JPH07165875A - Resin composition - Google Patents

Abstract

PURPOSE:To obtain a resin compsn. which gives a good YAG laser marking and is effective in process shortening and cost reduction. CONSTITUTION:A resin compsn. comprises an epoxy resin, a curing agent, an inorg. filler, an accelerator, 0.2-1.0wt.% (based on the total compsn.) carbon black having an average particle size of 50nm or higher, and 0.01-1.0wt.% (based on the total compsn.) antioxidant.

Description

Detailed Description of the Invention

FIELD OF THE INVENTION The present invention relates to a semiconductor encapsulating resin composition excellent in YAG laser marking property.

[0002]

2. Description of the Related Art Conventionally, a plastic-sealed semiconductor device has been marked with a special ink of thermosetting or UV-curing type. However, it takes time for marking and curing, and the handling of the ink is not easy. For this reason, the number of electronic component manufacturers that use laser marks is increasing recently. Printing on the surface of epoxy resin molded products by irradiation with YAG or CO ₂ laser light for a short time is superior to ink marking in workability and is a method that ends in a short time, which is an advantage for electronic component manufacturers. There are many methods. However, when laser-marking the surface of an encapsulation molded product of a semiconductor device encapsulated with a conventional encapsulating resin composition, the contrast between the marked part and the unmarked part is unclear, and the marking is yellow. Therefore, it is difficult to read the print. Regarding CO ₂ laser marks, effective colorants have already been developed, and resin compositions for semiconductor encapsulation that provide clear printing have been put on the market, but regarding YAG laser marks, they are effective for YAG laser mark properties. Various carbon blacks have been studied. For example, according to JP-A-2-127449, "carbon black having a carbon content of 99.5% by weight or more and a hydrogen content of 0.3% by weight or less" is said to be effective for the same purpose. There is. However, the marking contrast after volatilization of carbon black is not yet sufficient, clear printing has not been obtained, and a resin composition for semiconductor encapsulation having excellent laser mark properties is required.

[0003]

DISCLOSURE OF THE INVENTION The present inventor has studied the mechanism of laser marking property, and further traces back to the individual raw materials of the encapsulating resin composition, and as a result, has found that the average particle diameter is 50 nm. The present invention was found to be extremely effective in improving the contrast of the YAG laser mark by using the above carbon black and an antioxidant together.

[0004]

That is, the present invention provides (A)
Epoxy resin, (B) curing agent, (C) inorganic filler,
(D) a curing accelerator and (E) carbon black having an average particle size of 50 nm or more and an antioxidant are essential components, and carbon black is 0.2 to 0.2% in 100% by weight of the total composition.
It is an epoxy resin composition for semiconductor encapsulation containing 1.0% by weight and 0.01 to 1.0% by weight of an antioxidant, and this cured product exhibits excellent laser marking properties, and clear marking can be obtained. .

Each composition will be described below. The epoxy resin used in the present invention is not particularly limited as long as it has two or more epoxy groups in the molecule. For example, orthocresol novolac type epoxy resin, phenol novolac type epoxy resin, bisphenol type epoxy resin, naphthalene. Type epoxy resin, triphenol methane type epoxy resin, triazine nucleus-containing epoxy resin, biphenyl type bifunctional epoxy compound and modified resins thereof. In order to improve the moisture resistance of the resin composition, it is desirable that impurity ions such as Cl ions and Na ions as impurities are as small as possible, and the epoxy equivalent is preferably 150 to 300 g / eq from the viewpoint of curability. The curing agent is not particularly limited as long as it has a phenolic hydroxyl group in the molecule, and examples thereof include phenol novolac resin, paraxylylene modified phenol resin, triphenol methane resin and modified resins thereof. From the viewpoint of curability, the hydroxyl equivalent is 80 to 25.
0 g / eq is desirable. As the inorganic filler, fused silica powder, spherical silica powder, crystalline silica powder, alumina and the like can be used, but a mixture of fused silica powder and spherical silica powder is particularly desirable. Further, in order to obtain good laser markability, it is desirable to increase the compounding amount of the inorganic filler in the resin composition. However, regarding this compounding amount, there is concern about moldability failure due to deterioration of fluidity, so that the required characteristics It is used by appropriately selecting and adjusting it. The curing accelerator is
Any material that promotes the reaction between the epoxy group and the hydroxyl group may be used, and those generally used for sealing resins can be used. For example, there are 1,8-diazabicycloundecene, triphenylphosphine, benzyldimethylamine, 2-methylimidazole and the like, which may be used alone or in combination.

