JP3955204B2 - Ferrule and ferrule manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a ferrule used as a fixture for fixing an optical fiber in an optical connector used for facilitating connection of an optical fiber used for optical communication or the like, and a manufacturing method thereof.
[0002]
[Prior art]
In an optical connector used for connecting an optical fiber during construction of an optical communication system, a ferrule is used to fix the optical fiber, and the ferrule is attached to an exterior member (a frame or a housing provided with various engagement / disengagement means). Etc.), an optical connector that makes it easy to connect and disconnect optical fibers is formed. Various types of optical connectors are determined by the JIS standard. Recently, due to the demand for higher density and smaller size, MT type optical connectors that connect ribbon fibers up to 12 cores at once with rectangular ferrules. Demand is increasing. The MT type ferrule is molded by ceramics or plastics, and a mold is used for this molding. As means for producing an MT-type ferrule molding die, machining such as metal cutting, electric discharge machining, and polishing, and etching are used.
[0003]
Also, in the operation of connecting the optical fiber, the optical connector is attached to the tip of the optical fiber, so that the coating of the tip of each optical fiber to be connected is removed and fixed to the joining jig, and each end face is polished. When the center of the fiber and the center of the hole of the ferrule are aligned and adhered or welded to the ferrule, and the ferrule is attached to the exterior member and connected as a connector, the core portions of both optical fibers are brought into contact with each other.
[0004]
The optical fiber housing hole of the ferrule used for fixing the optical fiber is circular in accordance with the cross-sectional shape of the optical fiber, but is formed slightly larger than the diameter of the optical fiber to facilitate the insertion of the optical fiber. Yes.
[0005]
[Problems to be solved by the invention]
However, in the current machining in mold production, it is impossible to continuously process a shape of 100 to 200 μm with an accuracy of 2 μm or less in a region close to 100 to 200 μm. This is because metal distortion generated during the machining process remains around the machining area. Further, in the etching process, the processing accuracy depends on the crystal grain boundary of the metal material due to its principle, and there is a current situation that high-accuracy processing cannot be obtained.
[0006]
In other words, in the MT type ferrule adopted for the purpose of increasing the density and miniaturization of communication facilities, there is a limit to the production of a ferrule molding die, and there is a limit to the miniaturization that is most required for ferrule manufacturing. ing.
[0007]
Furthermore, because the center position of the optical fiber fixed to the ferrule is biased due to the difference between the space size of the optical fiber housing hole provided in the ferrule to accommodate the optical fiber and the actual diameter of the optical fiber, the optical fiber is inserted into the ferrule. Later, when fixing the optical fiber by bonding or the like, it is necessary to align the core of the ferrule with the core of the optical fiber, and this work is the most important and costly process in the optical connector manufacturing process. Yes.
[0008]
That is, when connecting an optical fiber, attaching an optical fiber to a ferrule, and assembling an optical connector, each device is centered using an aligner, a special jig, a measuring instrument, or the like, and the state is maintained. In order to fill the gap between the inner diameter of the ferrule and the outer shape of the optical fiber, it is fixed using an adhesive, auxiliary parts, etc., and these joining assembly techniques are joining assembly techniques that have been used in the early stages of the introduction of optical fibers. This is a factor that prevents the inexpensive and simple optical fiber connection work.
[0009]
Accordingly, the present invention provides a ferrule having a structure capable of easily and accurately aligning optical fibers, and a ferrule manufacturing method capable of producing such a ferrule with high processing accuracy.
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the invention according to claim 1 is directed to an X-ray mask in which a three-dimensional shape of an optical fiber accommodation hole of a ferrule is formed by an X-ray absorption film and an X-ray transmission film. By irradiating the photoresist applied on the substrate by irradiating X-rays from the forming direction, the three-dimensional shape of the X-ray mask expanded in the X-ray irradiation direction is transferred to the photoresist and developed. Then, the non-exposed portion is removed to form a ferrule male or female mold, a ferrule molding mold is created using the male or female mold, and a ferrule is molded using this mold. The method uses an X-ray mask in which a three-dimensional shape formed by an X-ray absorbing film and an X-ray transmitting film is set so that one end of the optical fiber housing hole of the ferrule extends in a tapered shape. And
[0011]
According to a second aspect of the present invention, in the ferrule manufacturing method according to the first aspect, the first holding body and the second holding body exhibiting an outer shape divided so as to bisect the optical fiber accommodation hole of the ferrule. A male type or a female type of the first holding body and the second holding body is formed by using an X-ray mask in which the corresponding three-dimensional shape is formed by an X-ray absorption film and an X-ray transmission film, respectively. Features.
