JPH11345999A - Photoelectric conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve intensity of radiation light or receiving light of a photoelectric conversion device constituted by using a printed board. SOLUTION: A first printed board 12a has a through hole whose aperture on the surface is larger than that on the back, and the inner surface of the through hole is plated with metal. An electrode pattern 19 for mounting a photoelectric conversion element 14 is formed on the surface of a second printed board 12b. The first printed board 12a is stuck on the second printed board 12b in such a manner that the central part of the through hole coincides with the central part of the electrode pattern 19. The photoelectric conversion element 14 is mounted on the electrode pattern 19.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric conversion device in which a photoelectric conversion element is mounted on a structure in which first and second printed boards are bonded.

[0002]

2. Description of the Related Art Electronic components are required to be mounted at higher densities so as to be able to cope with miniaturization and weight reduction of devices, and photoelectric conversion devices are becoming increasingly smaller. In order to meet these demands, recently, as shown in the cross-sectional view of FIG. 4, a photoelectric conversion device using a printed circuit board having a high degree of freedom in circuit pattern design and capable of high-density mounting has been put to practical use. I have.

In the conventional photoelectric conversion device shown in FIG. 4, for example, a solid-chip type light emitting semiconductor element 14 is bonded and fixed to one electrode pattern 19 on a printed circuit board 12 on the electrode side on the back surface, and on the front surface side. Is connected by wire 13
It is connected to the other electrode pattern 19, and is further sealed with the translucent resin 18 and the lens surface 11.

According to this photoelectric conversion device, the light emitted from the light-emitting semiconductor element 14 is a divergent light having a spread, and thus is not suitable for a light source having a high radiated light intensity in a predetermined direction. In order to obtain the above, the supply current of the light emitting semiconductor element 14 must be increased.

[0005] In addition, when the divergent light is condensed to increase the intensity of radiated light in a predetermined direction, for example, a reflector is provided.
In the case of using a conventional printed circuit board, there has not been found any one that can cope with the problem.

[0006]

In the case of a printed circuit board,
The substrate material is paper-based phenolic resin, paper-based epoxy resin, synthetic fiber fabric-based epoxy resin, glass fabric-based epoxy resin, etc., and the substrate itself obtained by plastic processing is used as it is as a reflector. It is difficult.

On the printed circuit board, there is a method of laminating a pattern such as a copper foil to form a reflector. However, forming a reflector having a thickness greater than the thickness of the light emitting semiconductor element requires a multi-layer pattern. This is difficult and costly.

Further, the printed circuit board itself has a lower heat radiation property than a lead frame using metal, and is manufactured by providing a heat radiating pattern on the printed circuit board or by connecting the printed circuit board to a heat sink plate. It was necessary to enhance the heat dissipation. That is, increasing the current in order to increase the intensity of the radiated light of the photoelectric conversion device also creates a problem of improving heat dissipation.

[0009]

In order to solve the above-mentioned problems, a photoelectric conversion device according to the present invention has a through hole having a larger diameter on the front side and a reflective layer formed on the inner surface of the through hole. A first printed circuit board and a second printed circuit board on which a photoelectric conversion element is mounted on an electrode pattern on the front surface are bonded in a state where the photoelectric conversion element is placed at the center of the back surface of the through hole, and the photoelectric conversion element is bonded. This is a structure in which the conversion element is sealed with a translucent resin. Thereby, the scattered light of the photoelectric conversion element is reflected by the reflection layer on the inner surface of the through hole,
The intensity of the emitted light guided in a predetermined direction can be increased.

[0010] In the photoelectric conversion device of the present invention, the shape of the through hole may be a part of a surface selected from the group consisting of a conical, a semicircular, a spheroidal, and a paraboloidal shape, or simply a mortar. Those having a part of the shape surface, the conical shape is selected from a conical shape and a polygonal pyramid such as a triangle and a square.

The reflective layer is formed and used as a metal plating layer or a silver paste coating layer.

