JPS62143485A - Photocoupler - Google Patents

Abstract

PURPOSE:To improve dielectric strength, optical transmission efficiency and common mode signal rejection ratio, by molding the light-receiving side of a light receiving element with a first transparent resin, and molding the light- emitting side of a luminous element with a second flexible resin of high transparency, the two elements of which are arranged on the same plane. CONSTITUTION:Each of a luminous element 2 and a light receiving element 3 is fixed to a lead-frame 1, 1' and arranged on the same plane. As to resin to be filled in the light transmission part between the luminous element 2 and the light receiving element 3, a first transparent resin 10 and a second flexible resin 11 of high transparency are used for a light-receiving side and a light- emitting side respectively, to form a light waveguide. The outer periphery of the light transmission part formed with the above both resins is molded with the same kind of a light-shielding resin as said first transparent resin 10. Common mode signal rejection ratio, optical transmission efficiency and, further, dielectric strength are improved, thereby.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an optical coupling device in which a light emitting device and a light receiving device are optically coupled and electrically insulated.゛In recent years, photocoupler devices (generally called photocouplers), which connect a light emitting diode and a photodetector such as a phototransistor with an optical path and electrically insulate them, have become popular in sequencers.
, has come to be widely used as an elemental electronic component of solid-state φ relays.

<Summary of the Invention> The present invention provides a light-emitting element and a light-receiving element mounted on a lead frame in order to improve the absolute R# required for an optical coupling element, optical transmission efficiency, and common-mode signal rejection ratio. are arranged side by side in one plane, one light-receiving side of the lead frame is molded with a first light-transmitting resin, and the other light-emitting side is molded with the light-emitting side and an end of the light-receiving side molding 1 facing the other side. is molded with a flexible second highly translucent resin so that the first and second parts are bonded together. The outer periphery of the light transmission section made of the second resin is molded with the same kind of light-shielding resin as the first light-transmitting resin.

<Prior Art> FIGS. 7 to 9 are structural sectional views of different conventional examples of optical coupling elements.

In the optical coupling element shown in FIG. 7, the light transmitting parts of the leads 1 and 1' are connected with a transparent silicone resin 5 by screws and f-rings, and the outer periphery is covered with a light-shielding resin 6.
The exterior was formed by molding.

Further, in the optical coupling device shown in FIG. 8, the light emitting device 2 and the light receiving device 3 bonded to the leads 1.1' are wired with gold wires 4.4, respectively, in the same manner as described above. The light transmission part between the pixel elements 2 and 3 is once transfer-molded with a translucent Ebiki resin 7 mixed with fillers such as fused silica and glass fiber, and then the outer periphery is thoroughly mixed with the same filler. , and transfer molded with a light-shielding Ebixi resin 8 to which a colorant has been added.

The optical coupling element shown in FIG. 9 has a light emitting element 2 and a light receiving element 3 bonded to leads 1 and 1', respectively, arranged in parallel in one plane, and transmits light between the pixel elements 2 and 3. The portion is molded with silicone resin 5, and the outer periphery is further molded with light-shielding Ebixi resin 9.

In the examples shown in FIGS. 7 and 9, a method is often used in which the exterior molding resin 6.9 is made of a material with high light reflectance to increase the light transmission efficiency.

<Problems to be Solved by the Invention> The following three points are particularly important in terms of the performance of the optical coupling device, and they largely depend on the package structure.

The first is the dielectric strength between the primary and secondary, which requires extremely high reliability because the optical coupling device is used as an isolator. The second is 1 as an electrical signal.
This is the transmission efficiency between the second order and the second order, and is desired to be high in terms of circuit design. Although the transmission efficiency depends on the performance of the light-emitting element and the light-receiving element such as a phototransistor, it is important that the resin filled between the primary and secondary parts has a high light transmission efficiency. Third knowledge,
Unlike the dedicated signal from the primary side, the noise that enters the signal input in the same phase is transmitted to the secondary side as an electromagnetic wave and generates an electrical signal in the light receiving element on the secondary side (so-called in-phase signal). The question is whether it can be removed.

Among the conventional structures shown in FIGS. 7 to 9, the structure shown in FIG. 8 is the best in terms of dielectric strength between input and output. In other words, dielectric breakdown occurs at the resin interface, but with a double mold structure using the same type of engineered trousers resin 7.8, the adhesion between the resins is good, making it difficult for interfaces to occur inside the package, resulting in a high dielectric strength voltage. is obtained. However, it is essential to make the thermal expansion coefficient of the internal mold resin 7, which serves as the optical path, similar to that of the external mold resin 8 in order to ensure the reliability of the package and the dielectric strength. It is necessary to contain a filler, which may reduce light transmittance. In order to improve the transmission efficiency of optical signals, it is preferable to use a silicone-based transparent resin 5 as the internal resin, as shown in FIGS. 7 and 9. However, this element structure has a drawback in that the distance between the lines at the boundary between the transparent resin 5 and the light-shielding resin 6 is small, and therefore a large dielectric strength voltage cannot be obtained.

Regarding the common-mode signal ratio, it is necessary that the capacitance between the primary and secondary components be small, and the structure shown in FIG. ing.

The present invention has been made in view of these circumstances, and solves the above problems and improves dielectric strength.

The object of the present invention is to provide a structure of an optical coupling element that can improve optical transmission efficiency and common-mode signal rejection ratio.

