JP4475726B2

JP4475726B2 - Photo coupler

Info

Publication number: JP4475726B2
Application number: JP2000087701A
Authority: JP
Inventors: 正仁古屋
Original assignee: Citizen Electronics Co Ltd
Current assignee: Citizen Electronics Co Ltd
Priority date: 2000-03-27
Filing date: 2000-03-27
Publication date: 2010-06-09
Anticipated expiration: 2020-03-27
Also published as: JP2001274453A

Description

【０００１】
【発明の属する技術分野】
本発明は、電気・電子機器に使用され、入出力側からの信号に応答して非接触で出力側から信号を得ることができるフォトカプラに関する。
【０００２】
【従来の技術】
従来のフォトカプラの構造について説明する。図７は、従来のフォトカプラの要部断面図、図８は、図７のフォトカプラの平面図、図９は、図７の発光素子の構成を説明する図で、図９（ａ）は発光素子の側面図、図９（ｂ）は上面図、図９（ｃ）は図９（ｂ）のＡ−Ａ線断面図である。
【０００３】
図７及び図８において、符号１は光透過性樹脂よりなる透光性基板である。前記透光性基板１の上面側には金メッキされた第１の配線パターン２が形成されている。前記第１の配線パターン２の一方の端部に形成されたダイボンドパターン２ａは、発光素子の大きさより大き目に形成されている。他方の端部２ｂにはワイヤー７をワイヤーボンドする。また、前記透光性基板１の下面側には金メッキされた第２の配線パターン３が形成されている。前記第２の配線パターン３は、一方の端部３ａと他方の端部３ｂとの間に発光素子６の発光部６ｃからの光を透過する窓部４が形成されている。
【０００４】
前記第１の配線パターン２のダイボンドパターン２ａにダイボンドベースト５（銀ペースト等）で発光素子６（ＬＥＤ等）をダイボンドし、ワイヤー７（Ａｕ線）で他方の配線パターン２ｂにワイヤーボンディングする。更に、前記第２の配線パターン３の一方の端部３ａと他方の端部３ｂとの間の窓部４に跨がって受光素子８（フォトトランジスタ等）を半田９で半田付けして実装し電気的に接続する。
【０００５】
上記したように、前記発光素子６と受光素子７を光学的に結合する様に対向配置する。発光素子６とワイヤー７とを透光性樹脂１０にて被覆し、該透光性樹脂１０及び受光素子８を封止樹脂１１にて封止する。
【０００６】
図９において、発光素子６の構成は、略直方体形状の発光素子６の上下面にはそれぞれ上電極（Ａｕ／オーミック）６ａ、下電極（Ａｕ／オーミック）６ｂが形成され、上電極６ａ側にジャンクション（発光部）６ｃが配設されている。
【０００７】
上記した構成のフォトカプラにおいて、発光素子６のジャンクション（発光部）６ｃからの光は、オーミック部で吸収され、残光が上電極６ａのＡｕ面で反射されるが、上電極６ａの占める面積は、発光素子６の上面全体の略四角形状の平面からすると極めて狭いため、図９（ｃ）に示す様に発光素子６からの光は殆ど上方（矢印Ａ方向）に抜けてしまう。この上方に抜けた光は、図７に示す様に、透光性樹脂１０と封止樹脂１１との境界面Ｂで２つの樹脂の屈折率の差により反射し、光路Ｃに示すように透光性樹脂１０及び透光性基板１を透過し、前記窓部４を経て受光素子８へ到達することになる。
【０００８】
【発明が解決しようとする課題】
前述したように、発光素子からの光は透光性基板を通して受光素子に伝達させていた。受光素子に到達する光は、主に発光素子から直接入る光と発光素子周辺の透光性樹脂からの反射光である。発光素子の下が全て配線パターンのため光が通らず、その他の透過する部分からしか光が通らない。また、発光素子周辺の透光性樹脂による反射光も距離が遠いので光の伝達効率が悪い。従って、受光素子への光結合効率の向上が課題になる。
【０００９】
本発明は上記従来の課題に鑑みなされたものであり、その目的は、光結合特性が優れたフォトカプラを提供するものである。
