JPH06268246A - Optical coupling device - Google Patents

Abstract

(57) [Abstract] [Purpose] In an optical coupling device, an interface is eliminated at a boundary between different resins to prevent electrical insulation failure and decrease in withstand voltage. In an optical coupling device in which a light emitting element 15 and a light receiving element 12 are laminated in a thickness direction and the light emitting element 15 and the light receiving element 12 are sealed with a thermosetting light shielding resin 24,
A thermosetting light-transmissive resin insulating layer 14 that polymerizes with the light-shielding resin 24 is interposed between the light-emitting surface of the light-emitting element 15 and the light-receiving surface of the light-receiving element 12. .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical coupling device having a light emitting element and a light receiving element.

[0002]

2. Description of the Related Art In a conventional optical coupling device, as shown in FIG. 10, a light emitting element 3 such as an infrared light emitting diode and a light receiving element 4 such as a phototransistor are respectively provided at the tips of individual metal lead frames 1 and 2. Die-bonded with silver paste,
The two elements 3 and 4 are wire-bonded with a bonding wire such as an Au wire, and are arranged so as to be optically coupled to each other.

Both the elements 3 and 4 are primary-molded with a light-transmissive resin 5 such as a silicon resin or an epoxy resin in order to protect the elements and improve the external quantum efficiency of light.
Further, on the outer periphery of the primary mold body, in order to protect the metal lead frames 1 and 2 and to shield the entry of ambient light, a secondary mold is made with a light shielding resin 6 such as an epoxy resin.

In the optical coupling device having such a structure,
Since the distance between the light emitting element 3 and the light receiving element 4 is relatively large, there is a loss of light, which makes it difficult to drive the optical coupling device at a low current.

As a solution to the above-mentioned drawbacks, Japanese Patent Laid-Open No. Sho 5
There is a photo coupler of No. 9-103387. In the photo coupler, as shown in FIG. 11, the light emitting element 3 is stacked on the light receiving element 4, and the elements 3 and 4 are electrically insulated from each other by a transparent insulating layer 7 such as glass. The light transmission efficiency is improved by keeping the distance from the element 4 narrow.

In the photocoupler, the withstand voltage between the elements 3 and 4 can be set by the thickness of the transparent insulating layer 7, and a sufficiently high value can be obtained.

[0007]

However, in the photocoupler, the transparent insulating layer 7 and the sealing resin that covers the light emitting element 3 and the light receiving element 4 are not chemically bonded,
There is an interface between the two. Therefore, the length of the interface D
Is the creepage distance between the light emitting element 3 and the light receiving element 4, which is extremely short. Then, contaminants and moisture from the outside easily enter the interfaces on these creeping surfaces, and ionic conduction occurs due to the contaminants and moisture. This phenomenon causes electrical insulation failure during long-term operation as the creepage distance becomes shorter.

Further, the interface between the transparent insulating layer 7 and the sealing resin may be peeled off due to temperature change or the like. At this time, since the distance between the light receiving element 4 and the light emitting element 3 is short, discharge is likely to occur at the separated interface, and the withstand voltage is extremely reduced. The withstand voltage is essential in an optical coupling device (photocoupler).

Further, although the light emitting element 3 emits light not only from the bottom surface but also from the side surface, if the light emitting element 3, the light receiving element 4 and the transparent insulating layer 7 are sealed as they are with a light shielding resin, the light emitting element 3 The side surface is covered with the light shielding resin, and the light emitted from the side surface is absorbed by the light shielding resin and does not reach the light receiving surface of the light receiving element 4. Therefore, the light emitting element 3
The light emitted from the side surface was wasted.

In view of the above problems, the present invention can improve the efficiency of light transmission between the light emitting element and the light receiving element and increase the withstand voltage, and also has a poor insulation and a temperature change during long-time operation. It is an object of the present invention to provide an optical coupling device capable of preventing peeling due to the above and enabling stable operation.

