JP2001168377A - Photocoupler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized photocoupler which is inexpensive and has high light transfer efficiency. SOLUTION: The photocoupler having a light emitting element and light receiving elements optically coupled with each other has the light emitting element provided on an insulating layer formed on a semiconductor substrate and the Light receiving elements formed on the semiconductor substrates while surrounding the light emitting element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocoupler, and more particularly to a photocoupler having improved light transmission efficiency between a light emitting element and a light receiving element.

[0002]

2. Description of the Related Art FIGS. 3 and 4 are sectional views showing the structure of a conventional photocoupler. In FIG. 3, the light emitting element 1 and the light receiving element 2 are arranged in parallel on the same insulating substrate 3 in the horizontal direction, and the periphery thereof is covered with a transparent resin 3 that optically couples the light emitting element 1 and the light receiving element 2. Further, the whole of the light emitting element 1, the light receiving element 2, and the transparent resin 4 are sealed with a mold resin 5.

The light emitted from the light emitting element 1 is
The light is reflected on the light receiving element 2 directly through the transparent resin 4 or at the interface between the transparent resin 4 and the mold resin 5,
The light receiving element 2 outputs an electric signal corresponding to the intensity of the emitted light.

In this case, the light emitting element 1 is composed of a semiconductor PN junction, and when a bias is applied between the PN junctions, electrons and holes recombine to emit light. The light is mainly emitted from the side surface of the light emitting element 1 which is a surface perpendicular to the interface of the PN junction.

In FIG. 4, a light emitting element 1 is die-bonded to an insulating substrate 3, a light receiving element 2 is die bonded to an insulating substrate 6, and the light emitting element 1 and the light receiving element 2 are arranged to face each other.

A space between the light emitting element 1 and the light receiving element 2 is filled with a transparent resin 4 for optically coupling the two, and the light emitting element 1 and the external electrode 7 are connected by a thin metal wire 8. The light-emitting element 1 can be energized via. Then, the whole of the light emitting element 1, the light receiving element 2, and the transparent resin 4 are sealed with the mold resin 5.

In this case, the light emitted from the light emitting element 1 is evenly applied to the light receiving element 2 via the transparent resin 4, and the light receiving element 2 outputs an electric signal corresponding to the intensity of the applied light. In this structure, the distance between the light-emitting element 1 and the light-receiving element 2 can be reduced to a certain distance in order to increase the light transmission efficiency.

[0008]

However, such a photocoupler has the following problems. FIG.
In the photocoupler shown in (1), light emitted from the light emitting element 1 is mainly emitted from the side surface of the light emitting element 1 which is a plane perpendicular to the interface of the PN junction.

Accordingly, the light emitted from the light emitting element 1 to the light receiving element 2 efficiently reaches the light receiving element 2, but the light emitted to the opposite side of the light receiving element 2 The light travels a long distance before reaching the light receiving element 2 after being reflected at the interface, and the attenuation of light intensity increases,
As a result, the light transmission efficiency decreases.

Further, since the light emitting element 1 and the light receiving element 2 are arranged in the horizontal direction, the size of the entire photocoupler becomes large.

In the photocoupler shown in FIG. 4, the light emitting element 1 and the light receiving element 2 are die-bonded to separate insulating substrates 3 and 6, respectively, and the light emitting element 1 and the external electrode 7 are connected to the thin metal wires 8 respectively.
It is necessary to face each other after the connection and fill the transparent resin 4 between them, which complicates the manufacturing process and increases the cost.

The distance between the light emitting element 1 and the light receiving element 2 is
Due to the presence of the thin metal wire 8 connecting the light emitting element 1 and the external electrode 7, the limit is several tens of microns, which limits the light transmission efficiency.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. A plurality of light-receiving elements are arranged so as to surround a light-emitting element, and a conductive layer in which the back surface of the light-emitting element is in contact is provided. An object of the present invention is to provide a small-sized photocoupler which is inexpensive, has high light transmission efficiency, and is made of an electrode.

[0014]

According to a first aspect of the present invention, in a photocoupler in which a light emitting element and a light receiving element are optically coupled, the light emitting element is formed on an insulating layer formed on a semiconductor substrate. A plurality of the light receiving elements are provided on the semiconductor substrate, and are arranged so as to surround the light emitting elements.

