JPH08139344A - Optical semiconductor device - Google Patents

Abstract

PURPOSE: To simplify the structure of a resin sealed optical semiconductor device, and improve its resolution in light reception/emission. CONSTITUTION: An optical semiconductor device is formed by sealing an optical semiconductor device 1, such as a light detecting chip and light emitting chip, with transparent resin 4. The face of the sealing resin 4, opposed to the optical semiconductor device 1, is flattened, and a recess 5 the width of which is almost the same as that of the optical semiconductor device, is formed on the flat surface in the position of the optical semiconductor device's optical axis. Light incident upon the tapered face 5a, positioned on the side of the recess 5, is refracted or reflected sideways. Only the light passing through the flat bottom 5b of the recess 5 is received or emitted, which enables the enhancement of resolution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical semiconductor device including a light emitting element and a light receiving element, and more particularly to a semiconductor device which requires a high resolution by limiting a light emitting angle or a light receiving angle of light to a minute angle.

[0002]

2. Description of the Related Art There is a photo interrupter as a conventional optical semiconductor device, and a light-receiving element receives light emitted from a light-emitting element to detect a light-shielding object located between the two elements. Conventionally, this type of optical semiconductor device, for example, in the case of a light receiving element, a light receiving chip supported by a lead or the like and electrically connected is sealed with a sealing resin having a high light transmittance,
It is configured to receive the light incident through the sealing resin. However, in this configuration, all the light projected toward the light receiving surface of the light receiving chip is received by the light receiving chip, so that the light receiving angle, that is, the resolution, depends on the size of the light receiving chip. Since the reduction of the chip area is limited, the resolution is also low.

Therefore, conventionally, as shown in FIG. 7, a device having a higher resolution has been proposed. That is, the light receiving chip 1 is mounted on the mount portion 2a of one lead 2A of the lead frame 2, electrically connected to the other lead 2B by the metal wire 3, and these are sealed by the transparent sealing resin 4. And
The sealing resin 4 is covered with a light-shielding cover 9, and a slit 10 having a fine width is formed in the cover 9 at a position corresponding to the front surface of the light receiving chip 1. Alternatively, it is proposed that a window is opened instead of the slit. In this configuration, since only the light that has passed through the slit 10 and the window is received by the light-receiving chip 1, the resolution is increased by receiving light having a small light-receiving angle as compared with the area of the light-receiving surface of the light-receiving chip 1. Effective above.

From the same point of view, the actual construction of Sho 62-10946
Japanese Unexamined Patent Publication No. 7 discloses a configuration in which a slit is provided in a light-shielding housing that incorporates a light-receiving or light-emitting element, and even if such a configuration is adopted, the resolution can be improved.

[0005]

However, in this structure, since a light-shielding cover has to be formed on the outside of the sealing resin, the structure becomes complicated, and the number of manufacturing steps is increased and the cost is increased. There is. This also means that the structure described in the above publication also forms a light-shielding housing, which makes the structure more complicated than the one integrated with a sealing resin, and requires a large number of manufacturing steps, resulting in high cost. become.

Further, in the conventional optical semiconductor device shown in FIG. 7, since the step of sealing the light receiving chip with the sealing resin and the step of applying the light shielding cover are independent, they are provided on the cover. It is difficult to accurately position the slit to face the light-receiving chip, and when an error occurs at this position, the efficiency of light reception is reduced, and high-sensitivity light reception cannot be performed. Note that such a problem also applies to the light emitting element.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a resin-sealed type optical semiconductor device in which a light-shielding cover is not required and the structure is simplified and the disassembling ability is improved.

[0008]

According to the present invention, in a resin-sealed type optical semiconductor device, a surface of a sealing resin on a side facing an optical semiconductor element sealed in a transparent resin is formed into a flat surface. At the same time, the optical axis position of the optical semiconductor element on this flat surface is provided with a recess having substantially the same width dimension as the optical semiconductor element.

