JP2002194064A - Resin composition for encapsulating semiconductor and semiconductor device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin composition for encapsulating a semiconductor, excellent in low stress property and adhesion property to an Ni-plated flame and capable of improving a reliability as a device, in encapsulating usage required for a high thermal-conductivity such as a power device, and to provide a semiconductor device. SOLUTION: The resin composition for sealing of the semiconductor is composed of, as essential components, (A) a modified epoxy resin, (B) a silane- modified novolac phenol resin, and (C) a crystalline silica. This modified epoxy resin is obtained by reaction of a mixture, wherein a novolac-type resin is mixed in either one epoxy resin of a biphenyl-type epoxy resin and an epoxy resin having a dicycropentadiene structure, with a dimethyl polysiloxane having an amino-modified group at both terminals. As the silane-modified novolac phenol resin, a reaction product of γ-glysidoxypropyl trimethoxysilane with an amino-type catalyst, is preferably used. The semiconductor device is produced by sealing a semiconductor element using the above resin composition for sealing the semiconductor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin-based encapsulation resin composition, which is used for encapsulation applications requiring high thermal conductivity such as power devices, and which has a low stress and a nickel plating frame. The present invention relates to a resin composition for semiconductor encapsulation which has excellent adhesiveness and can improve the reliability as a device, and a semiconductor device in which a semiconductor element is encapsulated using the same.

[0002]

2. Description of the Related Art Conventionally, transistors, ICs, and LSIs have been used.
Such semiconductor elements are usually sealed with a ceramic package, a plastic package, or the like, and are regarded as a semiconductor device. The former ceramic package itself has heat resistance and excellent moisture resistance, so it is resistant to high temperature and high humidity, has excellent mechanical strength, and is highly reliable. is there.

However, there is a problem that the constituent materials are relatively expensive and the mass productivity is inferior. Therefore, in recent years, resin sealing using the latter plastic package has become mainstream. An epoxy resin composition has conventionally been used for resin encapsulation using a plastic package by utilizing the property of being excellent in heat resistance, and has achieved good results.

[0004] Such an epoxy resin composition for encapsulating a semiconductor element generally includes an epoxy resin as a main material, a phenol resin as a curing agent, an amine compound as a curing accelerator, and other optional compounds. Components comprising a rubber component as an elasticity-imparting agent and silica powder as an inorganic filler have been used as those excellent in sealing workability particularly during transfer molding.

On the other hand, in large home appliances and industrial equipment,
Semiconductors that control large power include power devices such as transistors, diodes, and thyristors. Since such a power device is exposed to a high voltage, the heat generated by the semiconductor element is extremely large, and if the heat dissipation is poor, the package and the semiconductor element are likely to be destroyed.

The sealing resin used for the power device is
High thermal conductivity is required, but when sealed with a conventional sealing resin, sealing with crystalline silica powder, which is used as an inorganic filler, is high due to the high thermal conductivity. There is a problem that the thermal expansion coefficient of the whole resin becomes too large, and the internal stress of the resin in the semiconductor device after sealing becomes large.

A nickel-plated frame is used as a frame for a power device. However, a nickel-plated frame generally has lower adhesiveness with a sealing resin than a copper frame or a 42-alloy frame. Easily separates from the sealing resin in the inside. When such peeling occurs, there is a problem that the thermal conductivity in the sealing resin is reduced and the reliability of the device is also reduced.

On the other hand, as a method for reducing the internal stress in the sealing resin, it is conceivable to add silicone oil or a rubber component to the sealing resin composition. There is a risk of seepage at the resin interface, and the adhesive strength at the interface tends to decrease as described above.

[0009]

SUMMARY OF THE INVENTION The present inventors have solved the above problems and provided an epoxy resin composition for semiconductor encapsulation which can be used for applications requiring high thermal conductivity such as power devices. As a result of intensive studies for the purpose, a resin composition using a specific modified epoxy resin as the main material and a specific modified novolak phenol resin as a curing agent is an excellent resin composition for power device applications Has been found, and the present invention has been completed.

[0010]

That is, the present invention provides a resin composition for encapsulating a semiconductor containing the following components. (A) Modification by reacting a mixture of one of a biphenyl type epoxy resin and an epoxy resin having a dicyclopentadiene skeleton and a novolak type epoxy resin with dimethylpolysiloxane having an amino-modified group at both ends. Epoxy resin. (B) Silane-modified novolak phenolic resin (C) Crystalline silica

In particular, the resin composition for semiconductor encapsulation of the present invention can provide high thermal conductivity required for power devices by using crystalline silica powder having high thermal conductivity as a filler. It is.

