JP3618238B2 - Light emitting diode - Google Patents

Light emitting diode Download PDF

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Publication number
JP3618238B2
JP3618238B2 JP37135398A JP37135398A JP3618238B2 JP 3618238 B2 JP3618238 B2 JP 3618238B2 JP 37135398 A JP37135398 A JP 37135398A JP 37135398 A JP37135398 A JP 37135398A JP 3618238 B2 JP3618238 B2 JP 3618238B2
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Prior art keywords
epoxy resin
light
weight
light emitting
parts
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JP2000196151A (en
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雅史 蔵本
智也 月岡
昌司 東丸
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Nichia Corp
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Nichia Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/26—Layer connectors, e.g. plate connectors, solder or adhesive layers; Manufacturing methods related thereto
    • H01L2224/31—Structure, shape, material or disposition of the layer connectors after the connecting process
    • H01L2224/32—Structure, shape, material or disposition of the layer connectors after the connecting process of an individual layer connector
    • H01L2224/321—Disposition
    • H01L2224/32151—Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
    • H01L2224/32221—Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
    • H01L2224/32245—Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/26—Layer connectors, e.g. plate connectors, solder or adhesive layers; Manufacturing methods related thereto
    • H01L2224/31—Structure, shape, material or disposition of the layer connectors after the connecting process
    • H01L2224/32—Structure, shape, material or disposition of the layer connectors after the connecting process of an individual layer connector
    • H01L2224/321—Disposition
    • H01L2224/32151—Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
    • H01L2224/32221—Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
    • H01L2224/32245—Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic
    • H01L2224/32257—Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic the layer connector connecting to a bonding area disposed in a recess of the surface of the item
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/44—Structure, shape, material or disposition of the wire connectors prior to the connecting process
    • H01L2224/45—Structure, shape, material or disposition of the wire connectors prior to the connecting process of an individual wire connector
    • H01L2224/45001—Core members of the connector
    • H01L2224/45099—Material
    • H01L2224/451—Material with a principal constituent of the material being a metal or a metalloid, e.g. boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te) and polonium (Po), and alloys thereof
    • H01L2224/45138—Material with a principal constituent of the material being a metal or a metalloid, e.g. boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te) and polonium (Po), and alloys thereof the principal constituent melting at a temperature of greater than or equal to 950°C and less than 1550°C
    • H01L2224/45144—Gold (Au) as principal constituent
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/4805—Shape
    • H01L2224/4809—Loop shape
    • H01L2224/48091—Arched
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/481—Disposition
    • H01L2224/48151—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
    • H01L2224/48221—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
    • H01L2224/48245—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic
    • H01L2224/48247—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic connecting the wire to a bond pad of the item
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/73—Means for bonding being of different types provided for in two or more of groups H01L2224/10, H01L2224/18, H01L2224/26, H01L2224/34, H01L2224/42, H01L2224/50, H01L2224/63, H01L2224/71
    • H01L2224/732—Location after the connecting process
    • H01L2224/73251—Location after the connecting process on different surfaces
    • H01L2224/73265—Layer and wire connectors

Description

【０００１】
【発明の実施の形態】
本発明は各種インジケータ、ＬＥＤディスプレイやバックライトの光源などに利用される発光ダイオードに関わり、特に、信頼性が高く経時変化の少ない発光ダイオードに関するものである。
【０００２】
【従来技術】
今日、１０００ｍｃｄ以上も発光可能な発光ダイオードが、ＲＧＢ共に開発され種々の分野に利用され始めている。このような発光ダイオードの一例として図４に示す如きものが挙げられる。図４には発光ダイオードの模式的断面図を示している。
【０００３】