[0011]

The optical coupling device of the present invention comprises:
An optical coupling device in which a light emitting element and a light receiving element are laminated in a thickness direction and the light emitting element and the light receiving element are sealed with a thermosetting light-shielding resin, wherein a light emitting surface of the light emitting element and a light receiving surface of the light receiving element And a thermosetting light-transmitting resin insulating layer which is polymerized with the light-shielding resin. Further, the present invention is characterized in that a light-shielding resin and a thermosetting light-scattering resin which polymerizes with the light-transmitting resin insulating layer are interposed between the light-emitting element and the light-shielding resin. .

[0012]

According to the above structure, in the optical coupling device according to the first aspect of the present invention, the light emitting surface of the light emitting element and the light receiving surface of the light receiving element are optically coupled via the translucent resin insulating layer. Because
The distance between both elements can be narrowed, and the light transmission efficiency can be improved. Further, since the light-transmitting resin insulating layer and the light-shielding resin that seals the light-emitting element and the light-receiving element undergo a polymerization reaction, the light-transmitting resin insulating layer and the light-shielding material that reduce the creepage distance Since there is no interface between the conductive resins, it is possible to suppress a decrease in withstand voltage due to peeling caused by electrical insulation failure and temperature change after long-term operation. Furthermore, since the withstand voltage between both elements can be set by the thickness of the translucent resin insulating layer, the withstand voltage up to the insulation limit can be stably secured, the setting is easy, and the withstand voltage can be improved.

In the optical coupling device according to the second aspect of the present invention, the emitted light emitted from the light emitting element to the light shielding resin side can be scattered by the light scattering resin and diffused to the light receiving element side. As a result, the light that has been conventionally absorbed by the light shielding resin can be received by the light receiving surface of the light receiving element, and the light transmission efficiency can be further improved. Further, since the light-shielding resin, the light-transmitting resin insulating layer, and the light-scattering resin undergo a polymerization reaction, the light-shielding resin and the light-scattering resin and the light-transmitting resin insulating layer and the light-scattering resin are As described above, it is possible to suppress the electrical breakdown and the decrease in the dielectric strength due to peeling.

[0014]

1 is a diagram showing a first embodiment of the present invention, in which FIG. 1 (a) is a plan view and FIG. 1 (b) is a front sectional view.

In the optical coupling device of this embodiment, as shown in FIG. 1, a light receiving element 12 such as a photodiode and a light receiving element mounting electrode portion 13a are provided in the recess of an insulating case substrate 11 having conductor wiring and a recess on the surface. And die-bonded with silver paste or the like, and further, on the light-receiving surface of the light-receiving element 12, a light-emitting element 15 such as a light-emitting diode via a thermosetting translucent resin insulating layer 14 such as an epoxy resin or a polyimide resin. Is installed.

The translucent resin insulation layer 14 will be described in detail. For example, an epoxy resin containing an acid anhydride type curing agent or an amine type curing agent and a silica filler mixed in a weight ratio of 40 to 60% is used. To do. Moreover, the thickness is 0.1 to 0.2 m.
The thickness is about m, and this thickness can provide electric insulation of several kilovolts.

Here, by increasing or decreasing the thickness of the translucent resin insulating layer 14, it is possible to control the light transmission efficiency between the light emitting and receiving elements. However, the light transmission efficiency is inversely proportional to the electric insulation (thinning reduces the light transmission efficiency but decreases the electric insulation. Conversely, increasing the thickness decreases the light transmission efficiency but increases the electric insulation.)
Therefore, it is necessary to set the thickness in consideration of both. In this embodiment, the withstand voltage up to the insulation limit is secured and the light transmission efficiency is increased.

