JPH05190890A - Optically coupled device - Google Patents

Abstract

PURPOSE:To reduce thickness and generation of failure due to release and crack of a mold resin by forming a through hole between recessed parts which are provided on both front and rear surfaces of a heat-resistant insulating resin substrate, then providing a solid plated electrode part on the heat-resistant insulating resin substrate, mounting a light-emitting element and a photodetector on it and molding the recessed parts with resin. CONSTITUTION:A plurality of heat-resistant insulating resin substrates 11 are subjected to injected molding in one piece as one large substrate and at the same time recessed parts 12 and 13 and a through hole 31 are formed. Then, solid plating is performed selectively on the recessed parts 12 and 13 and the front and rear surfaces of the heat-resistant insulation resin substrate 11, thus forming electrode parts 16 and 17. Also, the electrode parts 16 and 17 of the recessed parts 12 and 13 are die-bonded by a connection means 27 of a light-emitting element 14 and a photodetector 15. Then, for protecting these, a liquid translucent resin 28 is poured from the spacing between the element 14 and the photodetector 15 and the substrate 11 into a through hole 31 before curing and further a glare-protection resin 29 is filled to the upper-layer part, thus screening a disturbance light. After that, one large heat-resistant insulation resin substrate 11 is cut in nearly rectangular parallelepiped shape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical coupling device, and more particularly to a surface mounting type optical coupling device having a frameless structure in which wiring is provided on a heat resistant resin substrate by metal plating or the like.

[0002]

2. Description of the Related Art FIG. 3 shows a sectional view of a conventional optical coupling device (photocoupler). As shown in FIG. 3, a metal lead frame 1, which is made of various metals such as Cu and Ni, and is plated with Sn.
At the tip of 2, the light emitting element 3 (LED chip) and the light receiving element 4
(Photodiode chips and phototransistor chips) are die-bonded to each other and wire-bonded with Au, Al wires or the like, and then arranged so as to face each other. Further, in order to protect both elements 3 and 4 and improve the optical external quantum efficiency, the periphery of these elements is primarily molded with a light-transmissive resin 5 such as an epoxy resin or a thermoplastic resin, and then the metal lead frames 1 and 2 are molded. For protection and shielding of ambient light, a secondary molding was performed with a shielding resin 6 such as an epoxy resin or a thermoplastic resin.

[0003]

In the structure of the conventional optical coupling device, since the metal lead frames 1 and 2 are exposed to the outside, deformation such as bending is likely to occur due to external force,
When the light emitting and receiving elements 3 and 4 are arranged to face each other, the positioning is often inaccurate. In this case, if the two elements 3 and 4 are too close to each other, it becomes difficult to secure electrical insulation between them,
On the contrary, if it is too far away, there is a problem that the light use efficiency is lowered.

Further, when the externally exposed portions of the metal lead frames 1 and 2 are deformed, a positioning error is likely to occur during mounting, which causes a problem.

Further, due to the stress due to the difference in thermal expansion coefficient between the metal lead frames 1 and 2 and the molding resin material of the light-transmitting resin 5 and the light-shielding resin 6, the metal lead frames 1 and 2 and the molding resin are separated from each other. It may be peeled off or cracks may be generated in the molding resin. Then, moisture is likely to enter from the peeled portion or the crack, and electrical short defects or corrosion of the metal wirings of the metal lead frames 1 and 2 and open defects due to wire breakage are likely to occur.

Further, at the present time when surface mounting is generalized, there has been a demand for lighter, thinner, shorter and smaller optical coupling devices.

In view of the above problems, the present invention has a frameless structure in which thin film wiring is provided on a heat-resistant resin substrate, thereby achieving a thin structure and reducing the difference in coefficient of thermal expansion between the terminal and the mold resin. It is an object of the present invention to provide an optical coupling device that can reduce the occurrence of open and short defects due to peeling during this period and cracking of the mold resin without consideration.

