KR20020054548A - Epoxy molding composition for encapsulating semiconductor device - Google Patents

Abstract

PURPOSE: Provided is an epoxy resin composition for sealing a semiconductor device, which is excellent in formability and corrosion-resistance against aluminum pads even under the condition of high temperature and high humidity. CONSTITUTION: The epoxy resin composition contains: 9.00-15.00wt% of an o-cresol novolac epoxy resin(formula 1); 5.00-10.00wt% of at least one or two curing agents selected from the group consisting of a cresol novolac resin, a dicyclopentadiene resin, and a phenol novolac resin having at least two hydroxy groups and a hydroxy equivalent of 100-200; 0.01-0.40wt% of a triphenyl phosphine-based curing accelerator; 0.10-0.20wt% of a modified silicone oil; 75.00-85.00wt% of an inorganic filler such as fused silica; 0.20-2.00wt% of a thermo polyurethane resin with an isocyanate terminal having a molecular weight of 3000-200000. In the formula, n is 0, 1, or 2.

Description

Epoxy resin composition for encapsulating semiconductor device

The present invention relates to an epoxy resin composition for sealing semiconductor elements, and more particularly, ortho cresol novolac epoxy resin; One or two or more curing agents selected from the group consisting of phenol novolak resins, cresol novolak resins and dicyclopentadiene resins; Curing accelerators; Modified silicone oils; Inorganic fillers; And an isocyanate-terminated thermopolyurethane resin and an epoxy resin composition for sealing semiconductor devices excellent in resistance to corrosion of aluminum pads.

In the resin-sealed semiconductor device, failure occurs due to corrosion of the aluminum pad due to thermal stress and moisture infiltration due to temperature and humidity changes in the external environment. Since the development of ortho-cresol novolac epoxy resin of high purity (Japanese Patent No. 62-26649) and a phenol resin that can replace an acid anhydride curing agent have been developed, The problem of corrosion of the aluminum wiring of the device has been almost solved. In particular, the surface coating of the semiconductor device using a polyimide resin successfully suppressed the corrosion problem of the aluminum wiring by almost 100%.

However, since an aluminum pad used as an electrode needs to be connected to a gold wire, it is in direct contact with the epoxy resin composition, which is likely to cause corrosion, thereby causing fatal defects such as an increase in electrical resistance. to be.

As a method of inhibiting corrosion of a semiconductor device aluminum pad which is currently commonly used, use of high purity epoxy resin and hardening agent, suppression of delamination by addition of an adhesion enhancing agent between the semiconductor device sealing material and the lead frame, and use of ion trapper Decreases the impurity content and decreases the moisture absorption amount due to the high filling of the inorganic filler.

As the most efficient method, a new epoxy resin composition having improved adhesion strength to aluminum pads, low moisture absorption, and low impurity concentration is required. However, until now, satisfactory epoxy resin compositions are required due to the characteristics of the semiconductor and the weakness of the epoxy resin composition. Could not get

An object of the present invention is to solve the problems of the prior art as described above, by adding an isocyanate-terminated thermopolyurethane resin as an adhesion strength enhancer to improve the adhesion strength between the epoxy resin composition and the semiconductor device aluminum pads, It is to provide an epoxy resin composition for sealing semiconductor elements with improved resistance and moldability.

That is, the present invention is characterized in that an isocyanate-terminated thermopolyurethane resin is added in an epoxy resin composition for sealing an ortho cresol novolac-based epoxy resin, a curing agent, a curing accelerator, a modified silicone oil, and an inorganic filler. It provides the epoxy resin composition for sealing semiconductor elements.

Hereinafter, each structural component of the epoxy resin composition for semiconductor element sealing of this invention is demonstrated in detail.

The epoxy resin (hereinafter referred to as component (1)) used in the present invention is a high purity ortho cresol novolac resin having an epoxy equivalent of 180 to 210 having a structure of the following formula (1).

Where n is 0, 1 or 2

The content of the component (1) is preferably 9.00 to 15.00% by weight based on the total composition, it can not achieve the object of the present invention outside the above range.

The curing agent used in the present invention (hereinafter referred to as component (2)) is selected from the group consisting of phenol novolac resins, cresol novolac resins and dicyclopentadiene resins having two or more hydroxyl groups and a hydroxyl equivalent weight of 100 to 200. It is used one or two or more mixtures are used, preferably in terms of price and moldability, at least 50% by weight of the phenol novolak resin of the formula (2) to the total curing agent mixture.

Where n is 0, 1 or 2

The content of the component (2) is determined so that the composition ratio of the epoxy equivalent of the component (1) to the hydroxyl equivalent of the component (2) falls within the range of 0.75 to 1.25. At this time, the content of the component (2) corresponds to 5.00 ~ 10.00% by weight based on the total composition. If the content is less than 5.00% by weight, the curing reaction is not sufficiently achieved. If the content is more than 10.00% by weight, residues are formed in the sealing material, so that the reliability is lowered and it is not economical.

