JP3357235B2 - Epoxy resin composition for semiconductor encapsulation - Google Patents

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 semiconductor encapsulation having good marking characteristics with a YAG laser or a carbon dioxide laser.

[0002]

2. Description of the Related Art In order to protect a semiconductor body from mechanical and chemical actions, epoxy resin-based resin compositions for encapsulating a semiconductor have been developed and manufactured. Items required therefor differ depending on the structure of the semiconductor package to be sealed. For example, conventionally, the surface of a semiconductor package is printed with a product number or the like by an ink mark, but recently, the use of laser marking has been increasing in order to meet requirements for low cost and short delivery time. Compared to ink marking, laser marking is said to have the following features. The advantages are
Since it can be marked in seconds, it is faster and cheaper than an ink mark that requires several hours for post-curing, and has less equipment trouble than an ink mark. On the other hand, there are disadvantages in that the contrast of printing is low, and there is a high possibility that a problem of soot removal generated during printing occurs. Therefore, it has been desired to develop a resin composition for semiconductor encapsulation that has high printing contrast and does not generate soot during printing.

[0003]

SUMMARY OF THE INVENTION The present invention relates to an epoxy resin composition for semiconductor encapsulation having improved YAG laser or carbon dioxide laser mark characteristics which can improve the contrast of printed semiconductor packages and reduce the amount of soot. Is to provide.

[0004]

Means for Solving the Problems The present invention has been studied diligently in order to achieve the above-mentioned object, and by adding a small amount of mica, it is also effective in improving the laser mark characteristics of the epoxy resin composition for semiconductor encapsulation. As a result, it was found that the epoxy resin composition for semiconductor encapsulation having the following composition had excellent solder resistance and moldability.
That is, the present invention is an epoxy resin, a phenol resin curing agent,
Curing accelerator, inorganic filler, carbon black and mica having an average particle diameter of 75 μm or less (K ₂ O.3Al ₂ O ₃ .6SiO _2.
It is an epoxy resin composition for semiconductor encapsulation containing 2H ₂ O) as an essential component.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The components of each composition are described below. The epoxy resin used in the present invention refers to a compound having an epoxy group in a molecule. Examples of the used epoxy resin include an orthocresol novolak type epoxy resin, a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, and a triphenolmethane type. Epoxy resins, naphthalene type epoxy resins, biphenyl type epoxy resins and the like can be mentioned. The degree of polymerization and epoxy equivalent of these epoxy resins are not particularly limited. However, in the case of a resin composition for encapsulating a semiconductor for surface mounting, it is required to increase the amount of the inorganic filler compounded, so that an epoxy resin having a viscosity as low as possible upon melting is desired. Further, in order to improve the moisture resistance reliability, it is desirable that chlorine ions, sodium ions and other free ions contained in these epoxy resins are as small as possible.

[0006] The phenolic resin curing agent used in the present invention refers to a compound containing a phenolic hydroxyl group in the molecule, and examples thereof include a phenol novolak resin,
Examples include paraxylylene-modified phenol novolak resin, triphenolmethane-type phenol novolak resin, and bisphenol A-type novolak resin. These curing agents may be modified with silicone or the like. Further, the hydroxyl equivalent, the degree of polymerization and the like are not particularly limited. As with the epoxy resin, a curing agent having a relatively low viscosity tends to be desirable for a resin composition for semiconductor encapsulation used for surface mounting. Also,
In order to improve the moisture resistance reliability of these resins, it is desirable that chlorine ions, sodium ions, and other free ions contained as impurities be as small as possible.

The curing accelerator used in the present invention may be any one which promotes a chemical reaction between an epoxy group and a phenolic hydroxyl group. For example, 1,8-diazabicyclo (5,4,0) Undecene-7, 2-methylimidazole, triphenylphosphine, tetraphenylphosphine / tetraphenylborate and the like. In the case of a formulation containing a low-viscosity epoxy resin and a curing agent, the hardness after molding is low unless the reactivity of the curing accelerator is high,
Since mold release failure occurs, it is more desirable to select the type and amount of the curing accelerator that can sufficiently promote the curing reaction under the molding conditions.