図中、リード電極として働くカップを有するマウント・リード４０５と、インナー・リード４０６が設けられている。このマウントリードのカップ上にダイボンド樹脂４０３を用いてＬＥＤチップ４０２を載置させている。ＬＥＤチップの電極と、インナーリード４０６とを電気的に接続させるべくワイヤ４０４によりインナー・リードとワイヤボンディングされている。他方、ＡｇペーストによりＬＥＤチップの他方の電極とマウントリード４０５とを電気的に接続させてある。こうしてリード電極と電気的に接続されたＬＥＤチップやワイヤを、外部環境から保護するなどの目的で透光性樹脂４０１によりモールドさせてある。
【０００４】
モールド樹脂となる透光性樹脂４０１は、あらかじめ砲弾型など所望の形状が得られる型となるキャスティングケース内にエポキシ樹脂を注入させる。型の中に注入されたエポキシ樹脂に、ＬＥＤチップ及びリード電極の一部を差込み固定させる。この状態でエポキシ樹脂を硬化させる。硬化後、キャスティングケースから取り出すことにより発光ダイオードを形成させることができる。これにより比較的簡単な構成でＬＥＤチップを保護すると共に所望の配光特性などを効率よく得られる発光ダイオードを構成することができる。
【０００５】
特に、発光ダイオードに利用されるモールド樹脂の特性として、１．リードフレームやＬＥＤチップなどとの密着性に優れていること、２．機械的強度が高く耐衝撃性に優れていること、３．金型寸法設計が容易で形成時の応力によりＬＥＤチップなどに損傷が生じにくい低応力であること、４．低収縮性及び金型からの抜けである抜け性に優れていること、５．回路基板に半田などにより実装するときや駆動時などに生ずる、Ｔｇ（ガラス転移点）以上の熱による変形が極めて少ないこと、６．気泡などが生じにくいボイドフリー且つ低粘度であること、及び７．発光ダイオードとして最も重要な項目の１つとして、ＬＥＤチップから放出される光に対して優れた透光性を有することが要求される。このような発光ダイオード特有の特性により、モールド部材としてはエポキシ樹脂を利用することが好ましい。
【０００６】
エポキシ樹脂のモールド部材として例えば特開平６−３１６６２６号公報に示す如くビスフェノール型エポキシ樹脂やビスフェノール型ウレタン変性エポキシ樹脂を主構成樹脂として使用したものが挙げられる。ビスフェノールＡジグリシジルエーテルに代表されるフェノール系エポキシ樹脂は、上記特性を満たすと共に可視光における透光性が特に優れている。
【０００７】
他方、今日の発光ダイオード技術の飛躍的な進歩により、ＬＥＤチップの高出力化及び短波長化が急速に現実のものとなり始めている。具体的には、窒化物半導体を用いたＬＥＤでは、発光層の組成を構成する元素によって主発光ピークが約３６５ｎｍから６５０ｎｍの任意発光ピークで発光可能であり、特に５５０ｎｍ以下の可視光（具体的には近紫外域光から青緑色光など）でも、比較的簡単に高効率なＬＥＤチップを形成することができる。また、発光出力も窒化物半導体の発光層に多重量子井戸構造を利用することで５ｍＷ以上のもの高出力が発光可能な発光ダイオードとすることができる。
【０００８】
【発明が解決しようとする課題】
しかしながら、より短波長且つ高出力発光可能なＬＥＤチップを単に、上述のエポキシ樹脂などで封止すると、経時的に樹脂の劣化による発光輝度が顕著に低下するなどの不都合が生ずるという新たな問題が生じる。より具体的には、発光ダイオード用モールド樹脂の特性を満たしたエポキシ樹脂の１種としてビスフェノールＡジグリシジルエーテルを主体として利用し、エネルギーの比較的低い緑色から赤色にかけて発光するＬＥＤチップを用いた発光ダイオードでは、ＬＥＤチップから放出された光のみでモールド樹脂が劣化することは実質上極めて少なく効率よく発光させることが可能である。
【０００９】
しかし、可視光の短波長側である５５０ｎｍ以下に主発光ピークを発するＬＥＤチップでは、可視光の長波長が発光可能な発光ダイオードと同様に形成させても経時的に輝度が急激に低下する。そこで、本発明は上記発光ダイオードのモールド樹脂に要求される特性を満たしつつ、特定のＬＥＤチップを利用した場合にも経時変化が極めて少なく光利用効率の優れた発光ダイオードを提供することにある。
【００１０】
【課題を解決するための手段】
本発明の発光ダイオードは、少なくとも一対のリード電極と電気的に接続させた発光素子と、発光素子を被覆する透光性樹脂とを有する発光ダイオードであって、発光素子は、５５０ｎｍ以下の近紫外光から可視光に主発光ピークを発する発光層を有し、透光性樹脂は、フェノール誘導体エポキシ樹脂が１０％未満のエポキシ樹脂組成物であり、エポキシ樹脂組成物は、エポキシ樹脂１００重量部に対し、（ａ）炭素二重結合を化学的に有しない多塩基酸カルボン酸無水物を５０から１５０重量部、（ｂ）非芳香族かつ炭素二重結合を有しない炭素数２〜１２の直鎖型、分岐型、脂環型、エーテル基含有型のいずれかからなるアルコール・ポリオール類を１から３０重量部、（ｃ）ホスフィン類及び／又はそれらの第四級塩を０．０１〜１重量部、若しくは炭素二重結合を有しない有機カルボン酸金属塩を１から１０重量部、含み、経時劣化による黄変着色を低下させてなることを特徴とする発光ダイオードである。これにより量産性に優れ透光性を満たしつつ、経時劣化の少ない発光ダイオードとすることができる。また助触媒として働くアルコール・ポリオール類がエポキシ樹脂組成物に加えられることで硬化物に可とう性が付与され、剥離接着力を向上させることができる。さらに助触媒として働くアルコール・ポリオール類は、硬化促進剤として働くホスフィン類、有機カルボン酸金属塩等の相溶化剤としても機能し、硬化促進剤として働く有機カルボン酸金属塩等の機能を発揮させ、より硬化性を向上させることができる。
【００１１】
本発明の請求項２に記載の発光ダイオードは、少なくとも一対のリード電極と電気的に接続させた発光素子と、該発光素子を被覆する透光性樹脂とを有する発光ダイオードであって、発光素子は、発光層が５５０ｎｍ以下に主発光ピークを発する少なくともＩｎとＧａを含有する窒化物半導体であり、透光性樹脂のエポキシ樹脂は、９０％以上が非芳香族のエポキシ樹脂組成物であり、エポキシ樹脂組成物は、エポキシ樹脂１００重量部に対し、（ａ）炭素二重結合を化学的に有しない多塩基酸カルボン酸無水物を５０から１５０重量部、（ｂ）非芳香族かつ炭素二重結合を有しない炭素数２〜１２の直鎖型、分岐型、脂環型、エーテル基含有型のいずれかからなるアルコール・ポリオール類を１から３０重量部、（ｃ）ホスフィン類及び／又はそれらの第四級塩を０．０１〜１重量部、若しくは炭素二重結合を有しない有機カルボン酸金属塩を１から１０重量部、含み、経時劣化による黄変着色を低下させてなることを特徴とする発光ダイオードである。これにより量産性に優れ透光性を満たしつつ、経時劣化の少ない発光ダイオードとすることができる。また助触媒として働くアルコール・ポリオール類がエポキシ樹脂組成物に加えられることで硬化物に可とう性が付与され、剥離接着力を向上させることができる。さらに助触媒として働くアルコール・ポリオール類は、硬化促進剤として働くホスフィン類、有機カルボン酸金属塩等の相溶化剤としても機能し、硬化促進剤として働く有機カルボン酸金属塩等の機能を発揮させ、より硬化性を向上させることができる。
【００１２】
本発明に記載の発光ダイオードは、非芳香族エポキシ樹脂組成物が脂環式エポキシ樹脂及び／又は含窒素エポキシ樹脂であるのが好ましい。これにより、より簡便に信頼性の高い発光ダイオードを形成させることができる。
【００１３】
本発明に記載の発光ダイオードとすることにより、脂環式エポキシ樹脂がシクロヘキセンエポキシ化物誘導体、水素化ビスフェノールＡジグリシジルエーテル、ヘキサヒドロフタル酸グリシジルエステル、含窒素エポキシ樹脂から選択される少なくとも１種であるのが好ましい。これにより、より簡便に信頼性の高い発光ダイオードを形成させることができる。
【００１４】
本発明に記載の発光ダイオードは、含窒素エポキシ樹脂がトリグリシジルイソシアヌレートであるのが好ましい。これにより、より簡便に信頼性の高い発光ダイオードを形成させることができる。
【００１５】
【発明の実施の形態】
本発明者は種々の実験の結果、可視光の短波長から紫外域を発光するＬＥＤチップを特定のエポキシ樹脂で封止することにより、比較的簡単な構成で信頼性の高い発光ダイオードとすることができることを見いだし本発明をなすに至った。
【００１６】
即ち、近紫外域（なお、本願明細書では、窒化物半導体で発光可能な３６５ｎｍ以上をいうとする。）から可視光の短波長側で高出力に発光するＬＥＤチップを被覆する透光性樹脂は、その界面近傍からＬＥＤチップ自体が発する光や熱により急激に樹脂が劣化する。特に、炭素炭素間の二重結合を有する芳香族エポキシ樹脂を透光性樹脂に利用した発光ダイオードでは、一旦ＬＥＤチップからの光や熱エネルギーにより二重結合が切れ酸化されると、それによる黄変着色を起こす。
【００１７】
黄変着色は単に樹脂を着色させるだけでなく、５５０ｎｍ以下の可視光、特に青色に対して補色関係或いは補色に近い。そのため、ＬＥＤチップからの光が吸収され易く、劣化が促進されると考えら得る。また、近紫外域から可視光の短波長を５ｍＷ以上の高出力が発光可能な多重量子井戸構造などの窒化物半導体を利用した場合、顕著に現れ易い傾向にある。
【００１８】
本発明者は発光ダイオードに利用される透光性樹脂の特性を持ちつつ、劣化の原因となる炭素炭素間の二重結合を有しない非芳香族エポキシ樹脂を主体のエポキシ樹脂組成物を透光性樹脂に選択した。これにより、初期の可視光透過率が若干低くなるものの、ＬＥＤチップを封止したことにより生ずるＬＥＤチップからの劣化を防止し経時劣化を生ずることなく信頼性の高い発光ダイオードとすることができる。以下、本発明の構成について詳述する。
【００１９】
（透光性樹脂）透光性樹脂となる本発明のエポキシ樹脂組成物は、ＬＥＤチップを被覆するものである。したがって、高耐光性と絶縁性及び透光性が要求されるため、着色原因となる芳香族成分、特にフェノール誘導体エポキシ樹脂を組成物中１０ｗｔ％未満とすることが好ましく、より好ましくは５％未満である。なお、フェノール誘導体エポキシ樹脂を全く含有させないものが最も耐光性に優れることとなる。また、非芳香族エポキシ樹脂がエポキシ樹脂組成物中のエポキシ成分として９０％以上が好ましく、より好ましくは９５％以上である。として無機塩素含有量を１ｐｐｍ以下、有機塩素含有量を５ｐｐｍ以下とすることができるエポキシ樹脂が好ましい。特に蒸留生成され塩素成分を全く含有しないものがより好ましい。