As the curing accelerator (hereinafter referred to as component (3)) used in the present invention, it is preferable to use a triphenylphosphine-based curing accelerator represented by the following formula (3).

The content of the component (3) is preferably 0.01 to 0.40% by weight based on the total composition. If the content is less than 0.01% by weight, the curing rate is slow and the productivity is not good, and if the content is more than 0.40% by weight, the desired curing properties are not obtained, and storage stability is not good.

The modified silicone oil (hereinafter referred to as component (4)) used in the present invention is a conventional epoxy modified silicone oil.

The content of the component (4) is preferably 0.10 to 0.20% by weight based on the total composition, it can not achieve the object of the present invention outside the above range.

As the inorganic filler (hereinafter referred to as component (5)) used in the present invention, it is preferable to use fused silica having an average particle size of 0.1 to 35.0 µm. The form of the silica is preferably a mixed type of the composition ratio of the crushing type and the spherical form of 2 to 8 to 8 to 2.

The content of the component (5) is preferably 75.00 to 85.00% by weight based on the total composition. If the content is less than 75.00% by weight, sufficient strength cannot be realized, and the penetration of moisture becomes easy, which is a fatal cause of corrosion of the aluminum pad. On the other hand, if the content exceeds 85.00% by weight, the flow characteristics of the composition is lowered, which is not good because there is a fear of poor moldability.

In the present invention, an isocyanate-terminated thermopolyurethane resin (hereinafter referred to as component (6)) having a molecular weight of 3000 to 200000 is used as an adhesion strength improving agent for improving the adhesion strength between the epoxy resin composition and the semiconductor element aluminum pad.

The content of the component (6) is preferably 0.20 to 2.00% by weight based on the total composition. If the content is less than 0.20% by weight, the application effect is insignificant, and when the content is more than 2.00% by weight, adverse effects such as increase in hygroscopicity, decrease in curing degree, and decrease in flexural strength are caused.

In addition, the epoxy resin composition of the present invention includes a flame retardant such as bromo epoxy; Flame retardant aids such as antimony trioxide, alumina hydroxide and antimony pentoxide; Mold release agents such as higher fatty acids, higher fatty acid metal salts, and ester waxes; Coloring agents such as carbon black and organic and inorganic dyes; Coupling agents, such as an epoxy silane, an amino silane, and an alkyl silane, etc. can be added as needed.

The epoxy resin composition of the present invention is uniformly sufficiently mixed with the above-described components using a conventional Henssel mixer or Loedige mixer, and then melt kneaded with a roll mill or kneader. It is prepared as a final powder product through a process of cooling, grinding and grinding.

As a method of sealing a semiconductor device using the epoxy resin composition prepared as described above, a low pressure transfer molding method is most commonly used, but it can also be molded by injection or casting.

Hereinafter, the present invention will be described in more detail with reference to examples, but these examples are for illustrative purposes only and should not be construed as limiting the present invention.

Examples 1-4

As shown in Table 1 below, each component was weighed, and then uniformly mixed with a Henschel mixer to prepare a powdery primary composition, melt-kneaded at 100 ° C. for 10 minutes using a mixing 2-roll mill, and then cooled and The final epoxy resin composition was prepared through a grinding process. The physical properties of each of the epoxy resin compositions thus obtained were evaluated, and the evaluation results are shown in Table 1 below.

Comparative Examples 1 to 3

After weighing each component as shown in Table 2 below, an epoxy resin composition was prepared in the same manner as in Example. The physical properties of each of the epoxy resin compositions thus obtained were evaluated, and the evaluation results are shown in Table 2 below.

(Unit: weight%) Ingredient Example 1 Example 2 Example 3 Example 4 Epoxy Resin (Ortho Cresol Novolak Resin) 13.66 13.66 13.66 13.66 Curing agent (phenol novolak resin) 6.94 6.94 6.94 6.94 Triphenylphosphine Curing Accelerator 0.24 0.24 0.24 0.24 Isocyanate Terminated Thermopolyurethane Resin 0.20 0.40 1.00 2.00 Silica 76.0 76.0 76.0 76.0 Epoxy modified silicone oil 0.13 0.13 0.13 0.13 Carbon black 0.27 0.27 0.27 0.27 Carnauba Wax 0.25 0.25 0.25 0.25 Other additives 2.31 2.11 1.51 1.51 Spiral Flow (inch) 33 32 31 27 Thermal strength (Shore-D) 74 73 70 67 Adhesion strength (kgf) 40 42 46 47 Glass transition temperature (℃) 152 151 148 146 Hygroscopicity (wt%) 0.41 0.41 0.43 0.46 Corrosion frequency 0/50 0/50 0/50 0/50 Formability (number of sticking occurrences) 0/50 0/50 0/50 0/50

