Curable resin composition and sealing material using same

Abstract

The present invention aims to provide a resin composition containing a cyanate ester compound which can reduce the formation of carbamate compounds so that the resin composition can be suitably used as an sealing material. The present invention relates to a curable resin composition containing a cyanate ester compound and a dehydrating agent.

Claims

1. A curable resin composition, comprising: a cyanate ester compound; a maleimide compound; and a dehydrating agent, wherein the dehydrating agent comprises a carbodiimide compound; and a siloxane compound represented by the following average composition formula (6):
XaYbZcSiOd   (6), wherein each X is the same or different and represents an organic structure containing an imide bond; each Y is the same or different and represents at least one selected from the group consisting of a hydrogen atom, a hydroxy group, a halogen atom, and an OR group; each Z is the same or different and represents an organic group containing no imide bond; each R is the same or different and represents at least one selected from the group consisting of an alkyl group, an acyl group, an aryl group, and an unsaturated aliphatic residue, and may have a substituent; a, b, and c each represent 0 or a number of less than 3; d represents a number of less than 2, excluding 0; and a+b+c+2d=4, wherein the cyanate ester compound is represented by the following formula (1): ##STR00018## wherein R.sup.1 and R.sup.2 are the same as or different from each other and each represents a hydrogen atom, a C1-C4 alkyl group, a halogenated alkyl group, or a halogen group (X); each R.sup.3 is the same as or different from each other and represents an organic group represented by any of the chemical formulas below; each R.sup.4 is the same as or different from each other and represents an organic group represented by the chemical formula below; m.sup.1 is 0 or 1; and n.sup.1 represents an integer of 0 to 10 ##STR00019## the amount of the cyanate ester compound is from 15% to 36% by mass based on 100% by mass of the total organic component in the curable resin composition, the amount of the carbodiimide compound present is from 1.5% to 5% by mass based on 100% by mass of the cyanate ester compound in the curable resin composition, and the amount of the siloxane compound is from 74% to 189% by mass based on 100% by mass of the cyanate ester compound in the curable resin composition.

2. The curable resin composition according to claim 1, wherein the dehydrating agent is polycarbodiimide.

3. A sealing material, comprising the curable resin composition according to claim 1.

4. An automobile component, comprising a cured product of the curable resin composition according to claim 1.

5. The curable resin composition according to claim 1, wherein the carbodiimide compound is at least one selected from the group consisting of N,N′-diphenylcarbodiimide, N,N′-di-2,6-dimethylphenylcarbodiimide, N,N′-di-o-toluylcarbodiimide, N,N′-di-p-toluylcarbodiimide, N,N′-di-p-nitrophenylcarbodiimide, N,N′-di-p-aminophenyl-carbodiimide, N,N′-di-p-hydroxyphenylcarbodiimide, N,N′-di-p-chlorophenylcarbodiimide, N,N′-di-o-chlorophenyl-carbodiimide, N,N′-di-3,4-dichlorophenylcarbodiimide, N,N′-di-2,5-dichlorophenylcarbodiimide, N,N′-p-phenylene-bis-o-toluylcarbodiimide, N,N′-p-phenylene-bis-dicyclohexylcarbodiimide, N,N′-p-phenylene-bis-di-p-chlorophenylcarbodiimide, N,N′-2,6,2′,6′-tetraisopropyl-diphenylcarbodiimide, N,N′-ethylene-bis-diphenyl-carbodiimide, N-toluyl-N′-cyclohexylcarbodiimide, N,N′-di-2,6-diisopropylphenylcarbodiimide, N,N′-di-2,6-di-tert-butylphenylcarbodiimide, N-toluyl-N′-phenylcarbodiimide, N,N′-benzylcarbodiimide, N-octadecyl-N′-phenylcarbodiimide, N-benzyl-N′-phenylcarbodiimide, N-octadecyl-N′-tolylcarbodiimide, N-cyclohexyl-N′-tolylcarbodiimide, N-phenyl-N′-tolylcarbodiimide, N-benzyl-N′-tolylcarbodiimide, N,N′-di-o-ethylphenylcarbodiimide, N,N′-di-p-ethylphenyl-carbodiimide, N,N′-di-o-isopropylphenylcarbodiimide, N,N′-di-p-isopropylphenylcarbodiimide, N,N′-di-o-isobutylphenyl-carbodiimide, N,N′-di-p-isobutylphenylcarbodiimide, N,N′-di-2,6-diethylphenylcarbodiimide, N,N′-di-2-ethyl-6-isopropylphenylcarbodiimide, N,N′-di-2-isobutyl-6-isopropylphenylcarbodiimide, N,N′-di-2,4,6-trimethylphenyl-carbodiimide, N,N′-di-2,4,6-triisopropylphenylcarbodiimide, N,N′-di-2,4,6-triisobutylphenylcarbodiimide, poly(4,4′-diphenylmethanecarbodiimide), poly(3,3′-dimethyl-4,4′-diphenylmethanecarbodiimide), poly(naphthylene-carbodiimide), poly(p -phenylenecarbodiimide), poly(m-phenylenecarbodiimide), poly(tolylcarbodiimide), poly(methyldiisopropyl-phenylenecarbodiimide), poly(triethylphenylenecarbodiimide), poly(triisopropylphenylenecarbodiimide), and a (poly)carbodiimide prepared using tetramethylxylylene diisocyanate as feedstock.