Means for Solving Problems> FIG. 1 is a cross-sectional view showing the structure of an optical coupling device according to the present invention, in which a light emitting device 2 and a light receiving device 3 ft are each bonded to a lead frame 1.1', The structures are arranged side by side on the same plane. In addition, the resin filled in the light transmission part between the light receiving and emitting elements 2.3 is filled with a first transparent resin 1 on the light receiving side.
0. A flexible second highly transparent resin 11 is used on the light emitting side to form an optical path, and the outer periphery of the light transmission section made of both resins is made of the same type as the first transparent resin 10. Light-shielding resin 1
2, the package structure was molded.

Effects> As described above, the present invention has a structure in which the light emitting element 2 and the light receiving element 3 are arranged side by side on the same plane, thereby increasing the common mode signal rejection ratio.
A highly translucent resin 11 is filled on the light emitting side of the part that becomes the optical path to improve light transmission efficiency, and the light receiving side is filled with a translucent resin 10 of the same type as the exterior resin to ensure close contact with the exterior mold resin 12. This improves the dielectric strength as well.

<Example:> An example of the optical coupling device according to the present invention will be described in detail based on FIGS. 1 to 5.

FIG. 4 is a cross-sectional structural diagram of an embodiment of the optical coupling device according to the present invention, and FIGS. 2 to 5 are perspective views showing an example of an assembly process for the embodiment of the present invention.

In FIG. 2, a light-emitting element 2 and a light-receiving element 3 are each bonded to one lead part forming the wide part of the lead frame 1, 1', and the upper surface side electrode of each element 2.3 and the element 2.3 are bonded. There is a gold wire 4 between the other lead parts that are not placed.
．． 4 and electrically connected by b.

One of the lead frames 1' is molded with a first translucent resin lO made of epoxy resin or the like so as to cover the light receiving element 3 and the tips of each lead portion, as shown in FIG. The resin 10 for molding the light-receiving element 3 is an epoxy resin similar to the exterior molding resin described later, contains an appropriate amount of filler, and has a coefficient of thermal expansion similar to that of the exterior molding resin. After the primary molding, deburring is performed 3 Next, as shown in FIG. The light emitting element 2 and the light receiving element 3 are arranged in parallel in one plane, and a gel-like or rubber-like silicone is used so that the light emitting element 2 is included and the light emitting element 2 and the light receiving element mold part are combined. A light transmitting portion is formed by molding with a second highly transparent resin 11 such as a transparent resin. After curing this highly translucent resin 11, these resins 10.
The outer periphery of the light transmission section 11 is molded with a light-shielding resin 12.

After going through processes such as lead plating and lead forming, it is completed in the shape shown in Figure 6.

The exterior mold may vary depending on the shape of the product and process considerations.
The shape may include a plurality of light emitting/light receiving elements.

When the resin hardens after the exterior molding F, the first translucent resin 10
The parts that come in contact with each other use the same type of epoxy resin, so they cure together to some extent, resulting in excellent adhesion, without creating an interface between the primary and secondary parts within the package. , is extremely effective in ensuring dielectric strength.

Furthermore, by making the exterior molding resin 12 contain a dispersant having a high light reflectance, it is possible to increase the light transmission efficiency due to the reflection of the light emitted by the light emitting element 2.

It should be noted that with the above structure, it is possible to mold the light-emitting side with a transparent epoxy resin and the light-receiving side with a silicone-based transparent resin to couple the light, but it is generally used as the light-emitting element 2. Crystals such as GaAs are prone to crystal defects due to external stress, which causes deterioration of optical output, so it is preferable that this type of light emitting element 2 is coated with a flexible resin. As shown in this example, it is more appropriate to mold the light-receiving side and then mold the light-emitting side with silicone-based transparent resin.

The present invention can be similarly applied to various types of optical junction devices having different internal connections in addition to those shown in the above embodiments.

Furthermore, forming a part 10' of the first translucent resin 1o covering the light-receiving element 2 with a spherical or elliptical proximate surface (as shown in FIG. 1) is effective in improving the light transmission rate. .

<Effects of the Invention> As described above, according to the present invention, with a simple configuration,
It is possible to provide an optical coupling element that has a high breakdown voltage, a high common-mode signal rejection ratio, and a high transmission efficiency.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional structural diagram of an embodiment of the optical coupling device according to the present invention, FIGS. 2 to 6 are perspective views showing an example of the assembly process for the embodiment of the present invention, and FIGS. 7 to 9 are FIG. 3 is a cross-sectional structural diagram of different conventional examples. 1.1': lead frame, 2: light emitting element, 3: light receiving element, 4, 4: gold wire, 10: first transparent fat, 11: second highly transparent dressing, 12: Light-shielding resin. Agent Patent attorney Aihiko Fuku (and 2 others) Figure 1 Figure 2

Claims (1)

[Claims] 1. In an optical coupling device in which a light emitting element and a light receiving element pair mounted on a lead frame are resin-molded, each lead frame on which the light emitting element and the light receiving element are mounted is placed on the same plane. one light-receiving side is molded with a first light-transmitting resin, and the other light-emitting side is a flexible first molded part so that the light-emitting side and the opposite end of the light-receiving side mold part are connected to each other. 2 with highly translucent resin, and further molded with the first and second resins.
An optical coupling element having a structure in which an outer periphery of a light transmitting part made of resin is molded with a light-shielding resin of the same type as the first light-transmitting resin. 2. The optical coupling device according to claim 1, wherein the first light-transmitting resin contains a filler. 3. The optical coupling device according to claim 1, wherein the flexible second light-transmitting resin is a silicone-based transparent resin. 4. The optical coupling device according to claim 1, wherein the light-shielding resin is made of a resin mixed with a light-reflecting filler. 5. The optical coupling device according to claim 1, wherein a portion of the light-receiving device mold portion is formed in a spherical or elliptical shape.