JP2001015793A - Optical transmission/reception module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical transmission/reception module which has a simple construction capable of realizing high frequency shielding between a transmission circuit and a reception circuit. SOLUTION: An optical transmission module 11, which has a semiconductor light emitting device and an optical fiber 15 connected optically to the semiconductor device, an light receiving module 12 which has a photodetector and an optical fiber 16 connected optically to the photodetector, a circuit board 1 with a transmission circuit 3 which is mounted on its upper surface and supplies a drive signal to the light emitting device, a receiving circuit 4 which is mounted on its lower surface and processes a current signal supplied from the photodetector, a ground electrode 7 formed on its side surface and a plurality of wiring layers formed in it and metal packages 21a and 21b, in which the circuit board 1 is housed and fixed and the optical transmission module 11 and the light receiving module 12 are fixed are provided. A central wiring layer 6 of the wiring board 1 is used as a ground wiring layer, which is connected to the package via the ground electrode 7 and is grounded so as to realize high-frequency shielding between the upper and lower surfaces of the circuit board 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transmission / reception module used for an optical communication system and the like.
The present invention relates to a high-speed optical transmission / reception module having a transmission speed of s or more.

[0002]

2. Description of the Related Art An optical transmitter / receiver module includes a transmitting circuit and a receiving circuit integrally housed in the same package, and communicates by an optical signal via an optical transmitting module and an optical transmitting / receiving module connected to these circuits. Is an optical transmission device that performs the following. In such an integrated optical transmission / reception module, the transmission circuit processes a transmission signal with a large amplitude, while the reception circuit processes a reception signal with a small amplitude. Receive interference from As a result, an error occurs in the received signal, so that the reliability of the transmission characteristics is impaired. Therefore, in the case of an integrated optical transceiver module, it is necessary to shield the transmission circuit and the reception circuit at a high frequency.

[0003] An example of a conventional optical transceiver module will be described with reference to FIG. In the following drawings, the same portions are denoted by the same reference numerals and description thereof will be omitted.

The optical transceiver module 50 shown in FIG. 4 comprises a circuit board 51, a laser diode module 11, a photodiode module 12, and metal packages 58a and 58.
8b. A ground pattern 2 for shielding high frequency is provided at the center of the circuit board 51, and is formed over the front and back of the board via through holes. Metal plates 55a and 55b connected to this ground pattern for shielding high frequencies are provided so as to protrude upward and downward from the substrate. The surface area of the circuit board 51 is divided into two by these ground patterns and the metal plates 55a and 55b, and a transmission circuit 54 is formed on the front and back sides on the back side in FIG.
3 are formed.

[0005] In the laser diode module 11, a laser diode (not shown) and an optical fiber 15 are optically coupled and hermetically sealed, and connected to a transmission circuit 53.

[0006] The photodiode module 12 has a photodiode (not shown) and an optical fiber 16 optically coupled and hermetically sealed, and is connected to a receiving circuit 54.

The circuit board 51, the laser diode module 11, and the photodiode module 12 are housed in metal packages 58a, 58b. At this time, the metal plate 5
The metal packages 5a and 55b are electrically connected to the metal packages 58a and 58b, respectively, whereby high-frequency shielding between the transmission circuit 53 and the reception circuit 54 is achieved.

[0008]

However, in the conventional example shown in FIG. 4, since a metal plate is used to shield high frequencies, the area on the substrate is divided into two by a ground pattern, and the transmission circuit and the reception circuit are formed. Must be formed on each of the front and back sides of a substantially half portion of the substrate, and the structure of the module becomes complicated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an optical transceiver module which can achieve high-frequency cutoff between a transmission circuit and a reception circuit with a simple configuration.

[0010]

The present invention solves the above-mentioned problems by the following means.

That is, an optical transmitting / receiving module according to the present invention is an optical transmitting module having a semiconductor light emitting element, a first optical fiber optically coupled to the semiconductor light emitting element, a light receiving element, and a light receiving element. A light receiving module having a second optical fiber optically coupled to the substrate, a substrate having an external electrode formed on a side surface formed of an insulating material, and a plurality of wiring layers formed therein; A transmission circuit formed on one of the upper surface or the lower surface of the substrate and connected to the semiconductor light emitting element and supplying a drive signal to the semiconductor light emitting element; and a transmission circuit formed on the other surface of the substrate in a front-to-back relationship with the one surface. A receiving circuit that is connected to the light receiving element and receives a current signal from the light receiving element and processes the current signal; And a package fixing the light receiving module and the light receiving module, wherein the wiring layer includes a ground wiring layer connected to the external electrode and connected to the package via the external electrode. .

