JP2922672B2 - Semiconductor device manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to relates to preparation of good semiconductor <br/> equipment reliability.

[0002]

2. Description of the Related Art Semiconductor devices such as transistors, ICs, and LSIs are sealed with plastic packages or the like to form semiconductor devices from the viewpoint of protection from the external environment and the viewpoint of enabling handling of the devices. 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 pins into a mounting board.

In recent years, the integration and speed of semiconductor devices such as LSI chips have been increasing, and the density of mounting has been increasing due to the demand for smaller and more sophisticated electronic devices.
From such a viewpoint, a surface mount type package is becoming mainstream instead of a pin insertion type package such as DIP. In a semiconductor device using a package of this type, pins are taken out in a plane, and the pins are fixed directly to the surface of a mounting board by soldering or the like. Such a surface-mount type semiconductor device can take out pins in a planar manner as described above, and has the advantages of being thin, light, and small. Therefore, in addition to the advantage that the occupied area on the mounting board is small,
It also has the advantage that double-sided mounting on a substrate is also possible.

[0004]

However, in a semiconductor device using a package for surface mounting as described above, if the package itself has absorbed moisture before surface mounting, the package is subjected to the vapor pressure of water during solder mounting. There is a problem that cracks occur in the package. That is, in the surface-mount type semiconductor device as shown in FIG. 1, moisture penetrates into the package 3 through the sealing resin 1 as shown by the arrow A, and mainly the surface of the Si chip 7 and the die bond pad 4. Stagnate on the back. And, when performing solder surface mounting such as vapor phase soldering, the accumulated water is vaporized by heating in the solder mounting, and due to its vapor pressure,
As shown in FIG. 2, the resin portion on the back surface of the die bond pad 4 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 2 denotes a lead frame, and reference numeral 8 denotes a bonding wire.

As a solution to such a problem, a method of sealing a semiconductor element with a package and then sealing the whole obtained semiconductor device and opening the semiconductor device immediately before surface mounting, or the method described above immediately before surface mounting. Semiconductor device at 100 ° C
A method of drying for 4 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 longer and more labor is required.

SUMMARY OF THE INVENTION The present invention has been made in view of the above 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 has a low stress property capable of withstanding heating during solder mounting. It is an object of the present invention to provide a method for manufacturing a semiconductor device which can be manufactured well .

[0007]

To achieve the above object, according to an aspect of the present invention, shall apply in the method of manufacturing a semiconductor device sealed with resin by transfection fir molding a semiconductor device using the d epoxy resin composition, An epoxy resin composition containing the following components (A) to (C) as the epoxy resin composition, wherein the content of the following component (C) is set to 70 to 85% by weight of the entire epoxy resin composition. used, and when the resin sealing by the epoxy resin composition, a production method of a semiconductor device is omitted post-cure process and Abstract. (A) A crystalline epoxy resin represented by the following general formula (1).

Embedded image (B) A phenol aralkyl resin represented by the following general formula (2).

Embedded image (C) an inorganic filler.

[0008]

The semiconductor package resin-sealed by the transfer molding using a thermosetting resin composition containing an epoxy resin as a main component is solder-immersed on a printed circuit board (PCB) and surface-mounted. As a method of preventing the package cracks generated at the time, the moisture absorption to the sealing resin is suppressed, the adhesive strength between the back surface of the die bond pad and the surface of the semiconductor element and the sealing resin is increased, and the sealing resin itself is used. There are three possible ways to increase the strength of the paper. The present inventors have paid attention to the method of suppressing moisture absorption for the sealing resin, and as a result of repeated research centered on this method, when using an epoxy resin composition for transfer molding having a hydrophobic epoxy resin skeleton. It has also been found that the absorption of moisture into the sealing resin is suppressed, and the solder package crack resistance is greatly improved. As a result of repeating a series of studies on the best molding conditions and the best curing conditions for the transfer molding sealing resin composition comprising this hydrophobic epoxy resin skeleton because of its low hygroscopicity, the present invention was achieved. When such a special epoxy resin composition is used, resin sealing can be performed without passing through a post-curing (after-curing) step. By not passing through the post-curing step, the water absorption of the sealing resin is low. As a result, the present inventor has found that the reliability of the semiconductor device is not reduced.