[0008]

As shown in FIGS. 1 and 2, a light emitting element 14 and a light receiving element 15 are arranged so as to oppose each other so as to optically couple with each other. In the optical coupling device resin-sealed with the heat-resistant resin 28 and the light-shielding resin 29, the first recess 12 is formed on the surface of the heat-resistant insulating resin substrate 11, and the heat-resistant insulating resin substrate 11 is formed.
A second concave portion 13 is formed on the back surface of the first concave portion 12, a through hole 31 for light transmission is formed between the first concave portion 12 and the second concave portion 13, and the first concave portion 12 and the second concave portion 13 have a thin film shape. The three-dimensional wiring electrode portions 16 and 17 are formed, one of the light emitting element 14 and the light receiving element 15 is mounted on the electrode portion 16 of the first recess 12, and the light emitting element 14 is mounted on the electrode portion 17 of the second recess 13. And the other of the light receiving elements 15 is mounted,
The light emitting surface of the light emitting element 14 and the light receiving surface of the light receiving element 15 face each other.

According to a second aspect of the present invention, the hole wall 32 of the through hole 31 according to the first aspect is inclined so that the light from the light emitting element 14 is reflected and guided to the light receiving element 15. Is.

According to a third aspect of the present invention, there is provided a means for solving the problems, comprising the light emitting element 14 and the light receiving element 15 according to the first and second aspects.
A connecting means 27 for electrically connecting these is interposed between the electrode parts 16 and 17 on which they are mounted, and the connecting means 27 is made of a conductive adhesive, a solder paste or a solder bump.

[0011]

In the means for solving the problem according to claim 1, the heat-resistant insulating resin substrate 11 is provided with recesses 12 and 13 on both front and back surfaces thereof, and a through hole 31 is formed between them to form the recesses 12 and 13.
Then, thin-film three-dimensional wiring electrode portions 16 and 17 are formed. Then, the light emitting element 14 and the light receiving element 15 are mounted in the recesses 12 and 13 and face each other. After that, the translucent resin 28 and the light-shielding resin 29 are filled in the recesses 12 and 13 to manufacture an optical coupling device having a lead frameless structure. Then, the distance between the light emitting and receiving elements 14 and 15 can be set by the distance of the through hole 31 of the heat-resistant insulating resin substrate 11,
The mutual positioning of the 15 is accurate.

According to the second aspect, the light emitted from the light emitting element 14 is reflected by the inclined hole wall 32 of the through hole 31 to the light receiving element 15 to improve the light utilization efficiency.

In the third aspect, the elements 14 and 15 are formed in the recess 1
When mounting on the electrode parts 16 and 17 of 2 and 13, the connecting means 2
Connect via 7. Then, the mounting of each element becomes easy and the positional accuracy thereof is improved.

[0014]

1 is a sectional view showing an embodiment of an optical coupling device (photocoupler) according to the present invention, and FIG. 2 is a plan view thereof.

As shown in the figure, the optical coupling device of this embodiment has a light emitting element 14 and a light receiving element 15 in a heat-resistant insulating resin substrate 11.
And are opposed to each other so as to be optically coupled, and these are resin-sealed with a translucent resin 28 and a light-shielding resin 29.

A liquid crystal polymer or the like is used for the heat-resistant insulating resin substrate 11, and rectangular first recesses 12 and second recesses 13 for accommodating the light emitting element 14 and the light receiving element 15 are formed on both front and back surfaces thereof. ..

On the side walls and bottom walls of the first recess 12 and the second recess 13, thin-film three-dimensional wiring electrode parts 16, 17 are provided.
Are formed. The three-dimensional wiring electrode parts 16 and 17 are
Using u, Cu, Al, Ni, Ti or the like, a single layer or a multi-layer is formed by a wet plating method, a vapor deposition method, a sputtering method, a photolithography technique, an etching technique, or the like.
As shown in FIGS. 1 and 2, the three-dimensional wiring electrode portions 16 and 17 have connection terminals 16a and 17a on the front and back surfaces of the heat-resistant insulating resin substrate 11, respectively.
And through the wiring portions 16b and 17b of the through hole 30 to the connection terminals 16c and 17c on the mutually opposing surfaces of the heat resistant insulating resin substrate 11, respectively. As a result, when the surface side of the optical coupling device is surface-mounted by soldering or the like, the connection terminals 16a and 17c in FIG. 2 are externally connected to the wiring pattern on the external mounting substrate, and conversely, the back surface of the optical coupling device. When the side is surface-mounted, the connection terminals 16c and 17a are externally connected, so that either side of the back surface can be mounted (reversible), and the degree of freedom in circuit design is increased.

