JP2004259958A

JP2004259958A - Package for housing light emitting element, and light emitting device

Info

Publication number: JP2004259958A
Application number: JP2003049341A
Authority: JP
Inventors: Mitsuo Yanagisawa; 美津夫柳沢
Original assignee: Kyocera Corp
Current assignee: Kyocera Corp
Priority date: 2003-02-26
Filing date: 2003-02-26
Publication date: 2004-09-16

Abstract

<P>PROBLEM TO BE SOLVED: To provide a package for housing a light emitting element which allows light emitted from a light emitting element to be reflected well on the internal perimeter of a frame body and then to be efficiently and evenly emitted outside, and which can provide stable optical characteristics with no change in light intensity, emission angle of light, and light intensity profile due to a temperature change. <P>SOLUTION: The package for housing the light emitting element comprises a substrate 2 which has a mounting portion 2a to mount the light emitting element 5 at the center of an upper principal plane, and which is formed with a wiring conductor 3 derived outside from the mounting portion 2a; a metal frame body 4 which is installed in the periphery of the upper principal plane of the substrate 2 so as to surround the mounting portion 2a, and which has an internal face which is a tilted surface gradually expanded as it goes upwards; and a heat slinger 6 made of metal which is bonded to the center of a lower principal plane of the substrate 2. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、発光素子を収容するための発光素子収納用パッケージおよび発光装置に関する。
【０００２】
【従来の技術】
従来、発光ダイオード（ＬＥＤ）や半導体レーザ（ＬＤ）等の発光素子を用いた発光装置は、今後さらなる低消費電力化や長寿命化がすすむものと予測されていることから注目されており、近年各種インジケーター、光センサ、ディスプレイ、ホトカプラ、バックライト、光プリンタヘッド等の種々の分野で使用され始めている。従来の発光素子を搭載するための発光素子収納用パッケージ（以下、単にパッケージともいう）の断面図を図２に示す。
【０００３】
図２に示すように、従来のパッケージ１１は、一般に各種樹脂やセラミックスなどの材料から成る基体１２を有する。この基体１２には、タングステンやモリブデン−マンガン等を含む導体ペーストを塗布し焼成して成るメタライズ層を形成し、その上にメッキ法によりＮｉメッキ層やＡｕメッキ層を施した配線導体１３が形成されている。
【０００４】
また、配線導体１３は、発光素子１５を搭載する搭載部１２ａに、金（Ａｕ）や錫（Ｓｎ）−鉛（Ｐｎ）合金等から成る半田バンプ１７を介して発光素子１５を電気的に接続するための電極を有しており、配線導体１３と半田バンプ１７を介して、パッケージ１１内の発光素子１５に外部から駆動電流が供給される。
【０００５】
また基体１２は、パッケージ１１内部側の一方の主面に、中央部に上下面を貫通する貫通孔１４ａを有する、各種樹脂やセラミックスから成る枠体１４が設けられている。この枠体１４は、基体１２に７００〜９００℃の融点を有する銀（Ａｇ）−銅（Ｃｕ）等のロウ材や樹脂接着剤、５００℃以下で溶融する低融点ガラスなどにより固定される。
【０００６】
また、発光素子１５を保護するため、枠体１４の内側に発光素子１５を覆うように透明樹脂（図示せず）が設けられる。この透明樹脂は熱硬化性のエポキシ樹脂やシリコーン樹脂等を加熱硬化させることにより形成される。また、透明樹脂に発光素子１５の光を吸収し波長変換する少なくとも１つ以上の蛍光体を混入することにより、所望の色の光を取り出すことができる。さらに、透明樹脂は、発光素子１５をパッケージ１１に強固に密着させる働きも有する。これにより、発光素子１５を収納した発光装置となる。
【０００７】
この発光装置は、外部電気回路から供給される駆動電流によって発光素子１５が発光する。その用途としては、各種インジケーター、光センサ、ディスプレイ、ホトカプラ、バックライト、光プリンタヘッドなどがある。
【０００８】
近年、この発光装置を照明用として利用するようになってきており、高輝度、放熱性の点でより高特性のものが要求されている。また、照明用として使用する場合には寿命が重要な問題となるため、長寿命な発光装置が要求されている。
