JPH0476446B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a sealing bushing for supplying glass fibers, the fibers being fixed in holes in metal parts by soldering.

[Prior Art] Such fiber bushings are used, for example, for optical communications, in particular for hermetically sealed housings of electrical-optical or opto-electrical parts that must be protected against environmental influences. It will be done.

Metal soldering, which has a higher heat resistance than adhesives, is preferably used to attach the exposed glass fibers. In addition, it protects the glass fiber from "creeping" and is waterproof. As indicated by the documents DE-OS 2721 991 and 30 46 415,
It is necessary to metallize the glass fibers before soldering. The metallization must meet several qualitative requirements. On the one hand, it must adhere very well to the glass fiber. On the other hand, the metallization must be easily solderable. In order to achieve proper adhesion, it is essential that the fiber surface be very clean. Therefore, the surface must be cleaned very carefully. Generally, this is done in several selective treatment steps, such as by immersion in hot sulfuric acid with successive washings and drying in deionized water, or in hot sulfuric acid with successive washings and drying. This is done by etching the glass fiber.

[Problems to be Solved by the Invention] However, coatings that can provide strong adhesion are often difficult to solder, or cannot be soldered at all. Therefore, two or more metals must be coated simultaneously, either sequentially or as a mixture. This can be done by vacuum deposition or sputtering or by wet chemical processing. As a result, it is necessary to use different types of tools and equipment in the production of glass fiber bushings. Therefore, it is actually difficult to provide a metallized coating on glass fibers, and therefore hermetic sealing with solder is rarely performed in locations where optical transmission equipment is installed. .

Furthermore, even during manufacturing, glass fibers are very fragile, so when applying a metallized coating,
Breakages are particularly likely to occur at the boundary points between treated and untreated surfaces, ie at the transition points with the metallized coating. Additionally, it has been discovered that metallized coatings tend to dissolve into the solder during soldering. As a result, the adhesive force decreases or it becomes impossible to adhere completely. The molten solder precipitates as it cools, thereby separating the solder from the glass fiber and creating a capillary tube. Once a capillary is formed, it can no longer function as a hermetic seal because leakage occurs through it. Also, when tensile strain occurs, the force pulls the glass fiber away from the solder.

It is therefore an object of the invention to provide a system which requires low manufacturing costs, has good robustness and, if necessary, can be manufactured at the installation site of the transmission device.
It is an object of the present invention to provide a glass fiber hermetic bushing that does not require a metallized coating.

Means for Solving the Problems and Effects The present invention provides a glass fiber sealing bushing having a metal portion in which the glass fiber is fixed in a hole by solder. forming a continuous region surrounding longitudinally adjacent first and second portions of the uncoated glass fiber, the outer periphery of the solder region surrounding the first portion of the glass fiber being the inner wall of the hole in the metal portion; and the solder surrounding the second portion of the glass fiber has no adhered metal parts that would prevent the solder from shrinking while being adhered to the glass fiber. The second portion of the glass fiber is characterized in that the outer peripheral surface of the second portion is hermetically joined to the solder region to form a sealing bushing.

Conventionally, it has not been possible to seal a glass fiber without a metallized coating inside a hole in a metal member with solder because the molten solder contracts as it cools and solidifies. When molten solder is applied to the surface of a glass fiber and then cooled, the solder contracts while being bonded to the surface of the glass fiber, and after cooling, the solder can be bonded to the surface of the glass fiber in a sealed state. However, if a glass fiber is placed inside a hole in a metal member and molten solder is filled between the glass fiber and the inner wall of the hole in the metal member, the solder will flow between the glass fiber and the inner wall of the hole in the metal member. It contracts when it is attached to both, and cannot contract freely like it would when it is bonded only to the surface of the glass fiber, and because it is attached to the inner wall of the hole, it shrinks at the interface between the glass fiber and the solder. When a force is applied to separate the two, a separation occurs at the interface between the glass fiber and the solder, or a crack forms and a leak path is formed along this interface, resulting in a satisfactory seal. I was unable to do so.

In contrast, in the present invention, as described above, a continuous region surrounding the longitudinally adjacent first and second portions of the glass fiber without the stripped metallized coating is formed; The outer periphery of the solder region surrounding the first portion of the fiber is hermetically joined to the inner wall of the hole in the metal portion, and
Because there was no bonded metal part on the outside of the solder surrounding the glass fiber that would prevent the solder from shrinking when it was bonded to the glass fiber, this second part would shrink the outer peripheral surface of the glass fiber during cooling. Since shrinkage of the glass fiber and solder is not prevented in the bonded state, it is possible to bond the glass fiber in a sealed state even without a metallized coating provided on the outer surface of the glass fiber.

