JP2008226967A - Optical communication module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical communication module that can be thinned and increase the output of a light-emitting element. <P>SOLUTION: The optical communication module A has: a substrate 1 having a front and a rear; the light-emitting element 2 so that light is emitted in a direction where the surface of the substrate 1 faces; a light-receiving element 3 mounted on the surface of the substrate 1; and a resin package 5 for covering the light-emitting element 2 and the light-receiving element 3. In the optical communication module A, a through hole 1a is formed on the substrate 1. Further, the substrate 1 has a first conductor layer 6A for blocking the through hole 1a from the front side, and a second conductor layer 6B for covering a part facing the through hole 1a at least in the first conductor layer 6A from the first front side of the substrate 1. The light-emitting element 2 is mounted to a part for covering the first conductor layer 6A in the second conductor layer 6B. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical communication module used for bidirectional communication in an electronic device.

  An optical communication module including a light emitting element and a light receiving element is used for bidirectional communication in electronic devices such as notebook computers, mobile phones, and electronic notebooks. Such optical communication modules include, for example, IrDA compliant infrared data communication modules.

  An example of this type of conventional optical communication module is shown in FIG. 6 (see, for example, Patent Document 1). The optical communication module X shown in the figure includes a light emitting element 92, a light receiving element 93, a driving IC 94, and a resin package 95 mounted on a substrate 91 made of glass epoxy resin. The light emitting element 92 is configured to emit infrared light. The light receiving element 93 is configured to generate an electromotive force according to the amount of infrared light received on the light receiving surface. The resin package 95 is formed of a transparent epoxy resin. In the resin package 95, two lenses 95a and 95b positioned in front of the light emitting element 92 and the light receiving element 93 are formed. The infrared rays emitted from the light emitting element 92 are emitted with the directivity enhanced by the lens 95a. On the other hand, the infrared rays traveling from above in the figure are condensed onto the light receiving element 93 by the lens 95b. In this way, bidirectional communication using infrared rays by the optical communication module X is performed.

  However, the optical communication module including the optical communication module X is strongly demanded to be thin. The portion including the light emitting element 92 in the optical communication module X includes the thickness of the portion of the resin package 95 where the lens 95a is formed in addition to the thickness of the light emitting element 92, and thus is a relatively thick portion. . In order to reduce the thickness of the optical communication module X, it has been an issue to thin the portion including the light emitting element 92. Furthermore, it is required to extend the communicable distance and ensure communication. For this purpose, when the output of the light emitting element 92 is increased, the amount of heat generated from the light emitting element 92 increases. The substrate 91 and the resin package 95 are both made of a material having a relatively low thermal conductivity. For this reason, measures for heat dissipation of the light emitting element 92 have been a problem.

JP 2002-324916 A

  The present invention has been conceived under the circumstances described above, and an object of the present invention is to provide an optical communication module capable of achieving a reduction in thickness and an increase in output of a light emitting element.

  An optical communication module provided by the present invention includes a substrate having a front surface and a back surface, a light emitting element mounted so as to emit light in a direction in which the front surface of the substrate faces, and a light receiving element mounted on the surface of the substrate And a resin package that covers the light emitting element and the light receiving element, wherein the substrate has a through-hole formed therein, and a first conductor layer that closes the through-hole from the back side; A second conductor layer that covers at least a portion of the first conductor layer facing the through hole from the surface side of the substrate, and the light emitting element includes the second conductor layer. It is mounted in the part which covers the said 1st conductor layer.

  According to such a configuration, the light emitting element and the substrate do not overlap in the thickness direction of the substrate. Thereby, the thickness of the part including the light emitting element in the optical communication module is substantially the sum of the light emitting element and the resin package, and does not include the thickness of the substrate. Therefore, the optical communication module can be thinned. In addition, heat generated from the light emitting element is transmitted to the first conductor layer through the second conductor layer. Since the first conductor layer is exposed on the back side of the substrate, it is advantageous for heat dissipation. Accordingly, the output of the light-emitting element can be increased, and the communicable distance can be extended and the communication can be ensured.

  In a preferred embodiment of the present invention, the through hole has a cross-sectional dimension that increases from the back surface to the front surface, and the second conductor layer further covers the inner surface of the through hole. According to such a configuration, the light emitted from the light emitting element to the side is reflected to the surface side of the substrate by the portion of the second conductor layer that covers the inner surface of the through hole. Thereby, it is possible to increase the rate at which the light from the light emitting element is emitted to the outside of the optical communication module. This is advantageous for extending the communicable distance and ensuring communication.

