JPH11177124A - Photocoupler device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an easily miniaturizable photocoupler device of high optical coupling efficiency, the small fluctuation and excellent withstand voltage. SOLUTION: By mutually inclining and oppositely arranging a light emitting element 11 and a light receiving element 12, light emitted from the surface of the light emitting element is directly made incident on the light receiving element, the optical coupling efficiency is improved and the fluctuation is suppressed. Also, by separately providing encapsulation resin 15 for the respective light emitting element 11 and light receiving element 12, the withstand voltage is improved and further, light is deflected when it comes and goes from/to the encapsulation resin, and light convergence efficiency is improved. Also, by providing a light reflection part on a lead frame for mounting the light emitting element 11 and reflecting the light emitted from the side face of the light emitting element, the optical coupling efficiency is improved further.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a photocoupler device. More specifically, the present invention relates to an optical coupling semiconductor device in which a light emitting element and a light receiving element are sealed with a resin, and has a high optical coupling efficiency, a good withstand voltage, and is easy to miniaturize. .

[0002]

2. Description of the Related Art A photocoupler device is a semiconductor device in which a light emitting element and a light receiving element are optically coupled and a signal can be transmitted between an input circuit and an output circuit while maintaining an insulating state. . The withstand voltage is, for example, 2500 to
It can be as high as 10,000 volts,
Compared to mechanical relays, they have the advantages of extremely high operating speed, no mechanical wear, and high dielectric strength.

FIG. 5 is a schematic sectional view illustrating the internal structure of a conventional photocoupler device. The photocoupler device 100 shown in FIG. 1 has a so-called “reflection type” structure. That is, the photocoupler device 100
It has a light emitting element 110 and a light receiving element 120. The light emitting element 110 is mounted on a die pad portion of the lead frame 130. The light receiving element 120 is mounted on a die pad portion of the lead frame 140. The light emitting element 110 and the light receiving element 120 are made of the encapsulating resin 15
It is molded so as to be entirely covered by 0. The encaps resin 150 has a property of transmitting light emitted from the light emitting element 110, and is made of, for example, “transparent silicon resin”. The periphery of the encaps resin 150 is covered with the light-reflective mold resin 160.

In the photocoupler device 100, light emitted from the light emitting element 110 is reflected at the interface between the encapsulating resin 150 and the light-reflective molding resin 160 as indicated by arrows in FIG. The light enters the light receiving section of the element 120.

FIG. 6 is a schematic cross-sectional view illustrating the internal structure of an improved conventional photocoupler device. In other words, the photocoupler device 200 shown in the figure also includes the light emitting element 210, the light receiving element 220, and the first lead frame 23.
0, second lead frame 240, encaps resin 2
50, and a light-reflective mold resin 260.

Here, a characteristic of the photocoupler device 200 is that the die pad portions of the first lead frame 230 and the second lead frame 240 are inclined. That is, as shown by an arrow in the drawing, the light A emitted from the side surface of the light emitting element 210 can enter the light receiving element 220.

[0007]

However, the conventional semiconductor device as described above has the following problems.

First, in the “reflection type” photocoupler device 100 as shown in FIG.
There has been a problem that the optical coupling efficiency tends to fluctuate. That is, in the photocoupler device 100, the light emitting element 11
0, light-reflective molding resin 1
Only the light reflected at the interface 60 enters the light receiving element 120 and is used. Here, in such a photocoupler device, when it is actually used, it is necessary to solder and mount a lead on a printed board (not shown) or the like. However, in such a mounting process, thermal stress is applied to the photocoupler device, the state of the interface between the encapsulating resin 150 and the light-reflective molding resin 160 changes, and the light reflectance and the reflecting direction change. Sometimes. As a result, there is a problem that the optical coupling efficiency fluctuates and the operation becomes unstable.

On the other hand, in the improved photocoupler device 200 as shown in FIG. 6, there is a problem that the absolute value is not sufficiently high, though the optical coupling efficiency varies little. That is, in the photocoupler device 200,
In order to make the light emitted from the side surface of the light emitting element 210 directly incident on the light receiving element 220 without reflecting the light, the optical coupling efficiency is controlled by the encapsulating resin 250 and the light reflecting mold resin 2.
It does not depend much on the state of the interface with 60. However, light emitted from the side surface of the light emitting element 210
0 is only a part of the light emitted, and the absolute value of the optical coupling efficiency is not high.

