JP3787220B2 - Chip light emitting device - Google Patents

Chip light emitting device Download PDF

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JP3787220B2
JP3787220B2 JP20468597A JP20468597A JP3787220B2 JP 3787220 B2 JP3787220 B2 JP 3787220B2 JP 20468597 A JP20468597 A JP 20468597A JP 20468597 A JP20468597 A JP 20468597A JP 3787220 B2 JP3787220 B2 JP 3787220B2
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chip
light emitting
voltage
emitting element
led chip
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JPH1154801A (en
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慎二 磯川
秀和 戸田
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Rohm Co Ltd
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Rohm Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/483—Containers
    • H01L33/486—Containers adapted for surface mounting
    • 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
    • H01L2224/481—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
    • H01L2224/48225—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 non-metallic, e.g. insulating substrate with or without metallisation
    • H01L2224/48227—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 non-metallic, e.g. insulating substrate with or without metallisation 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
    • H01L2224/01—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
    • H01L2224/484—Connecting portions
    • H01L2224/48463—Connecting portions the connecting portion on the bonding area of the semiconductor or solid-state body being a ball bond
    • H01L2224/48465—Connecting portions the connecting portion on the bonding area of the semiconductor or solid-state body being a ball bond the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/10—Details of semiconductor or other solid state devices to be connected
    • H01L2924/11—Device type
    • H01L2924/13—Discrete devices, e.g. 3 terminal devices
    • H01L2924/1304—Transistor
    • H01L2924/1306—Field-effect transistor [FET]
    • H01L2924/13091—Metal-Oxide-Semiconductor Field-Effect Transistor [MOSFET]

Description

【０００１】
【発明の属する技術分野】
本発明は携帯電話機やＰＨＳなどの携帯用電子機器の照明や表示用などの光源に用いられるのに適した小型で、基板からの高さが非常に低い薄型のチップ型発光素子に関する。さらに詳しくは、交流電圧駆動または静電気などにより発光素子に逆方向電圧や所定の電圧以上の順方向電圧が印加される場合にも発光素子がその静電気などにより破壊しにくいように保護素子が設けられているチップ型発光素子に関する。
【０００２】
【従来の技術】
携帯電話機やＰＨＳなどの携帯機器の小形化に伴い、それらに用いられる発光素子なども軽薄短小化が要求され、とくに高さが低い薄型のチップ型発光素子が要求されている。
