JP3437363B2 - Optical coupling device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting element and a signal processing circuit section (amplifier circuit, comparator circuit, output circuit, etc.).
The present invention relates to an optical coupling device in which a light receiving element having a light emitting element is disposed to face each other and is optically coupled.

[0002]

2. Description of the Related Art In general, an optical coupling device (for example, a photocoupler) in which a light emitting element and a light receiving element are arranged to face each other and is optically coupled is shown in FIG.
The light emitting element 2 is mounted on the light receiving side lead frame 3 and the light receiving element 4 is mounted on the light receiving side lead frame 3.
And the light-receiving element 4 are opposed to each other so that the optical axes of the light-receiving element 4 and the light-receiving element 4 are aligned with each other. Was manufactured by forming a. The light emitting element 2 and the light receiving element 4 are electrically connected to a lead frame for mounting or connection via a bonding wire 8 such as a gold wire.

As the light receiving element 4, as shown in FIG. 13, a light receiving area 10 which is a photodiode, and a signal processing circuit such as an amplifier circuit, a comparator circuit, an output circuit for processing an electric signal once photoelectrically converted in the light receiving area 10. A type in which the unit 11 and the unit 11 are integrated into a single chip and can be directly connected to a microcomputer is expanding its application. This light receiving element 4 is
A PN junction is formed in the light receiving region 10 using a bipolar process, and the light receiving region 1 is formed on the front side of the semiconductor substrate 12.
0 and the signal processing circuit section 11 are arranged side by side so that the light from the light emitting element 2 is received on the front side of the semiconductor substrate 12.

When this type of light receiving element 4 is applied to the optical coupling device shown in FIG. 12, the light receiving element 4 directly receives the light from the light emitting element 2, and the wiring pattern 13 of the signal processing circuit section 11 is also exposed to the light. Cause noise.

Therefore, in order to reduce noise as much as possible, a dummy light receiving element is used to prevent malfunction by comparing the electric signal from the regular light receiving element 4 with the electric signal from the dummy light receiving element. As shown in FIG. 13, a method of forming a light shielding layer 14 above the signal processing circuit section 11 to shield the wiring pattern 13 is used. In FIG. 13, reference numeral 15 is an insulating layer for protecting the wiring pattern 13.

In particular, recently, high speed and high CMR (Common Mode Re) are used for applications such as network communication.
characteristics are required, and in addition, a noise test is often included in the test items of the equipment, and an optical coupling device having a high CMR is also required.

In order to improve the CMR of the optical coupling device, a method of keeping a sufficient insulation distance between the light emitting element 2 on the primary side and the light receiving element 4 on the secondary side to reduce the stray capacitance between the input and the output. Alternatively, the method of shielding the upper side of the wiring pattern 13 of the signal processing circuit unit 11 as described above is used.

In the prior art, as shown in FIG. 12, the header portions of both the light emitting side and the light receiving side lead frames 1 and 3 are offset and bent to provide an insulation distance L between the light emitting element 2 and the light receiving element 4. Although (the distance between the loop vertices of the bonding wires 8 on the light emitting side and the light receiving side) is secured, there is a structural limitation and the insulation distance L may not be sufficiently maintained. It is electrically insulated against a slow signal (between input and output), but when a voltage that changes abruptly is applied, noise may occur in the output due to the stray capacitance between the input and output. Moreover, even if the offset bending is performed to a structurally allowable distance, the insulation distance L is not stable and the reliability is poor due to the variation in the loop shape of the bonding wires 8 on the light emitting side and the light receiving side. Further, the shield method requires a large number of parts, resulting in an increase in manufacturing cost and an increase in failure rate.

Therefore, the applicant of the present invention has filed the following:
As shown in FIG. 14, as shown in FIG. 9, the light emitting element 2 is mounted on the light emitting side lead frame 1, and the light receiving side lead frame 3 is provided on the side opposite to the side irradiated with the light from the light emitting element 2. The light receiving element 4 similar to the one described above is mounted, and the light receiving side lead frame 3 is provided with a light entrance window 20 for allowing light from the light emitting element 2 to enter the light receiving element 4. An optical coupling device in which the light receiving element 4 is arranged so as to face is proposed.

