JP4496932B2 - Liquid encapsulating resin composition for semiconductor and semiconductor device using the same - Google Patents

Description

  The present invention relates to a liquid sealing resin composition for a semiconductor and a semiconductor device using the same.

  As a sealing material for protecting a semiconductor of a semiconductor package, a sealing material mainly made of an organic resin is used. Among them, liquid sealing resins are often used in sealing applications of E-BGA (Enhanced ball grid array) and FCBGA (Flip chip BGA). Generally, the liquid sealing resin is composed of an epoxy resin, a curing agent, and an inorganic filler. Since the semiconductor sealing application is required to have high reliability, the required characteristics of the sealing material are strict and the constituent materials are limited. For example, bisphenol type epoxy resin is used as the epoxy resin, and acid anhydride, aromatic amine, phenol resin, etc. are used as the curing agent. (See Non-Patent Document 1, Patent Documents 1, 2, and 3) These epoxy resin / curing agent combinations are generally cured at a temperature of about 150 ° C. to 170 ° C. over several hours.

On the other hand, in recent semiconductor packages, a low dielectric constant material is formed on an insulating film of a semiconductor circuit in order to improve electrical characteristics. However, the insulating layer is very fragile due to its characteristics and is easily affected by the stress of the adjacent sealing resin. In addition, since lead-free solder is used as a member used for connection from the viewpoint of environmental measures, the level of reliability has become stricter. These changes are a factor in which low stress is particularly important in the properties of the sealing material. The cause of stress generation in the encapsulant is complicated, but 1) curing shrinkage based on the curing-cooling process, linear shrinkage due to linear expansion. 2) The stress etc. which generate | occur | produce by the relationship between the linear expansion coefficient of a hardened | cured material, an elastic modulus change, etc. and those physical properties of a package structural member are mentioned. Of these, regarding the generation of stress due to the former shrinkage, the curing temperature is one of the important parameters, and it is advantageous that the temperature difference between curing and cooling is small. As described above, the curing temperature so far is about 150 ° C., and how to lower the temperature condition is important. However, the conventional sealing materials have problems in productivity, such as taking time to cure at a lower temperature and incomplete curing. Therefore, a method of adding a curing accelerator is considered in order to cure in a short time. For example, Patent Document 4 expresses low-temperature curability by adding a specific curing accelerator to an epoxy resin / aromatic amine system. However, in the literature examples, in the case of epoxy resin / aromatic amine / curing accelerator / filler, the viscosity change at 25 ° C. is approximately doubled after 24 hours from the initial stage. This increase is due to the fact that, in the case of FCBGA sealing applications, a certain amount of resin is filled in a narrow space by capillary action, and when industrial production is taken into consideration, such a change in viscosity is the occurrence of voids. This increases the process time and is not preferable.
Thus, the present condition is that the material which satisfy | fills low-temperature sclerosis | hardenability and storability simultaneously is hardly found.
Epoxy Resin Technology Association, "Review Epoxy Resin" Epoxy Resin Technology Association (2004) JP-A-10-158365 JP-A-10-158366 JP 2000-23989 A JP 2001-316666 A

  An object of the present invention is to provide a liquid sealing resin composition that can be cured at a low temperature, and to obtain a more reliable semiconductor device by sealing using the liquid sealing resin composition. To do.

Such an object is achieved by the present invention described in [1] to [ 5 ] below.
[1] A liquid encapsulating resin composition for a semiconductor comprising an epoxy resin (A), an aromatic amine (B), and a nitrogen-containing cyclic carboxylic acid (C) which are liquid at 25 ° C. as essential components.
[2] The liquid sealing resin composition for a semiconductor according to [1], wherein the liquid sealing resin composition further contains an inorganic filler (D).