6. The curable resin composition according to claim 1, wherein the carbodiimide compound is a polycarbodiimide prepared using tetramethylxylylene diisocyanate as feedstock.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1-1 illustrates the results of an ultrasonic test of a semiconductor package including the resin composition of Comparative Example 1 as an sealing material immediately after molding.

(2) FIG. 1-2 illustrates the results of an ultrasonic test of a semiconductor package including the resin composition of Comparative Example 1 as an sealing material after post-curing.

(3) FIG. 2-1 illustrates the results of an ultrasonic test of a semiconductor package including the resin composition of Example 1 as an sealing material immediately after molding.

(4) FIG. 2-2 illustrates the results of an ultrasonic test of a semiconductor package including the resin composition of Example 1 as an sealing material after post-curing.

DESCRIPTION OF EMBODIMENTS

(5) Hereinafter, the present invention is described in greater detail with reference to examples, but is not limited thereto. Unless otherwise specified, “part(s)” means “part(s) by weight”, and “%” means “% by mass”.

(6) <Measurement of Molecular Weight>

(7) The number average molecular weight and weight average molecular weight of siloxane compounds can be determined by gel permeation chromatography (GPC) under the following measurement conditions.

(8) Measuring equipment: HLC-8120GPC (trade name, from Tosoh Corporation)

(9) Molecular weight column: TSK-GEL GMHXL-L and TSK-GEL G5000HXL (both from Tosoh Corporation) connected in series

(10) Eluent: Tetrahydrofuran (THF)

(11) Reference material for calibration curve: Polystyrene (from Tosoh Corporation)

(12) Measuring method: An object to be measured was dissolved in THF to give a solids content of about 0.2% by mass, and the solution is filtered to obtain a filtrate as a measurement sample, which was then measured for molecular weight.

(13) <Measurement of Glass Transition Temperature (Tg)>

(14) The glass transition temperature of resin compositions was measured using a dynamic viscoelasticity measuring device (device name: DMA 7100, from Hitachi High-Tech Science Corporation). The measurement was carried out at a temperature in the range of −100° C. to 400° C. and a rate of temperature increase of 5° C./min in a nitrogen atmosphere.

Synthesis Example 1

Synthesis of poly{γ-(5-norbornene-2,3-imido)-propylsilsesquioxane}

(15) A 500 mL four-necked flask equipped with a stirrer, a temperature sensor, and a condenser was charged with 87.9 g of diglyme previously dried with molecular sieves and 142.5 g of 3-aminopropyltrimethoxysilane, and they were heated to 100° C. with stirring under dry nitrogen flow to remove moisture in the system. Then, while the temperature of the reaction solution was still maintained at 1000° C., 131.8 g of 5-norbornene-2,3-dicarboxylic anhydride was introduced in four portions over 30 minutes. Nine hours after the completion of the introduction, high performance liquid chromatography was performed to confirm complete consumption of 5-norbornene-2,3-dicarboxylic anhydride.

(16) Subsequently, 42.9 g of deionized water was introduced in one portion, and the mixture was heated to reflux by-product methanol in the condenser, and then maintained at 95° C. for 10 hours. Thereafter, the condenser was replaced with a partial condenser and heating was started again. The temperature of the reaction solution was allowed to reach 120° C. over 3 hours while by-product methanol and condensed water were recovered. At the time when the temperature reached 120° C., 0.65 g of cesium carbonate was introduced and heating was directly started. The temperature was allowed to reach 160° C. over 3 hours while condensed water was recovered, and this temperature was maintained for 2 hours, followed by cooling to room temperature to give a reaction product A.

