JP2002107568A - Optical fiber fixture and method of assembling the same - Google Patents

Abstract

(57) [Summary] (with correction) [PROBLEMS] To prevent the bending strength and the tensile strength of an optical fiber of a solder fixing part from being broken due to deterioration due to internal stress and thermal stress of the solder, and to the solder shape of the solder fixing part. However, it prevents an obstacle such as covering the tip of the optical fiber and preventing conduction of light. An optical fiber fixture is formed by inserting a tip of an optical fiber (1) into a through hole of a ferrule (3) and joining the same.
The optical fiber 1 and ferrule 3 are joined with AgSn solder 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention is used for optical communication and the like. The present invention relates to an optical fiber fixture using a ferrule for fixing an optical fiber and an assembling method thereof.

[0002]

2. Description of the Related Art Conventionally, in a module incorporating an optical semiconductor device used for optical signal processing such as optical communication, as a method of coupling light emitted from the optical semiconductor device to an optical fiber, a lens coupling system using a lens, There is known a spherical optical fiber coupling system in which an optical fiber tip is formed in a lens. At this time, an optical fiber fixing device for fixing an optical fiber is used for a semiconductor laser module or the like, but in recent years, it is also used for a submarine, and a hermetic sealing structure is required for ensuring reliability.

As shown in FIG. 5, a conventional optical fiber fixing device has a tip of an optical fiber 1 inserted into a ferrule 3, sealed with an epoxy resin 6, and further introduced into a cylindrical shape integrally formed with a package. The inside 14 was hermetically sealed with a low-melting glass 15 or the like (see JP-A-7-92335). In some cases, the outer peripheral side surface of the ferrule 3 is fixed to a package or the like by soldering or welding, and an element such as a laser diode is disposed in the package at the distal end side (upper side in the drawing) of the optical fiber 1.

[0006] As another structure, as shown in FIG. 6, an optical fiber in which an optical fiber 1 and a ferrule 3 are joined by providing a solder 7 in a meniscus shape using PbSn solder or AuSn solder at the end of the ferrule 3 (See Japanese Patent Application Laid-Open No. 61-33005, Japanese Patent Application Laid-Open No. 3-112)
710 publication).

[0005]

However, in the optical fiber fixing device shown in FIG. 5, since the epoxy resin 6 and the low melting point glass 15 are burned or melted by low heat, they are further heated by post-processing solder. There was a problem that was not suitable for.

Further, if PbSn solder is used in the optical fiber fixing device shown in FIG. 6, since the melting point is as low as about 180 ° C., there is a possibility that the alignment may be deviated during heating in a later step.
The use itself is regarded as an environmental problem. In addition, AuS
Since the use of n solder has a high melting point and too high hardness, the coating tends to be burned out, the internal stress increases, and problems such as fiber breakage during a heat cycle tend to occur. There is a problem in that the fiber is closer to the vertical with respect to the fiber 1 and is more vulnerable to bending from a lateral load and is more likely to be broken.

In the structure of FIG. 6, the stress is alleviated by reducing the angle between the surface of the solder 7 and the optical fiber 1 to form a meniscus shape. However, when the angle is reduced, the solder 7 inevitably protrudes longer. Therefore, if the amount of protrusion of the tip of the optical fiber 1 from the ferrule 3 is small, the solder 7
Cover the tip of the optical fiber 1.

[0008]

In view of the above, the present invention provides
In an optical fiber fixing device in which the tip of an optical fiber is inserted into a through hole of a ferrule and joined, the optical fiber and the ferrule are joined with AgSn solder.

Further, in an optical fiber fixing device in which the tip of an optical fiber is inserted into a through hole of a ferrule and joined, an optical fiber protruding from the tip of the ferrule is fixed with solder, and the solder has two or more steps. It is characterized by a dome shape.

[0010] Further, the tip of the optical fiber is inserted into the through hole of the ferrule, and a solder preform is arranged around the optical fiber protruding from the tip of the ferrule at an interval.
It is characterized in that only the vicinity of the ferrule end face of the solder preform is heated and melted and fixed.

[0011]

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

FIG. 1 is a sectional view of an optical fiber fixture of the present invention.

The tip of the optical fiber 1 is inserted into the through hole 3a of the ferrule 3, and the uncoated portion 1a of the optical fiber 1 projecting from the tip 3b of the ferrule 3 and the tip 3b are joined with the solder 2. ing.

Also, the lens processing etc. are performed.
Coating removal part 1 of optical fiber 1 protruding from ferrule 3
The coating 1b of the optical fiber 1 extends on the tip side (the upper side in FIG. 1) of FIG.