The present invention also provides a semiconductor device in which a semiconductor element is sealed using the above resin composition for semiconductor sealing.

[0013]

Embodiments of the present invention will be described below in detail.

The modified epoxy resin as the component (A) used in the resin composition for semiconductor encapsulation of the present invention is a main component of the composition, and is a mixture of a biphenyl type epoxy resin and a cresol novolac type epoxy resin. Or a mixture of an epoxy resin having a dicyclopentadiene skeleton and a novolak-type epoxy resin, which is siloxane-modified with a specific dimethylpolysiloxane.

That is, in the present invention, by reducing the specific epoxy resin with siloxane, it is possible to reduce the stress (stress relaxation) inside the sealing resin. Also,
In the present invention, dimethylpolysiloxane having an amino-modified group at both terminals is used as the siloxane modifier, and is reacted with the above-mentioned epoxy resin mixture to form siloxane crosslinks.

The biphenyl type epoxy resin used in the present invention has a structure represented by the following general formula.

[0017]

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Of the biphenyl type epoxy resins represented by the above general formula, 3,3 ', 5,5
It is preferable to use 5'-tetramethylbiphenyl diglycidyl ether.

The biphenyl type epoxy resin is
Epoxy equivalent is 149 to 230, preferably 149 to 2
It is desirable to use those in the range of 10. In particular, 23
If an epoxy resin having an epoxy equivalent exceeding 0 is used, the heat resistance of the cured product tends to decrease. Therefore, it is preferable to use an epoxy resin having an epoxy equivalent within the above range.

Further, the biphenyl type epoxy resin has a softening point or a melting point of 5 from the viewpoint of workability and kneading properties.
It is desirable to use one in the range of 0 to 130 ° C, preferably 60 to 120 ° C. Softening point or melting point 50
If the temperature is lower than ℃, the workability tends to deteriorate,
If it exceeds 130 ° C., the kneadability tends to deteriorate.

On the other hand, as the epoxy resin having the dicyclopentadiene skeleton, one represented by the following general formula is used.

[0022]

Embedded image

It is preferred that R in the above formula be a hydrogen atom or a methyl group from the viewpoint of fluidity and curability.

The epoxy resin having a dicyclopentadiene skeleton preferably has an epoxy equivalent of 270 to 300, preferably 280 to 300, from the viewpoint of adhesion and curability. Epoxy equivalent is 2
If it is less than 70, the adhesiveness tends to decrease,
On the other hand, when the epoxy equivalent exceeds 300, the curability at the time of molding tends to decrease.

Further, the epoxy resin having a dicyclopentadiene skeleton has the following characteristics in view of handleability and adhesion.
It is desirable to use one having a softening point of 75 to 90 ° C, preferably 80 to 90 ° C. If the softening point is lower than 75 ° C., the resin composition may cause a blocking phenomenon. If the softening point is higher than 90 ° C., the adhesiveness tends to decrease.

The epoxy resin used in the present invention is a mixture of the above biphenyl type epoxy resin or the epoxy resin having a dicyclopentadiene skeleton and a novolak type epoxy resin. In the present invention, by mixing the novolak type epoxy resin, the sealing resin obtained from the resin composition for semiconductor encapsulation of the present invention can be provided with the property of improving the adhesion to the nickel plating frame. .

As the novolak type epoxy resin capable of imparting such properties, cresol novolak type epoxy resin, phenol novolak type epoxy resin and the like can be mentioned. Among these, cresol novolak type epoxy resin is preferable from the viewpoint of moldability. It is preferable to use

The cresol novolak type epoxy resin has an epoxy equivalent of 185 to 20 from the viewpoint of moldability.
5, preferably in the range of 192 to 199. When the epoxy equivalent is less than 185, the fluidity tends to decrease, while when the epoxy equivalent exceeds 205, the curability tends to be poor, which is not preferable.

Further, it is desirable to use the cresol novolak type epoxy resin having a softening point in the range of 60 to 80 ° C., preferably 65 to 75 ° C., from the viewpoint of handleability and moldability of the resin. When the softening point is lower than 60 ° C., the resin composition tends to cause a blocking phenomenon, and when the softening point is higher than 80 ° C., the fluidity tends to decrease.

In the resin composition for semiconductor encapsulation of the present invention, the silane-modified novolak phenol resin as the component (B) acts as a curing agent for the modified epoxy resin as the component (A), and particularly, γ -By using a modified novolak phenol resin obtained by reacting glycidoxypropyltrimethoxysilane with an amino-based catalyst as a curing agent, the curability and adhesion of the sealing resin that seals the semiconductor element are improved. It is preferred.

