Optical coupling device

1. Field of the Invention

The present invention relates to an optical coupling device having a function of electrically isolating an input side and an output side from each other by converting an electrical signal into an optical signal by means of a light emitting device and converting the optical signal back into the electrical signal by means of a light receiving device.

2. Description of the Related Art

An opposed-type optical coupling device in which a light emitting device and a light receiving device are arranged to oppose each other is known in the art. FIG. 20 illustrates an optical coupling device 2000 having such a structure. The optical coupling device 2000 includes a light emitting device 1 and a light receiving device 2 which are mounted on header sections of respective lead frames 14 . The light emitting device 1 and the light receiving device 2 are wire-bonded to the respective lead frames 14 via gold wire 3 . The light emitting device 1 , the light receiving device 2 and the lead frames 14 are molded together with a light transmissive resin 5 into a rectangular parallelepiped shape. The rectangular parallelepiped structure is further molded in a light blocking resin 16 . Thus, the resulting device has a double-molded structure.

FIG. 21 illustrates a structure of another opposed-type optical coupling device 2100 known in the art. In the optical coupling device 2100 , substantially U-shaped insulative substrates 2106 A and 2106 B are used instead of the lead frames 14 . The light emitting device 1 and the light receiving device 2 are placed respectively in the substantially U-shaped insulative substrate 2106 A on the light emitting side and the substantially U-shaped insulative substrate 2106 B on the light receiving side. The two substantially U-shaped insulative substrates 2106 A and 2106 B are attached together so that the devices 1 and 2 , opposing each other, are optically coupled together. Wiring patterns 2104 A and 2104 B are provided on the insulative substrates 2106 A and 2106 B for the devices 1 and 2 , respectively. In FIG. 21, a line 2104 C running substantially through the center of the optical coupling device 2100 denotes an adhesive with which the insulative substrates 2106 A and 2106 B are attached together.

FIG. 22 illustrates a structure of still another optical coupling device 2200 using insulative substrates. The optical coupling device 2200 includes a substantially U-shaped insulative substrate 2206 A and a plate-like insulative substrate 2206 B. Wiring patterns 2204 A and 2204 B are provided on the substantially U-shaped insulative substrate 2206 A, and a wiring pattern 2204 C is provided on the plate-like insulative substrate 2206 B. The wiring pattern 2204 A extends from an area of the substantially U-shaped insulative substrate 2206 A on which the light emitting device 1 is mounted to the outside of the optical coupling device 2200 , where the wiring pattern 2204 A functions as a soldering section. The wiring pattern 2204 B extends from the bottom of one end of the plate-like insulative substrate 2206 B to the outside of the optical coupling device 2200 , where the wiring pattern 2204 B functions as a soldering section. The wiring pattern 2204 C extends from an area of the plate-like insulative substrate 2206 B where the light receiving device 2 is mounted to the bottom of one side surface of the plate-like insulative substrate 2206 B. The plate-like insulative substrate 2206 B is structurally connected to the wiring patterns 2204 A and 2204 B via solder bumps 2208 A and 2208 B. The solder bump 2208 B electrically connects the wiring pattern 2204 C to the wiring pattern 2204 B.

However, when a lead frame is used in an opposed-type optical coupling device, the following problems arise. The thickness of a lead frame is 0.2 mm at minimum. For the light emitting side and the light receiving side in combination, a total thickness of 0.4 mm is required for the lead section, whereby it is difficult to reduce the overall thickness of the optical coupling device. For example, in the conventional example illustrated in FIG. 20, which employs the double-molded structure, the thickness of the optical coupling device 2000 is currently 2.1 mm at minimum.

Moreover, in the optical coupling device 2000 , an electrical signal is first transferred to the light emitting side lead frame 14 and then to the light emitting device 1 mounted on the header section of the light emitting side lead frame 14 . The electrical signal is converted into an optical signal at the junction plane 1 A of the light emitting device 1 , and then propagated to the light receiving device 2 . The optical signal which has been emitted from the junction plane 1 A of the light emitting device 1 toward a side surface thereof is absorbed by the light transmissive resin 5 , whereby substantially no portion of the optical signal reaches the light receiving device 2 . Moreover, substantially all of the optical signal which has reached the periphery of the light transmissive resin 5 is absorbed by the light blocking resin 16 and thus is not propagated to the light receiving device 2 . Thus, the transmission efficiency is poor in this conventional example.

