JP2002134529A - Insulating paste and optical semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulating paste and an optical semiconductor device excellent in the ultraviolet-ray-resistance and weather resistance while reliable in outdoor use and device junction around the optical semiconductor element. SOLUTION: The insulating paste is provided which comprises organic binder, solvent and/or monomer, and insulating powder. A molecule comprises at least one benzotriazole skeleton while comprising a compound which comprises methacryloyl group or hydroxyethyl group as a functional group, for example a compound represented by formula I, by 0.1-10 wt.% to a solid resin. It may be also effective that the compound is copolymerized with a monomer reacting with the functional group such as methyl methacrylate in advance before comprising, or the entire insulating powder comprises titanium oxide powder by 8-35 wt.% as a part of the insulating powder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention particularly relates to an insulating paste used for mounting an optical semiconductor element with a resin and an optical semiconductor device obtained by mounting the optical semiconductor element with a resin. The advantage is that the deterioration is small.

[0002]

2. Description of the Related Art Optical semiconductor devices, such as light emitting diodes (LEDs), which are put into practical use for various displays, etc., include an optical semiconductor element on a metal thin plate (lead frame), a metal dish, or a predetermined portion on a resin substrate. Is bonded with an insulating paste or the like, and then sealed with a transparent sealing resin or the like. The step of connecting the semiconductor element is one of the important steps that affect the long-term reliability of the element, particularly the VF characteristic and the luminance degradation of the LED.

[0003]

As electronic devices have become lighter, thinner and smaller in recent years, they have often been installed outdoors and used, and accordingly, optical semiconductor devices used in electronic devices have been required to be weatherproof. Sexuality has been strongly demanded. In addition, the development of an optical semiconductor device (blue LED) having an emission wavelength of about 450 to 500 nm requires that organic materials used in the assembly process and around the optical semiconductor device have stronger UV resistance than ever before. It became so. In particular, if the insulating paste that electrically joins the optical semiconductor element and the base material is deteriorated by ultraviolet rays, interface cracks and peeling occur due to heat shock and the like, which causes poor VF characteristics and electrical opening. In addition, since the light reflectance is reduced due to the discoloration of the cured insulating paste surface due to the deterioration of ultraviolet rays, the luminance is significantly deteriorated.

However, most of the conventional insulating pastes are based on ordinary epoxy resins,
The weather resistance was poor. In order to improve the weather resistance, an alicyclic epoxy resin or a hydrogenated epoxy resin may be used.However, since these have poor reactivity with an amine-based or phenol-based curing agent, an acid anhydride-based curing agent is used. Will use. In this case, the pot life is shortened with the one-pack type compounding, and there is a problem in workability. In addition, the cured product of the alicyclic epoxy resin is often brittle, and it is difficult for a semiconductor element having a small adhesive area to have sufficient adhesive strength, and there is a concern that cracks may occur.

On the other hand, acrylic or polyurethane resins, which have better weather resistance than epoxy resins, have low heat resistance, so that chip peeling due to heat history during the assembly process and the mounting process may become a problem. it was high. Therefore, there has been a strong demand for the development of an optical semiconductor device using an insulating paste having high UV resistance and weather resistance with the aim of improving the physical and electrical bonding reliability.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a highly reliable insulating paste and an optical paste having excellent ultraviolet resistance and weather resistance without deteriorating various performances of a conventional optical semiconductor device. It is intended to provide a semiconductor device.

[0007]

The inventor of the present invention has made intensive studies to achieve the above object, and as a result, has found that the above object can be achieved by using an insulating paste having a composition described later. The invention has been completed.

That is, the present invention relates to an insulating paste comprising at least an organic binder, a solvent or / and a monomer, and an insulating powder, comprising at least one benzotriazole skeleton in a molecule and having a methacryloyl group or a hydroxyethyl group as a functional group. An insulating paste containing a compound having a group in a ratio of 0.1 to 10% by weight based on a resin solid content. Further, an insulating paste comprising a compound containing one or more benzotriazole skeletons in the molecule and having a methacryloyl group or a hydroxyethyl group as a functional group, which is previously copolymerized with a monomer that reacts with these functional groups, and contained. And an insulating paste in which titanium oxide powder is contained as a part of the insulating powder in a proportion of 8 to 35% by weight based on the whole of the insulating powder. And it is an optical semiconductor device manufactured using these insulating pastes.

Hereinafter, the present invention will be described in detail.