The photocoupler device 10 shown in FIG.
0 and the photocoupler device 200 shown in FIG. 6 also have a problem that it is not easy to sufficiently increase the withstand voltage. That is, in any photocoupler device,
The light emitting element and the light receiving element are molded by integral encapsulation resin. Here, the main elements that lower the dielectric strength of the photocoupler device are a primary lead frame (light emitting element side) and a secondary lead frame (light receiving element side).
Is a leak current flowing between
It flows mainly along the interface between the encapsulating resin and the light-reflective molding resin. Therefore, in order to increase the dielectric strength, it is desirable to lengthen the path of the leak current.
That is, it is desirable to increase the distance of the interface of the resin existing between these lead frames. This distance is
Often referred to as "internal creepage distance".

However, since the conventional photocoupler device as illustrated in FIGS. 5 and 6 is a so-called “single mold type” in which the encapsulating resin is integrated, the “internal creepage distance” is not sufficient. It was difficult to design for a long time. As a result, there is a problem that it is difficult to increase the withstand voltage to a level that satisfies some high safety standards.

The present invention has been made in view of the above-mentioned problems. That is, an object of the present invention is to provide a photocoupler device having high optical coupling efficiency, small fluctuations, good dielectric strength and easy downsizing.

[0013]

That is, in the photocoupler device according to the present invention, the die pad portion of each lead frame on which the light emitting element and the light receiving element are mounted is inclined, and the light emitting element and the light receiving element are inclined. By facing and arranged in a state, at least a part of the light emitted from the main surface parallel to the mounting surface of the light emitting element is directly incident on the light receiving element without being reflected, The optical coupling efficiency is improved, the fluctuation of the optical coupling efficiency during the mounting process is suppressed, and the thickness of the photocoupler device can be kept small.

Here, the lead frame of the light emitting element and the lead frame of the light receiving element are constructed such that the respective inner leads are arranged on substantially the same plane, thereby reducing the conventional structure. Without drastic changes
Various effects described above can be obtained.

Further, by sealing the light emitting element and the light receiving element with different encapsulating resins, it is easy to design the internal creepage distance to be long, and the effect that the withstand voltage is remarkably improved is also obtained. be able to.

Further, by refracting the light between the encapsulating resin and the translucent molding resin disposed between the encapsulating resin, the light emitted from the light emitting element is condensed and efficiently transmitted to the light receiving element. The light can be incident, and the optical coupling efficiency can be further improved.

When the refractive index of the encapsulating resin is higher than that of the translucent molding resin, it is advantageous in that the light can be easily collected by forming the encapsulating resin into a convex lens shape.

Further, by providing a light reflecting portion on the lead frame on which the light emitting element is mounted and reflecting light emitted from the side surface of the light emitting element to guide the light to the light receiving element, the optical coupling efficiency is further improved. can do.

[0019]

According to the present invention, the light emitted from the surface of the light emitting element is directly incident on the light receiving element by arranging the light emitting element and the light receiving element so as to be inclined with respect to each other so that the light coupling efficiency is improved. And the fluctuation can be suppressed.

Further, by separately providing the encapsulating resin for each of the light emitting element and the light receiving element, the withstand voltage is improved, and further, light is refracted when light enters and exits the encapsulating resin, thereby improving the light collection efficiency. be able to.

Further, by providing a light reflecting portion on a lead frame on which the light emitting element is mounted to reflect light emitted from the side surface of the light emitting element, the optical coupling efficiency can be further improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view illustrating a schematic configuration of a photocoupler device according to an embodiment of the present invention. That is, the photocoupler device 10 according to the present invention includes the light emitting element 1
1 and a light receiving element 12. The light emitting element 11 is mounted on a die pad 13A of the lead frame 13. The light receiving element 12 is mounted on a die pad portion 14A of the lead frame 14. Further, these lead frames are placed in such a positional relationship that the respective lead portions 13B and 14B are arranged on substantially the same plane.