【０００９】
そこで、近時、発光装置の発光輝度を向上させるために、枠体１４や基体１２がより反射率の高い材料から成る構成とすることが多い。例えば、発光素子１５の光を反射させる枠体１４の材料にＡｇやＡｌからなる反射率の高い金属を使用したり、それらの金属を枠体１４の内周面に被着させることによって、高輝度の発光装置とすることが提案されている。
【００１０】
【特許文献１】
特開２００２−３４４０２９号公報
【００１１】
【発明が解決しようとする課題】
しかしながら、上記従来のパッケージ１１では、発光素子１５から出る熱によりパッケージ１１に歪みが発生し、その結果、発光素子１５から発光される光の放射角度が安定化しないという問題点があった。これは、基体１２が樹脂やセラミックスから成るのに対して枠体１４が金属から成るため、基体１２と枠体１４との熱膨張係数の違いにより発生するものである。
【００１２】
また、従来のパッケージ１１では、高輝度化には十分に対応できるものの、輝度を上げるために発光素子１５の入力パワーを上げると、発光素子１５から出る熱により安定した光強度、光の放射角度、光強度分布が得られないといった新たな問題がでてきている。また、放熱性が劣化すると、発光素子１５の温度が上昇し、発光素子１５の活性層から出射される光の取り出し効率、いわゆる内部量子効率が著しく劣化する。また、発光素子１５とパッケージ１１に歪みが生じ、パッケージ１１から一定の距離を置いたところで測定される光放射角度および光強度分布が所望の値およびパターンからずれることとなる。光強度分布は単一の光束（光ビーム）またはそれらの集合体で表されるものであり、パッケージ１１の歪みにより光束のパターンが一定にならず不安定となる。このように、発光装置が局部照明の用途等に使用される場合、光の放射角度、光強度分布は重要な問題である。
【００１３】
したがって、本発明はかかる従来の問題点に鑑みて完成されたものであり、その目的は、発光素子が発光する光を枠体の内周面で良好に反射させ外部に均一に効率よく放射させるとともに、温度変化によって光強度、光の放射角度および光強度分布が変化しない安定した光学的特性が得られる発光装置を作製できる発光素子収納用パッケージおよび発光装置を提供することにある。
【００１４】
【課題を解決するための手段】
本発明の発光素子パッケージは、上側主面の中央部に発光素子が搭載される搭載部を有するとともに該搭載部から外側にかけて導出される配線導体が形成された絶縁体から成る基体と、該基体の前記上側主面の外周部に前記搭載部を囲むように取着された、内周面が上方に向かって外側に広がる傾斜面とされた金属から成る枠体と、前記基体の下側主面の中央部に接合された金属から成る放熱板とを具備していることを特徴とする。
【００１５】
本発明の発光素子収納用パッケージは、上側主面の中央部に発光素子が搭載される搭載部を有するとともに搭載部から外側にかけて導出される配線導体が形成された絶縁体から成る基体と、基体の上側主面の外周部に搭載部を囲むように取着された、内周面が上方に向かって外側に広がる傾斜面とされた金属から成る枠体と、基体の下側主面の中央部に接合された金属から成る放熱板とを具備していることから、発光素子で発生する熱を配線導体で効率よく基体の内部に拡散させることができるとともに、基体の下側主面から放熱板に効率よく熱を伝達させることができる。従って、放熱板から外部回路基板に効率よく熱を放散でき、発光素子収納用パッケージ全体の温度上昇を有効に抑制できることから、基体と枠体との熱膨張差による歪みや変形を抑制できる。さらに、基体と枠体との接合界面で熱膨張係数差に起因し生じる熱応力を抑制できる。これらの結果、発光装置は安定した光放射角度および光強度分布でパッケージ外部に光を照射することができるとともに、互いに熱膨張係数の異なる、絶縁体から成る基体と金属から成る枠体との接合界面に生じるクラックや剥がれを抑制できる。従って、発光装置を長期にわたり正常に作動させることができる。
【００１６】
また、基体の上側主面に搭載部を囲むように取着された、内周面が上方に向かって外側に広がる傾斜面とされた金属から成る枠体を有していることから、枠体の内周面で発光素子の光を外部に８０％以上の反射率で反射させることができ、発光効率の高い発光装置を作製することができる。
【００１７】
本発明の発光装置は、本発明の発光素子収納用パッケージと、前記搭載部に搭載されるとともに前記配線導体に半田バンプを介して電気的に接続された発光素子と、前記枠体の内側またはその上方の前記発光素子の光軸上に設置された透光性部材とを具備していることを特徴とする。
【００１８】
本発明の発光装置は、上記の構成により、発光効率および放熱性に優れ、安定した光学的特性が得られる、高性能で信頼性の高いものとなる。
【００１９】
【発明の実施の形態】
本発明の発光素子収納用パッケージについて以下に詳細に説明する。図１は本発明のパッケージについて実施の形態の一例を示す断面図であり、図１において、２は基体、４は枠体、６は放熱板であり、これらで発光素子５を収容するためのパッケージ１が主に構成されている。
【００２０】
本発明のパッケージ１は、上側主面の中央部に発光素子５が搭載される搭載部２ａを有するとともに搭載部２ａから外側にかけて導出される配線導体３が形成された絶縁体から成る基体２と、基体２の上側主面の外周部に搭載部２ａを囲むように取着された、内周面が上方に向かって外側に広がる傾斜面とされた金属から成る枠体４と、基体２の下側主面の中央部に接合された金属から成る放熱板６とを具備している。
【００２１】
本発明における基体２は、例えば酸化アルミニウム質焼結体（アルミナセラミックス），窒化アルミニウム質焼結体，ムライト質焼結体，ガラスセラミックス等のセラミックスや、エポキシ樹脂等の樹脂から成る絶縁体であり、発光素子５を支持し搭載するための支持部材として機能するとともに、その上側主面の中央部には発光素子５を搭載する搭載部２ａが設けられている。
【００２２】