A through hole 31 for light transmission is formed between the central portions of the recesses 12 and 13. The through hole 3
The hole diameter of No. 1 is smaller than the chip size of each element 14, 15. The hole wall 32 of the through hole 31 reflects the light from the light emitting element 14 to the light receiving element 15 and guides it.
It has a trapezoidal cross section. The hole wall 32 has
In order to have glossiness, the three-dimensional wiring electrode parts 16, 1 are provided.
It is desirable to coat a metal film of Au, Ag, Cu, Al or the like which is discontinuous with 7.

The light emitting element 14 is mounted on the electrode portion 16 of the first concave portion 12, and the light receiving element 15 is mounted on the electrode portion 17 of the second concave portion 13, whereby the light emitting surface of the light emitting element 14 and the light receiving element 15 are mounted. The light receiving surface of is face-to-face.

The light emitting element 14 and the light receiving element 15,
Connection means 27 for electrically connecting the elements 14 and 15 with the electrodes 16 and 17 on which the elements 14 and 15 are mounted is interposed. As the connecting means 27, for example, a thermosetting anisotropic conductive adhesive in which carbon particles or metal particles are mixed in an insulating adhesive and then heated to have conductivity is used. Note that solder paste printing or solder bumps may be used as the connecting means 27, and these materials may be used separately for the light emitting side and the light receiving side.

The optical coupling device having the above structure is manufactured as follows. First, a plurality of heat-resistant insulating resin substrates 11 are integrally formed as a single large-sized substrate by injection molding. At this time, the recesses 12 and 13 and the through hole 31 are formed.

Next, the recesses 12 and 13 and the front and back surfaces of the heat-resistant insulating resin substrate 11 are selectively three-dimensionally plated to form the electrode portion 1.
6 and 17 are formed.

Further, connecting means 27 such as solder bumps is formed in advance on the light emitting element 14 and the light receiving element 15, and the electrode means 16, 17 of the recesses 12, 13 are formed by the connecting means 27.
Die-bond to. Then, when solder bumps are used as the connecting means 27, fusion connection is performed through a reflow process thereafter. In addition, this connecting means 27 is provided in advance in the electrode portion 1
It may be formed on the 6 and 17 side.

Further, if necessary, each element 14, 15
Wires are connected between the electrode parts 16 and 17. And
In order to protect them, the liquid translucent resin 28 is injected into the through holes 31 through the gaps between the elements 14 and 15 and the substrate 11 and then cured. Further, in order to shield ambient light, the upper layer portion is covered. The light-shielding resin 29 is filled and cured.

After that, the heat-resistant insulating resin substrate 11 as one large substrate is cut with a dicing saw to obtain individual optical coupling devices in a substantially rectangular parallelepiped shape.

The obtained optical coupling device may be surface-mounted on the external mounting substrate, depending on the circuit design.

As described above, the heat-resistant insulating resin substrate 11 is provided with the concave portions 12 and 13, respectively, and the electrode portions 16 and 17 are formed on the concave portions 12 and 13 by three-dimensional plating. After mounting the light receiving and emitting elements 14 and 15, the concave portions 12 and 13 are formed. By adopting a lead frameless structure in which the transparent resin 28 and the light shielding resin 29 are filled, the metal lead frame can be omitted, and it is not necessary to consider bending or deformation of the lead frame, which has been a conventional problem.

Further, the concave portion 12 of the heat-resistant insulating resin substrate 11,
By filling the transparent resin 28 and the light-shielding resin 29 inside 13, the difference in the coefficient of thermal expansion between the heat-resistant insulating resin substrate 11 and the resins 28 and 29 is conventionally used in the solder reflow treatment step. It is smaller than the difference in coefficient of thermal expansion between the metal lead frame and the molding resin.

Therefore, it is possible to prevent the peeling between the electrode portion on the heat-resistant insulating resin substrate 11 and each filling resin and the generation of these cracks, and to improve the electrical characteristics such as open and short. be able to.

Since the light emitting / receiving elements 14 and 15 can be accurately mounted in the concave portion of the heat resistant insulating resin substrate,
Product quality can be improved.

