JP2526493B2 - Structure of light receiving module - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in the structure of a light receiving module of an optical receiver used for optical communication and the like.

[0002]

2. Description of the Related Art Conventionally, this type of light receiving module is roughly divided into an avalanche photodiode element (ADP element) 101, a preamplifier integrated circuit chip (preamplifier AmpIC chip) 103, as shown in FIG. In general, the package 105, the glass 107, and the frame ground chassis 109 are provided. Here, the package 105 is formed of a metal in a hollow cylindrical shape, and has a structure in which one end face in the axial direction is closed. The package 105 accommodates an ADP element 101 that performs photoelectric conversion and a front-end AmpIC chip 103 mounted on the case ground of the package 105 via a microchip capacitor 111. The ADP element 101 and the front AmpIC chip 103 are connected by a bonding wire 113. Also, package 1
Glass 107 is disposed on the other axial end surface of 05. The lead terminal 11 is provided on one end surface side of the package 105.
5 are provided. And this light receiving module
With the package 105 fitted to the chassis 109,
An optical fiber 117 is formed on the surface of the glass 107 of the light receiving module.
Is used by placing.

The light receiving module is a front AmpIC.
When the sub on the back surface of the chip 103 is electrically connected to the negative power source, it is grounded in an alternating manner via the microchip capacitor 111.

[0004]

By the way, in the conventional light receiving module, the microchip capacitor 11 is used.
Since the pre-Amp IC chip 103 is mounted after mounting No. 1, the pre-Am in the next process depends on the mounting accuracy (position, horizontality) of the microchip capacitor 111.
The work time of the mounting process of the pIC chip 103 is greatly affected. In particular, if the levelness of the microchip capacitor cannot be ensured, the wire bonding work may be hindered.

Therefore, an object of the present invention is to provide a structure of a light receiving module which can reduce the working time of the mounting process.

[0006]

The structure of a light receiving module according to claim 1 is a metallic coaxial housing containing an avalanche photodiode element for photoelectric conversion and a preamplifier integrated circuit chip for amplifying an electric signal from this element. In a light receiving module including a mold package, a glass provided on an end face in the axial direction of the package, and a chassis for a frame ground that accommodates the package, the back side of the preamplifier integrated circuit chip is placed in conduction with the package. Further, it is characterized in that it is arranged in the frame ground chassis with a floating ceramic ring interposed around the package.

That is, in the structure of the light receiving module according to the first aspect, the package is arranged in the chassis for frame ground through the insulator, so that the package and the chassis are electrically insulated from each other, and the package and the chassis are electrically separated from each other. Since it is grounded in an alternating current by the electrostatic capacitance generated during the period, the microchip capacitor becomes unnecessary when the preamplifier integrated circuit chip is arranged in the package. Therefore, the step of mounting the microchip capacitor becomes unnecessary, and the difficulty of mounting the preamplifier integrated circuit chip in the next step due to the mounting accuracy of the microchip capacitor is eliminated.

According to the second aspect of the present invention, a metal land having a constant height is formed from the bottom of the package, and the preamplifier integrated circuit chip can be arranged on the metal land.

That is, according to the package of the second aspect, a land having a constant height is formed from the bottom of the package, and the preamplifier integrated circuit chip is mounted on this land, whereby the mounting height of the avalanche photodiode element is increased. Almost identical, which simplifies the work of bonding wires.

According to a third aspect of the present invention, the insulator is composed of a ceramic ring.

That is, since the insulator according to claim 3 is composed of the ceramic ring, the package and the chassis can be securely fixed to each other.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to embodiments.

FIG. 1 is a sectional view showing an embodiment of the structure of the light receiving module of the present invention. The structure of the light receiving module shown in this figure is roughly divided into the ADP element 1 and the front Am.
It is generally provided with a pIC chip 3, a package 5, a glass 7, a frame ground chassis 9, and an insulating ceramic ring 10.

Explaining the structure in more detail, the package 5 is made of metal in the shape of a hollow cylinder and has a structure in which one end face in the axial direction is closed. The package 5 is provided with a land 11 having a constant height from the bottom thereof and having an area slightly larger than the projected area of the front AmpIC chip 3. The height of the land 11 is the front Am
The mounting height of the ADP element 1 and the mounting height of the front AmpIC chip 3 are selected to be substantially the same when the pIC chip 3 is mounted.

