JPH11189763A - Die attach paste - Google Patents

Abstract

(57) [Problem] To provide a die attach paste that maintains excellent stress resistance and solder crack resistance and can be cured even in a very short time. SOLUTION: (A) hydroxyalkylacrylic acid,
Polyalkylene glycol, urethane diacrylate obtained by reacting diisocyanate, (B) monoacrylate having the following structure (1), (C) phosphate group-containing acrylate or methacrylate having the following structure (2) or (3), A die attach paste comprising (D) an alkoxysilane containing an alicyclic epoxy group, (E) an organic peroxide and / or an azo compound (F) an inorganic filler as essential components. Embedded image Embedded image Embedded image

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paste for bonding a semiconductor, which is excellent in low stress property, adhesive property and quick curing property.

[0002]

2. Description of the Related Art In recent years, the production volume of semiconductor packages has been on an increasing trend, and accordingly, reduction of manufacturing costs has become an important issue. In the process of assembling a semiconductor package, there is a step of bonding a semiconductor and a lead frame with a die attach paste. The point of this step is to reduce time and cure at low temperature. The curing process is roughly classified into a batch oven method and an in-line curing method, and a normal die mount using a fast-curing paste used in-line is usually used at 150 to 200 ° C. for 30 to 60 seconds. Done between. However, development of a paste that can be cured at a lower temperature for a shorter time is desired in the future.

On the other hand, the reliability as a package is particularly important for solder crack resistance, while the die attach paste is particularly important for low stress resistance. Epoxy resin, cyanate resin, bismaleimide resin, etc. are known as the base resin of the die attach paste. However, for example, there is no material which can be cured within 30 seconds and maintains characteristics suitable for solder crack resistance. Had not been found. Further, even if the properties were satisfied, there was only a material which was unsuitable for use because the viscosity at room temperature increased too much.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been completed as a result of intensive studies to find a die attach paste which maintains excellent stress resistance and solder crack resistance and can be cured even in a very short time. Things.

[0005]

The present invention provides (A) a hydroxyalkyl acrylic acid, a polyalkylene glycol,
Urethane diacrylate obtained by reacting diisocyanate, (B) monoacrylate having the following structure (1), (C) phosphate group-containing acrylate or methacrylate having the following structure (2) or (3), (D) fat A die attach paste comprising an essential component of an alkoxysilane containing a cyclic epoxy group, (E) an organic peroxide and / or an azo compound (F) an inorganic filler.

[0006]

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[0007]

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[0008]

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The urethane acrylate used in the present invention is synthesized by a conventional method by reacting hydroxyalkylacrylic acid, polyalkylene glycol, and diisocyanate. Examples of hydroxyalkyl acrylic acid include 2
-Hydroxyethyl acrylate and 2-hydroxypropyl acrylate. Examples of the polyalkylene glycol include polyethylene glycol, polypropylene glycol, polybutylene glycol and the like. Examples of diisocyanates include hexamethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate and hydrogenated products thereof.

Generally, urethane diacrylate cannot be pasted as it is because of its high viscosity. Therefore, a monoacrylate containing one acrylic group is added as a diluent. Further, the monoacrylate used in the present invention is represented by the formula (1), wherein the substituent R1 contains an alicyclic and / or aromatic group and has a total carbon number of 10
It is indispensable that the number is at least. By satisfying this condition, not only the effect as a diluent but also the presence of a bulky substituent can suppress shrinkage during curing, thereby improving the bonding reliability of the interface. In the case of a substituent having 10 or more carbon atoms which does not contain an alicyclic or aromatic group, curing shrinkage can be reduced, but the adhesiveness is undesirably reduced due to the characteristics of the aliphatic hydrocarbon. As an example of the monoacrylate, in the formula (1),

[0011]

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And the like. The ratio of urethane acrylate to monoacrylate is 80/20 to 20/8 by weight.
It is preferably 0, and if it is higher than 80/20, the viscosity of the paste is too high, and the workability of coating is remarkably deteriorated. On the other hand, 20
If it is smaller than / 80, the low stress property and adhesiveness of urethane acrylate will be impaired.