【００２０】
具体的には、３，４エポキシシクロヘキシルメチル−３′，４′エポキシシクロヘキシルカルボキシレートに代表される脂環式エポキシ樹脂を単独又は２種以上を混合し使用することができる。また、脂環式エポキシ樹脂を主体にヘキサヒドロフタル酸ジグリシジルエステル、水素化ビスフェノールＡジグリシジルエーテルなどのシクロヘキサン誘導体とエピクロルヒドリンよりなるエポキシ樹脂、ビスフェノールＡジグリシジエーテルよりなる液状又は固形のエポキシ樹脂なども必要に応じ混合使用することもできる。同様に含窒素エポキシ樹脂としてトリグリシジルイソシアヌレートが好適に挙げることができる。また、この本発明のエポキシ樹脂組成物は、発光ダイオードの形態によって種々の形状とさせることができる。また、所望に応じて蛍光物質、拡散剤及び着色剤を種々含有させることもできる。エポキシ樹脂組成物には上述のエポキシ樹脂の他、下記の如き硬化剤、助触媒、硬化促進剤を適宜混合させることができる。
【００２１】
（硬化剤）エポキシ樹脂組成物に好適に含有される酸無水物は、耐光性を必要とするため非芳香族かつ炭素二重結合を化学的に有しない多塩基酸カルボン酸無水物の一種又は二種以上が好ましい。具体的にはヘキサヒドロ無水フタル酸、メチルヘキサヒドロ無水フタル酸、トリアルキルテトラヒドロ無水フタル酸、水素化メチルナジック酸無水物などが挙げられる。
【００２２】
特に、酸無水物として硬化反応性と耐湿性のバランスの良いメチルヘキサヒドロ無水フタル酸をエポキシ樹脂１００重量部に対し５０から１５０重量部配合したものが好ましく、８０から１３０重量部配合したものがより好ましい。
【００２３】
（助触媒）助触媒はエポキシ樹脂組成物に好適に含有される。助触媒として働くアルコール・ポリオール類は、硬化物に可とう性を付与し剥離接着力を向上させるだけでなく後述する硬化促進剤の相溶化剤としても機能する。アルコール・ポリオール類も耐光性を要求されるため非芳香族かつ炭素二重結合を化学構造的に有しない炭素数２〜１２の直鎖型、分岐型、脂環型、エーテル基含有型のいずれかからなるアルコール・ポリオール類が好適に用いられる。具体的にはプロパノール、イソプロパノール、メチルシクロヘキサノール、エチレングリコール、グリセリン、トリメチロールプロパン、エチレングリコールモノメチルエーテルなどが挙げられる。
【００２４】
アルコール・ポリオール類は、硬化促進剤の相溶化剤でもあるため硬化促進剤の化学構造と配合量に影響を受けるが、エチレングリコールなどの低分子量ジオールが１から３０重量部の少量配合で好ましく、５から１５重量部がより好ましい。
【００２５】
（硬化促進剤）硬化促進剤はエポキシ樹脂組成物に好適に含有される。硬化促進剤としては、１．第三級アミン類若しくはイミダゾール類及び／又はそれらの有機カルボン酸塩、２．ホスフィン類及び／又はそれらの第四級塩、３．有機カルボン酸金属塩、４．金属−有機キレート化合物、５．芳香族スルホニウム塩が挙げられ単独または２種以上を混合して使用することができる。
【００２６】
第三級アミン類、イミダゾール類とその有機カルボン酸塩として具体的には、２，４，６−トリス（ジアミノメチル）フェノール、２−エチル−４−メチルイミダゾール、１，８−ジアザビスシクロ（５，４，０）ウンデセン−７（以下ＤＢＵ）とそのオクチル酸塩などが挙げられる。特に硬化物の透光性に優れるＤＢＵオクチル酸塩をエポキシ樹脂１００重量部に対して０．０１〜１重量部配合したものが好ましく、発光ダイオードの耐湿特性を考慮したならば０．１〜０．５重量部配合したものがより好ましい。
【００２７】
ホスフィン類とその第四級塩として具体的にはトリフェニルホスフィン、トリブチルホスフィン、ベンジルトリフェニルホスホニウム臭素塩、ベンジルトリブチルホスホニウム臭素塩などが挙げられる。特に硬化物の透光性に優れるベンジルトリフェニルホスホニウム臭素塩をエポキシ樹脂１００重量部に対して０．０１〜１重量部配合したものが好ましく、発光ダイオードの耐湿特性を考慮したならば０．１〜０．５重量部配合したものがより好ましい。
【００２８】
有機カルボン酸金属塩として具体的には耐光性に劣る炭素二重結合を有さないオクチル酸亜鉛、ラウリン酸亜鉛、ステアリン酸亜鉛、オクチル酸錫などが挙げられる。有機カルボン酸金属塩は、有機カルボン酸成分の炭素数増加と比例しエポキシ樹脂への溶解性が低下する。オクチル酸亜鉛は配合量に最も幅を有しており、また液状であるため分散溶解に時間を要さない。したがって、硬化性の観点からオクチル酸亜鉛を１から１０重量部配合することが好ましい。硬化物の透光性を考慮したならば１から５重量部がより好ましい。
【００２９】
金属−有機キレート化合物として具体的には透光性に影響のない亜鉛とβ−ジケトンよりなるアセチルアセトン亜鉛キレート、ベンゾイルアセトン亜鉛キレート、ジベンゾイルメタン亜鉛キレート、アセト酢酸エチル亜鉛キレートなどが挙げられる。特に亜鉛キレート化合物とすることにより優れた耐光性・耐熱性をエポキシ樹脂に付与することができる。また、亜鉛キレート化合物はエポキシ樹脂への選択的かつ穏やかな硬化促進作用を有するため脂環式エポキシ樹脂のような低分子量モノマーを主体としても低応力接着が可能となる。亜鉛キレート化合物は、扱い易さなどからアセチルアセトンをキレート成分としたビス（アセチルアセトナト）アクア亜鉛（2）[Ｚｎ（Ｃ5Ｈ7Ｏ2）2（Ｈ2Ｏ）]を１から１０重量部配合したものが好ましく、エポキシ樹脂への溶解性を考慮したならば１から５重量部がより好ましい。
【００３０】
芳香族スルホニウム塩は、組成物中に硬化剤である酸無水物を含まないエポキシ樹脂単独組成で使用される。芳香族スルホニウム塩は、熱及び／又は３６０ｎｍ以下の紫外光により分解しカチオンを発生、エポキシ樹脂カチオン重合硬化物を得ることができる。この得られた硬化物はエーテル架橋されており硬化剤硬化したものより物理、化学的により安定である。具体的には、トリフェニルスルホニウム六フッ化アンチモン塩、トリフェニルスルホニウム六フッ化りん塩などである。特にトリフェニルスルホニウム六フッ化アンチモン塩は硬化速度が速く少量配合でも十分硬化することからエポキシ樹脂１００重量部に対して０．０１から０．５重量部配合が好ましく、連鎖重合発熱による硬化物の変色を考慮したならば０．０５から０．３重量部配合がより好ましい。
【００３１】
（ＬＥＤチップ）本発明に用いられるＬＥＤチップは、比較的バンドエネルギーが高い半導体発光素子が挙げられる。このような半導体発光素子としては、ＭＯＣＶＤ法やＨＤＶＰＥ法等により形成された窒化物半導体が好適に用いられる。窒化物半導体は、ＩｎｘＡｌｙＧａ1-ｘ-ｙＮ（ただし、０≦ｘ、０≦ｙ、ｘ＋ｙ≦１）を発光層として利用させてある。半導体の構造としては、ＭＩＳ接合、ＰＩＮ接合やｐｎ接合などを有するホモ構造、ヘテロ構造あるいはダブルへテロ構成のものが挙げられる。半導体層の材料やその混晶度によって発光波長を種々選択することができる。また、半導体活性層を量子効果が生ずる薄膜に形成させた単一量子井戸構造や多重量子井戸構造とすることもできる。
【００３２】
窒化物半導体を形成させる基板にはサファイヤ、スピネル、ＳｉＣ、Ｓｉ、ＺｎＯ、窒化ガリウム系単結晶等の材料を用いることができる。結晶性の良い窒化ガリウム系半導体を量産性よく形成させるためにはサファイヤ基板を用いることが好ましく、サファイヤ基板との格子不整合を是正するためにバッファー層を形成することが望ましい。バッファー層は、低温で形成させた窒化アルミニウムや窒化ガリウムなどで形成させることができる。
【００３３】
窒化物半導体を使用したｐｎ接合を有する発光素子例として、バッファー層上に、ｎ型窒化ガリウムで形成した第１のコンタクト層、ｎ型窒化アルミニウム・ガリウムで形成させた第１のクラッド層、窒化インジウム・ガリウムで形成した活性層、ｐ型窒化アルミニウム・ガリウムで形成した第２のクラッド層、ｐ型窒化ガリウムで形成した第２のコンタクト層を順に積層させたダブルへテロ構成などが挙げられる。
【００３４】
なお、窒化物半導体は、不純物をドープしない状態でｎ型導電性を示す。発光効率を向上させるなど所望のｎ型窒化ガリウム半導体を形成させる場合は、ｎ型ドーパントとしてＳｉ、Ｇｅ、Ｓｅ、Ｔｅ、Ｃ等を適宜導入することが好ましい。一方、ｐ型窒化ガリウム半導体を形成させる場合は、ｐ型ドーパントであるＺｎ、Ｍｇ、Ｂｅ、Ｃａ、Ｓｒ、Ｂａ等をドープさせる。窒化ガリウム系化合物半導体は、ｐ型ドーパントをドープしただけではｐ型化しにくいためｐ型ドーパント導入後に、炉による加熱、低速電子線照射やプラズマ照射等により低抵抗化したｐ型とさせることが好ましい。
【００３５】
サファイアやスピネルなど絶縁性基板を用いた半導体発光素子の場合は、絶縁性基板の一部を除去する、或いは半導体表面側からｐ型及びｎ型用の電極面をとるためにｐ型半導体及びｎ型半導体の露出面をエッチングなどによりそれぞれ形成させる。各半導体層上にスパッタリング法や真空蒸着法などを用いて所望の形状の各電極を形成させる。発光面側に設ける電極は、全被覆せずに発光領域を取り囲むようにパターニングするか、或いは金属薄膜や金属酸化物などの透光性電極を用いることができる。このように形成された発光素子をそのまま利用することもできるし、個々に分割した発光素子として使用してもよい。
【００３６】
個々に分割された発光素子として利用する場合は、形成された半導体ウエハー等をダイヤモンド製の刃先を有するブレードが回転するダイシングソーにより直接フルカットするか、又は刃先幅よりも広い幅の溝を切り込んだ後（ハーフカット）、外力によって半導体ウエハーを割る。あるいは、先端のダイヤモンド針が往復直線運動するスクライバーにより半導体ウエハーに極めて細いスクライブライン（経線）を例えば碁盤目状に引いた後、外力によってウエハーを割り半導体ウエハーからチップ状にカットする。このようにして半導体発光素子であるＬＥＤチップなどを形成させることができる。次に、本発明における発光ダイオードについて具体的に説明するがこれのみに限られないことは言うまでもない。
【００３７】
【実施例】