【００１０】
【課題を解決するための手段】
上記目的を達成するために、本発明におけるフォトカプラは、透光性基板の上面側に配設された第1の配線パターンの一方の端部にダイボンドし、他方の端部にワイヤーボンディングする発光素子と、前記透光性基板の下面側に配設された第2の配線パターンの一方の端部と他方の端部との間にあって発光部からの光を透過させる窓部に跨がって実装した受光素子と、前記発光素子と前記受光素子を光学的に結合する様に対向配置し、前記発光素子を透光性樹脂にて被覆し、該透光性樹脂及び前記受光素子を封止樹脂にて封止したフォトカプラにおいて、前記発光素子は、ジャンクション（発光部）を前記透光性基板に対して反対側に向く様に配すると共に前記窓部を避けた位置に配置されており、且つ前記発光素子には、上電極を覆う様に前記ジャンクション（発光部）側の素子上面を金属反射部材で被覆したことを特徴とするものである。
【００１１】
また、前記発光素子はその上面のジャンクション（発光部）側から見た時四角い形状を成しているもので、前記金属反射部材で被覆した領域は、前記ジャンクション（発光部）の前記四角い平面形状の略全面を覆うものであり、前記発光素子からの光は、前記金属反射部材面で殆どを反射し、該反射光は前記発光素子の側面から前記透光性樹脂及び前記透光性基板を透過し、前記窓部から前記受光素子へ到達することを特徴とするものである。
【００１２】
また、前記発光素子はその上面のジャンクション（発光部）側から見た時四角い形状を成しているもので、前記金属反射部材で被覆した領域は、前記ジャンクション（発光部）の前記四角い平面形状の前記窓部側の略半分を覆うものであり、前記発光素子からの光は、前記金属反射部材面で略半分が反射される第1の反射光と、一方、前記金属反射部材で覆われていない略半分の領域は、光が上方に抜け前記透光性樹脂と前記封止樹脂の境界面で反射される第2の反射光となり、前記第1の反射光と前記第2の反射光は共に前記透光性樹脂及び前記透光性基板を透過し、前記窓部から前記受光素子へ到達することを特徴とするものである。
【００１３】
また、前記金属反射部材は、Ａｕ被膜であることを特徴とするものである。
【００１４】
【発明の実施の形態】
以下図面に基づいて本発明におけるフォトカプラについて説明する。図１〜図３は、本発明の第１の実施の形態であるフォトカプラに係わり、図１は、フォトカプラの要部断面図、図２は、第１のフォトカプラの平面図、図３は、図１の発光素子の構成を説明する図で、図３（ａ）は発光素子の側面図、図３（ｂ）は上面図、図３（ｃ）は図３（ｂ）のＡ−Ａ線断面図である。図において、従来技術と同一部材は同一符号で示す。
【００１５】
図１〜図３において、従来技術と異なるところは、図３に示す様に、前記発光素子６の上電極６ａにおいて、ジャンクション（発光部）６ｃの上面に位置し四角い平面形状の略全面を覆う様に金属反射部材であるＡｕ被膜１２を形成したことである。
【００１６】
上記構成により、図１に示すように、発光素子６のジャンクション（発光部）６ｃから出射した光は上方に向かうが、発光素子６の上面側はＡｕ被膜１０で四角い平面形状の殆どが覆われているため、殆どの光はＡｕ被膜１２で反射し下方向（図３（ｃ）のＤ方向）へ向かい、光路Ｃに示すように透光性樹脂１０及び透光性基板１を透過し、前記窓部４から受光素子８へ到達する。
【００１７】
上記した構成により、発光素子６のジャンクション（発光部）６ｃからの光は、発光素子６の上面の極めて近い距離で反射されるので反射効率は極めて良い。また、Ａｕ被膜１２により高反射率を確保することができる。
【００１８】
また、発光素子６の構造において、素子の発光効率（電流分布等）が低下せず、製造工程に影響がでないレベルで小さいオーミックとする。
【００１９】
図４〜図６は、本発明の第２の実施の形態であるフォトカプラに係わり、図４は、フォトカプラの要部断面図、図５は、第４のフォトカプラの平面図、図６は、図４の発光素子の構成を説明する図で、図６（ａ）は発光素子の側面図、図６（ｂ）は上面図、図６（ｃ）は図６（ｂ）のＡ−Ａ線断面図である。
【００２０】
