JP3496242B2 - Epoxy resin molding compound for sealing electronic components - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin molding material having excellent reflow crack resistance, which is useful as a molding material for sealing electronic parts, particularly plastic packaging ICs for surface mounting.

[0002]

2. Description of the Related Art Conventionally, molding materials for encapsulating electronic parts such as transistors and ICs have been characterized by electrical characteristics, moisture resistance, heat resistance,
Epoxy resin molding materials with excellent mechanical properties and adhesiveness with inserts are used. In particular, since a high heat resistance is required for a molding material for IC encapsulation, an epoxy resin molding material in which an o-cresol novolac type epoxy resin which is a polyfunctional epoxy resin is cured by a phenol novolac resin which is a polyhydric phenol compound is widely used. Has been.

With the recent trend toward high-density mounting of printed wiring boards, surface mounting types have become the mainstream of electronic component packages rather than the conventional bin insertion type. Surface mount IC
In order to increase the density and lower the mounting height, the package is becoming smaller and thinner year by year, the volume occupied by the elements in the package is relatively large, and the thickness of the package is very thin. There is.

Further, in the conventional pin insertion type package, since the soldering is performed from the back surface of the wiring board after it is inserted into the wiring board, the package is not directly exposed to high temperature. After being stopped, it is processed in a solder bath, a solder reflow device or the like, so that the package is directly exposed to a high soldering temperature. As a result, in the surface mount type, if the IC package absorbs moisture, a defect that the absorbed moisture abruptly expands during soldering to cause a crack in the package occurs, which is a major problem of the surface mount type IC. It has become.

Up to now, in order to prevent package cracks during solder reflow, ICs are protected by moisture-proof packaging,
Although a method has been proposed in which the IC is sufficiently dried before being mounted on a wiring board, all of them have a problem that the cost is increased, and the surface mounting type has low moisture absorption and good crack resistance. Development of an epoxy resin molding material for IC encapsulation has been demanded.

In order to meet this demand, many proposals have been made to improve the hygroscopicity and crack resistance of the epoxy resin molding material for encapsulating electronic parts. That is, an epoxy resin molding material containing a highly water-absorbent resin (JP-A-62-1)
No. 00522), those using fluorine-containing phenols (see JP-A-1-118524), those using highly-alkylated epoxy resin and novolac resin (see JP-A-3-128918), specific Three
Using functional phenolic resin (Japanese Patent Application Laid-Open No. 3-2436)
No. 16), and those using a highly hydrophobic curing agent such as cyclopentadienyl-modified novolac resin (see JP-A-4-139210). Further, those using a naphthalene-modified epoxy resin and novolac resin (see JP-A-3-43412), those using an epoxy resin made from a naphthol-type polymer as a raw material (see JP-A-4-337314), and bisnaphthylmethane. Type polyfunctional epoxy resin (Japanese Patent Laid-Open No. 4-3373)
No. 16), a resin composition having a naphthalene structure introduced into the resin skeleton is also proposed.

[0007]

However, when a highly water-absorbent resin is blended with an epoxy resin molding material as disclosed in JP-A-62-100522, the heat resistance of the epoxy resin molding material is lowered. There is a problem. Further, those using a highly alkylated epoxy resin or novolac resin described in JP-A-3-128918, those using fluorine-containing phenols disclosed in JP-A-1-118524, -24
Those using a specific trifunctional phenol resin disclosed in Japanese Patent No. 3616 and those using a cyclopentadienyl-modified novolac resin disclosed in JP-A-4-139210 as a curing agent are epoxy resins. Although the hygroscopicity of the package is slightly improved by making it hydrophobic, it was insufficient to prevent cracks during solder reflow.

Further, JP-A-3-43412, JP-A-4-337316 and JP-A-4-337316.
Even in the case where a naphthalene structure is introduced into the resin skeleton of the composition as disclosed in Japanese Patent Laid-Open Publication No. 2003-242242, it was insufficient to prevent cracks during solder reflow. The present invention is
Provided is an epoxy resin molding material for encapsulating an electronic component, which improves the hygroscopicity of an IC package without impairing the heat resistance of a conventional epoxy resin molding material and causes no cracks during solder reflow.

