JPH10135522A - Light emitting diode device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a sealing layer which is excellent in light permeability and humidity resistance by sealing a light emitting diode element with epoxy resin which contains sulfonium slat shown in a general formula as a hardening catalyst. SOLUTION: A light emitting diode element is sealed with epoxy resin which contains sulfonium salt shown in a general formula as hardening catalyst. In the formula, Ar expresses aromatic ring, R<1> expresses substitution or nonsubstitution-hydrocarbon group, hydroxyl group, alkoxyl group, nitro group, cyano group or halogen atom, (a) expresses 0.1 to 2, and when (a) is 2, R<1> can be the same or differ each other; R<2> and R<3> express hydrogen atom or methyl group, respectively; R<4> is the same or differs each other and expresses substitution or nonsubstitution-univalent hydrocarbon group. Since sulfonium salt has high transparency and does not cause corrosion and electrical deterioration at a high temperature, a sealing layer which is excellent in light permeability and excellent in humidity resistance can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting diode device, and more particularly, to a light emitting device in which a light emitting diode element is sealed with an epoxy resin cured with a sulfonium salt having a specific molecular structure. It relates to a diode device.

[0002]

2. Description of the Related Art Epoxy resin molding materials are widely used as sealing agents for light emitting diodes by making use of their properties such as mechanical properties, adhesion, wet-tightness, and electrical insulation.

Among epoxy resin curing agents, phenolic resin-based curing agents such as phenol novolak and amino-based compounds such as polyamines cause marked coloration of the cured product, the former has a slow reaction, and the latter has safety. And is poor in moisture resistance, so that it is not suitable as a sealant for light emitting diodes. An acid anhydride-based curing agent gives a cured product having good transparency, but also has poor moisture resistance.

[0004] In order to improve the workability of the sealing operation using an epoxy resin, various types of epoxy resin compositions have been proposed which can store all components in a single package using a special catalyst. For example, at room temperature, it is solid and does not dissolve in the epoxy resin, but when heated to near the melting point, as a latent catalyst that dissolves in the epoxy resin and rapidly undergoes a curing reaction, boron trifluoride / amine complex, dicyandiamide and its derivatives, and Organic acid hydrazides such as adipic acid dihydrazide are known. These systems have excellent storage properties of the epoxy resin composition at room temperature, but since the catalyst does not dissolve in the epoxy resin, it is necessary to paste and disperse it. In addition, there is a problem that the apparent viscosity of the system decreases, the dispersion of the catalyst becomes unstable, and the system becomes uneven. Also, the reaction is slow. On the other hand, using such a system,
When the reaction speed is increased by heating, heat is generated rapidly, causing deterioration and foaming.

Further, it is known that various onium salts are used as a latent catalyst for curing an epoxy resin. When an onium salt is used in combination with another catalyst system, a high reaction rate can be obtained at a relatively low temperature.However, in this method, depending on the catalyst system used in combination, a decrease in moisture resistance or turbidity due to poor dispersibility, Only an unsuitable catalyst system for sealing a light emitting diode, such as a precipitate, has been obtained. In addition, onium salt-based catalysts also generally have problems such as insufficient transparency and influence of ionicity on electrical characteristics.

[0006] JP-A-3-115427 discloses a diaryliodonium hexafluoroantimonate salt.
It is disclosed that, together with a radical-generating aromatic compound such as benzopinacol, it is used as a latent curing catalyst for a solid epoxy resin, and as an encapsulant for a semiconductor device, it imparts excellent moisture resistance to the device. However, this diaryliodonium salt has poor stability and is difficult to handle.

Japanese Unexamined Patent Publication (KOKAI) Showa No. 63-152219 discloses a naphthylmethyl group;
JP-A-63-223002 discloses that a sulfonium salt having a 4-alkoxybenzyl group is used as a latent curing catalyst for an epoxy resin. It is described that it can be applied to a sealing material. However, the use of these for sealing light emitting diodes is not disclosed.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to efficiently seal a light emitting diode element by using an epoxy resin-curing agent system having fluidity and excellent workability to transmit light. An object of the present invention is to provide a light-emitting diode device having a sealing layer having good resistance and excellent moisture resistance.

