JP2005264042A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin composition and a semiconductor device having high adhesion strength to a lead frame and excellent in solder resistance in which peeling from the lead frame does not occur in solder processing.
It includes (A) an epoxy resin, (B) a phenol resin, (C) a curing accelerator, (D) an inorganic filler, (E) an aromatic carboxylic acid, and (F) a thiophene compound. A semiconductor device comprising: an epoxy resin composition for semiconductor encapsulation, and a semiconductor element sealed using the epoxy resin composition.

Description

  The present invention relates to an epoxy resin composition for semiconductor encapsulation and a semiconductor device using the same.

  In recent years, semiconductor devices have been mainly sealed with an epoxy resin composition because of excellent balance of productivity, cost, reliability, and the like. Due to the surface mounting of the semiconductor device, the semiconductor device is suddenly exposed to a high temperature of 200 ° C. or higher in the solder dipping or solder reflow process, and the stress generated when the absorbed water vaporizes explosively causes the semiconductor element, lead frame, inner lead There is a problem that peeling occurs at the interface between each of the above-mentioned various plated joint portions and a cured product of the epoxy resin composition, or cracks are generated in the semiconductor device and the reliability is significantly lowered.

In order to improve reliability reduction due to solder processing, increase the amount of inorganic filler in the epoxy resin composition to achieve low moisture absorption, high strength, low thermal expansion, and improve solder resistance. A technique of maintaining low fluidity and high fluidity during molding using a low melt viscosity resin is becoming common.
On the other hand, in terms of reliability after soldering, the adhesiveness at the interface between a cured product of the epoxy resin composition and a substrate such as a semiconductor element or a lead frame existing inside the semiconductor device has become very important. If the adhesive strength at the interface is weak, peeling occurs at the interface with the base material after the solder treatment, and further, cracks occur in the semiconductor device due to this peeling.
Conventionally, silane coupling agents such as γ-glycidoxypropyltrimethoxysilane and γ- (methacryloxypropyl) trimethoxysilane have been added to epoxy resin compositions for the purpose of improving solder resistance. However, in recent years, in response to the increasingly demanding soldering resistance, such as an increase in reflow temperature during mounting and the appearance of pre-plating frames such as Ni-Pd and Ni-Pd-Au in correspondence with lead-free solder, The addition of these silane coupling agents alone is not enough.
As a countermeasure, a method of treating the surface of the lead frame with an alkoxysilane coupling agent (for example, see Patent Document 1) has been proposed. However, it has been found that silane coupling agents have poor heat stability and have a drawback that the effect of improving adhesion in solder-resistant treatment is reduced.

  In recent years, a method of obtaining an effect of improving adhesion to a copper alloy lead frame or the like by containing a thiophene compound such as benzothiophene (for example, see Patent Document 2) has been proposed. Then, it has been found that the effect of improving the adhesion with the pre-plating frame such as Ni—Pd, Ni—Pd—Au is insufficient, and further improvement is necessary.

JP-A-6-350,000 (pages 2 to 5) JP 2003-286392 A (pages 2 to 5)

  The present invention provides an epoxy resin composition excellent in solder resistance that does not peel off from a lead frame during solder processing, and a semiconductor device.

The present invention
[1] It includes (A) an epoxy resin, (B) a phenol resin, (C) a curing accelerator, (D) an inorganic filler, (E) an aromatic carboxylic acid, and (F) a thiophene compound. An epoxy resin composition for semiconductor encapsulation,
[2] The epoxy resin composition for semiconductor encapsulation according to [1], wherein the aromatic carboxylic acid is contained in a proportion of 0.004 to 2% by weight with respect to the total resin composition,
[3] The semiconductor according to item [1] or [2], wherein the aromatic carboxylic acid is a compound having at least two phenolic hydroxyl groups per molecule and at least one carboxylic acid per molecule. Epoxy resin composition for sealing,
[4] The epoxy for semiconductor encapsulation according to [1], [2] or [3], wherein the thiophene compound is contained in a proportion of 0.004 to 2% by weight with respect to the total resin composition. Resin composition.
[5] The epoxy resin composition for semiconductor encapsulation according to [1], [2], [3] or [4], wherein the thiophene compound is a thiophenic acid compound.
[6] A semiconductor device comprising a semiconductor element sealed using the epoxy resin composition according to any one of [1] to [5],
It is.

  The semiconductor device obtained by using the epoxy resin composition of the present invention has high adhesion strength with various lead frames including those plated with Ni, Ni—Pd, Ni—Pd—Au, etc., and has solder resistance. Is excellent.

