JPH1161086A - Die-attach resin paste for semiconductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a die-attach resin paste improved in resistances to staining and soldering cracks by compounding a specific urethane (meth)acrylate resin with a specific (meth)acrylic resin, an org. peroxide and an inorg. filler. SOLUTION: 100 pts.wt. urethane (meth)acrylate resin represented by formula I or II (wherein R1 is H or CH3 ; and m and n are each an integer) and obtd. by reacting polypropylene glycol with isophorone diisocyanate and then with hydroxyethyl (meth)acrylate is compounded with 50-200 pts.wt. (meth)acrylic resin represented by formula III (R2 is H or CH3 ; and k is 10 or lower), 0.1-50 pts.wt. org. peroxide, 50-1,200 pts.wt. inorg. filler and required amts. of additives such as an antifoaming agent, a coupling agent and a surfactant. Thus is obtd. a die-attach resin paste for semiconductors which hardly causes staining of a substrate due to outgassing during curing and which forms a void-free cured layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin paste for bonding a semiconductor element such as an IC or an LSI to a substrate or the like.

[0002]

2. Description of the Related Art With the remarkable development of the electronics industry in recent years, the degree of integration of circuits in transistors, ICs, LSIs, VLSIs and semiconductor devices has been rapidly increasing.
For this reason, the size of the semiconductor element has been dramatically increased to about several tens mm, whereas the long side in the related art was about several mm.
In addition, the lead frame is mainly made of inexpensive copper material having good thermal conductivity from the conventional 42 alloy. On the other hand, the mounting of semiconductor products has become a surface mounting method, and the size of the semiconductor products themselves, that is, packages, has become smaller and thinner for high-density mounting.

[0003] In accordance with the trend of such semiconductor products, the required performance of constituent materials of the semiconductor products has changed, and the bonding paste that has been conventionally required for the die bonding resin paste for bonding the semiconductor element and the metal frame has been changed. Not only reliability, but also stress relaxation characteristics to absorb and relax thermal stress based on the difference in thermal expansion coefficient between large chip and copper frame,
Further, solder crack resistance based on surface mounting in a thin package has been demanded.

[0004] Conditions for such a solder crack-resistant resin paste for die bonding include items such as low stress, low water absorption and low contamination. Among these items, extensive research and development on low stress properties and low water absorption, such as resins, curing agents, and additives, have been made and put to practical use. On the other hand, regarding the contamination, the resin paste for die bonding is generally composed of a resin and an inorganic filler, but the viscosity of the paste is limited in consideration of the coating workability.

When a conventional epoxy resin is used, since the resin is originally a viscous liquid or solid, it is necessary to lower the viscosity by adding a diluent to form a paste. Examples of the diluent include a reactive diluent such as monoepoxy and aliphatic polyepoxy, and a non-reactive diluent represented by a solvent.

In the case of a reactive diluent, a part of the paste is volatilized as an outgas during the curing of the paste, which easily contaminates the substrate, chip surface and the like. The adhesion between the resin and the substrate or chip surface deteriorates, the low stress properties used in the sealing resin composition and paste cannot be utilized, and the interface peels and package cracks when stress is applied tend to occur. there were. Although not related to the solder cracking property, the reactive diluent is easily volatilized and generally has a problem in the working environment. For this reason, there is a problem that exhaust must be sufficiently performed at the time of curing, which is not preferable from an environmental point of view. On the other hand, when the non-reactive diluent is used, there is almost no contamination on the substrate and the chip, but there are problems such as easy generation of voids in the paste layer and uneven thickness of the paste.

Further, there are combinations of liquid epoxy resin, liquid hardener, silver powder and other components. However, in general, when applying the paste to the lead frame, stringing failure is likely to occur. There was a problem. Therefore, there has been a demand for the development of a paste which does not contain a diluent or solvent and has low contamination and excellent solder crack resistance.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a resin paste for die bonding which is excellent in low contamination and solder crack resistance.

[0009]

The present invention provides (A) a urethane acrylate resin or a urethane methacrylate resin represented by the following general formula (1) or (2), and (B) an acrylic resin represented by the following general formula (3). Resin or methacrylic resin, (C) an organic peroxide, and (D) an inorganic filler as essential components, and 100 parts by weight of the component (A) and the component (B)
Is 50 to 200 parts by weight, the component (C) is 0.1 to 50 parts by weight, and the component (D) is 50 to 1200 parts by weight.

[0010]

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[0011]

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[0012]

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The urethane acrylate resin or urethane methacrylate resin represented by the formula (1) or (2) used in the present invention has a characteristic of a low elastic modulus. The reaction product of polypropylene glycol and isophorone diisocyanate is further reacted with hydroxyethyl acrylate or hydroxyethyl methacrylate.

The acrylic resin or methacrylic resin represented by the formula (3) according to the present invention is used in an amount of 100 parts by weight of the urethane acrylate resin or the urethane methacrylate resin represented by the general formula (1) or (2). 50 ~
Preferably it is 200 parts by weight. When the amount is less than 50 parts by weight, the effect of diluting and low viscosity is small and the viscosity of the paste becomes too high, and the coating workability is lowered.
Exceeding the parts by weight increases the outgas generated at the time of curing, thereby impairing the contamination and deteriorating the solder crack resistance. In the formula (3), the number of k is preferably 10 or less. When the number of k exceeds 10, the water absorption increases, and the adhesive strength after moisture absorption decreases, which is not preferable.

