JP2001181481A - Epoxy resin composition for semiconductor sealing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin composition for sealing semi-conductor that has high fluidity and good filling properties as well as solder heat resistance, moisture resistance and moisture-resistant reliability. SOLUTION: This epoxy resin composition for semiconductor sealing comprises (a) an epoxy resin, (b) a curing agent for epoxy resin, (c) a curing accelerator and (e) an inorganic filler including (d) a laminar compound, as essential components, wherein the equivalent ratio of the epoxy resin (a) to the curing resin is in the range from 0.5-2.0, the amount of the curing accelerator (c) is 0.4-20 pts.wt. per 100 pts.wt., the amount of the inorganic filler is 200-2,400 pts.wt. per 100 pts.wt. of 100 pts.wt. of the total of (a) and (b) and the amount of the laminar compound in the inorganic filler is 0.1-20 pts.wt. per 100 pts.wt. of the total of the (a) and (b).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition for sealing electronic parts such as semiconductors, which has excellent solder stress resistance, moisture resistance, heat cycle property and high fluidity.

[0002]

2. Description of the Related Art Conventionally, electronic components such as diodes, transistors, and integrated circuits are sealed with a thermosetting resin. Particularly, in an integrated circuit, an o-cresol novolac epoxy having excellent heat resistance and moisture resistance is used. Or, a system composed of a biphenyl type epoxy resin and a novolak type phenol resin is often used.

In recent years, with the trend toward miniaturization, weight reduction and high performance of electronic equipment, with the integration of semiconductors, a conventional method of inserting a lead pin into a hole of a substrate has been replaced by a method of mounting a component on a substrate surface. The shift to the surface mounting method of soldering is underway. In the surface mounting method, unlike the insertion mounting method, the entire package sealed with the sealing resin is heated to a high temperature of 210 to 270 ° C. during soldering during the mounting process. For this reason, cracks occur in the resin portion, cracks and peeling occur in the vicinity of the chip, and there is a problem that the reliability is lowered and the product cannot be used.

[0004] Many hypotheses have been proposed for the mechanism of crack generation, but are generally considered as follows. The sealing resin of the package absorbs moisture during the mounting process. On the other hand, during the surface mounting operation, the entire package is exposed to a high temperature of 200 ° C. or higher, and in a thin package, the temperature inside the package also rises to 200 ° C. or higher in a short time. When the moisture-absorbed package is rapidly heated to 200 ° C. or higher, an internal pressure is generated due to vaporization of moisture, and a crack occurs when the internal pressure of the package exceeds the breaking strength of the sealing material.

Further, interfacial peeling is caused by volume shrinkage occurring when a curable resin such as an epoxy resin is cured, and thermal stress inside a package caused by a difference in linear expansion coefficient between a metal and an epoxy resin molding material. It is considered.

In order to overcome the above-mentioned drawbacks, a method of increasing the elastic modulus of the sealing resin and reducing the coefficient of linear expansion have been adopted. For example, high filling of the filler is one of them. However, although high filling of the filler is an effective means, there is a limit, and there is a problem that the viscosity of the sealing resin increases and the fluidity decreases. An increase in resin viscosity causes deformation or cutting of the lead wire, and a decrease in fluidity causes a decrease in filling property,
Reliability may be reduced.

[0007]

SUMMARY OF THE INVENTION The present invention solves such a problem of a resin for semiconductor encapsulation, and eliminates deformation and disconnection of a lead wire when encapsulating an electronic circuit component such as a semiconductor device. High fluidity, good filling, no cracks in the resin part during soldering, no cracking or peeling around the semiconductor chip, solder heat resistance, moisture resistance, moisture resistance reliability, fluidity, etc. It is an object of the present invention to provide an epoxy resin composition for semiconductor encapsulation which is excellent in the above.

[0008]

Means for Solving the Problems The inventors of the present invention have made intensive studies to achieve the above object, and as a result, a part of the inorganic filler used in the epoxy resin composition for semiconductor encapsulation has been replaced with a layered material. By replacing with an inorganic compound having a structure,
The inventor has found that the above-mentioned object can be achieved, further studied, and completed the present invention.