Here, in the present invention, the die pad portions 13A and 14A of the respective lead frames are bent and tilted in directions opposite to each other with respect to the lead portions 13B and 14B, and the light emitting element 11 and the light receiving element are received. The device 12 is arranged so as to face the device 12 in an inclined state.

The light emitting element 11 and the light receiving element 12 are molded so as to be entirely covered with the encapsulating resin 15. The encapsulating resin 15 has a property of transmitting light emitted from the light emitting element 11, and for example, “transparent silicon resin” or the like can be used as a material thereof. The periphery of the encaps resin 15 is covered with a light-reflective mold resin 16.

In the photocoupler device 10 of the present invention, of the light emitted from the light emitting element 11, a part 11 of the light emitted from the main surface parallel to the mount surface is used.
A can directly enter the light receiving element 12 as indicated by the arrow in FIG. Further, as shown by an arrow 11B in the same figure, the light component 11B reflected at the interface between the encapsulating resin 15 and the light-reflective molding resin 16 also has the light receiving element 1B.
2 can be led. Thus, according to the present invention,
Since not only reflected light but also direct light contributes to optical coupling, optical coupling efficiency is significantly improved. Also, the photocoupler device 1
Even if the reflectance of the interface of the resin changes due to the heating process when soldering the 0 to a printed board (not shown),
Since the optical coupling component of the direct light is unchanged, the fluctuation range of the optical coupling efficiency can be greatly reduced.

Further, according to the present invention, the die pad portions 13A and 14A of the lead frame are inclined with respect to the lead portions 13B and 14B, respectively, but are not bent at right angles. The size can be kept small. If the die pad portions 13A and 14A are bent at a right angle to the lead portion, there arises a problem that the thickness of the photocoupler device increases. On the other hand, according to the present invention, by appropriately tilting the die pad portions 13A and 14A,
The optical coupling efficiency can be effectively improved while suppressing an increase in the thickness dimension of the photocoupler device. This effect can be remarkably obtained especially when the size of the light receiving element is increased in order to improve the optical coupling efficiency. That is, it is possible to increase the size of the light receiving element and to improve the optical coupling efficiency while suppressing an increase in the dimension of the photocoupler device in the thickness direction.

Next, a second photocoupler device according to the present invention will be described.

FIG. 2 is a cross-sectional view illustrating a schematic configuration of a second photocoupler device according to the present invention. That is, the photocoupler device 20 also includes the light emitting element 21 and the light receiving element 22. The light emitting element 21 is mounted on a die pad section 23A of the lead frame 23, and the light receiving element 22 is mounted on a die pad section 24A of the lead frame 24. Further, the die pad portions 23A and 24A of each lead frame are bent in directions facing each other, and are arranged so that the light emitting element 21 and the light receiving element 22 face each other.

Here, the light emitting element 21 is covered with an encap resin 25A, and the light receiving element 22 is covered with another encap resin 25B. Each encapsulating resin is integrally molded with a translucent resin 26, and the periphery thereof is further molded with a light-shielding resin. The light emitted from the main surface of the light emitting element 21 passes through the encapsulating resin 25A and passes through the translucent molding resin 26A.
To the light receiving portion of the light receiving element 22 through the encapsulating resin 25B.

In the photocoupler device 20 of the present invention, the light emitting element and the light receiving element are sealed with independent encapsulating resins, respectively.
The internal creepage distance between the third and secondary side lead frames 24 is determined by the light-transmitting molding resin 26 and the light-shielding molding resin 27.
It is determined by the length of the interface with. That is, in the present invention, the internal creepage distance can be designed to be sufficiently long, so that the leakage current can be effectively reduced and the withstand voltage can be significantly improved. As a result, it is possible to satisfy a high safety standard that has been difficult to achieve with the conventional photocoupler device. FIG. 2 shows an example in which the light emitting element 21 and the light receiving element 22 are molded with independent encapsulating resins, respectively.
The present invention is not limited to this. That is, even when only one of the light emitting element 21 and the light receiving element 22 is molded with the encapsulating resin, the withstand voltage can be similarly improved.