According to a second aspect of the present invention, a conductive layer is provided between the light-emitting element and the insulating layer so that the light-emitting element can conduct electricity, and the conductive layer is used as an electrode of the light-emitting element. A photocoupler according to claim 1, wherein

According to a third aspect of the present invention, in the photocoupler in which the light emitting element and the light receiving element are optically coupled, the light emitting element is provided on an insulating substrate, and the light receiving element is provided on the insulating substrate in a plurality. The photocoupler is provided so as to surround the light emitting element.

According to a fourth aspect of the present invention, a conductive layer is provided between the light emitting element and the insulating substrate so that the light emitting element can be energized, and this conductive layer is used as an electrode of the light emitting element. A photocoupler according to claim 3, wherein

According to a fifth aspect of the present invention, there is provided the photocoupler according to any one of the first to fourth aspects, wherein the plurality of light receiving elements are electrically connected.

According to a sixth aspect of the present invention, the light receiving element is a photodiode array in which a plurality of photodiodes formed on the same semiconductor substrate are electrically connected. To a photocoupler according to claim 5.

[0020]

Next, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same parts as those in FIGS. 3 and 4 are denoted by the same reference numerals, and description thereof will be omitted as appropriate. FIG. 1A is a plan view showing the configuration of the first embodiment of the present invention, and FIG.
It is A 'sectional drawing.

1A and 1B, a rectangular silicon semiconductor substrate 10 is die-bonded to an insulating substrate 3 (for example, a glass epoxy substrate).
A light emitting element 1 is provided at a central portion of the semiconductor substrate 1 so that a plurality of light receiving elements 2 surround the light emitting element 1.
0 is formed by a well-known semiconductor manufacturing technique.

Note that one electrode (not shown) is formed on the front surface of the light emitting element 1, and the back surface of the light emitting element 1 is the other electrode. When the two electrodes are energized, the light emitting element 1 emits light. Radiate.

Then, an insulating layer 11 made of, for example, silicon dioxide is formed on the semiconductor substrate 10, and the light emitting element 1
Is die-bonded on the conductive layer 12 patterned on the insulating layer 11 by a conductive paste. In this case, the conductive layer 12 is a thin film layer of, for example, aluminum or copper.

Then, one electrode (not shown) formed on the surface of the light emitting element 1 and the external electrode 7 are connected (wire-bonded) by the thin metal wire 8, and the conductive layer 12 and the external electrode 70 are connected by the thin metal wire 80. Have been.

In this case, the back surface of the light emitting element 1 is
, The conductive layer 12 functions as the other electrode of the light emitting element 1, and causes the light emitting element 1 to emit light by energizing the external electrodes 7 and 70.

The plurality of light receiving elements 2 formed on the semiconductor substrate 10 are electrically connected in series by a wiring pattern (not shown) on the semiconductor substrate 10 so that their electric signals can be taken out. . The transparent resin 4 covers the light emitting element 1 and the plurality of light receiving elements 2, and the periphery thereof is sealed with a mold resin 5.

Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 2A is a plan view showing the configuration of the second embodiment of the present invention, and FIG.
It is A 'sectional drawing.

2 (a) and 2 (b), the light emitting element is die-bonded with a conductive paste onto a conductive layer 12 formed on the surface of the insulating substrate 3, and the light receiving element 2 is formed.
a, 2b, 2c, 2d are die-bonded to the insulating substrate 3 so as to surround the light emitting element 1.

Then, one electrode (not shown) formed on the surface of the light emitting element 1 and the external electrode 7 are connected by a thin metal wire 8, and the conductive layer 12 and the external electrode 70 are connected by a thin metal wire 80.
Connected by

In this case, the back surface of the light emitting element 1 is
, The conductive layer 12 functions as the other electrode of the light emitting element 1, and the light emitting element 1 emits light when the external electrodes 7 and 70 are energized.

The light receiving elements 2a and 2d are connected by a thin metal wire 13a, the light receiving elements 2a and 2b are connected by a thin metal wire 13b, the light receiving elements 2b and 2c are connected by a thin metal wire 13c. 2
Thin metal wires 81 and 82 are connected to c and 2d, respectively.

