KR100611459B1 - Epoxy Resin Composition for Encapsulating Semiconductor Device - Google Patents

Abstract

The present invention relates to an epoxy resin composition for sealing semiconductor devices, and more particularly, to use a polyaromatic epoxy resin and a polyaromatic curing agent, without using a halogen flame retardant and a phosphorus flame retardant, which are harmful to a human body or a device. The present invention relates to an epoxy resin composition for sealing a semiconductor device that uses a phosphazene and selectively mixes zinc borate to achieve flame retardancy.

Halogen flame retardant, phosphorus flame retardant, polyaromatic epoxy resin, polyaromatic curing agent, phosphazene, zinc borate

Description

Epoxy Resin Composition for Encapsulating Semiconductor Device

The present invention relates to an epoxy resin composition for sealing semiconductor elements, and more particularly, to an epoxy resin composition for flame retardant semiconductor elements sealing free of halogen.

In general, flame retardancy is required in manufacturing an epoxy resin for semiconductor encapsulant, and most semiconductor companies require a flame retardancy of UL-94 V-0 level. In order to secure such flame retardancy, a flame retardant is used to manufacture an epoxy resin for a semiconductor encapsulant, and bromine epoxy and antimony trioxide are mainly used to prepare an epoxy resin for a semiconductor encapsulant to ensure flame retardancy. In other words, bromine or chlorine halogen-based flame retardants and antimony trioxide having excellent flame retardant synergistic effects are widely used as flame retardants as flame retardants for imparting flame retardancy in the manufacture of epoxy resins for semiconductor encapsulants. However, in the case of an epoxy resin for a semiconductor encapsulant having flame retardancy using such a halogen-based flame retardant, it is known that toxic carcinogens such as dioxin or difuran are generated during incineration or fire. In addition, halogen-based flame retardants are toxic to humans due to gases such as HBr and HCl generated during combustion, and are the main cause of corrosion of semiconductor chips, wires, and lead frames. There is a problem such as working. As a countermeasure, new flame retardants such as phosphorus flame retardants such as phosphazene and phosphate esters and nitrogen element-containing resins have been considered. However, phosphorus flame retardants in nitrogen element-containing resins are insufficient in flame retardancy and phosphorus flame retardants are combined with moisture. And polyphosphoric acid has a problem of deteriorating the reliability of the semiconductor.

The present invention is to solve the problems of the prior art as described above, without using a halogen-based flame retardant and phosphorus-based flame retardant harmful to the human body or equipment, using a multi-aromatic epoxy resin and a multi-aromatic curing agent, which is an inorganic flame retardant An object of the present invention is to provide an epoxy resin composition for sealing a semiconductor device that uses flamen and optionally mixes zinc borate to achieve flame retardancy.

That is, the present invention (1) modified epoxy produced by glycidyl etherification of a mixture of a phenolic compound having a novolak structure represented by the following general formula (1) and a 4,4'-dihydroxy biphenyl represented by the following general formula (2): Suzy;                         

[Formula 1]

Where n (mean value) is a real number between 1.15 and 2.30

[Formula 2]

(2) a curing agent represented by the following formula (3);

[Formula 3]

(Where n is a real number of 1 to 6)

(3) phosphazene represented by the following formula (4) as a flame retardant;

[Formula 4]

(Wherein R and R 'are each hydrogen or methyl and n is an integer from 0 to 4)                         

(4) curing accelerators;

(5) modified silicone oils; And

(6) The present invention relates to an epoxy resin composition for sealing semiconductor elements containing an inorganic filler as an essential component.

The present invention will be described in more detail below.

In the present invention, a phenolic compound having a novolac structure containing a biphenyl derivative in a molecule represented by the following general formula (1) as an epoxy resin, and 4,4'-dihydroxy biphenyl represented by the general formula (2) It is characterized by using a polyaromatic modified epoxy produced by glycidyl etherification of a mixture of hereinafter ('phenol mixtures').

In the above formula, n (average value) is a real number of 1.15 to 2.30.

The preparation of the modified epoxy resin is preferably a method of glycidyl etherification of the phenol mixture and epichlorohydrin, which is most commonly used industrially, under alkali, and glycidylation reaction itself is commonly known. It can be done through the method.