The light emitting element 15, the light receiving element 12 and the translucent resin insulating layer 14 are adhered to each other by forming adhesive layers 16 and 17 on the front and back surfaces of the translucent resin insulating layer 14, as shown in FIG. A method of fixing the light emitting element 15 on the light receiving element 12 through the translucent resin insulating layer 14 by using the adhesive property is used. For example, as shown in FIG. 3 (a), a thin plate-shaped translucent resin insulating layer 14 is attached to a light emitting element wafer 18 with an adhesive layer 16, and a wafer fixing sheet 19 is attached with an adhesive layer 17. As shown in FIG. 3B, these are multi-divided by dicing and then integrated with the translucent resin insulation layer 14 as shown in FIG.
5 is mounted and fixed on the light receiving surface of the light receiving element. That is, here, the translucent resin insulating layer is interposed between the light emitting element and the light receiving element, and only temporary fixing is performed,
No heat curing step is performed.

As shown in FIG. 1A, after mounting the light emitting element 15 and the light receiving element 12 in the recess of the insulating case 11, the electrode portions 20 and 21 of the light emitting element 15 and the electrode portion 22 of the light receiving element 12 are removed. The electrodes 13b, 13c, 13d provided on the insulating case 11 are electrically connected to each other by the bonding wire 23. Then, Figure 1
As shown in (b), in the concave portion of the insulating case 11, a thermosetting light-shielding resin such as an epoxy resin or a polyimide resin is provided in order to block ambient light to the light receiving element 12 and protect the both elements 12 and 15. 24 is injected. The amount of the light-shielding resin 24 is such that both elements 12, 15 are sufficiently covered. The light-shielding resin 24 will be specifically described. For example, in the visible region to the infrared region, the thickness is 0.15 mm and the transmittance is 10%.
A liquid epoxy resin as shown below is used.

Next, all of them are heated to 100 ° C. to 200 ° C., and the light shielding resin 24 and the light transmitting resin insulating layer 1 are
A curing reaction is caused to occur in each of 4 and further a polymerization reaction is caused to occur at the boundary between the light-shielding resin 24 and the light-transmitting resin insulating layer 14 to form an optical coupling device. The polymerization reaction eliminates the interface between the light-shielding resin 24 and the light-transmitting resin insulating layer 14.

The light-transmitting resin insulating layer 14 and the light-shielding resin 24 are polymerized as described above if they are thermosetting like epoxy resin, polyimide resin, or a combination of epoxy resin and polyimide resin. However, it is preferable to use the same resin (for example, epoxy resin-epoxy resin, polyimide resin-polyimide resin) as the light-transmitting resin insulating layer 14 and the light-shielding resin 15 because the polymerization reaction is easy and reliable. .

According to the optical coupling device having the above structure, the translucent resin insulating layer 14 is interposed between the light emitting element 15 and the light receiving element 12, so that the dielectric strength and the light transmission efficiency between the both elements 15 and 12 can be obtained. To be The dielectric strength and light transmission efficiency obtained there are determined by the thickness of the translucent resin insulating layer 14 mounted.

Further, since the light-shielding resin 24 and the light-transmitting resin insulating layer 14 undergo a polymerization reaction, the interface between the light-shielding resin 24 and the light-transmitting resin insulating layer 14 disappears, and after a long time operation It is possible to prevent lowering of the dielectric strength voltage due to peeling caused by poor electrical insulation and temperature change.

4A and 4B are views showing another embodiment of the present invention. FIG. 4A is a sectional view and FIG. 4B is a perspective view before resin sealing.

In this embodiment, as shown in the drawing, metal lead frames 25a, 25b, 25c and 25d are used instead of the insulating case substrate in the above embodiment, and the light receiving element 12 is provided on the electrode portion 26a of the lead frame 25a. The transparent resin insulating layer 14 and the light emitting element 15 are sequentially laminated. Further, also in this embodiment, similarly to the above embodiment, the light-transmitting resin insulating layer 14 and the light-shielding resin 24 for sealing the light emitting element 15 and the light receiving element 12 are cured and polymerized to cause optical coupling. The device is configured.

The transparent resin insulation layer 14 (for example, epoxy resin, polyimide resin, etc.) and the light-shielding resin 24 (for example, epoxy resin, polyimide resin, etc.) are the same as above if they are both thermosetting. Although the polymerization reaction occurs as described above, it is preferable that the light-transmitting resin insulating layer 14 and the light-shielding resin 24 are the same resin because the polymerization reaction is easy and certain.