The carbon black and the antioxidant used in the present invention are the key to improving the laser mark property of the resin molded product, and are important technical points. First, the mechanism of the YAG laser mark will be briefly described. The wavelength of a YAG (yttrium, aluminum, gallium) laser is 1.06 μm, and an organic compound having a light absorption band of a wavelength of 1.06 μm converts laser energy into heat when irradiated with a YAG laser. Fever → combustion →
The surface is burned off through the process of evaporation. Carbon black has an absorption band of 1.06 μm, but there is no absorption band for epoxy resin / hardening agent / silica filler / others, and only carbon black is burned / vaporized by irradiation of YAG laser, and carbon black is removed later. Since the resin composition is exposed and the color of the exposed surface is whitish, white printing is obtained. That is, it is necessary to develop carbon black that absorbs the energy of the YAG laser and burns / evaporates quickly.

The first technical point in the present invention is special carbon black. The carbon black used in the present invention has an average particle size of 50 nm.
It must be above. If the particle size is less than 50 nm, the contrast between the marked portion and the non-marked portion is insufficient and only unclear marking can be obtained. Especially the printing itself is dark, carbon black is YAG
It was confirmed that the material was not sufficiently burned / evaporated even by laser irradiation. Therefore, by using carbon black having an average particle size of 50 nm or more, the darkness of the printing itself disappeared and the marking contrast could be greatly improved. It is presumed that the carbon black became easier to burn / evaporate due to the larger particle size of the carbon black.

When the average particle size is larger than 150 nm, the YAG laser mark property is not a problem, but the formed product itself has a low degree of coloring, and even if the carbon black content is increased to some extent, a grayish black form is formed. It is desirable to use carbon black having an average particle diameter of 150 nm or less because it becomes a product and has a problem in practical use. Further, the carbon black used in the present invention needs to be contained in an amount of 0.2 to 1.0% by weight based on 100% by weight of the total composition. 0.15 to 0.3 for conventional small particle size carbon black
Although a sufficiently black molded product was obtained at about 10% by weight, the carbon black used in the present invention needs to be added in a slightly large amount. This is because as the particle size of carbon black increases, the coloring power decreases, and the originally black color of the molded product becomes grayish black . If it is not blended in an amount of 0.2% by weight or more, the contrast itself of the laser mark is lowered. If it exceeds 1% by weight, the carbon black is not sufficiently removed even by the irradiation of laser light, the printing becomes black, and the effect of the present invention decreases. The carbon black to be used is not particularly limited as long as it has the above-mentioned characteristics, but it is preferably powder in order to be uniformly dispersed in the resin composition. Further, even if these particles are granulated, there is no particular problem as long as they are in a shape that can be easily loosened.

A second technical point of the present invention is to use an antioxidant together. In order to obtain a white print, the surface of the resin composition molded product when the carbon black is removed needs to be white, but in the conventional molded product, this portion is oxidized and colored yellow after post-cure. Therefore, to improve the contrast of printing,
Although only carbon black can be improved, the printing itself becomes yellow, and white beautiful printing cannot be obtained.
Therefore, it is necessary to whiten the color of the resin composition molded product after removing the carbon black. In order to make the color of the molded product white, it is conceivable to add a white colorant such as titanium white. However, when a white colorant such as titanium white was examined, the color of the molded product using the encapsulating resin that did not contain colored carbon black was white immediately after molding, but after post-cure the same as when titanium white was added. The resin composition was colored yellow and the YAG laser mark property of the resin composition containing carbon black was not good.

As a result of earnest studies on these problems,
It has been found that by adding a small amount of the antioxidant, the color of the molded product when carbonless is whitened, and also in the molded product containing carbon black, the YAG laser mark portion is whitened and the contrast is improved.
Among the raw materials for the semiconductor encapsulating resin composition, the raw material that is most susceptible to oxidative deterioration is phenol resin. It is considered that the surface of the molded product is colored due to oxidative deterioration of the unreacted phenol resin slightly remaining on the surface of the molded product after the curing reaction of the sealing resin composition. Therefore, when an antioxidant is added to prevent the oxidative deterioration of the surface of the molded product, the oxidative coloring of the surface of the molded product is suppressed, and the above-described favorable effects were confirmed. By combining this technology and the above-mentioned carbon black with a large particle size, excellent YAG that has never been seen before.
We have found an epoxy resin composition for semiconductor encapsulation having laser marking properties. The antioxidant used in the present invention is not particularly limited as long as it is a compound that prevents oxidative deterioration of the epoxy resin / phenolic resin, but it is in powder form for uniform dispersion in the resin composition. A structure with few ionic impurities is desirable.