Further, as the filler used as the component (C) in the present invention, it is preferable to use crystalline silica, more preferably, a powder having an average particle diameter of 10 to 30 μm. By using crystalline silica in the present invention, it is possible to impart high thermal conductivity to the obtained sealing resin, and it is suitable for a sealing resin that requires high thermal conductivity such as a power device. Excellent characteristics can be imparted as compared with amorphous silica or the like.

The powdery crystalline silica has an average particle size of 0.01 to 60 in terms of uniform filling property and fluidity.
It is preferable to use one having a range of μm, more preferably one having a range of 0.1 to 15 μm.

The resin composition for semiconductor encapsulation of the present invention contains the above components (A) to (C) as essential components, and the content of each component is as follows:
30 to 60 parts by weight of the component (B), 500 to 500 parts by weight of the component (C)
900 parts by weight, preferably 40 to 55 parts by weight of the component (B) and 600 to 850 parts by weight of the component (C).
By setting the content in such a range, the obtained semiconductor encapsulating resin has good high thermal conductivity, excellent adhesion to the nickel plating frame, and good molding workability.

In particular, if the content of the crystalline silica as the component (C) is too small, the viscosity of the composition at room temperature becomes too low to cause precipitation of the inorganic filler during storage, and
There is a tendency that the moisture absorption rate increases and the humidity resistance reliability deteriorates. Furthermore, the resulting sealing resin cannot be provided with high thermal conductivity, and tends to be unsuitable for use in power devices. On the other hand, if the content ratio of the crystalline silica is too large, the fluidity when the composition is heated decreases,
There is a tendency that the discharge property and the coating workability during transfer molding tend to be poor.

The resin composition for encapsulating a semiconductor of the present invention contains the above-mentioned components (A) to (C) as essential components. Various additives such as a curing accelerator (curing catalyst), an inorganic filler, a flame retardant, a wax, a pigment, a dye, a silane coupling agent and a titanate coupling agent can be appropriately compounded.

Examples of the curing accelerator (curing catalyst) include amine, imidazole, phosphorus, boron and phosphorus-boron curing accelerators. Specifically, alkyl-substituted guanidines such as ethylguanidine, trimethylguanidine, phenylguanidine and diphenylguanidine, 3- (3,4-dichlorophenyl)-
3-substituted phenyl-1,1-dimethylureas such as 1,1-dimethylurea, 3-phenyl-1,1-dimethylurea, 3- (4-chlorophenyl) -1,1-dimethylurea, 2-methyl Imidazolines such as imidazoline, 2-phenylimidazoline, 2-undecylimidazoline and 2-heptadecylimidazoline; monoaminopyridines such as 2-aminopyridine; N, N-dimethyl-N-
(2-hydroxy-3-allyloxypropyl) amine-
Amine imides such as N'-lactide, ethylphosphine, propylphosphine, butylphosphine, phenylphosphine, trimethylphosphine, triethylphosphine, tributylphosphine, trioctylphosphine, triphenylphosphine, tricyclohexylphosphine, triphenylphosphine / triphenylborane Complexes, organophosphorus compounds such as tetraphenylphosphonium tetraphenylborate, diazabicycloalkenes such as 1,8-diazabicyclo [5,4,0] undecene-7 and 1,4-diazabicyclo [2,2,2] octane And the like. These can be used alone or in combination of two or more.

The inorganic filler is not particularly limited, and various inorganic fillers can be used as long as the thermal conductivity is not impaired. Specifically, fused silica,
Examples include clay, gypsum, calcium carbonate, barium sulfate, alumina oxide, beryllium oxide, silicon carbide, silicon nitride, aerosil, and the like.

Examples of the flame retardant include novolak type brominated epoxy resin, brominated bisphenol A type epoxy resin, metal compounds such as antimony trioxide, antimony pentoxide, magnesium hydroxide and aluminum hydroxide, red phosphorus, phosphate ester And the like, and these can be used alone or in combination of two or more.

Examples of the wax include higher fatty acids, higher fatty acid esters, higher fatty acid calcium, and compounds such as amides. These compounds may be used alone or in combination of two or more.

Examples of the silane coupling agent include γ-mercaptopropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β-
(3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, amino group-containing silane, and the like are used, and these are used alone or in combination of two or more.