The organic binder used in the present invention includes:
The type is not particularly limited, and may be a thermosetting type or a thermoplastic type, and conventionally known epoxy type, phenol type, melamine type, cellulose type, acrylic type, polyimide type and a mixed modified resin type thereof and the like. Used.
The modified resin may be simply dissolved and mixed, or may be partially bound by a heat reaction. If necessary for the reaction, a curing catalyst can be used.

With an organic binder having low heat resistance, a cured insulating paste film deteriorates under high-temperature and high-humidity conditions such as a pressure cooker test at 121 ° C. and 2 atm. Therefore, when reliability under such severe conditions is required, it is necessary to select a binder having high heat resistance. For example, a system in which a polyimide-modified resin or a novolak epoxy resin having an average number of epoxy groups of 3 or more is cured with a phenol resin may be used.

In order to improve the weather resistance of the cured paste, an alicyclic epoxy resin, a hydrogenated epoxy resin, an acrylic resin, a polyurethane resin, or the like may be used alone or as the above-mentioned resin as an organic binder having strong weather resistance. It is even more preferable to use a mixture of two or more of these. In this case, it is necessary to adjust the heat resistance and moisture resistance of the cured product according to the required characteristics.

It is desirable that these resins are dissolved and mixed with a solvent or a monomer before the paste is manufactured. As the solvent used here, those capable of dissolving these resins, for example, dioxane, hexane, toluene, methyl cellosolve, cyclohexane, butyl cellosolve, butyl cellosolve acetate,
Butyl carbitol acetate, diethylene glycol dimethyl ether, diacetone alcohol, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, γ-butyrolactone, 1,3-dimethyl-2-imidazolidinone, and the like, and these may be used alone or in combination of two or more. It can be mixed and used. Further, as the monomer, n-butyl glycidyl ether, allyl glycidyl ether, 2-ethylhexyl glycidyl ether,
Styrene oxide, phenyl glycidyl ether, cresyl glycidyl ether, p-sec-butylphenyl glycidyl ether, glycidyl methacrylate, t
-Butylphenyl glycidyl ether, diglycidyl ether, (poly) ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, butanediol diglycidyl ether, trimethylolpropane triglycidyl ether, 1,6-hexanediol glycidyl ether, etc. And these can be used alone or in combination of two or more. Further, a mixture of a solvent and a monomer can be used. When a solvent is used, it is necessary to carefully consider the boiling point and select a solvent in accordance with conditions such as a curing temperature and a curing time.

As the insulating powder used in the present invention, for example, carbon random, boron carbide, aluminum nitride,
Non-oxides such as titanium nitride, ceramic powders, and oxide powders such as beryllium, magnesium, aluminum, titanium, and silicon (specific examples include crystalline silica, fused silica, finely divided silica, and talc). A mixture of more than one species can be used. The mixing ratio of these insulating powders is not particularly limited. Further, it is desirable that the insulating powder has an average particle size of 10 μm or less. If the average particle size exceeds 10 μm, the properties of the composition do not become a paste, and the coating performance is undesirably reduced.

The compound having a benzotriazole skeleton used in the present invention acts as an ultraviolet absorber. Conventional low-molecular ultraviolet absorbers have poor compatibility with resin, so bleeding reduces the number of parts added, loss due to evaporation during heating, and low solubility of the ultraviolet absorber. Due to problems such as limitation of the number of added parts and elution into hot water, acids, alkalis, alcohols, and oils, the inherent properties of the ultraviolet absorber could not be sufficiently exhibited.

Therefore, in order to solve such a problem and enhance the effect of absorbing ultraviolet light, it is preferable to use a reactive polymer type ultraviolet absorber rather than the conventional low molecular type. Specifically, a methacryloyl group is introduced as a functional group into a benzotriazole skeleton,
-(2'-hydroxy-5'methacryloxyethylphenyl) -2H-benzotriazole (Otsuka Chemical Co., Ltd.)
Company name, product name),

Embedded image A compound having a hydroxyethyl group introduced into the functional group and represented by the following formula (trade name, manufactured by Otsuka Chemical Co., Ltd.)

Embedded image Is mentioned.

Further, a high molecular type ultraviolet absorber may be added as it is, but when the functional group has poor reactivity with the base resin, a copolymer is prepared from a monomer which reacts with the functional group in advance. Even if it is blended, the same effect can be obtained.