そして、基体２は、搭載部２ａの近傍からパッケージ外部に電気的な導通を行なう、タングステン（Ｗ），モリブデン（Ｍｏ），マンガン（Ｍｎ），銅（Ｃｕ）等のメタライズ層から成る配線導体３が形成されている。この配線導体３は、例えば、Ｗ等の粉末に有機溶剤、溶媒を添加混合して得た金属ペーストを、基体２となるセラミックグリーンシートに所定パターンに印刷塗布し、複数のセラミックグリーンシートを積層して焼成することによって形成される。配線導体３の表面には、酸化防止のためと発光素子５を低融点ロウ材等の半田バンプ７で強固に接続するために、厚さ０．５〜９μｍのＮｉ（ニッケル）層や厚さ０．５〜５μｍのＡｕ層等の金属層をメッキ法により被着させておくのが良い。
【００２３】
また、基板２の上側主面には、基板２の下側主面への光の透過を有効に抑制するとともに、基板２の上方に効率よく光を反射させるために、配線導体３に短絡しないようにしてＡｌ，Ａｇ，Ａｕ，Ｃｕ，Ｐｔ等の金属反射層を蒸着法や各種メッキ法により形成することが好ましい。
【００２４】
本発明の配線導体３は、ＡｕやＳｎ−Ｐｂ半田等の低融点ロウ材から成る半田バンプ７により発光素子５との電気的な接続が行なわれる電極パッドを有するとともに、発光素子５とパッケージ１外部との電気的な導通を行なう。そして、発光素子５が作動した際に、発光素子５の電極付近で発生する熱が半田バンプ７を介して配線導体３に伝熱するとともに、基体２の内層に形成された配線導体３を介して基体２全体に拡散される。その結果、基体２の内部を伝達する熱が十分に拡散されて、基体２の熱抵抗が低下するとともに基体２の下側主面の全体に熱が分布して効率よく放熱板６に伝達する。
【００２５】
本発明の放熱板６は、鉄（Ｆｅ）−ニッケル（Ｎｉ）−コバルト（Ｃｏ）合金やＣｕ−Ｗ合金等の金属から成り、そのインゴットに圧延加工や打ち抜き加工等の従来周知の金属加工を施すことによって所定形状に形成され製作される。とりわけ、放熱効果を高めるためには熱伝導性に優れたＣｕ−Ｗ合金からなることが好ましい。また、放熱板６は、その表面に耐食性に優れかつロウ材との濡れ性に優れる金属、具体的には厚さ０．５〜９μｍのＮｉ層と、厚さ０．５〜９μｍのＡｕ層とを順次メッキ法により被着させておくのがよく、放熱板６が酸化腐食されるのを有効に防止できる。
【００２６】
また、放熱板６は、その熱伝導率が１００Ｗ／ｍ・Ｋ以上であることがよい。これにより、発光素子５から放熱板６を介した外部回路基板への放熱性が向上し、発光素子５に入力できる駆動電流を大きくすることができる。
【００２７】
すなわち、１００Ｗ／ｍ・Ｋ以上では、駆動電流が２０ｍＡと大きい場合であっても発光素子５のジャンクション温度（所定の駆動電流を入力した際の発光素子５の最高温度で低い方がよい）が５０℃以下になり、１万時間を超えて正常かつ高輝度を確保して発光させることができるとともに、大きな駆動電流を入力することができ、発光素子５の輝度を向上させることができる。また、発光素子５が作動する際のパッケージ１全体の温度上昇が有効に抑制されて、基体２と枠体４との熱膨張差による変形や歪みが有効に抑制される。その結果、基体２および枠体４の中心軸と、発光素子５の光強度が最大となる光軸との位置ズレが抑制され、発光素子５の光が枠体４の内周面で反射し所望の放射角度と強度分布でパッケージ１外部へ効率よく出射されるとともに輝度が向上する。さらに、基体２と枠体４との接合界面で生じる、熱膨張係数差に起因する熱応力が低下し、基体２と枠体４との接合界面で生じるクラックや剥がれを有効に抑制できる。また、発光素子５の温度上昇が有効に抑制されることから、温度上昇に伴う発光素子５の活性層からの光の取り出し効率の低下が抑制され、発光装置は長期にわたり正常かつ安定に作動できる。
【００２８】
なお、チップジャンクション温度とは、所定の駆動電流（２０ｍＡ等）を入力した際のチップ（発光素子５）の温度であり、なるべく低い方がよい。すなわち、放熱性を高めないと発光素子５に熱がこもり、チップジャンクション温度が下がらないため、放熱性を高めてチップジャンクション温度を下げると、その分駆動電流が流せることになる。一般に、６５℃以上になれば発光素子５の限界を超えていると言われており、それ以上駆動電流を入力できなくなる。
【００２９】
放熱板６の熱伝導率が１００Ｗ／ｍ・Ｋ未満では、例えば駆動電流が２０ｍＡであると発光素子５のチップジャンクション温度が６５℃以上になり、発光素子５の発光効率が著しく劣化するとともに熱的負荷によって発光素子５を被覆するエポキシ樹脂やシリコーン樹脂等の透明樹脂の光透過率が劣化し、１万時間を超えて高輝度を確保して安定的に発光させるのが困難になる。
【００３０】
また、放熱板６は、枠体４との熱膨張係数差が５×１０^−６／℃以下であることがよい。これにより、パッケージ１の製造工程で銀ロウ等のロウ材を介して基体２と枠体４と放熱板６とを接合する際に、ロウ材が溶融する温度から常温に冷却され硬化する際に生じる、枠体４の収縮によって基体２に加わる曲げモーメントを放熱板６により緩和することができる。
【００３１】
また、枠体４は、Ａｌ，Ａｇ，Ｃｕ，Ａｕ，Ｐｔ，Ｆｅ−Ｎｉ−Ｃｏ合金，Ｆｅ−Ｎｉ合金等の金属からなり、とりわけ光の反射効果が高く低コストに製造できることからＡｌが好ましい。この枠体４は、上記の金属のインゴットに切削加工、圧延加工や打ち抜き加工等の従来周知の金属加工を施すことによって、内周面が上方に向かって外側に広がる貫通穴４ａが形成され、基体２の上側主面の外周部に搭載部２ａを囲むように取着される。
【００３２】
また、枠体４の貫通穴４ａは、その内周面が基体２の上側主面に対して３５〜６０度の角度で外側に広がるように形成されるのがよい。そして、貫通穴４ａに収容された発光素子５の光を傾斜した貫通穴４ａの内周面で反射させることにより、パッケージ１の外部へ光軸に対して２０度以内の範囲で良好に放射することができる。その結果、本発明のパッケージ１を使用した発光装置の輝度を極めて高いものとすることができる。
【００３３】
貫通穴４ａの内周面と基体２の上側主面とのなす角度が３５度未満になると、光の放射角度が２０度以上に分散し、指向性をもつ高出力の光を放射できない。また、６０度を超えると、発光素子５の光が効率よくパッケージ１の外部に放射されず、パッケージ１内を乱反射し損失が増加する。