It is preferable that a distance from the ground wiring layer to the one surface of the substrate is substantially equal to a distance from the ground wiring layer to the other surface of the substrate.

The external electrode may be formed so as to cover substantially the entire side surface of the substrate. Further, the substrate can be constituted by a ceramic substrate.

In the above-mentioned optical transmitting and receiving module, the substrate is a glass epoxy substrate having a through-hole having a metal conductor formed on an inner wall, and the through-hole at a peripheral portion of the substrate is perpendicular to the upper surface. It is preferable that the metal conductor exposed on the side surface of the substrate by being cut form the external electrode.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Some embodiments of the present invention will be described below with reference to the drawings.

(1) First Embodiment FIG. 1 is an exploded perspective view showing a first embodiment of an optical transceiver module according to the present invention, and FIG.
FIG. 4 is an explanatory diagram showing details of a side ground electrode of the optical transceiver module shown in FIG. As shown in both figures, the feature of the optical transceiver module of the present embodiment lies in the form of ground connection for shielding interference by high-frequency signals.

A schematic configuration of the optical transceiver module of the present embodiment will be described with reference to FIG. The optical transmitting / receiving module 10 shown in FIG. 1 includes a circuit board 1 characteristic of the present invention, metal packages 21a and 21b, and a laser diode module 11 and a photodiode module 12 similar to the conventional example.

The circuit board 1 is formed of ceramic and has a plurality of wiring layers inside. On the side surface of the circuit board 1, the external electrodes 7 are formed on almost the entire surface. Among the wiring layers of the circuit board 1, the central wiring layer 6 is connected to the external electrodes 7 on the side surfaces of the circuit board 1, as shown in FIG.

Returning to FIG. 1, a transmitting circuit 3 and a receiving circuit 4 are mounted on the upper and lower surfaces of the circuit board 1, respectively. The transmission circuit 3 includes, for example, a laser diode driver IC, and receives an input of an electric signal of a predetermined logic level and converts it into a drive current of a laser diode. The receiving circuit 4 includes, for example, a signal processing circuit. The receiving circuit 4 receives a current signal generated according to an optical signal incident on the photodiode, performs voltage conversion processing, amplification processing, and waveform shaping processing, and extracts the signal. An electrical signal of a predetermined logic level is output in synchronization with the clock.

The laser diode module 11 in which a laser diode (not shown) and an optical fiber 15 are optically coupled, is electrically connected to the transmission circuit 3 via an electrode lead 13. Also, a photodiode (not shown)
The photodiode module 12 in which the optical fiber 16 and the optical fiber 16 are optically coupled is electrically connected to the receiving circuit 4 via the electrode lead 14.

The circuit board 1, the laser diode module 11 and the photodiode module 12 are housed in metal packages 21a and 21b. Here, the inner size of the metal packages 21a and 21b and the outer size of the circuit board 1 (including the external electrode 7) are selected so that they can be joined to each other. Based on this correspondence, the circuit board 1 and the metal packages 21a and 21b are connected and fixed to each other, whereby the central wiring layer 6 forms the ground wiring layer 6, and the external electrodes 7 on the side surfaces of the circuit board 1 The side ground electrode 7 is formed. In connecting and fixing the circuit board 1 and the metal packages 21a and 21b,
A conductive adhesive or the like may be interposed.

As described above, in the optical transceiver module 10 of the present embodiment, the central layer of the internal wiring layer of the circuit board 1 is used as the ground wiring layer 6, and the metal package is provided via the side ground electrode (external electrode) 7 on the side of the board. Since they are electrically connected to the circuit boards 21a and 21b, interference by high-frequency signals can be shielded on both sides of the circuit board 1. This provides an optical transceiver module having a simple configuration, excellent transmission characteristics, and a small mounting area.