The conventional example illustrated in FIG. 21, which does not use a lead frame, is quite useful in reducing the overall thickness of the optical coupling device. However, in this structure, it is difficult to solder the wiring patterns 2104 A and 2104 B to the insulative substrates 2106 A and 2106 B, respectively, thereby complicating the production process. Moreover, the devices 1 and 2 are mounted in the substantially U-shaped insulative substrates 2106 A and 2106 B, respectively, which makes the die-bonding or wire-bonding process more difficult.

The conventional example illustrated in FIG. 22 is also quite useful in reducing the overall thickness of the optical coupling device. However, it is necessary to make an electrical connection between the wiring pattern 2204 C of the upper, plate-like insulative substrate 2206 B and the wiring pattern 2204 Bon the lower, substantially U-shaped insulative substrate 2206 A, thereby complicating the production process. Moreover, since the devices are mounted in the lower, substantially U-shaped insulative substrate 2206 A, which makes the die-bonding or wire-bonding process more difficult.

According to one aspect of this invention, there is provided an optical coupling device, including: a light emitting device for converting an electric signal into an optical signal and outputting the optical signal; and a light receiving device for receiving the optical signal output from the light emitting device and converting the optical signal into the electric signal, wherein: the light emitting device has a light emitting surface for outputting the optical signal; the light receiving device has a light receiving surface for receiving the optical signal; and the light emitting device and the light receiving device are arranged so that the light emitting surface and the light receiving surface oppose each other, the optical coupling device further including: a first insulative substrate on which the light emitting device is mounted; and a second insulative substrate on which the light receiving device is mounted, wherein: the first insulative substrate has a first cross section; and the second insulative substrate has a second cross section; and at least one of the first cross section and the second cross section is substantially L-shaped.

In one embodiment of the invention, the first insulative substrate has a wiring pattern connected to the light emitting device; and the wiring pattern includes a soldering terminal section.

In one embodiment of the invention, the light emitting device is connected to the wiring pattern by way of wire bonding.

In one embodiment of the invention, the second insulative substrate has a wiring pattern connected to the light receiving device; and the wiring pattern includes a soldering terminal section.

In one embodiment of the invention, the light receiving device is connected to the wiring pattern by way of wire bonding.

In one embodiment of the invention, the soldering terminal section is provided on an opposite side from a leg of the substantially L-shaped cross section with respect to the light receiving device.

In one embodiment of the invention, the first insulative substrate and the second insulative substrate are molded together with a light blocking resin.

In one embodiment of the invention, the light blocking resin includes an epoxy resin.

In one embodiment of the invention, at least one of the first insulative substrate and the second insulative substrate has a protrusion which is provided along an edge of a device mount surface on which either the light emitting device or the light receiving device is mounted, the protrusion being substantially perpendicular to the device mount surface; and a side surface of the protrusion is in contact with an inner surface of the other insulative substrate.

In one embodiment of the invention, the first insulative substrate has a slope portion for reflecting the optical signal output from the light emitting device toward the light receiving device.

In one embodiment of the invention, the optical signal which has been emitted toward a side surface of the light emitting device is reflected by the slope portion toward the light receiving device.

In one embodiment of the invention, the first insulative substrate has a through hole; the first insulative substrate has a wiring pattern connected to the light emitting device; and the wiring pattern extends from an inner surface of the first insulative substrate via the through hole to an outer surface of the first insulative substrate.

In one embodiment of the invention, the second insulative substrate has a through hole: the second insulative substrate has a wiring pattern connected to the light receiving device; and the wiring pattern extends from an inner surface of the second insulative substrate via the through hole to an outer surface of the second insulative substrate.

In one embodiment of the invention, the optical coupling device further includes a light transmissive resin filled the first insulative substrate and the second insulative substrate.

In one embodiment of the invention, the light transmissive resin includes a silicone resin.

The present invention provides an opposed-type optical coupling device which employs an insulative substrate having a wiring pattern provided by plating, or the like, as a substrate on which a light emitting device and a light receiving device are mounted. In this way, it is possible to eliminate the need to use thick lead frames, thereby significantly reducing the overall thickness of the device. Moreover, the substantially L-shaped cross section of the insulative substrate facilitates the die-bonding or wire-bonding process as compared with the case where a substantially U-shaped insulative substrate as in the prior art.