【００３４】
なお、光の放射角度は、図１のような縦断面においてみた場合のものであり、光ビームの光軸に直交する断面における断面形状が円形状であれば放射角度は一定であり、光ビームの光軸に直交する断面における断面形状が楕円形状等の偏りがある場合は放射角度はその最大値とする。
【００３５】
また、枠体４の貫通穴４ａの内周面の算術平均粗さＲａは０．００４〜４μｍが好ましい。４μｍを超えると、貫通穴４ａに収容された発光素子５の光を均一に反射することが困難になり、反射する光の強さに偏りが発生しやすくなる。０．００４μｍ未満であると、そのような平滑な面を安定かつ効率よく形成することが困難となる傾向にある。貫通穴４ａの内周面のＲａを上記の範囲とするには、従来周知の化学エッチング法や切削加工方法により加工することができる。また、金型の面精度を利用した転写加工による方法を用いてもよい。
【００３６】
また、枠体４の上側主面と内周面との間に段差４ｂを形成し、その段差４ｂに、集光レンズ等の機能を有するガラス，サファイア，プラスチック，石英等から成る透光性部材８の端部を係止し接着等して設置することがよい。この場合、発光素子５と透光性部材８との光学的な結合状態を安定に維持することができ、光学的特性が安定化した発光装置となすことができる。
【００３７】
本発明においては、基体２と枠体４との接合は、シリコーン樹脂系やエポキシ樹脂系等の樹脂接着剤、Ａｇ−Ｃｕロウ等のロウ材、またはＰｂ−Ｓｎ合金，Ａｕ−Ｓｎ合金，Ａｕ−Ｓｉ合金等の半田などの接合材により行なわれる。この接合材は、基体２および枠体４の材質や熱膨張係数等を考慮して適宜選定すればよく、特に限定されるものではないが、接合の高信頼性を必要とされる場合にはロウ材や半田が好ましい。
【００３８】
また本発明において、熱膨張係数が約７×１０^−６〜８×１０^−６／℃であるアルミナセラミックス等から成る基体２と、その上側主面の外周部に接合された熱膨張係数が約２３×１０^−６／℃であるアルミニウム等から成る枠体４と、基体２の下側主面の中央部に接合された熱膨張係数が約６×１０^−６〜１０×１０^−６／℃であるＦｅ−Ｎｉ−Ｃｏ合金等から成る放熱板６との間の熱膨張差によって、基体２にクラック等が発生するのを抑制するうえで、放熱板６の外周端が枠体４の下面の内周端の直下よりも基板２の下側主面の外周側にあることが好ましい。これにより、基体２が、それと同程度の熱膨張係数を有する放熱板６によって補強され、基体２にクラック等が発生するのを効果的に抑えられる。さらには、放熱板６の外周端が枠体４の下面の中央部よりも基板２の下側主面の外周側にあることがより好ましい。これにより、基体２の補強効果がより高まり、基体２にクラック等が発生するのをさらに効果的に抑えられる。
【００３９】
なお、基体２の下側主面の外周部には配線導体３が露出しているため、放熱板６の外周端は基板２の下側主面の外周端に達していないのがよい。
【００４０】
かくして、本発明のパッケージは、基体２の搭載部２ａに発光素子５を搭載し、発光素子５の電極と配線導体３とを半田バンプ７を介して電気的に接続し、しかる後、発光素子５をシリコーン樹脂等の透明樹脂で覆うか、または発光素子５が収容された貫通穴４ａ内に透明樹脂を充填して発光素子５を封止し、枠体４の上方の発光素子５の光軸上に設置されるとともに枠体４の上側主面の段差４ｂに透光性部材８を設置することで発光装置となる。
【００４１】
なお、本発明は上記の実施の形態に限定されず、本発明の要旨を逸脱しない範囲内で種々の変更を行うことは何等支障ない。
【００４２】
【発明の効果】
本発明の発光素子収納用パッケージは、上側主面の中央部に発光素子が搭載される搭載部を有するとともに搭載部から外側にかけて導出される配線導体が形成された絶縁体から成る基体と、基体の上側主面の外周部に搭載部を囲むように取着された、内周面が上方に向かって外側に広がる傾斜面とされた金属から成る枠体と、基体の下側主面の中央部に接合された金属から成る放熱板とを具備していることから、発光素子で発生する熱を配線導体で効率よく基体の内部に拡散させることができるとともに、基体の下側主面から放熱板に効率よく熱を伝達させることができる。従って、放熱板から外部回路基板に効率よく熱を放散でき、発光素子収納用パッケージ全体の温度上昇を有効に抑制できることから、基体と枠体との熱膨張差による歪みや変形を抑制できる。さらに、基体と枠体との接合界面で熱膨張係数差に起因し生じる熱応力を抑制できる。その結果、発光装置は安定した光放射角度および光強度分布でパッケージ外部に光を放射できるとともに、互いに熱膨張係数の異なる基体と枠体との接合界面に生じるクラックや剥がれを抑制できる。従って、発光装置を長期にわたり正常に作動させることができる。
【００４３】
また、基体の上側主面に搭載部を囲むように取着された、内周面が上方に向かって外側に広がる傾斜面とされた金属から成る枠体を有していることから、枠体の内周面で発光素子の光を外部に８０％以上の反射率で反射させることができ、発光効率の高い発光装置を作製することができる。
【００４４】
本発明の発光装置は、本発明の発光素子収納用パッケージと、搭載部に搭載されるとともに配線導体に半田バンプを介して電気的に接続された発光素子と、枠体の内側またはその上方の発光素子の光軸上に設置された透光性部材とを具備していることにより、発光効率および放熱性に優れ、安定した光学的特性が得られる、高性能で信頼性の高いものとなる。
【図面の簡単な説明】
【図１】本発明の発光素子収納用パッケージについて実施の形態の一例を示す断面図である。
【図２】従来の発光素子収納用パッケージの断面図である。
【符号の説明】
１：発光素子収納用パッケージ
２：基体
２ａ：搭載部
３：配線導体
４：枠体
５：発光素子
６：放熱板
８：透光性部材[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a light emitting element housing package for housing a light emitting element and a light emitting device.