[0009]

Means for Solving the Problems As a result of intensive studies for solving the above-mentioned problems, the present inventors have obtained it when a phenolic compound in which a phenolic hydroxyl group is aryl esterified is used as a curing agent for an epoxy resin. The inventors have found that the resin cured product has a remarkably low water absorption, and have reached the present invention.

The present invention provides an epoxy resin having two or more epoxy groups in the molecule, a polyhydric phenol compound in which a phenolic hydroxyl group is aryl esterified (hereinafter simply referred to as an aryl esterified phenol compound) and an inorganic filler. It is an epoxy resin molding material for electronic component encapsulation, which is an essential component.

A feature of the present invention is that the aryl esterified phenol compound is used as a curing agent for the epoxy resin. The aryl esterified phenol compound can be obtained by reacting a polyhydric phenol compound with benzoyl chloride or alkyl-substituted benzoyl chloride.

Specific examples of the aryl esterified phenol compound include bisbenzoylated bisphenol A, bisalkylbenzoylated bisphenol A, bisbenzoylated tetrabromobisphenol A, bisalkylbenzoylated tetrabromobisphenol A, and benzoylated phenol novolak. Examples thereof include resins, alkylbenzoylated phenol novolac resins, benzoylated cresol novolac resins, and alkylbenzoylated cresol novolac resins, which may be used alone or as a mixture.

Along with aryl esterified phenolic compounds, phenolic hardeners such as phenol novolac, which have been conventionally used as a hardener for epoxy resins, amine hardeners such as diethylenetriamine and diaminodiphenylmethane, and tetrahydroanhydrophthalic anhydride, if necessary. An acid anhydride-based curing agent such as an acid, a guanidine-based curing agent such as dicyandiamide, or a guanamine-based curing agent such as benzoguanamine can be used. From this meaning, when polyhydric phenols are esterified, as shown in Chemical formula 1, all of the phenolic hydroxyl groups may be left without being esterified, and polyhydric phenol compounds that are not esterified remain. May be. If only a polyhydric phenol compound in which all phenolic hydroxyl groups are esterified is used as a curing agent, the adhesive force will decrease, so it is preferable to leave some of the phenolic hydroxyl groups or use another curing agent in combination. However, in order to suppress the water absorption of the resin to a low level, it is desirable that the amount of the curing agent other than the aryl esterified phenol compound is 50 parts by weight or less based on 100 parts by weight of the epoxy resin.

[0014]

[Chemical 1]

The amount of the aryl esterified phenol compound to be compounded depends on the content of the arylate group and the content of the phenolic hydroxyl group remaining without being esterified. That is, it is considered that the aryl esterified phenol compound reacts with the epoxy group of the epoxy resin in both the arylate group and the residual phenolic hydroxyl group, and the equivalent derived from the contents of both corresponds to the equivalent as the curing agent. Therefore, the compounding amount of the aryl esterified phenol compound is preferably 0.8 to 1.2 equivalent ratio to the epoxy equivalent of the epoxy resin, as in the case of the non-esterified polyhydric phenol compound.
It is desirable to mix the aryl esterified phenol compound in the range of 50 to 200 parts by weight with respect to 100 parts by weight of the epoxy resin. Even when the amount of the aryl esterified phenol compound is 50 parts by weight or less, or 200 parts by weight or more, it is difficult to obtain a cured product having sufficient strength and heat resistance.

The epoxy resin used in the epoxy resin molding material of the present invention is a compound having two or more epoxy groups in the molecule, and the epoxy resin generally used for sealing electronic parts can be used as it is. Specific examples of the epoxy resin used in the epoxy resin molding material of the present invention include phenol novolac type epoxy resin, cresol novolac type epoxy resin, biphenyl type epoxy resin, naphthol modified novolac type epoxy resin, bisphenol A type epoxy resin, bromine. Bisphenol A type epoxy resin, brominated phenol novolac type epoxy resin, glycidyl amine type epoxy resin using polyamine such as diaminodiphenylmethane and isocyanuric acid as raw materials, and a mixture thereof.
To obtain good heat resistance as a resin for encapsulating electronic parts, a phenol novolac type epoxy resin having an epoxy equivalent of 230 or less or a cresol novolac type epoxy resin is preferable.