Here, AgSn solder is used as the material of the solder 2. In the present invention, the reason why AgSn solder is desirable is that its hardness is 13HB and 11HB of AuSn solder.
Since the hardness is lower than that of 8HB, the optical fiber 1
This is because there is an effect that the internal stress applied to is reduced.
Also, when compared with the melting point of AuSn solder of 280 ° C., AgS
At a melting point of 220 ° C. for n-solder, a small amount of heat is required for heating and melting, so that a small thermal stress is generated.

Further, as the composition of the solder 2, an alloy solder having a composition ratio of Ag in a range of 2 to 10% by weight and the remainder of Sn is used, and a composition ratio of Ag is preferably 3 to 6% by weight. Note that components other than Ag and Sn can be slightly contained.

Ferrule 3 usually contains iron, cobalt,
A tube-shaped ferrule made of a Kovar-based alloy made of nickel is used, but nonmetallic materials such as stainless steel metal, ceramics such as zirconia and alumina, and glass may be used.

A gold plating is formed on the tip surface of the ferrule 3 for the purpose of improving the wettability with respect to the solder 2, and the plating thickness is in the range of 0.2 to 10 μm, preferably 0.5 to 5 μm.
Control with μm.

Nickel or the like is usually used for plating the underlayer of gold plating. However, the plating is not particularly limited as long as it has good adhesion to gold plating.
It is controlled in the range of 0.2 to 10 μm, and preferably, it is controlled in a range of 0.1 μm.
Control is performed at 5 to 5 μm.

As the optical fiber 1, a single-mode or multi-mode quartz glass fiber can be used, and the coating 1b made of resin is removed.
The tip of the coating removing portion 1a exposing the inner quartz portion having a diameter of 0.125 mm is subjected to cleave end and lens processing with a cleaver, and the coating removing portion 1a is plated through metallization.

As for the metallization between the coating removal portion 1a and the plating, it is desirable to form a film such as CVD or PVD from the viewpoint of adhesion, but the film forming material has adhesion to both quartz and plating. Good things are needed.

FIG. 2 is a sectional view showing another embodiment of the present invention.

As in the first embodiment, the optical fiber 1 and the ferrule 3 are joined by the solder 2. However, the material of the solder 2 is not limited to AgSn. It is the first stage 2 of the dome shape
It has a mirror-like shape in which a dome-shaped second stage 2b is stacked on top of a.

Therefore, the solder 7 is easily elastically deformed when the optical fiber 1 is bent with the interface 11 between the first stage 2a and the second stage 2b as a fulcrum, so that it has a function of absorbing stress.

Next, a method for assembling the optical fiber fixture of the present invention will be described.

As shown in FIG. 3, the tip of the optical fiber 1 is inserted into the through hole 3a of the ferrule 3, and the solder preform 16 is inserted around the optical fiber 1 protruding from the tip 3b of the ferrule 3. By heating the vicinity of the front end face 3b of the ferrule 3, the solder preform 16 is melted and the front end of the optical fiber 1 and the ferrule 3 are joined.

The method of assembling the optical fiber fixture shown in FIG. 1 is to provide a gap 5 between the optical fiber 1 and the solder preform 16 by controlling the inner diameter of the solder preform 16 so that the ferrule of the solder preform 16 3 By melting only the vicinity of the front end face 3b and fixing the open end 12 side without completely melting, it is possible to minimize the stress directly applied to the optical fiber 1 while maintaining the airtightness of the solder 2. As a method of heating the vicinity of the tip surface 3b of the ferrule 3 of the solder preform 16, high-frequency heating, laser heating, or the like is used.

In the method of assembling the optical fiber fixture shown in FIG. 2, first, a bonding structure as shown in FIG. 1 is formed, another solder preform 16 is mounted on the solder 2, and the optical fiber 1 and the solder The gap 5 is provided between the reform 16 and
By melting only the vicinity of the end face of the ferrule 3 of the solder preform 16 and fixing the open end 12 without completely melting the solder preform 16, it is possible to keep the airtightness of the solder 2 and minimize the stress directly applied to the optical fiber 1. A dome shape having two or more steps can be used.

In the above assembling method, the gap 5 between the optical fiber 1 and the solder preform 16 is 1 to 100.
μm, preferably 1 to 10 μm, is appropriate for ensuring airtightness.

[0030]

EXAMPLE Here, an experiment was conducted by the following method.