Further, the resin composition for semiconductor encapsulation of the present invention may further contain, if necessary, components such as silicone oil, silicone rubber, synthetic rubber, and reactive diluent in addition to the above-mentioned other additives. An ion scavenger such as hydrotalcites or bismuth hydroxide may be appropriately compounded for the purpose of further reducing the stress or improving the reliability in the moisture resistance reliability test.

The resin composition for semiconductor encapsulation of the present invention can be produced, for example, as follows. That is,
After mixing the components (A) to (C) and other additives as necessary, the mixture is kneaded in a kneader such as a kneader in a heated state and melt-mixed to obtain a composition. Next, after cooling this at room temperature (about 25 ° C.), it is crushed, and this is compressed into a tablet by a tableting machine. Needless to say, the composition in a molten state can be directly formed into a tablet by omitting the crushing step.

The production of a semiconductor device using the resin composition for semiconductor encapsulation of the present invention can be carried out by various methods known per se. For example, a resin tablet for semiconductor encapsulation obtained by tableting as described above is heated to a predetermined temperature, and this is heat-molded at a predetermined temperature for a predetermined time using a transfer molding machine and cured to form a semiconductor element. The semiconductor device of the present invention can be manufactured by resin sealing.

[0044]

Next, the present invention will be described in more detail with reference to examples, but it goes without saying that various modifications and applications are possible without departing from the gist of the present invention.

Examples 1 to 3 and Comparative Examples 1 to 3 Raw materials were blended and mixed according to the formulation shown in Table 1 below, melt-kneaded using a kneader, and the kneaded product was cooled, crushed, and pressed. Tableting was performed with a tablet machine to produce a resin tablet for semiconductor encapsulation. The following ingredients were used in Table 1.

Modified epoxy resin: 20 parts by weight of biphenyl epoxy resin (epoxy equivalent: 194, softening point: 108 ° C.) and 80 parts by weight of cresol novolac type epoxy resin (epoxy equivalent: 195, softening point: 70 ° C.) are heated to 150 ° C. After melting, 20 parts by weight of a linear polydimethylsiloxane having amino-modified groups at both ends (weight average molecular weight 9000, specific gravity 0.96) is added, and a crosslinking reaction is carried out for about 5 hours. It was obtained by grinding.

Epoxy resin: Cresol novolak type epoxy resin (epoxy equivalent: 200, softening point: 70 ° C.)

Modified phenolic resin: novolak type phenolic resin (hydroxyl equivalent 105, softening point 80 ° C.) 100
Parts by weight were heated and melted at 170 ° C., and an amino-based catalyst (1,8-diazabicyclo [5,4,0] undecene-
7) 2 parts by weight were mixed, and 2 parts by weight of γ-glycidoxypropyltrimethoxysilane were further added. The mixture was allowed to react sufficiently until no bubbles of methanol were generated, and then cooled to obtain. .

Phenol resin: Novolak type phenol resin (hydroxyl equivalent: 105, softening point: 80 ° C.)

Curing catalyst: 1,8-diazabicyclo [5,4,0] undecene-7

Crystalline silica powder: average particle diameter 20 μm

Fused silica powder: average particle size 23 μm

Epoxy bromide resin: Novolac type epoxy bromide resin (epoxy equivalent: 285, softening point: 84 ° C.)

Coupling agent: γ-glycidoxypropyltrimethoxysilane

[0055]

[Table 1]

The following tests were carried out using the resin tablets for semiconductor encapsulation produced as described above, and the results are shown in Table 2.

<Thermal Conductivity> The resin tablets for semiconductor encapsulation prepared in each of the examples and comparative examples were preheated at 80 ° C. by a preheater, and further molded at 175 ° C. for 2 minutes using a transfer press. Into a test piece for measuring heat conductivity, and the heat conductivity (W / m · K) was measured. Thermal conductivity meter is KEMTHERMMO manufactured by Kyoto Electronics Industry Co., Ltd.
QTM-D3.

<Frame Adhesive Strength> In order to conduct an adhesive strength evaluation test on a nickel-plated copper frame, molding was performed under the same conditions as in the thermal conductivity measurement test, and post-curing was performed at 175 ° C. for 5 hours. Was. Using the autograph, the semiconductor device (package) thus obtained is obtained.
The shear adhesive strength (MPa) between the resin and the frame was measured.

<Exfoliation Rate> A semiconductor device (package) obtained in the same manner as in the above-described frame adhesion test except that a nickel-plated frame for a TO-220 package was used was measured using an ultrasonic probe. Then, the peeling inside the package was observed, and the peeling occurrence rate (%) was measured from the peeled package and the number of observations.