前述した第１の実施形態と異なるところは、図６に示す様に、前記発光素子６上電極６ａにおいて、ジャンクション（発光部）６ｃの上面に位置し四角い平面形状の略半分の面を覆う様にＡｕ被膜１２を形成したことである。そのため、発光素子６からの光は、Ａｕ被膜１２で略半分が反射され下方向（図６（ｃ）の矢印Ｄ方向）へ向かい第１の反射光となる。一方、Ａｕ被膜１２で覆われていない略半分の領域は、発光素子６からの光が上方向（図６（ｃ）の矢印Ａ方向）に抜けて前記透光性樹脂１０と封止樹脂１１の境界面Ｂで反射される第２の反射光となる。前記第１の反射光と第２の反射光は共に透光性樹脂１０及び透光性基板１を透過し、前記窓部４から受光素子８へ到達する。
【００２１】
上記した構成により、発光素子６の略半分を覆っているＡｕ被膜１２からの第１の反射光は、極めて近い距離で反射されるので高反射率を確保できる。一方、Ａｕ被膜１２で覆われていない略半分から上方に抜け境界面Ｂで反射される第２の反射光は、受光素子８から遠い側の伝達効率を考え、透光性樹脂１０からの反射光を利用する。
【００２２】
【発明の効果】
以上説明したように、本発明によれば、発光素子の上面の略全面又は略半分を金属反射部材であるＡｕ被膜で覆うことにより、発光素子の発光効率を低下せず、Ａｕ被膜で覆われた部分の光はジャンクション（発光部）から極めて近い距離で反射されて受光素子へ到達するため、高反射効率が確保でき、受光素子への光結合効率を大幅に向上させたフォトカプラを提供することができる。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態に係わるフォトカプラの要部断面図である。
【図２】図１のフォトカプラの平面図である。
【図３】図１の発光素子の構成を説明する図で、図３（ａ）は発光素子の側面図、図３（ｂ）は上面図、図３（ｃ）は図３（ｂ）のＡ−Ａ線断面図である。
【図４】本発明の第２の実施の形態に係わるフォトカプラの要部断面図である。
【図５】図４のフォトカプラの平面図である。
【図６】図４の発光素子の構成を説明する図で、図６（ａ）は発光素子の側面図、図６（ｂ）は上面図、図６（ｃ）は図６（ｂ）のＡ−Ａ線断面図である。
【図７】従来のフォトカプラの要部断面図である。
【図８】図７のフォトカプラの平面図である。
【図９】図７の発光素子の構成を説明する図で、図９（ａ）は発光素子の側面図、図９（ｂ）は上面図、図９（ｃ）は図９（ｂ）のＡ−Ａ線断面図である。
【符号の説明】
１透光性基板
２第１の配線パターン
２ａダイボンドパターン
３第２の配線パターン
４窓部
５ダイボンドペースト
６発光素子（ＬＥＤ）
６ａ上電極
６ｂ下電極
６ｃジャンクション（発光部）
７ワイヤー
８受光素子（フォトトランジスタ）
１０透光性樹脂
１１封止樹脂
１２Ａｕ被膜
Ｂ透光性樹脂境界面（反射面）
Ｃ光路[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photocoupler that is used in electrical and electronic equipment and can obtain a signal from an output side in a non-contact manner in response to a signal from an input / output side.
[0002]
[Prior art]
The structure of a conventional photocoupler will be described. 7 is a cross-sectional view of a main part of a conventional photocoupler, FIG. 8 is a plan view of the photocoupler of FIG. 7, FIG. 9 is a diagram illustrating the configuration of the light-emitting element of FIG. 7, and FIG. 9B is a side view of the light-emitting element, FIG. 9B is a top view, and FIG. 9C is a cross-sectional view taken along line AA in FIG. 9B.
