JP2007035810A - Optical communication module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical module which can be miniaturized. <P>SOLUTION: An infrared data communication module A1 is provided with a substrate 1 having a recess 11 opening toward the front surface formed thereon, and a light-emitting element 2 mounted on a bottom surface 11a of the recess 11. In this module A1, the recess 11 has a first side surface 11b slanted so as to face the front surface side for a perpendicular direction of the substrate 1; and a second side surface 11c positioned nearer the bottom surface 11a than the first side surface 11b, and having an inclined angle for the perpendicular direction of the substrate 1 smaller than that of the first side surface 11b. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical communication module used for data communication using infrared rays, for example.

  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 infrared data communication module is shown in FIG. The infrared data communication module X includes a substrate 90, a light emitting element 92 mounted on the substrate 90, and a resin package 93 having a lens portion. A concave portion 91 is formed in the substrate 91, and a light emitting element 92 is mounted on the bottom surface 91a. The side surface 91b of the concave portion 91 has a circular cross section, is inclined with respect to the normal direction of the substrate 90, and faces upward in the drawing. The light emitting element 92 is configured to be able to emit infrared rays upward and laterally in the drawing. If the inner surface of the recess 91 is covered with metal plating, the bottom surface 91a and the side surface 91b can be made reflective surfaces with relatively high reflectivity. As a result, light traveling from the light emitting element 92 to the side in the figure can be reflected by the side surface 91b and directed upward in the figure. As described above, in the infrared data communication module X, the data communication is ensured by increasing the amount of emitted infrared light.

  Electronic devices such as notebook computers, mobile phones, and electronic notebooks are becoming smaller year by year. In addition, in order to increase the functionality of these electronic devices, electronic components mounted on these electronic devices are markedly mounted with high density. For this reason, the infrared data communication module X is also strongly requested to be downsized. In particular, in order to reduce the width of the substrate 90 (the dimension in the depth direction in the figure), it is necessary to reduce the diameter of the side surface 91b. The size of the side surface 91 b is substantially proportional to the size of the light emitting element 92. However, it is difficult to reduce the size of the light emitting element 92. This is because if the light emitting element 92 is made smaller, the amount of light emitted from the light emitting element 92 becomes smaller, causing problems such as a reduction in the communicable distance by the infrared data communication module X. As described above, there is still room for improvement in the downsizing of the infrared data communication module X.

JP 2003-244077 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 that can be miniaturized.

  In order to solve the above problems, the present invention takes the following technical means.

  An optical communication module provided by the present invention is an optical communication module comprising a substrate having a recess formed on a surface thereof, and a light emitting element mounted on the bottom surface of the recess, wherein the recess is the substrate. A first side surface inclined so as to face the surface side with respect to the normal direction, and a position closer to the bottom surface than the first side surface, and an inclination angle of the substrate with respect to the normal direction is greater than that of the first side surface. And a second side surface that is also small.

  According to such a configuration, for example, the planar view size of the concave portion can be reduced by the amount of the second side surface as compared with a configuration in which the entire side surface of the concave portion is a tapered surface having a certain inclination angle. it can. Thereby, size reduction of the said optical communication module can be achieved. On the other hand, the light from the light emitting element can be reflected by the first side surface and emitted efficiently.

  In a preferred embodiment of the present invention, the first side surface is connected to the surface of the substrate, the inclination angle with respect to the normal direction of the substrate is constant, and the second side surface is connected to the bottom surface. And a cylindrical shape extending in the direction perpendicular to the substrate. According to such a configuration, the area of the first side surface can be increased, which is advantageous in efficiently emitting light from the light emitting element. The second side surface has a shape that does not spread at all in the direction in which the substrate extends. Therefore, it is suitable for downsizing of the optical communication module.

  In a preferred embodiment of the present invention, the first side surface and the second side surface are directly connected. Such a configuration is suitable for increasing the area of the first side surface.

  In a preferred embodiment of the present invention, the first side surface has an inclination angle of 30 to 40 ° with respect to the normal direction of the substrate. According to such a configuration, most of the light traveling obliquely upward from the light emitting element is suitable for directing in the perpendicular direction of the substrate.

  In a preferred embodiment of the present invention, a metal film covering at least the first side surface is further provided. According to such a configuration, the first side surface can be a surface having a relatively high reflectance, which is advantageous for efficiently emitting light from the light emitting element.

  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.