The light receiving element 12 and the transparent resin insulating layer 1
4. In the laminating step of the light emitting element 15, the translucent resin insulating layer 14 is interposed between the light receiving element 12 and the light emitting element 15, and only temporary fixing is performed. For example, the light emitting element wafer and the sheet-shaped translucent resin insulating layer 14 are bonded together, and the wafer and the insulating layer are integrated and then diced into chips, and die bonded onto the light receiving region of the light receiving element wafer.
Next, a chip in which the light receiving element 12, the translucent resin insulating layer 14, and the light emitting element 15 are integrated is formed by dicing,
It is mounted on the electrode portion 25a with silver paste or the like.

Further, the electrode portion (not shown) of the light emitting element 15 and the electrode portion (not shown) of the light receiving element 12 are respectively provided with electrode portions 26b, 26c, 25d on the lead frames 25b, 25c, 25d. Electrical connection is made by 26d and the bonding wire 23. Further, for the purpose of blocking external light and protecting both elements 12 and 15, the lead frames 25a, 25b, 25c, and 25d are molded with a light-shielding resin 24 by molding or the like except for a part thereof.

As described above, also in this embodiment, as in the above-described embodiment, the translucent resin insulating layer 14 is interposed between the light emitting element 15 and the light receiving element 12, so that the dielectric breakdown voltage between the elements 15 and 12 and Light transmission efficiency can be obtained, and since the translucent resin insulating layer 14 and the light-shielding resin 24 undergo a polymerization reaction, it is possible to prevent electrical insulation failure and reduction in withstand voltage due to peeling.

5A and 5B are views showing still another embodiment of the present invention, wherein FIG. 5A is a perspective view and FIG. 5B is a front sectional view.

In this embodiment, as shown in the drawing, a printed wiring board 32 made of glass epoxy or the like has conductor wirings 30 on the front surface side and the back surface side and through holes 31 for connecting the front and back conductive wirings on the side surface. , The light receiving element 12, the translucent resin insulating layer 14, and the light emitting element 15 are sequentially stacked, and the resin flow stop frame 33 is provided on the through hole 31 of the printed circuit board 32. In this structure, the insulating layer 14 and the light emitting element 15 are sealed with the light shielding resin 24.

The light-transmitting resin insulating layer 14 (eg, epoxy resin, polyimide resin, etc.) and the light-shielding resin (eg, epoxy resin, polyimide resin, etc.) 24 are the same as described above if they are both thermosetting. Although the polymerization reaction occurs as described above, it is preferable that the light-transmitting resin insulating layer 14 and the light-shielding resin 24 are the same resin because the polymerization reaction is easy and certain.

The manufacturing process of the optical coupling device of this embodiment will be described below with reference to FIGS.

First, front and back conductor wirings and through holes 31 for connecting the front and back conductor wirings are formed on one printed circuit board 32 'for molding a large number of pieces, and the light receiving element mounting conductor portion 30' in the front and back conductor wirings is formed. The light receiving element 12 is die-bonded with silver paste or the like. Then, the light receiving element 1
The light-transmissive resin insulating layer 14 on the light-receiving surface 2 and the light-emitting element 15 on the light-transmissive resin insulating layer 14 are die-bonding adhesives having an epoxy resin as a main component and are light-transmissive. It is fixed using an electrically insulating material. next,
The light receiving element 12, the translucent resin insulating layer 14, the light emitting element 1
5 is sealed with light-shielding resin 24. During the sealing, FIG.
As shown in (a), resin flow stop frame 3 for preventing resin flow
3'with the heat-resistant double-sided tape 34, etc.
Stick on 2 '. Here, the resin flow stop frame 3
3'may be pasted together before mounting the light receiving elements and the like. The resin flow stop frame 33 'is made of, for example, a glass epoxy substrate, has a thickness that is higher than the stacked height of the light receiving element 12, the translucent resin insulating layer 14, and the light emitting element 15, and has a width. And the length is the same as that of the printed circuit board 32 '.
It is formed so as to cover the 2 ′ surface end and the through hole 31. After the resin flow stop frame 33 'is bonded, the liquid light-shielding resin 24 is injected to such an extent as to sufficiently cover the light receiving element 12, the transparent resin insulating layer 14, and the light emitting element 15,
Subsequently, the whole of them is heated to 100 to 200 degrees to cause a curing reaction in each of the light-transmissive resin insulating layer 14 and the light-shielding resin 24, and at the same time, between the light-transmissive resin insulating layer 14 and the light-shielding resin 24. Cause a polymerization reaction.