【０００３】
この種の小形で薄型のチップ型発光素子は図５（ａ）に示されるように、基板１０の両端部に端子電極１、２が形成され、一方の端子電極１と接続され端子電極の一部となる電極上に発光ダイオード（以下、ＬＥＤという）チップ３がボンディングされてその下部電極が端子電極１と直接接続され、その上部電極が金線４により他方の端子電極２とワイヤボンディングされて、それぞれ電気的に接続されている。ＬＥＤチップ３は、たとえば図５（ｂ）に示されるように、ＧａＡｓやＧａＰなどからなるｎ型半導体層４１とｐ型半導体層４２との接合によるｐｎ接合面（発光層）４３が形成され、その両面に電極４４、４５が設けられることにより構成されている。この基板１０の表面側には、透明または乳白色のエポキシ樹脂などからなる樹脂によりＬＥＤチップ３や金線４を被覆して保護するパッケージ６が形成されている。
【０００４】
このような発光素子は、ダイオード構造になっているため、逆方向の電圧が印加されても電流が流れない整流作用を利用して、直流電圧を両電極間に印加しないで交流電圧を印加することにより、交流で順方向電圧になる場合にのみ電流が流れて発光する光を利用する使用方法も採用されている。
【０００５】
【発明が解決しようとする課題】
従来のチップ型発光素子は、ＬＥＤチップの厚さが０.３ｍｍ程度はあり、しかもワイヤボンディングがなされているため、基板からの高さを０.６ｍｍ程度より薄くすることは難しく、最終製品としては０.８〜１ｍｍ程度となってしまう。一方において、発光素子として用いられるＧａＡｓ系やＧａＰ系やチッ化ガリウム系などの化合物半導体では、逆方向に印加される電圧や高電圧に対して弱く、半導体層が破壊することがある。とくに、チッ化ガリウム系化合物半導体においては、その逆方向の耐圧が５０Ｖ程度と低く逆方向の印加電圧に対してとくに破壊しやすいこと、またバンドギャップエネルギーが大きいため、ＧａＡｓ系などを用いた発光素子より動作電圧も高くなること、などのため交流電圧の印加で半導体発光素子が破損したり、その特性が劣化するという問題がある。
【０００６】
また、交流電圧を印加する駆動でなくても、外部からサージ電圧などの大きな電圧が印加される場合、チッ化ガリウム系化合物半導体では順方向電圧でも１５０Ｖ程度で破壊されやすいという問題がある。
【０００７】
これらの逆方向電圧や静電気の印加に対する破壊を防止するため、半導体発光素子が組み込まれる回路内で、半導体発光素子と並列で半導体発光素子と逆方向にツェナーダイオードを組み込むことが行われる場合もある。しかし、回路内に組み込まれる前の製造工程や出荷に伴う搬送工程、または回路基板に組み込む際などのハンドリング時に静電気で破壊したり、外部回路でＬＥＤの他にダイオードなどを組み込むスペースや工数を必要とするという問題がある。
【０００８】
本発明はこのような問題を解決するためになされたもので、小形で非常に薄型でありながら、逆方向電圧や静電気などのサージ電圧の印加に対して強く、取扱が容易なチップ型発光素子を提供することを目的とする。
【０００９】
【課題を解決するための手段】
本発明によるチップ型発光素子は、絶縁性基板と、該絶縁性基板の表面の両端部にそれらの一端部が一定間隙を有して対向するように設けられる第１および第２の端子電極と、前記第１および第２の端子電極にそれぞれ第１および第２の電極が導電性接着剤により直接接続される発光素子チップと、前記第１および第２の端子電極間に２つの電極がそれぞれ導電性接着剤により直接接続されるようにボンディングされる保護素子と、透光性樹脂からなり該保護素子および前記発光素子チップを被覆する樹脂パッケージとからなり、該保護素子は前記発光素子チップに印加され得る少なくとも逆方向電圧に対して前記発光素子チップを保護する素子であると共に、前記発光素子チップおよび前記保護素子が並置してそれぞれの両電極が前記第１および第２の端子電極上に直接接続して設けられることにより、前記絶縁性基板の表面から前記樹脂パッケージの表面までの高さが０ . ５ｍｍ以下の薄さに形成されている。
【００１０】
ここに保護素子とは、発光素子チップに印加され得る逆方向電圧を短絡したり、発光素子チップの動作電圧より高い所定の電圧以上の順方向電圧をショートさせ得る素子を意味し、ツェナーダイオードやトランジスタのダイオード接続、ＭＯＳＦＥＴのゲートとソースまたはドレインとを短絡した素子またはこれらの複合素子、ＩＣなどを含む。また、電極が直接接続されるとは、金線などのワイヤを介することなく、接触または導電性接着剤により接続されることを意味する。また、端子電極には発光素子が組み込まれる回路基板などと接続される電極部分と一体に形成されている金属部分のすべてを含む。
【００１１】
この構造にすることにより、ＬＥＤチップおよび保護素子の両方ともが直接第１および第２の端子電極に接続されているため、ワイヤボンディングを必要としない。そのため、ＬＥＤチップの上方にワイヤを張るスペースを必要としなくなり、非常に薄型のチップ型発光素子になると共に、保護素子が内蔵されているため、逆方向電圧や静電気のサージなどに対して破壊しにくい。
【００１２】