The second portion of the glass fiber can be configured as a portion that projects outside the hole. If the protruding glass fiber is surrounded by a solder region that is continuous with the inside of the hole, the solder will have a metallized coating so that it will not be hindered from shrinking while being bonded to the outer peripheral surface of the glass fiber. It can be hermetically bonded around unconventional glass fibers.

However, in order to obtain a good seal in this case, the solder must be hermetically bonded to the glass fiber over a sufficient length outside the hole. However, it is difficult to stably obtain the desired height by simply forming a bead-shaped solder portion outside the hole exit. Accordingly, in a first form of the invention, a second metal part for applying solder over a predetermined length in the longitudinal direction of the glass fiber is arranged at a distance from the front face of the hole in the metal part. By joining solder to this as well, the solder is reliably joined to the surface of the glass fiber between these metal parts.

In a second form of the invention, the metal part is a metal sleeve with a non-solderable coating provided on the inner wall of the hole over a part of the length of the hole, and the second part of the glass fiber is The outer periphery of the surrounding solder area corresponds to the area of the part with the non-solderable coating in the hole so that the outside of the solder is not joined to the metal part in this part and is hermetically joined to the solder area around the glass fiber. I'm letting you do it.

In a third form of the invention, the metal part is a metal sleeve with a recess partially exposing the hole on the side, and the outer periphery of the solder area surrounding the second part of the glass fiber corresponds to the area of the recess. At this portion, the outside of the solder is not bonded to the metal portion, and is bonded to the solder area around the glass fiber in a sealed state.

Various advantages are provided by the present invention. It is no longer necessary to metallize the glass fiber. Complex cleaning steps previously required can be omitted. The bushing can obtain a high degree of firmness when the bushing is produced in the field. Further advantages of the invention will become apparent from the description below.

EXAMPLES The present invention will now be described with reference to the accompanying drawings, which illustrate preferred embodiments of the invention.

In the drawings, the first metal part of the sealed glass fiber bushing is designated with the reference number 1.
The first metal part shown in FIGS. 1, 2, and 4 is preferably a wall or support plate of a sealed housing, for example positioned within such a housing. The metal part 1 is drilled with a hole 2 in which a glass fiber 3 is fixed by soldering. The glass fiber 3 is the end of the optical waveguide which has been stripped of its primary coating and has no exposed metallized coating. During soldering, the hole 2 is filled over all or part of its length with molten solder 4. The solder 4 is further applied to at least one outer surface 5 of the metal part 1 outside the hole 2.
It is formed to be joined to the glass fiber 3 as a bead-shaped raised solder portion 6.

The solder 4, which is melted during cooling, solidifies while shrinking. Therefore, the solder between the inner wall of the metal part 1 inside the hole 2 and the surface of the glass fiber 3 contracts, and at that time, since the solder is attached to the inner wall of the metal part 1, which has strong adhesive strength, , the solder 4 is separated at least partially from the surface of the glass fiber 3 by being subjected to a force that pulls it away from the surface of the glass fiber 3 (this is exaggerated in the figure to show the space between the glass fiber and the solder). (The interface between the glass fiber and the solder will be at least partially separated, although not all of it will be completely separated.) Therefore, a leakage path is formed and a satisfactory seal cannot be obtained at the interface between the solder and the glass fiber in this area. However, the bond between the solder 4 and the inner wall of the hole 2 of the outer metal part 1 is obtained in a well-sealed state. On the other hand, the bead-shaped raised part 6 of the solder 4 located outside the hole can shrink while being bonded to the glass fiber 3 because there is no metal part 1 attached to the outside. Solder 4 is hermetically bonded around glass fiber 3.

In this way, the solder 4 is hermetically bonded to the glass fiber 3 outside the hole 2, and is also hermetically bonded to the metal part 1 inside the hole 2, thereby connecting the metal part 1 and the glass fiber 3. It is possible to obtain a sealed joint between the two.

In this case, in order to obtain a good sealing condition, hole 2
It is necessary that the solder 4 is hermetically bonded to the glass fiber 3 over a sufficient length on the outside of the glass fiber 3.
However, the bead-shaped solder portion 6 shown in Figure 1 is caused by the surface tension of the molten solder.
It is difficult to stably obtain the desired height because it is affected by various factors such as viscosity and adhesion, and if the height of the bead-shaped solder portion 6 is too low, the solder 4 may not be long enough. Glass fiber 3
Since it is not possible to form a hermetic joint with the material, a satisfactory sealing state cannot be obtained.