Next, the present invention will be described in detail.

The epoxy resin composition used in the present invention is obtained by using a special epoxy resin (component A), a phenol aralkyl resin (component B), and an inorganic filler (component C). It is usually in the form of a powder or a tablet obtained by compressing it.

The special epoxy resin (component A) is a biphenyl type epoxy resin, and is a crystalline epoxy resin represented by the following general formula (1).

[0012]

Embedded image

As described above, by adding a lower alkyl group to the phenyl ring having a glycidyl group, the phenyl ring has water repellency. The epoxy resin component may be composed only of the crystalline epoxy resin represented by the general formula (1), or may be combined with any other commonly used epoxy resin as long as the solder package cracking property is not deteriorated. You may use together. In the latter case, a part of the epoxy resin component is composed of the crystalline epoxy resin represented by the general formula (1). Examples of the commonly used epoxy resin include various epoxy resins such as a cresol novolak type epoxy resin, a phenol novolak type epoxy resin, a novolak bis A type and a bisphenol A type epoxy resin. When both are used in this manner, the epoxy resin (A component) represented by the general formula (1) is 50% by weight of the entire epoxy resin component (hereinafter abbreviated as “%”).
It is preferable to set the above value, particularly preferably 80% or more.

The above phenol aralkyl resin (component B)
Is represented by the following general formula (2).

[0015]

Embedded image

The phenol aralkyl resin represented by the general formula (2) serves as a curing agent for the special epoxy resin (component (A)), and causes aralkyl ether and phenol to react with a Friedel-Crafts catalyst. It can be obtained by: Generally, α, α'-dimethoxy-
A condensation polymerization compound of p-xylene and a phenol monomer is known. And as said phenol aralkyl resin, softening point 50-110 degreeC, hydroxyl equivalent 150-
Preferably, one having 220 is used.

The mixing ratio of the special epoxy resin (component A) and the phenol aralkyl resin (component B) is a stoichiometric equivalent ratio, based on 1 equivalent of epoxy group in the special epoxy resin (component A). It is preferable to mix the phenol aralkyl resin (component B) so that the hydroxyl group in the phenol aralkyl resin is 0.9 to 1.3.

As the inorganic filler (component C) used together with the above-mentioned special epoxy resin (component A) and phenol aralkyl resin (component B), crystalline and fusible silica is used. ~ 20μ
It is preferable to use amorphous crushed fused silica having a maximum particle diameter of less than 100 μm. The content of the inorganic filler (component C) is 70% of the entire epoxy resin composition.
It is necessary to set in the range of ~ 85%. That is, when the content of the inorganic filler is less than 70%, the moisture absorption of the cured product of the encapsulating resin composition generally increases, and when it exceeds 85%, the melt viscosity during transfer molding generally increases, and the void of the molded product increases. This is because the quality of the molded product is deteriorated due to the remaining of steel, defective filling of the cavity, an increase in the wire flow and the stage shift, and the like.

The epoxy resin composition used in the present invention contains, if necessary, other additives conventionally used in addition to the above-mentioned components A to C.

Other additives include a curing accelerator, a flame retardant, a flame retardant aid, an internal mold release agent, a colorant, an adhesion aid, a stress reducing agent, and various ion trapping agents such as hydrotalcite. Is raised.

Examples of the curing accelerator include curing accelerators such as amine-based, amine-based-boron-based mixtures, phosphorus-based, and phosphorus-based-boron-based mixtures, and are used alone or in combination.

As the flame retardant and the flame retardant auxiliary, a compound such as a novolak-type brominated epoxy resin, a bis-A-type brominated epoxy resin, antimony trioxide or antimony pentoxide, etc. are used alone or in combination. Used.

Examples of the internal mold release agent include known wax compounds such as higher fatty acids, higher fatty acid esters, higher fatty acid calcium, higher fatty acid amides, polyethylene and the like, and these are used alone or in combination.

Examples of the colorant include various carbon blacks, titanium oxide, and other various known pigments and dyes, if necessary. These may be used alone or in combination.

