KR100585945B1 - Epoxy Resin Composition for Encapsulation of Semiconductor Device - Google Patents

Abstract

The present invention relates to a semiconductor element sealing type epoxy resin composition, and more particularly, 1) a mixture of a cresol noblock epoxy resin and a glycidyl ether bisphenol-modified epoxy resin of a specific structure; 2) difunctional or polyfunctional phenol resins and phenol noblock resins as curing agents; 3) alkyl alkoxy silanes containing epoxy groups at the terminals and alkyl alkoxy silanes containing imidazole groups at the terminals as coupling agents; 4) latent curing catalysts; 5) cocatalyst of the latent curing catalyst; 6) flame retardants; And 7) relates to an epoxy resin composition for sealing semiconductor elements comprising an inorganic filler. By using the epoxy resin composition according to the present invention, it is possible to improve the peeling problem that occurs between the wafer chip surface and the epoxy encapsulant in the semiconductor device encapsulation process, and has excellent mechanical properties, insulation properties and hygroscopic properties, and a solder temperature of 265 ° C. Even when applied to the Pb free solder process, cracks hardly occur on the pad surface and the chip, and high reliability of the manufactured device can be guaranteed.

Description

Epoxy Resin Composition for Encapsulation of Semiconductor Device

The present invention relates to a semiconductor element sealing type epoxy resin composition, and more particularly, 1) as an epoxy resin cresol noblock epoxy resin and glycidyl ether bisphenol-modified epoxy resin of a specific structure; 2) difunctional or polyfunctional phenol resins and phenol noblock resins as curing agents; 3) alkyl alkoxy silanes containing epoxy groups at the terminals and alkyl alkoxy silanes containing imidazole groups at the terminals as coupling agents; 4) latent curing catalysts; 5) cocatalyst of the latent curing catalyst; 6) flame retardants; And, 7) relates to an epoxy resin composition for sealing semiconductor elements containing an inorganic filler.

Recently, due to the trend toward higher integration of semiconductor devices, the size of devices, the size of cells are reduced, and the multilayers of wirings are rapidly progressing, and packages that protect semiconductor devices from the external environment are also mounted on the printed circuit boards (that is, , Surface mounting) is accelerating compactness and thinning. On the other hand, due to strict environmental regulations and the known harmful health of lead (Pb) and tin (Sn), the use of lead in the solder process, which is a post-process, is prohibited. Is active.

Currently known solder materials that can be used in place of lead, such as tin (Sn), bismuth (Bi), silver (Ag), etc., when using the alternative material, the temperature of the solder is 265 at the existing 230 ℃ It should be raised to ℃. Therefore, when a device using a conventional epoxy resin composition for semiconductor element sealing is put into a lead-free solder process, it is difficult to obtain a reliable product due to severe package cracks due to high temperature and the interface peeling between the wafer and the epoxy resin composition. In addition, when the resin-sealed semiconductor, in which a large semiconductor device is sealed in a small and thin package, is applied to a Pb free solder process, the crack problem in the package is further increased due to thermal stress caused by temperature and humidity changes in the external environment. At the same time, the incidence of aluminum pad corrosion increases. Accordingly, research for improving the crack resistance and low stress of the epoxy resin composition for sealing semiconductor devices is in progress.

In the conventional epoxy resin encapsulant, a method of lowering the hygroscopicity of the encapsulant and increasing the adhesive strength and the high temperature strength is known in order to increase the crack resistance, and in order to increase the reliability of the encapsulant material, the amount of filler for lowering the stress is increased. The method of adjusting, reducing a thermal expansion coefficient, or making low elasticity by adding a modifier is known. In other words, in order to lower the thermal stress of the package, a high filling technology (high loading according to a combination of fillers) according to a low stress is known, and a modification of the resin composition by various rubber components is required for low elasticity (Japanese Patent Application Laid-Open No. 63-1894). And Japanese Patent Application Laid-Open No. Hei 5-291436, an epoxy resin molding material blended and modified with a silicone polymer having excellent thermal stability has been widely adopted. According to the above method, since the silicone oil is incompatible with the epoxy resin and the curing agent, which are the base resins of the molding material, it is in the form of fine particle dispersion (sea island structure) in the base resin, and thus a low elastic modulus can be achieved while maintaining the heat resistance. However, when the composition according to the above technique is applied to a lead-free solder process in which the temperature of the solder must be raised to 265 ° C, package cracks are generated due to a decrease in adhesion between the epoxy encapsulant and the lead-on chip and the epoxy encapsulant and an increase in water vapor pressure. It is difficult to obtain this high semiconductor element.