That is, the present invention provides an epoxy resin (a), an epoxy resin curing agent (b), a curing accelerator (c), and
The inorganic filler (e) containing the layered compound (d) is an essential component, the equivalent ratio of the epoxy resin (a) to the curing agent (b) is in the range of 0.5 to 2.0, and the curing accelerator (c) ) The amount is in the range of 0.4 to 20 parts by weight per 100 parts by weight of the total amount of the epoxy resin (a) and the curing agent (b), and the blending amount of the inorganic filler (e) is Total amount of agent (b) 1
The mixing amount of the layered compound (d) in the inorganic filler (e) is in the range of 200 to 2400 parts by weight per 100 parts by weight, and the total amount of the epoxy resin (a) and the curing agent (b) is 100
It is characterized in that it is in the range of 0.1 to 20 parts by weight per part by weight, and the layered compound (d) is a layered inorganic compound having organic molecules or organic ions between layers. And an epoxy resin composition for semiconductor encapsulation.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The epoxy resin (a) used in the present invention is not particularly limited in molecular structure, molecular weight, etc., as long as it has at least two epoxy groups in its molecule. The epoxy resin used for the application can be used as it is. Specifically, for example,
Biphenyl epoxy resin, bisphenol epoxy resin, stilbene epoxy resin, phenol novolak epoxy resin, cresol novolak epoxy resin, naphthalene epoxy resin, triphenolmethane epoxy resin, alkyl-modified triphenolmethane epoxy resin, triazine nucleus Examples thereof include a contained epoxy resin and a dicyclopentadiene-modified phenol type epoxy resin. These epoxy resins may be used alone or in combination of two or more. Among these epoxy resins,
A crystalline epoxy resin having a melting point of 50 to 150 ° C is preferred.

The epoxy resin curing agent (b) used in the present invention includes an amine curing agent, an acid anhydride curing agent,
There is no particular limitation as long as it can be cured by reacting with an epoxy resin, such as a phenolic resin. Specifically, for example, amine-based curing agents such as metaphenylenediamine, diaminodiphenylmethane, aromatic diamines such as diaminodiphenylsulfone, and acid anhydride-based curing agents such as maleic anhydride, phthalic anhydride, and pyromellitic anhydride. ,
Examples of the phenolic resin curing agent include novolak-type phenolic resins, cresol-type novolak resins, aralkyl resins such as para-xylylene- and meta-xylylene-modified phenolic resins, terpene-modified phenolic resins, dicyclopentadiene-modified phenolic resins, and triphenols. Examples include propane, but are not limited thereto. However, a phenol resin-based curing agent is preferable in view of physical properties such as water absorption, and among them, a phenol aralkyl resin is particularly preferable.

The mixing ratio of the epoxy resin (a) to the curing agent (b) is such that the equivalent ratio of the epoxy group of the epoxy resin to the curing agent is in the range of 0.5 to 2, and preferably 0.7 to 1.5. It is. If the equivalent ratio is less than 0.5 or more than 2, the moisture resistance, moldability, and electrical properties of the cured product are undesirably deteriorated.

The curing accelerator (c) is not particularly limited as long as it is a compound capable of promoting the curing reaction between the epoxy resin and the curing agent. For example, amidine compounds such as 1,8-diazabicyclo (5,4,0) undecene-7, triphenylphosphine, tetraphenylphosphonium.
Examples include organic phosphorus compounds such as tetraphenylborate and imidazole compounds such as 2-methylimidazole, but are not limited thereto. These curing accelerators may be used alone or as a mixture. The compounding amount is preferably in the range of 0.4 to 20 parts by weight per 100 parts by weight of the total amount of the epoxy resin (a) and the curing agent (b). If the amount is less than 0.4 part by weight, sufficient curability may not be obtained at the time of heat molding.
If the amount exceeds 20 parts by weight, the curing is too fast, and there is a possibility that poor filling may occur due to a decrease in fluidity during molding, which is not preferable.

The layered compound (d) used in the present invention is not particularly limited as long as it is an inorganic compound having a layered structure, and may be a layered compound having ion exchange properties and a layered compound having no ion exchange properties. And specific examples thereof include silicates, chalcogenides, metal phosphates, and the like.

Examples of the silicates include kaolinite, dickanite, and kaolin minerals such as halosite, leader site, serpentine such as antigorite, parophyllite, talc, mica clay mineral, chlorairot, vermiculite,
Examples include smectites such as montmorillonite, hiderite, nontrolite, saponite, and hectorite, sepiolite, palygorskite, and mixed layer minerals thereof, and both natural products and synthetic products can be used.

As chalcogen compounds, dichalcogenides MX2 (X is S, Se) of Group IV (Ti, Zr, Hf), Group V (V, Nb, Ta) and Group VI (Mo, W)
Alternatively, Te) and the phosphate include zirconium phosphate and the like.