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

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

  FIG. 1 shows an example of an optical communication module according to the present invention. The optical communication module A of this embodiment includes a substrate 1, a light emitting element 2, a light receiving element 3, a driving IC 4, a resin package 5, a first conductor layer 6A, and a second conductor layer 6B. The optical communication module A is configured to be capable of two-way communication using infrared rays in accordance with, for example, IrDA (Infrared Data Association) standards.

  The board | substrate 1 is formed in planar view long rectangular shape as a whole with glass epoxy resin, for example. On the surface of the substrate 1, a wiring pattern (not shown) for conducting the light emitting element 2, the light receiving element 3, and the driving IC 4 is formed. A through hole 1a is formed in the substrate 1 so as to penetrate the substrate 1 from the front surface to the back surface. The through hole 1a has a divergent shape in which the cross-sectional dimension is increased from the back surface to the front surface of the substrate 1, and is a size that can accommodate the light emitting element 2. In the present embodiment, the substrate 1 has a thickness of about 0.06 to 0.10 mm, for example.

  On the substrate 1, a first conductor layer 6A and a first conductor layer 6B are formed. The first conductor layer 6A and the second conductor layer 6B are thin films made of, for example, Cu, Ni, or alloys thereof. The first conductor layer 6 </ b> A is provided at a position where the through hole 1 a is blocked from the back side of the substrate 1. The second conductor layer 6B covers the inner surface of the through hole 1a and the portion of the first conductor layer 6A that faces the through hole 1a from the surface side of the substrate 1.

  The light emitting element 2 is made of, for example, an infrared light emitting diode capable of emitting infrared light. The light emitting element 2 is mounted on a portion of the second conductor layer 6B that is in contact with the first conductor layer 6A.

  The light receiving element 3 is composed of, for example, a PIN photodiode formed using Si, and is configured to generate an electromotive force according to the amount of light when infrared light is received on the light receiving surface.

  The drive IC 4 is for controlling transmission / reception operations by the light emitting element 2 and the light receiving element 3. The driving IC 4 is connected to the wiring pattern by a wire, and is connected to the light emitting element 2 and the light receiving element 3 through the wiring pattern.

  The resin package 5 is formed of, for example, an epoxy resin. By forming the resin package 5 using an epoxy resin containing a dye, the resin package 5 transmits infrared rays while shielding most visible light. The resin package 5 is formed by a transfer molding method or the like, and is provided so as to cover the light emitting element 2, the light receiving element 3, and the driving IC 4. Two lenses 5 a and 5 b are integrally formed in the resin package 5. The lens 5a is located in front of the light emitting element 2, and is configured to emit infrared rays emitted from the light emitting element 2 with enhanced directivity. The lens 5 b faces the surface of the light receiving element 3, and is configured to collect infrared rays transmitted toward the optical communication module A and to enter the light receiving surface of the light receiving element 3. In the present embodiment, the thickness of the resin package 5 other than the part where the lenses 5a and 5b are formed is, for example, about 0.3 mm. The resin package 5 may be configured to have translucency with respect to light of most wavelengths.

  Next, an example of a method for manufacturing the optical communication module A will be described below with reference to FIGS. These drawings show a process of forming the first conductor layer 6A and the second conductor layer 6B on the substrate 1. FIG.

  First, as shown in FIG. 2, a substrate 1 made of, for example, a glass epoxy resin is prepared. A thin film made of Cu, Ni, or an alloy thereof is formed on the back surface of the substrate 1. The first conductor layer 6A is formed by patterning the thin film using etching or the like.

  Next, as shown in FIG. 3, the through hole 1a is formed. For example, laser light is used to form the through hole 1a. The laser beam is absorbed by the substrate 1 so that the substrate 1 can be perforated. On the other hand, the laser beam is hardly absorbed by the first conductor layer 6A made of Cu, for example. For this reason, the drilling process by the laser beam is started from the surface of the substrate 1 and is finished when the laser beam reaches the first conductor layer 6A. As a result, it is possible to form the through hole 1a closed by the first conductor layer 6A.

  Next, as shown in FIG. 4, the second conductor layer 6B is formed. The second conductor layer 6B is formed by forming a thin film made of Cu, Ni, or an alloy thereof on the surface side of the substrate 1 and then patterning the thin film using etching or the like. As a result, it is possible to form the second conductor layer 6B that covers the inner surface of the through hole 1a and the portion of the first conductor layer 6A that faces the through hole 1a.

  FIG. 5 is an enlarged side view of the optical communication module A. FIG. As clearly shown in the figure, terminals 7 are formed on the side surface of the substrate 1. The terminal 7 is used for mounting the optical communication module A on a circuit board. The terminal 7 is constituted by a first conductor layer 6C and a second conductor layer 6D made of Cu, Ni, or an alloy thereof, and is formed along a concave portion 1b having a semicircular cross section. The first conductor layer 6 </ b> C covers the recess 1 b from the surface side of the substrate 1. The second conductor layer 6D covers the inner surface of the recess 1b and the portion of the first conductor layer 6C that faces the recess 1b from the back side of the substrate 1.