Regarding the purity of the epoxy resin used in the epoxy resin molding material of the present invention, it is better that the amount of hydrolyzable chlorine which causes corrosion of aluminum wiring on an element such as an IC is smaller, and an electronic component having good moisture resistance. In order to obtain the epoxy resin molding material for sealing, it is preferably 500 ppm or less, but it is not particularly limited.

In the epoxy resin molding material for encapsulating electronic parts of the present invention, an inorganic filler is used to reduce hygroscopicity and improve strength. As the inorganic filler, crystalline silica, fused silica, alumina, zircon, calcium silicate, calcium carbonate, silicon carbide, silicon nitride, boron nitride, magnesia, zirconia, zircon, etc. are powdered or spherical beads are used. And the like, and one kind or a mixture of plural kinds is used. The blending amount of the filler is required to be 55% by volume or more in order to reduce hygroscopicity and improve strength, and preferably 60% by volume or more.

In the epoxy resin molding material of the present invention, a curing accelerator is used in order to accelerate the curing reaction between the aryl esterified phenol compound and the epoxy resin and reduce the water absorption of the resin. Most of the curing accelerators conventionally used in the curing reaction between the epoxy resin and various curing agents also accelerate the curing reaction between the aryl esterified phenol compound of the epoxy resin molding material of the present invention and the epoxy resin. It is confirmed to do. Specific examples of such a curing accelerator include basic catalysts such as 1,8-diaza-bicyclo (5,4,0) undecene-7, triethylenediamine, dimethylbenzylamine and tris (dimethylaminomethyl) phenol. Tert-amines, 2-methylimidazole, 2-phenylimidazole, imidazole such as 2-phenyl-4-methylimidazole and derivatives thereof, organic phosphines such as tributylphosphine, methyldiphenylphosphine and triphenylphosphine, tetraphenylphosphonium tetra Phenylborate, 2-ethyl-4-methylimidazole tetraphenylborate, N-methylmorpholine tetraphenylborate, tetraphenylphosphonium ethyltriphenylborate, tetrabutylphosphonium tetrab Tetraphenyl boron salts and phosphonium boron salts such as Ruboreto the like.

The compounding amount of the curing accelerator is 0.1 to 1.0 part by weight based on 100 parts by weight of the total weight of the aryl esterified phenol compound, the epoxy resin and the other curing agent.

As other additives, liquid or solid silicone compounds, flexibilizers such as telechelic rubber and thermoplastic elastomers, release agents such as higher fatty acids, higher fatty acid metal salts and ester waxes, carbon Colorants such as black, coupling agents such as epoxysilane, aminosilane, ureidosilane, vinylsilane, alkylsilane, organic titanate, and flame retardants can be used.

As a general method for producing the epoxy resin molding material for encapsulating electronic parts of the present invention using the above raw materials, after thoroughly mixing a predetermined amount of the raw materials with a mixer or the like, Examples thereof include a method in which a molding material is obtained by kneading with a mixing roll or an extruder, cooling and pulverizing.

As a method for sealing electronic parts using the epoxy resin molding material of the present invention, the low pressure transfer molding method is the most general method, but the injection molding method or the compression molding method is also possible.

[0024]

[Function] In the case of a usual reaction between a polyhydric phenol compound and an epoxy resin, a hydrophilic hydroxyl group is produced as a by-product of the ring opening of the epoxy group, but when the aryl esterified phenol compound reacts with the epoxy resin. In addition, it is considered that the acyl group of the aryl esterified phenol compound reacts with the hydroxyl group together with the ring opening of the epoxy group to form an ester having low hydrophilicity. That is, the reason why the water absorption property of the epoxy resin cured product is improved by using an aryl esterified phenol compound as a curing agent is that unlike a usual curing reaction between an epoxy resin and a polyhydric phenol, it does not generate a hydroxyl group. It is presumed that this is to suppress the hydrophilicity of the cured resin.

[0025]

EXAMPLES The present invention will be specifically described below with reference to specific examples, but the present invention is not limited thereto.