Moreover, the light emitting device side insulative substrate can be provided with a light emitting side soldering terminal section (electrode), and the light receiving device side insulative substrate can be provided with a light receiving side soldering terminal section (electrode). Therefore, it is possible to eliminate the need to connect the wiring pattern on the upper substrate to the wiring pattern on the lower substrate, as in the prior art, thereby significantly improving the productivity.

The light emitting device side insulative substrate and the light receiving device side insulative substrate can be molded together with a light blocking resin. Particularly, when the junction between the light emitting device and the light receiving device has a complicated configuration, the resin molding improves the productivity. Using an adhesive can further stabilize the product quality.

Furthermore, a protrusion may be provided at the tip of the device mount surface of a substantially L-shaped structure of one insulative substrate, so that the protrusion extends in a direction substantially perpendicular to the device mount surface and that a side surface of the protrusion is in contact with an inner side surface of the other insulative substrate. In this way, it is possible to increase the creepage distance along the boundary between the periphery of the light transmissive resin structure and the inner surface of the insulative substrates, thereby increasing the withstand voltage of the optical coupling device. This is because when a high voltage is applied between the light emitting side and the light receiving side, a discharge, if any, would occur in a location where the withstand voltage is lowest, and such a location (within the optical coupling device itself excluding the ambient space) corresponds to the boundary between the periphery of the light blocking resin structure and the inner surface of the insulative substrates.

The leg (herein, the term “leg” is used to refer to the shorter one of the two linear segments of the substantially L-shaped configuration) of the substantially L-shaped cross section of the lower insulative substrate may be provided opposite from the soldering terminal section with respect to the device. In this way, it is possible to increase the creepage distance along the boundary between the periphery of the light transmissive resin structure and the inner surface of the insulative substrates, thereby increasing the withstand voltage of the optical coupling device.

The light receiving device side insulative substrate may be provided with a slope portion so that the optical signal which has been emitted toward a side surface of the light emitting device is reflected by the slope portion toward the light receiving device. In this way, it is possible to significantly improve the optical transmission efficiency.

Moreover, the insulative substrate may be provided with a through hole so that the wiring pattern can extend from the inner surface of the insulative substrate through the through hole to the outside of the optical coupling device. In this way, it is possible to increase the creepage distance along the boundary between the periphery of the light transmissive resin structure and the inner surface of the insulative substrates, i.e., the distance along such a boundary between the electrically active portion on the light emitting side and the electrically active portion on the light receiving side. Herein, the term “electrically active portion” is used to mean any portion of the light emitting side or the light receiving side which is electrically connected to the terminal of the light emitting side or the light receiving side, respectively. In the present specification, the term “electrically active portion” is used to refer to the wiring pattern itself.

Thus, the invention described herein makes possible the advantages of: (1) providing an optical coupling device capable which can be produced with a reduced thickness and an improved productivity, and in which the optical transmission efficiency can be improved.

These and other advantages of the present invention will become apparent to those skilled in the art upon reading and understanding the following detailed description with reference to the accompanying figures.

FIG. 1 is a cross-sectional view illustrating a structure of an optical coupling device according to Embodiment 1 of the present invention;

FIGS. 2A to 2 H illustrates a method for producing the optical coupling device according to Embodiment 1 of the present invention;

FIG. 3 is a cross-sectional view illustrating a structure of an optical coupling device according to Embodiment 2 of the present invention;

FIG. 4 is a cross-sectional view illustrating a structure of an optical coupling device according to Embodiment 3 of the present invention;

FIG. 5 is a cross-sectional view illustrating a structure of an optical coupling device according to Embodiment 4 of the present invention:

FIG. 6 is a cross-sectional view illustrating a structure of another optical coupling device according to Embodiment 4 of the present invention;

FIG. 7 is a cross-sectional view illustrating a structure of still another optical coupling device according to Embodiment 4 of the present invention;

FIG. 8 is a cross-sectional view illustrating a structure of an optical coupling device according to Embodiment 5 of the present invention;

FIG. 9 is a cross-sectional view illustrating a structure of another optical coupling device according to Embodiment 5 of the present invention;

FIG. 10 is a cross-sectional view illustrating a structure of still another optical coupling device according to Embodiment 5 of the present invention;

FIG. 11 is a cross-sectional view illustrating a structure of still another optical coupling device according to Embodiment 5 of the present invention;

FIG. 12 is a cross-sectional view illustrating a structure of still another optical coupling device according to Embodiment 5 of the present invention;

FIG. 13 is a cross-sectional view illustrating a structure of still another optical coupling device according to Embodiment 5 of the present invention;