前記発光素子チップがチッ化ガリウム系化合物半導体からなり、前記保護素子がツェナーダイオードであれば、とくに逆電圧に弱く、また順方向でも高電圧の印加に弱いチッ化ガリウム系化合物半導体が用いられる青色系のチップ型発光素子において、逆方向電圧やサージ電圧などの印加に対して保護されるため好ましい。とくに保護素子としてツェナーダイオードが用いられることにより、発光素子チップに順方向にサージなどの高電圧が印加されてもツェナーダイオードのツェナー特性により、発光素子チップにダメージを与えることなく保護されると共に、通常の動作には何等の異常を来さない。ここにチッ化ガリウム系化合物半導体とは、III 族元素のＧａとＶ族元素のＮとの化合物またはIII 族元素のＧａの一部がＡｌ、Ｉｎなどの他のIII 族元素と置換したものおよび／またはＶ族元素のＮの一部がＰ、Ａｓなどの他のＶ族元素と置換した化合物からなる半導体をいう。
【００１３】
【発明の実施の形態】
つぎに、図面を参照しながら本発明の半導体発光素子について説明をする。
【００１４】
本発明の半導体発光素子は、その一実施形態の平面および断面の説明図が図１に示されるように、絶縁性基板１０の表面の両端部に第１および第２の端子電極１、２がそれらの一端部が一定間隙を有して対向するように設けられている。そして、第１および第２の端子電極１、２に直接ｎ側電極３９およびｐ側電極３８がそれぞれ接続されるようにＬＥＤチップ３がボンディングされている。さらに、第１および第２の端子電極１、２間に２つの電極がそれぞれ直接電気的に接続されるように保護素子であるツェナーダイオードチップ５がボンディングされ、第１および第２の端子電極１、２間にＬＥＤチップ３と逆方向になるように電気的に接続されている。そしてその周囲が樹脂パッケージ６により覆われている。
【００１５】
絶縁性基板１０は、たとえばガラスクロスに耐熱性のＢＴ樹脂を含浸させたＢＴレジンなどの絶縁性の基板からなっている。また、端子電極１、２は基板状態でその表面と裏面にスクリーン印刷などにより銀ペーストが塗布され、乾燥させることにより表面および裏面の電極が形成される。この電極形成は複数個のチップ分をまとめて大きな基板の状態で行われ、各チップの電極側の境界の側面にはスロットが形成されている。そのため、表面および裏面の電極を形成する際にスロット内にも銀ペーストが付着して、図１（ｂ）に示されるように、側面にも電極が形成され、表面から裏面に亘って端子電極が形成される。
【００１６】
ＬＥＤチップ３は、たとえば青色系（紫外線から黄色）の発光色を有するチップの一例の断面図が図３に示されるように形成される。すなわち、たとえばサファイア（Ａｌ2 Ｏ3 単結晶）などからなる基板３１の表面に、ＧａＮからなる低温バッファ層３２が０.０１〜０.２μｍ程度、クラッド層となるｎ形層３３が１〜５μｍ程度、ＩｎＧａＮ系（ＩｎとＧａの比率が種々変わり得ることを意味する、以下同じ）化合物半導体からなる活性層３４が０.０５〜０.３μｍ程度、ｐ形のＡｌＧａＮ系（ＡｌとＧａの比率が種々変わり得ることを意味する、以下同じ）化合物半導体層３５ａおよびＧａＮ層３５ｂからなるｐ形層（クラッド層）３５が０.２〜１μｍ程度、それぞれ順次積層されて、その表面に電流拡散層３７を介してｐ側電極３８が形成されている。また、積層された半導体層３３〜３５の一部が除去されて露出したｎ形層３３にｎ側電極３９が設けられることにより形成されている。
【００１７】
ツェナーダイオードチップ５は、通常のシリコン半導体などからなり、不純物濃度の高い半導体のｐｎ接合に大きい逆方向電圧を印加すると電子がトンネル効果によってｐｎ接合を通って流れる現象を利用したものである。この逆方向の電流が流れ始める電圧（ツェナー電圧）はその不純物濃度により設定される。したがって、このツェナー電圧をＬＥＤチップ３の動作電圧より高い所定の電圧に設定しておき、ＬＥＤチップ３とツェナーダイオードチップ５とが並列で逆方向になるように第１および第２の端子電極１、２に接続することにより、ＬＥＤチップ３の動作に支障を来すことはない。
【００１８】
このＬＥＤチップ３が図１に示されるように、裏向きにしてｎ側電極３９とｐ側電極３８がそれぞれ第１および第２の端子電極１、２の上にそれぞれ位置するように載置され、予め塗布されている銀ペーストなどの導電性接着剤により接着されている。なお、ボンディングの際にＬＥＤチップ３の表面でｎ側電極とｐ形層との短絡の虞れがあるときは、電極以外のＬＥＤチップ３の表面に絶縁性の保護膜を設けておくことにより、その虞れはなくなる。また、ツェナーダイオードチップ５は横向きにしてその正電極が第１の端子電極に接触し、負電極が第２の端子電極２と接触するように載置されて銀ペーストなどの導電性接着剤によりボンディングされている。なお、ＬＥＤチップ３も上下両面にそれぞれｎ側電極およびｐ側電極が設けられる構造のものであれば、ツェナーダイオードチップ５と同様に横向きにしてそれぞれの電極が直接第１および第２の端子電極と接触するようにダイボンディングされる。そして、ツェナーダイオードチップ５を含めたこれらの周囲がＬＥＤチップ３により発光する光を透過する透明または乳白色のエポキシ樹脂などによりモールドされることにより、樹脂パッケージ６で被覆された本発明のチップ型発光素子が得られる。
【００１９】
本発明のチップ型発光素子によれば、ツェナーダイオードチップ５が内蔵されて図４にその等価回路図が示されているように、ＬＥＤチップ３とツェナーダイオードチップ５とが並列で、かつ、その極性が相互に逆になるように接続されている。そのため、ＬＥＤチップ３を駆動する電源が交流電源であっても、ＬＥＤチップ３に順方向の電圧になる位相のときは、ツェナーダイオードチップ５には逆方向電圧でツェナー電圧より低い電圧であるため電流は流れず、ＬＥＤチップ３に電流が流れて発光する。また、交流電源がＬＥＤチップ３に逆方向の電圧になる位相のときは、ツェナーダイオードチップ５を介して電流が流れる。そのため、交流電圧がＬＥＤチップ３に対して逆方向の電圧の位相となるときでも、ＬＥＤチップ３には逆方向の電圧は殆ど印加されない。また、静電気が印加される場合、その静電気がＬＥＤチップ３の逆方向であればツェナーダイオードチップ５を介して放電し、ＬＥＤチップ３に順方向である場合はその電圧がツェナー電圧より高ければツェナーダイオードチップ５を介して放電するためＬＥＤチップ３を保護し、ツェナー電圧より低ければＬＥＤチップ３を介して放電するが、その電圧は低い電圧であるためＬＥＤチップ３を損傷することはない。その結果、逆方向の電圧や静電気のサージに対して弱いＬＥＤチップ３であってもＬＥＤチップ３に高い電圧が印加されず、ＬＥＤチップ３を破損したり、劣化させたりすることがない。