On the other hand, if the weight ratio of the material represented by the formula (1) in the modified epoxy resin is increased flame retardancy properties of the epoxy resin composition has an advantage in terms of flame retardancy, but if the weight ratio exceeds 85% by weight of the modified epoxy resin obtained therefrom There is a disadvantage in that is not suitable for high filling of the inorganic filler and the flow characteristics are reduced. In addition, when the content of 4,4'-dihydroxy biphenyl represented by the formula (2) exceeds 50% by weight, the modified epoxy resin obtained from this mixture is difficult to control the reaction during curing, and the reaction rate is delayed, thereby preparing the The epoxy resin composition for sealing a semiconductor device has a problem of lowering productivity by causing molding defects in molding operations using transfer molding. As a result of comprehensive examination of such properties, the weight ratio of the material represented by the formula (1) in the phenol mixture when preparing the modified epoxy resin of the present invention is 50 to 85% by weight, more preferably 70 to 80% by weight It is preferable because the epoxy resin composition of flame retardancy, high fluidity, and low hygroscopicity can be provided.

The polyaromatic modified epoxy resin applied to the present invention has a structure having a biphenyl in the middle based on a phenol skeleton, and thus has excellent hygroscopicity, toughness, oxidation resistance, and crack resistance. In addition, the crosslinking density is low to form a carbon layer (char) during combustion at high temperature to ensure flame retardancy.

The content of the polyaromatic epoxy resin in the total composition is in the range of 3.4 to 15% by weight.

In addition to the modified epoxy resin may be used in addition to biphenyl, ortho cresol novolak resin, but in order to ensure the flame retardancy of the epoxy resin composition for semiconductor sealing the modified epoxy resin in the total epoxy resin 40% by weight or more, It is preferable to mix | blend 60 weight% or more preferably.

In the composition of the present invention as a curing agent is used a multi-aromatic curing agent represented by the formula (3).

N is a real number of 1-6 in said formula.

The multi-aromatic curing agent reacts with the multi-aromatic epoxy resin to form a carbon layer (char) to achieve flame retardancy by blocking the transfer of heat and oxygen around. The content of the multiaromatic curing agent in the total composition is in the range of 2 to 10.5% by weight.

As the curing agent component, in addition to the polyaromatic curing agent, a phenol novolak resin or xylol resin may be further included.

In the composition of the present invention, as a flame retardant, phosphazene represented by the following Chemical Formula 4 is basically used, and zinc borate represented by the following Chemical Formula 5 may be selectively mixed.

Wherein R and R 'are each a hydrogen atom or a methyl group, and n is an integer of 0 to 4.

The phosphazene has a decomposition temperature of 350 ° C., which is excellent in moisture resistance and heat resistance, and forms a carbon layer (char) upon combustion at high temperatures to block external oxygen and heat, thereby exhibiting a flame retardant effect. Meanwhile, the zinc borate has a melting point of 260 ° C., excellent heat resistance, electrical properties, and moisture resistance, and exhibits endothermic phenomenon as the dehydration reaction occurs at a high temperature, and a flame retardant effect is large due to an endothermic amount of 530 J / g. In addition, the decomposed combustion products form a stable carbon layer (char), resulting in an excellent flame retardant effect than conventional halogen-based flame retardants. The content of flame retardant in the total composition is in the range of 0.5 to 5% by weight.

In the composition of the present invention, the curing accelerator is a component necessary for promoting the curing reaction of the epoxy resin and the curing agent component, for example benzyldimethylamine, triethanolamine, triethylenediamine, dimethylaminoethanol, tri (dimethylaminomethyl) phenol Tertiary amines such as these, imidazoles such as 2-methylimidazole and 2-phenylimidazole, organic phosphines such as triphenylphosphine, diphenylphosphine, phenylphosphine, and tetraphenylphosphonium tetra Tetraphenyl boron salts, such as a phenyl borate and a triphenyl phosphine tetraphenyl borate, etc. can be used individually or in mixture of 2 or more types. The content of the curing accelerator in the total composition is in the range of 0.1 to 0.3% by weight.