The recess has a flat bottom surface through which the optical axis of the optical semiconductor element passes and both sides thereof are tapered. Alternatively, the recess is formed as a substantially square recess having tapered surfaces in the vertical and horizontal directions with respect to the flat surface. Further, the recess is formed in a hemispherical shape having the center on the optical axis of the optical semiconductor element.

[0010]

Since the light incident on the side of the concave portion is refracted or reflected to the side, only the light on the optical axis of the optical semiconductor element is received or emitted. It is possible to raise it.

[0011]

Next, the present invention will be described with reference to the drawings. 1 is a perspective view of a first embodiment of the present invention, showing an example in which the present invention is applied to a light receiving element. In the figure,
Reference numeral 1 denotes a light receiving chip such as a photodiode, which is fixed in a state where the substrate is electrically connected to a mount portion 2a provided integrally with one lead 2A of a lead frame 2 having a conductive plate processed. In addition, the electrode pad of the light receiving chip 1 is electrically connected to the pair of leads 2B by the metal wire 3. The mount portion 2a including the light-receiving chip 1, the metal wire 3, and the tips of the leads 2A and 2B are integrally sealed with a resin 4 that transmits light.

The outer shape of the sealing resin 4 is formed in a rectangular parallelepiped shape, and in particular, the front surface portion facing the front surface of the light receiving chip 1 is formed flat, and in the region immediately in front of the light receiving chip 1. Forms a groove 5 along the length direction of the lead frame 2. As shown in the sectional structures of FIGS. 2A and 2B, the concave groove 5 has a tapered surface 5a having an angle θ with which the groove width is gradually narrowed from the front surface of the sealing resin 4 toward the light receiving chip. It has on both sides and has a flat bottom surface 5b between these tapered surfaces 5a. In this case, the width of the opening of the concave groove 5 is made substantially equal to the width dimension of the light receiving chip 1, while the bottom surface 5b is formed with a minute width and parallel to the front surface of the light receiving chip 1.

Therefore, in the light receiving element having this structure, as shown in FIG. 2A, the sealing resin 4 is directed toward the light receiving element 1.
In the light incident from the front surface of the above, the light in the region other than the concave groove 5 goes straight as it is, and is not received by the light receiving element 1. Also, of the light incident on the groove 5, the tapered surface 5a
Since the light incident on is refracted outward, the light is not received by the light receiving chip 1. Then, only the light incident on the bottom surface 5b of the concave groove 5 travels straight toward the light receiving chip 1 and is received by the light receiving chip 1. Therefore, only light having a small luminous flux width corresponding to the bottom surface 5b of the concave groove 5 is received, and the optical semiconductor device having a high resolution is configured.

Now, the relationship between the taper angle θ of the tapered surface 5a of the groove 5 and the resolution will be considered. Generally, epoxy resin is used as the sealing resin for this type of optical semiconductor device,
Its refractive index is about 1.55, and the refractive index of the atmosphere is 1. Therefore, if the taper angle θ is set so that sin θ × L = A, the light incident on the tapered surface 5a will receive light. No light is received at 1. Here, L is the length from the light receiving surface of the light receiving chip 1 to the front surface of the sealing resin 4, and A is the width dimension of the light receiving chip 1. Thereby, as described above, the groove 5
It is possible to enhance the decomposition ability by receiving only the light from the bottom surface 5b of the. Actually, the taper angle θ of the concave groove is set according to the refractive index of the resin to be sealed and the size of the light receiving surface of the light receiving chip.

When FIG. 1 is used for a light emitting element,
As shown in FIG. 2B, the light from the light emitting chip 1A is recessed into
If the taper surface 5a of the above is configured to totally reflect, only the light transmitted through the surface 5b of the concave groove 5 is emitted,
It is possible to emit high-resolution light having a small luminous flux. The refractive index of the epoxy resin is about 1.55,
Since the refractive index of the atmosphere is 1, the taper angle θ for causing total reflection is θ ≧ sin ⁻¹ (1 / 1.55) ≈40 °
Becomes Therefore, if θ> 40 °, only the light on the bottom surface of the concave groove can be emitted to enhance the decomposition ability.