Examples of the above-mentioned adhesion aid include various conventionally known silane coupling agents and various titanium coupling agents. As the silane coupling agent,
Glycidyl ether type, amine type, thiocyan type, urea type and other methoxy or ethoxy silanes are used, and they are used alone or in combination.
In some cases, for example, the above-mentioned adhesion aid is used in a reaction vessel equipped with a stirrer at 120 to 180 ° C., particularly preferably 130 ° C. using the phenol aralkyl resin (component B).
It can be used to raise the temperature to ~ 150 ° C to react.

The epoxy resin composition used in the present invention can be produced by using the above-mentioned components, for example, as follows. That is, after the above components are appropriately mixed and preliminarily mixed, the mixture is kneaded in a kneading machine such as a mixing roll machine in a heated state and melted and mixed. After cooling to room temperature, it can be manufactured by a series of steps of pulverizing by a known means and tableting as required.

The sealing of a semiconductor device using such an epoxy resin composition is performed, for example, by molding a lead frame on which a semiconductor device electrically connected by a gold wire or the like is mounted using a molding die. Can be molded. As such transfer molding,
In general, there are various types of transfer molding methods, such as a resin molding method for a large number of cavities at the same time, and a multi-plunger system for performing a transfer molding with a small pot diameter from one pot and one cavity to one pot several cavities. In the transfer molding, the molding is performed in a temperature range of 150 to 200 ° C. with a molding time of several tens seconds to several hundred seconds. In this molding process, the epoxy resin composition is heated, transferred in a molten state into the cavity by a plunger of a molding machine, and the molding is completed in a gelled and cured shape. Plastic sealing is completed.

Then, after the above steps, usually 150 to 2
Tens of minutes to several hours at a temperature of 00 ° C., specifically 175
In general, the crosslinking reaction of the sealing resin is promoted in a post-curing (after-curing) step at 3 ° C. for 3 to 20 hours. However, the epoxy resin composition of the present invention can be cured without performing the above-mentioned post-curing step, and the effect of suppressing moisture absorption in the package is more exerted without passing through the post-curing step. That is, in the manufacturing process of the semiconductor device of the present invention, for example, the gelation time of the epoxy resin composition at the transfer molding temperature is preferably 10 to 40.
By setting the time to seconds, particularly preferably 10 to 25 seconds,
There is no problem at the time of release from the molding die, and the package is excellent in low hygroscopicity as compared with the case where the package has passed through a post-curing step. That is, by performing resin sealing as described above, during the solder mounting process,
The occurrence of package cracks is suppressed, and a highly reliable semiconductor device having excellent solder heat resistance can be obtained.

[0029]

As described above, it is possible to obtain by the production method of the present invention.
That the semiconductor device, the special epoxy resin (A component)
And a special epoxy resin composition containing a phenol aralkyl resin (component (B)) and an inorganic filler (component (C)) mixed in a specific range. Due to the interaction of each component, moisture absorption of the sealing resin is suppressed, and even under severe conditions such as solder mounting, package crack does not occur,
Has excellent moisture resistance reliability. In addition, the method of the present invention manufactures the above-described semiconductor device having high moisture resistance reliability by omitting the post-curing step of the encapsulating resin. Since the step is omitted, high efficiency of the sealing work can be realized.

Next, examples will be described together with comparative examples.

First, the following compounds were prepared for preparing the epoxy resin composition.

<< Epoxy Resin A >> 4,4′-bis (2,3-epoxypropoxy) -3,
3 ', 5,5'-tetramethylbiphenyl: epoxy equivalent 195 << Epoxy resin B >> o-cresol novolak type epoxy resin: epoxy equivalent 195

<< Curing Agent A >> The repeating number n = 1 to 100 represented by the general formula (2)
Phenol aralkyl resin: softening point 76 ° C., hydroxyl equivalent 175 << inorganic filler >> crushed fused silica: average particle diameter 7 μm, maximum particle diameter 90 μ
m << Curing accelerator A >> Trifenylphosphine << Curing accelerator B >> 1,8-diazabicyclo (4,3,0) nonene-5 << Flame retardant A >> Novolak-type brominated epoxy resin: Epoxy equivalent 27
5 << Flame retardant B >> Antimony trioxide << Colorant >> Carbon black << Internal release agent >> Higher fatty acid ester wax << Adhesive aid >> 3-glycidoxypropyltrimethoxysilane

[0034]

Examples 1 to 5 The components shown in Table 1 below were blended in the proportions shown in the same table, and mixed with a mixing roll machine.
The mixture was kneaded at 5 ° C. for 5 minutes to prepare a sheet-shaped resin composition. Then, the sheet-shaped resin composition was pulverized to obtain a desired epoxy resin composition for transfer molding.