【００２０】
一方、本発明のチップ型発光素子では、ＬＥＤチップ３およびツェナーダイオードチップ５は共にそれらの電極が第１および第２の端子電極１、２に直接接続されているため、全然ワイヤボンディングを必要としない。そのため、基板１０からの高さはＬＥＤチップ３およびツェナーダイオード５の高さより僅かに高い範囲で収まり、基板表面からの高さＨが０.５ｍｍより低い超薄型にもなし得る。また、横方向もＬＥＤチップ３とツェナーダイオードとを並べてボンディングすることができ、ワイヤボンディングの必要がないため、全然大きくする必要はない。その結果、小形で超薄型の、しかも静電気や逆方向の電圧の印加に対して保護し得る保護素子が内蔵されたチップ型の発光素子が得られる。
【００２１】
前述の例では、保護素子としてツェナーダイオードチップを用いたが、チップでなくてパッケージングされた製品状のものを使用してもよい。また、ツェナーダイオードでなくても通常のダイオードでも、ＬＥＤチップに対する逆方向の電圧に対して保護することができる。さらに、ダイオードでなくても、トランジスタをダイオード接続したものや、ＭＯＳＦＥＴのゲートとソースまたはドレインとを接続したもの、またはこれらを組み合わせてツェナーダイオードと同様に両方向に保護する複合素子またはＩＣなど、ダイオードと同様にＬＥＤチップを保護することができる素子であればよい。
【００２２】
また、前述の例では、発光素子としてチッ化ガリウム系化合物半導体を用いた青色系の半導体発光素子であったが、チッ化ガリウム系化合物半導体はとくに逆方向の電圧や高電圧により破壊されやすいため効果が大きい。しかし、これに限定されるものではなく、ＧａＡｓ系、ＡｌＧａＡｓ系、ＡｌＧａＩｎＰ系、ＩｎＰ系などの赤色系や緑色系の発光素子についても、保護素子が設けられることにより同様に逆方向電圧や静電気に対して強い半導体発光素子が得られる。
【００２３】
さらに、前述の例では、ＬＥＤチップ３の周囲を被覆する樹脂パッケージ６がＬＥＤチップ３で発光する光に対して透明な樹脂だけで被覆する構造のチップ型発光素子であったが、図２に示されるように、周囲が反射ケース９で囲まれて、上方に光を集光させる構造のものでも同様に保護素子を内蔵し、超薄型とすることができる。なお、図２で図１と同じ部分には同じ符号を付してその説明を省略する。
【００２４】
【発明の効果】
本発明によれば、ＬＥＤチップと保護素子が直接、端子電極に接続されているため、逆方向電圧の印加や静電気による高電圧の印加に対しても損傷することがなく、信頼性が大幅に向上する超薄型の発光素子が得られる。その結果、携帯電話機やＰＨＳなどの携帯機器のスイッチボタンなどに用いられる光源を非常に薄くすることができ、携帯機器などのさらなる軽薄短小に寄与すると共に、半製品や製品の状態での取扱もアースバンドの使用や静電気除去の特別な注意を払う必要がなくなり、作業効率が大幅に向上する。
【図面の簡単な説明】
【図１】本発明の半導体発光素子の一実施形態の平面および断面の説明図である。
【図２】図１の変形例を示す図である。
【図３】図１のＬＥＤチップの一例の断面説明図である。
【図４】図１の半導体発光素子の接続関係の等価回路図である。
【図５】従来のチップ型発光素子の一例の斜視説明図である。
【符号の説明】
１ 第１の端子電極
２ 第２の端子電極
３ ＬＥＤチップ
５ ツェナーダイオードチップ
１０ 絶縁性基板[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a small chip light-emitting element that is suitable for use as a light source for illumination or display of portable electronic devices such as a mobile phone and a PHS and has a very low height from a substrate. More specifically, a protective element is provided to prevent the light emitting element from being damaged by static electricity even when a reverse voltage or a forward voltage higher than a predetermined voltage is applied to the light emitting element due to AC voltage driving or static electricity. The present invention relates to a chip type light emitting device.