[ 3 ] The item [1] or [ 2 ], wherein the nitrogen-containing cyclic carboxylic acid (C) is pyridinecarboxylic acid, pyridinedicarboxylic acid, pyrazinecarboxylic acid, pyrazinedicarboxylic acid, quinolinecarboxylic acid, or citrazic acid. Liquid encapsulating resin composition for semiconductors.
[ 4 ] The amount of the nitrogen-containing cyclic carboxylic acid (C) added is 1 to 20 parts by weight with respect to 100 parts by weight of the aromatic amine (B), according to any one of items [1] to [ 3 ]. The liquid sealing resin composition for semiconductors as described.
[ 5 ] A semiconductor device obtained by being sealed with the liquid sealing resin composition for semiconductor according to any one of [1] to [ 4 ].

  According to the present invention, it becomes possible to seal a semiconductor without spending time at a lower temperature than in a conventionally known formulation, reducing the generation of stress due to a temperature difference, and obtaining a more reliable semiconductor package. Can do.

As the epoxy resin used in the present invention, any known epoxy resin that is liquid at 25 ° C. can be applied. A more preferred structure is an aromatic glycidyl ether having two or more glycidyl groups per molecule. Furthermore, since it is used for a semiconductor use, it is preferable that there are few ionic impurities. More preferably, the amount of hydrolyzable chlorine is 500 ppm or less.
The curing agent used in the present invention is limited to aromatic amines. More preferably, it is liquid at 25 ° C. As an example, an oligomer type curing agent having a structure represented by the following general formula (1) can be mentioned.

For example, an aromatic amine of R = H, X = C ₂ H _{5 and} an aromatic amine of R = CH ₃ , X = H are preferable because they are liquid at room temperature and excellent in reliability. Examples other than the oligomer-based curing agent include diethyltoluenediamine and dimethylthiotoluenediamine.
The ratio of the curing agent to the epoxy resin is preferably in the range of 0.5 to 1.2 relative to the epoxy equivalent as active hydrogen. Deviating from this range is not preferable because the physical properties of the cured product are remarkably lowered. In the range of 0.5 to 0.8, it is preferable to add a co-curing agent such as imidazoles and hydrazide compounds.

  The nitrogen-containing cyclic carboxylic acid used in the present invention is a compound having a carboxyl group in a heterocyclic ring containing a nitrogen atom. Examples of such nitrogen-containing cyclic carboxylic acids include pyridine-2-carboxylic acid, pyridine-3-carboxylic acid, pyridine-4-carboxylic acid, 2,3-pyridinedicarboxylic acid, 2,4-pyridinedicarboxylic acid, 2,5-pyridinedicarboxylic acid, 2,6-pyridinedicarboxylic acid, 3,4-pyridinedicarboxylic acid, 3,5-pyridinedicarboxylic acid, imidazole-4,5-dicarboxylic acid, quinaldic acid, citrazic acid, cheridamic acid, Examples include pyrazinecarboxylic acid, pyrazine-2,3-dicarboxylic acid, 3,5-pyrazoledicarboxylic acid, quinaldic acid, 4-quinolinecarboxylic acid, and 8-quinolinecarboxylic acid.

  The addition amount of these nitrogen-containing cyclic carboxylic acids is preferably 1 to 20 parts by weight with respect to 100 parts by weight of the curing agent (B). When it is less than 1, the low temperature curing action of the present invention is not exhibited. If it exceeds 20 parts by weight, it is not preferable because the cured properties and storage stability are lowered. In addition, these nitrogen-containing cyclic carboxylic acids generally have a high melting point, but in the present invention, it is preferable to disperse them in the resin composition as they are in a solid state. More preferably, the solid particles are finely pulverized and sieved. Specifically, it is preferable that the particle size is 10 μm or less.

Addition of acids, phenols, alcohols and the like as epoxy resin / aromatic amine curing accelerators is known. However, these additions remarkably deteriorate the storage stability, and therefore cannot be applied to the use as in the present invention.
The nitrogen-containing cyclic carboxylic acid used in the present invention decreases the acidity of the carboxylic acid due to the electronegativity of nitrogen, and the promotion of the reaction is suppressed in the working environment. However, when the temperature rises, the reaction activity rapidly appears. Therefore, it is possible to cure the resin at a lower temperature and an appropriate curing time than in the past.

