JP2002265884A - Die-attaching paste and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a die-attaching paste for adhering a semiconductor device, excellent in resistance to solder cracking. SOLUTION: This die-attaching paste contains (A) an (meth)acrylate-modified polyisoprene, (B) a compound having at least one methacryl or acryl group in its molecule, (C) a radical polymerization catalyst, and (D) a filler as essential ingredients.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a die attach paste for bonding a semiconductor having a low elastic modulus and a semiconductor device.

[0002]

2. Description of the Related Art In recent years, the production volume of semiconductor devices has been steadily increasing, and accordingly, reduction of manufacturing costs has become an important issue. As a method of joining a semiconductor element and a lead frame, there is a method of using an inorganic material such as a gold-silicon eutectic as an adhesive. However, since the cost is high and the semiconductor element may be broken by thermal stress, an organic material is used. A method using a die attach paste (paste-like adhesive) in which a filler is dispersed in a material such as the above has become mainstream.

[0003] On the other hand, solder crack resistance is particularly important for the reliability of a semiconductor device, but a die attach paste used for bonding a semiconductor element to a lead frame also improves the solder crack resistance of the semiconductor device. For,
In order to reduce the difference in the coefficient of linear expansion between the semiconductor element and the lead frame, a low elastic modulus is required. Conventionally, a die attach paste using a low-stress material such as rubber has been known, but a die attach paste with a further lower elastic modulus has been demanded in order to improve the solder crack resistance of a semiconductor device.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a die attach paste for bonding a semiconductor having a low modulus of elasticity and a semiconductor device having excellent solder crack resistance.

[0005]

The present invention provides (A) a (meth) acryl-modified polyisoprene, (B) a compound having at least one methacrylic or acrylic group in one molecule, (C) a radical polymerization catalyst, (D) A die attach paste containing a filler as an essential component. A more preferred embodiment is a die attach paste in which the (meth) acryl-modified polyisoprene is a compound obtained by reacting a maleated polyisoprene with an esterified product of an aliphatic dialcohol of (meth) acrylic acid. Further, it is a semiconductor device manufactured using the above-mentioned die attach paste.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The (meth) acryl-modified polyisoprene (A) used in the present invention imparts flexibility to a cured product of a die attach paste, and a flexible cured product can be used in a wide temperature range. It has been found that good adhesiveness is exhibited. For example, in the case of an inflexible cured product having an increased crosslink density, the cured product has a high cohesive force, but it is difficult to exhibit good adhesive strength at the interface with a lead frame or a die. A compound obtained by reacting a maleated polyisoprene with an esterified product of an aliphatic dialcohol of (meth) acrylic acid is preferred.

[0007] The compound (B) having at least one methacrylic group or acrylic group in one molecule used in the present invention increases the viscosity if only the component (A) is used, and deteriorates the workability as a die attach paste. When the component (B) is added, the viscosity of the die attach paste is adjusted,
We found that workability could be improved. It has also been found that by having a methacrylic group or an acrylic group, compatibility with the component (A) increases, and further improvement in curability can be expected.

The component (B) includes, for example, alicyclic (meth) acrylates, aliphatic (meth) acrylates, aromatic (meth) acrylates and the like. Examples include, but are not limited to, 6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate, lauryl acrylate, stearyl acrylate, phenoxyethyl methacrylate, and the like. These can be used alone or in combination.

The amount of the component (A) used in the present invention is 10 to 90 in the total weight of the components (A) and (B).
%, Preferably 30 to 30% by weight.
80% by weight. If the amount is less than 10% by weight, the adhesiveness is deteriorated. If the amount exceeds 90% by weight, the viscosity of the die attach paste is increased, which causes a problem in workability. The component (B) used in the present invention preferably contains 10 to 90% by weight based on the total weight of the components (A) and (B). If the amount is less than 10% by weight, the viscosity of the die attach paste is high, and the workability is deteriorated. If the amount is more than 90% by weight, a problem occurs in adhesiveness, which is not preferable.