（実施例１） ＬＥＤチップ１０２の発光層に青色が発光可能なＩｎ0.2Ｇａ0.8Ｎ半導体を有する窒化物半導体素子を用いた。より具体的にはＬＥＤチップは、洗浄させたサファイヤ基板上にＴＭＧ（トリメチルガリウム）ガス、ＴＭＩ（トリメチルインジウム）ガス、窒素ガス及びドーパントガスをキャリアガスと共に流し、ＭＯＣＶＤ法で窒化物半導体を成膜させることにより形成させることができる。ドーパントガスとしてＳｉＨ4とＣｐ2Ｍｇを切り替えることによってｎ型窒化物半導体やｐ型窒化物半導体となる層を形成させることができる。
【００３８】
ＬＥＤチップ１０２の素子構造としてはサファイア基板上に、アンドープの窒化物半導体であるｎ型ＧａＮ層、Ｓｉドープのｎ型電極が形成されｎ型コンタクト層となるＧａＮ層、アンドープの窒化物半導体であるｎ型ＧａＮ層、次に発光層を構成するバリア層となるＧａＮ層、井戸層を構成するＩｎＧａＮ層、バリア層となるＧａＮ層を１セットとしＧａＮ層に挟まれたＩｎＧａＮ層を５層積層させた多重量子井戸構造としてある。発光層上にはＭｇがドープされたｐ型クラッド層としてＡｌＧａＮ層、Ｍｇがドープされたｐ型コンタクト層であるＧａＮ層を順次積層させた構成としてある。（なお、サファイヤ基板上には低温でＧａＮ層を形成させバッファ層とさせてある。また、ｐ型半導体は、成膜後４００℃以上でアニールさせてある。）
エッチングによりサファイア基板上の窒化物半導体に同一面側で、ｐｎ各コンタクト層表面を露出させる。各コンタクト層上に、スパッタリング法を用いて正負各電極をそれぞれ形成させた。出来上がった半導体ウエハーをスクライブラインを引いた後、外力により分割させ発光素子であるＬＥＤチップを形成させた。このＬＥＤチップは４７０ｎｍに単色性ピーク波長を有するものであった。
【００３９】
表面に銀でメッキされた鉄入り銅から構成されるマウントリード１０５のカップ底面上に、ダイボンド樹脂１０３としてエポキシ樹脂組成物を利用してＬＥＤチップ１０２をダイボンドする。具体的には、先端カップ内にシリンジディスペンサーにより、エポキシ樹脂組成物を塗着しＬＥＤチップをマウントした。これを１７０℃で７５分加熱しエポキシ樹脂組成物を硬化させＬＥＤチップを固定した。
【００４０】
なお、ダイボンド樹脂１０３は種々のものを利用することができるものの、より信頼性の高いエポキシ樹脂組成物として非芳香族エポキシ樹脂である３，４エポキシシクロメチル−３′，４′エポキシシクロヘキシルカルボキシレート１００重量部、メチルヘキサヒドロ無水フタル酸９０重量部、エチレングリコール１０重量部、オクチル酸亜鉛４重量部、ビス（アセチルアセトナト）アクア亜鉛（2）２．５重量部を混合し均一な無色透明なエポキシ樹脂組成物を用いて構成してある。
【００４１】
次に、ＬＥＤチップ１０２の正負各電極と、マウントリード１０５及びインナーリード１０６とを金線１０４によりワイヤーボンディングさせ電気的導通を取った。
【００４２】
続いて、主剤となる脂環式エポキシ樹脂からなる３，４エポキシシクロメチル−３′，４′エポキシシクロヘキシルカルボキシレート１００重量部、硬化剤となるメチルヘキサヒドロフタル酸無水物１２５重量部、助触媒として働くエチレングリコール５重量部及びベンジルトリフェニルホスホニウム臭素塩０．２重量部の割合で混合し、無色透明なエポキシ樹脂組成物を形成させた。
【００４３】
こうして混合されたエポキシ樹脂組成物を砲弾型の型枠であるキャスティングケース内に注入させる。上述のＬＥＤチップがカップ内に配置されたマウントリード及びインナーリードの一部をキャスティングケース内に挿入し１２０℃２時間の一次硬化を行った。一次硬化後、キャスティングケースから発光ダイオードを抜き出し、窒素雰囲気下において１８０℃５時間で二次硬化を行った。これにより本発明の透光性樹脂１０１でモールドされた出力約６ｍＷの発光ダイオードを形成させることができる。また、形成された透光性樹脂を加水分解させて、液体クロマトグラフィで定量分析させた。その結果、フェノール誘導体エポキシ樹脂がエポキシ樹脂組成物中に含有されていないことを確認した。
【００４４】
（実施例２） 透光性モールド樹脂として含窒素エポキシ樹脂からなるトリグリシジルイソシアヌレート１００重量部、硬化剤となるメチルヘキサフタル酸無水物１７０重量部、助触媒として働くエチレングリコール５重量部を混合させた無色透明なエポキシ樹脂組成物を用いた以外は実施例１と同様にして発光ダイオードを形成させる。なお、硬化条件は注型法により１２０℃で２時間の一次硬化後脱型し、窒素雰囲気下にて１８０℃で１０時間二次硬化を行った。また、フェノール誘導体エポキシ樹脂がエポキシ樹脂中に含有されていないことを確認した。
【００４５】
（実施例３） ＬＥＤチップとして井戸層を構成するＩｎの含有量を変化させて主発光スペクトルピークを約３９５ｎｍから約５４５ｎｍまで、ほぼ１０ｎｍづつ変化させたＬＥＤチップを１６種類形成させる。他方、モールド樹脂として主剤となる脂環式エポキシ樹脂からなる３，４エポキシシクロメチル−３′，４′エポキシシクロヘキシルカルボキシレート９０重量部、ビスフェノールＡジグリシジルエーテル１０重量部、硬化剤となるメチルヘキサヒドロフタル酸無水物１２５重量部、助触媒として働くエチレングリコール５重量部及びベンジルトリフェニルホスホニウム臭素塩０．２重量部の割合で混合させた無色透明なエポキシ樹脂組成物を用いた以外は実施例１と同様にして発光ダイオードを形成させる。なお、硬化条件は注型法により１２０℃で２時間の一次硬化後脱型し、窒素雰囲気下にて１８０℃で５時間二次硬化を行った。また、フェノール誘導体エポキシ樹脂がエポキシ樹脂組成物の約４％であることを確認した。こうして形成された発光ダイオードは短波長ほど劣化しやすかったものの実施例１とほぼ同様の特性を示す。
【００４６】
（比較例１）
モールド樹脂としてビスフェノールＡジグリシジルエーテル１００重量部、メチルヘキサヒドロフタル酸無水物９０重量部、エチレングリコール５重量部、ベンジルトリフェニルホスホニウム臭素塩０．２重量部を混合させたエポキシ樹脂組成物とした以外は実施例１と同様にして発光ダイオードを形成させる。なお、硬化条件は注型法により１２０で２時間の一次硬化後脱型し、窒素雰囲気中にて１３０℃で３時間二次硬化を行った。また、形成された透光性樹脂を加水分解させて、液体クロマトグラフィで定量分析させた。その結果、フェノール誘導体エポキシ樹脂が約５１％であることを確認した。
【００４７】
（比較例２）
ＬＥＤチップを被覆する透光性樹脂としてビスフェノールＡジグリシジルエーテル２５重量部、３，４エポキシシクロメチル−３′，４′エポキシシクロヘキシルカルボキシレート７５重量部、メチルヘキサヒドロフタル酸無水物１２０重量部、エチレングリコール５重量部、ベンジルトリフェニルホスホニウム臭素塩０．２重量部を混合させたエポキシ樹脂組成物とした以外は実施例１と同様にして発光ダイオードを形成させる。なお、硬化条件は注型法により１２０で２時間の一次硬化後脱型し、窒素雰囲気中にて１５０℃で５時間二次硬化を行った。また、フェノール誘導体エポキシ樹脂がエポキシ樹脂組成物の約１１％であることを確認した。
【００４８】
形成させた実施例１、実施例２及び比較例１の発光ダイオードの通電時における信頼性を調べた。その結果を図２及び図３に示す。図２（Ａ）は、６０ｍＡ通電時の初期相対パワーと通電時間を実施例１（実線）、実施例２（鎖線）及び比較例１（一点鎖線）で表したグラフである。さらに、図２（Ｂ）は８５℃／８５％ＲＨ、１０ｍＡの条件で、初期相対パワーと通電時間を実施例１（実線）、実施例２（鎖線）及び比較例１（一点鎖線）で表したグラフである。また図３に実施例１（実線）、実施例２（鎖線）、比較例１（一点鎖線）及び比較例２（二点鎖線）の発光ダイオードのウエザーメーターにおける耐候性評価を透光性樹脂部の正面透過率と試験経過時間で表したグラフで示す。なお、ウエザーメーターの試験条件はキセノンランプで照射強度１８０Ｗ／ｍ２（４００ｎｍ以下トータル）、試料表面温度６３℃、湿度５０％で照射４８分及び降雨及び照射１２分を１サイクルとして行った。これにより、通電時における発光ダイオードの信頼性と透光性樹脂部の耐候性には明らかに相関があることがわかる。
【００４９】
これより、エポキシ樹脂組成物中における１０％以上の芳香族エポキシ成分の存在が発光ダイオードの劣化に大きな影響を与えていることがわかる。以上の結果から、本発明の発光ダイオードが比較のための発光ダイオードと比べて経時劣化の少ない発光ダイオードとすることができることがわかる。なお、本発明の透光性樹脂はより長波長を発光可能な発光素子を封止するために利用することもできる。
【００５０】
【発明の効果】
本発明は５５０ｎｍ以下の短波長、高出力の発光素子を樹脂によって被覆した発光ダイオードにおいても、量産性よく信頼性の高い発光ダイオードとすることができる。
【００５１】
【図面の簡単な説明】
【図１】本発明の発光ダイオードを示す模式的断面図である。
【００５２】
【図２】本発明の発光ダイオードと比較のために示した発光ダイオードとの６０ｍＡ通電時の初期相対パワーと通電時間を表したグラフである。
【００５３】
【図３】本発明の発光ダイオードと比較のために示した発光ダイオードとの耐候性試験を表したグラフである。
【００５４】
【図４】本発明と比較のために示す発光ダイオードの模式的断面図である。
【００５５】
【符号の説明】
１０１・・・モールド樹脂となる透光性樹脂
１０２・・・発光素子となるＬＥＤチップ
１０３・・・ダイボンド樹脂
１０４・・・ワイヤ
１０５・・・マウントリード
１０６・・・インナーリード
４０１・・・モールド樹脂となる透光性樹脂
４０２・・・発光素子となるＬＥＤチップ
４０３・・・ダイボンド樹脂
４０４・・・ワイヤ
４０５・・・マウントリード
４０６・・・インナーリード[0001]
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to light emitting diodes used for various indicators, LED displays, backlight light sources, and the like, and more particularly to a light emitting diode that is highly reliable and has little change with time.