Of these, preferred are silicate-based layered compounds, and more preferred are layered compounds having organic substances such as organic molecules and organic ions between layers.
By having an organic substance between the layers, the affinity with the resin is improved, and the layered compound is easily dispersed finely in the resin.

The layered silicate compound having an organic substance between layers includes a complex (a molecular complex) in which an organic compound penetrates between layers in a molecular state and an exchangeable inorganic compound existing between the layers of the layered compound. A complex (ion complex) formed by ion exchange of a cation with an organic cation is known. Examples of organic molecules include alcohols such as ethylene glycol and glycerin, higher hydrocarbons, and examples of organic cations include ammonium ions, pyridinium ions, phosphonium ions, and sulfonium ions. There is no particular limitation.

As the component other than the layered compound (d) in the inorganic filler (e), an inorganic filler generally used for a sealing material can be used. Specific examples include fused silica powder, fused spherical silica powder, crystalline silica powder, secondary aggregated silica powder, alumina, aluminum hydroxide, glass fiber, and the like, and fused spherical silica is particularly preferred. The shape of the spherical silica is preferably infinitely spherical in order to improve the fluidity, and a wider particle size distribution is more preferable.

The compounding amount of the inorganic filler (e) is preferably in the range of 200 to 2400 parts by weight per 100 parts by weight of the total of the epoxy resin (a) and the curing agent (b). If the amount is less than 200 parts by weight, the reinforcing effect of the inorganic filler may not be sufficiently exerted. If the amount exceeds 2400 parts by weight, the fluidity of the resin composition may be reduced, resulting in poor filling during molding, or deformation or disconnection of a lead wire. Is not preferred.

On the other hand, the layered compound (d) is different from the granular or spherical inorganic filler other than the layered compound, and is finely dispersed in the resin, thereby significantly increasing the elastic modulus of the cured resin even in a small amount. The coefficient of linear expansion and the water absorption can be reduced. Therefore, even if a part of the granular or spherical inorganic filler is replaced with a smaller amount of a layered compound, the properties of the layered compound finely dispersed in the encapsulant cause the physical properties of the filler to be reduced. It is possible to suppress the decrease, and it is possible to improve the fluidity by reducing the amount of the filler in the sealing material.
The compounding amount is preferably in the range of 0.1 to 20 parts by weight per 100 parts by weight of the total amount of the epoxy resin (a) and the curing agent (b). If the amount is less than 0.1 part by weight,
The effect of the layered compound is not sufficiently exhibited. On the other hand, if it exceeds 20 parts by weight, no further improvement in the effect can be expected, and it is not preferable to use the compound more than necessary from the viewpoint of cost.

The layered compound (d) used in the present invention
It is desirable that the resin be previously melt-mixed with an epoxy resin and a curing agent or a mixture of an epoxy resin and a curing agent.

In addition to the components (a) to (e), the resin composition of the present invention may contain, if necessary, a flame retardant such as a brominated epoxy resin, antimony oxide, or a phosphorus compound, or a bismuth oxide hydrate or the like. Inorganic ion exchangers, coupling agents such as γ-glycidoxypropyltrimethoxysilane, carbon black, coloring agents such as redwood, silicone oil, low stress materials such as silicone rubber, natural wax, synthetic wax,
Various additives such as release agents such as higher fatty acids and metal salts thereof or paraffin, and antioxidants may be appropriately compounded.

When the epoxy resin composition for semiconductor encapsulation of the present invention is produced as a molding material, an epoxy resin, a curing agent, a curing accelerator, a layered compound, other inorganic fillers,
And other additives are sufficiently mixed by a mixer or the like, and further melt-kneaded using a hot roll, a kneader or the like, cooled, and pulverized to obtain a molding material. In order to seal electronic components such as semiconductor elements and manufacture a semiconductor device, sealing is performed by a molding method such as transfer molding, compression molding, or injection molding.

[0025]

The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. Here, each component is blended and kneaded to prepare a molding material, and to evaluate its properties, a spiral flow, a curing torque, a residual flow rate, a strength at heat, and a water absorption rate are measured, and a test for moisture resistance reliability is performed. Was. The measuring method and conditions of each characteristic were as follows.

1. Spiral flow For the molding material immediately after preparation, EMMI-I-6
Using a mold for spiral flow measurement according to 6, the measurement was performed at a mold temperature of 175 ° C., an injection pressure of 70 kgf / cm ² , and a curing time of 2 minutes. Spiral flow (cm) is a parameter of fluidity, and a larger value means better fluidity.