According to this, since the light from the light emitting element 2 is applied to the light receiving area 10 of the light receiving element 4 from the light entrance window 20 and the signal processing circuit section 11 is shielded by the light receiving side lead frame 3, the dummy light receiving is performed. Even if an element is used or a shield is not provided above the wiring pattern 13 of the signal processing circuit unit 11, it is possible to prevent a problem that the wiring pattern 13 of the signal processing circuit unit 11 is exposed to light and causes noise. In addition, since the light receiving element 4 is mounted on the side of the light receiving side lead frame 3 opposite to the side irradiated with the light from the light emitting element 2, the light receiving element 2 and the light receiving element 4 are compared with the structure of the optical coupling device shown in FIG. The insulation distance L1 from the element 4 can be secured, and the CMR of the optical coupling device can be improved.

[0011]

In the optical coupling device shown in FIG. 14 (hereinafter referred to as a conventional optical coupling device), the light receiving area 10 and the signal processing circuit portion 11 in the light emitting element 2 and the light receiving element 4 are formed. Since the front side of the semiconductor substrate 12 is disposed so as to oppose, if wiring is performed by direct wire bonding to the electrode portion of the wiring pattern 13, the loop of the bonding wire 8 should be formed in a direction approaching the light emitting element 2. Therefore, it becomes difficult to secure a stable insulation distance.

However, in reality, since the signal processing circuit section 11 on the front side of the semiconductor substrate 12 faces the light-receiving side lead frame 3, it is possible to perform wiring by wire bonding directly to the electrode section of the wiring pattern 13. Instead, it is necessary to newly form a bonding pad on the back side of the semiconductor substrate 12 and perform wiring by wire bonding.

Therefore, even if the wire can be directly wire-bonded to the electrode portion of the wiring pattern 13, it is difficult to secure the insulation distance stably, and the actual bonding pad is formed to form the wire. In the structure in which the wiring is performed by bonding, the number of parts is increased and the work is complicated, and the manufacturing cost is increased.

Further, when the signal processing circuit unit 11 faces the light-receiving side lead frame 3 (GND potential), sufficient insulation between the signal processing circuit unit 11 and the light-receiving side lead frame 3 is required. Element 4 and light receiving side lead frame 3
An insulating paste or the like is applied between and to mount the light receiving element 4 on the light receiving side lead frame 3. At this time, if an insulating paste or the like flows out into the light entrance window 20 which is a space, it may be difficult to secure insulation, which may impair the reliability or interfere with the light entrance. Accurate control is required, which complicates the work and increases the manufacturing cost.

In view of the above, the present invention facilitates insulation between the primary side and the secondary side in order to reduce malfunction due to noise generated between the light emitting element on the primary side and the light receiving element on the secondary side. Moreover, it is an object of the present invention to provide an optical coupling device that can be reliably achieved.

[0016]

According to the present invention, a light emitting element and a light receiving element are arranged to face each other, and the light receiving element processes a light receiving area and a signal processing circuit for processing an electric signal from the light receiving area. And a light receiving element, the back side of the semiconductor substrate is arranged so as to face the light emitting element, and light can be received from the back side of the semiconductor substrate. It was done.

Thus, the light from the light emitting element strikes the back side of the semiconductor substrate and is received by the light receiving region. Therefore, even when wiring or the like is performed on the signal processing circuit portion on the front side of the semiconductor substrate by the wire bonding, the loop of the bonding wire is formed in the direction away from the light emitting element, so that insulation between the light emitting element and the light receiving element is isolated. It does not affect the distance.

Another means for solving the problems is that a light emitting element is mounted on a light emitting side lead frame, and a light receiving element is mounted on a side opposite to a side of the light receiving side lead frame to which light from the light emitting element is irradiated. A light entrance window for allowing light from the light emitting element to enter the light receiving element is formed in the lead frame, and the light receiving element is arranged with the back side of the semiconductor substrate corresponding to the light receiving region facing the light entering window. It was done.

As a result, of the light from the light-emitting element that has reached the light-receiving side lead frame, only the light that has passed through the light entrance window hits the back side of the semiconductor substrate corresponding to the light-receiving area of the light-receiving element, and the other light is received. Is blocked by the lead frame on the light receiving side, and light does not enter from the back side of the semiconductor substrate corresponding to the signal processing circuit section. Further, in the light-receiving element, the signal processing circuit portion on the front side of the semiconductor substrate can be easily wired by wire bonding or the like by a normal work, and when the light-receiving element is mounted on the light-receiving side lead frame, a normal die bond or the like is required. It can be easily installed in the process.

Then , a condenser means for condensing the light from the light emitting element and guiding it to the light receiving element is provided on the optical path from the light emitting element to the light receiving element. The condensing means is a condensing lens body arranged in the light entrance window or a lens-shaped translucent resin body for sealing the light emitting element. Thereby, the light from the light emitting element is efficiently condensed on the light receiving element, the directivity of the light from the light emitting element is improved, and the light receiving efficiency is improved.

