JPH0513481B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical module that fixes an optical fiber to an optical module used in an optical communication system such as a data link or an optical LAN that uses light as an information transmission medium. This invention relates to a fiber fixing method.

[Conventional technology]

As such an optical module, for example, an optical module in which an optical fiber is optically bonded to an optical operating component such as a semiconductor laser, a PIN photodiode, or an optical integrated circuit is known.

An example is shown in FIG. The illustrated optical module is a receiving optical module in which an optical fiber 1 and a PIN photodiode 2 are optically coupled, and the light emitted from the tip of the optical fiber 1 is used as a light receiving element.
The light is made to enter the light receiving section of the PIN photodiode 2.

In this optical module, the core portion of the optical fiber 1 is exposed at the tip portion 1a, and this exposed portion is formed with a so-called metallized fiber portion that is plated with metal. The tip portion 1a of the optical fiber 1 on which the metallized fiber portion is formed is mounted on a fixing base 5 fixed on a metal package 3 in the vicinity of the PIN photodiode 2.
It is precisely positioned on the top and then soldered to secure it in place. Note that the PIN photodiode 2 is connected to a capacitor, a resistor, and a resistor (not shown).
It is fixed on a hybrid IC board 6 on which electronic components such as ICs are mounted.

[Problem to be solved by the invention]

When fixing the optical fiber to the above-mentioned optical module, the tip portion 1a of the optical fiber 1 is fixed on the fixing table 5, and cream solder or filamentous solder is used for this fixing.

When cream solder is used, the flux in the cream solder evaporates during soldering, and the PIN photodiode 2 placed oppositely evaporates.
In some cases, it adhered to the light-receiving part of the camera, contaminating this part.

Furthermore, when fixing an optical fiber using filamentous solder, the filamentous solder may not be heated sufficiently, and in such a case, the filamentous solder, which is still in a solid state, may touch the tip 1a of the optical fiber 1. Therefore, there was a problem that the position of the distal end portion 1a, which was once accurately positioned, was shifted, resulting in poor workability.

The present invention has been made to solve the above problems, and its main purpose is to prevent flux from adhering to the light-emitting and light-receiving surfaces of optically actuated components such as PIN photodiodes when fixing optical fibers to optical modules. An object of the present invention is to provide an optical fiber fixing method that prevents this.

Another object of the present invention is to provide an optical fiber fixing method that improves the workability of the optical fiber fixing work.

[Means to solve the problem]

The optical fiber fixing method according to the present invention has been made in view of the above object, and in the optical fiber fixing method for fixing the optical fiber to the optical module, flux is applied to the fiber fixing surface of the optical fiber fixing table. A first step of plating with a brazing filler metal containing the fiber, a second step of fixing the optical fiber fixing base onto the mounting board of the optical module, and a second step of plating the optical fiber with a brazing filler metal containing no flux;
and a third step of arranging the preform having a bent shape on the fiber fixing surface so that a part of the preform is separated from the fiber fixing surface, and fixing the preform in the opening of the preform. After inserting the desired optical fiber, it
A fourth step is to adjust the optical axis of the optical fiber, and a fifth step is to fix the optical fiber on an optical fiber fixing table by heating the preform and once melting it, then stopping this heating and solidifying it again. It consists of a process.

[Effect]

Since the preform is made of a brazing filler metal that does not contain flux, when the preform is heated and melted in the fifth step, no flux is generated from the preform, and photoactivation is possible. Flux is prevented from adhering to the parts.

Further, if a brazing filler metal that does not contain flux is used, it is usually impossible to fix the optical fiber to the optical fiber fixing table due to poor solder wettability. Therefore, as a pretreatment, the fiber fixing surface is plated with a brazing material containing flux in the first step. As a result, even when using a brazing filler metal that does not contain flux,
An optical fiber can be fixed to a fiber fixing surface.

On the other hand, in the fourth step, the optical fiber is inserted into the gap formed between the preform and the fiber fixing surface to adjust the optical axis, and then in the fifth step, the preform is heated, melted, and solidified. During the work in this fifth step, the operator does not touch the optical fiber, so there is no risk of the optical axis of the optical fiber being shifted, which would otherwise be caused by the operator touching the optical fiber.

〔Example〕

Hereinafter, the optical fiber fixing method according to the present invention will be explained in order of steps with reference to FIG.

Hybrid as a mounting board for optical modules
A PIN photodiode 2, which is a photo-activated component, is fixed on the IC board 6.

First, the fixing base 5 of the optical fiber 1 is fixed at a position opposite to this PIN photodiode 2.
Prior to this step, at least the fiber fixing surface 5b of the fixing base 5 is plated with a brazing material containing flux such as cream solder.