[0002]
[Prior art]
Conventionally, light-emitting devices using light-emitting elements such as light-emitting diodes (LEDs) and semiconductor lasers (LDs) have attracted attention because they are expected to have lower power consumption and longer life in the future. It has begun to be used in various fields such as various indicators, optical sensors, displays, photocouplers, backlights, and optical printer heads. FIG. 2 is a cross-sectional view of a light emitting element housing package (hereinafter, also simply referred to as a package) for mounting a conventional light emitting element.
[0003]
As shown in FIG. 2, a conventional package 11 generally has a base 12 made of a material such as various resins and ceramics. A metallized layer formed by applying and firing a conductive paste containing tungsten, molybdenum-manganese, or the like is formed on the base 12, and a wiring conductor 13 having a Ni plating layer or an Au plating layer formed thereon by plating is formed. Have been.
[0004]
The wiring conductor 13 electrically connects the light emitting element 15 to the mounting portion 12a on which the light emitting element 15 is mounted via a solder bump 17 made of gold (Au), tin (Sn) -lead (Pn) alloy, or the like. The drive current is supplied from the outside to the light emitting element 15 in the package 11 via the wiring conductor 13 and the solder bump 17.
[0005]
The base 12 is provided with a frame 14 made of various resins and ceramics and having a through hole 14a penetrating the upper and lower surfaces at the center on one main surface on the inner side of the package 11. The frame 14 is fixed to the base 12 with a brazing material such as silver (Ag) -copper (Cu) having a melting point of 700 to 900 ° C., a resin adhesive, a low-melting glass melting at 500 ° C. or lower.
[0006]
In order to protect the light emitting element 15, a transparent resin (not shown) is provided inside the frame 14 so as to cover the light emitting element 15. This transparent resin is formed by heat-curing a thermosetting epoxy resin or silicone resin. In addition, by mixing at least one or more phosphors that absorb light from the light emitting element 15 and convert the wavelength into the transparent resin, light of a desired color can be extracted. Further, the transparent resin has a function of firmly attaching the light emitting element 15 to the package 11. Thus, a light emitting device containing the light emitting element 15 is obtained.
[0007]
In this light emitting device, the light emitting element 15 emits light by a driving current supplied from an external electric circuit. Its applications include various indicators, optical sensors, displays, photocouplers, backlights, optical printer heads, and the like.
[0008]
In recent years, this light-emitting device has been used for lighting, and a device having higher characteristics in terms of high luminance and heat dissipation is required. In addition, when used for lighting, the life is an important issue, and a long-life light emitting device is required.
[0009]
Therefore, recently, in order to improve the light emission luminance of the light emitting device, the frame 14 and the base 12 are often made of a material having a higher reflectance. For example, a high-reflectance metal such as Ag or Al is used as the material of the frame 14 that reflects the light of the light-emitting element 15, or the metal is adhered to the inner peripheral surface of the frame 14, thereby increasing the height. It has been proposed to use a light emitting device having a high luminance.
[0010]
[Patent Document 1]
JP 2002-344029 A
[Problems to be solved by the invention]
However, the conventional package 11 has a problem in that heat generated from the light emitting element 15 causes distortion in the package 11, and as a result, the emission angle of light emitted from the light emitting element 15 is not stabilized. This is caused by the difference in the coefficient of thermal expansion between the base 12 and the frame 14 because the frame 12 is made of metal while the base 12 is made of resin or ceramics.
[0012]
Although the conventional package 11 can sufficiently cope with high luminance, if the input power of the light emitting element 15 is increased in order to increase the luminance, the light emitted from the light emitting element 15 has a stable light intensity and light emission angle. And a new problem that a light intensity distribution cannot be obtained. Further, when the heat radiation property deteriorates, the temperature of the light emitting element 15 rises, and the light extraction efficiency of light emitted from the active layer of the light emitting element 15, that is, the so-called internal quantum efficiency deteriorates remarkably. Also, distortion occurs between the light emitting element 15 and the package 11, and the light emission angle and light intensity distribution measured at a certain distance from the package 11 deviate from desired values and patterns. The light intensity distribution is represented by a single light beam (light beam) or an aggregate thereof, and the pattern of the light beam becomes unstable due to distortion of the package 11 and becomes unstable. As described above, when the light emitting device is used for local illumination, the light emission angle and light intensity distribution are important issues.
[0013]
Therefore, the present invention has been completed in view of such a conventional problem, and an object of the present invention is to efficiently reflect light emitted from a light emitting element on an inner peripheral surface of a frame body and radiate the light uniformly and efficiently to the outside. Another object of the present invention is to provide a light-emitting element housing package and a light-emitting device capable of manufacturing a light-emitting device capable of obtaining stable optical characteristics in which light intensity, light emission angle, and light intensity distribution do not change due to temperature change.
[0014]
[Means for Solving the Problems]
A light-emitting element package according to the present invention includes a base made of an insulator having a mounting portion on which a light-emitting element is mounted in a center portion of an upper main surface and having a wiring conductor led out from the mounting portion to the outside; A metal frame attached to the outer peripheral portion of the upper main surface so as to surround the mounting portion, the inner peripheral surface being a sloping surface extending outwardly toward the upper side; And a radiator plate made of metal joined to the center of the surface.
