KR100740894B1 - Liquid epoxy resin composition for underfill application and a semiconductor stack package using thereof - Google Patents

Abstract

The present invention relates to a liquid epoxy resin composition for a high reliability semiconductor laminate package underfill, and more particularly, using a low viscosity liquid epoxy resin and an acid anhydride-based curing agent, and having a good gap filling property due to excellent fluidity, and using an inorganic filler. The present invention relates to a liquid epoxy resin composition for semiconductor laminate package underfill, which improves the reliability of a package, thereby comprising 10 to 30% by weight of epoxy resin, 10 to 30% by weight of curing agent, 0.1 to 5% by weight of curing accelerator, and 50 to 80% by weight of inorganic filler. %, And the viscosity is characterized in that 2,000 to 40,000cps.

Liquid epoxy, low viscosity, underfill, acid anhydride, inorganic filler, semiconductor, laminated package

Description

LIQUID EPOXY RESIN COMPOSITION FOR UNDERFILL APPLICATION AND A SEMICONDUCTOR STACK PACKAGE USING THEREOF

The present invention relates to a liquid epoxy resin composition for high reliability semiconductor underfill, and more particularly, a portion that is electrically connected between the unit package of the laminated package mounted by stacking a plurality of unit packages in three dimensions and between the laminated package and the circuit board. It relates to a high reliability liquid epoxy resin composition used as an underfill material to improve thermal and mechanical reliability.

As electronic products become smaller, thinner, more versatile, and larger in capacities, the encapsulation and mounting methods of semiconductor devices and packages are also diversifying. In particular, a three-dimensional stacked chip package (Korea Patent 2003-0002476) manufactured by stacking a plurality of semiconductor devices in three dimensions and a three-dimensional stack package (Korea Patent 2004-0046744) manufactured by stacking a plurality of unit packages in three dimensions Lightweight, shorter, more versatile and larger capacities are accelerating with the package.

However, in the case of the laminated package, when the unit package is thick, the thickness of the final laminate package is so thick that the shortcoming of thin and short reduction of semiconductor products occurs. The solder connection of the ball or the like electrically connects the unit packages, the laminated package, and the printed circuit board. In the case of the package mounted in this way, the mechanical strength becomes very weak due to the thin thickness of the unit package, and when the thermal shock test is performed due to the electrical connection through the solder connection such as the solder ball, Different thermal expansion coefficients induce thermal stress, which may lead to poor reliability of the connection state between the circuit board and the solder balls.

 In particular, recently, the package has been increasingly used in portable electronic devices, memory modules, and the like, and the external mechanical and thermal shock factors are greatly increased in this application as compared to the conventional electronic devices. This external impact involves the destruction of the unit package itself and the breakdown between the unit package and the solder balls, the circuit board and the solder balls.

In order to alleviate the stress caused by mechanical and thermal shock, the process of filling the space between the unit packages, the laminated package and the substrate with a resin is an underfill process, and the material used therein is a liquid underfill material which is a thermosetting resin.

In view of this aspect, low viscosity and high fluidity must be achieved in order to ensure filling by rapid penetration into multilayer gaps within 25 to 600 μm in terms of workability. The coefficient of thermal expansion should be lowered so as not to make a difference, it must be able to withstand mechanical shocks, and the adhesion between packages, that is, adhesion should be good.

The present invention is to solve the problems of the prior art as described above, an object of the present invention, using a low viscosity liquid epoxy resin and an acid anhydride-based curing agent, despite the high inorganic filler content, good gap fillability due to excellent fluidity It is to provide a liquid epoxy resin composition for laminated semiconductor package underfill that has a high mechanical strength, low coefficient of thermal expansion, low absorption rate, and can improve the reliability of the package.

Other objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description of the invention and the preferred embodiments.

Therefore, according to the present invention includes an epoxy resin represented by the following formula (1), a mixture of a curing agent represented by the following formula (2) and formula (3), a curing catalyst represented by the formula (4) and an inorganic filler having a particle size of 0.5 to 20㎛ A highly reliable liquid epoxy resin composition for semiconductor underfill is provided.

[Formula 1]

(Wherein R is hydrogen or a methyl group)

[Formula 2]

(In the formula, R ₁ to R ₃ are each independently an alkyl or alkenyl group having 1 to 4 carbon atoms.)

[Formula 3]

[Formula 4]

(In the formula, R ₁ to R ₄ are each independently one of a hydrogen atom, a methyl group, an ethyl group, a phenyl group, a cyanoethyl group, a benzyl group, and a hydroxyl group.)