Therefore, there is a need in the art for an epoxy resin composition for sealing semiconductor devices that can hardly generate cracks and ensure high reliability of the device even when applied to a high temperature lead-free solder process.

The present inventors have diligently studied to solve the above problems, and as an epoxy resin, a modified diglycidyl ether bisphenol epoxy resin is used in combination with an ortho cresol noblock resin, and a bifunctional or polyfunctional phenol noblock resin as a curing agent. When the epoxy resin composition prepared by using a mixture of a phenolic resin and a mixture of an alkyl alkoxy silane having an epoxy group at the terminal and an alkyl alkoxy silane having an imidazole group at the terminal as a coupling agent is applied to the semiconductor sealing, The problem of peeling between the wafer chip surface and the epoxy encapsulant can be improved, and no crack is generated on the pad surface and the chip even when applied to a lead-free solder process with a solder temperature of 265 ° C or higher, and the manufactured device maintains high reliability. It was confirmed that the present invention, and it came to the present invention.

In conclusion, the present invention is excellent in the adhesive properties to the surface of the substrate and the mechanical properties of the resin after curing, the crack generation is significantly reduced even in the high temperature solder process can be advantageously applied to the lead-free solder process, the high An object of the present invention is to provide an epoxy resin composition for sealing semiconductor elements which is reliable.

One aspect of the present invention for achieving the above object is 1) a cresol noblel epoxy resin and a glycidyl ether bisphenol-modified epoxy resin of a specific structure as an epoxy resin; 2) difunctional or polyfunctional phenolic resins and phenol noblock resins as curing agents; 3) alkyl alkoxy silanes containing epoxy groups at the terminals and alkyl alkoxy silanes containing imidazole groups at the terminals as coupling agents; 4) latent curing catalysts; 5) cocatalyst of the latent curing catalyst; 6) flame retardants; And 7) relates to an epoxy resin composition for sealing semiconductor elements comprising an inorganic filler.

Hereinafter, the present invention will be described in more detail.

The epoxy resin composition according to the present invention comprises a glycidyl ether bisphenol-modified epoxy resin of the following general formula (1) in addition to the cresol noblock epoxy resin as an epoxy resin:

(Wherein R is a hydrogen atom or a methyl group, G is a glycidyl group, n is an integer from 0 to 3),

According to the research of the present inventors, since the bisphenol-modified epoxy resin has at least two oxirane rings in one molecule, while maintaining a high elastic modulus compared to the conventional resin composition in the structure, it is possible to increase the low shrinkage rate and increase in the occurrence of cracks It can solve the problem effectively. The bisphenol-modified epoxy resin, for example, can be prepared by reacting a diglycidyl ether bisphenol epoxy resin of the formula (2) with a compound containing an oxirane group, such as epichlorohydrin, preferably an epoxy equivalent of 200 to It is 360 high purity epoxy resin:

(Wherein R is a hydrogen atom or a methyl group, G is a glycidyl group and n is an integer of 0 to 3).

The mixing ratio (by weight) of the cresol noblac epoxy resin and the diglycidyl ether bisphenol-modified epoxy resin used as the epoxy resin in the epoxy resin composition according to the present invention is 80:20 to 20:80. Mixed epoxy resins are present in amounts of from 5 to 16% by weight, based on the weight of the total composition.

The epoxy resin composition according to the present invention comprises 2) a polyfunctional phenol resin of formula 3 and a phenol noblock resin of formula 4 as a curing agent:

(Wherein n is an integer of 0 to 4); And

(Where n is an integer of 0 to 4).

The polyfunctional phenolic resin is used in an amount of 2 to 4% by weight based on the weight of the total composition, and the phenol noblock resin is used in an amount of 2 to 5% by weight.

The epoxy resin composition according to the present invention contains an alkyl alkoxy silane containing an epoxy group at the terminal and an alkyl alkoxy silane containing an imidazole group at the terminal as a coupling agent. Preferably, γ-glycithoxy propylene methoxy silane, γ-glycithoxy propylene ethoxy silane, γ-glycithoxy butylenemethoxy silane, β- (3,4 epoxy) as alkyl alkoxy silanes containing an epoxy group at the terminal Cyclohexyl) ethylenemethoxy silane or mixtures thereof may be used, and alkylalkoxy silanes in which the end group is substituted with imidazole are used alone or in combination with a compound of formula (5):

(Wherein R ¹ , R ² , R ³ , and R ⁴ are each independently of each other hydrogen or an alkyl group having 1 to 6 carbon atoms, n is an integer of 1 to 3).