The compounding ratio of the compound containing at least one benzotriazole skeleton in the molecule and having a methacryloyl group or a hydroxyethyl group as a functional group is preferably 0.1 to 10% by weight based on the resin solid content. . If the amount is less than 0.1% by weight, the effect of suppressing the deterioration of the resin due to ultraviolet rays is lost. On the other hand, when the content exceeds 10% by weight, the cured product characteristics of the paste are deteriorated, and hence the paste lacks reliability and is not preferable.

The average particle size of the titanium oxide powder used in the present invention is desirably 5 μm or less. If it exceeds 5 μm, the properties of the paste and workability deteriorate, and the surface of the coating film of the cured product becomes rough. The range of the compounding amount is 8 to 35% by weight, particularly preferably 15 to 25% by weight, based on the whole insulating powder containing titanium oxide in the insulating paste. When the amount of the titanium oxide powder is less than 8% by weight, the effect of preventing ultraviolet rays is reduced. , Lacks performance as a paint or adhesive. Further, titanium oxide generally has a rutile type and an anatase type as a crystal form used as a pigment, but in order to improve ultraviolet resistance, it is preferable to use a rutile type having a large ultraviolet absorption amount. These can be used alone or in combination of two or more.

The insulating paste used in the present invention is the above-mentioned modified resin, solvent monomer or a mixture thereof, and insulating powder, and contains a specific ultraviolet absorber and titanium oxide as essential components. A curing catalyst, an antifoaming agent, a coupling agent, and other additives can be blended as long as the purpose is not adversely affected. This insulating paste can be produced by sufficiently mixing the above-described components according to a conventional method, and further performing a kneading treatment using, for example, a disperser, a kneader, a three-roll mill, or the like, and then defoaming under reduced pressure. The insulating paste thus produced is filled in a syringe, discharged onto a base material such as a lead frame using a dispenser, bonded to the optical semiconductor element by mount curing, wire-bonded, and then sealed with a transparent sealing resin. An optical semiconductor device can be manufactured by sealing and curing.

[0021]

According to the present invention, a specific ultraviolet absorbing agent is used to prevent the insulating paste for bonding an optical semiconductor element and a base material from ultraviolet rays.
In addition, by increasing the specific amount of titanium oxide, compared to conventional optical semiconductor devices, the decrease in adhesion at the joints under UV exposure is suppressed, and the gloss and light reflectance of the cured paste surface are maintained. , Improvement of electrical reliability of optical semiconductor devices,
This realizes reduction in luminance degradation.

That is, a benzotriazole-based UV absorber having a terminal acrylic group or a hydroxyethyl group as a functional group is introduced into the insulating paste, and the UV absorber and the base resin are reacted, or the terminal acrylic By adding the group as a high molecular weight polymer previously copolymerized with methyl methacrylate or styrene monomer, dispersibility with resin, which is a drawback of conventional ultraviolet absorber,
Bleed-out, heat loss during curing, etc.
The purpose was achieved by enhancing the effect of preventing ultraviolet rays. In addition, by using a titanium oxide powder having an ultraviolet absorbing effect in combination with the insulating paste, the ultraviolet absorbing effect can be further enhanced.

By this method, the conventional heat resistance and the conventional heat resistance can be obtained without considering the weather resistance of the resin serving as the base of the insulating paste.
An optical semiconductor device excellent in weather resistance and ultraviolet resistance in addition to characteristics such as moisture resistance can be obtained.

[0024]

Next, the present invention will be described with reference to examples, but the present invention is not limited to these examples. In the following Examples and Comparative Examples, “parts” means “parts by weight” unless otherwise specified.

EXAMPLE 1 EOCN103, a cresol novolak type epoxy resin
S (manufactured by Dainippon Ink and Chemicals, Inc., 80 parts), Epicoat # 1007 of bisphenol A type epoxy resin
For 20 parts (product name, manufactured by Yuka Shell Epoxy Co., Ltd.), 40 parts of a phenolic resin BRG558 (product name, manufactured by Showa Polymer Co., Ltd.) as a curing agent was dissolved in 140 parts of diethylene glycol diethyl ether at 85 ° C. for 1 hour. Do
A viscous resin was obtained. To 28 parts of the resin, 0.2 part of imidazole 2-ethyl-4-methylimidazole as a curing catalyst, 0.8 part of an additive, 28 parts of spherical fused silica powder (average particle diameter of 6 μm), and 1 part of average particle diameter of 1 μm 5 parts of rutile-type titanium oxide powder and 1 part of the above-mentioned compound of the formula (2) were mixed, kneaded with a three-roll mill, and defoamed under reduced pressure to produce an insulating paste of Example 1.