  An inorganic filler can be used for the liquid sealing resin composition of the present invention. Examples of the inorganic filler used in the present invention include silicates such as talc, fired clay, unfired clay, mica, and glass, oxides such as titanium oxide, alumina, silica, and fused silica, calcium carbonate, magnesium carbonate, and hydrotalc. Carbonate such as sites, hydroxides such as aluminum hydroxide, magnesium hydroxide, calcium hydroxide, sulfates or sulfites such as barium sulfate, calcium sulfate, calcium sulfite, zinc borate, barium metaborate, aluminum borate And borate salts such as calcium borate and sodium borate, and nitrides such as aluminum nitride, boron nitride and silicon nitride. Among these, silica, particularly spherical fused silica is preferable. Thereby, fluidity | liquidity and supply stability can be improved. Although the average particle diameter of a filler is not specifically limited, 10 micrometers or less are preferable and especially 5 micrometers or less are preferable. When the average particle diameter is within the above range, the filling property can be particularly improved. Furthermore, the surface of the filler may be surface-treated with a coupling agent.

  Depending on the purpose, the liquid sealing resin composition of the present invention includes a crosslinking agent, an organic filler, a compatibilizing agent, a leveling agent, a defoaming agent, a surfactant, an antisettling agent, a colorant, a thixotrope, in addition to the above components. Additives such as additives, antioxidants and solvents can be added depending on the application. These additives can be used alone or in admixture of two or more. As a manufacturing method, it can produce by mixing with a roll, a planetary mixer, etc., and carrying out vacuum defoaming.

  Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.

Example 1
[Preparation of Resin Composition 1]
As an epoxy resin, 100 parts by weight of a bisphenol F-type epoxy resin (EXA-830LVP, manufactured by Dainippon Ink & Chemicals), an aromatic amine (Kayahard A-) in which X = ethyl and R = H in the general formula (1) as a curing agent A, manufactured by Nippon Kayaku Co., Ltd.) 36 parts by weight, 6 parts by weight of γ-glycididooxypropyltrimethoxysilane (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) as a coupling material, and epoxidized polybutadiene (E-700- as a low stress agent) 6.5, manufactured by Nippon Petrochemical Co., Ltd.) 5 parts by weight, citrazic acid (reagent, manufactured by Tokyo Chemical Industry) as a nitrogen-containing cyclic carboxylic acid, 1.8 parts by weight, and carbon black (MA-600, manufactured by Mitsubishi Chemical Corporation) as a colorant Table 1 shows 0.4 parts by weight and 150 parts by weight of spherical silica (average particle size: 0.5 micron, SO-25H, manufactured by Admatechs) as a filler. Formulated I, and kneaded using a three roll mill to prepare a defoamed after liquid sealing resin composition. The following tests were conducted for evaluation.

1) Pot life The viscosity (η1) of the sealing resin immediately after production was measured with an E-type viscometer. (Measurement conditions: 25 ° C., 3 ° cone, 2.54 mmφ, 2.5 rpm)
Further, the resin was stored in a sealed container and left in a constant temperature layer at 25 ° C. for 24 hours, and then the viscosity (η2) was measured under the same conditions.
The viscosity increase rate (pot life) was determined from the following equation.

2) Adhesion (optimal curing conditions)
The prepared liquid sealing resin composition was applied on a BT substrate having a thickness of 1.0 mm on which a solder resist (PSR-4000 / AUS5, manufactured by Taiyo Ink Co., Ltd.) was formed, and a 6 × 6 mm square chip was placed thereon. A test piece cured for a predetermined time (30 minutes, 60 minutes, 90 minutes, 120 minutes...) At 150 ° C. (150 ° C. only in Comparative Example 4) was placed on a 200 ° C. hot plate, and the shear strength was measured. Furthermore, the relationship between the shear strength and the curing time was examined, and the shortest time for the strength to reach the saturation value was determined as the optimum curing condition.
3) DSC
In order to confirm curability, the total reaction heat (ΔH1) of the liquid encapsulating resin composition before curing is measured by DSC (in air, temperature condition: normal temperature to 300 ° C., temperature increase condition: 10 ° C./min). Then, the total calorific value (ΔH2) obtained by measuring the liquid sealing resin composition cured under the optimal curing conditions in the same manner was calculated, the reaction rate was calculated as follows, and 95% or more of the reaction was completed. Considered.