Another means for solving the problem is that a light emitting element is mounted on one of the front surface and the back surface of a translucent insulating substrate,
A light receiving element is mounted on the other of the front surface and the back surface of the insulating substrate, and the light receiving element is arranged such that the back side of the semiconductor substrate faces the insulating substrate. The insulating substrate is made of glass, and a pattern for shielding the back side of the semiconductor substrate corresponding to the signal processing circuit section of the light receiving element is formed on the insulating substrate.

As a result, insulation can be ensured by the insulating substrate, and the light from the light emitting element reaches the light receiving element using glass as a medium. Transmission efficiency is improved. Further, the pattern of the insulating substrate prevents light from the light emitting element from entering from the back side of the semiconductor substrate corresponding to the signal processing circuit section of the light receiving element.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) A first embodiment of the present invention will be described with reference to FIGS. The members having the same functions as those described in the related art are designated by the same reference numerals. In the optical coupling device which is the photocoupler of the present embodiment, as shown in FIGS. 1 and 2, the light emitting element 2 is mounted on the light emitting side lead frame 1 having the mounting header portion 1a, and the light receiving side having the mounting header portion 3a is mounted. The light receiving element 4 is mounted on the lead frame 3, and the lead frames 1 and 3 are both light emitting elements 2.
And the light receiving element 4 are arranged so as to face each other so that the optical axes thereof match.
That is, the light emitting element 2 and the light receiving element 4 are arranged facing each other in the vertical direction and optically coupled.

The light emitting element 2 is a light emitting diode (LE).
D) is used, and the header portion 1 of the light emitting side lead frame 1 is used.
It is die-bonded to the upper surface side (the side facing the light receiving side lead frame 3) of a using an adhesive such as a silver paste.
Further, the light emitting element 2 is electrically connected to the connection lead frame 30 via the bonding wire 8 such as a gold wire as shown in FIG. The bonding wire 8 has a loop formed in the direction toward the light receiving element 4.

The light receiving element 4 comprises a light receiving area 10 which is a photodiode and a signal processing circuit section 11 such as an amplifier circuit, a comparator circuit and an output circuit which processes an electric signal once photoelectrically converted in the light receiving area 10. A light receiving IC chip similar to the conventional one, which is integrated on the chip, is used, and a light receiving region 10 and a signal processing circuit unit 11 are formed side by side on the front side of a semiconductor substrate (chip) 12. A phototransistor may be applied as the light receiving region.

Further, in the light receiving element 4, the back side (sub side) of the chip 12 is thinned by a method such as polishing or etching so that the chip thickness of usually about 500 μm is thinned to about 10 μm. As a result, the back surface of the chip 12 approaches the PN junction portion of the light receiving region 10, and when the back surface of the chip 12 corresponding to the light receiving region 10 is exposed to light,
Photoelectric conversion is performed in the same manner as when the front side of the chip 12 is exposed to light. That is, by thinning the back side of the chip 12 so that the light hitting the back side of the chip 12 can pass through the inside of the chip 12 and reach the vicinity of the PN junction, the light normally received from the front side of the chip 12 can be removed. The light can be received from the back side. Instead of thinning the back side of the chip 12, a hole may be formed in the back side of the chip 12 corresponding to the light receiving region 10, and the back side of the chip 12 can receive light. It may be considered from the manufacturing stage.

The light receiving element 4 is die-bonded to the upper surface side of the header portion 3a of the light receiving side lead frame 3, that is, the side opposite to the side irradiated with the light from the light emitting element 2 with an adhesive such as silver paste. . A circular hole is formed in the center of the header portion 3a of the light-receiving side lead frame 3 to form a light entrance window 20 for allowing light from the light emitting element 2 to enter the light receiving element 4. The element 4 is arranged such that the back side of the chip 12 corresponding to the light receiving region 10 faces the light incident window 20. The size of the light entrance window 20 is set to be equal to or slightly larger than the area of the light receiving region 10 so that more light hits the back side of the chip 12 corresponding to the light receiving region 10. As a result, only the back side of the chip 12 facing the light entrance window 20 can receive light, and the back side of the chip 12 corresponding to the signal processing circuit section 11 is shielded by the header section 3a of the light receiving side lead frame 3.