Further, since the hole wall 32 of the through hole 31 is an inclined surface and this is a reflection surface, the light utilization efficiency of the light beam emitted from the light emitting element 14 can be improved.

Therefore, as compared with the conventional optical coupling device,
It can improve its optical properties.

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.

[0034]

As is apparent from the above description, according to claim 1 of the present invention, the heat-resistant insulating resin substrate is provided with recesses on both front and back surfaces thereof, and through-holes for light transmission are formed between the recesses. Since the insulating resin substrate is provided with a three-dimensional electrode portion, the following effects can be expected by mounting the light receiving and emitting elements so as to face each other and molding the resin in the recess.

(1) Since the distance between the light receiving and emitting elements can be accurately set by the distance of the through hole, an error is less likely to occur even if the distance is set extremely short. Therefore, if the dimensions are designed so that the distance between the light receiving and emitting is short while ensuring the electrical insulation, both elements can be accurately positioned without error by this design and the dielectric breakdown due to being too close. Can be prevented, and a decrease in light utilization efficiency due to too far can be prevented. As a result, it is possible to significantly improve the yield and quality.

(2) Since the resin is molded in the concave portion of the heat-resistant insulating resin substrate, the difference in the coefficient of thermal expansion between the heat-resistant insulating resin substrate and the mold resin is small, and the mold resin is peeled off during the solder reflow process. Further, it is possible to suppress the occurrence of cracks and to provide a more reliable photo coupler.

(3) By adopting the lead frameless structure, it is possible to prevent the occurrence of defects due to bending and deformation of the metal lead frame during surface mounting on another substrate. Therefore, when the optical coupling device is mounted on the external mounting substrate, its positioning becomes easy.

(4) The lead frameless structure eliminates the need for a metal lead frame and makes it possible to provide a thinner and more compact optical coupling device.

According to the second aspect of the present invention, since the hole wall of the through hole is inclined and used as a reflecting surface, the light utilization efficiency of the light beam emitted from the light emitting element can be improved and the sensitivity can be further improved. Therefore, it becomes possible to provide an optical coupling device that can be used with a low current.

According to the third aspect, since the connecting means such as solder bumps is interposed between each element and the electrode portion directly connected thereto, the element can be easily mounted, and the light emitting / receiving element can be mounted. Since they can be easily arranged opposite to each other, the positional accuracy can be increased, and product variations can be suppressed. Further, since the manufacturing process can be shortened, it is possible to obtain an excellent effect when the price of the photo coupler can be further reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of an optical coupling device showing an embodiment of the present invention.

FIG. 2 is a plan view of an optical coupling device.

FIG. 3 is a sectional view of a conventional optical coupling device.

[Explanation of symbols]

 11 Heat-Resistant Insulating Resin Substrate 12 First Recess 13 Second Recess 14 Light-Emitting Element 15 Light-Receiving Element 16, 17 Electrode Section 27 Connecting Means 28 Light-Transparent Resin 29 Light-Shielding Resin 31 Through Hole 32 Hole Wall

Claims (3)

[Claims] 1. An optical coupling device in which a light emitting element and a light receiving element are opposed to each other so as to be optically coupled, and these are resin-sealed with a light-transmitting resin and a light-shielding resin. A first recess is formed on the front surface, a second recess is formed on the back surface of the heat resistant insulating resin substrate, a through hole for light transmission is formed between the first recess and the second recess, and the first recess and A thin-film three-dimensional wiring electrode part is formed in the second recess,
One of the light emitting element and the light receiving element is mounted on the electrode portion of the first recess, and the other of the light emitting element and the light receiving element is mounted on the electrode portion of the second recess, the light emitting surface of the light emitting element and the light receiving element. An optical coupling device characterized in that the light receiving surface of the element is face-to-face. 2. The optical coupling device according to claim 1, wherein a hole wall of the through hole is inclined so as to reflect and guide the light from the light emitting element to the light receiving element. 3. A connecting means for electrically connecting the light emitting element and the light receiving element according to claim 1 and an electrode portion on which the light emitting element and the light receiving element are mounted, and the connecting means is a conductive adhesive. An optical coupling device comprising an agent, a solder paste, or a solder bump.