The radical polymerization catalyst (C) used in the present invention is not particularly limited as long as it is a catalyst usually used for radical polymerization. However, it is preferable that a rapid heating test (1 g of a sample be placed on an electric heating plate) be used. Decomposition temperature when heated at 4 ° C./min).
Those which become 0 ° C. are preferred. If the decomposition temperature is less than 40 ° C., the storage stability of the die attach paste at room temperature becomes poor, and if it exceeds 140 ° C., the curing time becomes extremely long, which is not preferable.

Specific examples of the catalyst satisfying the above conditions include 1,1-bis (t-butylperoxy) -2-methylcyclohexane, t-butylperoxy neodecanoate, dicumyl peroxide and the like. However, these may be used alone or in combination of two or more to control the curability. Furthermore, it is also possible to add various polymerization inhibitors in advance to improve the storage stability of the die attach paste. The compounding amount of the radical polymerization catalyst (C) is 100% of the total weight of the components (A) and (B).
0.1 to 10 parts by weight based on parts by weight is preferred. 10
If the amount is more than 0.1 parts by weight, the change of the viscosity of the die attach paste with the passage of time becomes large, causing a problem in workability.

Examples of the filler (D) used in the present invention include conductive fillers such as silver powder, gold powder, nickel powder, and copper powder, and insulating fillers such as aluminum nitride, calcium carbonate, silica, and alumina. Silver powder is preferred as the conductive filler, and silica is preferred as the insulating filler. The blending amount of these fillers is not particularly limited, but is preferably 20 to 95% by weight in the whole die attach paste. If the amount is less than 20% by weight, the adhesive strength tends to decrease. If the amount exceeds 95% by weight, the viscosity of the die attach paste tends to increase, and the workability of the die attach paste tends to decrease, which is not preferable.

Silver powder is used for imparting conductivity, and the content of ionic impurities such as halogen ions and alkali metal ions is preferably 10 ppm or less. As the shape of the silver powder, flakes, dendrites, spheres and the like are used. The particle size of the silver powder used varies depending on the required viscosity of the die attach paste, but usually the average particle size is preferably 2 to 10 μm, and the maximum particle size is preferably 50 μm or less. If the average particle diameter is less than 2 μm, the viscosity of the die attach paste becomes high, and if it exceeds 10 μm, bleeding occurs because the resin component flows out during application or curing, which is not preferable. If the maximum particle size exceeds 50 μm, it is not preferable because needle clogging occurs when the die attach paste is applied with a dispenser. Also, a mixture of relatively coarse silver powder and fine silver powder can be used, and various shapes may be conveniently mixed.

The silica, which is one of the insulating fillers, preferably has an average particle size of 1 to 20 μm and a maximum particle size of 50 μm or less. If the average particle size is less than 1 μm, the viscosity of the die attach paste increases, and if the average particle size exceeds 20 μm, bleeding occurs because the resin component flows out during coating or curing, which is not preferable. If the maximum particle size exceeds 50 μm, it is not preferable because needle clogging occurs when the die attach paste is applied with a dispenser. Furthermore, a mixture of relatively coarse silica and fine silica can be used, and various shapes may be conveniently mixed.

The die attach paste of the present invention contains a coupling agent, an antifoaming agent, a surfactant,
Additives such as elastomers can be used. As a method for producing the die attach paste of the present invention, for example,
There is a method in which each raw material is premixed, kneaded using a three-roll or the like, and then deaerated under vacuum to obtain a die attach paste. As a method of manufacturing a semiconductor device using the die attach paste of the present invention, a known method can be used.