In the photocoupler device 20,
Similar to the photocoupler device 10 described above with reference to FIG.
Part of the light emitted from the main surface parallel to the mounting surface of the light emitting element 21 can be made to directly enter the light receiving element 22. Therefore, the effect that the optical coupling efficiency is remarkably improved and the fluctuation range of the optical coupling efficiency can be reduced can be similarly obtained.

Furthermore, by appropriately inclining the die pad portions 23A and 24A, the effect of effectively improving the optical coupling efficiency while suppressing an increase in the thickness of the photocoupler device can be obtained. Can be.

Further, according to the present invention, it is possible to further improve the optical coupling efficiency by utilizing the refraction of light generated between the encapsulating resins 25A and 25B and the translucent molding resin 26. Hereinafter, this effect will be described with reference to the drawings.

FIG. 3 is a schematic explanatory view illustrating a configuration utilizing light refraction in the present invention. That is, FIGS. 7A and 7B are enlarged explanatory views of the vicinity of the light emitting element and the light receiving element of the photocoupler device of the present invention, respectively. In each case shown in FIG.
The light emitted from 1 is refracted when entering the translucent mold resin 26 from the encap resin 25A, and is refracted again when entering the encap resin 25B. As a result, light emitted from the light emitting element 21 can be collected and efficiently incident on the light receiving section of the light receiving element 22.

FIG. 3A shows an example in which the refractive indexes of the encapsulating resins 25A and 25B are lower than the refractive index of the translucent molding resin 26. In such a case,
The light emitted from the light emitting element can be condensed and made incident on the light receiving element as shown in the figure by using the portion of the encaps resin having a small curvature. Such a shape of the encap resin is formed by potting the encap resins 25A and 25B on the respective lead frames and then turning the encap resin downward so that the encap resin is deformed by its own weight. Can be. The encapsulating resin may be cured by curing after a predetermined shape is obtained.

On the other hand, FIG.
An example in which the refractive indexes of 5A and 25B are higher than the refractive index of the translucent mold resin 26 will be described. In this case, as shown in the figure, the encapsulating resins 25A and 25B are formed in a convex lens shape to condense light, and the optical coupling efficiency can be improved. The shape as shown in FIG. 3B can be easily obtained by potting. That is, when the encapsulating resin 25A, 25B is potted on the lead frame, and then the encapsulating resin is held on the lead frame in the same posture, the encapsulating resin is crushed by its own weight, and the shape shown in the drawing may be obtained. it can. When the predetermined shape is obtained, the encapsulating resin may be cured by curing.

In addition to the examples shown in FIGS. 3A and 3B,
The shape of the encaps resin can be optimized as appropriate. For example, the outer shape of the encaps resin 25A is determined in consideration of the position of the light emitting element 21 housed therein, the light emission angle, the positional relationship with the light receiving element 22, the difference in the refractive index with the light transmitting mold resin, and the like. It can be determined appropriately. The same applies to the shape of the encap resin 25B.

When the refractive index of the encapsulating resin is higher than the refractive index of the translucent molding resin, the light coupling efficiency can be remarkably improved by forming the encapsulating resin into a simple spherical lens shape. it can. Such a shape can be easily obtained. Further, if an aspherical shape is used in consideration of the various factors as described above, it is possible to further improve the optical coupling efficiency.

On the other hand, when the refractive index of the encapsulating resin is lower than the refractive index of the translucent molding resin, the outer shape of the encapsulating resin is formed into a concave lens shape, so that the light can be condensed more efficiently. Coupling efficiency can be improved. For this purpose, for example, after potting the encapsulating resin on the lead frame, a predetermined “lens type” is pressed to obtain an encapsulating resin having a “concave lens” shape.

Next, a third photocoupler device according to the present invention will be described.

FIG. 4 is a sectional view illustrating a schematic configuration of a third photocoupler device according to the present invention. That is, the photocoupler device 30 also includes the light emitting element 31 and the light receiving element 32. The light emitting element 31 is mounted on a die pad section 33A of the lead frame 33, and the light receiving element 32 is mounted on a die pad section 34A of the lead frame 34. The die pad portions 33A and 4A of each lead frame are bent in directions facing each other and are inclined and opposed. Further, the lead frame 33
Light reflecting portion 3 bent at a substantially right angle from lead portion 33B
3C.