The package 5 includes ADP for photoelectric conversion.
The element 1 is mounted, and the front AmpIC chip 3 is mounted and housed on the land 11. After being mounted in this way, the ADP element 1 and the front AmpIC chip 3 are mounted.
And are connected by a bonding wire 13. A glass 7 is arranged on the other axial end surface of the package 5. Lead terminals 15 are provided on one end surface side of the package 5. Then, this light receiving module is completed by fitting the package 5 into the chassis 9 via the insulating ceramine ring 10. In the structure of the light receiving module, it is used by disposing the optical fiber 17 on the surface of the glass 7.

The operation of such a light receiving module will be briefly described. The optical signal output from the optical fiber 17 passes through the upper surface glass 7 of the coaxial metal package 5 and the ADP.
Reach element 1. The received optical signal is converted into an electric signal by the ADP element 1. The electric signal is input to the front AmpIC chip 3 via the bonding wire 13. The electric signal is amplified by the pre-Amp IC chip 3 and transmitted to the circuit of the next stage via the lead terminal 15.

Next, the operation of the structure of the light receiving module will be described. The sub on the back surface of the front AmpIC chip 3 is electrically connected to the case of the package 5. Where the preamp AmpI
It is assumed that the C chip 3 is used as a negative power source and that the sub on the back surface thereof is electrically connected to the negative power source. Further, the metal package 5 is also charged with a negative power source.

On the other hand, the outer periphery of the metal package 5 is in contact with and covered with the inner peripheral surface of the ceramine cling 10.
Further, the outer circumference of the ceramine cling 10 is in contact with the frame ground metal chassis 9. Therefore, since the ceramine cling 10 is mechanically contacted and fixed between the metal package 5 charged with the negative power source and the frame ground chassis 9, it is possible to form a capacitor for AC grounding. become.

Therefore, although the capacitor formed between the metal package 5 and the metal frame ground chassis 9 is grounded in an AC manner, it is in an insulated state in a DC manner. As a result, it is possible to omit the microchip capacitor conventionally required when mounting the front AmpIC chip 3 on the package 5, and to mount the front AmpI of the next process with the mounting accuracy of the microchip capacitor.
It means that the work of mounting the C chip will not be difficult.

It goes without saying that the present invention can be applied to other light receiving elements such as PIN photodiodes.

[0021]

As described above, according to the structure of the light receiving module according to the first aspect of the invention, the front AmpIC chip is directly mounted on the package, so that it is not necessary to mount the microchip capacitor as in the conventional case. Thus, there is an effect that the mounting work of the front AmpIC chip is simplified and the cost can be reduced.

According to the second aspect of the present invention, the front AmpI is provided on the land formed at a constant height from the bottom of the package.
Since the C chip is mounted, the bonding wire work is simplified.

According to the third aspect of the invention, since the ceramic ring is interposed between the package and the chassis for frame ground, the package and the chassis can be securely fixed, and the capacitor can be provided between the package and the chassis. The effect is that it can be formed and grounded in an alternating current.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the structure of a light receiving module of the present invention.

FIG. 2 is a sectional view showing a structure of a conventional light receiving module.

[Explanation of symbols]

 1 ADP element 3 Front AmpIC chip 5 Package 7 Glass 9 Chassis for frame ground 10 Ceramink ring 11 Land 13 Bonding wire 15 Lead terminal 17 Optical fiber

Claims (3)

(57) [Claims] 1. A metal coaxial package containing an avalanche photodiode element for photoelectric conversion and a preamplifier integrated circuit chip for amplifying an electric signal from the element, and a glass provided on an axial end surface of the package. In a light-receiving module equipped with a frame ground chassis for housing this package, the back side of the preamplifier integrated circuit chip is placed in conduction with the package, and an insulator is placed around the package for the frame ground. The structure of the light receiving module, which is characterized by being placed in the chassis. 2. The package has a structure in which a metal land having a constant height is formed from a bottom of the package, and the preamplifier integrated circuit chip can be arranged on the metal land. 1. The structure of the light receiving module described in 1. 3. The structure of the light receiving module according to claim 1, wherein the insulator is a ceramic ring.