In the composition of the present invention, the modified silicone oil is a silicone polymer having excellent heat resistance, and a silicone oil having an epoxy functional group, a silicone oil having an amine functional group, a silicone oil having a carboxyl functional group, or the like is mixed Can be used, the content of the modified silicone oil in the total composition is in the range of 0.1 to 1.5% by weight. When the silicone oil is used in excess of 1.5% by weight, surface contamination is likely to occur and the resin bleed may be long, and when used at less than 0.1% by weight, sufficient low modulus of elasticity may not be obtained.

In the composition of the present invention, as the inorganic filler, it is preferable to use molten or synthetic silica having an average particle of 0.1 to 35 µm, and the filling amount should be 73 to 90% by weight based on the whole composition. When the inorganic filler is used in an amount less than 73% by weight, sufficient strength and low thermal expansion cannot be realized, and moisture permeation becomes easy, and it becomes fatal to reliability characteristics. In addition, when the amount of the inorganic filler is greater than 90% by weight, there is a fear that the moldability is deteriorated due to the deterioration of the flow characteristics.

Coupling agents such as release agents such as higher fatty acids, higher fatty acid metal salts, ester waxes, colorants such as carbon black and organic dyes, epoxy silanes, amino silanes, and alkyl silanes, in addition to the above components, without departing from the object of the present invention. Etc. can be used as needed.

As a general method for producing an epoxy resin composition using the raw materials described above, a predetermined amount is uniformly mixed sufficiently using a Henschel mixer or a solid mixer, followed by melt kneading with a roll mill or a kneader, followed by cooling and grinding. A method of obtaining the final powder product is used.

As a method of sealing a semiconductor element using the epoxy resin composition obtained in the present invention, a low pressure transfer molding method is most commonly used, or an injection molding method or a casting method can be used.

For the purpose of illustrating the present invention in more detail with reference to the following examples, the following examples are for the purpose of explanation and are not intended to limit the invention.

Examples 1 and 2

As shown in Table 1, each component was weighed, and then uniformly mixed using a Henschel mixer to prepare a powder-based primary composition, melt-kneading at 100 ° C. for 7 minutes using a mixing 2-roll mill, and then cooled. And through the grinding process to prepare an epoxy resin composition.

About the epoxy resin composition thus obtained, physical properties and reliability were evaluated by the following method. For reliability test, an MPS molding machine was used for 60 seconds at 175 ° C., followed by post-curing at 175 ° C. for 6 hours to produce an MQFP semiconductor device. Table 2 shows the physical properties and flame retardancy, reliability, and moldability test results of the epoxy resin composition according to the present invention. The reliability test was expressed as the degree of package crack occurrence in the thermal shock test.

Comparative Examples 1 and 2

As shown in Table 1, the epoxy resin composition was prepared in the same manner as in Example by weighing each component according to a given composition, and the results of evaluation of physical properties and reliability are shown in Table 2.

Ingredient Example 1 Example 2 Comparative Example 1 Comparative Example 2 Epoxy resin Multiaromatic Modified Epoxy Resin 3.4 7.2 - - Orthocresol novolac - - 3.3 2.2 Biphenyl 2.3 - 2.2 3.3 Hardener Multi-aromatic 4.9 5.9 4.6 - Xylock - - - 4.6 Flame retardant Phosphazene 0.5 1.0 - - Zinc borate - 0.5 - - Brominated epoxy resin - - 0.3 0.7 Antimony trioxide - - 0.7 0.3 Curing accelerator 0.2 0.2 0.2 0.2 Silica 87.5 84 87.5 87.5 Epoxy silicone oil 0.3 0.3 0.3 0.3 γ-glycidoxypropyltrimethoxysilane 0.4 0.4 0.4 0.4 Carbon black 0.2 0.2 0.2 0.2 Carnauba Wax 0.3 0.3 0.3 0.3 Sum 100 100 100 100