The light emitting element 31 and the light receiving element 32 are sealed with encap resins 35A and 35B, respectively, and these encap resins are molded integrally with the translucent molding resin 36. Further, the periphery thereof is molded with a light shielding mold resin 37.

In the photocoupler device 30, the various effects described above with reference to FIGS. 2 and 3 can be similarly obtained. Further, in the photocoupler 30, the light reflection portion 33C is provided on the lead frame 33, and the light emitting element 3C is provided.
The light 31 </ b> C emitted from one side surface can be reflected and guided to the light receiving element 32. As a result, there is an advantage that the optical coupling efficiency can be further improved.

Further, such a light reflecting portion can be similarly provided in the photocoupler device 10 described above with reference to FIG. 1, for example. As a result, light emitted from the side surface of the light emitting element can be reflected and guided to the light receiving element, and the optical coupling efficiency can be further improved.

The embodiment of the invention has been described with reference to specific examples. However, the present invention is not limited to these specific examples. For example, the inclination angle and the position of the die pad of the lead frame are not limited to the illustrated example, and can be optimized as appropriate.

Further, the space between the encapsulating resin 15 and the light-reflective molding resin 16 or the light-transmitting molding resin 2
6, 36 and the light-shielding mold resin 27, 37,
A member that reflects light may be provided.

[0048]

The present invention is embodied in the form described above, and has the following effects.

First, according to the present invention, the light-emitting element and the light-receiving element are arranged to be opposed to each other with the die pad portion of the lead frame inclined, so that not only reflected light but also direct light is involved in optical coupling. As a result, the optical coupling efficiency is significantly improved.

Further, according to the present invention, even if the state of the interface of the resin changes with the step of heating for mounting the photocoupler device, the component of the direct light is unchanged, so that the light coupling efficiency is reduced. The fluctuation width can be reduced.

Further, according to the present invention, since the die pad portion of the lead frame is not bent to a right angle, the thickness of the photocoupler device can be reduced.
That is, according to the present invention, by appropriately inclining the die pad portion, it is possible to effectively improve the optical coupling efficiency while suppressing an increase in the thickness dimension of the photocoupler device. This effect can be remarkably obtained especially when the size of the light receiving element is increased in order to improve the optical coupling efficiency. That is, it is possible to increase the size of the light receiving element and to improve the optical coupling efficiency while suppressing an increase in the dimension of the photocoupler device in the thickness direction.

Further, according to the present invention, since the light emitting element and the light receiving element are molded with independent encapsulating resins, the internal creepage distance can be designed to be sufficiently long, so that the leakage current can be effectively reduced. It is possible to remarkably improve the withstand voltage. As a result, it is possible to satisfy a high safety standard that has been difficult to achieve with the conventional photocoupler device. This effect can be similarly obtained by molding only one of the light emitting element and the light receiving element with an encaps resin.

Further, according to the present invention, the encapsulating resin for sealing the light emitting element and the light receiving element is formed in the shape of a convex lens, thereby improving the optical coupling efficiency. That is, the optical coupling efficiency can be remarkably improved by making the shape of the encapsulating resin into a spherical lens shape. Furthermore, an aspherical lens shape is appropriately determined in consideration of the position of the light emitting element housed therein, the radiation angle of light, the positional relationship with the light receiving element, the difference in the refractive index with the light transmitting mold resin, and the like. Thereby, the optical coupling efficiency can be further improved.

As described above, according to the present invention, it is possible to provide a photocoupler with improved optical coupling efficiency, small fluctuations, good dielectric strength and easy downsizing. The benefits are enormous.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a schematic configuration of a photocoupler device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a schematic configuration of a second photocoupler device according to the present invention.

FIG. 3 is a schematic explanatory view illustrating a configuration utilizing refraction of light in the present invention.

FIG. 4 is a cross-sectional view illustrating a schematic configuration of a third photocoupler device according to the present invention.

FIG. 5 is a schematic sectional view illustrating the internal structure of a conventional photocoupler device.

FIG. 6 is a schematic sectional view illustrating the internal structure of an improved conventional photocoupler device.