The present invention includes (A) an epoxy resin, (B) a phenol resin, (C) a curing accelerator, (D) an inorganic filler, (E) an aromatic carboxylic acid, and (F) a thiophene compound. It is possible to obtain an epoxy resin composition excellent in solder resistance that does not peel off from the lead frame during solder processing, and a semiconductor device.
Hereinafter, the present invention will be described in detail.

  The epoxy resin used in the present invention is a monomer, oligomer, or polymer in general having two or more epoxy groups in one molecule. For example, hydroquinone type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, biphenyl. Type epoxy resin, stilbene type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, naphthol novolac type epoxy resin, triphenolmethane type epoxy resin, alkyl modified triphenolmethane type epoxy resin, dicyclopentadiene modified phenol type epoxy Resin, phenol aralkyl type epoxy resin (having phenylene skeleton, biphenylene skeleton, etc.), naphthol aralkyl type epoxy resin (having phenylene skeleton, biphenylene skeleton, etc.) That), terpene-modified phenol type epoxy resin, triazine nucleus-containing epoxy resins, but are not limited thereto. These epoxy resins may be used alone or in combination.

Examples of the phenol resin used in the present invention include monomers, oligomers and polymers having two or more phenolic hydroxyl groups in one molecule. For example, phenol novolak resin, cresol novolak resin, phenol aralkyl resin (phenylene skeleton, biphenylene). Naphthol aralkyl resin (having a phenylene skeleton, biphenylene skeleton, etc.), terpene-modified phenol resin, dicyclopentadiene-modified phenol resin, triphenolmethane phenol resin, bisphenol compound, and the like. Is not to be done. These phenol resins may be used alone or in combination of two or more.
The equivalent ratio of the epoxy groups of all epoxy resins to the phenolic hydroxyl groups of all phenol resins is preferably 0.5 to 2.0, particularly preferably 0.7 to 1.5. If it is out of the above range, curability, moisture resistance reliability and the like may be lowered.

  The curing accelerator used in the present invention can be a catalyst for a crosslinking reaction between an epoxy resin and a phenol resin. For example, amines such as tributylamine and 1,8-diazabicyclo (5,4,0) undecene-7 are used. Examples thereof include, but are not limited to, organic compounds such as triphenylphosphine and tetraphenylphosphonium / tetraphenylborate salts, and imidazole compounds such as 2-methylimidazole. These curing accelerators may be used alone or in combination.

As the inorganic filler used in the present invention, those generally used for epoxy resin compositions for semiconductor encapsulation can be used, and examples thereof include fused silica, crystalline silica, alumina, silicon nitride, aluminum nitride and the like. It is done. These inorganic fillers may be used alone or in combination.
When increasing the compounding quantity of an inorganic filler, it is common to use a fused silica. Fused silica can be used in either crushed or spherical shape, but in order to increase the blending amount of fused silica and to suppress the increase in the melt viscosity of the epoxy resin composition, it is better to mainly use spherical ones. preferable. Furthermore, in order to increase the blending amount of the fused spherical silica, it is desirable to adjust so that the particle size distribution of the fused spherical silica becomes wider. The inorganic filler that has been surface-treated with a silane coupling agent or the like in advance may be used. Although the compounding quantity of an inorganic filler is not specifically limited, 80 to 94 weight% is preferable in all the epoxy resin compositions. If the lower limit is not reached, sufficient solder resistance may not be obtained, and if the upper limit is exceeded, sufficient fluidity may not be obtained.

  The aromatic carboxylic acid used in the present invention improves the adhesiveness between the cured product of the resin composition and the lead frame, and consequently the moisture resistance reliability of the semiconductor device formed by sealing the semiconductor element with the cured product of the resin composition. It plays the role of improving reflow crack resistance. Aromatic carboxylic acid improves adhesion between hardened resin composition and non-copper lead frame (silver-plated lead frame, nickel-plated lead frame, nickel / palladium alloy pre-plating frame) Therefore, when the lead frame is used, the solder resistance of the semiconductor device is greatly improved. Although it does not specifically limit as a compounding quantity of the aromatic carboxylic acid used by this invention, It is preferable to contain in the ratio of 0.004 to 2 weight% with respect to all the epoxy resin compositions. Below the lower limit, the effect of improving the adhesion between the cured product of the resin composition and the lead frame may be insufficient, which is not preferable. On the other hand, when the above upper limit is exceeded, the fluidity of the resin composition may be lowered, which is not preferable.

  The aromatic carboxylic acid used in the present invention is not particularly limited in molecular structure, but a compound having at least two phenolic hydroxyl groups per molecule and at least one carboxylic acid per molecule, It is more preferable from the viewpoint of improving adhesion. Examples of the compound having at least two phenolic hydroxyl groups per molecule and at least one carboxylic acid per molecule include compounds represented by the following general formula (1) and general formula (2). be able to.