The epoxy resin is 10 to 30% by weight, the curing agent is 10 to 30% by weight, the curing catalyst is characterized in that it comprises 0.1 to 5% by weight, the inorganic filler comprises 50 to 80% by weight.

The inorganic filler is characterized in that the particle size of 0.5 ~ 10㎛.

The liquid epoxy resin composition for semiconductor underfill has a viscosity of 2,000 to 40,000 cps.

The epoxy resin is characterized in that any one or a mixture of bisphenol-A, bisphenol-F, hydrogenated bisphenol-A, hydrogenated bisphenol-F having an epoxy equivalent of 150 to 220 and a viscosity of 300 to 5,000 cps.

In addition, according to the present invention, any one or a mixture of naphthalene-based, phenol novolac-based, cycloaliphatic-based, and amine-based polyfunctional epoxy resins is added to the epoxy resin. A composition is provided.

The inorganic filler is characterized in that the fused silica or synthetic silica having a maximum particle size of less than 80㎛.

The curing agent is characterized in that the mixture of Formula 2 and Formula 3.

According to the present invention, there is provided a semiconductor laminated package, which is manufactured using the liquid epoxy resin composition.

Hereinafter, the configuration of the liquid epoxy resin composition for laminated semiconductor package underfill according to the present invention will be described.

The liquid epoxy resin composition for high reliability semiconductor underfill of the present invention comprises an epoxy resin, a curing agent, a curing catalyst and an inorganic filler.

The epoxy resin used in the present invention is a bisphenol-based epoxy resin, bisphenol-A, bisphenol-F, hydrogenated bisphenol-A, hydrogenated epoxy equivalent having a structure of the formula (1) is 150-220, the viscosity is 300-5,000cps Any one or a mixture of bisphenol-F can be used.

[Formula 1]

(Wherein R is hydrogen or a methyl group)

The content of the epoxy resin in the total composition is in the range of 10 to 30% by weight. If the content exceeds the upper limit, there is a problem that the reaction rate is slow and the process time is long, and when used below the lower limit, the physical properties required by the present invention cannot be obtained.

In addition, other liquid epoxy resins, such as naphthalene-based, phenol novolac-based, cyclo aliphatic, and amine-based polyfunctional epoxy resins, may be mixed with the epoxy resin for the purpose of improving physical properties. However, since the viscosity may increase a lot when used in combination with a naphthalene epoxy resin or a phenol novolac epoxy resin, the mixture may be used within the range of maintaining an appropriate viscosity for the purpose of the present invention.

In the present invention, the curing agent is equivalent to 210 to 250, alkylated tetrahydrophthalic anhydride represented by the following formula (2) or methyltetrahydrophthalic anhydride represented by the following formula (3) is used by mixing the equivalent.

(In the formula, R ₁ to R ₃ are each independently an alkyl or alkenyl group having 1 to 4 carbon atoms.)

The mixing weight ratio of the said alkylated tetrahydrophthalic anhydride and methyltetrahydrophthalic anhydride is 30: 70-70: 30. When the ratio of the alkylated tetrahydrophthalic anhydride is less than 30% by weight, the water absorption rate of the liquid encapsulant is high, and the curing shrinkage rate is high, thereby reducing reliability. On the other hand, when the content of the alkylated tetrahydrophthalic anhydride is 70% by weight or more, when the alkylated tetrahydrophthalic anhydride is used alone, the viscosity of the resin composition may increase and workability may be significantly reduced.

The content of the curing agent in the total composition is in the range of 10 to 30% by weight. If the content exceeds the upper limit, there is a problem that uncured residues are formed in the cured product to lower the reliability of the package, and when used below the lower limit, the curing rate may be lowered.

In the present invention, as a curing catalyst, an imidazole catalyst represented by the following Chemical Formula 4 may be used, and when the same amount is used for each type of catalyst, a difference in gelation time may occur depending on activity, but the gelation time may be controlled by increasing or decreasing the amount used. The type of catalyst is not limited.

[Formula 4]

(In the formula, R ₁ to R ₄ are each independently a hydrogen atom, a methyl group, an ethyl group, a phenyl group, a cyanoethyl group, a benzyl group, or a hydroxyl group.)

The content of the curing catalyst in the total composition is in the range of 0.1 to 5% by weight. If the content exceeds the upper limit, the desired curing properties may not be obtained, and the storage stability of the resin composition may be deteriorated. If the content is used below the lower limit, the curing rate is slowed, the productivity is decreased, and the desired physical properties due to uncuring. Problems may not arise.