[0009]

Means for Solving the Problems As a result of repeated studies to achieve the above object, the present inventor has found that a sulfonium salt of hexafluoroantimonic acid having a specific onium structure as a sealant for a light emitting diode element. The use of an epoxy resin with a latent catalyst provides a very high cure rate and molding cycle in the encapsulation work, and the resulting encapsulation layer has high moisture resistance and translucency Moreover, it has been found that such a sulfonium salt does not cause corrosiveness at high humidity and does not adversely affect the characteristics of a sealed device despite having a halogen atom in the molecule. Thus, the present invention has been completed.

That is, in the light emitting diode device of the present invention, the light emitting diode element has a general formula:

Embedded image (Wherein, Ar represents an aromatic ring; R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group, a hydroxyl group, an alkoxyl group, a nitro group, a cyano group or a halogen atom;
Or 2 and when a is 2, R ¹ may be the same or different from each other; R ² and R ³ each represent a hydrogen atom or a methyl group; R ⁴ is the same or different and is substituted or unsubstituted Which represents a monovalent hydrocarbon group of the present invention) as a curing catalyst.

The light emitting diode element used in the present invention is GaP, GaAs, GaAsP, GaAlAs, G
Examples thereof include pn junctions of aN, SiC, and the like, and solid solutions thereof, and may include an activator and may be of any color. Examples of the substrate include the same compounds and sapphire as described above, and are not particularly limited. These elements may or may not be provided with a passivation layer. Also, the shape and dimensions are not limited. Parts necessary for the light emitting diode, such as electrodes and lead wires, can be provided by a usual method.

In the present invention, the epoxy resin used as a main component of the encapsulant may be a liquid or a solid at room temperature as long as it is a system capable of obtaining the transparency required as an encapsulant for a light emitting diode. However, from the viewpoint of workability in the sealing operation, any one of (1) a liquid at room temperature and a liquid or a solid at room temperature, which is diluted with a diluent and shows a liquid at room temperature, It is preferred that Here, the epoxy resin has any molecular structure as long as it has two or more oxirane rings in one molecule and cures in the presence of a catalyst or a curing agent to form a resinous polymer. But you can. Epoxy resin is 1
The species may be used alone, or two or more species may be used in combination.

Here, the term "liquid at normal temperature" means 25 to 40.
It has fluidity at ° C, and includes a so-called semi-solid. In addition, a substantially uniform mixture of an epoxy resin and a solid epoxy resin that are liquid at room temperature and liquid at room temperature after mixing is included in the liquid epoxy resin.

(1) Bisphenol A type epoxy resin having an average molecular weight of about 500 or less; bisphenol F type epoxy resin; phenol novolak type epoxy resin having an average molecular weight of about 570 or less 1,2-epoxyethyl-3,
Alicyclic epoxy resins such as 4-epoxycyclohexane, 3,4-epoxycyclohexylcarboxylic acid-3,4-epoxycyclohexylmethyl, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate; hexahydrophthalic Glycidyl ester type epoxy resin such as diglycidyl acid, diglycidyl 3-methylhexahydrophthalate, diglycidyl hexahydroterephthalate; diglycidylaniline, diglycidyltoluidine, triglycidyl-p-aminophenol, tetraglycidyl-m-xylylenediamine Glycidylamine type epoxy resins such as tetraglycidylbis (aminomethyl) cyclohexane; and hydantoin type epoxy resins such as 1,3-diglycidyl-5-methyl-5-ethylhydantoin Resins.

(2) As a main component of the curable liquid composition diluted with a diluent, a solid epoxy resin may be used in addition to the above-mentioned liquid epoxy resin. That is, examples of the epoxy resin to be used include bisphenol A type epoxy resin, bisphenol F type epoxy resin, alicyclic epoxy resin, glycidyl ester type epoxy resin, glycidylamine type epoxy resin and hydantoin type epoxy resin.

As the diluent, any diluent can be used as long as the system can maintain fluidity by dissolving or dispersing the epoxy resin. The diluent may be a reactive diluent which participates in a curing reaction by a sulfonium compound or a non-reactive diluent. Good, but to prevent shrinkage, foaming, voids, etc. during curing,
Reactive diluents are preferred.