Example 2 5.5 parts of YL983U epoxy resin (trade name, manufactured by Yuka Shell Epoxy Co., Ltd.) and 2021 of celoxide, alicyclic epoxy resin (trade name, manufactured by Daicel Chemical Industries, Ltd.) 7
Parts, GT302 (manufactured by Daicel Chemical Industries, Ltd., trade name) 2 parts of the same resin, 3.5 parts of polypropylene glycol glycidyl ether, 0.3 part of cationic catalyst SI-80L (manufactured by Sanshin Chemical Co., Ltd.), 0.7 parts of additive, 18 parts of spherical fused silica powder (average particle size: 6 μm), average particle size: 1 μm
4 parts of rutile-type titanium oxide powder and 3 parts of a copolymer represented by the following formula were mixed, kneaded with a three-roll mill, and defoamed under reduced pressure to produce an insulating paste of Example 2. . The copolymer of Chemical Formula 3 is a copolymer of 70 parts of the compound of Chemical Formula 2 and 30 parts of methyl methacrylate.

[0027]

Embedded image (Wherein, m and n represent integers of 1 or more) Comparative Example In the formulation of Example 1, the same procedure as in Example 1 was carried out except that the rutile-type titanium oxide powder and the compound of Chemical Formula 2 were not blended. Thus, an insulating paste of a comparative example was manufactured.

Using the insulating pastes obtained in Examples 1 and 2 and Comparative Example, a lead frame and a 0.3 mm × 0.3
mm GaN-based optical semiconductor device (blue LED chip) is mounted and cured under the curing conditions shown in Table 1, wire-bonded, and then cured and sealed with an alicyclic epoxy resin-based transparent sealing material (120 ° C. × 2H + 130 ° C.) × 6H) to produce optical semiconductor devices.

These optical semiconductor devices were subjected to an adhesive strength under ultraviolet irradiation, a normal temperature energization test, and a high temperature and high humidity storage test. The results are shown in Table 1. The present invention was excellent in each case, and the remarkable effects of the present invention were confirmed.

[0030]

[Table 1] * 1: 0.3mm × 0.3mm chip (200μ in height)
m), lead frame (copper, bed surface silver plated)
The above was adhered using an insulating paste and cured under the above-mentioned predetermined conditions. After curing, the adhesive strength in the shear direction was measured using a tension gauge. The hot adhesive strength was measured on a 250 ° C. heat block.

* 2: Sunshine weatherometer was used.

* 3: A normal-temperature current test (forward current 30) was conducted in the state where ultraviolet rays were irradiated with a sunshine weatherometer.
mA), a high-temperature and high-humidity storage test in an environment of 60 ° C. and 95% RH was evaluated for each optical semiconductor device. The number of optical semiconductor devices subjected to the energization test was 60, and the number of occurrences of defects with the passage of time was shown. In the defect determination method, a failure was determined when the luminance change rate increased to 50% or more in the initial stage.

[0033]

As is clear from the above description and Table 1, the optical semiconductor device of the present invention can be used outdoors or at an emission wavelength of 450 to 500 nm by using an insulating paste having excellent ultraviolet resistance and weather resistance. When used in the vicinity of a nearby optical semiconductor element, it is possible to improve the physical and electrical bonding reliability of the element and extend the life of the optical semiconductor device more than before, which is very useful industrially. is there.

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Claims (4)

[Claims] 1. At least an organic binder, a solvent and / or
And a monomer, and an insulating paste composed of an insulating powder, a compound containing at least one benzotriazole skeleton in the molecule and having a methacryloyl group or a hydroxyethyl group as a functional group is added in an amount of 0.1 to the resin solid content.
An insulating paste, which is contained in a proportion of 10 to 10% by weight. 2. A compound containing at least one benzotriazole skeleton in the molecule and having a methacryloyl group or a hydroxyethyl group as a functional group, which is previously copolymerized with a monomer which reacts with the functional group and contained.
The insulating paste as described. 3. The insulating paste according to claim 1, wherein titanium oxide powder is contained as a part of the insulating powder in a proportion of 8 to 35% by weight based on the whole of the insulating powder. 4. An optical semiconductor device comprising an optical semiconductor element and a base material such as a lead frame bonded and fixed using the insulating paste according to claim 1.