JPH0422908A - Optical module - Google Patents

Abstract

PURPOSE:To improve rapid operation without deteriorating optical characteristics by partially through-welding an optical base mounted on a step difference part from the bottom plate of a package and fixing the base on the step difference part. CONSTITUTION:The step difference part 14 having depth approximately equal to the thickness of the metallic optical base 22 is formed on the bottom plate of the metallic package 12 and the optical base 22 mounted on the step difference part 14 is partially through-welded and the bottom plate side of the package 12 and fixed on the step difference part 14. Preferably, the through-welding is attained by laser-welding the approximately center part of the edge part of the base 22. Consequently, an optical module capable of suppressing the deterioration of optical characteristics such as optical coupling efficiency and adaptive for rapid operation can be obtained.

Description

[Detailed Description of the Invention] Overview Regarding an optical module in which an optical substrate on which an optical component including an optical semiconductor element is mounted is housed in a package, optical characteristics such as optical coupling efficiency are not deteriorated during manufacturing or use. <, and for the purpose of providing an optical module suitable for high-speed operation, a step portion having a depth approximately equal to the thickness of the metal optical substrate is formed on the bottom plate of the metal package, and the optical module is seated on the step portion. The above-mentioned optical substrate is fixed to the stepped portion by partially penetration welding from the bottom plate side of the package.

INDUSTRIAL APPLICATION FIELD The present invention relates to an optical module in which an optical substrate on which an optical component including an optical semiconductor element is mounted is housed in a package.

Components include optical components such as LD collimators and PD collimators, which are equipped with light-emitting optical semiconductor elements such as LDs (semiconductor lasers) and LEDs (light-emitting diodes), or light-receiving optical semiconductor elements such as PDs (photodiodes). In recent years, paired-chip type optical semiconductor devices with excellent high-speed operation have become widely used in optical modules, so the optical substrate on which the above-mentioned optical components are mounted is housed in a package, and the package is hermetically sealed. It is customary to do so.

In this type of optical module, deformation of the optical R-plate directly affects optical characteristics such as optical coupling efficiency.
It is required that the optical substrate is not deformed even slightly when manufacturing or using the optical module. Furthermore, with the aim of ensuring high-speed operation characteristics of optical modules, improvements are being sought in the impedance characteristics and the like of electrical connections of optical semiconductor elements.

BACKGROUND ART FIG. 5 shows a plan view (a), a front view (b), and a side view (C) of a package used in a conventional optical module.

This package 2 is formed by pressing a metal plate, for example, and has lead terminals 6 erected on its bottom plate 4 to be connected to signal lines and ground lines.

Further, a flange 8 is formed at the upper end of the package 2, and an airtight seal is achieved by fixing a lid member (not shown) to the flange 8 by projection welding or the like. The optical substrate 10 on which the optical components are mounted is fixed entirely on the flat surface of the bottom plate 4 of the package, for example, by soldering.

Problems to be Solved by the Invention In conventional optical modules, the optical board on which optical components are mounted was fixed entirely to the bottom plate of the package.
When the lid member is welded to the package flange during the manufacture of optical modules, if the bottom plate of the package is bent or otherwise deformed, the optical board will also be deformed accordingly, making it difficult to adjust it to the best possible position before attaching the lid member. Optical characteristics such as optical coupling efficiency sometimes deteriorated. In addition, when using this optical module, it is customary to mount this optical module on a printed wiring board together with electronic circuit components in the form of lead components. In some cases, the bottom plate of the lens was deformed and the optical characteristics deteriorated in the same way.

On the other hand, in conventional optical modules, the electrical connection of the electrical output terminal or electrical input terminal of the optical component mounted on the optical board to the lead terminal of the package is usually made using a bonding wire. In this case, a bonding wire that is long enough to correspond to the thickness of the optical board mounted on the bottom plate of the package is required, which deteriorates the impedance characteristics of the connection part and may impede high-speed operation characteristics. There was also the problem.