One or two reactive diluents are used per molecule.
An epoxy compound having at least one oxirane ring and having a relatively low viscosity at room temperature. Depending on the purpose, besides the oxirane ring, other polymerizable functional groups such as alkenyl groups such as vinyl and allyl; or acryloyl and methacryloyl May have an unsaturated carboxylic acid residue. Examples of such a reactive diluent include n-butyl glycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, cresyl glycidyl ether,
Monoepoxide compounds such as p-sec-butylphenyl glycidyl ether, styrene oxide and α-pinene oxide; having other functional groups such as allyl glycidyl ether, glycidyl methacrylate, 1-vinyl-3,4-epoxycyclohexane Monoepoxide compounds;
(Poly) ethylene glycol diglycidyl ether,
(Poly) propylene glycol diglycidyl ether,
Examples include diepoxide compounds such as butanediol diglycidyl ether and neopentyl glycol diglycidyl ether; and triepoxide compounds such as trimethylolpropane triglycidyl ether and glycerin triglycidyl ether.

Non-reactive diluents include high-boiling aromatic hydrocarbons such as p-cymene and tetralin; glycerin;
High-boiling alcohols such as 2-methylcyclohexanol; plasticizers such as dibutyl phthalate, dioctyl phthalate and dibutylbenzyl phosphate are exemplified. The diluent (2) may be used in an amount of 40% by weight or less based on the whole curable liquid composition. If the content of (2) is within 10% by weight or less, preferably 2% by weight or less, a lower boiling organic solvent such as xylene, methyl ethyl ketone or methyl isobutyl ketone may be used. The use of such an organic solvent tends to cause foaming and thinning during curing, so that attention must be paid to the work.

The sulfonium salt used in the present invention can coexist stably with the epoxy resin at room temperature, cures the epoxy resin by heating, and when a reactive diluent is mixed in the epoxy resin, the sulfonium salt reacts with the epoxy resin. It is a latent catalyst that functions as a catalyst for curing a diluent.

The sulfonium salt has the general formula:

Embedded image (Wherein, E, Ar, R ¹ , R ² , R ³ , R ⁴ and a are as described above), and a sulfur atom is represented by —C (R ² R ³ ) —.
Is a sulfonium hexafluoroantimonate having an aromatic ring Ar bonded through Examples of such Ar include a benzene ring, a naphthalene ring, an anthracene ring and a pyrene ring, and a benzene ring is preferable because of easy synthesis.

Examples of the sulfonium salt include benzyl, α-methylbenzyl, 1-naphthylmethyl, 2-
Hexafluoroantimonate having an arylmethyl group such as naphthylmethyl may be mentioned, and the above-mentioned aromatic ring may have a substituent. It is preferable because it can be performed.

The aromatic ring Ar may be unsubstituted or substituted with one or two R ¹ . R ¹ is methyl, ethyl, propyl, butyl, pentyl, octyl,
Linear or branched alkyl groups such as decyl, dodecyl and tetradecyl; cycloalkyl groups such as cyclohexyl; aryl groups such as phenyl and naphthyl; alkaryl groups such as tolyl and xylyl;
Aralkyl groups such as phenylethyl; alkenyl groups such as vinyl, allyl and butenyl; monovalent substituted hydrocarbon groups such as chloromethyl; hydroxyl groups; alkoxyl groups such as methoxy, ethoxy, propoxy and tert-butoxy; Nitro groups; cyano groups; and halogen atoms such as fluorine, chlorine, bromine and iodine. The position at which R ¹ is introduced is arbitrary, but, for example, when Ar is a benzene ring, the 2-position and / or
Alternatively, the 4-position is preferable, and when R ^{1 is a} bulky group, the 4-position is particularly preferable since the activity is not reduced by steric hindrance.

R ² and R ³ are each independently a hydrogen atom or a methyl group, and preferably a hydrogen atom because of easy synthesis, but when it is necessary to increase the catalytic activity, R ² and R 3 at least one of the ³ is preferably a methyl group.