4) Warpage A liquid resin was applied on a BT substrate having a thickness of 1.0 mm and a 45 × 45 mm square on which a solder resist (PSR-4000 / AUS5, manufactured by Taiyo Ink Co., Ltd.) was formed, and a silicon chip (thickness: 350 microns, 10 X10 mm) was placed and cured under the optimum curing conditions obtained in 2), and then the surface of the silicon chip was scanned using a surface roughness meter to determine the difference between the maximum displacement and the minimum displacement, and the amount of warpage was obtained.

Example 2
Table 1 as in Example 1 except that 1.8 parts by weight of citrazic acid used in Example 1 was changed to a combined system of 1.8 parts by weight of citrazic acid and 1.8 parts by weight of 2,4-pyridinedicarboxylic acid. The liquid sealing resin composition was adjusted according to the above, and the same test was performed.
Example 3
36 parts by weight of Kayahard A-A used in Example 1 was replaced with a combined system of 18 parts by weight of Kayahard A-A and 32 parts by weight of curing agent (X = H, R = CH ₃ in the general formula (1)), and A liquid sealing resin composition was prepared according to Table 1 in the same manner as in Example 1 except that 150 parts by weight of spherical silica was changed to 163 parts by weight of spherical silica, and the same test was performed.

Comparative Example 1
A liquid sealing resin composition was prepared according to Table 1 in the same manner as in Example 1 except that 1.8 parts by weight of salicylic acid was used instead of 1.8 parts by weight of citrazic acid in Example 1, and the same test was performed. .
Comparative Example 2
A liquid sealing resin composition was prepared according to Table 1 in the same manner as in Example 1 except that 1.8 parts by weight of bisphenol A was used instead of 1.8 parts by weight of citrazic acid in Example 1, and the same test was performed. .
Comparative Example 3
A liquid sealing resin composition was prepared according to Table 1 in the same manner as in Example 1 except that citrazic acid was not added and 150 parts by weight of spherical silica was changed to 147 parts by weight of spherical silica in Example 1. Went.
Comparative Example 4
A test was conducted in the same manner as in Example 1 (different curing conditions) using a commercially available liquid sealing resin (CRP-4152R5, manufactured by Sumitomo Bakelite Co., Ltd.).

Examples 1, 2, and 3 show values comparable to the adhesiveness compared to the commercially available liquid sealing resin of Comparative Example 4. Moreover, regarding the curing conditions, it was found that the curing temperature can be reduced with the same curing time. Moreover, when the comparative example 3 and Example 1-3 were compared, although there was no difference in a characteristic, the curing time of the comparative example 3 became very long. Regarding the warpage, when Comparative Examples 3 and 4 and Example 1-3 were compared, an improvement was recognized. This is thought to be due to low temperature curing.
Furthermore, although Comparative Examples 1 and 2 exhibited low-temperature curability, the pot life was very poor.

Claims (5)

A liquid encapsulating resin composition for a semiconductor comprising an epoxy resin (A) which is liquid at 25 ° C., an aromatic amine (B), and a nitrogen-containing cyclic carboxylic acid (C) as essential components. The liquid sealing resin composition for semiconductor according to claim 1, wherein the liquid sealing resin composition further contains an inorganic filler (D). The nitrogen-containing cyclic carboxylic acid (C) is, pyridinecarboxylic acid, pyridinedicarboxylic acid, pyrazine carboxylic acid, pyrazine dicarboxylic acid, quinoline carboxylic acid, or a semiconductor for liquid sealing resin according to claim 1 or 2 is citrazinic acid Composition. The liquid sealing for a semiconductor according to any one of claims 1 to 3 , wherein an addition amount of the nitrogen-containing cyclic carboxylic acid (C) is 1 to 20 parts by weight with respect to 100 parts by weight of the aromatic amine (B). Resin composition. The semiconductor device obtained by sealing with the liquid sealing resin composition for semiconductors of any one of Claims 1-4 .