2. Curing torque Using the prepared molding material, a curast meter (JSR Curast Meter PS type, manufactured by Orientec Co., Ltd.)
The torque after heating at 175 ° C. for 45 seconds was measured.
The torque value (kgf · cm) by a curast meter is a parameter of curability, and a larger value indicates higher curability.

3. After storing at 30 ° C. for 1 week, the spiral flow was measured, and the percentage of the spiral flow immediately after the preparation (%)
Ask for. The larger the value, the better the preservability.

4. Hot strength A test piece was molded in accordance with JIS-K-6911,
The flexural strength (N / mm ² ) was measured at ° C.

5. Water absorption rate Using a transfer molding machine, mold temperature 175 ° C, injection
Input pressure 75kg / cm ^Two, Curing time 2 minutes, diameter
Form a 50mm, 3mm thick disk, 8 hours at 175 ° C
After immersion in distilled water at 23 ° C for 24 hours
Then, the weight change was measured to determine the water absorption (% by weight).

6. Moisture resistance reliability Using the prepared molding material, a mold temperature of 175 ° C., an injection pressure of 70 kg / cm ² , and a curing time of 2 minutes were used to obtain 16 pD
After molding IP (monitor IC mounted with a simulated element), post-curing was performed at 175 ° C. for 8 hours to prepare a sample element. This device was tested at 125 ° C and 100% relative humidity.
A voltage of 20 V was applied in water vapor, and the time until a disconnection failure occurred was examined. The time until a failure appeared in eight or more of the 15 sample elements was defined as the failure time. In addition,
The measurement time was 500 hours at the maximum, and when the number of defective samples was less than 8 at that time, the defective time was 500 hours or more. The longer the failure time, the better the moisture resistance reliability.

Example 1 The following components were mixed, kneaded at 95 ° C. for 8 minutes using a hot roll, cooled, and pulverized to obtain a resin composition. The layered compound used was obtained by swelling the layered compound "Kunipia F" (manufactured by Kunimine Industries) in water, ion-exchanging with dodecylammonium hydrochloride, washing the precipitate, and drying. . The evaluation results were as shown in Table 1. Resin mainly composed of biphenyl type epoxy resin (epoxy equivalent: 185, melting point: 105 ° C) 51 parts by weight Phenol resin (hydroxyl equivalent: 167, softening point: 73 ° C) 49 parts by weight Triphenylphosphine 0.8 parts by weight Fused spherical silica (average) 485 parts by weight Layered compound 2.5 parts by weight Carbon black 2 parts by weight Brominated bisphenol A type epoxy resin 2 parts by weight Carnauba wax 2 parts by weight

(Examples 2 to 5) Molding materials were prepared in the same manner as in Example 1 with the respective formulations shown in Table 1. The evaluation results are summarized in Table 1.

(Comparative Examples 1 to 5) Molding materials were prepared according to the respective formulations shown in Table 2 and operated in the same manner as in Example 1, and evaluated. The evaluation results are collectively shown in Table 2.

[0035]

[Table 1]

[0036]

[Table 2]

[0037]

As is clear from the evaluation results of Examples 1 to 5, according to the present invention, a part of the granular or spherical inorganic filler is replaced with a smaller amount of a layered compound of a certain amount, and the sealing is performed. By finely dispersing in the material, an epoxy resin composition for semiconductor encapsulation can be obtained which does not deteriorate physical properties even by reducing the amount of filler, and has excellent fluidity and moldability, and a semiconductor device using the same. Has excellent crack resistance and moisture resistance.

Claims (2)

[Claims] An epoxy resin (a), a curing agent (b) for an epoxy resin, a curing accelerator (c), and an inorganic filler (e) containing a layered compound (d) are essential components. The equivalent ratio of the resin (a) to the curing agent (b) is 0.5 to 2.5.
0, the amount of the curing accelerator (c) is 0.4 to 20 per 100 parts by weight of the total amount of the epoxy resin (a) and the curing agent (b).
The amount of the inorganic filler (e) is in the range of 200 to 2400 parts by weight per 100 parts by weight of the total amount of the epoxy resin (a) and the curing agent (b). Wherein the compounding amount of the layered compound (d) is 0.1 to 20 parts by weight per 100 parts by weight of the total amount of the epoxy resin (a) and the curing agent (b). Epoxy resin composition for sealing. 2. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the layered compound (d) is a layered inorganic compound having organic molecules or organic ions between layers.