Further, in the light receiving element 4, as shown in FIGS. 3 and 4, the electrode portion in the wiring pattern 13 formed on the front side of the chip 12 is provided with the light receiving side lead frame 3 and a plurality of electrodes via the bonding wire 8 such as a gold wire. Connection lead frame 3
1 is electrically connected. A loop is formed in the bonding wire 8 in a direction away from the light emitting element 2. Therefore, the insulation distance L2 between the light emitting element 2 and the light receiving element 4 is equal to the loop apex of the bonding wire 8 on the light emitting side and the light receiving side. It is the distance from the lower surface of the header portion 3a of the side lead frame 3. Therefore, the insulation distance L2 is larger than the insulation distance L in the optical coupling device shown in FIG. 12, and even if the loop shape of the bonding wire 8 varies on the light receiving side, the insulation distance L2 is not affected. The insulation distance L2 can be stably ensured.

Then, the light-emitting element 2 and the light-receiving element 4, and all the lead frames electrically connected to them are all primary-molded with a light-transmissive resin (for example, a light-transmissive epoxy resin) to form a primary molded body 6. Is formed,
Furthermore, the light-shielding resin (for example,
The secondary mold body 7 is formed by secondary molding with a light-shielding epoxy resin.

In the actual manufacturing process, first, the light emitting element 2 is die-bonded to the upper surface side of the header portion 1a of the light emitting side lead frame 1, and the light receiving element 4 is provided only on the back side of the chip 12 corresponding to the light receiving area 10. After positioning so as to face 20 and die-bonding to the upper surface side of the header portion 3a of the light-receiving side lead frame 3, wiring by wire bonding is performed to electrically connect to each lead frame through the bonding wire 8. Then, the light emitting element 2 and the light receiving element 4 are arranged so as to oppose each other so that the optical axes on the back sides of the chips 12 corresponding to the light receiving regions 10 are aligned and optically coupled, and a primary mold using a light-transmissive resin and Secondary molding is performed using a light-shielding resin.

In the optical coupling device having the above structure, the light from the light emitting element 2 passes through the transparent primary mold body 6 and reaches the lower surface side of the header portion 3a of the light receiving side lead frame 3. Of the light reaching the lower surface side of the header portion 3a, only the light that passes through the light incident window 20 strikes the back side of the chip 12 corresponding to the light receiving area 10 of the light receiving element 4, and the other light is received. Is cut off by the signal processing circuit unit 11
Light does not enter from the back side of the chip 12 corresponding to.

As described above, the light receiving element 4 in which the light receiving region 10 and the signal processing circuit section 11 are arranged side by side on the front side of the chip 12
On the side opposite to the side of the light-receiving side lead frame 3 having the light entrance window 20 irradiated with light from the light-emitting element 2 (header portion 3a).
Since the back side of the chip 12 which is mounted on the light receiving side and faces the light receiving window 20 corresponding to the light receiving region 10, the header part 3a of the light receiving side lead frame 3 of the signal processing circuit part 11 is provided. It serves as a shield, and it is not necessary to provide a light-shielding layer or the like above the signal processing circuit section 11.
It is possible to prevent the light from the light from entering the signal processing circuit unit 11.

The insulation distance L2 between the light emitting element 2 on the primary side and the light receiving element 4 on the secondary side is determined by the loop apex of the bonding wire 8 on the light emitting side and the lower surface of the header portion 3a of the lead frame 3 on the light receiving side. Therefore, even if the loop shape of the bonding wire 8 varies, the insulation distance L2 is not affected and the insulation distance L2 can be stably and sufficiently ensured. As a result, malfunctions due to noise generated between the primary side and the secondary side can be reduced, and the CMR can be improved.

Next, when the conventional optical coupling device is compared with the optical coupling device of the present embodiment, in the conventional optical coupling device, the front side of the chip 12 of the light receiving element 4 faces the light receiving side lead frame 3. On the other hand, in the optical coupling device according to the present embodiment, since the back side of the chip 12 of the light receiving element 4 faces the light receiving side lead frame 3, it is possible to perform wiring by wire bonding directly on the front side of the chip 12. Therefore, unlike the conventional optical coupling device, there is no need to newly form a bonding pad to perform wiring by wire bonding on the back side of the chip 12, the number of parts can be reduced, the work is simplified, and the manufacturing cost is reduced. be able to.

Moreover, when the light receiving element 4 is mounted on the light receiving side lead frame 3, insulation between the signal processing circuit portion 11 and the light receiving side lead frame 3 is not required, and the light receiving element 4 is simply mounted by a process such as normal die bonding. In the conventional optical coupling device, there is no problem such as when an insulating paste or the like is applied to insulate the signal processing circuit unit 11 and the light-receiving side lead frame 3 from each other, the work is simplified, and the manufacturing cost is reduced. Can be cheaper.