[0035]

[Table 1]

[0036]

Comparative Examples 1 to 5 The epoxy resin compositions for transfer molding obtained in the above Examples were prepared as Comparative Examples in order to measure the properties of the cured product and the properties of the semiconductor device when the post-curing step was performed.

[0037]

Comparative Examples 6 to 9 The components shown in Table 2 below were used and blended in the proportions shown in the same table. Otherwise in the same manner as in Example 1, the desired epoxy resin composition for transfer molding was obtained.

[0038]

[Table 2]

The 175 ° C. The gel time of Example Contact and trans fir molding epoxy resin composition obtained in Comparative Example (heating plate method), the cured product properties (glass transition temperature, coefficient of linear expansion, 25 ° C. and 260 Flexural modulus at ℃, bending strength, water absorption at 85 ° C / 85% RH × 168hr)
Was measured. The ratio cured product of the Comparative Examples are KoTsuta a curing step after 5 hours in a constant temperature bath at 175 ° C..

Further, using the epoxy resin composition for transfer molding, a semiconductor device is molded by a known transfer molding method using a molding die heated to 175 ± 5 ° C. (molding time: 120 seconds). ) To obtain a semiconductor device. This semiconductor device is an 80-pin four-way flat package (QFP: 20 mm × 14 mm × 2.0 mm thick)
A 7.5 mm × 7.5 mm semiconductor element is bonded on a die bond plate having a size of 8 mm × 8 mm using a thermosetting epoxy silver paste, and is electrically connected to the inner lead of a 42 alloy lead frame and a 20 μm gold wire. It is connected. Further, the ratio Comparative Examples products, KoTsuta a curing step after 5 hours in a constant temperature bath at 175 ° C.. After leaving the semiconductor device thus manufactured in a constant temperature and humidity bath at 85 ° C. and 85% RH for 96 hours, it was immersed in a solder bath at 260 ° C. for 10 seconds.
The occurrence of package cracks was observed. The results are shown in Tables 3, 4 and 5 below.

[0041]

[Table 3]

[0042]

[Table 4]

[0043]

[Table 5]

*: In Comparative Example 8 , the melt viscosity was extremely high, and a test piece used for transfer molding could not be produced.

From the results of Tables 3, 4 and 5, the cured products of Comparative Examples 6 to 9 have low strength and high water absorption. Also,
Many cracks are generated in solder crack test. And
The cured products of Comparative Examples 1 to 5 are slightly better in characteristics than Comparative Examples 6 to 9 . Also, the number of cracks generated in the solder crack test is better than those of Comparative Examples 6 to 9 . But the real
When compared with the examples, Comparative Examples 1 to 5 are all characteristics.
Inferior. On the other hand, the cured product of the example has a high strength and a lower water absorption than the comparative example. Moreover, the number of cracks generated in the solder crack test is small.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view illustrating a state of occurrence of a package crack in a conventional semiconductor device.

FIG. 2 is a vertical cross-sectional view illustrating a state of occurrence of a package crack in a conventional semiconductor device.

Continuation of the front page (56) References JP-A-4-325517 (JP, A) JP-A-63-186724 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 23 / 28 H01L 23/30 H01L 21/56

Claims (2)

(57) [Claims] 1. A method of manufacturing a semiconductor device by sealing a semiconductor element with a resin by transfer molding using an epoxy resin composition, wherein the epoxy resin composition comprises the following components (A) to (C): A post-curing step is carried out using an epoxy resin composition containing the following component (C) in a content of 70 to 85% by weight of the entire epoxy resin composition and sealing the resin with the epoxy resin composition. A method for manufacturing a semiconductor device, which is omitted. (A) A crystalline epoxy resin represented by the following general formula (1). Embedded image (B) A phenol aralkyl resin represented by the following general formula (2). Embedded image (C) an inorganic filler. Wherein the epoxy resin composition, production method of a semiconductor device according to claim 1, wherein the gelling time in transfected fir molding temperature is 10 to 40 seconds.