FIG. 14 is a cross-sectional view illustrating a structure of an optical coupling device according to Embodiment 6 of the present invention;

FIG. 15 is a cross-sectional view illustrating a structure of another optical coupling device according to Embodiment 6 of the present invention:

FIG. 16 is a cross-sectional view illustrating a structure of still another optical coupling device according to Embodiment 6 of the present invention;

FIG. 17 is a cross-sectional view illustrating a structure of still another optical coupling device according to Embodiment 6 of the present invention:

FIG. 18 is a cross-sectional view illustrating a structure of still another optical coupling device according to Embodiment 6 of the present invention;

FIG. 19 is a cross-sectional view illustrating a structure of still another optical coupling device according to Embodiment 6 of the present invention;

FIG. 20 is a cross-sectional view illustrating a structure of a conventional optical coupling device;

FIG. 21 is a cross-sectional view illustrating a structure of another conventional optical coupling device; and

FIG. 22 is a cross-sectional view illustrating a structure of still another conventional optical coupling device.

Various embodiments of the present invention will now described with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view illustrating the general structure of an opposed-type optical coupling device 100 according to Embodiment 1 of the present invention. The optical coupling device 100 includes insulative substrates 6 A and 6 B each having a substantially L-shaped cross section. A light emitting device 1 and a light receiving device 2 are mounted on the insulative substrates 6 A and 6 B, respectively. The light emitting device 1 and the light receiving device 2 are wire-bonded via a gold wire 3 to respective wiring patterns 4 A and 4 B which are provided by plating, or the like. The insulative substrates 6 A and 6 B are attached together so that the devices 1 and 2 oppose each other. The inner gap between the insulative substrates 6 A and 6 B is filled with a light transmissive resin 5 which may be a silicone resin or an epoxy resin.

The optical coupling device 100 may be produced as follows, for example. First, a light receiving side insulative substrate 206 B including a number of light receiving devices 2 mounted thereon (die-bonding or wire-bonding of the light receiving devices 2 has been completed), as illustrated in the perspective view of FIG. 2A, and a light emitting side insulative substrate 206 A including a number of light emitting devices 1 mounted thereon (die-bonding or wire-bonding of the light emitting devices 1 has been completed), as illustrated in the perspective view of FIG. 2B, are provided. The insulative substrates 206 A and 206 B are attached together as illustrated in the perspective view of FIG. 2 C. The light emitting side insulative substrate 206 A has a hole 201 therein for resin injection at a position in the approximate middle between two adjacent optical coupling devices. A transparent resin is injected into the gap between the insulative substrates 206 A and 206 B through the hole 201 , as illustrated in the cross-sectional view of FIG. 2 D. Then, using a disc-shaped cutter 202 , as illustrated in the perspective view of FIG. 2E, half cuts 203 are made in the obtained structure along the boundary between each pair of adjacent optical coupling devices so as to leave the lower substrate uncut, as illustrated in the cross-sectional view of FIG. 2 F. During the cutting process, the resin injection hole 201 is cut away. Then, the obtained half cuts 203 are filled with a light blocking resin 204 , as illustrated in the cross-sectional view of FIG. 2G, and the light blocking resin 204 is allowed to cure. Then, a disc-shaped cutter is used to sever the obtained structure into individual optical coupling devices, as illustrated in the cross-sectional view of FIG. 2 H. Thus, the optical coupling device 100 is produced.

Since the optical coupling device 100 of the present embodiment which is obtained as described above employs the insulative substrates 6 A and 6 B which are provided with the wiring patterns 4 A and 4 B, respectively, there is no need to use thick lead frames. Thus, it is possible to significantly reduce the overall thickness of the optical coupling device 100 to be about 1.4 mm. Moreover, each of the insulative substrates 6 A and 6 B has a substantially L-shaped cross section, thereby facilitating the process of die-bonding or wire-bonding the light emitting device 1 and the light receiving device 2 . Moreover, each of the insulative substrate 6 A for the light emitting device 1 and the insulative substrate 6 B for the light receiving device 2 can be provided with a soldering terminal section 4 C, thereby eliminating the need to connect the wiring pattern on the upper substrate to the wiring pattern of the lower substrate as in the conventional examples illustrated in FIGS. 21 and 22, thereby facilitating the manufacturing process.

Alternatively, only one of the light emitting device 1 and the light receiving device 2 may have a substantially L-shaped cross section.