[0015]
A light-emitting element housing package according to the present invention includes a base made of an insulator having a mounting portion in which a light-emitting element is mounted in a central portion of an upper main surface and having a wiring conductor led out from the mounting portion to the outside; A metal frame attached to the outer peripheral portion of the upper main surface of the upper surface so as to surround the mounting portion, the inner peripheral surface of the metal body being an inclined surface extending outward outward, and the center of the lower main surface of the base And a heat radiating plate made of metal bonded to the portion, the heat generated by the light emitting element can be efficiently diffused into the base by the wiring conductor, and the heat is radiated from the lower main surface of the base. Heat can be efficiently transmitted to the plate. Therefore, heat can be efficiently dissipated from the heat radiating plate to the external circuit board, and the temperature rise of the entire light emitting element housing package can be effectively suppressed, so that distortion and deformation due to a difference in thermal expansion between the base and the frame can be suppressed. Further, thermal stress caused by a difference in thermal expansion coefficient at the joint interface between the base and the frame can be suppressed. As a result, the light emitting device can irradiate light to the outside of the package with a stable light emission angle and light intensity distribution, and also joins a base made of an insulator and a frame made of a metal having different thermal expansion coefficients to each other. Cracks and peeling occurring at the interface can be suppressed. Therefore, the light emitting device can be normally operated for a long time.
[0016]
In addition, the frame body is attached to the upper main surface of the base body so as to surround the mounting portion, and the frame body is made of a metal whose inner peripheral surface is an inclined surface extending outwardly upward. The light from the light emitting element can be reflected to the outside at a reflectance of 80% or more on the inner peripheral surface of the light emitting element, and a light emitting device with high luminous efficiency can be manufactured.
[0017]
The light-emitting device of the present invention is a light-emitting element housing package of the present invention, a light-emitting element mounted on the mounting portion and electrically connected to the wiring conductor via a solder bump, or inside the frame or A light-transmitting member provided on the optical axis of the light-emitting element above the light-emitting element.
[0018]
The light-emitting device of the present invention has high performance and high reliability with excellent luminous efficiency and heat dissipation, stable optical characteristics, and high luminous efficiency.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
The light emitting element housing package of the present invention will be described in detail below. FIG. 1 is a cross-sectional view showing an example of an embodiment of the package of the present invention. In FIG. 1, reference numeral 2 denotes a base, 4 is a frame, and 6 is a heat radiating plate. The package 1 is mainly configured.
[0020]
The package 1 of the present invention includes a base 2 made of an insulator having a mounting portion 2a on which a light emitting element 5 is mounted at a central portion of an upper main surface, and a wiring conductor 3 extending from the mounting portion 2a to the outside. A frame 4 made of a metal whose inner peripheral surface is an inclined surface extending outwardly upward and attached to the outer peripheral portion of the upper main surface of the base 2 so as to surround the mounting portion 2a; A heat radiating plate 6 made of metal joined to a central portion of the lower main surface.
[0021]
The base 2 in the present invention is an insulator made of a ceramic such as an aluminum oxide sintered body (alumina ceramic), an aluminum nitride sintered body, a mullite sintered body, a glass ceramic, or a resin such as an epoxy resin. The light-emitting element 5 functions as a support member for supporting the light-emitting element 5, and a mounting portion 2 a for mounting the light-emitting element 5 is provided at the center of the upper main surface.
[0022]
The base 2 is a wiring conductor 3 made of a metallized layer of tungsten (W), molybdenum (Mo), manganese (Mn), copper (Cu), etc., which conducts electrical conduction from the vicinity of the mounting portion 2a to the outside of the package. Is formed. The wiring conductor 3 is formed by, for example, applying a metal paste obtained by adding and mixing an organic solvent and a solvent to a powder of W or the like on a ceramic green sheet serving as the base 2 in a predetermined pattern, and laminating a plurality of ceramic green sheets. And fired. On the surface of the wiring conductor 3, a Ni (nickel) layer having a thickness of 0.5 to 9 μm or a thickness of 0.5 to 9 μm is provided on the surface of the wiring conductor 3 in order to prevent oxidation and to firmly connect the light emitting element 5 with a solder bump 7 such as a low melting point brazing material. A metal layer such as an Au layer having a thickness of 0.5 to 5 μm is preferably applied by plating.
[0023]
In addition, the upper main surface of the substrate 2 is not short-circuited to the wiring conductor 3 in order to effectively suppress light transmission to the lower main surface of the substrate 2 and reflect light efficiently above the substrate 2. In this manner, it is preferable to form the metal reflection layer of Al, Ag, Au, Cu, Pt, or the like by a vapor deposition method or various plating methods.
[0024]
The wiring conductor 3 of the present invention has an electrode pad that is electrically connected to the light emitting element 5 by a solder bump 7 made of a low melting point brazing material such as Au or Sn—Pb solder. Conducts electrical communication with the outside. Then, when the light emitting element 5 is operated, heat generated near the electrodes of the light emitting element 5 is transferred to the wiring conductor 3 via the solder bumps 7 and is also transmitted through the wiring conductor 3 formed on the inner layer of the base 2. And diffused throughout the substrate 2. As a result, the heat transmitted inside the base 2 is sufficiently diffused, the thermal resistance of the base 2 is reduced, and the heat is distributed to the entire lower main surface of the base 2 and is efficiently transferred to the heat radiating plate 6. .
[0025]
The heat radiating plate 6 of the present invention is made of a metal such as an iron (Fe) -nickel (Ni) -cobalt (Co) alloy or a Cu-W alloy, and the ingot is subjected to conventionally known metal working such as rolling or punching. By applying, it is formed and manufactured in a predetermined shape. In particular, in order to enhance the heat radiation effect, it is preferable to use a Cu-W alloy having excellent thermal conductivity. Further, the heat radiating plate 6 has, on its surface, a metal having excellent corrosion resistance and excellent wettability with a brazing material, specifically, a Ni layer having a thickness of 0.5 to 9 μm and an Au layer having a thickness of 0.5 to 9 μm. It is preferable that the heat radiation plate 6 is effectively prevented from being oxidized and corroded.
[0026]
Further, the heat radiation plate 6 preferably has a thermal conductivity of 100 W / m · K or more. Thereby, the heat radiation from the light emitting element 5 to the external circuit board via the heat radiating plate 6 is improved, and the driving current that can be input to the light emitting element 5 can be increased.