[0003]
7 and 8, reference numeral 1 denotes a light-transmitting substrate made of a light-transmitting resin. A gold-plated first wiring pattern 2 is formed on the upper surface side of the translucent substrate 1. The die bond pattern 2a formed at one end of the first wiring pattern 2 is formed larger than the size of the light emitting element. The wire 7 is wire-bonded to the other end 2b. A second wiring pattern 3 plated with gold is formed on the lower surface side of the translucent substrate 1. In the second wiring pattern 3, a window portion 4 that transmits light from the light emitting portion 6 c of the light emitting element 6 is formed between one end portion 3 a and the other end portion 3 b.
[0004]
A light-emitting element 6 (LED or the like) is die-bonded to the die bond pattern 2a of the first wiring pattern 2 with a die-bond base 5 (silver paste or the like), and wire-bonded to the other wiring pattern 2b with a wire 7 (Au wire). Further, the light receiving element 8 (phototransistor or the like) is soldered and mounted across the window 4 between the one end 3a and the other end 3b of the second wiring pattern 3. Then connect them electrically.
[0005]
As described above, the light emitting element 6 and the light receiving element 7 are arranged to face each other so as to be optically coupled. The light emitting element 6 and the wire 7 are covered with a translucent resin 10, and the translucent resin 10 and the light receiving element 8 are sealed with a sealing resin 11.
[0006]
In FIG. 9, the structure of the light emitting element 6 is such that an upper electrode (Au / ohmic) 6a and a lower electrode (Au / ohmic) 6b are formed on the upper and lower surfaces of the substantially rectangular parallelepiped light emitting element 6, respectively. A junction (light emitting portion) 6c is disposed.
[0007]
In the photocoupler configured as described above, light from the junction (light emitting portion) 6c of the light emitting element 6 is absorbed by the ohmic portion, and afterglow is reflected by the Au surface of the upper electrode 6a, but the area occupied by the upper electrode 6a. Is extremely narrow when viewed from the substantially square plane of the entire top surface of the light emitting element 6, and therefore light from the light emitting element 6 almost escapes upward (in the direction of arrow A) as shown in FIG. 9C. As shown in FIG. 7, the light that has passed through the upper part is reflected by the difference in refractive index between the two resins at the boundary surface B between the translucent resin 10 and the sealing resin 11, and is transmitted as shown in the optical path C. The light passes through the light-transmitting resin 10 and the light-transmitting substrate 1 and reaches the light receiving element 8 through the window 4.
[0008]
[Problems to be solved by the invention]
As described above, the light from the light emitting element is transmitted to the light receiving element through the translucent substrate. The light that reaches the light receiving element is mainly light that directly enters from the light emitting element and reflected light from the translucent resin around the light emitting element. Since all the wiring pattern is under the light emitting element, light does not pass through it, and light can pass only through other transmitting parts. In addition, since the light reflected by the translucent resin around the light emitting element is also far away, the light transmission efficiency is poor. Therefore, improvement of the optical coupling efficiency to the light receiving element becomes a problem.
[0009]
The present invention has been made in view of the above-described conventional problems, and an object thereof is to provide a photocoupler having excellent optical coupling characteristics.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the photocoupler according to the present invention emits light by die-bonding to one end of the first wiring pattern disposed on the upper surface side of the light-transmitting substrate and wire-bonding to the other end. The element and the second wiring pattern disposed on the lower surface side of the translucent substrate are between one end portion and the other end portion, and straddle the window portion that transmits light from the light emitting portion. The mounted light receiving element and the light emitting element and the light receiving element are arranged so as to be optically coupled, the light emitting element is covered with a light transmitting resin, and the light transmitting resin and the light receiving element are sealed. In the photocoupler sealed with resin, the light emitting element is arranged so that the junction (light emitting part) faces the opposite side with respect to the translucent substrate and avoids the window part. In addition, the light emitting element has a front so as to cover the upper electrode. The element upper surface of the junction (light emitting portion) side is characterized in that coated with metallic reflecting member.
[0011]
Further, the light emitting element by way forms a rectangular shape when viewed from the upper surface of the junction (light emitting portion) side, the area coated with the metal reflecting member, said rectangular planar shape of the junction (light emitting portion) substantially is intended to cover the entire surface, light from the light emitting element, the reflected almost a metallic reflecting member surface, reflected light is the light-transmitting resin and the light-transmissive substrate from the side surface of the light emitting element The light passes through and reaches the light receiving element from the window.