Typical examples are phenol antioxidants such as 2,6-di-t-butyl-p-cresol and butylated hydroxyanisole (BHA), 2,2'-methylene-bis-(- 4-methyl-6-t-butylphenol) and other bisphenol-based antioxidants, triphenyl phosphite, 10-decyloxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene and other phosphorus-based oxidation Examples include antioxidants and sulfur-based antioxidants such as distearyl thiodipropionate. Further, the antioxidant used in the product of the present invention is 100% by weight of the total composition,
It is characterized by containing 0.01 to 1.0% by weight. 0.0
If it is less than 1% by weight, the effect of preventing oxidation is insufficient, the whitening of the laser mark is not sufficient, and the printing becomes yellow. On the other hand, if it is more than 1.0 part by weight, the moisture resistance reliability decreases.

In the present invention, an epoxy resin, a curing agent, an inorganic filler, a curing accelerator, carbon black and an antioxidant are essential components. In addition to these, a silane coupling agent, antimony trioxide, and Flame retardants such as hexabromobenzene, release agents such as natural wax and synthetic wax, and various additives such as low stress additives such as silicone oil and rubber may be appropriately blended. Further, in order to produce the encapsulating resin composition of the present invention as a molding material, an epoxy resin, a curing agent, an inorganic filler, a curing accelerator, carbon black, an antioxidant, and other additives are sufficiently mixed with a mixer or the like. After uniform mixing, the mixture can be melt-kneaded with a hot roll or a kneader, cooled, and then pulverized to obtain a sealing material.

EXAMPLES The present invention will be specifically described below with reference to examples. Example 1 Composition below Orthocresol novolac epoxy resin (softening point 65 ° C., epoxy equivalent 200) 18 parts by weight Phenols novolac resin curing agent (softening point 100 ° C., hydroxyl equivalent 100) 9 parts by weight fused silica powder 70 parts by weight Tri Phenylphosphine 0.3 parts by weight Carnauba wax 0.3 parts by weight Silicone oil 2.4 parts by weight Carbon black A (average particle size 60 nm) 0.35 parts by weight 2,6-di-t-butyl-p-cresol 0.05 part by weight was mixed at room temperature with a mixer, kneaded with a twin-screw roll at 70 to 100 ° C., cooled and pulverized to obtain a molding material. The obtained molding material was tabletted, and molded by a low-pressure transfer molding machine under the conditions of 175 ° C., 70 kg / mm ² , 120 seconds, and further as post-mold cure at 175 ° C.
A treatment was performed for 8 hours to obtain a molded product. A YAG laser mark test and a solder moisture resistance test were performed on the obtained molded product under the following conditions.

YAG laser mark conditions: Laser marker: manufactured by NEC, pulse type Wavelength: 1.06 μm Laser power: 2.0 kV Pulse width: 120 μsec YAG laser mark evaluation method: Visually check the contrast and whiteness of the print. Solder moisture resistance test A test element (16pSOP) was treated at 85 ° C / 85% RH for 72 hours, then immersed in a solder bath at 260 ° C for 10 seconds, and then a pressure cooker test (125 ° C, 100% RH) was performed. The time when the open failure occurs is shown. The evaluation results are shown in Table 1. Examples 2 to 4 Compounding was performed according to the formulation shown in Table 1, molding materials were obtained in the same manner as in Example 1, and evaluated in the same manner. The evaluation results are shown in Table 1. Comparative Examples 1 to 6 Compounding was performed according to the formulation shown in Table 2, and a molding material was obtained in the same manner as in Example 1 and evaluated in the same manner. The evaluation results are shown in Table 2.

[0015]

[Table 1]

[0016]

[Table 2]

[0017]

EFFECTS OF THE INVENTION According to the present invention, a resin composition having a good YAG laser mark property in which the YAG laser mark printing which is not obtained in the prior art is white and the contrast is clear is obtained. When this resin composition is used for encapsulation of electric and electronic parts, good printing with YAG laser marks can be obtained at high speed, which is very effective in shortening the process and cost.

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Claims (2)

[Claims] 1. An epoxy resin (A), a curing agent (B),
(C) an inorganic filler, (D) a curing accelerator, and (E) carbon black having an average particle size of 50 nm or more and an antioxidant are essential components, and 100% by weight of the total composition contains 0. 2 to 1.0 wt%, antioxidant 0.0
An epoxy resin composition for semiconductor encapsulation containing 1 to 1.0% by weight. 2. The maximum average particle size of carbon black is 15
The epoxy resin composition for semiconductor encapsulation according to claim 1, which has a thickness of 0 μm or less.