solder, and to lower any stress by sealing a semiconductor device with an epoxy resin composition including phenol resin obtained by the copolycondensation of biphenol with specific biphenol, and epoxy resin. CONSTITUTION:A semiconductor device is sealed using an epoxy resin composition including phenol resin obtained by the copolycondensation of biphenol with phenol represented by formula I, and epoxy resin. In formula I, R is a hydrogen atom or a 1-4C hydrocarbon residue. Using such a phenol resin formed by the copolycondensation of biphenol as a hardener, preferably 4,4'-dihydroxy biphenol with the phenol represented by formula I, sealing resin is obtained which is low hygroscopic and has high glass transition temperature but a low linear expansion coefficient. Thus, preprocessing in surface mounting is eliminated and heat resistance upon mounting with solder is improved with any stress lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a highly reliable semiconductor device sealed with a sealing resin that has excellent mechanical strength at high temperatures.

[Conventional technology]

2. Description of the Related Art Semiconductor elements such as transistors, ICs, and LSIs are sealed in plastic packages or 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 pin insertion type, and a semiconductor device is attached by inserting pins 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. Such surface-mounted semiconductor devices have pins that can be taken out on a flat surface, and have the advantage of being thin, light, and small, and therefore occupy a small area on the mounting board. outside,
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, there is a problem that cracks occur in the package due to the vapor pressure of moisture during solder mounting.

As a solution to this problem, 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 heated at 100° just before surface mounting. Dry for 24 hours at C.
A method of subsequent solder mounting has been proposed and is already being implemented in some cases. However, such a pretreatment method has the problem that the manufacturing process becomes long and labor-intensive.

This invention was made in view of the above circumstances, and its purpose is to provide a semiconductor device that does not require pretreatment 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 configuration is adopted in which a semiconductor element is sealed using an epoxy resin composition containing an epoxy resin and a co-condensed phenol resin of biphenol and a phenol represented by the following general formula (1).

tt [Function] That is, the present inventors have conducted a series of studies in search of a sealing resin that is excellent in both moisture resistance and low stress properties. As a result, biphenol, preferably 4,4'-
It has been discovered that by using a co-condensed phenol resin of dihydroxybiphenyl and the phenol represented by the above general formula (1), a sealing resin with low hygroscopicity and a low coefficient of linear expansion despite a high glass transition temperature can be obtained. We have arrived at this invention.

The epoxy resin composition used in this invention consists of an epoxy resin (component A) and a special co-condensed phenol resin (component B).
It is usually obtained in the form of a powder or a tablet made by compressing it.

The epoxy resin as the component A is not particularly limited and may be appropriately selected from conventionally known epoxy resins depending on the purpose. Specifically, bisphenol A type epoxy resin, novolak phenol type epoxy resin, glycidylamine type epoxy resin, glycidyl ester type epoxy resin, cycloaliphatic epoxy resin, bisphenol S type epoxy resin, bisphenol F type epoxy resin, biphenol type epoxy resin. Examples include epoxy resins based on phenolic resins obtained by condensation reaction using aldehydes other than formalin. These may be used alone or in combination. Further, it is more effective to use a biphenyl type epoxy resin such as 4°4'-bis(glycidyloxy)-3,3'-diallylbiphenyl.

The special co-condensed phenol resin of component B acts as a curing agent for the epoxy resin of component A, and is produced by a co-condensation reaction using biphenol and a phenol represented by the following general formula (1). can get.

This special co-condensed phenolic resin has a rigid chemical structure (
The target is biphenol, which has a molecular structure (molecular structure) and improves the heat resistance of cured products, and is modified for the purpose of improving the compatibility of biphenol with epoxy resins and decomposability. Particularly preferred is one whose main component is a co-condensed phenol resin having a structure represented by the following formula (II) obtained by co-condensing O-cresol and biphenol.

The co-condensed phenol resin represented by the above structural formula (I[) has a structure in which the phenol of the above formula (I) is bonded to the 2.6-position and 2'6'-position of the biphenol skeleton via a methylene group. There is. However, depending on the reaction conditions, a structure may be formed in which biphenol is further bonded to biphenol via a methylene group, or the phenol of formula (I) bonded in the above structural formula (II) may be further bonded to the phenol of formula (I) via a methylene group. Compounds with a structure in which phenol is bonded are also produced. Therefore, the co-condensed phenol used in this invention often contains these as subcomponents. In the epoxy resin composition used in this invention,
There is no problem with the production of these subcomponents as long as there is no extreme increase in the softening temperature, and it is preferable to use a co-condensed phenol resin with a softening temperature within the range of 50 to 140°C.