[0012]
Further, the light emitting element by way forms a rectangular shape when viewed from the upper surface of the junction (light emitting portion) side, the area coated with the metal reflecting member, said rectangular planar shape of the junction (light emitting portion) is intended to cover the window portion substantially half of the light from the light emitting element, the first and the reflected light substantially half the metal reflecting member surface is reflected, whereas, covered with the metal reflective member substantially half area is not, the light becomes the second reflected light reflected by the boundary surface of the sealing resin and the translucent resin omission upward, the second reflected light and the first reflected light are those both transmitted through the translucent resin and the translucent substrate, characterized in that it reach the light receiving element from the window.
[0013]
The metal reflecting member is an Au coating.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The photocoupler according to the present invention will be described below with reference to the drawings. 1 to 3 relate to a photocoupler according to a first embodiment of the present invention. FIG. 1 is a cross-sectional view of the main part of the photocoupler. FIG. 2 is a plan view of the first photocoupler. FIG. 3 is a diagram for explaining the configuration of the light-emitting element of FIG. 1, FIG. 3A is a side view of the light-emitting element, FIG. 3B is a top view, and FIG. It is A sectional view. In the figure, the same members as those in the prior art are denoted by the same reference numerals.
[0015]
1 to 3, the difference from the prior art is that, as shown in FIG. 3, the upper electrode 6a of the light emitting element 6 is located on the upper surface of the junction (light emitting portion) 6c and covers substantially the entire surface of a square planar shape. In other words, the Au coating 12 as a metal reflecting member was formed.
[0016]
1, the light emitted from the junction (light emitting portion) 6c of the light emitting element 6 goes upward, but the upper surface side of the light emitting element 6 is almost covered with the Au coating 10 with a square planar shape. Therefore, most of the light is reflected by the Au coating 12, travels downward (D direction in FIG. 3 (c) ), passes through the translucent resin 10 and the translucent substrate 1 as indicated by the optical path C, The light reaches the light receiving element 8 from the window 4.
[0017]
With the configuration described above, the light from the junction (light emitting portion) 6c of the light emitting element 6 is reflected at a very close distance on the upper surface of the light emitting element 6, so that the reflection efficiency is very good. Moreover, a high reflectance can be ensured by the Au coating 12.
[0018]
Further, in the structure of the light emitting element 6, the light emitting efficiency (current distribution or the like) of the element is not lowered, and the ohmic is small at a level that does not affect the manufacturing process.
[0019]
4 to 6 relate to a photocoupler according to a second embodiment of the present invention. FIG. 4 is a cross-sectional view of the main part of the photocoupler. FIG. 5 is a plan view of the fourth photocoupler. FIG. 6 is a diagram for explaining the configuration of the light-emitting element in FIG. 4, FIG. 6A is a side view of the light-emitting element, FIG. 6B is a top view, and FIG. It is A sectional view.
[0020]
A difference from the first embodiment described above is that, as shown in FIG. 6, the upper electrode 6a of the light emitting element 6 is located on the upper surface of the junction (light emitting portion) 6c and covers a substantially half surface of a square planar shape. In other words, the Au coating 12 was formed. Therefore, light from the light emitting element 6 is substantially half Au film 12 is first reflected light directed downward is reflected (arrow D direction in Figure 6 (c)). On the other hand, almost half of the region not covered with the Au film 12, the light upward from the light emitting element 6 to come off the translucent resin 10 and the sealing resin (FIG. 6 (c) the direction of arrow A in) 11 The second reflected light is reflected at the boundary surface B. Both the first reflected light and the second reflected light are transmitted through the translucent resin 10 and the translucent substrate 1 and reach the light receiving element 8 from the window portion 4.
[0021]
With the above-described configuration, the first reflected light from the Au coating 12 covering substantially half of the light emitting element 6 is reflected at a very close distance, so that a high reflectance can be secured. On the other hand, the second reflected light that passes upward from substantially half that is not covered with the Au coating 12 and is reflected by the boundary surface B reflects from the translucent resin 10 in consideration of the transmission efficiency far from the light receiving element 8. Use light.