[0027]
That is, at 100 W / m · K or more, the junction temperature of the light emitting element 5 (the lower the highest temperature of the light emitting element 5 when a predetermined driving current is input is better) even if the driving current is as large as 20 mA. The temperature can be reduced to 50 ° C. or less, and light can be emitted while maintaining normal and high brightness for more than 10,000 hours, a large driving current can be input, and the brightness of the light emitting element 5 can be improved. In addition, the temperature rise of the entire package 1 when the light emitting element 5 operates is effectively suppressed, and deformation and distortion due to a difference in thermal expansion between the base 2 and the frame 4 are effectively suppressed. As a result, the positional deviation between the central axis of the base 2 and the frame 4 and the optical axis at which the light intensity of the light emitting element 5 becomes maximum is suppressed, and the light of the light emitting element 5 is reflected on the inner peripheral surface of the frame 4. The light is efficiently emitted to the outside of the package 1 at a desired radiation angle and intensity distribution, and the luminance is improved. Furthermore, the thermal stress caused at the joint interface between the base 2 and the frame 4 due to the difference in thermal expansion coefficient is reduced, and cracks and peeling at the joint interface between the base 2 and the frame 4 can be effectively suppressed. Further, since the temperature rise of the light emitting element 5 is effectively suppressed, a decrease in the light extraction efficiency from the active layer of the light emitting element 5 due to the temperature rise is suppressed, and the light emitting device can operate normally and stably for a long time. .
[0028]
Note that the chip junction temperature is the temperature of the chip (the light emitting element 5) when a predetermined drive current (20 mA or the like) is input, and the lower the better, the better. That is, if the heat dissipation is not enhanced, heat is accumulated in the light emitting element 5 and the chip junction temperature does not decrease. Therefore, if the heat dissipation is increased and the chip junction temperature is decreased, the drive current can flow accordingly. It is generally said that when the temperature exceeds 65 ° C., the limit of the light emitting element 5 is exceeded, and the drive current cannot be input any more.
[0029]
When the heat conductivity of the heat sink 6 is less than 100 W / m · K, for example, when the driving current is 20 mA, the chip junction temperature of the light emitting element 5 becomes 65 ° C. or more, so that the light emitting efficiency of the light emitting element 5 is significantly deteriorated, and The light load deteriorates the light transmittance of a transparent resin such as an epoxy resin or a silicone resin which covers the light emitting element 5 due to a mechanical load, and it is difficult to secure high luminance for more than 10,000 hours and stably emit light.
[0030]
Further, the heat radiating plate 6 preferably has a thermal expansion coefficient difference from the frame 4 of 5 × 10 ⁻⁶ / ° C. or less. Accordingly, when the base 2, the frame 4, and the heat radiating plate 6 are joined via the brazing material such as silver brazing in the manufacturing process of the package 1, when the brazing material is cooled from room temperature to room temperature and hardened. The bending moment applied to the base 2 due to the contraction of the frame body 4 can be reduced by the heat sink 6.
[0031]
The frame 4 is made of a metal such as Al, Ag, Cu, Au, Pt, an Fe—Ni—Co alloy, and an Fe—Ni alloy. Al is preferable because it has a high light reflection effect and can be manufactured at low cost. . This frame 4 is provided with a through-hole 4a whose inner peripheral surface is outwardly expanded upward by performing conventionally known metal processing such as cutting, rolling, and punching on the metal ingot. The mounting portion 2a is attached to the outer peripheral portion of the upper main surface of the base 2 so as to surround the mounting portion 2a.
[0032]
The through hole 4a of the frame 4 is preferably formed such that its inner peripheral surface extends outward at an angle of 35 to 60 degrees with respect to the upper main surface of the base 2. Then, by reflecting the light of the light emitting element 5 housed in the through hole 4a on the inner peripheral surface of the inclined through hole 4a, the light is radiated well to the outside of the package 1 within a range of 20 degrees with respect to the optical axis. be able to. As a result, the luminance of the light emitting device using the package 1 of the present invention can be extremely high.
[0033]
When the angle between the inner peripheral surface of the through hole 4a and the upper main surface of the base 2 is less than 35 degrees, the light emission angle is dispersed to 20 degrees or more, and high-output light having directivity cannot be emitted. When the angle exceeds 60 degrees, the light of the light emitting element 5 is not efficiently emitted to the outside of the package 1 and is irregularly reflected in the package 1 to increase the loss.
[0034]
Note that the light emission angle is that observed in a vertical section as shown in FIG. 1. If the cross-sectional shape in a cross section orthogonal to the optical axis of the light beam is circular, the emission angle is constant. In the case where the cross-sectional shape in the cross section orthogonal to the optical axis has a deviation such as an elliptical shape, the radiation angle is set to the maximum value.
[0035]
The arithmetic average roughness Ra of the inner peripheral surface of the through hole 4a of the frame 4 is preferably 0.004 to 4 μm. If the thickness exceeds 4 μm, it is difficult to uniformly reflect the light of the light emitting element 5 housed in the through hole 4a, and the intensity of the reflected light tends to be uneven. If it is less than 0.004 μm, it tends to be difficult to form such a smooth surface stably and efficiently. In order to set Ra of the inner peripheral surface of the through hole 4a to the above range, the Ra can be processed by a conventionally known chemical etching method or cutting method. Alternatively, a method based on transfer processing utilizing the surface accuracy of a mold may be used.
[0036]
In addition, a step 4b is formed between the upper main surface and the inner peripheral surface of the frame 4, and a translucent member made of glass, sapphire, plastic, quartz, or the like having a function as a condensing lens or the like is formed on the step 4b. It is preferable to lock the end of 8 and install it by bonding or the like. In this case, the optical coupling state between the light emitting element 5 and the translucent member 8 can be stably maintained, and a light emitting device with stabilized optical characteristics can be provided.