In combination with the diglycidyl ether bisphenol-modified epoxy resin of component 1), when the above two or more coupling agent mixtures are used, the adhesion properties between the wafer chip surface and the encapsulation material are greatly improved, and package cracks do not occur even at high solder temperatures. In addition, the reliability of the manufactured device is increased. The use ratio of the coupling agent mixture is 5 to 60 parts by weight of imidazole-based alkyl alkoxy silane based on 100 parts by weight of alkyl alkoxy silane including epoxy group at the terminal, and the amount of the imidazole alkyl alkoxy silane is less than 5 parts by weight. In this case, there is no effect of improving peeling between chips, and when it is more than 60 parts by weight, it may cause a degate burr problem in operation. A coupling agent substituted with a multo-to or amine group can be used in combination within the range of not impairing the object of the present invention. 3) The content of the coupling agent in the epoxy resin composition according to the present invention is 0.2 to 2.0% by weight based on the total weight of the composition.

The epoxy resin composition according to the present invention uses 4) a latent curing catalyst to control the curing rate. 4) Examples of compounds that can be used as latent curing catalysts include isocyanate-based latent curing catalysts such as isocytimidazole, tetraphenylphosphonium tetraphenylborate, triphenylphosphinetetraphenylborate, and tetraphenylboron salts. do. 4) The content of the latent curing catalyst is 0.05 to 0.40% by weight based on the weight of the entire resin composition.

When the latent curing catalyst is used alone, it is difficult to obtain desired curing characteristics, so the epoxy resin composition according to the present invention uses 5) curing cocatalysts together. Examples of cocatalysts that can be used are amine compounds or phos such as benzyldimethylamine, triethanolamine, triethylenediamine, dimethylaminoethanol, tri (dimethylaminomethyl) phenol, triphenylphosphine, diphenylphosphine, phenylphosphine It is a fin organic compound. The compounds may be used alone or in combination of two or more. 5) The amount of the curing cocatalyst is 0.01 to 0.2% by weight based on the total weight of the composition.

The epoxy resin composition according to the present invention may include a flame retardant 6) to have flame retardancy. 6) As a flame retardant, polyglycidyl ether brominated phenol epoxy resin having an epoxy equivalent weight of 250 to 400 and a bromine content of 35 to 50% by weight based on the flame retardant epoxy is mixed with antimony trioxide. 6) The flame retardant is used in an amount of 0.1 to 2% by weight based on the weight of the entire composition for improving reliability within the range of satisfying the specifications of flame retardant UL 94 V-0. When the flame retardant exceeds the above range, the deterioration in reliability due to chip corrosion by impurity ions under an environment of high temperature, high pressure and humidity is not preferable because it is large.

The epoxy resin composition according to the present invention contributes to lowering the moisture absorption rate and the coefficient of thermal expansion by using a highly filled inorganic filler and improves mechanical strength to ensure excellent semiconductor molding properties and high reliability. More specifically, 7) the inorganic filler is used in the amount of 70 to 91% by weight of fused or synthetic silica having an average particle diameter of 0.1 to 35.0 ㎛. It is preferably used in an amount of 70 to 90.64% by weight, more preferably 70 to 90% by weight. When the amount of the inorganic filler is less than 70% by weight, it is not possible to provide sufficient strength, maintain a sufficiently low coefficient of thermal expansion, and easily penetrate moisture, resulting in poor reliability. On the other hand, when the amount of the inorganic filler used is more than 91% by weight, the flow characteristics of the resin deteriorate and moldability is not good.

In addition to the components 1) to 7), the epoxy resin composition according to the present invention may be a release agent of a higher fatty acid, a natural fatty acid, a paraffin wax, or an ester wax within a range that does not impair the object of the present invention; Carbon black; Coloring agents of organic and inorganic dyes; Crosslinking enhancers; Flame retardant aids; And one or two or more 8) additives selected from the group consisting of leveling agents.

The epoxy resin composition is uniformly pulverized and mixed with a predetermined amount in a Henschel mixer or a Lodige mixer to obtain a primary powdered product, which is then melted and kneaded in a roll mill or kneader at a temperature of 85 to 120 ° C. within 10 minutes and then cooled. And milling.