The light-transmitting resin insulating layer 14 (eg, epoxy resin, polyimide resin, etc.) and the light-shielding resin (eg, epoxy resin, polyimide resin, etc.) 24 are the same as above if they are both thermosetting. Although the polymerization reaction occurs as described above, it is preferable that the light-transmitting resin insulating layer 14 and the light-shielding resin 24 are the same resin because the polymerization reaction is easy and certain.

After the resin is hardened, as shown in FIG. 6B, the through hole portion AA 'of the printed circuit board 32' and the BB 'portion orthogonal to them are cut by a method such as dicing to individually couple them. The device is obtained.

According to the above manufacturing method, it is possible to assemble, for example, several hundreds of optical coupling devices on one printed circuit board 32 'at one time, and the production process can be greatly improved.

The operation and effect of this embodiment are the same as those of the above embodiment, and will not be described.

In the present embodiment, as shown in FIG. 8, the internal circuit portion widths d2 to d4 in the front side conductor wiring 30a of the printed board 32 'are made narrower inward than the input and output terminal pair width d1. Spaces d5 and d6 (0.5 to 1.0 mm) are secured outside the circuit part,
A sufficient insulating material (light-shielding resin) thickness can be secured between the internal circuit and the outside of the optical coupling device.

9A and 9B are views showing a second embodiment of the present invention. FIG. 9A is a perspective view and FIG. 9B is a front sectional view. This embodiment will be described only on the points different from the first embodiment shown in FIG. 1, FIG. 4 or FIG.

As shown in FIG. 9, for example, in the optical coupling device of this embodiment, the light-shielding resin 24 and the light-transmitting resin insulating layer 1 are provided between the light emitting element 15 and the light-shielding resin 24 in the first embodiment.
4 is a structure in which a light-scattering resin 35 that polymerizes with 4 is interposed.

The light-scattering resin 35 is made of, for example, an epoxy resin and contains silica or the like in a weight ratio of 40 to 70%, and has a thickness of 0.15 mm in the visible to infrared region of 3 mm.
It has a transmittance of 0 to 70% and a property of scattering the light of the light emitting element 15, and mainly the light emitted from the side surface of the light emitting element 1 is scattered by the light scattering resin 35 and diffused to the light receiving element 12 side. However, it has a function of leading to the light receiving surface.

The manufacturing method of this embodiment is the same as the first embodiment except that the step of coating the light emitting element 15 with the light scattering resin 35 is added before the step of injecting the light shielding resin.

With the above structure, the light emitted from the light emitting element 15 to the light shielding resin 24 side can be scattered by the light scattering resin 35 and diffused to the light receiving element 12 side. As a result, the light that has been conventionally absorbed by the light-shielding resin can be received by the light-receiving surface of the light-receiving element 12, and the light transmission efficiency can be further improved. This light transmission efficiency can be improved by 20 to 30% as compared with the first embodiment. Also,
Since the light-shielding resin 24, the light-transmitting resin insulating layer 14 and the light-scattering resin 35 undergo a polymerization reaction, the light-shielding resin 24
There is no interface between the light-scattering resin 35 and the light-transmitting resin insulating layer 14 and the light-scattering resin 35.
It is possible to suppress a decrease in withstand voltage due to poor electrical insulation and peeling.