[0012]
According to a third aspect of the present invention, there is provided the ferrule manufacturing method according to the second aspect, wherein the peripheral surface of the optical fiber contacts the optical fiber receiving groove formed in the first holding body by line contact. 2 or more, and in each of the optical fiber receiving grooves formed in the second holding body, each of the X is so shaped that one or more fiber support portions with which the peripheral surface of the optical fiber comes into contact in line contact appear. A feature is that a line mask is created.
[0013]
The invention according to claim 4 is manufactured by the ferrule manufacturing method according to any one of claims 1 to 3.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Next, one embodiment of a ferrule according to the present invention will be described with reference to FIGS.
[0015]
As shown in FIG. 1, the ferrule 1 is composed of a first holding body 2a and a second holding body 2b, and has an external shape that is divided so as to bisect an optical fiber accommodation hole 3 that accommodates an optical fiber. That is, the optical fiber accommodation hole 3 is formed by the optical fiber accommodation groove 3a formed in the first holding body 2a and the optical fiber accommodation groove 3b formed in the second holding body 2b. In addition, although the ferrule 1 shown in this embodiment shall be provided with the two optical fiber accommodation grooves 3 and 3, the number of optical fiber accommodation grooves may be one and three or more may be sufficient as it.
[0016]
And the optical fiber accommodation groove | channel 3a of the said 1st holding body 2a is made into the shape where the fiber support part 4 with which the peripheral surface of optical fiber OF contact | abuts by line contact appears in two right and left, The light of the said 2nd holding body 2b The fiber accommodation groove 3b has a shape in which the peripheral surface of the optical fiber OF appears at one place on the upper surface of the fiber support 4 where the optical fiber OF abuts in line contact. That is, the optical fiber OF is stably held by making line contact with the two fiber support portions 4 and 4 in the optical fiber housing groove 3a of the first holding body 2a. In this state, the second holding body 2b If the optical fiber OF is accommodated in the optical fiber accommodation hole 3 by covering the first holding body 2a, the accommodation position of the optical fiber OF can be made constant by the three contact points. Therefore, when the ferrule 1 according to the present invention is used, it is not necessary to have skill in adjusting the core of the optical fiber as in the conventional ferrule, and the optical fiber can be accommodated easily and quickly. The work efficiency until the optical connector is mounted on the exterior member can be greatly improved.
[0017]
In addition, one end (the side where the optical fiber is inserted) of the optical fiber housing groove 3 of the ferrule 1 shown in the present embodiment is formed with a diameter-expanded portion 5 that expands in a tapered shape. The enlarged diameter portion 5 is useful as a guide when inserting an optical fiber.
[0018]
In the ferrule 1 of the present embodiment, the optical fiber housing hole 3 is configured from a flat surface and a curved surface, but the shape of the optical fiber housing groove 3 is not particularly limited, and the optical fiber OF is placed in the housing hole. It is only necessary to form a fiber support that can be held stably without rattling. For example, the cross-sectional shape may be a polygon made up of only a plane such as a triangle or a quadrangle, or the fiber support portion may appear by forming an elliptical shape.
[0019]
In addition, the ideal shape of the optical fiber housing groove 3 is that when the optical fiber housing groove 3 has the same diameter as that of the optical fiber OF, the surface is in surface contact with the peripheral surface of the optical fiber (from a series of infinite line contacts). However, the formation of such an optical fiber accommodation hole cannot be realized by a conventional processing technique. This is not limited to the shape of the optical fiber housing hole of the ferrule, and it has been impossible in the prior art to produce a ferrule composed of a plurality of divided optical fiber holders. Therefore, a method for manufacturing a ferrule according to the present invention will be described in detail below.
[0020]
FIGS. 3A and 3B show an X-ray mask 10 for forming a ferrule having a cylindrical optical fiber accommodation hole. The X-ray absorption film 11 and the X-ray transmission film 12 are shown in FIG. Become. When the resist on the substrate 13 is exposed with X-rays using this X-ray mask 10 as in the step of FIG. 4, only the portion corresponding to the X-ray transmissive film 12 is exposed with X-rays to generate a resist exposure portion 14. . That is, the resist exposure portion 14 has a ferrule shape, and the non-exposure portion corresponding to the X-ray absorption film 11 has a ferrule mold shape. In the case of X-rays, PMMA or PTFE is used as a resist.