Next, as the alkoxysilane containing an alicyclic epoxy group, for example, KBM-303 manufactured by Shin-Etsu Silicone is known. The total amount of the acrylate or methacrylate represented by the formulas (2) and (3) (component C) and the alkoxysilane containing an alicyclic epoxy group (component D) was set at 0.
Preferably it is from 1% to 5% by weight. 0.1%
If the amount is less than the above, no effect is exerted on the adhesiveness, and if it is more than 5%, the adhesiveness is rather reduced.

Furthermore, in the present invention, component C and component D
Is an essential component, and the present invention cannot be embodied even when one of them is applied. The composition ratio is not particularly limited, but is preferably C / D = 0.1 to 10. If the amount exceeds these ranges, the adhesiveness is sharply reduced.

Examples of the organic peroxide used in the present invention include 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanate and t-butylperoxy-2.
-Ethylhexanate, t-hexylperoxy-2-
Ethyl hexanate, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane,
1-bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane, bis (4-t-butylcyclohexyl) peroxydicarbonate, t-butylperoxyisopropyl monocarbonate, t-butylperoxy3, 5,5-trimethylhexanate and the like. Examples of azo compounds include 2,2'-azobisisobutylnitrile, 1,1'azobis (cyclohexane-1-carbonitrile), 2,2'-azobis (2,4-dimethylvaleronitrile),
Examples include 2,2′-azobis [2-methyl-N- (hydroxyethyl) propionamide] and 4,4′-azobis (4-cyanovaleric acid). These peroxides and / or azo compounds can be used alone or in combination of two or more to control curability. Further, various polymerization inhibitors can be added in advance to improve the storage stability of the resin.

The addition amount of these organic peroxides and / or azo compounds is preferably from 0.01% by weight to 5% by weight, based on the total acrylate. Changes) and workability is problematic. If the amount is less than 0.01% by weight, the curability is remarkably reduced, which is not preferable.

Examples of the inorganic filler used in the present invention include insulating fillers such as aluminum nitride, calcium carbonate, silica, and alumina, and conductive fillers such as silver powder, gold powder, nickel powder, and copper powder. May be. Further, in order to prevent needle clogging, the particle diameter of these particles is preferably 50 μm or less.

It is preferable that the amount added be in the range of 10% by weight to 90% by weight based on the total paste. When the content is less than 10% by weight, the properties (low linear expansion property, low water absorption, etc.) of the inorganic filler are low, and when the content is more than 90% by weight, the paste viscosity becomes high, which is not preferable in application workability.

In the resin paste of the present invention, the above-mentioned additives such as a polymerization inhibitor, an antifoaming agent and a surfactant can be used if necessary. In the method for producing the paste of the present invention, for example, the paste is premixed to obtain a paste using a three-roll mill or the like, and defoamed under vacuum.

[0020]

EXAMPLES Examples 1 to 6, 8 and Comparative Examples 1 to 8 2-ethylacrylic acid as urethane diacrylate,
Diacrylate UN-2500 (manufactured by Negami Kogyo) synthesized from polypropylene glycol and isophorone diisocyanate, monoacrylates shown in Tables 1 and 2, Perocta 0 as peroxide (manufactured by NOF CORPORATION) 2,2 ′ as azo compound -Azoisobutylnitrile (manufactured by Wako Pure Chemical Industries, Ltd.), PM-21 (manufactured by Nippon Kayaku Co., Ltd.) as a methacrylate among the compounds shown in Tables 1 and 2 as a phosphoric acid-containing compound, and KBM as an alkoxysilane containing an alicyclic epoxy group −
303 (manufactured by Shin-Etsu Silicone Co., Ltd.), flake-like silver powder having an average particle size of 3 μm as an inorganic filler was weighed according to the formulations shown in Tables 1 and 2, and kneaded and defoamed with a three roll to obtain a die attach paste. The characteristics were measured according to the evaluation methods described below, and are shown in Tables 1 and 2.