R ⁴ is methyl, ethyl, propyl, butyl, pentyl, octyl, decyl, dodecyl,
Linear or branched alkyl groups such as tetradecyl; cycloalkyl groups such as cyclohexyl; aryl groups such as phenyl and naphthyl; alkaryl groups such as tolyl and xylyl; Aralkyl groups; alkenyl groups such as vinyl, allyl and butenyl; and monovalent substitutions such as hydroxyphenyl, methoxyphenyl, ethoxyphenyl, cyanophenyl, chlorophenyl, acetoxyphenyl, propanoylphenyl, methoxycarbonylphenyl, ethoxycarbonylphenyl Examples are hydrocarbon groups.

Representative examples of such sulfonium salts include dimethylbenzyl sulfonium hexafluoroantimonate and dimethyl hexafluoroantimonate (4-
Methylbenzyl) sulfonium, dimethyl hexafluoroantimonate (4-methoxybenzyl) sulfonium, dimethyl hexafluoroantimonate (4-ethoxybenzyl) sulfonium, dimethyl hexafluoroantimonate (4-tert-butoxybenzyl) sulfonium, hexafluoroantimonic acid Dimethyl (4-nitrobenzyl) sulfonium, dimethyl (4-cyanobenzyl) sulfonium hexafluoroantimonate, (4-chlorobenzyl) sulfonium hexafluoroantimonate, methylphenylbenzylsulfonium hexafluoroantimonate, methylhexafluoroantimonate (4 -Hydroxyphenyl) benzylsulfonium, methyl hexafluoroantimonate (4-methoxyphenyl) benzylsulfonate Ium, dimethyl hexafluoroantimonate (1-naphthylmethyl) sulfonium, methylphenyl hexafluoroantimonate (1-naphthylmethyl) sulfonium, methyl hexafluoroantimonate (4-hydroxyphenyl) (1-naphthylmethyl) sulfonium, hexafluoro Methyl antimonate (4-methoxyphenyl) (1-naphthylmethyl) sulfonium, dimethyl hexafluoroantimonate (α-
Methylbenzyl) sulfonium and the like.

The amount of the sulfonium salt used is such that an epoxy resin (hereinafter referred to as reactive dilution) can be used because a satisfactory curing rate can be obtained, the stability of the system in an uncured state, and the properties of the sealing layer after curing are excellent. When the composition contains an agent, the total amount thereof is usually 0.1 to 1 with respect to 100 parts by weight.
0 parts by weight, preferably 0.5 to 5 parts by weight.

The sealant used in the present invention contains an epoxy resin, preferably the above-mentioned liquid epoxy resin, or a curable mixture of an epoxy resin and a diluent, and the above-mentioned sulfonium salt. These are evenly mixed,
Long-term storage is possible at room temperature. The encapsulant additionally provides thixotropic properties when the encapsulation is raised, to maintain the uncured state or to scatter light generated by the diode. Up to 10 parts by weight of fumed silica, powdered silica such as contact silica; and inorganic powders such as calcium carbonate and titanium oxide may be contained in a range that does not impair the necessary light transmittance. further,
If necessary, as long as it does not adversely affect the light transmission,
Additives such as an internal release agent, a flame retardant, a flame retardant auxiliary, a silane or titanium coupling agent, a pigment, and a dye can be added.

The light emitting diode device of the present invention can be formed, for example, by injection molding or transfer molding so as to encapsulate the light emitting diode element in a mold into which the light emitting diode element is inserted, for example, a conventional RIM injection molding machine or transfer molding machine. Using 100 to 200
The sealing layer can be molded and cured at a temperature of preferably from 120 to 180 ° C. The curing time is not particularly limited, and can be arbitrarily set according to the resin composition, the size and shape of the sealing body, and the molding temperature. However, the curing speed of the epoxy resin at the above molding temperature is extremely fast, and the gelation time is 150 ° C. 60 ° C
Within seconds, preferably within 30 seconds.

The shape of the light emitting diode device can be any type such as a lamp type, a display type and a raised type.

[0030]

According to the light emitting diode device of the present invention, since the sealing layer is formed by heating at a relatively low temperature and for a short time, the molding cycle of injection molding or transfer molding can be shortened. Loss due to heat and stress on the light emitting diode element. Further, the sealant used in the present invention,
Even if a curing catalyst is mixed in advance, it can be stably stored at room temperature for a long period of time, and there is no need to mix the curing catalyst immediately before use, which greatly contributes to rationalization of the manufacturing process of the light emitting diode device. Especially when using a liquid epoxy resin, or a curable liquid mixture consisting of an epoxy resin and a diluent,
Because of the fluidity during the sealing operation, the workability is excellent.