FIG. 3 is a perspective view of the second embodiment of the present invention. In this embodiment, a rectangular recess 6 is formed on the front surface of the encapsulating resin at a position facing the light-receiving chip, and each of the recesses 6 is formed as a tapered surface 6a in the vertical and horizontal directions, and the bottom surface 6b of the recess 6 is formed. Only the light receiving chip 1 is formed on a plane parallel to the light receiving chip 1.

In this structure, of the light incident on the front surface of the sealing resin, the light incident on the portions other than the concave portion 6 goes straight through the sealing resin 4 and is received as described in FIG. 2A. The light is not received by the chip 1. Further, even if the light is incident on the concave portion 6, the light incident on the tapered surface 6a is refracted here, so that it is not received by the light receiving chip 1. Therefore, only the light incident on the bottom surface of the concave portion 6 is received by the light receiving chip 1, and the resolution of light reception can be improved. As a result, in this embodiment, the resolution in both the vertical and horizontal directions can be increased.

FIG. 4 is a perspective view of a third embodiment in which the present invention is applied to a light emitting element and a view showing its light emitting path. In this embodiment, a semispherical concave portion 7 whose center is located on the optical axis of the light emitting chip 1A is formed on the front surface of the sealing resin 4 facing the light emitting chip 1A. Therefore, of the light emitted from the light emitting chip 1A, the light emitted along the optical axis connecting the recess 7 and the light emitting element 1A is directly emitted from the bottom surface of the recess 7 to the outside of the sealing resin 4. Light that is not on the optical axis is reflected laterally by the spherical surface of the concave portion 7 and returned to the rear as it is, or is totally reflected by the front surface of the sealing resin 4, so that it is not emitted from the sealing resin 4. . Therefore, in this configuration, only a minute light beam is emitted, and the resolution can be improved.

FIG. 5 is a sectional view of a fourth embodiment of the present invention, which shows an example in which the thickness of the element in the front-rear direction is limited. FIG. 5A shows a case where the present invention is applied to the light emitting element 1A, and FIG. 5B shows a case where the present invention is applied to the light receiving element 1. In this embodiment, a tapered surface corresponding to the tapered surface of the concave groove or the concave portion of the first embodiment or the second embodiment is divided into a plurality of n pieces, and the divided tapered surfaces are arranged on the same plane. Part 8
It is configured as.

Therefore, as shown in FIG. 5A, when the light from the light emitting chip 1A is projected onto the sawtooth portion 8, the light is reflected to the side by the plurality of divided tapered surfaces 8a and is sealed. It is never injected from the stop resin. Then, only the light that passes through the flat surface 8b on the optical axis of the light emitting chip is emitted from the sealing resin.

Further, as shown in FIG. 5B, the light receiving chip 1
The incident light is refracted by the split tapered surface 8a, so that it is not received by the light receiving chip 1, and only the light that passes through the flat surface 8b on the optical axis of the light receiving chip 1 is received. Therefore, the resolution can be increased. Further, in this configuration, by dividing the tapered surface and positioning it on the same surface, the depth of the concave groove or the concave portion can be reduced to 1 / n,
The light emitting element or the light receiving element can be formed thin.

Incidentally, FIG. 6 shows an example in which a photo interrupter is constructed by using the light emitting element and the light receiving element according to the present invention. FIG. 6A is a perspective view thereof, in which the light emitting element 11 and the light receiving element 12 of the second embodiment are arranged so as to face each other and are integrally housed in a housing 13, and the light from the light emitting element 11 is received by the light receiving element 12. Enable to receive light. Then, the light emitting element 11
The light shielding plate 14 is configured to be movable back and forth in a groove defined between the light receiving element 12 and the light receiving element 12. Therefore, when the edge of the light shielding plate 14 blocks the optical axis connecting the light emitting element 11 and the light receiving element 12, the output of the light receiving element 12 is changed, and the edge position of the light shielding plate 14 can be detected.