[0016]

The present invention will be specifically described below with reference to examples. <Examples 1 and 2 and Comparative Examples 1 and 2> As the component (A),
Methacryl-modified polyisoprene (number average molecular weight: about 25
000, manufactured by Kuraray Co., Ltd., UC-1), and as the component (B), lauryl acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.)
NK ester LA), dicumyl peroxide (decomposition temperature in rapid heating test: 126) as component (C)
° C, Nippon Oil & Fats Co., Ltd., Parkmill D), flake silver powder as component (D) (average particle size 3 μm, maximum particle size 20 μm)
m), crushed silica (average particle size 3 μm, maximum particle size 16 μm)
m), an alkoxysilane (KBM-403E, manufactured by Shin-Etsu Chemical Co., Ltd.) as a coupling agent at a ratio shown in Table 1 and kneading using a three-roll mill to obtain a die attach paste after defoaming. . The obtained die attach paste was evaluated by the following method. In Comparative Examples, diglycidyl bisphenol A type epoxy resin (epoxy equivalent: 180, liquid at room temperature, hereinafter referred to as bis-A epoxy), cresyl glycidyl ether (epoxy equivalent: 185, hereinafter CG) obtained by reaction of bisphenol A with epichlorohydrin
E), phenol novolak resin (hydroxyl equivalent: 104,
Softening point 85 ° C, hereinafter PN), 2-phenyl 4,5-dihydroxymethylimidazole (manufactured by Shikoku Chemical Industry Co., Ltd.)
Cureazole 2PHZ), acrylic-modified polybutadiene (number average molecular weight: about 1000, manufactured by Nippon Petrochemical Co., Ltd.)
MM-1000-80).

<Evaluation method> Elastic modulus: A test piece of 10 × 150 × 0.1 mm was prepared (hardening conditions: 175 ° C., 30 minutes), a load-displacement curve was measured by a tensile test, and the elastic modulus was obtained from the initial gradient ( (Measurement length: 100 mm, test speed: 1 mm / min, measurement temperature: 25 ° C.). Solder crack resistance: The following lead frame (copper) and silicon chip (6 × 6 mm 2) were cured and bonded at 175 ° C. for 30 minutes using the die attach paste having the compounding ratio shown in Table 1. Then, using a sealing material of Sumicon EME-7026 (manufactured by Sumitomo Bakelite Co., Ltd.), the sealed package (QFP) was placed in an atmosphere of 60 ° C. and 60% relative humidity.
After a moisture absorption treatment for 92 hours, IR reflow (260 ° C., 1
0 second), the number of internal cracks was measured by cross-sectional observation, and the index was used as an index of solder crack resistance.

Table 1 shows the evaluation results.

[Table 1]

[0019]

The die attach paste of the present invention has a characteristic of a low elastic modulus, and a semiconductor device using this has the following characteristics.
Since the solder crack resistance is excellent, a highly reliable semiconductor device can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) H01L 21/52 H01L 21/52 EF term (Reference) 4J011 PA04 PA08 PA13 PB27 PC02 4J027 AA04 BA07 BA19 CA12 CA15 CA18 CB04 CD06 CD09 4J040 CA091 CA092 FA141 FA142 FA151 FA152 FA161 FA162 FA231 FA232 GA02 HA066 HA136 HA196 HA206 HA306 HB41 JA01 JA12 JB02 KA16 KA42 LA08 LA09 MA02 MA04 MB05 NA20 5F047 AA11 BA23 BA26 BA33 BA53 BA54 BB11 DA03 DA03 DA03 DA03 DA03 DA03 DA03 DA05

Claims (3)

[Claims] 1. An essential component is (A) a (meth) acryl-modified polyisoprene, (B) a compound having at least one methacryl or acrylic group in one molecule, (C) a radical polymerization catalyst, and (D) a filler. A die attach paste characterized by being a component. 2. The diamond according to claim 1, wherein (A) the (meth) acryl-modified polyisoprene is a compound obtained by reacting a maleated polyisoprene with an esterified product of an aliphatic dialcohol of (meth) acrylic acid. Touch paste. 3. A semiconductor device manufactured using the die attach paste according to claim 1.