The organic peroxide used in the present invention is not particularly limited. For example, 1,1,3,3-
Tetramethylbutyl peroxy-2-ethyl hexanate, t-butyl peroxy-2-ethyl hexanate,
t-hexylpa-oxy-2-ethorhexanate,
1,1-bis (t-butylperoxy) -3,3,5-
Trimethylcyclohexane, 1,1-bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane, bis (4-t-butylcyclohexyl) peroxydicarbonate and the like can be mentioned. These peroxides can be used alone or in combination of two or more to control curability.

The amount of the organic peroxide is 0.1 to 100 parts by weight of the urethane acrylate resin or urethane methacrylate resin represented by the formula (1) or (2).
It is preferably from 50 to 50 parts by weight. If the amount is less than 0.1 part by weight, the curing reaction becomes too slow and sufficient adhesive strength is not obtained, and if it is more than 50 parts by weight, the storage stability decreases, which is not preferable. Further, various polymerization inhibitors can be added in advance in order to improve the storage stability of the resin.

Examples of the inorganic filler used in the present invention include insulating fillers such as calcium carbonate, silica, and alumina, and conductive fillers such as silver powder, gold powder, nickel powder, and copper powder. . In order to further prevent needle clogging, these particle sizes are 50 μm
The following is preferred. The amount of the inorganic filler is 50 parts by weight based on 100 parts by weight of the urethane acrylate resin or the urethane methacrylate resin represented by the formula (1) or (2).
It is preferably from 1,200 parts by weight. If the amount is less than 50 parts by weight, the heat conductivity is insufficient or the conductivity is insufficient. If the amount is more than 1200 parts by weight, the viscosity of the paste increases and the coating workability decreases, which is not preferable.

In the resin paste of the present invention, additives such as an antifoaming agent, a coupling agent and a surfactant can be used as required. The method for producing the paste of the present invention includes, for example, pre-mixing to obtain a paste using a three-roll mill or the like, followed by defoaming under vacuum.

[0019]

The present invention will be specifically described below with reference to examples. The mixing ratio is part by weight.

Examples 1 to 6-As a monofunctional urethane acrylate resin, UN-2111A (component A) manufactured by Negami Kogyo Co., Ltd.-As an acrylate resin of formula (3), AMP-20G manufactured by Shin-Nakamura Chemical Co., Ltd. (B component)-1,1,3,3-tetramethylbutylperoxy-2-ethylhexanate (C component)-Flaky silver powder with an average particle size of 3 µm (D1 component)-Spherical silica filler with an average particle size of 6 µm (D2 component) Bisphenol F diglycidyl ether (E component) Tertiary butyl phenyl glycidyl ether (F
Ingredients)-Butyl cellosolve acetate (G component)-Phenol novolak resin (H component)-2-Phenyl-4-methylimidazole (I component) is blended in the ratio shown in Table 1, and thoroughly kneaded with three rolls.
After defoaming, a resin paste was obtained, and various performances were evaluated. Table 1 shows the evaluation results.

Comparative Examples 1 to 6 Resins were mixed in the proportions shown in Table 2 to obtain resin pastes in the same manner as in the examples, and various performances were evaluated in the same manner as in the examples.
Table 2 shows the evaluation results.

Evaluation method Viscosity: 2.5 rpm at 25 ° C. using an E-type viscometer.
The viscosity at rpm 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 150 ° C. for 30 minutes. After curing, the die shear strength under heat at 250 ° C. (before water absorption) was measured using a push-pull gauge. The cured sample was taken at 85 ° C, 85% relative humidity, 7
Water absorption treatment was performed for 2 hours, and the hot die shear strength at 240 ° C. (after water absorption) was measured. Water absorption: paste 50 × 50 on Teflon sheet
× 0.1 mm and cured in an oven at 200 ° C. for 60 minutes, then 85 ° C., relative humidity 85%, 72
Water absorption treatment was performed for a time, and the water absorption was calculated from the weight change before and after the treatment. Void: A glass chip of 10 mm × 10 mm was mounted on a lead frame, and after curing, voids were visually checked. Good if the void is 15% or less of the adhered area, 1
Those exceeding 5% were regarded as defective. Peeling during WB treatment: 6 mm x 15 mm on lead frame
After mounting and hardening the chip, a wire-bonding treatment 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. 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 Number of packages: 12

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

According to the present invention, the reactive diluent and solvent used in the conventional epoxy resin are not contained, so that there is almost no contamination of the substrate due to outgas at the time of curing, and voids are generated in the cured product layer. None, and has excellent solder crack resistance.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 33/08 C08L 33/08

Claims (1)

[Claims] (A) a urethane acrylate resin or a urethane methacrylate resin represented by the following general formula (1) or (2); (B) an acrylic resin or methacryl resin represented by the following general formula (3); (C) Organic peroxides,
(D) An inorganic filler is an essential component, and component (A) 100
Component (B) is 50 to 200 parts by weight, component (C) is 0.1 to 50 parts by weight, and component (D) is 50 to 1 part by weight based on parts by weight.
200 parts by weight of die attach resin paste for semiconductor. Embedded image Embedded image Embedded image