Further, in the conventional optical coupling device, the light emitting element 2 and the light receiving element 4 are arranged such that the front sides of the chips 12 face each other, whereas in the optical coupling device of this embodiment, the light emitting element 2 and Since the back side of the chip 12 of the light receiving element 4 is arranged so as to face each other, when wiring by wire bonding is performed on the front side of the chip 12, a loop of the bonding wire 8 is formed in a direction away from the light emitting element 2. It Therefore, in the conventional optical coupling device, assuming that wiring by wire bonding is performed on the front side of the chip 12 without considering the existence of the light-receiving side lead frame 3, the loop of the bonding wire 8 approaches the light emitting element 2. However, in the optical coupling device according to the present embodiment, such a problem does not occur, and the insulation distance L2 does not occur.
Can be secured stably.

Further, in the optical coupling device according to the present embodiment, the light receiving element 4 has the chip 12 corresponding to the light receiving region 10.
In order to enable light reception from the back side of the chip 12, the back side of the chip 12 is thin, and a thinner one than the light receiving element 4 in the conventional optical coupling device is used. Therefore,
The optical coupling device can be made thinner than ever before.

(Second Embodiment) In the second embodiment, the light emitting element 2 of the optical coupling device in the first embodiment is used.
A light condensing unit that condenses the light from the light emitting element 2 and guides it to the light receiving element 3 is provided on the optical path from the light receiving element 3 to the light receiving element 3.

As shown in FIG. 5, the condensing means is composed of a condensing lens body 36 (specifically, a convex lens-shaped glass material) fixed in the light entrance window 20 with a transparent silicon resin 35 or the like.
Light from the light emitting element 2 passing through the light incident window 20 is condensed toward the light receiving region 10 of the light receiving element 4. The condenser lens body 36
Is fixed before wiring by wire bonding. Thereby, the light receiving efficiency of the light receiving element 4 can be improved.

Further, as another condensing means, as shown in FIG. 6, a light-transmitting resin body 37 having a convex lens shape for sealing the light emitting element 2 may be used. The translucent resin body 37 is formed by potting a silicon resin on the light emitting element 2. Note that the potting is performed after the wiring by wire bonding is performed, and the shape may be adjusted after the potting. The shape is not limited to the convex lens shape, and may be a concave lens shape or a Fresnel lens shape as long as it has a function of condensing the light from the light emitting element 2. Thus, the translucent resin body 37 plays a role of a lens due to the difference in the refractive index between the materials of the primary mold body 6 and the translucent resin body 37, and the directivity of the light from the light emitting element 2 is improved to improve the light receiving element. The light receiving efficiency of No. 4 can be improved.

In addition to the above, the condensing means is a lens body formed by potting a silicon resin or the like on the light receiving window 20 on the light receiving side, or interposed between the light emitting element 2 and the light receiving window 20. A light guide formed of silicon resin or the like may be used.

(Third Embodiment) In the third embodiment, as shown in FIGS. 7 and 8, the light emitting element 2 is subjected to bump processing on the back surface (lower surface) of the glass insulating substrate 40 with the light emitting surface facing upward. The light receiving element 4 is mounted on the surface (upper surface) of the insulating substrate 40 by die bonding. The light receiving element 4 is
The back side of the chip 12 is arranged to face the insulating substrate 40, and the light emitting element 2 and the back side of the chip 12 of the light receiving element 4 are arranged to face each other via the insulating substrate 40 to receive light from the back side of the chip 12 of the light receiving element 4. It is like this.

The light emitting device 2 is formed on the lower surface of the insulating substrate 40.
Wiring patterns 41 electrically connected to both the anode and cathode electrodes of the chip are formed, and on the upper surface of the insulating substrate 40, the back side of the chip 12 corresponding to the signal processing circuit section 11 of the light receiving element 4 (light receiving region 10 A shield pattern 42 for shielding (excluding a portion corresponding to the) is formed.

Further, the wiring pattern 41 of the insulating substrate 40
The lead frame 43 on the light emitting side is electrically connected to. The wiring pattern 13 on the front side of the chip 12 in the light receiving element 4 is electrically connected to the lead frame 44 on the light receiving side via the bonding wire 8.