The inorganic filler used in the present invention includes:
Fused silica powder, spherical silica powder, crystalline silica powder, 2
Sub-agglomerated silica powder, alumina and the like are mentioned, and in particular, spherical silica powder is desirable from the viewpoint of improving the fluidity of the resin composition for semiconductor encapsulation. Regarding the shape of the spherical silica powder, in order to improve the fluidity, it is desirable that the shape of the particles themselves be infinitely spherical and that the particle size distribution be broad. The inorganic filler may be previously surface-treated with a silane coupling agent described later or another silane-based, titanium-based, or other surface treatment agent. The amount of the inorganic filler is not limited at all. There is no particular limitation on the average and maximum particle size.

The carbon black used in the present invention is:
The primary particles have an average particle size of 5 to 150 nm. The apparent average particle size may be larger than that due to secondary aggregation. In a laser mark, how to easily remove carbon black by laser irradiation is an important point. It has been found that the larger the average particle size of the carbon black is, the easier it is to be oxidized and removed from the surface of the molded article by the heat of the laser, so that the average particle size of the primary particles is desirably 50 to 150 nm. It is not limited. It is more desirable that the content of ionic impurities is small from the viewpoint of moisture resistance reliability.

The mica used in the present invention is an important technical point in the present invention, and mainly has a structure represented by (K ₂ O.3Al ₂ O ₃ .6SiO ₂ .2H ₂ O). belongs to. When irradiated with laser light, mica absorbs the laser light and emits the heat energy absorbed by the irradiated part. Therefore, when mica is compounded and dispersed in the resin composition for encapsulating a semiconductor, only the irradiated surface is heated to a high temperature by laser irradiation, and the epoxy resin and carbon black in that portion are rapidly oxidized and are exposed to air. Is removed. Since the carbon black is removed, the original white color of the epoxy resin composition appears only on the irradiated surface, and the contrast is developed. Then, Y having a short wavelength and strong power
In addition to the AG laser, there is a feature that efficient printing can be performed even with a low power carbon dioxide laser.
In the case of carbon dioxide laser, there is no laser power that can oxidize and remove only carbon black itself. Many of these organic dyes are complex, such as quinone structures.
There was a tendency for the humidity resistance reliability to be adversely affected. However, the method of blending mica according to the present invention is a method capable of improving the carbon dioxide laser mark characteristics without lowering the humidity resistance reliability. In the case of thermoplastic resins (PE, PP, etc.), a method for improving the laser mark characteristics by adding this mica is well known. But,
Until now, this has not been studied by applying this to an epoxy resin, and it has not been confirmed that the laser mark characteristics are improved thereby.

The mica used in the present invention has an average particle size of 75 μm.
m or less. If the average particle diameter exceeds the above range, when it is mixed with the resin composition for semiconductor encapsulation, it may cause gate clogging at the time of molding, and it is not desirable to use it. There is no problem even if the surface of the mica is coated with any organic or inorganic compound. Furthermore, there is no problem in using the mica surface by roughening the surface to eliminate the pearly luster on the surface or improving the laser mark property. The amount of mica used is preferably 0.02 to 2% by weight based on 100% by weight of the entire resin composition for semiconductor encapsulation. When the content is less than 0.02% by weight, no laser mark characteristics are obtained. If the content is more than 2% by weight, predetermined performance cannot be exhibited due to pearly gloss, soot at the time of laser marking, and decrease in fluidity.

The composition of the present invention may contain, if necessary, a low-stress component such as a coloring agent, a brominated epoxy resin, a flame retardant such as antimony trioxide, a silane coupling agent, silicone oil, or rubber. Can be added. The epoxy resin composition of the present invention, an epoxy resin, a curing agent,
A curing accelerator, an inorganic filler and other additives are mixed at room temperature with a mixer, kneaded with a general kneader such as a roll or an extruder, cooled, and pulverized to obtain a molding material.