Then, external electrodes (not shown) are connected to the thin metal wires 81 and 82, and electric signals generated by the serially connected light receiving elements 2a, 2b, 2c and 2d are taken out through these external electrodes. It is. Then, the transparent resin 4 covers the light emitting element 1 and the light receiving elements 2a, 2b, 2c, 2d,
Further, the periphery thereof is sealed with a mold resin 5.

In the photocoupler shown in FIGS. 1 and 2, light is mainly emitted from the side surface of the light emitting element. However, since a plurality of light receiving elements are arranged so as to surround the light emitting element, the light is received by a plurality of light receiving elements. Light can reach the element directly or even with minimal reflection to improve light transmission efficiency.

In the photocoupler shown in FIG. 1, since the light emitting element 1 is provided on the semiconductor substrate 10 on which the light receiving element 2 is formed, the distance between the light emitting element 1 and the light receiving element 2 is reduced. As a result, the light transmission efficiency can be improved, and the size of the entire photocoupler can be reduced because the light emitting element 1 and the light receiving element 2 are not arranged in the horizontal direction.

In the photocoupler shown in FIG. 1, a light emitting element 1 and a plurality of light receiving elements 2 are arranged on the same semiconductor substrate 10, and in the photocoupler shown in FIG. The light emitting element 1 and the plurality of light receiving elements 2a, 2b, 2c, 2d are arranged on the substrate 3, and the light emitting element and the light receiving element are not arranged on separate substrates. Therefore, the wire bonding between the light emitting element and the light receiving element can be completed in one step, and the cost can be reduced by simplifying the manufacturing process.

Although the case where four light receiving elements surround the light emitting element has been described with reference to FIG. 2, the number of light receiving elements is not limited to this. The light receiving element shown in FIGS. 1 and 2 may be a single photodiode or a photodiode array in which a plurality of photodiodes formed on the same semiconductor substrate are electrically connected. And the configuration is not limited.

[0037]

As described above, according to the present invention,
A plurality of light receiving elements are arranged so as to surround the light emitting element, and a conductive layer in contact with the back surface of the light emitting element is provided as an electrode of the light emitting element. Therefore, an inexpensive, high light transmission efficiency, and small-sized photocoupler is provided. be able to.

[0038]

[Brief description of the drawings]

FIG. 1 is a plan view and a cross-sectional view showing a configuration of a first embodiment of the present invention.

FIG. 2 is a plan view and a cross-sectional view showing a configuration of a second embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a configuration of a conventional photocoupler.

FIG. 4 is a cross-sectional view illustrating a configuration of a conventional photocoupler.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light emitting element 2, 2a, 2b, 2c, 2d Light receiving element 3, 6 Insulating substrate 4 Transparent resin 5 Mold resin 10 Semiconductor substrate 11 Insulating layer 12 Conductive layer

Claims (6)

[Claims] 1. A photocoupler in which a light emitting element and a light receiving element are optically coupled, wherein the light emitting element is provided on an insulating layer formed on a semiconductor substrate, and the light receiving element is provided on the semiconductor substrate in plural numbers. A photocoupler formed and arranged so as to surround the periphery of the light emitting element. 2. The light-emitting device according to claim 1, further comprising: a conductive layer between the light-emitting device and the insulating layer, the conductive layer being capable of conducting electricity to the light-emitting device, and the conductive layer serving as an electrode of the light-emitting device.
The photocoupler described. 3. A photocoupler in which a light emitting element and a light receiving element are optically coupled with each other, wherein the light emitting element is provided on an insulating substrate, and the light receiving element is provided on the insulating substrate in a plurality. A photocoupler is provided so as to surround the periphery of the photocoupler. 4. Between the light emitting element and the insulating substrate,
4. The photocoupler according to claim 3, wherein a conductive layer that allows current to flow is provided in the light emitting element, and the conductive layer is used as an electrode of the light emitting element. 5. The photocoupler according to claim 1, wherein the plurality of light receiving elements are electrically connected. 6. The photo-detector according to claim 1, wherein said light receiving element is a photodiode array in which a plurality of photodiodes formed on the same semiconductor substrate are electrically connected. Coupler.