In the present invention, the second metal part 7 is separated from the metal part 1 by a predetermined distance for adhering solder to the surface of the glass fiber over a predetermined length in the longitudinal direction of the glass fiber 3 as shown in FIG. The solder 4 is reliably bonded to the surface of the glass fiber 3 between these metal parts 1 and 7 by arranging the metal parts 1 and 7 with solder. As shown in the example, this second metal part 7 is a shank pressed from sheet metal with a supporting projection whose free end 8 is fixed to the outside 5 of the first metal part 1. Figure 3). A simple wire stirrup instead of a shuttle
may be used to limit the height of the solder 6. Solder 4 along glass fiber 3 during cooling
It is important that the process allows the shrinkage of the material to occur without significant hindrance.

In the embodiment of sealed glass fiber bubbling shown in FIGS. 4 to 6, the second metal part 7 is spaced apart from the first metal part by simple tools during soldering. It is held in a relationship that After the solder 4 has solidified,
The glass fiber 3 is hermetically implanted and the second metal part 7 is mechanically fixed to the first metal part 1 by means of a solder 6. The second metal part 7 connected by the solder body 6 has a ferrule, a ring,
It can be designed as a perforated disc, a support plate or a wall of the second housing. In what is shown in FIGS. 5 and 6, the first metal part 1 is a sleeve to which a solder body 6 is attached at its front end.

In FIG. 7, the sealing bushing 1' is e.g.
It is also attached to an opening in the housing wall 2' which is airtightly connected. This bushing is constituted by a metal sleeve 3' with a coated fiber 4' fixed therein. The forward part 5' of the metal sleeve 3' has a hole 6' with a relatively small diameter for receiving the exposed glass fiber 7', and the rear part 8' of the sleeve 3' receives a portion of the fully coated fiber 4'. It has a hole 9 with a larger diameter for receiving it.

Bushing 1' shown in FIGS. 7 and 8
In the embodiment, the wall of part of the length of the hole 6' is
After the metal sleeve 3' has been produced, it is provided with a non-solderable coating 10. This coating 10, which is a solder insulation paint or is formed by an oxidized surface of the hole wall, covers the hole 6'.
It is attached to either the front or rear part, whichever is appropriate.

The glass fiber 7', which has been previously stripped of its jacket and primary coating in the usual manner, is then
It was fed through a metal sleeve for soldering by heating it to the appropriate temperature and soldering in a solder bath. After being removed from the bath, the metal sleeve 3' and the soldered connection point are cooled and the solidified solder 11 has contracted on the exposed glass fiber 7' in the area of the non-wetting coating 10, sealingly sealing the glass fiber. 7′. In the uncovered area of the hole 6', the solder 11 separates from the glass fiber 7' during solidification;
Form a seal with the wet hole wall. In this way, the transition from one part of the soldered area to another is ensured by the metal sleeve 3', which is held firmly in the solder 11 in some lengths due to the different coefficients of thermal expansion and is torsion-free. A seal is formed between certain glass fibers 7'. If an unacceptable tensile strain occurs, the glass fiber will not fail at or near the soldered joint, but will fail at a location away from such joint. In order to prevent unintended transmission of tension to the glass fiber 7', the coated fiber 4' is glued into the rear part of the hole 9 and/or with the help of a shrink tube 13 surrounding the rear part 8' of the sleeve. It is fixed to the metal sleeve 3'.

Another embodiment of a metal sleeve 3' that ensures that the solder 11 contracts on the exposed glass fiber 7' as the soldered joint cools is shown in FIGS. 9-12. In order to avoid completely wetting the hole walls with the solder 11, some wall portions which were provided with a non-solderable coating in the previously described embodiments are removed. This is achieved by providing the front part 5' of the metal sleeve 3' with a recess 12 which partially exposes the hole 6'. The glass fiber 7' exposed here floats on top of the melted solder 11 during soldering and must be kept below until the solder solidifies.

Yet another result is that the solder 11 in the area of the depression 12
is to hermetically surround the exposed unmetallized glass fiber 7'. In contrast, in the region of the hole 6' without a recess, the solder 11 is bonded to the wall of the hole in an essentially sealingly rigid manner.