Here, the above bump processing will be described. As shown in FIG. 8, the anode of the surface emitting type light emitting element 2
A ball 45 formed by using solder or gold or the like is formed on both electrodes of the cathode, and both the anode and cathode electrodes of the light emitting element 2 are bonded to the wiring pattern 41 of the insulating substrate 40 through the ball 45. This is a method of mounting the light emitting element 2 on the insulating substrate 40 by electrically connecting. When the balls 45 are solder, a gap 41a is provided in the wiring pattern 41 so that the solder does not spread during bonding. This prevents the solder from spreading outward due to the tension of the solder itself when the solder is melted. Also, the ball 45
When the gold is gold, the wiring pattern 41 is made of a conductive paste.
Glue with.

As another method of mounting the wire bondless, as shown in FIG. 9, there is a method of bonding both the anode and cathode electrodes of the edge emitting type light emitting element 2 to the wiring pattern 41 with the solder paste 46. According to this method, the light emitting element 2 can be mounted almost horizontally to the insulating substrate 40. In FIGS. 8 and 9, 47 is an opening through which light from the light emitting element 2 passes.

After the light emitting element 2 and the light receiving element 4 are mounted and electrically connected, molding is performed with a light blocking resin to form a molded body 48. Other configurations are similar to those of the first embodiment.

Thus, the light emitting element 2 and the light receiving element 4
Is mounted directly on the insulating substrate 40, the light emitting element 2
The insulating distance L3 between the light receiving element 4 and the light receiving element 4 is equal to the thickness of the insulating substrate 40, and the bonding wire on the light emitting side that affects the insulating distance L3 can be eliminated. It is possible to secure more stable and sufficient. In addition, since the shield pattern 42 for shielding the back side of the chip 12 corresponding to the signal processing circuit section 11 of the light receiving element 4 is formed on the insulating substrate 40, the light from the light emitting element 2 emits light from the signal processing circuit of the light receiving element 4. It is possible to prevent the portion 11 from entering. As a result, malfunctions due to noise generated between the primary side and the secondary side can be reduced, and the CMR can be improved.

Further, since the light from the light emitting element 2 reaches the light receiving element 4 using glass as a medium, the light transmission efficiency is improved as compared with the case where the light transmissive resin is used as a medium, and the light receiving efficiency of the light receiving element 4 is improved. Can be improved.

Further, the lead frame and the primary molded body having the header portion for mounting the light emitting element 2 and the light receiving element 4 can be eliminated to reduce the manufacturing cost. In addition, there is no lead frame or bonding wire that affects the insulation distance between the light emitting element 2 and the light receiving element 4, and even if the light emitting element 2 and the light receiving element 4 are brought close to each other by the amount of the lead frame or the bonding wire. Since the insulation distance can be secured, the optical coupling device can be thinned.

(Fourth Embodiment) In the fourth embodiment, as shown in FIG. 10, the light receiving element 4 is irradiated with the light from the lower surface side of the header portion 3a of the light receiving side lead frame 3, that is, the light emitting element 2. On the side where the insulating layer 50 is provided. The light receiving element 4 is arranged such that the front side of the chip 12 faces the header portion 3a, and the light emitting element 2 and the light receiving element 4 are arranged.
The chip 12 of the light receiving element 4 is arranged so as to face the back side of the chip 12, and light is received from the back side of the chip 12 of the light receiving element 4.

Further, an opening 51 is formed in a portion of the light-receiving side lead frame 3 where the light-receiving element 4 is mounted so that wiring can be directly performed on the front side of the chip 12 by wire bonding. The signal processing circuit unit 1 of the light receiving element 4
The back side of the chip 12 corresponding to 1 (excluding the portion corresponding to the light receiving region 10) is shielded by the light shielding layer 52. Other configurations are similar to those of the first embodiment.

On the other hand, as shown in FIG. 11, instead of the light-receiving side lead frame 3, an insulating substrate 53 arranged opposite to the light-emitting side lead frame 1 is used, and the light-receiving element 4 is provided on the lower surface side of the insulating substrate 53, that is, from the light-emitting element 2. You may make it mount by the above-mentioned bump process at the side where light is irradiated. Also in this case, in the light receiving element 4, the front side of the chip 12 is the insulating substrate 53.
The light emitting element 2 and the back side of the chip 12 of the light receiving element 4 are arranged so as to face each other, and light is received from the back side of the chip 12 of the light receiving element 4. On the lower surface side of the insulating substrate 53, the wiring pattern 5 to which the electrode portion of the wiring pattern 13 on the front side of the chip 12 is electrically connected.
4 are formed. The back side of the chip 12 corresponding to the signal processing circuit section 11 of the light receiving element 4 (excluding the portion corresponding to the light receiving area 10) is shielded by a light shielding layer 55, and a wiring pattern 54 is arranged (not shown). The insulating substrate 53 penetrates the secondary molded body 7 to be exposed to the outside, or is connected to the lead frame via a bonding wire.