(17) The reaction product A was a dark brown, highly viscous liquid with a non-volatile content of 70.0%, and had a number average molecular weight of 2340 and a weight average molecular weight of 2570 as determined by GPC. The reaction product was analyzed by .sup.1H-NMR and .sup.13C-NMR to confirm that it contained a compound (siloxane compound 1) represented by the following formula (10).

(18) .sup.1H-NMR: 0.25-0.45 (bs, 2H), 1.2-1.45 (bs, 2H), 1.47 (dd, 2H), 3.0-3.2 (bs, 4H), 3.4-3.6 (bs, 2H), 5.8-6.0 (bs, 2H) .sup.13C-NMR: 9.7, 21.5, 40.4, 44.9, 45.7, 50.1, 134.2, 178.0

(19) ##STR00015##

Synthesis Example 2

Synthesis of poly{(cis-4-cyclohexene-1,2-imido)-propylsilsesquioxane}

(20) A reaction product B was prepared as in Synthesis Example 1, except that 122.2 g of cis-4-cyclohexene-1,2-dicarboxylic anhydride was used instead of 131.8 g of 5-norbornene-2,3-dicarboxylic anhydride in Synthesis Example 1. The reaction product B was a dark brown, highly viscous liquid with a non-volatile content of 70.0%, and had a number average molecular weight of 2041 and a weight average molecular weight of 2838 as determined by GPC. The reaction product was analyzed by .sup.1H-NMR and .sup.13C-NMR to confirm that it contained a compound (siloxane compound 2) represented by the following formula (11).

(21) .sup.1H-NMR: 0.25-0.55 (bs, 2H), 1.3-1.5 (bs, 2H), 2.0-2.5 (dd, 4H), 2.9-3.1 (bs, 2H), 3.2-3.35 (bs, 2H), 5.65-5.8 (bs, 2H) .sup.13C-NMR: 10.0, 21.0, 23.8, 39.0, 41.1, 127.8, 180.5

(22) ##STR00016##

Examples 1 to 4 and Comparative Examples 1 and 2

(23) The materials were weighed as shown in Table 1 below, and then kneaded using a hot roll mill to give a compound. The temperature of the surface of the milling roll was set at 72° C., and the kneading time was set at 5 minutes. The compound was ground into powder with a particle size of 1 mm or smaller using a grinding mill and then formed into tablets having a diameter of 18 mm and a weight of 7 g using a tablet machine.

(24) The tablets of the resin composition were evaluated for sealing material properties as described below. Furthermore, a semiconductor package was prepared, and the degree of separation of the sealing material was determined for the semiconductor package to evaluate the reliability of the sealing material as described below.

(25) <Evaluation of Sealing Material Properties (Handleability)>

(26) The tablets of the resin composition were put in a plastic bag and left at 40° C. for 24 hours. Then, the tablets were taken out from the bag, and their conditions were observed. Tablets that were initially distorted in shape and fused to each other so that they were not separable from each other were rated “bad”; tablets that adhered to each other but were not distorted in shape and were easily separable from each other were rated “good”; and tablets that showed no adhesion and remained completely the same as before being left under the above conditions were rated “excellent”.

(27) In addition, the sealing material was sandwiched between hot plates maintained at 180° C. and press molded at 5 MPa for 300 seconds to prepare a 2 mm thick sheet. The sheet was left in an oven at 270° C. for 5 hours to prepare a molded sheet. The dynamic viscoelasticity of the molded sheet was measured to determine the Tg. The measurement was carried out using a DMA7100 device produced by Hitachi High-Tech Science Corporation at temperatures of −100° C. to 400° C. under nitrogen gas flow at a scanning rate of 5° C./min.

(28) <Preparation of Semiconductor Package>

(29) A TO247 type package was prepared by insert molding of a copper lead frame using a low pressure transfer molding machine. The molding conditions were set as follows: a mold temperature of 180° C., a clamping pressure of 294 kN, a preheating time of 5 seconds, an injection pressure of 15 kN, an injection rate of 0.9 mm/s, a transfer time of 18 seconds, and a curing time of 300 seconds.