The above biphenol is a solid with a melting point of 282°C,
The phenol resin co-condensed with the phenol represented by the above general formula (I) has a softening temperature of 50 to 1
40'C solid form, hydroxyl equivalent 90-180
It is preferable to use one having a ratio of g/eq. As described above, since the co-condensed phenolic resin has a biphenyl skeleton that is more rigid than other phenolic curing agents, the resulting cured product has a high glass transition temperature, a low coefficient of linear expansion, and a high water absorption rate. rate is small. In particular, as a phenol represented by the above general formula (1), when R is a hydrocarbon residue having 1 to 4 carbon atoms, such as a methyl group, the water absorption rate is reduced more effectively than when R is a hydrogen atom. be able to.

The above-mentioned special co-condensed phenol resin of component B can be obtained according to a conventional method, for example, by the following two methods. 1st
In this method, biphenol is methylolated using aldehydes such as formalin and paraformaldehyde, and this is reacted with the phenol represented by the above general formula (1) to form a novolac. The second method is obtained by directly converting biphenol and the phenol of general formula (1) into novolak. The above biphenol (X
) and the phenol (Y) represented by the above general formula (1) varies depending on R in the above general formula (1), but the molar ratio is X:Y = 1:1 to 1:20. It is preferable to set it to .

When using a special co-condensed phenol resin as described above as a curing agent for the epoxy resin of component A, the curing agent component may be composed only of the above-mentioned co-condensed phenol, or it may be used in combination with other commonly used phenol resins. You may. Examples of the commonly used phenolic resins include phenol novolac resins, cresol novolak resins, bisphenol A novolak resins, and phenol-modified products of xylene resins. When both are used together in this way, the blending ratio of the co-condensed phenol resin and the commonly used phenol resin is 100 parts by weight (hereinafter abbreviated as "parts") of the former and 100 parts or less of the latter. It is preferable to set it to .

That is, if it is set outside the above range, the resulting cured product will have insufficient resin strength at high temperatures.

The above epoxy resin (component A) and co-condensed phenol resin (
The mixing ratio of component B) with the curing agent is such that the amount of hydroxyl groups in the curing agent is 0.6 to 1.0 per equivalent of epoxy group in component A.
It is preferable to set the amount to 5 equivalents. If it is set outside the above range, the resulting cured product will still have insufficient resin strength at high temperatures.

In addition, a filler is usually used together with the epoxy resin as the A component and the co-condensed phenol resin as the B component. The above fillers include silica, alumina, titanium oxide, iron oxide, calcium silicate, calcium carbonate, barium sulfate,
Inorganic fillers such as molybdenum disulfide, potassium titanate, alumina fibers, whiskers such as silicon carbide and silicon nitride,
Examples include ceramics such as silica titania, cordierite, and eucryptite.

In addition, the epoxy resin composition used in this invention requires other additives such as a coupling agent, a curing accelerator, a wax, a flame retardant, and a low stress agent in addition to the above-mentioned A component, B component, and filler. It is mixed as appropriate depending on the situation.

As the above-mentioned coupling agent, methoxy or ethoxy silanes such as glycidyl ether type, amine type, thiol type, ureaquive, etc. are appropriately used alone or in combination. The method of use thereof is arbitrary, such as triblending or preheating the filler, or premixing the organic component raw material.

The curing accelerators mentioned above 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.

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

Further, as the low stress agent, silicone resin, fine particles of synthetic rubber, etc. are used.

Furthermore, an ion trap agent is used for the purpose of improving reliability.

The epoxy resin composition used in this invention can be produced, for example, as follows.

That is, a co-condensed phenol resin is prepared by reacting biphenol and the phenol represented by the above general formula (1) in advance according to the method described above. Next, the co-condensed phenol resin, the epoxy resin, and fillers and other additives as necessary are suitably blended and premixed, and then kneaded in a heated state using a kneader such as a mixing roll machine to melt and mix.

After cooling this to room temperature, it can be pulverized by known means and, if necessary, compressed into tablets.