[0002]
[Prior art]
With the downsizing of portable devices such as mobile phones and PHS, light-emitting elements used for them are required to be light and thin, and particularly thin chip-type light-emitting elements with low height are required.
[0003]
As shown in FIG. 5A, this type of small and thin chip-type light emitting element has terminal electrodes 1 and 2 formed on both ends of a substrate 10 and is connected to one terminal electrode 1 and is connected to one terminal electrode. A light emitting diode (hereinafter referred to as LED) chip 3 is bonded on the electrode to be a part, its lower electrode is directly connected to the terminal electrode 1, and its upper electrode is wire bonded to the other terminal electrode 2 by a gold wire 4. , Each is electrically connected. For example, as shown in FIG. 5B, the LED chip 3 has a pn junction surface (light emitting layer) 43 formed by joining an n-type semiconductor layer 41 made of GaAs or GaP and a p-type semiconductor layer 42, The electrodes 44 and 45 are provided on both surfaces thereof. On the surface side of the substrate 10 is formed a package 6 that covers and protects the LED chip 3 and the gold wire 4 with a resin made of a transparent or milky white epoxy resin or the like.
[0004]
Since such a light emitting element has a diode structure, an AC voltage is applied without applying a DC voltage between both electrodes by using a rectifying action in which no current flows even when a reverse voltage is applied. Accordingly, a method of using light that emits light when a current flows only when a forward voltage is generated by alternating current is also employed.
[0005]
[Problems to be solved by the invention]
In the conventional chip type light emitting device, the thickness of the LED chip is about 0.3 mm, and since wire bonding is performed, it is difficult to make the height from the substrate thinner than about 0.6 mm. Becomes about 0.8 to 1 mm. On the other hand, compound semiconductors such as GaAs, GaP, and gallium nitride that are used as light-emitting elements are vulnerable to voltages applied in the reverse direction or high voltages, and the semiconductor layer may be destroyed. In particular, gallium nitride-based compound semiconductors have a breakdown voltage in the reverse direction as low as about 50 V, and are particularly susceptible to breakdown with respect to an applied voltage in the reverse direction. Since the operating voltage is higher than that of the device, there is a problem in that the semiconductor light emitting device is damaged or its characteristics are deteriorated by application of an AC voltage.
[0006]
Further, even when driving is not performed by applying an AC voltage, when a large voltage such as a surge voltage is applied from the outside, there is a problem that a gallium nitride compound semiconductor is easily broken even at a forward voltage of about 150V.
[0007]
In order to prevent breakdown due to application of reverse voltage or static electricity, a Zener diode may be incorporated in the circuit in which the semiconductor light emitting element is incorporated in parallel with the semiconductor light emitting element in the opposite direction to the semiconductor light emitting element. . However, there is a need for space and man-hours to break down by static electricity during handling such as manufacturing process before being built into the circuit, transport process accompanying shipment, or when being built into the circuit board, or to incorporate diodes other than LEDs in the external circuit There is a problem that.
[0008]
The present invention has been made to solve such problems, and is a chip-type light emitting device that is small and very thin, but is strong against application of a surge voltage such as reverse voltage or static electricity, and easy to handle. The purpose is to provide.