[0021]
At this time, in the X mask 10, the exposure mode is changed by changing the thickness of the X-ray absorption film 11, so that a part of the portion serving as the optical fiber accommodation hole is enlarged. This is due to the difference in the X-ray absorption value in the X-ray absorption film. The shape formed on the photosensitive resist is that the three-dimensional shape of the X-ray mask is enlarged and transferred to the photosensitive resist. Become. In this way, if a mask composed of an X-ray absorption film and an X-ray transmission film is used, a submicron shape can be easily created, and at the same time, the contrast between the absorber and the holding body becomes very good. The exposed resist surface can easily produce a mirror surface with a surface roughness of 0.1 μm or less and accuracy.
[0022]
Specifically, an extremely fine and highly accurate resist structure is produced by using an X-ray mask that maintains submicron accuracy, for example, an X-ray mask having a roundness of 0.1 μm and a pitch accuracy of 0.1 μm. I can do it. For example, as an X-ray mask, a polyimide film 75 μm as an X-ray transmission film is used by patterning Au as an X-ray absorber with a thickness of 50 to 60 μm, and the thickness of PMMA as a resist is set to 12 mm. A ferrule matrix having a fiber accommodation hole length of 12 mm can be manufactured by performing X-ray exposure, electrodepositing the entire formed resist with a Ni-Fe alloy to a height of 12 mm, and removing the resist. . If a molding die is produced by electroforming using this mother die, a ferrule can be produced from this die by resin molding with high accuracy. That is, a precise ferrule can be formed by combining photolithography using X-rays and a molding method using electroforming.
[0023]
Further, if the X-ray absorption film and the X-ray transmission film in the X-ray mask of FIG. 3 are reversed as the mask shape due to the difference in X-ray absorption value, the three-dimensional resist 21 as shown in FIG. I can get it. And if the resist 21 is formed on the conductive substrate 22, the metal mold | die 23 along the resist shape is obtained by performing electrodeposition from the conductive substrate 22. FIG.
[0024]
Here, an example of producing an X-ray mask for forming an optical fiber accommodation hole whose one end is enlarged in a tapered shape will be described with reference to FIG.
[0025]
First, a photosensitive resist 32 having a required thickness is applied on the substrate 31, the first photomask 33 is brought into close contact with the surface of the photosensitive resist 32, and the central axis is inclined by an angle θ of a taper portion formed as an X-ray mask. When the substrate 31 is rotated (see FIG. 7A), the photosensitive resist 32 is exposed in a bowl shape by the UV light incident from the opening 33a of the first photomask 33, and has a trapezoidal shape. The photosensitive portion 34a is generated (see FIG. 7B). The first photomask 33 may be off-contact as long as the first photomask 33 can be rotated while maintaining a relative position to the substrate 31.
[0026]
In order to generate a further cylindrical photosensitive region on the photosensitive portion 34a formed as described above, the exposure is performed again with the second photomask 35 having an opening 35a corresponding to the diameter of the cylinder disposed (FIG. 7 (c)). Thus, a photosensitive portion 34b having a shape in which a cone and a cylinder are combined is obtained (see FIG. 7D). If the resist portion not exposed is removed, the shape for transferring the tapered optical fiber accommodation hole is obtained. The resulting resist product can be formed on the substrate 31 (see FIG. 7E). Note that a photomask having a plurality of tapered cylinders can be formed by forming tapered cylinders at a plurality of locations by the same method. Further, if one side of the tapered cylinder is exposed on the entire surface, a tapered semi-cylinder is formed only on the non-exposed side, so that a shape like an optical fiber accommodation groove in the divided ferrule can be realized.
[0027]
When the split ferrule is created by combining the photolithography using X-ray as described above and the molding method using electroforming, an X-ray mask 40 as shown in FIG. 8 may be used. That is, assuming two holding bodies so as to divide the optical fiber housing hole of the ferrule into two parts, an X-ray absorption film 41a having a shape to which a creation having a shape corresponding thereto is transferred, and a frame shape surrounding the periphery The X-ray absorbing film 41b and the X-ray transmitting film 42 filling the gap are formed.
[0028]
If the photosensitive resist coated on the conductive substrate 51 with a sufficient thickness is irradiated with X-rays with the X-ray mask 40 interposed therebetween and developed, the same shape as that of one holding body which is a divided ferrule The resist creation 52a and a frame-shaped creation 52b surrounding the resist creation 52a appear. Thus, the void 53 formed between the resist products 52a and 52b can be used as a mold for forming a divided ferrule. If a metal is formed in the void 53 by electroforming, the mold for the divided ferrule is used as it is. Is obtained. By using the mold thus obtained, it is possible to easily mass-produce split ferrules (first holding body 60a and second holding body 60b) having excellent dimensional stability.