FIG. 3 is a cross-sectional view illustrating the general structure of an opposed-type optical coupling device 300 according to Embodiment 2 of the present invention. In FIG. 3, those elements which are also included in the optical coupling device 100 and shown in FIG. 1 are provided with the same reference numerals, and will not be further described below. The optical coupling device 300 has a structure similar to that of the optical coupling device 100 illustrated in FIG. 1 except that slope sections 36 C are provided in a substantially L-shaped insulative substrate 36 A for the light emitting device 1 .

The optical signal which has been emitted from a junction plane 1 A of the light emitting device 1 toward side surfaces of the light emitting device 300 is reflected by the slope sections 36 C toward the light receiving device 2 so as to be received by the light receiving device 2 . Thus, the optical transmission efficiency can be significantly improved.

FIG. 4 is a cross-sectional view illustrating the general structure of an opposed-type optical coupling device 400 according to Embodiment 3 of the present invention. In FIG. 4, those elements which are also included in the optical coupling device 100 and shown in FIG. 1 are provided with the same reference numerals, and will not be further described below. The optical coupling device 400 has a structure similar to that of the optical coupling device 100 illustrated in FIG. 1 except that through holes 46 C and 46 D are provided in the substantially L-shaped insulative substrates 46 A and 46 B, respectively, and that wiring patterns 44 A and 44 B extend respectively from the inner surface of the insulative substrates 46 A and 46 B through the through holes 46 C and 46 D to the outside of the optical coupling device 400 .

In this way, the wiring patterns 44 A and 44 B can be extended along the outer surface of the insulative substrates 46 A and 46 B, respectively. Thus, it is possible to increase the creepage distance along the boundary between the periphery of the light transmissive resin structure 5 and the inner surface of the insulative substrates, i.e., the distance along such a boundary between the electrically active portion on the light emitting side and the electrically active portion on the light receiving side, thereby significantly improving the withstand voltage.

Alternatively, only one of the light emitting device side and the light receiving device side may be provided with such a through hole.

FIG. 5 is a cross-sectional view illustrating the general structure of an opposed-type optical coupling device 500 according to Embodiment 4 of the present invention. In FIG. 5, those elements which are also included in the optical coupling device 100 and shown in FIG. 1 are provided with the same reference numerals, and will not be further described below. The optical coupling device 500 has a structure similar to that of the optical coupling device 100 illustrated in FIG. 1 except that substantially L-shaped insulative substrates 56 A and 56 B on which the light emitting device 1 and the light receiving device 2 are mounted, respectively, are molded together with a light blocking resin 7 such as an epoxy resin.

In this way, the light emitting side and the light receiving side can be attached together without using an adhesive.

As a variation of the present embodiment, FIG. 6 illustrates an optical coupling device 600 in which an insulative substrate 66 A is provided with a slope section 66 C so that the optical signal which has been emitted from the junction plane 1 A of the light emitting device 1 toward side surfaces of the light emitting device 600 can be reflected by the slope section 66 C toward the light receiving device 2 so as to be received by the light receiving device 2 .

As another variation of the present embodiment, FIG. 7 illustrates an optical coupling device 700 in which insulative substrates 76 A and 76 B are provided with through holes 76 C and 76 D, respectively, so that wiring patterns 74 A and 74 B can extend respectively from the inner surface of the insulative substrates 76 A and 76 B through the through holes 76 C and 76 D to the outside of the optical coupling device 700 .

FIG. 8 is a cross-sectional view illustrating the general structure of an opposed-type optical coupling device 800 according to Embodiment 5 of the present invention. In FIG. 8, those elements which are also included in the optical coupling device 100 and shown in FIG. 1 are provided with the same reference numerals, and will not be further described below. The optical coupling device 800 has a structure similar to that of the optical coupling device 100 illustrated in FIG. 1 except that protrusions 86 C and 86 D are provided respectively at the tip of the device mount surfaces of the substantially L-shaped insulative substrates 86 A or 86 B. The protrusions 86 C and 86 D extend in respective directions substantially perpendicular to the device mount surfaces, and each of side surfaces 86 E and 86 F of the protrusions 86 C and 86 D of the insulative substrates 86 A and 86 B, respectively, is in contact with an inner side surface 86 G or 86 H of the other insulative substrate 86 B or 86 A via the wiring pattern 4 B or 4 A, respectively.

In this way, it is possible to increase the creepage distance along the boundary between the periphery of the light transmissive resin structure 5 and the inner surface of the insulative substrates 86 A and 86 B, thereby significantly increasing the withstand voltage of the optical coupling device 800 .