(2) Second Embodiment Next, a second embodiment of the optical transceiver module according to the present invention will be described with reference to FIG. The feature of the optical transceiver module 30 of the present embodiment lies in the configuration of the circuit board and its external electrodes. The other points are substantially the same as those of the optical transmitting / receiving module 10 shown in FIG.

FIG. 3 is an explanatory diagram showing a main part of the circuit board 31 of the optical transceiver module 30 of the present embodiment. The circuit board 31 is formed of a glass epoxy board having a multilayer wiring, and a wiring layer at the center of the internal wiring layers forms a ground wiring layer 32. At least a peripheral portion of the circuit board 31 is provided with a through hole 37 in which a conductor made of metal is formed on an inner wall,
The ground wiring layer 32 is connected to the conductor of the through hole 37 at the peripheral portion. Ground electrode 33 on the side of substrate
Can be formed simply by cutting the circuit board 31 in a direction perpendicular to the upper surface so that the metal conductor in the through hole 37 at the peripheral edge of the board is exposed. In the present embodiment, connection and fixation with the metal packages 21a and 21b can be realized by interposing a conductive adhesive or the like.

[0025]

As described in detail above, the present invention has the following effects.

That is, according to the optical transceiver module of the present invention, the ground wiring layer at the center inside the substrate is grounded to the metal package via the external electrodes formed on the side surfaces of the substrate. It can be shielded on both sides of the circuit board. Thus, the transmission circuit can be formed on one of the upper surface and the lower surface of the circuit board, and on the other hand, the reception circuit can be formed on the other surface that has a front and back relationship with the one surface on which the transmission circuit is formed. Provided is an optical transmitting and receiving module having excellent transmission characteristics and a small mounting area.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a first embodiment of an optical transceiver module according to the present invention.

FIG. 2 is an explanatory diagram showing details of a side ground electrode of the optical transceiver module shown in FIG. 1;

FIG. 3 is an explanatory diagram illustrating a main part of a second embodiment of the optical transceiver module according to the present invention.

FIG. 4 is an exploded perspective view showing an example of a conventional optical transceiver module.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 31 Circuit board 3 Transmitting circuit 4 Receiving circuit 6, 36 Ground wiring layer 7 Side ground electrode (external electrode) 11 Laser diode module 12 Photodiode module 21a, 21b Metal package 37 Through hole

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // H05K 9/00 H01L 31/02 CF term (Reference) 5E321 AA02 AA14 AA17 GG01 GG05 5F041 EE01 FF14 5F073 AB21 AB28 BA02 EA29 FA06 5F088 AA01 BA02 BA03 BA15 BB01 EA09 EA16 EA20 JA14 JA20 5F089 AA01 AC10 AC17 AC20

Claims (5)

[Claims] An optical transmission module having a semiconductor light emitting element, a first optical fiber optically coupled to the semiconductor light emitting element, a light receiving element, and a second optically coupled to the light receiving element. An optical receiving module having an optical fiber, and an external electrode formed of an insulating material and formed on a side surface,
A substrate having a plurality of wiring layers formed therein; and a transmission circuit formed on one of the upper surface and the lower surface of the substrate and connected to the semiconductor light emitting element to supply a drive signal to the semiconductor light emitting element Formed on the other side of the substrate in a front-to-back relationship with the one side,
A receiving circuit connected to the light receiving element and receiving a current signal from the light receiving element to process the current signal; formed of a conductive material, accommodating and fixing the substrate therein, the light transmitting module and the light A light receiving module comprising: a package for fixing a receiving module; wherein the wiring layer includes a ground wiring layer connected to the external electrode and connected to the package via the external electrode. 2. The optical transceiver module according to claim 1, wherein a distance from the ground wiring layer to the one surface of the substrate is substantially equal to a distance from the ground wiring layer to the other surface of the substrate. . 3. The optical transceiver module according to claim 1, wherein said external electrode is formed so as to cover substantially the entire side surface of said substrate. 4. The optical transceiver module according to claim 1, wherein said substrate is a ceramic substrate. 5. The substrate is a glass epoxy substrate having a through hole in which a metal conductor is formed on an inner wall, and the external electrode is formed by cutting a through hole in a peripheral portion of the substrate in a direction perpendicular to the upper surface. The optical transceiver module according to claim 1, wherein the optical transceiver module is a metal conductor exposed on a side surface of the substrate.