  1 and 2 show a first embodiment of an infrared data communication module according to the present invention. As shown in FIG. 1, the infrared data communication module A <b> 1 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, and wires 8. 2 is a plan view when the infrared data communication module A1 is viewed from above in FIG. 1, and for convenience, the resin package 5, the wires 8, and the wiring pattern to which the wires 8 are connected are omitted.

  As shown in FIG. 2, the substrate 1 has a rectangular shape in plan view as a whole, and is formed of a resin such as glass epoxy. As shown in FIG. 1, a recess 11 is formed in the substrate 1. The recess 11 is for mounting the light emitting element 2 in a state where it is buried in the surface of the substrate 1. The recess 11 has a function of efficiently directing infrared rays emitted from the light emitting element 2 upward in FIG.

The recess 11 has a bottom surface 11a, a first side surface 11b, and a second side surface 11c. The light emitting element 2 is mounted on the bottom surface 11a via the metal film 6. The first side surface 11 b is connected to the upper surface of the substrate 1 in the figure, and is a tapered surface having a circular cross section inclined with respect to the normal direction N of the substrate 1. Since the first side surface 11b is covered with the metal film 6, the first side surface 11b is a reflective surface having a relatively high reflectance. In the present embodiment, the inclination angle θ ₁ of the first side surface 11b with respect to the normal direction N is set to 35 °. In order to appropriately exhibit the function of reflecting infrared rays to be described later, the inclination angle θ ₁ is preferably about 30 to 40 °. The second side surface 11 c is connected to the bottom surface 11 a and the first side surface 11 b and has a cylindrical shape extending in the perpendicular direction N. The recess 11 is subjected to machining such as forming the first side surface 11b from the upper surface side of the substrate 1 using a cone-shaped drill blade and then forming the second side surface 11c using a cylindrical drill. It is formed by. In the present embodiment, the recess 11 has a depth of about 0.18 to 0.23 mm. The first side surface 11b has a depth of about 0.08 to 0.17 mm, an upper end diameter in FIG. 1 of about 0.8 to 1.2 mm, and a lower end diameter of about 0.6 to 0.6 mm. . The second side surface 11c has a depth of about 0.1 mm and a diameter of about 0.6 to 0.7 mm. The second side surface 11c preferably has a height of about 0.06 to 0.1 mm in accordance with the height of the light emitting element 2 described later.

  The recess 11 is covered with the metal film 6. The metal film 6 is for bonding the light emitting element 2 to the bottom surface 11a and for making the first side surface 11b a surface having a relatively high reflectance. The metal film 6 has a laminated structure composed of, for example, a Cu layer, a Ni layer, and an Au layer. The thicknesses of these Cu layer, Ni layer, and Au layer are, for example, about 5 μm, 5 μm, and 0.5 μm, respectively. A portion of the metal film 6 that covers the bottom surface 11 a is used for bonding the light emitting element 2. Moreover, the part which covers the 1st side surface 11b among the metal films 6 is utilized for reflecting the infrared rays which went to the 1st side surface 11b among the lights emitted from the light emitting element 2, upward in the figure. As shown in FIG. 2, the metal film 6 is formed with a donut-shaped collar portion in plan view so as to surround the recess 11. A portion extending from the flange portion is connected to a terminal 7 for ground connection. For example, the metal film 6 is formed by sequentially performing a plating process using Cu, Ni, and Au, and then performing a patterning process using etching.

  As shown in FIG. 2, a plurality of terminals 7 are formed on one end edge of the substrate 1. The terminal 7 is formed so as to cover the groove 12 of the substrate 1. The groove 12 has an arc shape in cross section and extends in the perpendicular direction N of the substrate 1 shown in FIG. In FIG. 2, the terminal 7 located at the right end in the drawing is for ground connection.

  The light emitting element 2 is made of, for example, an infrared light emitting diode capable of emitting infrared rays, and is connected to a wiring pattern illustrated by wires 8 as shown in FIG. In the present embodiment, the light emitting element 2 has a plan view size of about 0.35 mm square and a height of about 0.16 mm. That is, the light emitting element 2 is surrounded by the second side surface 11 c of the recess 11 at a portion corresponding to 2/3 of the height.

  The light receiving element 3 is composed of, for example, a PIN photodiode capable of sensing infrared rays, and is connected to the wiring pattern illustrated by the wire 8. A light receiving surface (not shown) is formed on the upper surface of the light receiving element 3 in FIG. When infrared rays are irradiated on the light receiving surface, an output signal corresponding to the intensity of the infrared rays is output from the light receiving element 3.