Evaluation Method Viscosity: 2.5 rpm at 250 ° C. using an E-type viscometer.
The viscosity in m was measured. Adhesive strength: Using a paste, a 2 × 2 mm silicon chip was mounted on a copper frame and cured in an oven at 180 ° C. for 15 minutes. Use a push-pull gauge after curing 2
The hot die shear strength at 50 ° C. was measured. Void: A glass chip of 10 mm × 10 mm was mounted on a lead frame, and after curing, a void was visually checked. Good if the void is 15% or less of the adhered area, 15%
The ones exceeding the above were regarded as defective. Peeling during WB treatment: 6 mm x 15 mm on lead frame
After the chip was mounted and cured, wire bonding was performed at 250 ° C., and the adhesion state of the pellet was observed. If there was no peeling, it was good, and if peeling was observed, it was bad. Warpage: Warpage was measured as an evaluation of low stress. Thickness 20
6mm x 15mm x 0.3m in 0 micron copper frame
A silicon chip having a thickness of 20 m was adhered using a paste at 175 ° C. for 15 seconds so that the paste thickness became 20 μm. The displacement of the chip in the longitudinal direction was measured using a contact-type surface roughness meter, and the amount of warpage was determined by the difference in height. It was measured. Package crack resistance: Sumicon EME-7320
Using a sealing material (manufactured by Sumitomo Bakelite Co., Ltd.), a package molded under the following conditions at 85 ° C. and a relative humidity of 85
% After a water absorption treatment for 168 hours, followed by IR reflow (240
C. for 10 seconds), the number of internal cracks was measured by cross-section observation, and the index was used as an index of package crack resistance. Package: 80pQFP (14 × 20 × 2mm thickness) Chip size: 7.5 × 7.5mm (only aluminum wiring) Lead frame: 42 alloy Molding: 175 ° C, 2 minutes Post-mold cure: 175 ° C, 4 hours All packages Number: 12

Example 7 A die attach paste was prepared in the same manner as in the other examples except that spherical silica having an average particle diameter of 6 μm was used as the inorganic filler. The characteristics are shown in Table 1.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

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[0026]

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Component C: a = 1, b in the general formula (3)
= 1, c = 2 Component D: Epoxy group-containing alkoxysilane (KBM-3
03 / Shin-Etsu Chemical Co., Ltd.) Coupling agent A: Epoxy group-containing alkoxysilane (KBM-403E / Shin-Etsu Silicone) Coupling agent B: Mercapto group-containing alkoxysilane (KBM-803 / Shin-Etsu Silicone) Coupling agent C: Methacryl group-containing alkoxysilane (KBM-503 / Shin-Etsu Silicone Co., Ltd.)

[0028]

Industrial Applicability The present invention is an industrially useful paste for bonding semiconductors having excellent low-stress, adhesiveness and fast-curing properties.
Furthermore, due to the low shrinkage due to the combination of the specific acrylate and the interaction of the specific coupling agent, it was possible to find an adhesive force that was not previously conceivable.

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // C08F 290/06 C08F 290/06 C08G 18/38 C08G 18/38 Z 18/48 18/48 Z

Claims (1)

[Claims] (A) a hydroxyalkyl acrylic acid,
Urethane diacrylate obtained by reacting polyalkylene glycol and diisocyanate, (B) monoacrylate having the following structure (1), (C) phosphate group-containing acrylate or methacrylate having the following structure (2) or (3), A die attach paste comprising (D) an alkoxysilane containing an alicyclic epoxy group, (E) an organic peroxide and / or an azo compound, and (F) an inorganic filler as essential components. Embedded image Embedded image Embedded image