In addition, the curing catalyst may be a curing catalyst and a curing catalyst modified with a curing agent and encapsulated with a thermoplastic resin to increase the room temperature stability as needed.

In the present invention, as the inorganic filler, it is preferable to use molten silica or synthetic silica having an average particle size of 0.5 to 20 µm, and it is necessary to adjust the average particle size according to the size of the gap to be applied and the content of the inorganic filler. have. In the present invention, the size of the inorganic filler particles is 0.5 to 10㎛, preferably 1 to 5㎛, and the maximum particle size is preferably less than 80㎛. The content of the filler in the total composition is in the range of 50 to 80% by weight. When the content is less than 50% by weight, sufficient strength and low coefficient of thermal expansion cannot be expected, moisture infiltration is easy, and curing shrinkage rate increases, which causes a decrease in reliability. On the other hand, when the content exceeds 80% by weight, the degree of filling varies depending on the viscosity of the resin and the curing agent, but the gap filling speed is significantly lowered due to the deterioration of the flow characteristics.

In addition to the components of the composition described above, antifoaming agents for facilitating the removal of bubbles as necessary without affecting the object of the present invention, colorants such as carbon black for product appearance, etc., glyces for increasing mechanical properties and adhesion. Other additives, such as silane coupling agents such as doxypropyl trimethoxy silane, surface tension modifiers for improving permeability, fumed silica for improving thixotropy and formability, and the like can be further used.

The liquid epoxy resin composition of the present invention can be prepared by, for example, adding an epoxy resin, a curing agent, a curing accelerator, and an inorganic filler at the same time or sequentially for each raw material, and stirring, mixing, and dispersing while heating as necessary. The apparatus for mixing, stirring, and dispersing these mixtures is not particularly limited, but a mixer, a three-axis roll mill, a ball mill, a vacuum induction machine, a planetary mixer, and the like, which are equipped with a stirring and heating device, may be used. It can also be used in combination.

The viscosity of the liquid epoxy resin composition in this invention should be 2,000-40,000cps in 25 degreeC, Preferably it is the range of 3,000-30,000cps or less. In the underfill process, depending on the gap size between the unit package or between the laminated package and the circuit board, if the viscosity is more than 40,000 cps, the gap filling time is too long and workability in the dispensing process may also be poor.

The molding process may use a conventional dispensing process, the curing is preferably cured in an oven at 150 ℃ for 1 hour or more. In some cases, the curing temperature may be changed by adjusting the curing catalyst, and the curing time may be shortened.

The semiconductor laminated package can be provided using the liquid epoxy resin composition of this invention.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the following Examples are for the purpose of explanation and are not intended to limit the present invention.

[Examples 1 and 2, Comparative Examples 1 to 3]

The epoxy resin composition was prepared by stirring, dispersing, and mixing the raw materials with the mixing ratio shown in Table 1 using a ceramic stirrer and a three roll mill. By using the prepared epoxy resin composition, the specimen was cured at 150 ° C. for 1 hour at 150 ° C. to prepare a specimen having a W × T × L of 4 mm × 10 mm × 80 mm, and measured physical properties such as glass transition temperature, bending strength, and coefficient of thermal expansion. The results are shown in Table 1. In the case of workability and reliability test, a specimen was prepared by underfilling a laminated package having two unit packages having a W × L of 11 mm × 21 mm on a substrate mounted on a printed circuit board and curing at 150 ° C. for one hour.

1) DIC Corporation: EXA-835LV

2) DIC Corporation: YH-306

3) DIC: B-570

[Property evaluation method]

1) viscosity

Measured at 25 ° C. using a Brookfield viscometer with Cone & Plate type.

2) glass transition temperature

Evaluated by DMTA (Dynamic Mechanical Thermal Analyser) (raising rate 5 ℃ / min, 1Hz).

3) coefficient of thermal expansion

Evaluation by TMA (Thermomechanical Analyser) (raising rate 10 ℃ / min).

4) Flexural Strength

Assessed according to ASTM D190 using UTM (Universal Test Machine).

5) Curing Shrinkage

Determination of weight loss rate before and after curing.

6) gap filling

 A laminated package in which two unit packages having a W × L of 11 mm × 21 mm are stacked is mounted on a printed circuit board. At this time, the gap is 200㎛ between the unit package, 250㎛ between the laminated package and the printed circuit board, and then the underfill material is applied at one edge of the laminated package at 70 ° C. for 5 minutes, and then the package cured at 150 ° C. for 60 minutes. Utilize C-SAM to check the filling inside the package.

7) Temperature Cycle Test

JEDEC, JESD22-A104 Test Condition G (-40 ℃ / + 125 ℃), and then using C-SAM to check for peeling.