Hereinafter, the structure and effect of the present invention will be described in more detail with specific examples and comparative examples, but these examples are only intended to more clearly understand the present invention, and are not intended to limit the scope of the present invention.
EXAMPLE

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Example of manufacture :

1.0 mol of diglycidyl ether bisphenol A (molecular weight 228) and 2.0 mol of epichlorohydrin were added to a round-necked flask reaction tube, and then 0.02 mol of 2-methylimidazole aqueous solution was slowly added dropwise into the flask at a reaction temperature of 130 to 220 ° C. After reacting for 6 hours under nitrogen atmosphere while cooling to 10 ° C. or less, 50% sodium hydroxide solution was added thereto. At this time, the temperature was kept below 10 ℃ and reacted for about 4 hours. The mixture thus obtained was mixed with methanol and water, and then purified through strong stirring. A diglycidyl ether bisphenol-modified epoxy resin having an equivalent weight of 300 was prepared through a drying process.

Examples 1 to 3:

Using the diglycidyl ether bisphenol modified epoxy resin prepared above in the composition shown in Table 1 below, using a Henschel mixer, uniformly ground and mixed to obtain a primary powder product, using a roll mill at 100 ℃ After melt-kneading in about 10 minutes and cooled and pulverized to prepare an epoxy encapsulation composition:

Composition Example 1 Example 2 Example 3 Epoxy resin ¹⁾ Cresol Noble Epoxy Resin 8.0 6.3 4.2 ²⁾ diglycidyl ether bisphenol-modified epoxy resin 3.02 4.8 6.8 ³⁾ brominated epoxy resin 1.0 1.0 1.0 Antimony trioxide 0.26 0.25 0.26 Phenolic Noblec Hardener 2.0 2.5 3.5 Multifunctional Phenolic Resin (Molecular Weight) 3.6 3.04 2.07 Triphenyl phosphine 0.17 0.15 0.17 ⁴⁾ latent curing catalyst 0.15 0.10 0.10 Inorganic filler 81 81 81 Carbon black 0.25 0.25 0.25 ⁵⁾ Coupling Agent 1 0.20 0.28 0.30 ⁶⁾ Coupling Agent 2 0.10 0.08 0.07 ⁷⁾ Coupling Agent 3 - - 0.03 Carnauba Wax 0.25 0.25 0.25
Note: 1) Japanese gunpowder: EOCN-1020-65; 2) diglycidyl ether bisphenol-modified epoxy resin of the above production example; 3) Japanese gunpowder: Bren-S; 4) SHIKOKU (四 國 chemical): 2,4-diamino-6- (2-2-methyl-1-imidazole) ethyl-1,3,5-triazine; 5) Coupling Agent 1: γ-glycithoxy propylene methoxy silane; 6) coupling agent 2: imidazole silane; 7) Coupling agent 3: γ-merceto propylene methoxy silane.

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The physical properties and the reliability of the obtained epoxy resin composition were evaluated and shown in Tables 3 and 4 below.

Comparative Examples 1 to 3:

To prepare a composition in the same manner as in Example except that it was formulated with the composition shown in Table 2 below:

Composition Comparative Example 1 Comparative Example 2 Comparative Example 3 Epoxy resin ¹⁾ Allsocresol Noblock Epoxy Resin 11.0 9.0 6.0 Biphenyl Epoxy Resin (YX-4000H) - 2.0 5.0 ³⁾ brominated epoxy resin 1.0 1.0 0.80 Antimony trioxide 0.3 0.3 0.20 Phenolic Novolac Curing Agent 3.45 3.87 5.69 Multifunctional Phenolic Resin 2.0 1.5 - Triphenyl phosphine 0.2 0.18 0.16 ⁴⁾ latent curing catalyst 0.10 0.10 0.15 Inorganic filler 81 81 81 γ-glycithoxypropyl trimethoxy silane 0.30 0.30 0.25 Carbon black 0.25 0.25 0.25 Carnauba Wax 0.2 0.20 0.2 ⁵⁾ Coupling Agent 1 0.2 0.3 0.3
Note: 1) ~ 5): same as Table 1

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The physical properties and the reliability of the obtained epoxy resin composition were evaluated and shown in Tables 3 and 4 below.

Evaluation Item Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Spiral Flow (inch) 29 32 34 28 35 40 Glass transition temperature Tg (℃) 170 163 152 180 165 142 Coefficient of thermal expansion α1 (㎛ / m, ℃) 16.9 11.8 10.2 17.2 11.2 10.0 Adhesion (Kgf) 71 69 80 34 47 58 Flexural Modulus (kg / ㎠) 2050 1940 1880 2300 2160 1930

Physical property evaluation method

Flow Spiral Flow: The mold is manufactured on the basis of EMMI standard, and the flow length is evaluated at molding temperature (175 ℃) and molding pressure 70Kgf / cm ² .

㉡ Glass transition temperature (Tg) and coefficient of thermal expansion: evaluated by TMA (Thermal mechanical Analyser) (heating rate 10 ℃ / min).