FIG. 6B is a characteristic diagram of the output of the light receiving element 12 according to the movement of the light shielding plate 14, where A is the characteristic of the present invention and B is the characteristic.
Is a characteristic using a conventional element (which does not have a slit as shown in FIG. 7). As shown in B, in the conventional element, since the width of the light flux is large depending on the size of the light emitting chip or the light receiving chip, the characteristics have a gradual inclination and the detection sensitivity of the position of the light shielding plate is low. On the other hand, in the present invention, it is understood that the characteristics are steeply inclined and the detection sensitivity of the position of the light shielding plate is high because the resolution of the light emitting element and the light receiving element is increased.

[0024]

As described above, according to the present invention, the concave portion having substantially the same width as the optical semiconductor element is provided at the optical axis position of the optical semiconductor element on the front surface of the sealing resin for sealing the optical semiconductor element. The light incident on the side of the recess is refracted or reflected laterally, and only the light on the optical axis of the optical semiconductor element is received or emitted. As a result, it is possible to improve the resolution in light reception or light emission without providing a light-shielding cover and slits, and it is possible to simplify the structure.

Here, the bottom of the optical semiconductor element through which the optical axis of the optical semiconductor element passes is made flat and both sides thereof are formed as tapered surfaces, so that the light on the optical axis goes straight on and the light incident on the tapered surface is Since the light is refracted toward the outside, it is not received and the resolution in the width direction of the recess is improved.

Further, by forming the recess as a substantially square recess having tapered surfaces in the vertical and horizontal directions with respect to the flat surface, the resolution in both the vertical and horizontal directions can be improved.

Similarly, by forming the concave portion in a hemispherical shape having its center on the optical axis of the optical semiconductor element, it is possible to receive only light within a required range centered on the optical axis and to extend along the circumferential direction. The resolution will be improved.

[Brief description of drawings]

FIG. 1 is a perspective view of a first embodiment of the present invention.

FIG. 2 is a diagram showing light paths of a light emitting element and a light receiving element of the first embodiment.

FIG. 3 is a perspective view of a second embodiment of the present invention.

FIG. 4 is a perspective view of a third embodiment of the present invention and a diagram showing a light path of a light emitting device.

FIG. 5 is a cross-sectional view of a fourth embodiment of the present invention and a diagram showing light paths of a light emitting element and a light receiving element thereof.

FIG. 6 is a schematic configuration diagram and an output characteristic diagram of an example in which the present invention is applied to a photo interrupter.

FIG. 7 is a perspective view of an optical semiconductor device having a conventional slit.

[Explanation of symbols]

 1 Light receiving element 1A Light emitting element 2 Lead frame 4 Sealing resin 5 Recessed groove (5a tapered surface, 5b bottom surface) 6 Recessed portion (6a tapered surface, 6b bottom surface) 7 Recessed portion (semispherical surface) 8 Serrated portion (8a split tapered surface) , 8b flat surface)

Claims (5)

[Claims] 1. An optical semiconductor device in which an optical semiconductor element such as a light emitting chip or a light receiving chip is sealed with a light transmissive resin,
The surface of the sealing resin on the side facing the optical semiconductor element is formed into a flat surface, and a recess having substantially the same width dimension as the optical semiconductor element is provided at the optical axis position of the optical semiconductor element on the flat surface. A characteristic optical semiconductor device. 2. The bottom surface of the recess, through which the optical axis of the optical semiconductor element passes, is flat, and both sides thereof are tapered.
Optical semiconductor device. 3. The optical semiconductor device according to claim 2, wherein the concave portion is formed as a concave groove extending in one direction with respect to the flat surface. 4. The optical semiconductor device according to claim 2, wherein the recess is formed as a substantially square recess having tapered surfaces in the vertical and horizontal directions with respect to a flat surface. 5. The optical semiconductor device according to claim 1, wherein the recess is formed in a hemispherical shape having a center on the optical axis of the optical semiconductor element.