The present invention was created in view of these circumstances, and aims to provide an optical module that does not cause deterioration of optical characteristics such as optical coupling efficiency during manufacture or use and is suitable for high-speed operation.

Means for Solving the Problems The above-mentioned technical problem is that in an optical module in which an optical substrate on which an optical component including an optical semiconductor element is mounted is housed in a package, a metal base plate is attached to the bottom plate of the metal package. By forming a stepped portion having a depth approximately equal to the thickness of the optical substrate, and fixing the optical substrate seated on the stepped portion to the stepped portion by partially penetration welding from the bottom plate side of the package. resolved.

Effect According to the above configuration, the package and the optical board are made of metal, and the optical board is seated on the stepped portion formed on the bottom plate of the package and has a depth approximately equal to the thickness of the optical board, so that the electrical input of the optical component is reduced. The length of the bonding wire used to connect the terminal or electrical output terminal to the lead terminal of the package can be reduced by an amount equivalent to the thickness of the optical board, improving the impedance characteristics of the connection part and improving high-speed operation characteristics. It becomes easier to secure. In addition, the optical board seated on the stepped portion is partially penetrate-welded from the bottom plate side of the package, so even if the bottom plate of the package bends or deforms, it will not be caused by the deformation of the package. The optical board is not easily deformed. As a result, optical properties such as optical coupling efficiency are less likely to deteriorate during manufacturing or use of the module.

Example Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a longitudinal cross-sectional view of an optical module showing an embodiment of the present invention, FIG. 2 is a cross-sectional view of the same module, FIG. 4 is a bottom view of the same module, and FIG. 3 is the same before attaching the lid member. FIG. 3 is a plan view of the module.

A stepped portion 14 is formed on the bottom plate of the metal package 12 made of SUS material or the like by pressing or the like.
Inside the stepped portion 14 of the bottom plate, there is also a stud 16 (shown in FIG. 4) that protrudes downward from the bottom plate by press working.
is formed.

On the outside of the stepped portion 14 of the bottom plate of the package, there is an IJ-upper terminal 18 to which signal lines, ground lines, power lines, etc. are connected.
is erected. Lead terminals to which signal lines and power lines are connected are erected on the package through an insulator such as glass, and lead terminals to which a ground wire is connected are erected directly on the package. Since the length of the portion of the lead terminal 18 protruding into the package is minute, this portion is not shown.

20 is an electric board on which an electronic circuit component 24 such as an LSI is mounted, for example, by surface mounting, and 22 is an optical board on which optical components are mounted. The electrical board 20 is made of an insulator such as ceramics, and the optical board 22 is made of a metal material such as SUS material. The electrical board 20 and the optical board 22 are joined together, for example by brazing, and seated on the stepped portion 14 of the package.

Since the depth of the stepped portion 14 is approximately equal to the thickness of the electrical board 20 and the optical board 22, the upper surfaces of the electrical board 20 and the optical board 22 are approximately flush with the flat surface of the portion of the bottom plate of the package where the stepped portion is not formed. to do.

The electrical board 20 and the optical board 22 seated on the stepped portion 14 are welded to the package 12 by performing penetration welding by laser welding or the like to the optical board 22 from the back side of the package at welding points A and Δ4 shown in FIG. Fixed. That is, by partially fixing the optical board 22 of the integrated electrical board 20 and optical board 22 to the package 12, the contents of the package are fixed. Welding point A+, A2 and welding point A
! , A4 are two points that are close to each other and correspond to portions located approximately in the center of the edge of the optical substrate 22 that contacts the stepped portion 14 . When the optical substrate 22 seated on the stepped portion 14 is partially penetrate-welded in this way, even if the package 12 is undesirably deformed, the optical substrate 22
Since it is difficult to deform, there is little deterioration of optical properties. Penetration welding can be performed by YAG laser welding. When an optical board is fixed to a package by this type of rail welding, the fixing work can be automated more easily than when it is fixed by soldering or U3 attachment. In this embodiment, the reason why the package 12 and the optical board 22 are made of a metal material such as SUS material is because it allows for good heat concentration during the laser welding and enables efficient welding with less deformation. This is to do so.