[0002]
[Prior art]
Today, light emitting diodes capable of emitting more than 1000 mcd have been developed for both RGB and are being used in various fields. An example of such a light emitting diode is shown in FIG. FIG. 4 is a schematic cross-sectional view of the light emitting diode.
[0003]
In the figure, a mount lead 405 having a cup serving as a lead electrode and an inner lead 406 are provided. An LED chip 402 is mounted on the cup of the mount lead using a die bond resin 403. In order to electrically connect the electrode of the LED chip and the inner lead 406, the inner lead and the wire are bonded by a wire 404. On the other hand, the other electrode of the LED chip and the mount lead 405 are electrically connected by Ag paste. Thus, the LED chip and the wire electrically connected to the lead electrode are molded with a translucent resin 401 for the purpose of protecting from the external environment.
[0004]
The translucent resin 401 serving as a mold resin is made to inject an epoxy resin into a casting case that is a mold that can obtain a desired shape, such as a cannonball mold in advance. A part of the LED chip and the lead electrode is inserted and fixed to the epoxy resin injected into the mold. In this state, the epoxy resin is cured. After curing, the light emitting diode can be formed by removing it from the casting case. As a result, it is possible to protect the LED chip with a relatively simple configuration and to construct a light emitting diode that can efficiently obtain desired light distribution characteristics and the like.
[0005]
In particular, as a characteristic of a mold resin used for a light emitting diode, 1. Excellent adhesion to lead frame, LED chip, etc. High mechanical strength and excellent impact resistance,3. 3. The mold dimension design is easy and the stress is low and the LED chip is not easily damaged by the stress at the time of formation. 4. It has excellent low shrinkage and easy removal from the mold. There is very little deformation caused by heat above the Tg (glass transition point) that occurs when mounted on a circuit board with solder or during driving.6. Void-free and low viscosity that is less likely to cause bubbles, etc., and7. As one of the most important items as a light emitting diode, it is required to have excellent translucency with respect to light emitted from the LED chip. Due to such characteristics peculiar to the light emitting diode, it is preferable to use an epoxy resin as the mold member.
[0006]
Examples of the epoxy resin mold member include those using bisphenol-type epoxy resin or bisphenol-type urethane-modified epoxy resin as the main constituent resin as disclosed in JP-A-6-316626. Phenolic epoxy resins represented by bisphenol A diglycidyl ether satisfy the above-mentioned characteristics and are particularly excellent in translucency in visible light.
[0007]
On the other hand, with the rapid progress of today's light emitting diode technology, higher output and shorter wavelength of LED chips are rapidly becoming a reality. Specifically, an LED using a nitride semiconductor can emit light with an arbitrary emission peak having a main emission peak of about 365 nm to 650 nm depending on elements constituting the composition of the emission layer, and particularly visible light (specifically, 550 nm or less). It is possible to form a high-efficiency LED chip relatively easily even with near-ultraviolet light to blue-green light. Further, by using a multiple quantum well structure for the light emitting layer of the nitride semiconductor, a light emitting diode capable of emitting a high output of 5 mW or more can be obtained.
[0008]
[Problems to be solved by the invention]
However, simply sealing an LED chip capable of emitting light with a shorter wavelength and higher output with the above-described epoxy resin or the like has a new problem in that the emission luminance due to the deterioration of the resin decreases with time. Arise. More specifically, light emission using an LED chip that mainly uses bisphenol A diglycidyl ether as an epoxy resin that satisfies the characteristics of a light emitting diode mold resin, and emits light from green to red with relatively low energy. In the diode, the mold resin is hardly deteriorated only by the light emitted from the LED chip, and it is possible to emit light efficiently.
[0009]
However, in an LED chip that emits a main light emission peak at 550 nm or less, which is the short wavelength side of visible light, the luminance rapidly decreases over time even when formed in the same manner as a light emitting diode capable of emitting long wavelengths of visible light. Accordingly, the present invention is to provide a light emitting diode that satisfies the characteristics required for the mold resin of the above light emitting diode and that has very little temporal change even when a specific LED chip is used, and that has excellent light utilization efficiency.
[0010]
[Means for Solving the Problems]
The light-emitting diode of the present invention is a light-emitting diode having at least a light-emitting element electrically connected to a pair of lead electrodes and a light-transmitting resin that covers the light-emitting element, and the light-emitting element has a near ultraviolet wavelength of 550 nm or less. It has a light emitting layer that emits a main light emission peak from light to visible light, and the translucent resin is an epoxy resin composition having a phenol derivative epoxy resin of less than 10%, and the epoxy resin composition is contained in 100 parts by weight of the epoxy resin. On the other hand, (a) 50 to 150 parts by weight of a polybasic acid carboxylic acid anhydride not chemically having a carbon double bond,(B) 1 to 30 parts by weight of an alcohol / polyol of any one of a linear type, a branched type, an alicyclic type, and an ether group-containing type having 2 to 12 carbon atoms that are non-aromatic and have no carbon double bond (C) 0.01 to 1 part by weight of phosphines and / or quaternary salts thereof, or 1 to 10 parts by weight of an organic carboxylic acid metal salt having no carbon double bond, Including,Reduces yellowing due to deterioration over timeThis is a light emitting diode characterized by the above. As a result, it is possible to obtain a light-emitting diode that is excellent in mass productivity and has little light deterioration while satisfying translucency.Moreover, flexibility is given to hardened | cured material by adding alcohol and polyols which work as a co-catalyst to an epoxy resin composition, and it can improve peeling adhesive force. In addition, alcohols and polyols that function as cocatalysts also function as compatibilizers such as phosphines and organic carboxylic acid metal salts that function as curing accelerators, and exhibit functions such as organic carboxylic acid metal salts that function as curing accelerators. Further, the curability can be improved.
[0011]
A light-emitting diode according to claim 2 of the present invention is a light-emitting diode having a light-emitting element electrically connected to at least a pair of lead electrodes, and a translucent resin that covers the light-emitting element. Is a nitride semiconductor containing at least In and Ga in which the light emitting layer emits a main light emission peak at 550 nm or less, and the epoxy resin of the translucent resin is a non-aromatic epoxy resin composition of 90% or more, The epoxy resin composition comprises (a) 50 to 150 parts by weight of a polybasic acid carboxylic acid anhydride that does not have a carbon double bond chemically with respect to 100 parts by weight of the epoxy resin.(B) 1 to 30 weights of alcohols / polyols of any one of straight chain type, branched type, alicyclic type, and ether group-containing type having 2 to 12 carbon atoms that are non-aromatic and have no carbon double bond Parts, (c) 0.01 to 1 part by weight of phosphines and / or quaternary salts thereof, or 1 to 10 parts by weight of an organic carboxylic acid metal salt having no carbon double bond, Including,Reduces yellowing due to deterioration over timeThis is a light emitting diode characterized by the above. As a result, it is possible to obtain a light-emitting diode that is excellent in mass productivity and has little light deterioration while satisfying translucency.Moreover, flexibility is given to hardened | cured material by adding alcohol and polyols which work as a co-catalyst to an epoxy resin composition, and it can improve peeling adhesive force. In addition, alcohols and polyols that function as cocatalysts also function as compatibilizers such as phosphines and organic carboxylic acid metal salts that function as curing accelerators, and exhibit functions such as organic carboxylic acid metal salts that function as curing accelerators. Further, the curability can be improved.
[0012]
In the light-emitting diode according to the present invention, the non-aromatic epoxy resin composition is an alicyclic epoxy resin and / or a nitrogen-containing epoxy resin.Is preferred. Thereby, a highly reliable light emitting diode can be formed more simply.
[0013]
By using the light-emitting diode according to the present invention, the alicyclic epoxy resin is at least one selected from cyclohexene epoxidized derivative, hydrogenated bisphenol A diglycidyl ether, hexahydrophthalic acid glycidyl ester, and nitrogen-containing epoxy resin. is thereIs preferred. Thereby, a highly reliable light emitting diode can be formed more simply.