[0013]

The present invention will be specifically described below with reference to examples. -Example 1 The following composition: Biphenyl type epoxy resin (melting point: 107 ° C) 8.3 parts by weight Phenol aralkyl resin (polymerization degree: 3.2) 8.1 parts by weight 1.8-diazabicyclo (5,4,0) undecene- 7 0.2 parts by weight Spherical silica powder 79.5 parts by weight Carbon black (average particle diameter 18 nm) 0.3 parts by weight Mica (K ₂ O.3Al ₂ O ₃ .6SiO ₂ .2H ₂ O) (average particle diameter 15 μm) 0.5 parts by weight Carnauba wax 0.3 parts by weight Brominated phenol novolak type epoxy resin 1.0 parts by weight Antimony trioxide 1.3 parts by weight Epoxysilane coupling agent 0.5 parts by weight is mixed at room temperature with a mixer. Then, the mixture was kneaded with a biaxial roll at 100 ° C., cooled and pulverized to obtain a resin composition. After molding a semiconductor package using the obtained resin composition, YA
The properties of the G laser mark and the carbon dioxide gas laser mark were evaluated, and the results are shown in Table 1.

* Evaluation Method << YAG Laser Marking Property >> A satin-finished molded product is molded using a tablet of the prepared epoxy resin composition for semiconductor encapsulation. After post-curing at 175 ° C. for 8 hours, the surface was marked with a YAG laser. Marking was performed under the following conditions, and the contrast, fading, and soot of the printed characters were visually observed and evaluated as follows. (Conditions) Laser marker: NEC's SL476B Laser power: 2.0 kV Pulse width: 150 μsec << Carbon dioxide laser markability >> Molding a matte product using a tablet of the prepared epoxy resin composition for semiconductor encapsulation. I do. After post-curing at 175 ° C. for 8 hours, the surface was marked with a carbon dioxide laser mark. Marking was performed under the following conditions, and the contrast, fading, and soot of the printed characters were observed with a naked eye and evaluated as follows. (Conditions) Laser marker: Zumark 7000 manufactured by Lumonics Laser output: 4J

<< Evaluation >> * Contrast * Character blurring * Soot generation ○: Good None None △: Some defects Slightly slight Slightly poor ×: Positive

Examples 2 to 6 Compounded according to the formulation shown in Table 1, a resin composition was obtained in the same manner as in Example 1, and evaluated in the same manner. The results are shown in Table 1. Comparative Examples 1 to 5 Compounded according to the formulation in Table 2 to obtain a resin composition in the same manner as in Example 1, evaluated in the same manner, and the results are shown in Table 1. In addition, as a matter of particular concern, the composition of Comparative Example 3 had reduced fluidity and caused molding problems, and the composition of Comparative Example 4 had molding problems such as gate clogging.・ Epoxy resin, phenol resin and mica used are as follows. Biphenyl type epoxy resin (melting point 107 ° C) Orthocresol novolak type epoxy resin (degree of polymerization 4.2) Phenol aralkyl type resin (degree of polymerization 3.2) Phenol novolak type resin (degree of polymerization 4.3) Mica (K ₂ O. 3Al ₂ O ₃ .6SiO ₂ .2H ₂ O) Mica A (average particle size 15 μm) Mica B (average particle size 50 μm) Mica C (average particle size 85 μm) Mica D (average particle size 15 μm, surface roughening treatment)