(Unit: weight%) Ingredient Comparative Example 1 Comparative Example 2 Comparative Example 3 Epoxy Resin (Ortho Cresol Novolak Resin) 13.66 13.66 13.66 Curing agent (phenol novolak resin) 6.94 6.94 6.94 Triphenylphosphine Curing Accelerator 0.24 0.24 0.24 Isocyanate Terminated Thermopolyurethane Resin 0.00 0.10 2.20 Silica 76.0 76.0 76.0 Epoxy modified silicone oil 0.13 0.13 0.13 Carbon black 0.27 0.27 0.27 Carnauba Wax 0.25 0.25 0.25 Other additives 2.51 2.41 0.31 Spiral Flow (inch) 36 34 25 Thermal strength (Shore-D) 75 74 64 Adhesion strength (kgf) 30 32 47 Glass transition temperature (℃) 154 153 141 Hygroscopicity (wt%) 0.40 0.41 0.52 Corrosion frequency 5/50 2/50 1/50 Formability (number of sticking occurrences) 0/50 1/50 12/50

[Property evaluation method]

1) Spiral Flow

: Mold was manufactured based on EMMI standard and flow length was evaluated under molding condition of 175 ℃ and molding pressure of 70kgf / cm2.

2) thermal strength

: It evaluated by Shore-D method.

3) Attachment strength

: Tensile force (UTM) between the lead frame (alloy 42) and the epoxy encapsulant was evaluated.

4) glass transition temperature

: After the test piece was produced using the bending test mold, it was measured by post-curing at 175 ° C. for 6 hours.

5) moisture absorption rate

: A test piece was prepared using a bending test mold and post-cured at 175 ° C. for 5 hours, followed by moisture absorption at 24 ° C. under a pressure cooker tester (PCT) at 120 ° C./100% RH for 24 hours. The moisture absorption rate was evaluated.

6) corrosion occurrence

: 20 SOP (small outline package) was molded and post-cured, and then absorbed for 168 hours under constant temperature and humidity conditions of 85 ° C / 65% RH, followed by three passes of IR reflow for 10 seconds at 245 ° C. Pretreatment. Subsequently, PCT was absorbed for 168 hours under constant temperature and humidity conditions of 121 ° C / 100% RH, and then the degree of corrosion of the aluminum pad was evaluated.

7) formability

: 20 SOPs were molded to evaluate the number of sticking occurrences.

As can be seen from Table 1, when the semiconductor element is sealed using the epoxy resin composition according to Examples 1 to 3, since the adhesion between the resin composition and the lead frame is greatly improved, moisture penetration into the semiconductor element is suppressed. Also, aluminum pad corrosion is prevented and formability is excellent.

On the other hand, as can be seen from Table 2, when the isocyanate-terminated thermopolyurethane resin is not added at all or when added to 0.20% by weight or less of the total epoxy resin composition as in Comparative Examples 1 to 2, the adhesion between the resin composition and the lead frame is enhanced. On the other hand, when added at more than 2.00% by weight as in Comparative Example 3, the adhesion improvement reaches saturation level, but the moisture absorption rate rapidly increases, the thermal strength decreases, and the sticking during molding ( Many working problems are found, including many stickings, and even chip corrosion.

As described in detail above, the epoxy resin composition for sealing a semiconductor device of the present invention has excellent workability during molding and excellent resistance to corrosion of the aluminum pad even under high temperature and high humidity conditions. The defect can be solved.

Claims (5)

An epoxy resin composition for sealing semiconductor elements comprising an ortho cresol novolac epoxy resin, a curing agent, a curing accelerator, a modified silicone oil, and an inorganic filler, wherein an isocyanate-terminated thermopolyurethane resin is added. Epoxy resin composition. The method of claim 1, (1) 9.00 to 15.00 wt% of ortho cresol novolac epoxy resin of the following formula (1), (2) 5.00 to 10.00% by weight of one or two or more curing agents selected from the group consisting of phenol novolac resins, cresol novolac resins and dicyclopentadiene resins having two or more hydroxyl groups and a hydroxyl equivalent of 100 to 200; , (3) 0.01 to 0.40% by weight of triphenylphosphine-based curing accelerator, (4) 0.10 to 0.20% by weight of modified silicone oil, (5) 75.00-85.00 wt% of inorganic fillers and (6) isocyanate terminal with molecular weight 3000-20000 Thermopolyurethane resin 0.20 ~ 2.00 wt% Epoxy resin composition for sealing semiconductor elements comprising a. [Formula 1] Where n is 0, 1 or 2 The method of claim 2, Epoxy resin composition for sealing a semiconductor device, characterized in that the content of the phenol novolak resin of the formula (2) in the curing agent mixture is 50% by weight or more. [Formula 2] Where n is 0, 1 or 2 The method of claim 2, The triphenyl phosphine-based curing accelerator has a structure of the formula (3) below epoxy resin composition for semiconductor element sealing. [Formula 3] The method of claim 2, The inorganic filler is an epoxy resin composition for semiconductor element sealing, characterized in that the average particle size is 0.1 ~ 35.0㎛ and the fused silica of the composition ratio of the crushing type and the spherical shape of 2 to 8 to 8 to 2.