Next, the plated fixing base 5 is fixed onto the hybrid IC board 6. This fixation requires
Brazing filler metal with a relatively high melting point, such as A _u with a melting point of 280℃
- Die bonding by brazing using S _o solder or the like. Note that it is also possible to perform plating and die bonding of the fixing base 5 at the same time using the same brazing material.

Next, the fiber fixing base 5b in the fixing base 5
A preformed body 7 made of a flux-free brazing material is fixed to. This preformed body 7 has a shape such as a U-shape, a U-shape, or a V-shape, which is bent so that a part thereof crosses over the upper part of the fiber fixing surface 5b. (Figures 2 to 4). Note that it is desirable that the melting point of the brazing material forming this preformed body 7 is lower than that of the brazing material used for die-bonding the fixing base 5.

This preformed body 7 is fixed by a fiber fixing surface 5.
Concave portions 5a are formed at two locations b, and the two leg portions of the preform 7 are fitted into each of the concave portions 5a, respectively. By fixing the preform 7 to the fiber fixing surface 5b in this way, a gap 7a is formed between the preform 7 and the fiber fixing surface 5b.

Next, the optical fiber 1 to be fixed is inserted into the cavity 7a of the preform 7, and the optical fiber 1
Bring the tip of the PIN photodiode 2 close to the PIN photodiode 2 to a predetermined distance. Thereafter, the optical axis of the optical fiber 1 is adjusted so that the optical axis coincides with the PIN photodiode 2. At this time, since the inner diameter of the gap 7a is sufficiently larger than the outer diameter of the optical fiber 1, by slightly shifting the position of the optical fiber 1 within the gap 7a, the PIN
The optical axis can be aligned with the photodiode 2.

Next, after completing the optical axis adjustment of the optical fiber 1,
The fixing table 5 and the preformed body 7 are heated to once melt the preformed body 7. After the preformed body 7 is melted, heating is stopped, and the melted preformed body 7 is cooled and solidified. With this, the optical fiber 1 is fixed to the fixing base 5.

The optical fiber shown in this embodiment is a metallized fiber whose tip is plated with metal in advance to make it suitable for brazing.

Further, in this embodiment, the leg portions of the preformed body 7 are 2
Both books fit into the recess 5a, but the cross section of the leg is formed into a prismatic shape such as a quadrangle, and the recess 5a
If a is also formed into a rectangular shape in accordance with these to prevent rotation of the preformed body 7 about its legs, the lengths of both legs are different and only one leg has the recess 5a.
It is also possible to use a J-shaped preform that fits.

Further, in this embodiment, the fixing base 5 is provided on the hybrid IC board 6, but it may be provided on the package 3 as in the conventional case.

〔Effect of the invention〕

As explained above, according to the optical fiber fixing method according to the present invention, in the first step, the fiber fixing surface is plated in advance with a flux-containing brazing material, so that in the fifth step, the fiber fixing surface is plated with a flux-free brazing material. Even when the preformed body made of brazing material is heated and melted, the solder wettability is good. Therefore, even when using a brazing filler metal that does not contain flux, it is possible to fix the optical fiber to the fiber fixing surface of the optical fiber fixing table.

In addition, since the preform was formed from a brazing filler metal that did not contain flux, it could not be heated or
There is no risk of flux occurring during melting,
It is possible to prevent flux from adhering to optically actuated parts.

Furthermore, in the fourth step, after adjusting the optical axis by inserting the optical fiber into the gap formed between the preform and the fiber fixing surface, the preform is melted and solidified in the fifth step. During the work in the fifth step, the operator does not need to touch the optical fiber, so it is possible to avoid the optical axis shift of the optical fiber that would otherwise occur due to the operator touching the optical fiber.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the main parts of the optical module according to the present invention, FIGS. 2, 3, and 4 are elevational views showing a part of the optical module according to the present invention, and FIG.
The figure is a perspective view showing a conventional optical module. 1...Optical fiber, 2...PIN photodiode, 3...Package, 5...Fixing stand, 5a...
Recessed portion, 6...hybrid IC board (mounting board),
7...Preformed body, 7a...Void portion.

Claims (1)

[Scope of Claims] 1. An optical fiber fixing method for fixing an optical fiber to an optical module, comprising: a first step of plating the fiber fixing surface of the optical fiber fixing table with a brazing material containing flux; a second step of fixing an optical fiber fixing base on the mounting substrate of the optical module; and a preformed body made of flux-free brazing material and having a bent shape, a part of which is fixed to the fiber. a third step of placing the optical fiber on the fiber fixing surface so as to be separated from the fiber fixing surface; inserting the optical fiber to be fixed into the gap formed between the preform and the fiber fixing surface; a fourth step of adjusting the optical axis of the optical fiber with respect to the optical actuating component located at the tip of the inserted optical fiber; and heating the preform to once melt it;
A method for fixing an optical fiber, comprising a fifth step of fixing the optical fiber to the optical fiber fixing table rather than stopping the heating and solidifying it again.