[Explanation of symbols]

 10, 20, 30, 100, 200 Photocoupler device 11, 21, 31, 110, 210 Light emitting element 12, 22, 32, 120, 220 Light receiving element 13, 14, 23, 24, 33, 34 Lead frame 15, 25 , 35 Encap resin 16, 27, 37, 160, 260 Mold resin 130, 140, 230, 240 Lead frame

Claims (7)

[Claims] A first lead frame; a light emitting element provided on a mounting surface of a die pad portion of the first lead frame; a second lead frame; and a second lead frame. A light receiving element provided on the mounting surface of the die pad portion; an encapsulating resin provided to cover the light emitting element and the light receiving element; and a sealing provided to cover the encapsulating resin. And a resin, wherein light emitted from the light emitting element is received by the light receiving element, wherein the die pad portion of the first lead frame and the second lead are provided. By arranging the light emitting element and the light receiving element to face each other with the die pad portion of the frame inclined with respect to each other, the light emitted from the main surface of the light emitting element parallel to the mount surface is emitted. That at least some of the light, without being reflected, the photocoupler apparatus characterized by being configured as being directly incident on the light receiving element. 2. An inner lead portion of the first lead frame and an inner lead portion of the second lead frame are arranged on substantially the same plane. The photocoupler device according to claim 1, wherein 3. A first lead frame; a light emitting element provided on a mounting surface of a die pad portion of the first lead frame; a second lead frame; and a second lead frame. A light receiving element provided on the mounting surface of the die pad portion; a first encapsulating resin provided to cover the light emitting element; and a first encapsulating resin provided to cover the light receiving element. A second encapsulating resin configured to be separated from the capping resin, a light-transmitting molding resin provided to cover the first encapsulating resin and the second encapsulating resin, A light-shielding molding resin provided so as to cover the light-transmitting molding resin, wherein the light emitted from the light-emitting element is received by the light-receiving element. The die pad portion of the first lead frame and the die pad portion of the second lead frame are inclined with respect to each other, and the light emitting element and the light receiving element are arranged to face each other, so that the mounting is performed. A photocoupler device, wherein at least a part of light emitted from a main surface of the light emitting element parallel to a plane is configured to directly enter the light receiving element without being reflected. . 4. The encapsulating resin and the translucent molding resin are made of materials having different refractive indexes from each other, and are light emitted from the light emitting element and are directed from the direction toward the light receiving element. At least a part of the light emitted in the deviated direction is transmitted to the interface between the first encapsulating resin and the translucent molding resin and the interface between the translucent molding resin and the second encapping resin. The photocoupler device according to claim 3, wherein the photocoupler device is configured to be refracted at at least one of the interfaces so as to be incident on the light receiving element. 5. The photocoupler device according to claim 3, wherein a light refractive index of the encapsulating resin is higher than a light refractive index of the translucent molding resin. 6. The light reflection device according to claim 1, wherein the first lead frame reflects at least a part of light emitted from a side surface of the light emitting element substantially perpendicular to the mounting surface and makes the light incident on the light receiving element. 2. The device according to claim 1, wherein
6. The photocoupler device according to any one of items 5 to 5. 7. A first lead having a lead portion, a light reflecting portion arranged substantially at right angles to the lead portion, and a die pad portion inclined with respect to the light reflecting portion. A light emitting element provided on a mounting surface of the die pad portion of the first lead frame; a lead portion; and a die pad portion inclined with respect to the lead portion. A second lead frame; a light receiving element provided on a mounting surface of the die pad portion of the second lead frame; and an encapsulating resin provided to cover the light emitting element and the light receiving element. And a sealing resin provided so as to cover the encapsulating resin. A photocoupler device, wherein light emitted from the light emitting element is received by the light receiving element. At least a portion of the light emitted from the main surface of the light emitting element parallel to the mounting surface by the and by the mutually inclined light-receiving element arranged opposite to the,
The light reflecting portion of the first lead frame is configured to directly enter the light receiving element without being reflected, and at least partially emit light emitted from a side surface of the light emitting element substantially perpendicular to the mounting surface. A photocoupler device configured to be reflected by the light source and to enter the light receiving element.