[0037]
In the present invention, the bonding between the base 2 and the frame 4 is performed by a resin adhesive such as a silicone resin or an epoxy resin, a brazing material such as Ag-Cu brazing, a Pb-Sn alloy, an Au-Sn alloy, or Au. -It is performed by a bonding material such as solder such as a Si alloy. This joining material may be appropriately selected in consideration of the materials of the base 2 and the frame 4 and the thermal expansion coefficient, and is not particularly limited. However, when high reliability of joining is required, A brazing material or solder is preferred.
[0038]
In the present invention, the base 2 made of alumina ceramics having a thermal expansion coefficient of about 7 × 10 ⁻⁶ to 8 × 10 ⁻⁶ / ° C. and a thermal expansion coefficient of about 2 × 10 ⁻⁶ / ° C. A frame 4 made of aluminum or the like having a temperature of 23 × 10 ⁻⁶ / ° C., and a thermal expansion coefficient of about 6 × 10 ⁻⁶ to 10 × 10 ⁻⁶ / ° C. joined to the center of the lower main surface of the base 2 In order to suppress the occurrence of cracks and the like in the base 2 due to the difference in thermal expansion between the heat radiating plate 6 and the heat radiating plate 6 made of an Fe—Ni—Co alloy or the like, the outer peripheral end of the heat radiating plate 6 Is preferably on the outer peripheral side of the lower main surface of the substrate 2 rather than immediately below the inner peripheral end of the substrate 2. Thereby, the base 2 is reinforced by the heat radiating plate 6 having the same thermal expansion coefficient as that of the base 2, and cracks and the like in the base 2 can be effectively suppressed. Further, it is more preferable that the outer peripheral edge of the heat radiating plate 6 is located closer to the outer peripheral side of the lower main surface of the substrate 2 than the center of the lower surface of the frame 4. Thereby, the effect of reinforcing the base 2 is further enhanced, and the occurrence of cracks and the like in the base 2 can be more effectively suppressed.
[0039]
Since the wiring conductor 3 is exposed at the outer peripheral portion of the lower main surface of the base 2, the outer peripheral edge of the heat sink 6 may not reach the outer peripheral edge of the lower main surface of the substrate 2.
[0040]
Thus, in the package of the present invention, the light emitting element 5 is mounted on the mounting portion 2 a of the base 2, and the electrode of the light emitting element 5 and the wiring conductor 3 are electrically connected via the solder bump 7. 5 is covered with a transparent resin such as a silicone resin, or a transparent resin is filled in the through hole 4a in which the light emitting element 5 is accommodated, and the light emitting element 5 is sealed. A light-emitting device is provided by being installed on the shaft and by installing the translucent member 8 on the step 4 b on the upper main surface of the frame 4.
[0041]
It should be noted that the present invention is not limited to the above embodiment, and that various changes may be made without departing from the scope of the present invention.
[0042]
【The invention's effect】
A light-emitting element housing package according to the present invention includes a base made of an insulator having a mounting portion in which a light-emitting element is mounted in a central portion of an upper main surface and having a wiring conductor led out from the mounting portion to the outside; A metal frame attached to the outer peripheral portion of the upper main surface of the upper surface so as to surround the mounting portion, the inner peripheral surface of the metal body being an inclined surface extending outward outward, and the center of the lower main surface of the base And a heat radiating plate made of metal bonded to the portion, the heat generated by the light emitting element can be efficiently diffused into the base by the wiring conductor, and the heat is radiated from the lower main surface of the base. Heat can be efficiently transmitted to the plate. Therefore, heat can be efficiently dissipated from the heat radiating plate to the external circuit board, and the temperature rise of the entire light emitting element housing package can be effectively suppressed, so that distortion and deformation due to a difference in thermal expansion between the base and the frame can be suppressed. Further, thermal stress caused by a difference in thermal expansion coefficient at the joint interface between the base and the frame can be suppressed. As a result, the light emitting device can emit light to the outside of the package with a stable light emission angle and light intensity distribution, and can also suppress cracks and peeling occurring at the joint interface between the base and the frame having different thermal expansion coefficients. Therefore, the light emitting device can be normally operated for a long time.
[0043]
In addition, the frame body is attached to the upper main surface of the base body so as to surround the mounting portion, and the frame body is made of a metal whose inner peripheral surface is an inclined surface extending outwardly upward. The light from the light emitting element can be reflected to the outside with a reflectance of 80% or more on the inner peripheral surface of the light emitting element, and a light emitting device with high luminous efficiency can be manufactured.
[0044]
The light emitting device of the present invention includes a light emitting element housing package of the present invention, a light emitting element mounted on a mounting portion and electrically connected to a wiring conductor via a solder bump, and a light emitting element inside or above the frame. By providing a light-transmitting member provided on the optical axis of the light-emitting element, the light-emitting element has excellent luminous efficiency and heat dissipation, and can obtain stable optical characteristics, and has high performance and high reliability. .
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating an example of an embodiment of a light emitting element housing package of the present invention.
FIG. 2 is a cross-sectional view of a conventional light emitting element storage package.
[Explanation of symbols]
1: Package for housing light emitting element 2: Base 2a: Mounting portion 3: Wiring conductor 4: Frame 5: Light emitting element 6: Heat sink 8: Translucent member

Claims

A base made of an insulator having a mounting portion on which the light emitting element is mounted at the center of the upper main surface and having a wiring conductor led out from the mounting portion to the outside, and an outer peripheral portion of the upper main surface of the base A frame body made of a metal attached to the mounting portion so as to surround the mounting portion and having an inclined inner surface extending outwardly upward, and joined to a central portion of a lower main surface of the base. A light-emitting element storage package, comprising: a heat sink made of metal.

2. The light-emitting element storage package according to claim 1, the light-emitting element mounted on the mounting portion and electrically connected to the wiring conductor via a solder bump, and the light emission inside or above the frame. A light-transmitting member provided on the optical axis of the element.