  The driving IC 4 is for driving and controlling the transmission / reception operation by the light emitting element 2 and the light receiving element 3. The driving IC 4 is connected to the wiring pattern shown by the wire 8 and is connected to the light emitting element 2 and the light receiving element 3 through the wiring pattern.

  The resin package 5 is made of, for example, an epoxy resin containing a pigment, and has no translucency for light of any wavelength other than infrared rays, but has transparency for infrared rays. The resin package 5 is formed by a transfer molding method or the like, and is provided on the substrate 1 so as to cover the light emitting element 2, the light receiving element 3, and the driving IC 4 as shown in FIG. Two lens portions 51 and 52 are integrally formed in the resin package 5. Each of the lens portions 51 and 52 has a shape bulging upward in the drawing. The lens unit 51 is positioned in front of the light emitting element 2 and is configured to emit infrared light emitted from the light emitting element 2 while condensing. The lens unit 52 is positioned in front of the light receiving element 3 and is configured to collect the infrared light transmitted to the infrared data communication module A <b> 1 and enter the light receiving element 3.

  Next, the operation of the infrared data communication module A1 will be described.

According to this embodiment, the infrared rays emitted from the light emitting element 2 can be emitted efficiently. The first side surface 11b located on the upper side in FIG. 1 in the recess 11 is a so-called tapered surface. Infrared rays L emitted from the light emitting element 2 obliquely upward at a relatively shallow angle travel toward the first side surface 11b. The infrared rays L are reflected by the metal film 6 covering the first side surface 11 b and directed toward the lens unit 51. Therefore, most of the infrared rays emitted from the light emitting element 2 can be emitted outside the infrared data communication module A1 through the lens unit 51. In particular, the first side surface 11 b has an inclination angle θ ₁ with respect to the normal direction N of the substrate 1 of 35 °. This is suitable for efficiently reflecting the infrared rays L from the light emitting element 2 upward in the figure. In order to appropriately reflect the infrared ray L, the inclination angle θ ₁ is preferably set to 30 to 40 °.

  The side surface of the recess 11 is composed only of the first side surface 11b and the second side surface 11c. For this reason, it is suitable for increasing the area of the first side surface 11b, and is advantageous for reflecting more infrared rays L upward in the drawing.

  In addition, according to the present embodiment, it is possible to reduce the size of the infrared data communication module A1. In general, the portion of the light emitting element 2 that actually emits light is a portion of about 1/3 that is closer to the upper side in FIG. Little light is emitted from the lower 2/3 portion of the light emitting element 2 in the figure. In the present embodiment, this lower 2/3 portion is surrounded by a cylindrical second side surface 11 c extending in the perpendicular direction N of the substrate 1. For this reason, for example, as in the example according to the prior art shown in FIG. 6, the concave portion 11 is planar by the amount of the first side surface 11 c compared to the concave portion 91 having the tapered side surface 91 b surrounding the lower end of the light emitting element 92. Visual dimension is reduced. Thereby, as shown in FIG. 2, the space of the recessed part 11 in the board | substrate 1 can be made small. Accordingly, the vertical dimension (width) of the substrate 1 in the drawing can be reduced, which is suitable for reducing the size of the infrared data communication module A1.

  Since the first side surface 11b is covered with the metal film 6, the first side surface 11b is a reflective surface having a relatively high reflectance. Such a reflective surface is suitable for suppressing attenuation when the infrared light L from the light emitting element 2 is reflected, and is suitable for increasing the emission efficiency of the infrared light L emitted from the light emitting element 2.

  3 to 5 show other embodiments of the infrared data communication module according to the present invention. In these drawings, elements similar to those in the above embodiment are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

  FIG. 3 shows a second embodiment of the infrared data communication module according to the present invention. The infrared data communication module A2 shown in the figure is different from the above-described embodiment in that the third side surface 11d is interposed between the first side surface 11b and the second side surface 11c. The third side surface 11 d is a ring-shaped curved surface that bulges toward the center of the recess 11. The third side surface 11d is connected to the first side surface 11b and the second side surface 11c in a geometrically continuous state.