[0009]
[Means for Solving the Problems]
The chip-type light emitting device according to the present invention includes an insulating substrate, and first and second terminal electrodes provided at both ends of the surface of the insulating substrate so that one end thereof is opposed to each other with a certain gap. A light emitting element chip in which the first and second electrodes are directly connected to the first and second terminal electrodes by a conductive adhesive, respectively, and two electrodes between the first and second terminal electrodes, respectively. A protective element that is bonded so as to be directly connected by a conductive adhesive, and a resin package that is made of a translucent resin and covers the protective element and the light emitting element chip. The protective element is attached to the light emitting element chip. with respect to the applied may at least reverse voltage is an element for protecting the light emitting element chip, the light emitting device chip and the protective element and the respective two electrodes juxtaposed first By provided directly connected to the spare on the second terminal electrode, the insulating height from the surface of the substrate to the surface of the resin package is 0. 5 mm is formed in the following thin.
[0010]
Here, the protective element means an element that can short-circuit a reverse voltage that can be applied to the light-emitting element chip, or can short-circuit a forward voltage that is higher than a predetermined voltage that is higher than the operating voltage of the light-emitting element chip. It includes a diode connection of a transistor, a device in which a gate and a source or drain of a MOSFET are short-circuited, or a composite device thereof, an IC, or the like. Moreover, that an electrode is directly connected means that it is connected by contact or a conductive adhesive without using a wire such as a gold wire. In addition, the terminal electrode includes all metal portions formed integrally with an electrode portion connected to a circuit board in which a light emitting element is incorporated.
[0011]
With this structure, since both the LED chip and the protection element are directly connected to the first and second terminal electrodes, wire bonding is not required. This eliminates the need for a space over the LED chip to provide a wire, resulting in a very thin chip-type light emitting device and a built-in protective device that can be destroyed against reverse voltage and electrostatic surges. Hateful.
[0012]
If the light-emitting element chip is made of a gallium nitride compound semiconductor and the protective element is a Zener diode, a blue gallium nitride compound semiconductor that is particularly weak against reverse voltage and weak against high voltage application in the forward direction is used. In the case of the chip type light emitting device, it is preferable because it is protected against application of reverse voltage or surge voltage. In particular, by using a Zener diode as a protective element, even if a high voltage such as a surge is applied to the light emitting element chip in the forward direction, the Zener diode is protected without damaging the light emitting element chip, There is no abnormality in normal operation. Here, the gallium nitride compound semiconductor is a compound in which a group III element Ga and a group V element N or a part of the group III element Ga is substituted with another group III element such as Al or In, and A semiconductor composed of a compound in which a part of N of the group V element is substituted with another group V element such as P or As.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Next, the semiconductor light emitting device of the present invention will be described with reference to the drawings.
[0014]
The semiconductor light emitting device of the present invention has first and second terminal electrodes 1 and 2 at both ends of the surface of the insulating substrate 10 as shown in FIG. Their one end portions are provided to face each other with a certain gap. The LED chip 3 is bonded so that the n-side electrode 39 and the p-side electrode 38 are directly connected to the first and second terminal electrodes 1 and 2, respectively. Further, a Zener diode chip 5 as a protection element is bonded so that the two electrodes are directly electrically connected between the first and second terminal electrodes 1 and 2, respectively, and the first and second terminal electrodes 1 and 2 are bonded. 2 is electrically connected to the LED chip 3 in the opposite direction. The periphery is covered with a resin package 6.
[0015]
The insulating substrate 10 is made of an insulating substrate such as BT resin in which a glass cloth is impregnated with a heat-resistant BT resin. Further, the terminal electrodes 1 and 2 are coated with a silver paste on the front and back surfaces by screen printing or the like in a substrate state, and dried to form front and back electrodes. This electrode formation is performed on a large substrate by putting together a plurality of chips, and a slot is formed on the side surface of the electrode side boundary of each chip. Therefore, when the front and back electrodes are formed, the silver paste adheres to the inside of the slot, and as shown in FIG. 1B, the electrodes are also formed on the side surfaces, and the terminal electrodes extend from the front surface to the back surface. Is formed.