[0022]
【The invention's effect】
As described above, according to the present invention, by covering substantially the entire upper surface or substantially half of the upper surface of the light emitting element with the Au film that is a metal reflecting member, the light emitting efficiency of the light emitting element is not lowered and the light emitting element is covered with the Au film. The reflected light is reflected at a very close distance from the junction (light emitting part) and reaches the light receiving element, so that a high reflection efficiency can be secured, and a photocoupler with greatly improved optical coupling efficiency to the light receiving element is provided. be able to.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a main part of a photocoupler according to a first embodiment of the present invention.
FIG. 2 is a plan view of the photocoupler of FIG.
3A and 3B illustrate a structure of the light-emitting element in FIG. 1. FIG. 3A is a side view of the light-emitting element, FIG. 3B is a top view, and FIG. 3C is a view in FIG. It is AA sectional view.
FIG. 4 is a cross-sectional view of a main part of a photocoupler according to a second embodiment of the present invention.
FIG. 5 is a plan view of the photocoupler of FIG. 4;
6A and 6B are diagrams illustrating a structure of the light-emitting element in FIG. 4, in which FIG. 6A is a side view of the light-emitting element, FIG. 6B is a top view, and FIG. 6C is a view in FIG. It is AA sectional view.
FIG. 7 is a cross-sectional view of a main part of a conventional photocoupler.
8 is a plan view of the photocoupler of FIG. 7. FIG.
9A and 9B illustrate a structure of the light-emitting element in FIG. 7, in which FIG. 9A is a side view of the light-emitting element, FIG. 9B is a top view, and FIG. 9C is a view in FIG. It is AA sectional view.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Translucent board | substrate 2 1st wiring pattern 2a Die-bonding pattern 3 2nd wiring pattern 4 Window part 5 Die-bonding paste 6 Light emitting element (LED)
6a Upper electrode 6b Lower electrode 6c Junction (light emitting part)
7 Wire 8 Light receiving element (phototransistor)
10 Translucent resin 11 Sealing resin 12 Au coating B Translucent resin boundary surface (reflection surface)
C light path

Claims

A light emitting element that is die-bonded to one end portion of the first wiring pattern disposed on the upper surface side of the translucent substrate and wire-bonded to the other end portion, and disposed on the lower surface side of the translucent substrate. A light receiving element mounted between one end portion and the other end portion of the second wiring pattern and straddling a window portion that transmits light from the light emitting portion, and the light emitting element and the light receiving element are optically connected. In a photo coupler in which the light-emitting element is covered with a light-transmitting resin and the light-transmitting resin and the light-receiving element are sealed with a sealing resin.
The light-emitting element is disposed such that a junction (light-emitting part) faces away from the light-transmitting substrate and is located away from the window part, and the light-emitting element includes an upper electrode. photocoupler, characterized in that the junction (light emitting portion) side of the element top surface to cover the coated with metallic reflecting member.

The light emitting device in which forms a square shape when viewed from the upper surface of the junction (light emitting portion) side, the area coated with the metal reflecting member is approximately the square planar shape of the junction (light emitting portion) is intended to cover the entire surface, light from the light emitting element, the reflected almost a metallic reflecting member surface, reflected light is transmitted through the translucent resin and the translucent substrate from the side surface of the light emitting element 2. The photocoupler according to claim 1, wherein the photocoupler reaches the light receiving element from the window.

The light emitting device in which forms a square shape when viewed from the upper surface of the junction (light emitting portion) side, the area coated with the metal reflecting member, the said rectangular planar shape of the junction (light emitting portion) It is intended to cover the substantially half of the window portion, light from the light emitting element, the first and the reflected light is approximately half reflected by the metal reflecting member surface, while not covered by the metal reflecting member substantially half area, the light becomes the second reflected light reflected by the boundary surface of the sealing resin and the translucent resin omission upward, the first and the second reflected light and the reflected light are both the translucent resin and passes through the transparent substrate, the photo-coupler of claim 1, wherein the reaching to the light receiving element from the window.

The metal reflecting member photocoupler according to claim 1, characterized in that a Au film.