Alternatively, only one of the light emitting device side and the light receiving device side may be provided with such a protrusion.

As variations of the present embodiment, FIGS. 9 and 12 illustrate optical coupling devices 900 and 1200 in which insulative substrates 96 A and 126 A are provided with slope sections 96 B and 126 B, respectively, so that the optical signal which has been emitted from the junction plane 1 A of the light emitting device 1 toward side surfaces of the light emitting devices 900 and 1200 can be reflected by the slope section 96 B and 126 B, respectively, toward the light receiving device 2 so as to be received by the light receiving device 2 .

As further variations of the present embodiment, FIGS. 10 and 13 illustrate optical coupling devices 1000 and 1300 in which insulative substrates 106 A and 106 B, and 136 A and 136 B are provided with through holes 106 C and 106 D, and 136 C and 136 D, respectively, so that wiring patterns 104 A and 104 B, and 134 A and 134 B can extend respectively from the inner surface of the insulative substrates 106 A and 106 B, and 136 A and 136 B through the through holes 106 C and 106 D, and 136 C and 136 D to the outside of the optical coupling devices 1000 and 1300 , respectively.

As still other variations of the present embodiment, FIGS. 11, 12 and 13 respectively illustrate optical coupling devices 1100 , 1200 and 1300 in which substantially L-shaped insulative substrates 86 A and 86 B, 126 A and 126 C, and 136 A and 136 B are respectively molded together with the light blocking resin 7 .

FIG. 14 is a cross-sectional view illustrating the general structure of an opposed-type optical coupling device 1400 according to Embodiment 6 of the present invention. In FIG. 14, those elements which are also included in the optical coupling device 100 and shown in FIG. 1 are provided with the same reference numerals, and will not be further described below. The optical coupling device 1400 has a structure similar to that of the optical coupling device 100 illustrated in FIG. 1 except that a leg 146 D of the substantially L-shaped cross section of a lower insulative substrate 146 B is provided opposite from a soldering terminal section 144 B with respect to the light receiving device 2 .

In this way, it is possible to increase the creepage distance along the boundary between the periphery of the light transmissive resin structure 5 and the inner surface of the insulative substrates 146 A and 146 B, thereby improving the withstand voltage of the optical coupling device 1400 .

As variations of the present embodiment, FIGS. 15 and 18 illustrate optical coupling devices 1500 and 1800 in which insulative substrates 166 A and 186 A are provided with slope sections 166 C and 186 C, respectively, so that the optical signal which has been emitted from the junction plane 1 A of the light emitting device 1 toward side surfaces of the light emitting devices 1500 and 1800 can be reflected by the slope section 166 C and 186 C, respectively, toward the light receiving device 2 so as to be received by the light receiving device 2 .

As further variations of the present embodiment, FIGS. 16 and 19 illustrate optical coupling devices 1600 and 1900 in which insulative substrates 166 A and 196 A are provided with through holes 166 B and 196 B, respectively, so that wiring patterns 164 A and 194 A can extend respectively from the inner surface of the insulative substrates 166 A and 196 A through the through holes 166 B and 196 B to the outside of the optical coupling devices 1600 and 1900 , respectively.

As other variations of the present embodiment, FIGS. 17, 18 and 19 illustrate optical coupling devices 1700 , 1800 and 1900 in which substantially L-shaped insulative substrates 176 A and 146 B, 186 A and 146 B, and 196 A and 146 B are respectively molded together with the light blocking resin 7 .

In Embodiments 1-6 described above, the light emitting device 1 is mounted on the upper insulative substrate while the light receiving device 2 is mounted on the lower insulative substrate. Alternatively, the light emitting device 1 may be mounted on the lower insulative substrate while the light receiving device 2 may be mounted on the upper insulative substrate.

As described above in detail, the present invention employs a substantially L-shaped cross section for an insulative substrate of an optical coupling device. In this way, it is possible to provide a low-cost opposed-type optical coupling device, while significantly reducing the overall thickness of the optical coupling device, facilitating the die-bonding or wire-bonding process, and improving the optical transmission efficiency or the withstand voltage of the optical coupling device.

Various other modifications will be apparent to and can be readily made by those skilled in the art without departing from the scope and spirit of this invention. Accordingly, it is not intended that the scope of the claims appended hereto be limited to the description as set forth herein, but rather that the claims be broadly construed.