Further, the first printed circuit board and the second printed circuit board can be bonded with a conductive paste.

The photoelectric conversion element will be described by taking a light emitting semiconductor element as an example. However, a similar effect can be obtained with a light receiving semiconductor element to improve its function.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view of one embodiment of the present invention. In this photoelectric conversion device, a first printed circuit board 12a and a second printed circuit board 12b are bonded by an adhesive 15, and The element 14 is mounted on the electrode pattern 19 on the second printed circuit board 12b.

On the first printed circuit board 12a, for example, a mortar-shaped through-hole having a diameter on the front side larger than that on the back side is formed so as to efficiently reflect light from the light emitting semiconductor element 14, A reflective layer 17 for reflecting light is formed on the inner surface of the through hole by a metallic bright plating layer. In addition, a metal wiring pattern 16 for enabling conductive connection is provided on the first printed circuit board 12 a, and is connected to one electrode of the light emitting semiconductor element 14 by a wire 13.

The second printed circuit board 12b has an electrode pattern 19 on the front surface side, and the other electrode of the light emitting semiconductor element 14 is mounted on the electrode pattern 19 by bonding. The back surface of the light emitting semiconductor element 14 is bonded to the bottom surface of the through hole 12a with an adhesive 15 in a state where the light emitting semiconductor element 14 is located at the center of the bottom of the through hole.

Further, the surface of the second printed circuit board 12b is molded with a translucent resin 18, and the lens surface 11 is provided at a position on the surface of the through hole having a large surface hole diameter.

With the above configuration, the light emitted from the light emitting semiconductor element 14 is reflected on the reflection surface 17 formed on the inner surface of the through hole.
Then, the light can be emitted to the outside through the translucent resin 18 and the lens surface 11, and the light emitted from the side surface of the light emitting semiconductor element 14 can be effectively used.

Further, by expanding the electrode pattern 19 on which the light emitting semiconductor element 14 is mounted, a photoelectric conversion element having excellent heat dissipation can be manufactured.

FIGS. 2A to 2G are process flow sectional views showing a procedure for manufacturing a photoelectric conversion device according to an embodiment of the present invention. Hereinafter, a manufacturing method will be described with reference to FIG.

As shown in FIG. 2A, a double-sided copper foil 20 is provided on first and second printed circuit boards 21a and 21b, respectively.
The two printed circuit boards on which are formed are prepared.

As shown in FIG. 2B, a mortar-shaped through-hole 22 having a larger diameter on the front side than on the rear side is formed on the first printed circuit board 21a by laser processing, cutting, or the like. I do. The through hole 22 at this time
The inner surface shape is a mortar-shaped surface where the side on which the light-emitting semiconductor element is mounted has a small bottom, but in addition, a polygonal pyramid, a cone, a rotating semi-circular surface, a spheroidal surface, or a paraboloid of revolution. By selecting a planar shape, a shape suitable for reflecting light emitted from the light emitting semiconductor element can be obtained.

Next, as shown in FIG. 2C, an electrode wiring pattern 23 is formed on the second printed board 21b, and a wiring pattern 24 is formed on the first printed board 21a by etching.

Next, as shown in FIG. 2D, metal plating is applied to the through-hole portion of the first printed circuit board 21a to form a reflection layer 25 capable of reflecting the radiated light from the light emitting semiconductor element.

Then, as shown in FIG. 2 (e), the first printed circuit board 21a and the second printed circuit board 21b are bonded to each other using an adhesive 26 to form an integrated structure as shown in FIG. 2 (f). The printed circuit board on which the photoelectric conversion element was mounted was obtained by bonding to the substrate.

Next, as shown in FIG. 2 (g), a light emitting semiconductor element 28 is mounted on the electrode wiring pattern 23 and connected by wires 27, and finally, a unit structure as shown in FIG. To finish.