[0014]
In the light emitting diode according to the present invention, the nitrogen-containing epoxy resin is triglycidyl isocyanurate.Is preferred. Thereby, a highly reliable light emitting diode can be formed more simply.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
As a result of various experiments, the present inventor has a relatively simple configuration and a highly reliable light-emitting diode by sealing an LED chip that emits light from a short wavelength of visible light to an ultraviolet region with a specific epoxy resin. The present invention has been found out.
[0016]
That is, a translucent resin that coats an LED chip that emits high power on the short wavelength side of visible light from the near-ultraviolet region (in this specification, it is assumed that it is 365 nm or more capable of emitting light from a nitride semiconductor). The resin rapidly deteriorates due to light and heat emitted from the LED chip itself from the vicinity of the interface. In particular, in a light-emitting diode using an aromatic epoxy resin having a carbon-carbon double bond as a translucent resin, once the double bond is broken and oxidized by light or heat energy from the LED chip, Causes discoloration.
[0017]
Yellowing coloring not only simply colors the resin, but also has a complementary color relationship or near complementary color with respect to visible light of 550 nm or less, particularly blue. Therefore, it can be considered that the light from the LED chip is easily absorbed and deterioration is promoted. In addition, when a nitride semiconductor such as a multiple quantum well structure capable of emitting a high-power light having a short wavelength of visible light of 5 mW or more from the near ultraviolet region is used, it tends to appear remarkably.
[0018]
The present inventor has translucent epoxy resin composition mainly composed of non-aromatic epoxy resin not having double bond between carbon and carbon which causes deterioration while having characteristics of translucent resin used for light emitting diode. Selected as a functional resin. Thereby, although the initial visible light transmittance is slightly lowered, deterioration from the LED chip caused by sealing the LED chip can be prevented, and a highly reliable light emitting diode can be obtained without causing deterioration over time. Hereinafter, the configuration of the present invention will be described in detail.
[0019]
(Translucent resin) The epoxy resin composition of the present invention to be a translucent resin covers an LED chip. Therefore, since high light resistance, insulation, and translucency are required, it is preferable that the aromatic component that causes coloring, particularly the phenol derivative epoxy resin, is less than 10 wt% in the composition, more preferably less than 5%. It is. In addition, what does not contain a phenol derivative epoxy resin at all will have the most excellent light resistance. Moreover, 90% or more is preferable as an epoxy component in a non-aromatic epoxy resin in an epoxy resin composition, More preferably, it is 95% or more. An epoxy resin that can have an inorganic chlorine content of 1 ppm or less and an organic chlorine content of 5 ppm or less is preferred. In particular, those produced by distillation and containing no chlorine component are more preferred.
[0020]
Specifically, alicyclic epoxy resins represented by 3,4 epoxycyclohexylmethyl-3 ′, 4 ′ epoxycyclohexyl carboxylate can be used alone or in admixture of two or more. In addition, cycloaliphatic epoxy resin mainly composed of hexahydrophthalic acid diglycidyl ester, cyclohexane derivative such as hydrogenated bisphenol A diglycidyl ether and epoxy resin composed of epichlorohydrin, liquid or solid epoxy resin composed of bisphenol A diglycidyl ether, etc. Can also be mixed and used if necessary. Similarly, triglycidyl isocyanurate can be mentioned as a nitrogen-containing epoxy resin. Moreover, this epoxy resin composition of this invention can be made into various shapes according to the form of a light emitting diode. Moreover, various fluorescent substances, diffusing agents, and coloring agents can be included as desired. In addition to the above-mentioned epoxy resin, the epoxy resin composition can be appropriately mixed with the following curing agent, promoter and curing accelerator.
[0021]
(Curing agent) The acid anhydride suitably contained in the epoxy resin composition is a kind of polybasic acid carboxylic acid anhydride which is non-aromatic and chemically does not have a carbon double bond because it requires light resistance or Two or more are preferred. Specific examples include hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, trialkyltetrahydrophthalic anhydride, and hydrogenated methylnadic acid anhydride.
[0022]
In particular, 50 to 150 parts by weight of methylhexahydrophthalic anhydride having a good balance between curing reactivity and moisture resistance as an acid anhydride is preferably added to 100 parts by weight of epoxy resin, and 80 to 130 parts by weight is preferably added. More preferred.
[0023]
(Cocatalyst) The cocatalyst is suitably contained in the epoxy resin composition. Alcohols and polyols that act as co-catalysts not only give flexibility to the cured product and improve the peel adhesion, but also function as a compatibilizer for the curing accelerator described later. Alcohols and polyols are also required to have light resistance, so they are non-aromatic and do not have a carbon double bond in chemical structure. They are straight-chain, branched, alicyclic, or ether group-containing types having 2 to 12 carbon atoms. Such alcohols and polyols are preferably used. Specific examples include propanol, isopropanol, methylcyclohexanol, ethylene glycol, glycerin, trimethylolpropane, and ethylene glycol monomethyl ether.
[0024]
Alcohols and polyols are also compatibilizers for curing accelerators, and are affected by the chemical structure and blending amount of the curing accelerator, but are preferably blended in a small amount of 1 to 30 parts by weight of a low molecular weight diol such as ethylene glycol, More preferred is 5 to 15 parts by weight.
[0025]
(Curing Accelerator) The curing accelerator is suitably contained in the epoxy resin composition. As the curing accelerator, 1. Tertiary amines or imidazoles and / or their organic carboxylates; 2. 2. phosphines and / or quaternary salts thereof; 3. organic carboxylic acid metal salt; 4. metal-organic chelate compounds; An aromatic sulfonium salt is mentioned, It can use individually or in mixture of 2 or more types.
[0026]
Specific examples of tertiary amines, imidazoles and their organic carboxylates include 2,4,6-tris (diaminomethyl) phenol, 2-ethyl-4-methylimidazole, 1,8-diazabiscyclo (5,5). 4,0) Undecene-7 (hereinafter DBU) and its octylate. In particular, DBU octylate, which is excellent in translucency of the cured product, is preferably blended in an amount of 0.01 to 1 part by weight with respect to 100 parts by weight of the epoxy resin. More preferably, 5 parts by weight is blended.
[0027]
Specific examples of phosphines and quaternary salts thereof include triphenylphosphine, tributylphosphine, benzyltriphenylphosphonium bromine salt, and benzyltributylphosphonium bromine salt. In particular, it is preferable to blend 0.01 to 1 part by weight of benzyltriphenylphosphonium bromine salt, which is excellent in translucency of the cured product, with respect to 100 parts by weight of the epoxy resin. More preferred is a blend of ˜0.5 parts by weight.
[0028]
Specific examples of the organic carboxylic acid metal salt include zinc octylate, zinc laurate, zinc stearate, tin octylate and the like that do not have a carbon double bond inferior in light resistance. The organic carboxylic acid metal salt is in proportion to the increase in the carbon number of the organic carboxylic acid component, and the solubility in the epoxy resin decreases. Zinc octylate has the widest blending amount, and since it is liquid, it does not require time for dispersion and dissolution. Therefore, it is preferable to blend 1 to 10 parts by weight of zinc octylate from the viewpoint of curability. Considering the translucency of the cured product, 1 to 5 parts by weight is more preferable.
[0029]
Specific examples of the metal-organic chelate compound include acetylacetone zinc chelate, benzoylacetone zinc chelate, dibenzoylmethane zinc chelate, and ethyl zinc acetoacetate chelate composed of zinc and β-diketone which do not affect translucency. In particular, by using a zinc chelate compound, excellent light resistance and heat resistance can be imparted to the epoxy resin. In addition, since the zinc chelate compound has a selective and gentle curing accelerating action on the epoxy resin, low-stress adhesion is possible even with a low molecular weight monomer such as an alicyclic epoxy resin as a main component. The zinc chelate compound is preferably an epoxy compound containing 1 to 10 parts by weight of bis (acetylacetonato) aquazinc (2) [Zn (C5H7O2) 2 (H2O)] containing acetylacetone as a chelate component for ease of handling. Considering solubility in the resin, 1 to 5 parts by weight is more preferable.
[0030]
The aromatic sulfonium salt is used in an epoxy resin single composition that does not contain an acid anhydride as a curing agent in the composition. The aromatic sulfonium salt is decomposed by heat and / or ultraviolet light of 360 nm or less to generate cations, and an epoxy resin cationic polymerization cured product can be obtained. The obtained cured product is ether-crosslinked and is more physically and chemically more stable than the cured product of the curing agent. Specific examples include triphenylsulfonium hexafluoride antimony salt and triphenylsulfonium hexafluoride phosphorous salt. In particular, triphenylsulfonium hexafluoride antimony salt has a high curing rate and can be sufficiently cured even in a small amount, so that 0.01 to 0.5 parts by weight is preferable with respect to 100 parts by weight of the epoxy resin. In consideration of discoloration, 0.05 to 0.3 parts by weight is more preferable.
