JPH08116087A - Optical module - Google Patents

Abstract

PURPOSE: To sufficiently suppress noise from the outside, noise generated by other functional elements, etc., by arranging a light emitting element, a light receiving element, etc., on one surface of an insulating board, and arranging a first and a second functional element groups on the other surface of the board. CONSTITUTION: A light receiving element 41, its first stage amplifier element 42 and a light emitting element 43 are mounted at least on one surface of an insulating board 1. A first reference potential region 10 is formed so as to correspond with a receiving circuit containing the light receiving element 41 and its first stage amplifier element 42. A second reference potential region 20 is formed as it remains electrically insulated from the first reference potential region 10, so as to correspond with a transmitting circuit part containing the light emitting element 43. A first functional element group constituting a receiving circuit part is mounted on the other surface of the insulating board 1. A second functional element group constituting a transmitting circuit part is mounted on the same surface, to constitute double-sided board mounting. Thereby external disturbance due to noise can be sufficiently suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical module used for an optical data link used in the optical communication field.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. 59-16389 discloses a bidirectional optical module having a light emitting element and a light receiving element, and as shown in FIG. A receiving circuit 102 including a light receiving element is optically separated by a spacer 103 and hermetically sealed.

[0003]

In an optical module that constitutes such an optical data link, it is extremely important in terms of performance to keep the receiving sensitivity of its receiving section high. It is necessary to suppress it as much as possible. This noise is mainly noise from the outside, noise from the drive circuit of the transmitter, noise from the comparator of the receiver, and the like. On the other hand, in the optical module of the type shown in FIG. 5, noise from the outside can be reduced, but measures against other noises have not been sufficient.

The present invention has been made to solve such a problem, and an object thereof is to provide an optical module capable of sufficiently suppressing disturbance due to noise.

[0005]

Therefore, an optical module according to the present invention is provided with a light receiving element on one surface side of an insulating substrate,
At least the first-stage amplification element and the light-emitting element are mounted, the first reference potential region is formed corresponding to the reception circuit section including the light-receiving element and the first-stage amplification element, and corresponds to the transmission circuit section including the light-emitting element. And the second reference potential region is electrically isolated from the first reference potential region. Then, the light receiving element and its first-stage amplifying element are covered with a conductive lid that is electrically connected to the first reference potential region and has a light transmitting portion at least at a portion corresponding to the light receiving element. Further, the first functional element group forming the receiving circuit section is mounted on the other surface side of the insulating substrate, and the second functional element group forming the transmitting circuit section is mounted on the same other surface side. Configure as an implementation.

[0006]

In the first reference potential region, the receiving circuit section is formed,
A transmission circuit unit is configured in the second reference potential region. Therefore, the transmission circuit unit and the reception circuit unit can be electrically separated, and G
Compared to the case where the reference potential region such as the ND pattern is common to the transmission / reception circuits, the noise sneaking into the other circuit unit is reduced.

Further, by covering the first-stage amplifying element and the light receiving element most susceptible to the noise with the conductive lid body connected to the first reference potential, the whole of these elements are electromagnetically shielded. Become.

Further, the first and second functional element groups, which are sources of noise, such as a comparator on the light receiving element side and a driving element on the light emitting element side, are opposite to the surface of the insulating substrate on which the first stage amplifying element and the like are mounted. Since it is mounted on the side surface, it is less likely to be affected by noise generated from these.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows an optical module according to this embodiment. In this optical module, a light receiving element 41 that transmits and receives an optical signal, a first stage amplification IC 42 that amplifies an output signal of the light receiving element 41, and an optical signal are emitted to one surface (hereinafter, referred to as “top surface” for convenience) of the ceramic substrate 1. The light emitting element 43 and the like for mounting the light emitting element 43 are mounted on the other surface (hereinafter, referred to as “bottom surface” for convenience) of the light emitting element 43.
A double-sided mounting type optical module in which elements such as 5 are mounted is configured.

Further, this optical module has a first ground pattern 10 and a second ground pattern 20 which are separated from each other with respect to the ceramic substrate 1.
A light receiving circuit including a light receiving element 41 is formed on the ground pattern 10 side, and a light emitting element 4 is formed on the second ground pattern 20 side.
3 constitutes an optical transmission circuit including 3.

The ground patterns 10 and 20 are formed on both surfaces of the ceramic substrate 1 via the through holes 11 and 21, and the wiring patterns 12 and 22 are formed on the ground patterns 10 and 20 via the insulating layer 30. Has formed,
The wiring patterns 12 and 22 are also through holes 13 and 23.
It is formed over both surfaces of the ceramic substrate 1 via.

The light receiving element 41 and the first-stage amplification IC 42 are covered with a conductive lid (lid body) 51 formed of metal or conductive plastic, and the outer edge portion of the lid 51 is For the first ground pattern 10 exposed on the ceramic substrate 1, Au
-Fixed with Sn solder. With such a configuration, the light receiving element 41 and the first-stage amplification IC 42 are
Since it is sealed by the conductor connected to the ND level, these elements most susceptible to noise are electromagnetically shielded.