  The thiophene compound used in the present invention improves the adhesion between the cured product of the resin composition and the lead frame, and consequently the moisture resistance reliability of the semiconductor device formed by sealing the semiconductor element with the cured product of the resin composition, Although it plays a role in improving the reflow crack resistance, the combined use of the above aromatic carboxylic acid, in particular, the cured resin composition and the non-copper lead frame (silver plated lead frame, nickel plated lead frame, nickel / palladium alloy) Therefore, when the lead frame is used, the solder resistance of the semiconductor device is greatly improved. Although it does not specifically limit as a compounding quantity of the thiophene compound used by this invention, It is preferable to contain in the ratio of 0.004 to 2 weight% with respect to all the epoxy resin compositions. Below the lower limit, the effect of improving the adhesion between the cured product of the resin composition and the lead frame may be insufficient, which is not preferable. On the other hand, when the above upper limit is exceeded, the fluidity of the resin composition may be lowered, which is not preferable.

  The thiophene compound used in the present invention is represented by the general formula (3), and the molecular structure is not particularly limited, but is preferably a thiophenic acid compound. Examples of the thiophenic acid compound include β-thiophenic acid or thiophenetricarboxylic acid.

（式中、Ｒ₁からＲ₄は水素、或いは、−ＣＯＯＨ、−ＳＨ、−ＯＨ、−ＮＨ₂、−ＣＮから選ばれる官能基、炭素数１ないし４のアルキル基、アルケニル基、アルコキシ基、アルコキシカルボニル基、又は炭素数６〜１０のアリール基であり、互いに同一であっても異なっていてもよい。）

(Wherein R ₁ to R ₄ are hydrogen, or a functional group selected from —COOH, —SH, —OH, —NH ₂ , —CN, an alkyl group having 1 to 4 carbon atoms, an alkenyl group, an alkoxy group, An alkoxycarbonyl group or an aryl group having 6 to 10 carbon atoms, which may be the same as or different from each other.)

  In addition to the components (A) to (F), the epoxy resin composition of the present invention is optionally coupled with a silane coupling agent, a titanate coupling agent, an aluminum coupling agent, an aluminum / zirconium coupling agent, or the like. Agent, flame retardant such as brominated epoxy resin, antimony oxide, phosphorus compound, inorganic ion exchanger such as bismuth oxide hydrate, colorant such as carbon black, bengara, low stress agent such as silicone oil, silicone rubber, Various additives such as natural waxes, synthetic waxes, higher fatty acids and metal salts thereof or mold release agents such as paraffin, and antioxidants may be appropriately blended.

In the epoxy resin composition of the present invention, the components (A) to (F) and other additives are mixed using a mixer, then heated and kneaded by a kneader such as a roll, a kneader, or an extruder, and pulverized after cooling. Is obtained.
In order to seal an electronic component such as a semiconductor element and manufacture a semiconductor device using the epoxy resin composition of the present invention, it may be cured by a molding method such as a transfer mold, a compression mold, or an injection mold.

EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these. The blending unit is parts by weight.
Example 1

Epoxy resin represented by formula (4) (softening point 58 ° C., epoxy equivalent 272, hereinafter referred to as epoxy resin 1) 8.2 parts by weight

Phenol resin represented by formula (5) (softening point 107 ° C., hydroxyl group equivalent 200, hereinafter referred to as phenol resin 1) 6.0 parts by weight

1,8-diazabicyclo (5,4,0) undecene-7 (hereinafter referred to as DBU)
0.2 part by weight Fused spherical silica (average particle size 28 μm) 84.7 parts by weight

0.2 parts by weight of 2,5-dihydroxybenzoic acid (reagent) represented by the formula (6)

Β-thiophenic acid (reagent) represented by the formula (7) 0.2 parts by weight

Carnauba wax 0.2 parts by weight Carbon black 0.3 parts by weight was mixed using a mixer, then kneaded using two rolls with surface temperatures of 90 ° C. and 25 ° C., cooled and pulverized to obtain an epoxy resin composition. Got. The characteristics of the obtained epoxy resin composition were evaluated by the following methods. The results are shown in Table 1.