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 thus obtained, the glass transition temperature of the sealing resin is lowered by the action of the co-condensed phenol resin of biphenol contained in the epoxy resin composition and the phenol represented by the general formula (1). Although it has high mechanical strength at high temperatures, its coefficient of linear expansion and water absorption are relatively small. Therefore, package cracks do not occur even at high temperatures.

In addition, if the above-mentioned epoxy resin composition does not contain filler or contains a small amount of filler, it can be dissolved in an organic solvent such as acetone, methyl ethyl ketone, dimethyl formamide, or N-methyl-2-pyrrolidone to form a solution. can be used. Such a mode of use is, for example,
It is performed when a fiber base material such as glass cloth is impregnated with an epoxy resin composition to produce a prepreg sheet.
In this case, it is used in the form of a solution as described above.

[Effects of the Invention] As described above, the semiconductor device of the present invention uses a special epoxy resin composition containing a special co-condensed phenol resin obtained using the above biphenol and a specific phenol. It is constructed by sealing a semiconductor element. Therefore, package cracks do not occur even under severe conditions such as solder mounting. Further, the above-mentioned special epoxy resin composition is used not only as a sealing resin for semiconductor elements, but also when, for example, the above-mentioned epoxy resin composition is used as an impregnating resin to produce a prepreg sheet. This prepreg sheet is used when manufacturing a printed wiring board by laminating this prepreg sheet and copper foil, and the resulting board is suitably used as a surface mounting board.

Next, examples will be described together with comparative examples.

First, prior to Examples, co-condensed phenol resins A and B were prepared according to the following method.

(Co-condensed phenolic resin A) 186 g of biphenol was reacted with formalin in an alkaline atmosphere to form a resol by a conventional method, and then 940 g of phenol was added thereto to form a novolak in an acidic atmosphere. Then, excess phenol was removed under reduced pressure to produce a co-condensed phenol resin A having a hydroxyl equivalent of 100 g/eq and a softening temperature of 100 to 185°C.

(Co-condensed phenol resin B) 186 g of biphenol and 1080 g of cresol were used. Other than that, a co-condensed phenol resin B having a hydroxyl equivalent of 110 g/eq and a softening temperature of 115° C. was prepared by performing the same operation as the above-mentioned co-condensing phenol A.

[Examples 1 to 4] The above co-condensed phenolic resins A and B and the raw materials shown in Table 1 below were blended in the proportions shown in the same table, and 2
The mixture was mixed for a minute and kneaded using an extruder. Then, the kneaded material was pulverized to obtain the desired powdered epoxy resin composition.

(Left below) Next, the epoxy resin compositions obtained in Examples 1 to 4 were transfer-molded to produce bending test pieces and water absorption test pieces having shapes defined by JIS. Using this test piece, bending strength at 220°C, TMA (Thermal
+al mechanical analysis), the coefficient of linear expansion and glass transition temperature,
Then, the saturated water absorption rate under 85°C/85%RH was measured and evaluated. The results are shown in Table 2 below.

Further, a semiconductor device was manufactured by molding a semiconductor element by transfer molding using the above epoxy resin composition. This semiconductor device is an 80-pin four-way flat package (QFP) (20mo + x 14s x thickness 2
．． 5 m), 7 cabinets x 7 bowels of Guibon pad,
6.5111X6. It has a chip size of FBll. The semiconductor device thus obtained was subjected to vapor phase soldering (V
PS) until package cracks occur.
The critical moisture absorption time was measured at °C x 85% RH. The results are also shown in Table 2 below.

(Margins below) From the results in Table 2, the products according to the implementation have high bending strength and low coefficient of linear expansion. Furthermore, it has a high glass transition temperature and a long critical moisture absorption time. From this, the specific product has low stress properties,
It can be seen that it has excellent heat resistance reliability and moisture resistance reliability.

Claims (2)

[Claims] (1) A semiconductor device in which a semiconductor element is sealed using an epoxy resin composition containing a co-condensed phenol resin of biphenol and phenol represented by the following general formula (I) and an epoxy resin. ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) [In the above formula (I), R is a hydrogen atom or a hydrocarbon residue having 1 to 4 carbon atoms. ] (2) An epoxy resin composition for semiconductor encapsulation containing a co-condensed phenol resin of biphenol and phenol represented by the following general formula (I), and an epoxy resin. ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) [In the above formula (I), R is a hydrogen atom or a hydrocarbon residue having 1 to 4 carbon atoms. ]