As can be seen from the physical property and reliability evaluation results of Table 1, when the glass transition temperature is higher than the reliability measurement interval, the thermal expansion coefficient satisfies 40 µm / m. appear.

 In order to satisfy this, the content of the inorganic filler should be used more than 50% by weight, but when more than 80% by weight is used, the viscosity of the encapsulant is increased and workability is significantly lowered, causing a defect.

Methyltetrahydrophthalic anhydride has the advantage of showing low viscosity and high glass transition temperature, but has a disadvantage in that the cure shrinkage is large and the impact strength is weak. To overcome this, the reliability was increased by mixing and using alkylated tetrahydrophthalic anhydride alone.

On the other hand, in Comparative Example 1, when the filling rate of the inorganic material is less than 50% by weight, the thermal expansion coefficient with the solder bumps is increased and the thermal stress is increased, which causes breakage at the interface of the solder bumps, causing a poor reliability.

In the case of using methyltetrahydrophthalic anhydride alone in Comparative Example 2 caused poor reliability due to the increase in the curing shrinkage.

In Comparative Example 3, when the content of the inorganic filler exceeds 80% by weight, the viscosity became too high, and the gap filling speed was significantly reduced, thereby failing to function as an underfill material.

When the inorganic filler content of alkylated tetrahydrophthalic anhydride is more than 60wt%, reworking becomes difficult due to the increase of elastic modulus, and the chip breakage occurs because the stress generated during thermal and mechanical reliability evaluation cannot be reduced.

According to the liquid epoxy resin composition for semiconductor laminate package underfill according to the present invention as mentioned above, not only has excellent processability at low viscosity, but also has a sufficiently low thermal expansion coefficient and low curing shrinkage after curing, thereby improving thermal shock resistance and impact resistance. When applied to a laminated package, it is excellent in workability by viscosity control, and exhibits high thermal shock resistance and impact resistance due to low thermal window coefficient and curing shrinkage ratio after curing, and has high reliability characteristics.

Although the present invention has been described in connection with the above-mentioned preferred embodiments, it is possible to make various modifications or variations without departing from the spirit and scope of the invention. Thus, the claims include any such modifications or variations that fall within the spirit of the invention.

Claims (16)

delete delete delete delete delete delete delete delete delete In the resin composition comprising an epoxy resin represented by the following formula (1), a mixture of a compound of the formula (2) and a compound of the formula (3) as a curing agent, a curing catalyst represented by the following formula (4), and an inorganic filler, the average particle diameter of the inorganic filler It is 1-5 micrometers, and the viscosities in 25 degreeC of all the resin compositions are 2,000-25,000 cps, The liquid epoxy resin composition for high reliability semiconductor underfill characterized by the above-mentioned. [Formula 1]

(Wherein R is hydrogen or a methyl group) [Formula 2]

(In the above formula, R ₁ to R ₃ are each independently an alkyl or alkenyl group having 1 to 4 carbon atoms.) [Formula 3]

[Formula 4]

(In the formula, R ₁ to R ₄ are each independently any one of a hydrogen atom, a methyl group, an ethyl group, a phenyl group, a cyanoethyl group, a benzyl group, and a hydroxyl group.) The method of claim 10, wherein the epoxy resin is 10 to 30% by weight, the curing agent is 10 to 30% by weight, the curing catalyst is 0.1 to 5% by weight, the inorganic filler comprises 50 to 80% by weight A liquid epoxy resin composition for high reliability semiconductor underfill. The method according to claim 10, wherein the epoxy resin is any one or a mixture of bisphenol-A, bisphenol-F, hydrogenated bisphenol-A, hydrogenated bisphenol-F having an epoxy equivalent of 150 to 220 and a viscosity of 300 to 5,000 cps. A liquid epoxy resin composition for high reliability semiconductor underfill, characterized in that. The liquid epoxy resin for high reliability semiconductor underfill according to claim 10, wherein any one or a mixture of naphthalene-based, phenol novolac-based, cyclo aliphatic-based, and amine-based polyfunctional epoxy resins is added to the epoxy resin. Composition. The liquid epoxy resin composition for high reliability semiconductor underfill according to claim 10, wherein the inorganic filler is fused silica or synthetic silica having a maximum particle diameter of less than 80 µm. The liquid epoxy resin composition for high reliability semiconductor underfill according to claim 10, wherein the curing catalyst is 1-benzyl-2-methylimidazole. A semiconductor laminate package produced using the liquid epoxy resin composition according to any one of claims 10 to 15.