[0029]
Next, a specific example of assembling a ferrule containing an optical fiber using the first holding body 60a and the second holding body 60b will be described with reference to FIG.
[0030]
As shown in FIG. 11A, when the first holding body 60a and the second holding body 60b are completely separated, the first holding body 60a is set on the ferrule assembly jig 61, and the covering 62a is removed. The exposed optical fiber 62b is placed in the optical fiber housing groove of the first holding body 60a, and the tip surface of the optical fiber 62b and the tip of the first holding body 60a are abutted against the stopper surface 61a of the ferrule assembly jig 61. In this state, the second holding body 60b is covered, and the first holding body 60a and the second holding body 60b are integrated using the fastening band 63. That is, use a groove-shaped first holding body that substantially matches the outer periphery of the optical fiber, or a groove-shaped first holding body that can stably hold the optical fiber at a fixed position by two or more line contacts. As a result, the assembly can be performed without using an intervening material such as an adhesive. As a result, the work such as alignment is not required, and a quick and efficient optical fiber connection work can be realized.
[0031]
As shown in FIG. 11B, when the first holding body 60a and the second holding body 60b are temporarily assembled with a fastening band, after the optical fiber accommodation grooves of the first and second holding bodies 60a and 60b. The first holding body 60a and the first holding body 60a and the second holding body 60a are provided with an appropriate hinge structure at the rear ends of the first and second holding bodies 60a and 60b. The optical fiber 62b can be easily aligned in the optical fiber accommodation groove of the first holding body 60a without separating the two holding bodies 60b. Therefore, with the first holding body 60a set in the ferrule assembly jig 61, the second holding body 60b is lifted around the side with the enlarged diameter portion as an axis, the optical fiber 62b is inserted, and the tip surface of the optical fiber 62b The front end of the first holding body 60a is brought into contact with the stopper surface 61a of the ferrule assembly jig 61 and aligned. In this state, the second holding body 60b is closed, and in this state, the first holding body 60a and the first holding body 60a are closed. The two holders 60b may be firmly tightened and integrated.
[0032]
In addition, although the ferrule which formed the high-precision optical fiber insertion hole by the above-mentioned method can be assembled as an optical connector by the same method as the old one by keeping the shape that can be attached to the exterior member as it is, If the plating is thickened by electroforming plating, it takes too much time to deposit the metal, which increases the cost. Therefore, the minimum required part including the main part such as the optical fiber housing hole is used as a ferrule part. It is possible to form a ferrule shape that can be assembled to the exterior member by insert molding this metal ferrule part into a mold.
[0033]
Further, taking advantage of the method of the present invention that can realize a highly accurate three-dimensional shape, a guide pin insertion hole may be provided in the ferrule. That is, when creating a high-precision mold as described above, if a guide pin insertion hole is provided together with the optical fiber accommodation hole, when a metal ferrule is deposited from the mold by electroforming plating, Since the position dimensions of the optical fiber accommodation hole and the guide pin insertion hole are reproduced with high accuracy, the ferrules can be directly connected without being attached to the exterior member having the engagement / disengagement means as the connector.
[0034]
【The invention's effect】
As described above, according to the ferrule manufacturing method of the first aspect, the optical fiber is applied to the X-ray mask in which the three-dimensional shape of the optical fiber housing hole of the ferrule is formed by the X-ray absorption film and the X-ray transmission film. By exposing the photoresist applied on the substrate by irradiating X-rays from the formation direction of the accommodation hole, the three-dimensional shape of the X-ray mask that is enlarged in the X-ray irradiation direction is transferred to the photoresist, This is developed, the non-exposed portion is removed to form a ferrule male or female mold, a ferrule molding mold is created using this male or female mold, and the ferrule is molded with this mold Therefore, the shape and dimensions of the mask can be managed on the submicron order at the same time as the shape of the X-ray mask is transferred using X-ray exposure. Processing method It can perfectly ensure excellent dimensional stability remote. Therefore, it is possible to realize a fiber receiving hole with high accuracy so that the optical fiber core does not need to be adjusted separately, and as before, a ferrule can be assembled without using an adhesive or other inclusion, and the optical fiber connection Significant process innovation is possible. As a result, the construction technology related to optical fiber becomes easy, the construction cost can be greatly reduced, and the optical fiber can be laid down easily and inexpensively to the end of various equipment. Can greatly contribute to the establishment of social infrastructure. In addition, an optical fiber can be inserted by using an X-ray mask that has a three-dimensional shape formed by an X-ray absorbing film and an X-ray transmitting film so that one end of the optical fiber housing hole of the ferrule is tapered. It is possible to form a fiber accommodation hole having a guide function when performing high precision.