The light emitting element 43 on the upper surface side adjacent to the light receiving element 41 uses a transparent lid 53 to prevent the emitted optical signal from being blocked, and the transmitting / receiving circuit mounted on the lower surface side. Each part is sealed on the ceramic substrate 1 by potting a resin using a single lid 54. The lids 53 and 54 may be made of a conductive material. In this case, as shown in FIG.
Use 20 to fix. Further, when the lid 53 is made of an opaque material, it is necessary to form an opening window for transmitting an optical signal at a portion corresponding to the light emitting element 43.

As shown in FIG. 2, the appearance of the optical module thus constructed is such that the upper surface and the lower surface of the ceramic substrate 1 are sealed by lids 51, 53 and 54, respectively. Thereafter, as shown in FIG. 3, each lead pin 55 is attached to one long side portion of the ceramic substrate 1. Each lead pin 55 is fitted to the end portion of the substrate in the form of an edge clip, and is electrically connected to the optical transmitting circuit and the optical receiving circuit. In addition, this optical module includes a lens 6
1, the sleeve 62 and the receptacle 63 are arranged on one end surface of a package 60 which is integrated, and then the package 6
A bidirectional optical data link module is configured by attaching the back cover 64 to one end surface of the 0.

Further, in the optical module shown in FIG. 1 and the like, the example in which the lower surface side is also sealed with the lid 54 is shown, but it is also possible to seal the element mounted on the lower surface side by potting the resin 70. is there. Although this type is illustrated in FIG. 4, the basic configuration is the same as that of the optical module in FIG. 1, and a description thereof will be omitted.

Further, in the above-described embodiment, the lid 51
The example in which is fixed to the first ground pattern 10 with Au—Sn solder is illustrated, but the present invention is not limited to this example. For example, by die-bonding with a conductive resin, It can also be fixed. Further, although the glass window is illustrated as a member that transmits light to the light receiving element, a plastic lid coated with a transparent conductive film (ITO) or the like may be used instead.

As described above, the optical module illustrated in this embodiment can suppress the influence of noise as described above, and mount each element on both sides of the substrate while considering the characteristics of each element. Since the configuration described above is adopted, it is possible to improve the mounting density of components and further reduce the size of the optical module itself. As a result, it is possible to contribute to the reduction of the number of parts and the machining process, and to reduce the cost.

[0018]

As described above, in the optical module according to the present invention, the light emitting element, the light receiving element, and the like are arranged on one surface of the insulating substrate, and the first and the first elements including the element serving as the noise source are provided. The bifunctional element group is arranged on the other surface of the insulating substrate, and the reference potential area (first reference potential area) of the receiving side circuit is provided.
And a reference potential region (second reference potential region) of the transmission side circuit are separated from each other, and a first-stage amplification element which is most susceptible to noise is covered with a conductive lid.

Therefore, the first-stage amplifying element and the like can be electromagnetically shielded sufficiently, and noises coming from the outside, noises generated in other functional elements, and noises sneaking from the reference potential such as GND are eliminated. It becomes possible to suppress sufficiently.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an optical module according to an embodiment.

FIG. 2 is a perspective view showing an appearance of the optical module shown in FIG.

FIG. 3 is a diagram showing a configuration of the optical module of FIG.
FIG. 6 is an exploded perspective view showing a state of being integrated with a package.

FIG. 4 is a vertical sectional view showing another embodiment of the optical module.

FIG. 5 is a sectional view showing a configuration of a conventional optical module.

[Explanation of symbols]

1 ... Ceramic substrate, 10 ... First ground pattern, 2
0 ... Second ground pattern, 11, 21 ... Through hole (for ground pattern), 12, 22 ... Wiring pattern,
13, 23 ... Through hole (for wiring pattern), 30 ...
Insulating layer, 41 ... Light receiving element, 42 ... First stage amplification IC, 43 ...
Light emitting element, 44 ... Comparator, 45 ... Driving IC, 5
1, 53, 54 ... Lid, 52 ... Glass window.

Claims (3)

[Claims] 1. A light-receiving element mounted on one surface side of an insulating substrate, a first-stage amplifying element and a light-emitting element thereof, and a receiving circuit portion including the light-receiving element and the first-stage amplifying element, which are formed on the insulating substrate. A first reference potential region, and a second reference potential region which is electrically insulated from the first reference potential region and which corresponds to the transmission circuit section including the light emitting element and is formed on the insulating substrate, A conductive lid that is electrically connected to the first reference potential region, covers the light receiving element and its first-stage amplification element, and has a light transmitting portion at least at a portion corresponding to the light receiving element; Functional element group which is mounted on the other surface side of the insulating substrate and constitutes the receiving circuit section, and a second functional element which is mounted on the other surface side of the insulating substrate and constitutes the transmitting circuit section And an optical module comprising . 2. The optical module according to claim 1, wherein the first functional element group includes a comparator to which a signal is given from the first-stage amplification element. 3. The optical module according to claim 1, wherein the second functional element group includes a drive IC that drives the light emitting element.