Example 1 5 L of 4 equipped with a thermometer, a cooling pipe, a nitrogen introducing pipe, and a stirring rod
228 g of bisphenol A was added to a one-necked flask, 1 L of tetrahydrofuran was added, and the mixture was stirred and dissolved under a nitrogen stream, 240 g of triethylamine was added, and the internal temperature was cooled to 10 ° C. with an ice bath. Next, 310 g of benzoyl chloride, being careful not to let the internal temperature exceed 10 ° C.
Was added dropwise over 2 hours, and after completion of the addition, the mixture was further stirred at room temperature for 2 hours. Then, the precipitate was separated by filtration, triethylamine hydrochloride was washed off with a large amount of distilled water, and dried at 100 ° C. for 6 hours under reduced pressure.

¹³ C-NMR spectrum (model: AC300P manufactured by Bruker, solvent: CD) of the obtained product
Cl ₃ , concentration: 10%) was investigated. As a result, the signal of carbon bonded to the hydroxyl group existing in the raw material bisphenol A was detected in a high magnetic field (152 ppm to 149 ppm).
, A signal (165 ppm) appeared at the carbonyl carbon of a new ester, and it was confirmed that the product was the target bisbenzoylated bisphenol A. The obtained bisbenzoylated bisphenol A (hereinafter referred to as BBP) was 375 g.

Epoxy equivalent 200 g of cresol novolac type epoxy resin (ESCN manufactured by Sumitomo Chemical Co., Ltd.
195) 80 parts (parts by weight, the same applies hereinafter), epoxy equivalent 285 g of brominated phenol novolac type epoxy resin (using BREN-S manufactured by Nippon Kayaku Co., Ltd.) 20
Part, BBP 110 parts, 1,8-diazabicyclo (5,
4,0) Undecene-7 (1.5 parts), carnauba wax (2 parts), carbon black (1 part), γ-glycidoxypropyltrimethoxysilane (2 parts) and quartz glass powder (55% by volume) were mixed, and the diameter was 254 mm (10 inches). Kneading was performed under the conditions of a temperature of 80 to 90 ° C. and a time of 7 to 10 minutes using the heating roll of No. 1 to prepare an epoxy resin molding material.

Example 2 5 L of 4 equipped with a thermometer, a cooling tube, a nitrogen introducing tube and a stirring bar
212 g of phenol novolac resin (using HP-850N of Hitachi Chemical Co., Ltd.) was put into a one-necked flask, 1 L of methyl ethyl ketone was added and dissolved by stirring under a nitrogen stream, and 240 g of triethylamine was added, followed by addition with an ice bath. It was cooled to a temperature of 10 ° C. Be careful not to let the internal temperature exceed 10 ° C, and add 2 g of 310 g of benzoyl chloride.
The mixture was added dropwise over a period of time, and after completion of the addition, the mixture was further stirred at room temperature for 2 hours. Then, triethylamine hydrochloride was removed by suction filtration, and the filtrate was concentrated under reduced pressure to obtain 380 g of a crude product. The obtained crude product was dissolved in 3 L of toluene, washed thoroughly with distilled water, charged with anhydrous magnesium sulfate and allowed to stand overnight, filtered, and the solution was concentrated under reduced pressure.
It was dried under reduced pressure at 6 ° C for 6 hours.

¹³ C-NMR spectrum (model: AC300P manufactured by Bruker, solvent: CD) of the obtained product
Cl ₃ , concentration: 10%) was investigated. As a result, the signal of carbon which was bonded to the hydroxyl group, which was present in the raw material phenol novolac resin, was detected at a high magnetic field (from 152 ppm to 14 ppm).
9 ppm), and a signal (165 ppm) appeared on the carbonyl carbon of the new ester, confirming that the product was the desired benzoylated phenol novolac resin. The obtained benzoylated phenol novolac resin (hereinafter referred to as BPN-1)
Was 350 g.

Next, 80 parts of ESCN195 and brominated bisphenol A type epoxy resin having an epoxy equivalent of 395 g (using ESB-400 manufactured by Sumitomo Chemical Co., Ltd.) 20
Part and BPN-1 95 parts, an epoxy resin molding material was prepared in the same manner as in Example 1.