Evaluation item Example 1 Example 2 Comparative Example 1 Comparative Example 2 Spiral Flow (inch) 43 45 40 42 Tg (℃) 128 134 128 120 Electrical Conductivity (μs / cm) 15 21 12 13 Flexural Strength (kgf / mm ² at 24 ℃) 17 15 16 16 Flexural modulus (kgf / mm ² at 24 ℃) 2350 2100 2400 2410 Flame retardant UL 94 V-0 V-0 V-0 V-0 V-0 responsibility Crack Resistance Evaluation 0 0 2 One Total number of semiconductor devices tested 2,400 2,400 2,400 2,400 Formability Void occurrence number (Visual Inspection) 0 0 0 One Total number of semiconductor devices tested 64 64 64 64

[Property evaluation method]

1) Spiral Flow

Molds are manufactured based on EMMI standard to evaluate the flow length at molding temperature (175 ℃) and molding pressure 70Kgf / cm ²

2) Glass transition temperature (Tg)

Assessed by TMA (Thermomechanical Analyser)

3) Electrical conductivity

The cured EMC test piece was crushed to a particle size of about # 400MESH to # 100MESH in a crusher, and weighed 2g ㅁ 0.2mg of powdered sample into an extraction bottle. Measure the conductivity using the supernatant of.

4) Flexural strength and flexural modulus: Hardened EMC molded specimens (125 X 12.6 X 6.4 mm) were prepared and the width and thickness of the center of the specimen were measured using a micrometer up to 0.001 mm and measured using a UTM tester.

5) Flame retardant

Evaluated according to UL 94 V-0

6) Crack resistance evaluation (reliability test)

After pre-condition, after 1,000 cycles in the Thermal Shock Environment Tester, the nondestructive tester SAT (Scanning Acoustic Tomograph) assesses the occurrence of cracks.

(a) Precondition

SOJ-type semiconductor device made of epoxy resin composition was dried at 125 ° C for 24 hours, and then subjected to 5 cycles of thermal shock test, and then left for 168 hours under 85 ° C / 85% relative humidity condition, followed by IR for 235 ° C and 10 seconds. Three passes through the reflow are used to first evaluate the presence of package cracks under precondition conditions. If cracks occur at this stage, the next stage, the 1,000 cycle thermal shock test, is not conducted.

(b) thermal shock test

After 1,000 cycles of leaving the semiconductor package that passed the preconditions for 10 minutes at -65 ° C, 5 minutes at 25 ° C, and 10 minutes at 150 ° C for 1 cycle, the inside of the semiconductor package was SAT. And external cracks are evaluated.

 The present invention can provide an epoxy resin composition for sealing a semiconductor device that achieves the UL 94 V-0 standard without using a halogen flame retardant harmful to a human body or a device.

Claims (6)

(1) 3.4-15 weight of modified epoxy resin produced by glycidyl etherification of the mixture of the phenolic compound of the novolak structure represented by following General formula (1), and the 4,4'- dihydroxy biphenyl represented by following General formula (2) %; [Formula 1]

Where n (mean value) is a real number between 1.15 and 2.30 [Formula 2]

(2) 2 to 10.5% by weight of a curing agent represented by the following formula (3); [Formula 3]

(Where n is a real number of 1 to 6) (3) 0.5 to 5% by weight of phosphazene represented by the following formula (4) as a flame retardant; [Formula 4]

(Wherein R and R 'are each hydrogen or methyl and n is an integer from 0 to 4) (4) 0.1 to 0.3 wt% of a curing accelerator; (5) 0.1-1.5 wt% of modified silicone oil; And (6) The epoxy resin composition for semiconductor element sealing which contains 73-90 weight% of inorganic fillers as an essential component. 2. The semiconductor element sealing method according to claim 1, wherein in the modified epoxy resin, a mixing ratio of the phenol compound of the novolak structure and 4,4'-dihydroxy biphenyl is 50:50 to 85:15. Epoxy resin composition. delete The epoxy resin composition for sealing a semiconductor device according to claim 1, further comprising zinc borate represented by the following formula (5) as a flame retardant. [Formula 5]

The epoxy resin composition for semiconductor element sealing according to claim 1, further comprising a biphenyl resin or an ortho cresol novolac epoxy resin. The epoxy resin composition for sealing a semiconductor device according to claim 1, further comprising a phenol novolak resin or a xylox resin as the curing agent.