The recess 12 is, for example, a slot extending in the longitudinal direction of the hole 6', such a slot having side walls that are parallel to each other or V-shaped. Alternatively, it may be constructed by cutting the metal sleeve 3' to reduce its cross section. The wish 12 may start at the front end of the metal sleeve 3' or be positioned in this way in a region further away from the front part 5', where the complete sleeve section is provided in front. The end surface 14 of the recess 12 is thus curved (FIG. 10), beveled, or perpendicular to the axis of the sleeve (FIG. 11).

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a portion of a sealed glass fiber bushing. FIG. 2 is a longitudinal cross-sectional view of a portion of a glass fiber bushing with a shackle attached to the outer surface of the bushing. 3 is a top view of the shackle of FIG. 2; FIG. FIG. 4 is a longitudinal sectional view of a portion of a glass fiber bushing with a sleeve placed in front of the bushing. FIG. 5 is a longitudinal sectional view of a portion of a glass fiber bushing with a ring placed in front of the bushing. FIG. 6 is a longitudinal sectional view of a glass fiber bubbling consisting of two sleeves with a solder body applied between the sleeves. FIG. 7 is a longitudinal cross-sectional view of a portion of a sealed glass fiber bushing applied to an opening in the housing wall. FIG. 8 is a longitudinal sectional view of a portion of a metal sleeve provided for receiving a glass fiber to be soldered. FIG. 9 is a perspective view of the front part of the metal sleeve with recesses. 10 is a longitudinal sectional view of the front portion of the metal sleeve of FIG. 9; FIG. FIG. 11 is a perspective view of a metal sleeve with recesses in a modified form. 1st
2 is a longitudinal sectional view of the front part of the metal sleeve of FIG. 11; FIG. 1... Sealed glass fiber bubbling, 2...
Hole, 3...Glass fiber, 4...Solder, 5...
...Outer surface, 6...Solder, 7...Metal part, 8
... Free end, 9 ... Hole, 10 ... Coating, 11 ... Solder, 12 ... Recess, 13 ... Shrink tube, 14 ... End surface of recess, 1' ... Sealing bushing, 2' ...housing wall, 3' ... metal sleeve, 4' ... coated fiber, 6' ... hole, 7'
...Glass fiber.

Claims (1)

[Claims] 1. In a glass fiber sealing bushing in which the glass fiber has a metal part fixed in the hole by solder, the solder is applied to the stripped glass fiber without metallized coating. forming a continuous region surrounding longitudinally adjacent first and second portions, the outer periphery of the solder region surrounding the first portion of the glass fiber being hermetically joined to the inner wall of the hole in the metal portion; the second portion of the glass fiber is a portion protruding outside the hole, and the solder area around the second portion is hermetically bonded around the glass fiber without a metallized coating; a second metal portion defining a solder height that is vertically hermetically bonded to said second portion of glass fiber and spaced from a front face of said hole in said hole-bearing metal portion; , a hermetic bushing characterized in that the solder region is also joined to this second metal part. 2. In glass fiber sealed bushings in which the glass fiber is provided with a metal part fixed in the hole by solder, the metal part is provided on the inner wall of the hole over part of the length of the hole. a metal sleeve having an uncoated coating, the solder forming a continuous region surrounding longitudinally adjacent first and second portions of the glass fiber without a stripped metallized coating; an outer periphery of a solder region surrounding said first portion of glass fiber is hermetically joined to an inner wall of a hole without said non-solderable coating of a metal portion; and said second portion of glass fiber The outer periphery of the solder area surrounding the hole corresponds to the area of the part with the non-solderable coating of the hole, and the solder area around said second part of the glass fiber corresponds to the area of the part of the hole with the non-solderable coating, and the solder area around said second part of the glass fiber does not have a metallized coating. A hermetic bushing characterized by being hermetically joined to its surroundings. 3. A glass fiber sealed bushing comprising a metal part in which the glass fiber is fixed in the hole by solder, the metal part being a metal sleeve with a recess on the side surface partially exposing the hole; the solder forming a continuous region surrounding longitudinally adjacent first and second portions of the glass fiber having no stripped metallized coating, the solder surrounding the first portion of the glass fiber; The outer periphery of the region is hermetically joined to the inner wall of the hole of the metal part, which does not have the recess, and the outer periphery of the solder region surrounding the second part of the glass fiber corresponds to the region of the recess and the glass A hermetic bushing, characterized in that the solder area around the second portion of the fiber is hermetically bonded around the periphery of the glass fiber without metallization.