The configuration and operation of the optical circuit realized on the optical substrate 22 will be explained. 26 is a common fiber collimator fixed on the optical board 22, and this member is the optical fiber 28
and a condensing and collimating lens (not shown) are held in a predetermined positional relationship. The original fiber 28 is introduced into the package from the outside through a fiber introduction hole formed in the side wall of the package 12, and the introduction hole is hermetically sealed with solder or the like. 30 is an optical filter formed by forming a filter film such as a dielectric multilayer film on a glass substrate, and this optical filter 30 is fixed at a predetermined position on the optical substrate 22. 32 is a P fixed on the optical substrate 22.
It is a D collimator and is constructed by holding a photodiode and a condensing lens in a predetermined positional relationship. 34
is an LD collimator fixed on the optical board 22,
It is constructed by holding a semiconductor laser and a collimating lens in a predetermined positional relationship.

In this embodiment, the optical modineer functions as an optical transceiver for bidirectional wavelength division multiplexing transmission.

The light of a predetermined wavelength transmitted by the optical fiber 28 is
The light passes through the optical filter 30 and is converted into an electrical signal by the PD collimator 32, and this signal is amplified by an amplifier configured on the electrical board 20 and output to the outside via a lead terminal. On the other hand, the input terminal of the LD collimator 34 is connected to the lead terminal 18 of the package by a bonding wire or the like directly or via a pad on the optical board, and the transmitted light is transmitted based on the drive signal input via the lead terminal 18. The light is emitted from the LD collimator 34. The wavelength of the transmitted light is set to a different wavelength from that of the received light. The light emitted from the LD collimator 34 is reflected by the optical filter 30 and introduced into the optical fiber 28,
The light is output from this optical module.

As described above, when the input terminal of the LD collimator 34 and the lead terminal 18 of the package are connected by bonding wires, high-speed characteristics etc. are deteriorated when using the conventional technique. On the other hand, in the case of this embodiment, since the optical board 22 is seated on the stepped portion 171, the length of the bonding wire for wire bonding connection can be shortened, and the deterioration of high-speed operation characteristics can be reduced. I can do it. Also, especially when looking at the ground wire, it is possible to strengthen the grounding of the part that should be grounded, which improves the crosstalk characteristics. In this embodiment, not only the optical board 22 (but also the electrical board 20 is seated on the stepped portion 14,
Deterioration of high-speed characteristics on the receiving side is also prevented.

As described in detail, the present invention has the advantage that it is possible to provide an optical module whose optical characteristics such as optical coupling efficiency are unlikely to deteriorate during manufacture or use and which is suitable for high-speed operation.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view of an optical module showing an embodiment of the present invention, Fig. 2 is a cross-sectional view of the optical module, Fig. 3 is a plan view of the same module with the lid removed, and Fig. 4 is a longitudinal cross-sectional view of the optical module. FIG. 5 is a plan view (a), a front view (b), and a side view (C) of a package used in a conventional optical module. 12... Package, 14... Step portion, 20... Electrical board, 22... Optical board.

Claims (1)

[Claims] 1. In an optical module in which an optical board on which an optical component including an optical semiconductor element is mounted is housed in a package, the optical board made of metal is mounted on the bottom plate of the package (12) made of metal. (22) The stepped portion (1
4), and the optical substrate (22) seated on the stepped portion (14) is fixed to the stepped portion (14) by partially penetration welding from the bottom plate side of the package (12). An optical module featuring: 2. The optical module according to claim 1, wherein the penetration welding is performed by laser welding approximately the center of the edge of the optical substrate (22). 3. Claim 1, characterized in that an electrical board (20) on which electronic components are mounted is provided integrally with the optical board (22), and the electrical board (20) is seated on the stepped portion (14).
Or the optical module according to 2.