The sulfonium salt used in the present invention provides a highly transparent sealing layer as compared with other corresponding onium salts. Also, it does not cause corrosion or electrical deterioration at high temperatures. Therefore, the light emitting diode device of the present invention is excellent in moisture resistance, light transmission and durability, and can be stably used in various environments.

[0032]

The present invention will be described below in more detail with reference to Examples and Comparative Examples. The present invention is not limited by these examples. In these examples and comparative examples, parts are parts by weight, and% of composition is% by weight.
Represents

In the examples and comparative examples, the following epoxy resins were used. E-1: bisphenol A-epichlorohydrin liquid epoxy resin, molecular weight 380, purified product; E-2: 3,4-epoxycyclohexanecarboxylic acid-
3,4-epoxycyclohexyl; and E-3: a curable mixture composed of 85% of a bisphenol A-epichlorohydrin-based solid epoxy resin having a molecular weight of 900 and 15% of phenylglycidyl ether.

In the examples and comparative examples, the following were used as the sulfonium salt, or as a curing agent and a curing catalyst for comparison. S-1: methyl hexafluoroantimonate (4-hydroxyphenyl) benzylsulfonium, S-2: methyl hexafluoroantimonate (4-methoxyphenyl) -1-naphthylmethylsulfonium, MHHPA: methylhexahydrophthalic anhydride, and DBU: 1,8-diazabicyclo [5.4.0] -7-
Undecene

Examples 1-4, Comparative Example According to the mixing ratio shown in Table 1, the epoxy resin and the sulfonium salt or the curing agent and the curing catalyst for comparison were mixed at room temperature to obtain a uniform mixture. . However, Example 4
Then, by heating to 60 ° C., S-2 was converted to E-1.
And completely cooled to room temperature. Similarly, in the comparative example, the system was heated to 90 ° C. to uniformly dissolve the system, and then cooled to room temperature. The gelling time of the thus obtained sealant was measured on a hot plate set at 150 ° C. The results were as shown in Table 1.

[0036]

[Table 1]

Next, GaAs _0.25 P _0.75 was deposited on the GaP substrate.
A pn bond of the liquid phase epitaxial growth layer is formed, and the same-shaped light emitting diode element provided with the electrodes and the lead wires is sealed with each of the above-mentioned sealing agents to obtain 12
5mm in diameter by heating and curing at 5 ° C for 8 hours
A raised light emitting diode device having the same shape of the sealing outer shape was manufactured. Each of the five devices thus obtained was subjected to the temperature and humidity shown in Table 2 for 2 hours.
An operation endurance test was performed for 1,000 hours while applying 0 mA DC to emit light. As a result, as shown in Table 2, none of the devices of Examples 1 to 4 had any abnormality. On the other hand, the sample of the comparative example has 6
After 4 hours, 4 out of 5 samples were unlit. In addition, all of the devices of Examples 1 to 4 were subjected to a temperature of 65 ° C.
No change in characteristics was observed in high-temperature and high-humidity storage at 95% RH, high-temperature storage at 80 ° C, and low-temperature storage at -30 ° C, and heat shock at -40 ° C for 30 minutes to + 80 ° C for 30 minutes. No crack, disconnection, or reduction in luminance was observed in 200 cycles of the test.

[0038]

[Table 2]

Claims (2)

[Claims] The light-emitting diode element has a general formula: (Wherein, Ar represents an aromatic ring; R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group, a hydroxyl group, an alkoxyl group, a nitro group, a cyano group or a halogen atom;
Or 2 and when a is 2, R ¹ may be the same or different from each other; R ² and R ³ each represent a hydrogen atom or a methyl group; R ⁴ is the same or different and is substituted or unsubstituted A light-emitting diode device characterized by being sealed with an epoxy resin containing a sulfonium salt represented by the formula (1) as a curing catalyst: 2. The light emitting diode device according to claim 1, wherein the epoxy resin is a liquid epoxy resin or a curable liquid mixture comprising an epoxy resin and a diluent.