JP2008226969A - Optical communication module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical communication module capable of reducing communication errors and improving reception sensitivity. <P>SOLUTION: The optical communication module A comprises: a substrate 1; a light-emitting element 2 mounted on the substrate 1; a light-receiving element 3 that has a light reception surface 3a and is mounted on the substrate 1; and a resin package 5 for covering the light-emitting element 2 and the light-receiving element 3. The optical communication module A also has a light-shielding film 31 for covering a side rising in the thickness direction of the substrate 1 of the light-receiving element 3. <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. 3 (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. The resin package 95 is formed with two lenses 95 a and 95 b positioned in front of the light emitting element 92 and the light receiving element 93. 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, for example, Si forming the light receiving element 93 is a material that transmits light to some extent. For this reason, a part of the light from the light emitting element 92 may be incident on the side surface of the light receiving element 93 after being reflected or refracted in the resin package 95. This light travels in the light receiving element 93 and is converted into an electromotive force for generating a light reception signal on the light receiving surface. This causes a communication error of the optical communication module X. Further, part of the infrared rays received by the light receiving element 93 through the lens 95 b is reflected or refracted in the light receiving element 93 and then emitted from the side surface of the light receiving element 93. Thereby, the receiving sensitivity of the optical communication module X will fall.

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 reducing communication errors and increasing reception sensitivity.

  An optical communication module provided by the present invention includes a substrate, a light emitting element mounted on the substrate, a light receiving surface, and a light receiving element mounted on the substrate, and the light emitting element and the light receiving element. An optical communication module including a covering resin package, wherein the light receiving element includes a light shielding film that covers a side surface of the light receiving element that stands in a thickness direction of the substrate.

  According to such a configuration, light that has passed through the resin package from the light emitting element toward the side surface of the light receiving element can be shielded by the light shielding film. Thereby, it is possible to prevent the light receiving element from erroneously generating a light reception signal due to light from the light emitting element. Therefore, communication errors of the optical communication module can be suppressed.

  In a preferred embodiment of the present invention, the light shielding film is made of a material having a high reflectance. A part of the light incident on the light receiving surface of the light receiving element reaches the side surface of the light receiving element by being refracted and reflected in the light receiving element. According to the configuration described above, since the light shielding film is formed of a material having a high reflectance, this light can be reflected into the light receiving element. The reflected light is eventually converted into an electromotive force that generates a light reception signal on the light receiving surface. Therefore, the light receiving sensitivity of the optical communication module can be increased.

  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, and a resin package 5. 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) that is electrically connected to the light emitting element 2, the light receiving element 3, and the driving IC 4 is formed. In the present embodiment, the substrate 1 has a thickness of about 0.06 to 0.10 mm, for example.

  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 part of the wiring pattern of the substrate 1.

  The light receiving element 3 is composed of, for example, a PIN photodiode formed using Si, and is configured to be able to generate an electromotive force corresponding to the amount of light when receiving infrared rays on the light receiving surface 3a. FIG. 2 is a partial cross-sectional perspective view showing only the light receiving element 3. As shown in the figure, the side surface of the light receiving element 3 is covered with a light shielding film 31. The light shielding film 31 is made of a metal such as Au, for example, and shields and reflects light including infrared rays.

  The light shielding film 31 is formed as follows, for example. First, a plurality of portions corresponding to the light receiving element 3 are formed by performing a semiconductor process on the Si wafer. Next, the Si wafer is cut by dicing to be divided into a plurality of light receiving elements 3. The plurality of divided light receiving elements 3 are supported by sticking the light receiving surface 3a to, for example, an adhesive tape. Then, an Au plating film is formed on the side surface of each light receiving element 3 by electroless plating. Thereby, the light shielding film 31 is obtained.

  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 light receiving surface 3 a of the light receiving element 3, and is configured to collect the infrared light transmitted toward the optical communication module A and to enter the light receiving surface 3 a of the light receiving element 3. ing. 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, the operation of the optical communication module A will be described.

  According to the present embodiment, the light that passes from the light emitting element 2 through the resin package 5 toward the side surface of the light receiving element 3 can be shielded by the light shielding film 31. Thereby, it is possible to avoid that the light receiving element 3 erroneously emits a light reception signal due to light from the light emitting element 2. Therefore, communication errors of the optical communication module A can be suppressed.

  A part of the light that has entered the light receiving element 3 through the lens 5 b reaches the side surface of the light receiving element 3 by being refracted and reflected in the light receiving element 3. Since the light shielding film 31 is made of Au having a high reflectance, this light can be reflected into the light receiving element 3. The reflected light is eventually converted into an electromotive force that generates a light reception signal on the light receiving surface 3a. Therefore, the light receiving sensitivity of the optical communication module A can be increased.

  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 shielding film referred to in the present invention is not limited to one made of Au, and is preferably formed of a metal having a relatively high reflectance such as Al. Moreover, this light shielding film is not limited to what consists of metals, For example, you may form by opaque materials, such as black resin. Even in this case, the effect of suppressing the communication error can be obtained by shielding the light from the light emitting element.

  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. It is a partial cross section perspective view which shows the light receiving element used for the optical communication module shown in FIG. It is sectional drawing which shows an example of the conventional optical communication module.

Explanation of symbols

A Optical communication module 1 Substrate 2 Light emitting element 3 Light receiving element 3a Light receiving surface 4 Driving IC
5 Resin package 5a, 5b Lens 31 Light shielding film

Claims (2)

A substrate,
A light emitting device mounted on the substrate;
A light receiving element having a light receiving surface and mounted on the substrate;
A resin package covering the light emitting element and the light receiving element;
An optical communication module comprising:
An optical communication module, comprising: a light shielding film that covers a side surface of the light receiving element that stands in a thickness direction of the substrate.   The light shielding film is an optical communication module made of a material having a high reflectance.

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