Evaluation method Spiral flow: Using a mold for spiral flow measurement according to EMMI-1-66, measurement was performed under conditions of a mold temperature of 175 ° C., an injection pressure of 6.9 MPa, and a curing time of 120 seconds. The unit is cm.
Adhesion strength: 2 mm x 2 mm x 2 mm adhesion on a 9 x 29 mm strip test lead frame using a transfer molding machine under conditions of a mold temperature of 175 ° C, an injection pressure of 9.8 MPa, and a curing time of 120 seconds Ten strength test pieces were molded per level. Two types of lead frames were used: a silver plated copper frame (frame 1) and a gold plated NiPd alloy frame (frame 2). Thereafter, the shear strength between the cured product of the epoxy resin composition and the frame was measured using an automatic shear strength measuring apparatus (manufactured by DAGE, PC2400). Table 1 shows the average value of the shear strength of 10 test pieces. The unit is N / mm ² .
Solder resistance: 176-pin LQFP package (package size is 24x24mm, thickness is 2.0mm, silicon chip size is 8.0x8.0mm, lead frame is 176pin pre-plating frame, NiPd alloy is Au plated Was molded by transfer molding under conditions of a mold temperature of 175 ° C., an injection pressure of 9.3 MPa, and a curing time of 120 seconds, and post-cured at 175 ° C. for 8 hours. The resulting package was humidified for 168 hours in an environment of 85 ° C. and 85% relative humidity. Thereafter, this package was immersed in a solder bath at 260 ° C. for 10 seconds. Ten packages that have been subjected to soldering were observed using an ultrasonic flaw detector, and the rate of occurrence of delamination at the interface between the chip (SiN coated product) and the cured product of the epoxy resin composition [(Peeling occurrence package Number) / (total number of packages) × 100] is expressed in%.

Examples 2-6, Comparative Examples 1-5
According to the composition of Table 1, an epoxy resin composition was obtained in the same manner as in Example 1 and evaluated in the same manner as in Example 1. These results are shown in Table 1. The details of the epoxy resin and phenol resin used are shown in Table 2. Moreover, it shows below about the other component used except Example 1. FIG.

4 ', 4 "-dihydroxy-triphenylmethane-2-carboxylic acid represented by formula (8) (hereinafter referred to as phenolphthalene)

Thiophenetetracarboxylic acid represented by formula (9)

Γ-Glycidoxypropyl trimercaptosilane represented by the formula (10)

According to Example 1, the epoxy resin composition to which 2,5-dihydroxybenzoic acid and β-thiophenic acid were added had high adhesion strength with the lead frame and excellent solder resistance. . Moreover, even if it changed the kind of resin by Example 2, high adhesion strength and the outstanding solder resistance were obtained by adding 2, 5- dihydroxy benzoic acid and (beta) -thiophenic acid. In Examples 3, 4 and 5, the addition amounts of the aromatic carboxylic acid and the thiophene compound were changed, but in both cases, adhesion strength and solder resistance comparable to those in Example 1 were obtained. Example 6 uses phenolphthaline as the aromatic carboxylic acid and thiophenetetracarboxylic acid as the thiophene compound. Example 1 uses equivalent amounts of 2,5-dihydroxybenzoic acid and β-thiophenic acid. Adhesive strength and solder resistance equivalent to
Comparative Examples 1 and 2 are systems in which an aromatic carboxylic acid and a thiophene compound are not added. However, the adhesion strength was low and the solder resistance was low regardless of the type of resin. In Comparative Examples 3 and 4, aromatic carboxylic acid or thiophene compound was used alone, but the adhesion strength with the lead frame was high, but the results of solder resistance were aromatic carboxylic acid and aromatic carboxylic acid. And the result inferior to the case where it added together and a thiophene compound was obtained. Comparative Example 5 uses γ-glycidoxypropyl trimercaptosilane, which has been conventionally used as an additive for improving solder resistance, but has weak adhesion strength with a lead frame. The results of solder resistance were inferior to the case of adding aromatic carboxylic acid.

  The semiconductor device obtained by using the epoxy resin composition of the present invention has high adhesion strength with various lead frames including those plated with Ni, Ni—Pd, Ni—Pd—Au, etc., and has solder resistance. Therefore, it can be suitably used for power transistors, VLSI, and the like.

Claims (6)

(A) An epoxy resin, (B) a phenol resin, (C) a curing accelerator, (D) an inorganic filler, (E) an aromatic carboxylic acid, and (F) a thiophene compound. Stopping epoxy resin composition. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the aromatic carboxylic acid is contained in a proportion of 0.004 to 2% by weight with respect to the total resin composition. The epoxy resin composition for semiconductor encapsulation according to claim 1 or 2, wherein the aromatic carboxylic acid is a compound having at least two phenolic hydroxyl groups per molecule and at least one carboxylic acid per molecule. . The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the thiophene compound is contained in a proportion of 0.004 to 2% by weight with respect to the total resin composition. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the thiophene compound is a thiophenic acid compound. A semiconductor device comprising a semiconductor element sealed with the epoxy resin composition according to claim 1.