[0016]
The LED chip 3 is formed, for example, as shown in FIG. 3 in a cross-sectional view of an example of a chip having a blue-based (ultraviolet to yellow) emission color. That is, for example, on the surface of the substrate 31 made of sapphire (Al 2 O 3 single crystal) or the like, the low-temperature buffer layer 32 made of GaN is about 0.01 to 0.2 μm, and the n-type layer 33 that becomes the cladding layer is 1 to 5 μm. The active layer 34 made of an InGaN-based compound semiconductor (meaning that the ratio of In and Ga can be changed variously, the same applies hereinafter) compound semiconductor is about 0.05 to 0.3 μm, p-type AlGaN-based (ratio of Al to Ga) P-type layer (cladding layer) 35 composed of a compound semiconductor layer 35a and a GaN layer 35b is sequentially stacked in a thickness of about 0.2 to 1 μm, and a current diffusion layer is formed on the surface thereof. A p-side electrode 38 is formed via 37. Further, the n-side electrode 39 is provided on the n-type layer 33 exposed by removing a part of the stacked semiconductor layers 33 to 35.
[0017]
The Zener diode chip 5 is made of a normal silicon semiconductor or the like, and utilizes a phenomenon in which electrons flow through the pn junction by a tunnel effect when a large reverse voltage is applied to a pn junction of a semiconductor having a high impurity concentration. The voltage at which the reverse current starts to flow (zener voltage) is set by the impurity concentration. Accordingly, the Zener voltage is set to a predetermined voltage higher than the operating voltage of the LED chip 3, and the first and second terminal electrodes 1 are arranged so that the LED chip 3 and the Zener diode chip 5 are in parallel and in opposite directions. By connecting to 2, the operation of the LED chip 3 is not hindered.
[0018]
As shown in FIG. 1, the LED chip 3 is placed face down so that the n-side electrode 39 and the p-side electrode 38 are positioned on the first and second terminal electrodes 1 and 2, respectively. It is adhered by a conductive adhesive such as silver paste applied in advance. When there is a risk of short circuit between the n-side electrode and the p-type layer on the surface of the LED chip 3 during bonding, an insulating protective film is provided on the surface of the LED chip 3 other than the electrodes. The fear disappears. Further, the Zener diode chip 5 is placed sideways so that its positive electrode is in contact with the first terminal electrode and its negative electrode is in contact with the second terminal electrode 2, and is attached by a conductive adhesive such as silver paste. Bonded. In addition, if the LED chip 3 has a structure in which an n-side electrode and a p-side electrode are provided on both upper and lower surfaces, respectively, the first and second terminal electrodes are arranged directly in the horizontal direction like the Zener diode chip 5. Die-bonded to contact Then, the periphery of these including the Zener diode chip 5 is molded with a transparent or milky white epoxy resin that transmits light emitted by the LED chip 3, so that the chip-type light emission of the present invention covered with the resin package 6 is performed. An element is obtained.
[0019]
According to the chip type light emitting device of the present invention, the Zener diode chip 5 is incorporated, and as shown in the equivalent circuit diagram of FIG. 4, the LED chip 3 and the Zener diode chip 5 are arranged in parallel, and They are connected so that their polarities are opposite to each other. Therefore, even if the power source for driving the LED chip 3 is an AC power source, the Zener diode chip 5 has a reverse voltage lower than the Zener voltage when the LED chip 3 has a phase that becomes a forward voltage. No current flows, and current flows through the LED chip 3 to emit light. Further, when the AC power supply has a phase in which the reverse voltage is applied to the LED chip 3, a current flows through the Zener diode chip 5. Therefore, even when the AC voltage is in the reverse voltage phase with respect to the LED chip 3, the reverse voltage is hardly applied to the LED chip 3. In addition, when static electricity is applied, if the static electricity is in the reverse direction of the LED chip 3, it is discharged through the Zener diode chip 5, and in the forward direction to the LED chip 3, if the voltage is higher than the Zener voltage, the Zener is discharged. The LED chip 3 is protected to discharge through the diode chip 5, and if it is lower than the Zener voltage, it is discharged through the LED chip 3. However, since the voltage is low, the LED chip 3 is not damaged. As a result, even if the LED chip 3 is weak against reverse voltage or electrostatic surge, a high voltage is not applied to the LED chip 3, and the LED chip 3 is not damaged or deteriorated.
[0020]
On the other hand, in the chip-type light emitting device of the present invention, both the LED chip 3 and the Zener diode chip 5 have their electrodes connected directly to the first and second terminal electrodes 1 and 2, and therefore require wire bonding at all. do not do. For this reason, the height from the substrate 10 is within a range slightly higher than the height of the LED chip 3 and the Zener diode 5, and the height H from the substrate surface can be made ultra-thin lower than 0.5 mm. Also, in the lateral direction, the LED chip 3 and the Zener diode can be bonded side by side, and there is no need for wire bonding. As a result, it is possible to obtain a chip-type light-emitting element that is small and ultra-thin and that has a built-in protective element that can protect against static electricity and application of a reverse voltage.