  Such a terminal 7 can be formed together with the first conductor layer 6A and the second conductor layer 6B described above. That is, the first conductor layer 6A and the first conductor layer 6C are formed by thin film formation and patterning made of Cu, Ni, or an alloy thereof. Subsequently, the through-hole 1a and the recessed part 1b are formed using a laser beam. Then, the second conductor layer 6B and the second conductor layer 6D are formed by thin film formation and patterning made of Cu, Ni, or an alloy thereof. Usually, in the formation of the terminal 7, after forming a through hole in a substrate material capable of taking a plurality of substrates 1, the substrate material is divided so as to divide the through hole, thereby forming the recess 1 b. .

  Next, the operation of the optical communication module A will be described.

  According to this embodiment, the light emitting element 2 is accommodated in the through hole 1 a of the substrate 1. For this reason, the light emitting element 2 and the substrate 1 do not overlap in the thickness direction of the substrate 1. Thereby, the thickness of the portion including the light emitting element 2 in the optical communication module A is substantially the sum of the thickness of the light emitting element 2 and the portion of the resin package 5 where the lens 5a is formed. Is not included. Therefore, the optical communication module A can be thinned. In particular, in this embodiment, the thickness of the substrate 1 is about 0.06 to 0.10 mm, and the thickness of the resin package 5 other than the portion where the lenses 5a and 5b are formed is about 0.3 mm. It is supposed to be thin.

  The heat generated from the light emitting element 2 is transferred to the first conductor layer 6A through the second conductor layer 6B. Since the first conductor layer 6A is exposed on the back side of the substrate 1, it is advantageous for heat dissipation. Therefore, it is possible to increase the output of the light emitting element 2, and it is possible to extend the communicable distance and ensure the communication. In particular, if, for example, a conductor layer having a larger area than the first conductor layer 6A is formed in a portion where the first conductor layer 6A is in contact with the circuit board on which the optical communication module A is mounted, the light emitting element It is suitable for promoting the heat radiation from 2.

  Since the through hole 1a is divergent from the back surface to the front surface of the substrate 1, the light emitted from the light emitting element 2 to the side covers the inner surface of the through hole 1a in the second conductor layer 6B. The portion is reflected to the surface side of the substrate 1. Thereby, it is possible to increase the rate at which the light from the light emitting element 2 is emitted to the outside of the optical communication module A through the lens 5a. This is advantageous for extending the communicable distance and ensuring communication.

  The optical communication module according to the present invention is not limited to the above-described embodiment. The specific configuration of each part of the optical communication module according to the present invention can be modified in various ways.

  The light emitting element and the light receiving element are not limited to those capable of emitting or receiving infrared rays, and may be those capable of emitting or receiving light of various wavelengths including visible light. That is, the optical communication module is not limited to the infrared data communication module, and may be, for example, a communication system using visible light.

It is sectional drawing which shows an example of the optical communication module which concerns on this invention. FIG. 5 is a cross-sectional view showing a step of forming a first conductor layer on a substrate in the example of the method for manufacturing the optical communication module shown in FIG. FIG. 3 is a cross-sectional view showing a process of forming a through hole in a substrate in the example of the method for manufacturing the optical communication module shown in FIG. FIG. 7 is a cross-sectional view showing a step of forming a second conductor layer on a substrate in the example of the method for manufacturing the optical communication module shown in FIG. 1. It is a principal part enlarged side view which shows an example of the optical communication module which concerns on this invention. It is sectional drawing which shows an example of the conventional optical communication module.

Explanation of symbols

A Optical communication module 1 Substrate 1a Through hole 2 Light emitting element 3 Light receiving element 4 Driving IC
5 Resin Package 5a, 5b Lens 6A First Conductor Layer 6B Second Conductor Layer

Claims (2)

A substrate having a front surface and a back surface;
A light emitting element mounted so as to emit light in a direction in which the surface of the substrate faces,
A light receiving element mounted on the surface of the substrate;
A resin package covering the light emitting element and the light receiving element;
An optical communication module comprising:
A through hole is formed in the substrate,
A first conductor layer that covers the through hole from the back side; and a second conductor layer that covers at least a portion of the first conductor layer facing the through hole from the surface side of the substrate. ,
The optical communication module, wherein the light emitting element is mounted on a portion of the second conductor layer that covers the first conductor layer. The through-hole has a larger cross-sectional dimension from the back surface to the surface,
The optical communication module according to claim 1, wherein the second conductor layer further covers an inner surface of the through hole.

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