㉢ Adhesion: Measure tensile force between Kapper Lead Frame and epoxy encapsulant using UTM.

㉣ Flame retardant: UL 94 vertical test based on 1 / 16inch. After the flame has been in contact with the specimen for 10 seconds, once the flame has been extinguished, perform five tests for contacting the flame again for 10 seconds.
Evaluation Item Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 crack Before IR REFLOW 0/128 0/128 0/128 0/128 0/128 0/128 After IR REFLOW 0/128 0/128 0/128 18/128 4/128 0/128 Peeling 100 Cycle 0/100 0/100 0/100 4/100 0/100 0/100 200 Cycle 0/100 0/100 0/100 - 3/100 0/100 500 Cycle 0/100 0/100 0/100 - - 1/100 Chip, Pad Peeling 10% or more Defective / Total Test Samples

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`` Reliability, Peeling and Crack Resistance Evaluation ''

First, a small outline package type semiconductor device was molded at 175 ° C. for 90 seconds using an MPS (Multi Plunger System) molding machine, and then cured after 175 ° C. for 4 hours, three times using IR REFLOW temperature as 265 ° C. After the process, the interface between the lead frame, lead-on chip and epoxy encapsulant is inspected using ultrasonic wave (C-SAM) to inspect package cracks. Peeling evaluation was performed with the number of the semiconductor elements which the crack with respect to the number generate | occur | produced. 50, 150, and 200 Cycle harsh tests were performed with a Thermal Shock Tester at a high temperature of 165 ° C. and a low temperature of −65 ° C. for 10 minutes, respectively.

As can be seen from Tables 3 and 4, when the epoxy resin composition according to the present invention was used, the adhesion properties between the epoxy encapsulant, the lead-on chip and the lead frame were excellent, and the reliability was excellent.

By using the epoxy resin composition according to the present invention, it is possible to improve the peeling problem that occurs between the wafer chip surface and the epoxy encapsulant in the semiconductor device encapsulation process, and has excellent mechanical properties, insulation properties and hygroscopic properties, and a solder temperature of 265 ° C. Even when applied to the Pb free solder process, cracks hardly occur on the pad surface and the chip, and high reliability of the manufactured device can be guaranteed.

Claims (3)

1) 5 to 16% by weight of a mixture of cresol noblock epoxy resin and glycidyl ether bisphenol modified epoxy resin; 2) 4 to 9% by weight of bifunctional or polyfunctional phenolic resins and phenol noblock resins as curing agents; 3) 0.2 to 2.0 wt% of an alkyl alkoxy silane containing an epoxy group at the end and an alkyl alkoxy silane containing an imidazole group at the end as a coupling agent; 4) 0.05 to 0.40% by weight of latent curing catalyst; 5) 0.01 to 0.2 wt% of a cocatalyst of the latent curing catalyst; 6) 0.1 to 2 weight percent of a flame retardant; And 7) an epoxy resin composition for sealing a semiconductor device comprising an inorganic filler 71 to 90% by weight, wherein the glycidyl ether bisphenol-modified epoxy resin is obtained by reacting diglycidyl ether bisphenol monomer with epichlorohydrin An epoxy resin composition is a polymer represented by Formula 1 below, and the alkyl alkoxy silane including the imidazole group is a compound represented by Formula 5 below: [Formula 1]

(Wherein R is a hydrogen atom or a methyl group, G is a glycidyl group and n is an integer of 0 to 3); And [Formula 5]

(Wherein R ¹ , R ² , R ³ , and R ⁴ are each independently of each other hydrogen or an alkyl group having 1 to 6 carbon atoms, n is an integer of 1 to 3). The method of claim 1, wherein 4) the latent curing catalyst is a triazine isocyanate imidazole compound, tetraphenylphosphonium tetraphenyl borate, triphenylphosphine tetraphenyl borate or tetraphenyl boron salt; 5) the cocatalyst of the latent curing catalyst is benzyldimethylamine, triethanolamine, triethylenediamine, dimethylaminoethanol, tri (dimethylaminomethyl) phenol, triphenylphosphine, diphenylphosphine or phenylphosphine; 6) The flame retardant is an epoxy resin composition, characterized in that the epoxy equivalent of 250 to 400, a mixture of brominated phenol epoxy and antimony trioxide having a bromine content of 35 to 50% by weight based on the flame retardant epoxy. The epoxy resin composition of claim 1, wherein a mixing ratio of the cresol noblock epoxy resin and the glycidyl ether bisphenol-modified epoxy resin is 80:20 to 20:80.