Table 1 Example 1 2 3 4 5 6 blending (parts by weight) Biphenyl type epoxy resin 8.3 8.3 8.3 8.3 8.3 Orthocreso-Lunophorac type epoxy resin 10.2 Phenol aralkyl type resin 8.1 8.1 8.1 8.1 8.1 Phenol novolak type resin 6.2 1.8-Phase dicyclo (5, 4,0) Undecedene-7 0.2 0.2 0.2 0.2 0.2 0.2 Spherical silica powder 79.5 79.97 78.2 79.5 79.5 79.5 Carbon black (average particle size 18 nm) 0.3 0.3 0.3 0.3 0.3 0.3 Mica A 0.5 0.03 1.8 0.5 Mica B 0.5 Mica D 0.5 Carnauba wax 0.3 0.3 0.3 0.3 0.3 0.3 Brominated phenol-phenolic epoxy resin 1.0 1.0 1.0 1.0 1.0 1.0 Antimony trioxide 1.3 1.3 1.3 1.3 1.3 1.3 Epoxysilane coupling agent 0.5 0.5 0.5 0.5 0.5 0.5 Properties YAG laser mark properties Contrast ○ ○ ○ ○ ○ ○ Blurred characters ○ ○ ○ ○ ○ ○ Generation of soot ○ ○ ○ ○ ○ ○ CO2 laser mark Characteristic Contrast ○ ○ ○ ○ ○ ○ Blurred characters ○ ○ ○ ○ ○ ○ Generation of soot ○ ○ ○ ○ ○ ○

Table 2 Comparative Example 1 2 3 4 5 Blended (parts by weight) Biphenyl type epoxy resin 8.3 8.3 8.3 8.3 8.3 Phenol aralkyl type resin 8.1 8.1 8.1 8.1 8.1 1.8-Shiasadicyclo (5,4,0) unthecene-7 0.2 0.2 0.2 0.2 0.2 Spherical Silica powder 80.0 79.99 77.7 79.5 79.8 Carbon black (average particle size 18nm) 0.3 0.3 0.3 0.3 Mica A 0.01 2.3 0.5 Mica C 0.5 Carnauba wax 0.3 0.3 0.3 0.3 0.3 Brominated phenol-phenolic phenolic epoxy resin 1.0 1.0 1.0 1.0 1.0 Antimony trioxide 1.3 1.3 1.3 1.3 1.3 Epoxysilane coupling agent 0.5 0.5 0.5 0.5 0.5 Characteristics YAG laser mark property Contrast △ △ ○ ○ × Character fading ○ ○ ○ ○ × Soot generation △ △ △ ○ × Carbon dioxide gas laser mark contrast × × ○ ○ × Blurring of characters × × ○ ○ × Generation of soot ○ ○ △ ○ ×

[0019]

The epoxy resin composition for encapsulating a semiconductor of the present invention can produce a semiconductor package having high YAG laser or carbon dioxide gas laser mark characteristics with high printing contrast and low soot generation. Performance can be improved and production costs at semiconductor manufacturers can be reduced.

────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI H01L 23/31 (56) References JP-A-6-166802 (JP, A) JP-A-6-57101 (JP, A) Japanese Unexamined Patent Publication No. Hei 2-245055 (JP, A) Japanese Unexamined Patent Publication No. Hei 4-100820 (JP, A) Japanese Unexamined Patent Publication No. Hei 2-101761 (JP, A) Japanese Unexamined Patent Publication No. Sho 63-248821 (JP, A) JP, A) JP-A-5-331263 (JP, A) JP-A-60-47065 (JP, A) JP-A-9-111696 (JP, A) JP-A-7-286074 (JP, A) JP Hei 8-231880 (JP, A) JP-A Hei 9-12776 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 63/00-63/10 C08K 3/04 C08K 3 / 34 B41M 5/26 H01L 23/29

Claims (2)

(57) [Claims] An epoxy resin, a phenol resin curing agent,
An epoxy resin composition for semiconductor encapsulation, comprising a curing accelerator, an inorganic filler, carbon black, and mica having an average particle size of 75 μm or less as essential components. 2. The main component of mica is K ₂ O.3Al ₂ O ₃ .6.
The epoxy resin composition for semiconductor encapsulation of claim 1 having a structure of SiO ₂ · 2H ₂ O.