As described above, in the above-described present embodiment, the back side of the chip 12 of the light receiving element 4 is the light receiving side lead frame 3 and the insulating substrate 4 as in the first to third embodiments.
Even if it does not face 0, the light emitting element 2 and the back side of the chip 12 of the light receiving element 4 are arranged so as to face each other, and
As long as it is configured to receive light from the back side of 2, the electrical wiring on the light receiving side does not affect the insulation distance between the light emitting element 2 and the light receiving element 4, and the insulation distance is affected by the assembly accuracy. Instead, it will be possible to secure a stable supply.

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. For example, the light emitting element may be arranged on the upper side and the light receiving element may be arranged on the lower side. Also, in the second embodiment,
The light-transmitting lens-like translucent resin body and the light-receiving side condenser lens body may be combined to further enhance the light-receiving efficiency. Furthermore, in the third embodiment, the insulating substrate may be made of a translucent resin. In this case,
Although the light transmission efficiency may be lower than that of an insulating substrate made of glass, similar effects can be obtained except for this.

[0056]

As is apparent from the above description, according to the present invention, the light emitting element and the back side of the semiconductor substrate of the light receiving element are arranged to face each other, and light can be received from the back side of the semiconductor substrate of the light receiving element. Therefore, even if wiring is performed by wire bonding on the front side of the semiconductor substrate in the light receiving element, the loop of the bonding wire is formed in the direction away from the light emitting element, that is, the electrical wiring on the light receiving side is the connection between the light emitting element and the light receiving element. The insulation distance is not affected, and the insulation distance can be stably ensured at a low cost as compared with the structure of the conventional optical coupling device and without being affected by the assembly accuracy. Therefore, malfunction due to noise generated between the primary side and the secondary side can be reduced, and the CMR can be improved.

[0057] the light receiving element is mounted on the side opposite to the side on which light is irradiated from the light emitting element of the light receiving side lead frame having entrance window, and the back side of the receivable semiconductor substrate corresponding to the light receiving area entrance Since it faces the light window, the lead frame on the light receiving side acts as a shield for the signal processing circuit section of the light receiving element, preventing the light from the light emitting element from entering the signal processing circuit section without providing a separate member. can do.

The insulation distance between the light emitting element on the primary side and the light receiving element on the secondary side is at least the distance between the loop apex of the bonding wire on the light emitting side and the lead frame on the light receiving side. In the above, the insulation distance is not affected even if the loop shape of the bonding wire varies, and the insulation distance can be stably and sufficiently secured. As a result, malfunction caused by noise generated between the primary side and the secondary side can be reduced, and the CMR can be further improved.

Further, in the light receiving element, wiring can be easily performed by wire bonding on the signal processing circuit portion on the front side of the semiconductor substrate, and a new bonding pad is formed like a conventional optical coupling device. Since it is not necessary to perform wire bonding wiring on the back side of the semiconductor substrate, the number of parts can be reduced, the work can be simplified, and the manufacturing cost can be reduced.

Moreover, when the light-receiving element is mounted on the light-receiving side lead frame, insulation between the signal processing circuit section and the light-receiving side lead frame is not required, and the light-receiving element can be easily mounted by a normal die bonding process or the like. In the conventional optical coupling device, there is no problem such as when applying an insulating paste or the like to insulate the signal processing circuit unit and the lead frame on the light receiving side, and high reliability as an optical coupling device can be obtained, and work can be performed. Can be simplified and the manufacturing cost can be reduced.

By the light collecting means , the light from the light emitting element can be efficiently guided to the light receiving element, and the light receiving efficiency of the light receiving element can be improved. Therefore, the response is improved, the performance as the optical coupling device can be improved, and the power consumption can be reduced.

Since [0062] Luminous element and a light receiving element is mounted on the insulating substrate, the insulating distance between the light emitting element and the light receiving element becomes the thickness of the insulating substrate, more stably and sufficiently secure the insulation distance can do. Further, since the insulating distance between the light emitting element and the light receiving element is secured by the insulating substrate, restrictions on electrical wiring in the light emitting element and the light receiving element are reduced, and the design can be freely changed according to the application. It will be possible.