[0031]
(LED chip) The LED chip used in the present invention includes a semiconductor light emitting device having a relatively high band energy. As such a semiconductor light emitting element, a nitride semiconductor formed by MOCVD method, HDVPE method or the like is preferably used. The nitride semiconductor uses InxAlyGa1-xyN (where 0 ≦ x, 0 ≦ y, x + y ≦ 1) as the light emitting layer. Examples of the semiconductor structure include a homostructure having a MIS junction, a PIN junction, and a pn junction, a heterostructure, and a double heterostructure. Various emission wavelengths can be selected depending on the material of the semiconductor layer and the degree of mixed crystal. In addition, a single quantum well structure or a multiple quantum well structure in which the semiconductor active layer is formed in a thin film in which a quantum effect is generated can be used.
[0032]
For the substrate on which the nitride semiconductor is formed, materials such as sapphire, spinel, SiC, Si, ZnO, and gallium nitride single crystal can be used. A sapphire substrate is preferably used in order to form a gallium nitride semiconductor having good crystallinity with high productivity, and a buffer layer is preferably formed in order to correct lattice mismatch with the sapphire substrate. The buffer layer can be formed of aluminum nitride or gallium nitride formed at a low temperature.
[0033]
As an example of a light emitting device having a pn junction using a nitride semiconductor, a first contact layer formed of n-type gallium nitride, a first cladding layer formed of n-type aluminum nitride / gallium on a buffer layer, nitrided Examples include a double hetero structure in which an active layer formed of indium gallium, a second cladding layer formed of p-type aluminum nitride / gallium, and a second contact layer formed of p-type gallium nitride are sequentially stacked.
[0034]
Note that the nitride semiconductor exhibits n-type conductivity without being doped with impurities. When forming a desired n-type gallium nitride semiconductor such as improving luminous efficiency, it is preferable to appropriately introduce Si, Ge, Se, Te, C, etc. as an n-type dopant. On the other hand, when a p-type gallium nitride semiconductor is formed, a p-type dopant such as Zn, Mg, Be, Ca, Sr, or Ba is doped. Since the gallium nitride compound semiconductor is difficult to become p-type only by doping with a p-type dopant, it is preferable that the p-type dopant is reduced to p-type by heating in a furnace, low-energy electron beam irradiation, plasma irradiation, or the like after introduction of the p-type dopant. .
[0035]
In the case of a semiconductor light emitting device using an insulating substrate such as sapphire or spinel, the p-type semiconductor and n are used to remove a part of the insulating substrate or to take p-type and n-type electrode surfaces from the semiconductor surface side. Each exposed surface of the mold semiconductor is formed by etching or the like. Each electrode having a desired shape is formed on each semiconductor layer by using a sputtering method, a vacuum deposition method, or the like. The electrode provided on the light emitting surface side may be patterned so as to surround the light emitting region without being completely covered, or a light transmitting electrode such as a metal thin film or a metal oxide can be used. The light emitting elements formed in this way can be used as they are, or can be used as individually divided light emitting elements.
[0036]
When used as individually divided light emitting elements, the formed semiconductor wafer or the like is directly fully cut by a dicing saw with a blade having a diamond cutting edge or a groove having a width wider than the cutting edge width is cut. After that (half cut), the semiconductor wafer is broken by external force. Alternatively, after a very thin scribe line (meridian) is drawn on the semiconductor wafer by, for example, a grid pattern by a scriber in which the diamond needle at the tip moves reciprocally linearly, the wafer is divided by external force and cut into chips. Thus, an LED chip or the like that is a semiconductor light emitting element can be formed. Next, the light emitting diode in the present invention will be described in detail, but it is needless to say that the present invention is not limited thereto.
[0037]
【Example】
Example 1 A nitride semiconductor element having an In 0.2 Ga 0.8 N semiconductor capable of emitting blue light was used for the light emitting layer of the LED chip 102. More specifically, in the LED chip, TMG (trimethylgallium) gas, TMI (trimethylindium) gas, nitrogen gas and dopant gas are flowed together with a carrier gas on a cleaned sapphire substrate, and a nitride semiconductor is formed by MOCVD. Can be formed. By switching between SiH4 and Cp2Mg as the dopant gas, a layer that becomes an n-type nitride semiconductor or a p-type nitride semiconductor can be formed.
[0038]
The element structure of the LED chip 102 is an n-type GaN layer which is an undoped nitride semiconductor on a sapphire substrate, a GaN layer where an Si-doped n-type electrode is formed to become an n-type contact layer, and an undoped nitride semiconductor. The n-type GaN layer, then the GaN layer that will be the barrier layer that constitutes the light emitting layer, the InGaN layer that constitutes the well layer, and the GaN layer that will be the barrier layer are set as one set, and five InGaN layers sandwiched between the GaN layers are laminated. It has a multi-quantum well structure. On the light emitting layer, an AlGaN layer as a p-type cladding layer doped with Mg and a GaN layer as a p-type contact layer doped with Mg are sequentially laminated. (Note that a GaN layer is formed on the sapphire substrate at a low temperature to serve as a buffer layer. The p-type semiconductor is annealed at 400 ° C. or higher after film formation.)
Etching exposes the surface of each pn contact layer on the same side as the nitride semiconductor on the sapphire substrate. Positive and negative electrodes were formed on each contact layer by sputtering. After drawing the scribe line on the completed semiconductor wafer, it was divided by an external force to form LED chips as light emitting elements. This LED chip had a monochromatic peak wavelength at 470 nm.
[0039]
The LED chip 102 is die-bonded using an epoxy resin composition as the die-bonding resin 103 on the cup bottom surface of the mount lead 105 made of iron-containing copper plated with silver on the surface. Specifically, the epoxy resin composition was applied to the tip cup with a syringe dispenser, and the LED chip was mounted. This was heated at 170 ° C. for 75 minutes to cure the epoxy resin composition and fix the LED chip.
[0040]
Although various types of die bond resin 103 can be used, 3,4 epoxycyclomethyl-3 ′, 4 ′ epoxycyclohexyl carboxylate, which is a non-aromatic epoxy resin, as a more reliable epoxy resin composition. 100 parts by weight, 90 parts by weight of methylhexahydrophthalic anhydride, 10 parts by weight of ethylene glycol, 4 parts by weight of zinc octylate and 2.5 parts by weight of bis (acetylacetonato) aquazinc (2) are mixed and are uniformly colorless and transparent The epoxy resin composition is used.
[0041]
Next, the positive and negative electrodes of the LED chip 102, the mount lead 105, and the inner lead 106 were wire-bonded with a gold wire 104 to establish electrical continuity.
[0042]
Subsequently, 100 parts by weight of 3,4 epoxycyclomethyl-3 ', 4' epoxycyclohexylcarboxylate composed of an alicyclic epoxy resin as a main agent, 125 parts by weight of methylhexahydrophthalic anhydride as a curing agent, and a promoter As a mixture, 5 parts by weight of ethylene glycol and 0.2 part by weight of benzyltriphenylphosphonium bromine salt were mixed to form a colorless and transparent epoxy resin composition.
[0043]
The epoxy resin composition thus mixed is poured into a casting case which is a shell-shaped mold. A part of the mount lead and the inner lead in which the above-described LED chip is disposed in the cup was inserted into the casting case, and primary curing was performed at 120 ° C. for 2 hours. After the primary curing, the light emitting diode was extracted from the casting case and subjected to secondary curing at 180 ° C. for 5 hours in a nitrogen atmosphere. Thereby, a light emitting diode with an output of about 6 mW molded with the translucent resin 101 of the present invention can be formed. Moreover, the formed translucent resin was hydrolyzed and quantitatively analyzed by liquid chromatography. As a result, it was confirmed that the phenol derivative epoxy resin was not contained in the epoxy resin composition.
[0044]
(Example 2) Mixing 100 parts by weight of triglycidyl isocyanurate composed of a nitrogen-containing epoxy resin as a translucent mold resin, 170 parts by weight of methylhexaphthalic anhydride serving as a curing agent, and 5 parts by weight of ethylene glycol serving as a promoter. A light emitting diode is formed in the same manner as in Example 1 except that the colorless and transparent epoxy resin composition is used. The curing conditions were a casting method followed by demolding after primary curing at 120 ° C. for 2 hours, and secondary curing was performed at 180 ° C. for 10 hours in a nitrogen atmosphere. Moreover, it confirmed that the phenol derivative epoxy resin was not contained in the epoxy resin.
[0045]
(Example 3) As the LED chip, 16 types of LED chips were formed by changing the content of In constituting the well layer and changing the main emission spectrum peak from about 395 nm to about 545 nm by about 10 nm. On the other hand, 90 parts by weight of 3,4 epoxycyclomethyl-3 ', 4'epoxycyclohexylcarboxylate composed of alicyclic epoxy resin as a main resin as mold resin, 10 parts by weight of bisphenol A diglycidyl ether, methylhexa as a curing agent Except for using a colorless and transparent epoxy resin composition mixed in a proportion of 125 parts by weight of hydrophthalic anhydride, 5 parts by weight of ethylene glycol serving as a co-catalyst and 0.2 parts by weight of benzyltriphenylphosphonium bromine salt In the same manner as in No. 1, a light emitting diode is formed. The curing conditions were a casting method followed by demolding after primary curing at 120 ° C. for 2 hours, and secondary curing was performed at 180 ° C. for 5 hours in a nitrogen atmosphere. It was also confirmed that the phenol derivative epoxy resin was about 4% of the epoxy resin composition. The light-emitting diode formed in this way is more likely to deteriorate as the wavelength is shorter, but exhibits substantially the same characteristics as in Example 1.