Example 3 The synthesis reaction was performed in the same manner as in Example 2 except that the amount of triethylamine was changed to 120 g and the amount of benzoyl chloride was changed to 145 g, and the phenolic hydroxyl group was 50%.
270 g of an aryl esterified phenol novolac resin (hereinafter referred to as BPN-2) was obtained.

Next, in place of 95 parts of BPN-1, BP
An epoxy resin molding material was produced in the same manner as in Example 2 except that N-2 was 75 parts.

Example 4 240 g of o-cresol novolac resin having a number average molecular weight of 1010 was used in place of HP-850N in Example 2.
Then, a synthetic reaction is performed in the same manner as in Example 2 to obtain a benzoylated-o-cresol novolac resin (B
380 g was obtained.

Next, biphenyl type epoxy resin (YX-4000H manufactured by Yuka Shell Epoxy Co., Ltd. is used) 80
Part, 20 parts of BREN-S, 115 parts of BCN, and 65% by volume of quartz glass powder were mixed to prepare an epoxy resin molding material in the same manner as in Example 1.

Example 5 A synthetic reaction was performed in the same manner as in Example 2 except that tolylcarbonyl chloride was used instead of benzoyl chloride to obtain an alkyl-substituted aryl esterified phenol novolac resin (hereinafter referred to as TPN) 360.

Next, 80 parts of YX-4000H, ESB
An epoxy resin molding material was produced in the same manner as in Example 1 except that 20 parts of -400, 105 parts of TPN and 65 vol% of quartz glass powder were blended.

Comparative Example BPN-1 was replaced with HP-850N110 parts to prepare an epoxy resin molding material in the same manner as in Example 2.

The characteristics of the obtained epoxy resin molding material are
It evaluated by the method shown below. Spiral flow: measured using a mold conforming to EMMI 1-66 under the conditions of 180 ° C., 90 seconds and 6.9 MPa. Glass transition temperature (Tg): A linear expansion curve was obtained with a thermomechanical analyzer (TMA) manufactured by Rigaku Denki Co., Ltd., and the linear expansion curve was obtained from the bending point. High temperature strength: Measured at 215 ° C. by a three-point support type bending test method based on JIS K6911. Water absorption rate: Diameter of 50m according to JIS K6911
A disc having a thickness of 3 mm and a thickness of 3 mm was prepared, humidified under the conditions of 85 ° C. and 85% RH, and the weight change was obtained.

Table 1 shows the results of these measurements. From Table 1, the molding material according to the present invention (Example) exhibits the same fluidity (spiral flow) and heat resistance (glass transition temperature, high temperature strength) as the conventional molding material (Comparative Example), and the water absorption rate is It can be seen that it is significantly lower than the molding material of the comparative example.

[0041]

[Table 1] ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ A B C a b c ──── ──────────────────────────────── Example 1 50 140 12 0.11 0.14 0.18 Example 2 43 150 12 0.11 0.13 0.17 Example 3 42 150 12 0.14 0.17 0.22 Example 4 41 145 12 0.10 0.12 0.16 Example 5 42 140 12 0. 10 0.12 0.15 Comparative example 40 150 12 0.18 0.22 0.30 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ━━━━━━━ Note) A: Spiral flow (in), B: Glass transition temperature
(° C), C: High temperature strength (MPa) a to c: Water absorption rate (%) (a:
(48 hours, b: 72 hours, c: 168 hours)

Further, the IC package was molded under the conditions of 180 ° C., 90 seconds, and 7 MPa, post-curing was performed at 180 ° C. for 5 hours after molding, and crack resistance during solder reflow and after solder reflow were performed by the following method. Was examined for heat resistance. Crack resistance: A flat package (outer dimensions; 19 × 14 × 2.0 mm) of 80-pin, 42-lead having an element of 8 × 10 × 0.4 mm mounted was used as an IC for evaluation, and this package was 85 ° C. After humidifying at 85% RH for a predetermined time, it is heated in a vapor phase reflow furnace at 215 ° C for 9 hours.
After heating for 0 second, the presence or absence of package cracking was judged by microscopic observation. Moisture resistance after solder reflow: 5x10x0.4mm test element with aluminum wiring of 10μm width mounted, 2
350mil wire-bonded with 5μm gold wire,
A 28-pin outline package was used as an IC for evaluation, the package was humidified at 85 ° C. and 85% RH for 72 hours, heated in a vapor phase reflow furnace at 215 ° C. for 90 seconds, and then 0.2 MPa, 121 ° C., 100 ° C. % R
Humidification was performed for a predetermined time under the condition of H, and the occurrence of disconnection failure due to aluminum wiring corrosion was examined.