(30) In Examples 1 to 4 where the evaluation conditions of the post-curing and the heat cycle test in reliability evaluation described below were made severer to increase thermal stress generated in the package, a 1.5 mm □ SiC Schottky barrier diode was die-bonded on a pad using a high temperature lead solder, and the diode element and a terminal were wire-bonded to each other using a 350 μm diameter aluminum wire.

(31) <Reliability Evaluation>

(32) In order to examine the influence of the residual internal stress on the inner structure of the package when the degree of cure of the sealing material was increased by post-curing, the package was left in an inert oven at 250° C. under nitrogen flow for 5 hours.

(33) Moreover, a heat cycle test was performed to examine the influence on the inner structure of the package caused by the internal stress generated when the package was repeatedly exposed to cold and hot environments. The conditions of the heat cycle test were as follows: the lower limit for cooling mode was set at −50° C. for 30 minutes; the upper limit for heating mode was set at +225° C. for 30 minutes; and the cooling/heating time was about 3 minutes.

(34) The inner structure of the package was determined using an ultrasonic tester (FineSAT III, from Hitachi Power Solutions Co., Ltd.), and rated “bad” if separation was observed at the interface between the integrated components in the package and the sealing material; “fair” if no separation was observed but many non-uniform structures such as voids or gels were observed; and “excellent” if no separation and only a small number of non-uniform structures were observed.

(35) The results of the reliability evaluation were shown in Table 1, and the results of the ultrasonic test were shown in FIGS. 1-1 to 2-2. In FIGS. 1-1 and 1-2, the portions with a color indicated by A mean that separation occurred at the interface between the integrated components in the package and the sealing material so that a void was formed, while the portions with a color indicated by B mean that a void larger than in the portions with a color indicated by A was formed.

(36) TABLE-US-00001 TABLE 1 Comparative Comparative Example 1 Example 1 Example 2 Example 2 Example 3 Example 4 Formulation Cyanate ester 19.14 19.43 9.84 9.99 8.41 3.71 of resin (g) compound Carbodiimide 0.29 0 0.29 0 0.15 0.15 compound Maleimide 0 0 9.30 9.44 4.63 8.20 compound Siloxane 0 0 0 0 6.24 0 compound 1 Siloxane 0 0 0 0 0 7 compound 2 Co(acac).sub.2 0.16 0.16 0.16 0.16 0.16 0.16 t-Butylphenol 0.33 0.33 0.33 0.33 0.33 0.33 Carbon black 0.34 0.34 0.34 0.34 0.34 0.34 Carnauba wax 0.35 0.35 0.35 0.35 0.35 0.35 Silane coupling 0.24 0.24 0.24 0.24 0.24 0.24 agent Silica 69.65 69.65 69.65 69.65 69.65 69.65 Magnesium 7.00 7.00 7.00 7.00 7.00 7.00 hydroxide Silicone oil 2.50 2.50 2.50 2.50 2.50 2.50 Evaluation of Evaluation of Bad Bad Good Good Excellent Excellent encapsulant handleability properties Tg (DMA, ° C.) 320 320 335 335 400 or higher 400 or higher Reliability Immediately Excellent Fair Excellent Fair Excellent Excellent evaluation after molding (conditions inside After post-curing Excellent Bad Excellent Bad Excellent Excellent semiconductor After heat cycle Excellent — Excellent — Excellent Excellent package) test (500 cycles)

(37) The cyanate ester compound, the maleimide compound, the carbodiimide compound, and the silane coupling agent shown in Table 1 are as follows.

(38) Cyanate ester compound: A phenol novolac-type cyanate ester compound represented by formula (12) below (Primaset PT30, from Lonza Japan)

(39) Maleimide compound: A bismaleimide compound having a structure represented by formula (13) below (bismaleimide BMI80, from K.I Chemical Industry Co., Ltd.)

(40) Carbodiimide compound: An aliphatic polycarbodiimide compound (product name “CARBODILITE V-05”, from Nisshinbo Chemical Inc.)

(41) Silane coupling agent: N-phenyl-3-aminopropyltrimethoxysilane (product name “KBM573”, from Shin-Etsu Chemical Co., Ltd.)

(42) ##STR00017##

REFERENCE SIGNS LIST

(43) A: the portion where a void is formed B: the portion where a void larger than in the portion A is formed