[0046]
(Comparative Example 1)
An epoxy resin composition was prepared by mixing 100 parts by weight of bisphenol A diglycidyl ether, 90 parts by weight of methylhexahydrophthalic anhydride, 5 parts by weight of ethylene glycol, and 0.2 parts by weight of benzyltriphenylphosphonium bromide as a mold resin. A light emitting diode is formed in the same manner as in Example 1 except for the above. The curing was carried out by a casting method at 120 for 2 hours and then demolded, followed by secondary curing at 130 ° C. for 3 hours in a nitrogen atmosphere. Moreover, the formed translucent resin was hydrolyzed and quantitatively analyzed by liquid chromatography. As a result, it was confirmed that the phenol derivative epoxy resin was about 51%.
[0047]
(Comparative Example 2)
25 parts by weight of bisphenol A diglycidyl ether, 75 parts by weight of 3,4 epoxycyclomethyl-3 ′, 4 ′ epoxycyclohexyl carboxylate, 120 parts by weight of methylhexahydrophthalic anhydride, as a translucent resin for coating the LED chip A light emitting diode is formed in the same manner as in Example 1 except that an epoxy resin composition in which 5 parts by weight of ethylene glycol and 0.2 parts by weight of benzyltriphenylphosphonium bromide are mixed is used. The curing was carried out by a casting method at 120 for 2 hours followed by primary curing, followed by demolding and secondary curing at 150 ° C. for 5 hours in a nitrogen atmosphere. It was also confirmed that the phenol derivative epoxy resin was about 11% of the epoxy resin composition.
[0048]
The reliability of the formed light emitting diodes of Example 1, Example 2 and Comparative Example 1 when energized was examined. The results are shown in FIGS. FIG. 2A is a graph showing the initial relative power and energization time during energization of 60 mA in Example 1 (solid line), Example 2 (chain line), and Comparative Example 1 (dashed line). Further, FIG. 2B shows the initial relative power and energization time in the conditions of 85 ° C./85% RH and 10 mA in Example 1 (solid line), Example 2 (chain line), and Comparative Example 1 (one-dot chain line). It is a graph. 3 shows the weather resistance evaluation in the weather meter of the light emitting diodes of Example 1 (solid line), Example 2 (chain line), Comparative Example 1 (one-dot chain line) and Comparative Example 2 (two-dot chain line). It shows with the graph represented by the front transmittance of and test elapsed time. The test conditions of the weather meter were a xenon lamp with an irradiation intensity of 180 W / m 2 (total of 400 nm or less), a sample surface temperature of 63 ° C., a humidity of 50%, and irradiation for 48 minutes and rainfall and irradiation for 12 minutes. Thus, it can be seen that there is a clear correlation between the reliability of the light emitting diode during energization and the weather resistance of the translucent resin portion.
[0049]
From this, it can be seen that the presence of 10% or more of the aromatic epoxy component in the epoxy resin composition has a great influence on the deterioration of the light emitting diode. From the above results, it can be seen that the light-emitting diode of the present invention can be a light-emitting diode with little deterioration over time as compared with the light-emitting diode for comparison. The translucent resin of the present invention can also be used for sealing a light emitting element capable of emitting longer wavelengths.
[0050]
【The invention's effect】
The present invention can provide a light-emitting diode with high productivity and high reliability even in a light-emitting diode in which a light-emitting element with a short wavelength of 550 nm or less and a high output is coated with a resin.
[0051]
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a light emitting diode of the present invention.
[0052]
FIG. 2 is a graph showing an initial relative power and energization time when a light-emitting diode of the present invention and a light-emitting diode shown for comparison are energized at 60 mA.
[0053]
FIG. 3 is a graph showing a weather resistance test between a light emitting diode of the present invention and a light emitting diode shown for comparison.
[0054]
FIG. 4 is a schematic cross-sectional view of a light-emitting diode shown for comparison with the present invention.
[0055]
[Explanation of symbols]
101... Translucent resin used as mold resin
102... LED chip to be a light emitting element
103 ... Die bond resin
104 ... Wire
105 ... Mount lead
106 ... Inner lead
401... Translucent resin used as mold resin
402... LED chip to be a light emitting element
403 ... Die bond resin
404 ... wire
405 ... Mount lead
406 ... Inner lead

Claims (2)

少なくとも一対のリード電極と電気的に接続させた発光素子と、該発光素子を被覆する透光性樹脂とを有する発光ダイオードであって、
前記発光素子は、５５０ｎｍ以下の近紫外光から可視光に主発光ピークを発する発光層を有し、
前記透光性樹脂は、フェノール誘導体エポキシ樹脂が１０％未満のエポキシ樹脂組成物であり、
該エポキシ樹脂組成物は、エポキシ樹脂１００重量部に対し、
（ａ）炭素二重結合を化学的に有しない多塩基酸カルボン酸無水物を５０から１５０重量部
（ｂ）非芳香族かつ炭素二重結合を有しない炭素数２〜１２の直鎖型、分岐型、脂環型、エーテル基含有型のいずれかからなるアルコール・ポリオール類を１から３０重量部
（ｃ）ホスフィン類及び／又はそれらの第四級塩を０．０１〜１重量部、若しくは炭素二重結合を有しない有機カルボン酸金属塩を１から１０重量部
、含み、
経時劣化による黄変着色を低下させてなることを特徴とする発光ダイオード。A light emitting diode having at least a light emitting element electrically connected to a pair of lead electrodes, and a translucent resin covering the light emitting element;
The light emitting element has a light emitting layer that emits a main light emission peak from near ultraviolet light of 550 nm or less to visible light,
The translucent resin is an epoxy resin composition having a phenol derivative epoxy resin of less than 10%,
The epoxy resin composition is based on 100 parts by weight of the epoxy resin.
(A) 50 to 150 parts by weight of a polybasic acid carboxylic acid anhydride not chemically having a carbon double bond
(B) 1 to 30 parts by weight of an alcohol / polyol of any one of a linear type, a branched type, an alicyclic type, and an ether group-containing type having 2 to 12 carbon atoms that are non-aromatic and have no carbon double bond
(C) 0.01 to 1 part by weight of phosphines and / or quaternary salts thereof, or 1 to 10 parts by weight of an organic carboxylic acid metal salt having no carbon double bond ,
A light-emitting diode characterized by reducing yellowing coloring due to deterioration over time . 少なくとも一対のリード電極と電気的に接続させた発光素子と、該発光素子を被覆する透光性樹脂とを有する発光ダイオードであって、
前記発光素子は、発光層が５５０ｎｍ以下に主発光ピークを発する少なくともＩｎとＧａを含有する窒化物半導体であり、
前記透光性樹脂のエポキシ樹脂は、９０％以上が非芳香族のエポキシ樹脂組成物であり、
該エポキシ樹脂組成物は、エポキシ樹脂１００重量部に対し、
（ａ）炭素二重結合を化学的に有しない多塩基酸カルボン酸無水物を５０から１５０重量部
（ｂ）非芳香族かつ炭素二重結合を有しない炭素数２〜１２の直鎖型、分岐型、脂環型、エーテル基含有型のいずれかからなるアルコール・ポリオール類を１から３０重量部
（ｃ）ホスフィン類及び／又はそれらの第四級塩を０．０１〜１重量部、若しくは炭素二重結合を有しない有機カルボン酸金属塩を１から１０重量部
、含み、
経時劣化による黄変着色を低下させてなることを特徴とする発光ダイオード。A light emitting diode having at least a light emitting element electrically connected to a pair of lead electrodes, and a translucent resin covering the light emitting element;
The light-emitting element is a nitride semiconductor containing at least In and Ga whose light-emitting layer emits a main light emission peak at 550 nm or less,
90% or more of the epoxy resin of the translucent resin is a non-aromatic epoxy resin composition,
The epoxy resin composition is based on 100 parts by weight of the epoxy resin.
(A) 50 to 150 parts by weight of a polybasic acid carboxylic acid anhydride not chemically having a carbon double bond
(B) 1 to 30 parts by weight of an alcohol / polyol of any one of a linear type, a branched type, an alicyclic type, and an ether group-containing type having 2 to 12 carbon atoms that are non-aromatic and have no carbon double bond
(C) 0.01 to 1 part by weight of phosphines and / or quaternary salts thereof, or 1 to 10 parts by weight of an organic carboxylic acid metal salt having no carbon double bond ,
A light-emitting diode characterized by reducing yellowing coloring due to deterioration over time .
JP37135398A 1998-12-25 1998-12-25 Light emitting diode Expired - Fee Related JP3618238B2 (en)

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