As a material of the adhesive for bonding the first and second printed circuit boards, a conductive paste can be used. Accordingly, materials commonly used in the manufacture of the photoelectric conversion device can be used in combination, which is convenient in terms of manufacturing control.

In the case of a printed circuit board, the reflection characteristics are improved by applying silver plating on a copper-based plating layer as a material of the reflection layer for improving the efficiency of the photoelectric conversion element, and a more excellent photoelectric conversion is achieved. A device can be obtained. It is particularly effective in the case of a photoelectric conversion device using a light emitting semiconductor element of visible light color.

Further, as shown in FIG. 3, before the chip of the light-emitting semiconductor element is mounted on the inner surface of the through-hole by a coating means, for example, a paste pin 29, which can be mounted on the mounting equipment for assembling this type of photoelectric conversion device. It is also possible to apply a silver paste 30 to form a reflective layer. According to this, there is an advantage that the process equipment is simplified and the manufacturing process is also simplified. In addition, the application of the silver paste to the through-holes for forming the reflective layer may be performed after plating the through-holes, or may be applied directly to the through-holes without plating. It goes without saying that a special effect can be obtained.

In each of the above embodiments, the case where a light emitting semiconductor element is used as a photoelectric conversion element has been described. However, the present invention is applicable to a case where a light receiving semiconductor element is used instead of a light emitting semiconductor element to receive light. The effect of increasing the received light intensity is obtained.

[0032]

As described above, according to the present invention, it is possible to provide a photoelectric conversion device having a high radiation light (light reception) intensity and an excellent effect.

Further, by forming the reflective layer by plating through holes or applying silver paste to the surfaces of the through holes, the function of the photoelectric conversion element can be effectively utilized, and the intensity of emitted light (light reception) can be increased.

Further, by widening the electrode pattern, a photoelectric conversion element having more excellent heat dissipation can be easily manufactured. Even if the current value is increased, the heat dissipation is good, and higher radiation light (light receiving) can be obtained. ) Even in a photoelectric conversion device requiring strength, the performance can be sufficiently exhibited.

In addition, since many methods for manufacturing a printed multilayer board can be used, there is an advantage that it can be manufactured easily and at low cost.

In the photoelectric conversion device of the present invention, the assembly equipment used for a normal photoelectric conversion device can also be used in the manufacturing method, and the photoelectric conversion device using a printed circuit board can be manufactured more easily. Yes, it is also beneficial for cost reduction.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a photoelectric conversion device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a manufacturing process flow of the photoelectric conversion device according to one embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a manufacturing process of the photoelectric conversion device according to one embodiment of the present invention.

FIG. 4 is a cross-sectional view of a conventional photoelectric conversion device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Lens surface 12a 1st printed board 12b 2nd printed board 13 Wire 14 Light emitting semiconductor element 15 Adhesive 16 Wiring pattern 17 Reflective layer 18 Translucent resin 19 Electrode pattern 20 Double-sided copper foil

Claims (5)

[Claims] 1. A first printed circuit board having a through-hole having a larger diameter on the front side and a reflective layer formed on an inner surface of the through-hole, and a second substrate having a photoelectric conversion element mounted on an electrode pattern on the front side. Wherein the photoelectric conversion element is bonded to the printed circuit board of No. 2 in a state where the photoelectric conversion element is placed in the center of the back surface side of the through hole, and the photoelectric conversion element is sealed with a translucent resin. . 2. An inner surface of the through-hole has a part of a surface selected from the group consisting of a cone, a semicircle of revolution, a spheroid and a paraboloid of revolution, or a part of a mortar-like surface. 1
3. The photoelectric conversion device according to claim 1. 3. The photoelectric conversion device according to claim 1, wherein the reflection layer is formed of a metal plating layer. 4. The photoelectric conversion device according to claim 1, wherein the reflection layer is formed of a silver paste coating layer. 5. The photoelectric conversion device according to claim 1, wherein the first printed board and the second printed board are bonded with a conductive paste.