<Coefficient of Thermal Expansion> A thermomechanical property test of the resin molded product was performed according to JIS K7197, and the coefficient of thermal expansion was determined.

<Bending elastic modulus>
The bending elastic modulus was determined according to ISK7171.

<Stress Index> The product of the above thermal expansion coefficient and the flexural modulus was defined as the stress index.

<Cooling and Heat Cycle Test> A 16-pin dual in-line package (16p-DIP) was assembled using a test element (3 mm × 6 mm) provided with aluminum wiring, and this was obtained in each of the examples and comparative examples. A test package was prepared by resin sealing and molding with the resin composition. This test package was subjected to a thermal cycle test 100 times for 30 minutes each at -50 ° C. and 150 ° C. in a thermal cycle test apparatus. After the test, the package was disassembled, and the stress property of the resin was evaluated from the deformation amount of the aluminum wiring on the surface of the test element. The evaluation criteria were "poor" when the amount of deformation of the aluminum wiring was 10 μm or more, and "good" when it was less.

[0064]

[Table 2]

As is clear from the results in Table 2 above, the products of the present invention use a specific modified epoxy resin and a modified novolak phenol resin, and therefore have high adhesion to the nickel plating frame. And the rate of occurrence of delamination is completely absent. In particular, since the modified epoxy resin subjected to the specific siloxane modification is used in the example products, it has low stress properties, and shows good results even in the thermal cycle test. In addition, when the crystalline silica powder is used as the filler, it is apparent that the thermal conductivity is excellent, so that the high thermal conductivity required for the power device can be provided.

Examples 4 to 6 and Comparative Examples 4 to 6 Raw materials were blended and mixed according to the formulation shown in Table 3 below, melt-kneaded using a kneader, and the kneaded product was cooled, crushed, and pressed. Tableting was performed with a tablet machine to produce a resin tablet for semiconductor encapsulation. The following ingredients were used in Table 3.

Modified epoxy resin: 30 parts by weight of an epoxy resin having a dicyclopentadiene skeleton (epoxy equivalent: 260, softening point: 65 ° C.) and cresol novolak type epoxy resin (epoxy equivalent: 195, softening point: 70 ° C.)
Parts by weight were heated and melted at 150 ° C., and 20 parts by weight of linear polydimethylsiloxane having an amino-modified group at both terminals (weight average molecular weight: 9000, specific gravity: 0.96) was added thereto, followed by a crosslinking reaction for about 5 hours After the reaction, the mixture was cooled and pulverized.

Epoxy resin, modified phenol resin, phenol resin, curing catalyst, crystalline silica powder, fused silica powder, bromide epoxy resin, coupling agent: These are the same as the compounding materials used in Table 1 above.

[0069]

[Table 3]

The test shown in Table 2 was performed using the resin tablet for semiconductor encapsulation prepared as described above,
Table 4 shows the results.

[0071]

[Table 4]

As is clear from the results in Table 4, the products of the present invention use a specific modified epoxy resin and a modified novolak phenol resin, so that they have high adhesion to the nickel plating frame. And the rate of occurrence of delamination is completely absent. In particular, since the modified epoxy resin subjected to the specific siloxane modification is used in the example products, it has low stress properties, and shows good results even in the thermal cycle test. In addition, when crystalline silica powder is used as the filler, it has excellent thermal conductivity, so that high thermal conductivity required for a power device can be imparted.

[0073]

Since the resin composition for semiconductor encapsulation and the semiconductor device of the present invention have the above-mentioned constitution, they have excellent frame adhesion and high thermal conductivity required for power devices. It has excellent effects.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 23/31

Claims (4)

[Claims] 1. A resin composition for encapsulating a semiconductor comprising the following components: (A) Modification by reacting a mixture of one of a biphenyl type epoxy resin and an epoxy resin having a dicyclopentadiene skeleton and a novolak type epoxy resin with dimethylpolysiloxane having an amino-modified group at both ends. Epoxy resin. (B) Silane-modified novolak phenolic resin (C) Crystalline silica 2. The resin composition for semiconductor encapsulation according to claim 1, wherein the modified epoxy resin as the component (A) is crosslinked by reaction with dimethylpolysiloxane having amino-modified groups at both ends. 3. The semiconductor encapsulation according to claim 1, wherein the silane-modified novolak phenol resin as the component (B) is a modified novolak phenol resin obtained by reacting γ-glycidoxypropyltrimethoxysilane with an amino catalyst. Resin composition. 4. A semiconductor device comprising a semiconductor element encapsulated with the resin composition for encapsulating a semiconductor according to claim 1.