Further, in this embodiment, the surface area of the transparent resin insulating layer 14 is set to 2 to 4 which is smaller than that of the light emitting element 15.
By making the area equivalent to double, the light emitting element 15 can be stably
Can be coated with the light-scattering resin 35. Further, by forming the light-scattering resin 35 into a dome shape, the light-scattering resin 35 can be efficiently reflected to the light-receiving surface side of the light-receiving element 12.

The present invention is not limited to the above embodiment, and it goes without saying that many modifications and changes can be made to the above embodiment within the scope of the present invention.

[0047]

As described above, in the optical coupling device according to claim 1 of the present invention, the translucent resin insulating layer is provided between the light emitting surface of the light emitting element and the light receiving surface of the light receiving element. The distance between the elements is narrowed, the light transmission efficiency is improved, and the withstand voltage is improved. Therefore, high output and low current drive of the optical coupling device are possible. Further, both elements can be downsized, and the cost and speed can be reduced.

Further, since the translucent resin insulation layer and the light-shielding resin are polymerized with each other, the interface between the two resins is eliminated, so that the electrical insulation failure and the reduction of the withstand voltage due to peeling can be prevented. Therefore, a more reliable optical coupling device is provided.

Furthermore, since the light emitting element and the light receiving element are laminated, the mounting area can be reduced, and a smaller and thinner optical coupling device can be provided.

In the optical coupling device according to the second aspect of the present invention, the light emitted from the light emitting element to the light shielding resin side is scattered by the light scattering resin and diffused to the light receiving element side. As a result, light can be received by the light receiving surface of the light receiving element, and the light transmission efficiency is further improved.

Further, since the light-shielding resin, the light-transmitting resin insulation layer and the light-scattering resin undergo a polymerization reaction, there is no interface between the respective resins, and insulation due to electrical insulation failure and peeling is the same as above. A reduction in breakdown voltage can be suppressed, and a highly reliable optical coupling device is provided.

[Brief description of drawings]

FIG. 1 is a view showing a first embodiment of the present invention, (a) is a plan view, and (b) is a front sectional view.

FIG. 2 is a layered configuration diagram of a light emitting / receiving element and a translucent resin insulating layer shown in FIG.

FIG. 3 is a diagram showing a step of adhering the light emitting / receiving element and the translucent resin insulating layer shown in FIG.

4A and 4B are views showing another embodiment of the present invention, in which FIG. 4A is a sectional view and FIG. 4B is a perspective view before resin sealing.

FIG. 5 is a view showing still another embodiment of the present invention,
(A) is a perspective view, (b) is a front sectional view.

6A and 6B are views for explaining a manufacturing process of the embodiment shown in FIG. 5, FIG. 6A is a perspective view showing a resin flow stop frame before being attached, and FIG. It is a top view.

FIG. 7 is likewise an enlarged perspective view of a main part.

FIG. 8 is a diagram for explaining the configuration of another front conductor wiring, (a) is a plan view, and (b) is a partially enlarged view.

FIG. 9 is a view showing a second embodiment of the present invention, (a) is a perspective view and (b) is a front sectional view.

FIG. 10 is a cross-sectional view showing a conventional example.

FIG. 11 is a cross-sectional view showing another conventional example.

[Explanation of symbols]

 12 light receiving element 14 translucent resin insulating layer 15 light emitting element 24 light shielding resin 35 light scattering resin

Claims (2)

[Claims] 1. An optical coupling device in which a light emitting element and a light receiving element are laminated in the thickness direction, and the light emitting element and the light receiving element are sealed with a thermosetting light-shielding resin, and a light emitting surface of the light emitting element is provided. An optical coupling device, characterized in that a thermosetting light-transmitting resin insulating layer that polymerizes with the light-shielding resin is interposed between the light-receiving element and the light-receiving surface. 2. A light-curing resin and a thermosetting light-scattering resin that polymerizes with the light-transmitting resin insulating layer are interposed between the light-emitting element and the light-blocking resin. The optical coupling device according to claim 1.