[0035]
According to the ferrule manufacturing method of claim 2, the three-dimensional shape corresponding to the first holding body and the second holding body, which are divided so as to bisect the optical fiber accommodation hole of the ferrule, is X Since each of the X-ray masks formed of the line absorption film and the X-ray transmission film is used to form the male type or the female type of the first holding body and the second holding body, it is possible to further accommodate the optical fiber. A ferrule that can be simplified can be manufactured.
[0036]
Further, according to the ferrule manufacturing method of the third aspect, two or more fiber support portions where the peripheral surface of the optical fiber comes into contact with each other in line contact appear in the optical fiber housing groove formed in the first holding body. (2) Each X-ray mask is formed so that the optical fiber receiving groove formed in the holding body has a shape in which one or more fiber support portions with which the peripheral surface of the optical fiber comes into contact in line contact appear. Therefore, the optical fiber can be stably held in the optical fiber accommodation hole formed by closing the first holding body and the second holding body.
[0037]
Further, the ferrule according to claim 4 is manufactured by the ferrule manufacturing method according to any one of claims 1 to 3, so that the optical fiber core does not need to be separately adjusted with high accuracy. The fiber accommodation hole can be realized.
[Brief description of the drawings]
FIG. 1 is an external perspective view of a ferrule including a first holding body and a second holding body.
FIG. 2A is a front view of a ferrule.
(B) It is the upper surface or bottom view of a ferrule.
(C) It is a rear view of a ferrule.
(D) It is a side view of a ferrule.
FIG. 3A is a top view of an X-ray mask for manufacturing ferrules.
(B) It is bb sectional drawing of Fig.3 (a).
FIG. 4 is an explanatory diagram of a resist creation process using an X-ray mask.
FIG. 5 is an external perspective view of a resist product.
FIG. 6 is a schematic cross-sectional view of a resist creation body and a ferrule mold.
FIG. 7 is an explanatory diagram of a manufacturing process of an X-ray mask for manufacturing a ferrule.
FIG. 8A is a top view of an X-ray mask for manufacturing a divided ferrule.
(B) It is bb sectional drawing of Fig.8 (a).
FIG. 9 is an external perspective view of a resist product of a divided ferrule.
FIG. 10 is an external perspective view of a divided ferrule.
FIG. 11 is an explanatory diagram showing an optical fiber mounting step on a split ferrule.
[Explanation of symbols]
OF optical fiber 1 ferrule 2a 1st holding body 2b 2nd holding body 3 optical fiber accommodation hole 3a optical fiber accommodation groove 3b optical fiber accommodation groove 4 optical fiber support part 5 expanded diameter part 10 X-ray mask 11 X-ray absorption film 12 X Line transmission film 13 Substrate 14 Resist exposure part

Claims (4)

  Photo coated on the substrate by irradiating the X-ray mask formed by the X-ray absorption film and the X-ray transmission film with the three-dimensional shape of the optical fiber accommodation hole of the ferrule by irradiating the X-ray from the formation direction of the optical fiber accommodation hole. By exposing the resist, the three-dimensional shape of the X-ray mask enlarged in the X-ray irradiation direction is transferred to the photoresist, developed, and the non-exposed portion is removed to remove the ferrule male or female. Forming a ferrule molding mold using this male mold or female mold, and manufacturing a ferrule using this mold,
  A ferrule manufacturing method using an X-ray mask having a three-dimensional shape formed by an X-ray absorbing film and an X-ray transmitting film so that one end of the optical fiber housing hole of the ferrule spreads in a tapered shape. Method.   X-ray mask in which a three-dimensional shape corresponding to a first holding body and a second holding body that are divided so as to bisect an optical fiber accommodation hole of a ferrule is formed by an X-ray absorption film and an X-ray transmission film The method for producing a ferrule according to claim 1, wherein each of the first and second holding bodies is used to form a male mold or a female mold.   Two or more fiber support portions where the peripheral surface of the optical fiber abuts in line contact appear in the optical fiber housing groove formed in the first holding body, and the optical fiber housing groove formed in the second holding body has the optical fiber in the optical fiber housing groove. 3. The ferrule manufacturing method according to claim 2, wherein each X-ray mask is formed so that one or more fiber support portions that come into contact with each other by line contact appear. Method.   The ferrule manufactured by the manufacturing method of the ferrule of any one of the said Claims 1-3.

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