[0021]
In the above example, a Zener diode chip is used as the protective element, but a packaged product may be used instead of the chip. Moreover, even if it is not a Zener diode but a normal diode, it can protect with respect to the voltage of the reverse direction with respect to a LED chip. Furthermore, even if it is not a diode, a diode such as a diode-connected transistor, a MOSFET gate connected to a source or drain, or a composite element or IC that combines these to protect in both directions like a Zener diode Any element can be used as long as it can protect the LED chip.
[0022]
In the above example, a blue semiconductor light emitting device using a gallium nitride compound semiconductor as the light emitting device is used. However, a gallium nitride compound semiconductor is particularly susceptible to destruction by a reverse voltage or a high voltage. Great effect. However, the present invention is not limited to this, and red and green light emitting elements such as GaAs, AlGaAs, AlGaInP, and InP are also protected against reverse voltage and static electricity by providing protective elements. In contrast, a strong semiconductor light emitting device can be obtained.
[0023]
Furthermore, in the above-described example, the resin package 6 covering the periphery of the LED chip 3 is a chip-type light emitting element having a structure in which only the resin transparent to the light emitted from the LED chip 3 is covered. As shown in the figure, the protective element is similarly built in the structure in which the periphery is surrounded by the reflection case 9 and the light is condensed upward, and can be made ultra-thin. In FIG. 2, the same parts as those in FIG.
[0024]
【The invention's effect】
According to the present invention, since the LED chip and the protection element are directly connected to the terminal electrode, there is no damage even when a reverse voltage is applied or a high voltage is applied due to static electricity. An improved ultra-thin light-emitting element can be obtained. As a result, the light source used for switch buttons of portable devices such as mobile phones and PHS can be made very thin, contributing to further lightness and thinness of portable devices and the like, and handling in the state of semi-finished products and products There is no need to pay special attention to the use of an earth band or static electricity removal, greatly improving work efficiency.
[Brief description of the drawings]
FIG. 1 is an explanatory view of a plane and a cross section of an embodiment of a semiconductor light emitting device of the present invention.
FIG. 2 is a diagram showing a modification of FIG.
FIG. 3 is a cross-sectional explanatory diagram of an example of the LED chip of FIG. 1;
4 is an equivalent circuit diagram of a connection relationship of the semiconductor light emitting device of FIG. 1. FIG.
FIG. 5 is a perspective view illustrating an example of a conventional chip-type light emitting device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 1st terminal electrode 2 2nd terminal electrode 3 LED chip 5 Zener diode chip 10 Insulating board

Claims (1)

絶縁性基板と、該絶縁性基板の表面の両端部にそれらの一端部が一定間隙を有して対向するように設けられる第１および第２の端子電極と、前記第１および第２の端子電極にそれぞれ第１および第２の電極が導電性接着剤により直接接続される発光素子チップと、前記第１および第２の端子電極間に２つの電極がそれぞれ導電性接着剤により直接接続されるようにボンディングされる保護素子と、透光性樹脂からなり該保護素子および前記発光素子チップを被覆する樹脂パッケージとからなり、該保護素子は前記発光素子チップに印加され得る少なくとも逆方向電圧に対して前記発光素子チップを保護する素子であると共に、前記発光素子チップおよび前記保護素子が並置してそれぞれの両電極が前記第１および第２の端子電極上に直接接続して設けられることにより、前記絶縁性基板の表面から前記樹脂パッケージの表面までの高さが０ . ５ｍｍ以下の薄さに形成されてなるチップ型発光素子。An insulating substrate, first and second terminal electrodes provided at opposite ends of the surface of the insulating substrate such that one end thereof is opposed with a constant gap, and the first and second terminals A light emitting element chip in which the first and second electrodes are directly connected to the electrode by a conductive adhesive, and two electrodes are directly connected by the conductive adhesive between the first and second terminal electrodes, respectively. A protective element made of a transparent resin and a resin package covering the protective element and the light emitting element chip , the protective element against at least a reverse voltage that can be applied to the light emitting element chip wherein with the light emitting element is an element for protecting the chip, connecting the light emitting element chip and the protection device each both electrodes juxtaposed directly to the first and the second terminal electrodes Te By provided Te, height from the surface of the insulating substrate to the surface of the resin package is 0. 5 mm formed by forming the following thin chip type light emitting element.
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