  Also in such an embodiment, the infrared data communication module A2 can be reduced in size while appropriately reflecting the infrared ray L from the light emitting element 2 upward in the drawing. Further, when the infrared data communication module A2 is further reduced in size, the sizes of the light emitting element 2 and the recess 11 are further reduced. It may be more difficult to form the recess 11 so that the first side surface 11b and the second side surface 11c are directly connected to each other as the recess 11 becomes finer. According to the present embodiment, by providing the third side surface that is a curved surface, it is possible to expect an effect of relaxing the required accuracy for machining.

  FIG. 4 shows a third embodiment of an infrared data communication module according to the present invention. The infrared data communication module A3 shown in the figure is different from any of the above-described embodiments in that the first side surface 11b and the second side surface 11c are curved surfaces. The first side surface 11b and the second side surface 11c are an upper part and a lower part of a continuous curved surface, respectively. The angle of inclination of the curved surface with respect to the normal direction N of the substrate 1 decreases from the top to the bottom in the drawing. Thereby, the average inclination angle with respect to the perpendicular direction N of the second side surface 11c is set to be smaller than the average inclination angle of the first side surface 11b. Even in such an embodiment, the infrared data communication module A3 can be reduced in size while appropriately reflecting the infrared rays L from the light emitting elements 2 upward in the drawing.

FIG. 5 shows a fourth embodiment of an infrared data communication module according to the present invention. The infrared data communication module A4 shown in the figure is the same as the first embodiment described above in that the first side surface 11b and the second side surface 11c are directly connected, but the second side surface 11c is the substrate 1. It is different in that it is inclined with respect to the normal direction N. The inclination angle θ ₂ of the second side surface 11c is smaller than the inclination angle θ ₁ of the first side surface 11b. Also in such an embodiment, the infrared data communication module A4 can be reduced in size while appropriately reflecting the infrared rays L from the light emitting elements 2 upward in the drawing. Further, since the second side surface 11c has a shape opened upward in the drawing, the substrate 1 can be used in the bonding operation to the bottom surface 11a of the light emitting element 2 or the wire bonding operation to the upper surface of the light emitting element 2 in the drawing. Unfair interference can be avoided.

  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 recess is not limited to a circular cross section, and may be a polygonal cross section, for example. The light emitting element and the light receiving element are not limited to those capable of emitting or receiving infrared rays, and those capable of emitting or receiving visible light may be used. That is, the optical communication module is not limited to the infrared data communication module, and may be a communication system using visible light. Further, the optical communication module is not limited to a module capable of bidirectional communication, and may be a data transmission module including only a light emitting element.

It is sectional drawing which shows 1st Embodiment of the infrared data communication module which concerns on this invention. It is a principal part top view which shows 1st Embodiment of the infrared data communication module which concerns on this invention. It is principal part sectional drawing which shows 2nd Embodiment of the infrared data communication module which concerns on this invention. It is principal part sectional drawing which shows 3rd Embodiment of the infrared data communication module which concerns on this invention. It is principal part sectional drawing which shows 4th Embodiment of the infrared data communication module which concerns on this invention. It is principal part sectional drawing which shows an example of the conventional infrared data communication module.

Explanation of symbols

A1, A2, A3, A4 Infrared data communication module (optical communication module)
L Infrared N Normal direction θ ₁ , θ ₂ inclination angle of substrate 1 Substrate 2 Light emitting element 3 Light receiving element 4 Driving IC
5 Resin Package 6 Metal Film 7 Terminal 8 Wire 11 Recess 11a Bottom 11b First Side 11c Second Side 11d Third Side 12 Groove 51, 52 Lens Unit

Claims (5)

A substrate on which a recess opening on the surface is formed;
A light emitting device mounted on the bottom surface of the recess,
An optical communication module comprising:
The recess has a first side surface inclined so as to face the surface side with respect to the normal direction of the substrate, and is positioned closer to the bottom surface than the first side surface, and an inclination angle with respect to the normal direction of the substrate And a second side surface that is smaller than the first side surface. The first side surface is connected to the surface of the substrate, and the inclination angle with respect to the normal direction of the substrate is constant,
The optical communication module according to claim 1, wherein the second side surface has a cylindrical shape that is connected to the bottom surface and extends in a direction perpendicular to the substrate.   The optical communication module according to claim 2, wherein the first side surface and the second side surface are directly connected.   4. The optical communication module according to claim 2, wherein the first side surface has an inclination angle of 30 to 40 ° with respect to a normal direction of the substrate.   The optical communication module according to claim 1, further comprising a metal film covering at least the first side surface.

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