Table 2 shows the results of these tests. It can be seen from Table 2 that the molding materials according to the present invention (Examples) have significantly improved crack resistance during solder reflow and moisture resistance after solder reflow, as compared with conventional molding materials (Comparative Examples). I understand.

[0044]

[Table 2] ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━           Crack resistance during reflow Moisture resistance after reflow           18h 24h 36h 48h 100h 200h 400h 600h 800h 1000h ──────────────────────────────────── Example 1 0/5 0/5 0/5 1/5 0/14 0/14 0/14 0/14 0/14 0/14 Example 2 0/5 0/5 0/5 0/5 0/14 0/14 0/14 0/14 0/14 0/14 Example 3 0/5 0/5 0/5 1/5 0/14 0/14 0/14 0/14 0/14 0/14 Example 4 0/5 0/5 0/5 0/5 0/14 0/14 0/14 0/14 0/14 0/14 Example 5 0/5 0/5 0/5 0/5 0/14 0/14 0/14 0/14 0/14 0/14 Comparative Example 0/5 1/5 3/5 5/5 0/14 0/14 0/14 3/14 6/14 7/14 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Note) Crack resistance during reflow: 85 ℃, humidified at 85% RH, the time shown in the table Displays (number of defects / number of tests) after holding     Moisture resistance after reflow: PCT (0.2 MPa, 121 ° C, 100% RH) Displays (number of defects / number of tests) after holding for the time shown in the table

[0045]

EFFECT OF THE INVENTION The epoxy resin molding material for encapsulating electronic parts of the present invention has lower water absorption than conventional molding materials, good crack resistance during solder reflow and good moisture resistance after solder reflow. Mounting plastic package I
It is suitable as a C molding material.

Continuation of the front page (56) Reference JP 61-212544 (JP, A) JP 7-25962 (JP, A) JP 7-82348 (JP, A) JP 6-107724 (JP , A) JP 4-226122 (JP, A) JP 4-29986 (JP, A) JP 62-1722 (JP, A) JP 59-215314 (JP, A) JP 54-155298 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08G 59/00-59/72 C08L 63/00-63/10 H01L 23/29 H01L 23/31

Claims (6)

(57) [Claims] 1. An epoxy resin having two or more epoxy groups in a molecule, a polyhydric phenol compound obtained by arylesterifying a phenolic hydroxyl group (provided that an amino group or an acid is used).
Excluding those having an anhydride group. ) And an epoxy resin molding material for encapsulating electronic parts, which contains an inorganic filler as an essential component. 2. An aryl ester having a phenolic hydroxyl group.
The polyhydric phenol compounds converted to phenolic hydroxyl groups
Phenyl or alkyl substituted phenyl ester polyvalent
The electronic component encapsulation according to claim 1, which is a phenol compound.
Epoxy resin molding material. Wherein the polyhydric phenol compound, electronic parts encapsulating epoxy resin molding material according to claim 1 or 2 wherein the bisphenol A. Wherein the polyhydric phenol compound, electronic parts encapsulating epoxy resin molding material according to claim 1 or 2, wherein the phenolic novolak resin. 5. The epoxy resin molding material for electronic component encapsulation according to claim 4 , wherein the phenolic novolac resin is a cresol novolac resin. 6. The epoxy resin having two or more epoxy groups in the molecule is a phenol novolac type epoxy resin, a cresol novolac type epoxy resin, a biphenyl type epoxy resin, a brominated bisphenol A type epoxy resin or a brominated phenol novolac type resin. The epoxy resin molding material for encapsulating electronic parts according to claim 1, 2 , 3 , 4, or 5, which is a single epoxy resin or a mixture of two or more epoxy resins selected from epoxy resins.