The optical fiber fixture of the present invention shown in FIG. 1 was manufactured using solder 5 of 5% by weight of Ag and 95% by weight of Sn. As a comparative example, the shape of the solder 2 was the same, but the material of the solder 2 was Au.
80% by weight, Sn 20% by weight or Pb 60% by weight, Sn40
An optical fiber fixture having a weight% was manufactured.

The material of the ferrule 3 is iron 70% by weight, C
o 17% by weight and Ni 3% by weight of Kovar were used.

Each sample was subjected to a heat cycle test to measure bending strength and tensile strength.

Here, the heat cycle conditions were controlled in a temperature range of -40 ° C. to 85 ° C., a temperature rise / fall rate of 10 ° C./min, and a temperature residence time of 30 minutes. Samples were sampled at 200, 600, and 1800 cycles, and the strength was measured.

As shown in FIG. 4A, the bending strength is measured by fixing the pin 8 at a predetermined end of the optical fiber 1 and moving the pin 8 along a locus having a radius of curvature of 10 mm. The fiber was pushed in the direction 9 and the angle X when the optical fiber 1 was broken was measured to determine the bending strength.

FIG. 4 shows a method of measuring the tensile strength.
As shown in (b), the ferrule 3 is fixed, the tip of the optical fiber 1 is held, and the optical fiber 1 is pulled in the load direction 9.
Was measured by a push-pull gauge to determine the tensile strength.

The results are shown in Table 1 (n = 30 for each cycle number).
Average value).

[0038]

[Table 1]

From the above results, Conventional Example 1 using PbSn solder is excellent in bending strength and tensile strength in the initial stage and after 1800 cycles, but is suitable for heating by further soldering in post-processing because of its low melting point. In addition, the use of Pb itself poses an environmental problem and cannot be used.

In the conventional example 2 using the AuSn solder, the bending strength and the tensile strength were weak at the initial stage and were not endurable.

In comparison with this, the one using the AgSn solder of the embodiment of the present invention has the same bending strength and tensile strength as the PbSn solder, so that it can be used for heating by further solder in a later process. The melting point was within the range of endurance, and was excellent.

Next, an optical fiber fixture was manufactured using the two-step dome-shaped solder 2 of the present invention shown in FIG.
An optical fiber fixing jig was manufactured using the meniscus-shaped solder 7 shown in FIG. 4, and the bending strength test was performed by the method shown in FIG.

The results are shown in Table 2 (each n = 30 average).

[0044]

[Table 2]

From the above results, the conventional meniscus-shaped solder 2 broke the optical fiber 1 at 70 degrees, while the dome-shaped solder 7 of the present invention broke at 100 degrees, so that it was significantly bent. It was noted that the strength was improved.

This is presumably because the thickness of the solder 2 is reduced, and the stress near the boundary between the optical fiber 1 and the solder 2 is reduced.

[0047]

As described above, according to the present invention, the optical fiber and the ferrule are joined by the AgSn solder in the optical fiber fixture in which the tip of the optical fiber is inserted into the through hole of the ferrule and joined. By forming the solder into a dome shape with two or more steps, a highly reliable optical fiber fixture having high bending strength and tensile strength can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an optical fiber fixture of the present invention.

FIG. 2 is a sectional view showing another embodiment of the optical fiber fixing device of the present invention.

FIG. 3 is a cross-sectional view illustrating an assembling method of the optical fiber fixture of the present invention.

FIG. 4 shows an evaluation method of the optical fiber fixture,
(A) is a figure which shows bending strength and (b) is a figure which shows tensile strength.

FIG. 5 is a sectional view showing a conventional optical fiber fixture.

FIG. 6 is a sectional view showing a conventional optical fiber fixture.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 optical fiber 2 solder 3 ferrule 5 gap 6 resin 7 solder 8 pin 9 load direction 10 bending angle 11 fulcrum 12 open end 13 gap 14 package introduction part 15 low melting glass 16 solder preform

Claims (3)

[Claims] 1. An optical fiber fixing device comprising an optical fiber and a ferrule, wherein the optical fiber and the ferrule are fixed with AgSn solder. 2. An optical fiber fixture, wherein the tip of an optical fiber is inserted into a through-hole of a ferrule, and an optical fiber protruding from the tip of the ferrule is fixed with solder. An optical fiber fixture having a dome shape. 3. An end of an optical fiber is inserted into a through-hole of a ferrule, and a solder preform is arranged at an interval around an optical fiber protruding from the end of the ferrule, and only in the vicinity of the ferrule end face of the solder preform. And fixing the same by heating and melting.