[0063] With insulated substrate made of glass, light from the light emitting element so reaches the light receiving element of the glass as a medium, light transmission efficiency is improved as compared to when the translucent resin with medium The light receiving efficiency of the light receiving element can be improved. In addition, the pattern of the insulating substrate can prevent light from the light emitting element from entering the signal processing circuit section of the light receiving element, and reduce malfunction due to noise generated between the primary side and the secondary side. The CMR can be improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an optical coupling device according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of an essential part of an optical coupling device.

FIG. 3 is an internal plan view of the optical coupling device.

FIG. 4 is a plan view of the element mounting portion of the lead frame.

FIG. 5 is a vertical sectional view of an essential part of an optical coupling device according to a second embodiment.

FIG. 6 is a longitudinal sectional view of the main part of another optical coupling device of the same.

FIG. 7 is a vertical sectional view of an optical coupling device according to a third embodiment.

FIG. 8 is a longitudinal sectional view of an essential part of an optical coupling device in which light emitting elements are mounted by a pumping process.

FIG. 9 is a vertical cross-sectional view of a main part of an optical coupling device in which a light emitting element is mounted by another wire bondless mounting method.

FIG. 10 is a longitudinal sectional view of an essential part of an optical coupling device according to a fourth embodiment.

FIG. 11 is a longitudinal sectional view of the main part of another optical coupling device.

FIG. 12 is a vertical cross-sectional view of a general optical coupling device.

FIG. 13 is a vertical sectional view of a light receiving element.

FIG. 14 is a vertical sectional view of a conventional optical coupling device.

[Explanation of symbols]

1 Light emitting side lead frame 2 light emitting element 3 Light receiving side lead frame 4 Light receiving element 10 Light receiving area 11 Signal processing circuit section 12 Semiconductor substrate 20 incident light window 36 Condensing lens body 37 Translucent resin body 40 insulating substrate 42 patterns

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References Japanese Patent Laid-Open No. 2-90576 (JP, A) Japanese Patent Laid-Open No. 3-185880 (JP, A) Actually open 61-207049 (JP, U) Actually open 64- 44655 (JP, U) Actual opening 51-69572 (JP, U) Actual opening 60-146357 (JP, U) Actual opening 50-94873 (JP, U) Actual opening Flat 5-82059 (JP, U) (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01L 31/12

Claims (5)

(57) [Claims] 1. A light emitting element mounted on a light emitting side lead frame and a light receiving element mounted on a light receiving side lead frame are arranged to face each other, and the light receiving element processes a light receiving region and an electric signal from the light receiving region. In an optical coupling device in which a signal processing circuit section is arranged side by side on the front side of a semiconductor substrate , the semiconductor substrate has a back side on a side opposite to a side irradiated with light from the light emitting element of the light receiving side lead frame. I'll face you
Is mounted on the light-receiving side lead frame, a light-entering window for allowing light from the light-emitting element to enter the light-receiving region is formed in the light-receiving side lead frame, and the signal processing circuit unit is connected to the light-receiving side by a wire. An optical coupling device, which is electrically connected directly to the opposite side of the lead frame. 2. An optical path from the light emitting element to the light receiving element,
Optical coupling device according to claim 1, wherein the condensing means condenses the light from the light emitting element guided to the light receiving element is provided. 3. A light emitting element and a light receiving element are arranged to face each other,
The light receiving element, the optical coupling device and the signal processing circuit section for processing the electrical signals from the light receiving region and the light receiving region is formed by juxtaposed on the front side of the semiconductor substrate, the light receiving element is mounted on the insulation substrate the back side of the semiconductor substrate is opposed to the light emitting element, the light of the front side of the semiconductor substrate from the light emitting element of the insulating substrate is disposed facing the side to be irradiated, prior to
A wiring pattern is formed on the side of the insulating substrate that is illuminated by light.
The signal processing circuit section is electrically connected to the wiring pattern, and the back side of the semiconductor substrate corresponding to the signal processing circuit section is shielded from light. 4. A light emitting element is mounted on one of a front surface and a back surface of a translucent insulating substrate, and a light receiving element is mounted on the other of the front surface and the back surface of the insulating substrate. A light-receiving region and a signal processing circuit section for processing an electric signal from the light-receiving region are arranged in parallel on the front side of the semiconductor substrate,
The light receiving element is arranged such that the back side of the semiconductor substrate faces the insulating substrate, and the signal processing circuit unit includes the insulating substrate.
To the lead frame on the receiving side, which is located away from
Ri optical coupling apparatus characterized in that it is electrically connected. 5. The insulating substrate is made of glass, according to claim 4, wherein the pattern for shielding the backside of the semiconductor substrate corresponding to the signal processing circuit section of the light receiving elements in the insulating substrate is formed Optical coupling device.