JP2010072078A - Manufacturing method of optical waveguide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for easily and inexpensively manufacturing an optical waveguide that has a thin clad part covering the upper and lower part of a core and has flexibility. <P>SOLUTION: A laminated film 10 is prepared in which a core layer 14 for propagating light and cladding layers 12, 16 having a smaller refractive index than that of the core layer are alternately laminated and in which at least one side is the cladding layer, with the cladding layer 12 on the one side fixedly stuck to a dicing tape 20. The laminated film is cut in the thickness direction to the middle of the lowest cladding layer stuck to the dicing tape, forming a groove 18 and also the core part 14A. After the groove is filled with a liquefied polymer resin having a refractive index smaller than that of the core layer, the resin is hardened to form an imbedded cladding layer 24, The laminated film is cut in the thickness direction to below the lowest cladding layer together with the imbedded cladding layer in a manner that the parts 24A, 24B of the imbedded cladding layer remain, thereby forming the optical waveguide 30. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical waveguide manufacturing method.

  In recent years, the amount of data used in devices tends to increase due to higher functionality of notebook personal computers and mobile phones. In order to propagate light as a signal by transmitting and receiving data in these mobile devices, flexible type polymer optical waveguides having followability against twisting and bending such as flexible printed circuit boards used for electrical wiring have been proposed. (See Patent Document 1). In this flexible type polymer optical waveguide, the core through which light propagates and the clad provided around the core are both made of a material having a low bending elastic modulus such as a gel material. Have.

  In addition, as the performance of mobile devices increases, miniaturization progresses and the devices are mounted at a high density in the mobile devices. For example, in the slide mechanism, the distance D between the substrates is required to be 4 mm or less, and will be reduced to about 2 mm in the future. It is requested. There is a need for an optical waveguide having high flexibility even in repeated bending and stretching by a hinge mechanism or a slide mechanism.

As a method for easily producing a linear polymer optical waveguide, for example, a first layer serving as a cladding and a second layer (core layer) having a higher refractive index than the first layer are formed on a substrate. . A core part is formed by mechanically cutting and removing a part of the second layer with a dicing saw or the like, and then covering the core part with a material having a refractive index lower than that of the core part. The third layer (cladding layer) There has been proposed a method of forming an optical waveguide structure by forming (see Patent Document 2).
JP 2003-207659 A JP-A-8-286064

  SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a flexible optical waveguide with a thin and thin clad portion covering the top and bottom of a core in a simple and inexpensive manner.

The invention of claim 1 is a step of preparing a laminated film in which a core layer through which light propagates and a clad layer having a refractive index smaller than that of the core layer are alternately laminated, and at least one surface of which is the clad layer; The step of fixing the clad layer on one side of the laminated film to a dicing tape and fixing the laminated film in the thickness direction to the middle of the lowermost clad layer attached to the dicing tape to form a groove And forming the core part, filling the groove with a liquid polymer resin having a refractive index smaller than that of the core layer, and then curing to form an embedded cladding layer, and the laminated film, An optical waveguide is formed by cutting in the thickness direction to the bottom of the lowermost clad layer together with the buried clad layer so that a part of the buried clad layer remains. And that step is a method of manufacturing an optical waveguide, which comprises a.
The invention according to claim 2 is characterized in that the refractive index of the polymer resin forming the buried cladding layer is smaller than the refractive index of the cladding layer constituting the laminated film. It is a manufacturing method.
According to a third aspect of the present invention, the thickness of the blade used for cutting the laminated film in the step of forming the core portion is 20 μm or more than the thickness of the blade used for cutting the embedded cladding layer in the step of forming the optical waveguide. 3. The optical waveguide manufacturing method according to claim 1, wherein the optical waveguide is thick.
According to a fourth aspect of the present invention, an ultraviolet peelable dicing tape is used as the dicing tape, and a thermosetting resin is used as the polymer resin for forming the embedded cladding layer, or a heat peelable resin as the dicing tape. 4. The method of manufacturing an optical waveguide according to claim 1, wherein a dicing tape is used, and an ultraviolet curable resin is used as a polymer resin for forming the buried cladding layer. 5. is there.

According to the first aspect of the present invention, a thin clad portion can be formed by cutting the buried clad layer with a constant width, and the thickness of the upper and lower clad portions is larger than that in the case where this configuration is not provided. However, a thin and flexible optical waveguide can be manufactured easily and inexpensively.
According to the second aspect of the present invention, it is possible to easily and inexpensively manufacture an optical waveguide having a higher optical confinement effect when bent compared to the case where the present configuration is not provided.
According to the third aspect of the invention, the number of cuttings can be reduced as compared with the case where the present configuration is not provided, and alignment and cutting when cutting the embedded cladding layer are facilitated, and the optical waveguide has flexibility. Can be manufactured more simply and at a lower cost.
According to the invention of claim 4, compared to the case without this configuration, when the embedded cladding layer is formed by curing the polymer resin, the dicing tape does not peel and the occurrence of undulation is suppressed. Therefore, the subsequent buried cladding layer can be cut more easily, and the thickness of the upper and lower cladding portions can be reduced, and a more uniform optical waveguide can be manufactured easily and inexpensively.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Note that members having substantially the same function and action are given the same reference numerals throughout the drawings as appropriate, or the reference numerals are omitted, and repeated descriptions are omitted as appropriate.

Prior to the completion of the present invention, the present inventors conducted the following examination.
First, since the optical waveguide disclosed in Patent Document 1 is made of a gel-like flexible material, there is a problem at the time of contact after mounting.
On the other hand, a dicing saw as disclosed in Patent Document 2 is used in order to produce an optical waveguide with a thin cladding layer having a bending durability in the bending direction, using a material that does not have a problem with contact after mounting. When producing an optical waveguide, the flatness of the sample table of the dicing saw, the nonuniformity of the dicing tape thickness, the nonuniformity of the blade height, changes in the blade shape, etc. In general, the core portion is formed by cutting (half-cutting) a part of the lower cladding layer.

By the way, since the flexibility of the polymer optical waveguide depends on the total thickness of the waveguide, it is advantageous that the total thickness is as thin as possible, and the total thickness is often 100 μm or less. The required core diameter of the optical waveguide is determined by the optical system used, and the thickness of the core layer is restricted. Therefore, the total thickness of the entire waveguide is determined by the thicknesses of the upper and lower cladding layers.
However, the thinner the clad layer, the poorly formed core due to insufficient cutting depth even when half-cutting is performed, or the lower clad layer is completely cut, that is, full cut occurs, resulting in a particularly high yield. There is a problem that it is not suitable for large-scale production.

  Therefore, the present inventors formed a cutting groove in a laminated film used for manufacturing an optical waveguide, and after forming an embedded cladding layer in the groove, the embedded cladding layer was cut further finely to obtain upper and lower cladding layers. By doing so, it has been found that an optical waveguide having a flexible structure with thin upper and lower clad portions can be easily and inexpensively manufactured.

<First Embodiment>
1A to 1D schematically show a manufacturing process of an optical waveguide according to the first embodiment. FIG. 2 schematically shows a cross section of an optical waveguide manufactured according to this embodiment.
First, a laminated film 10 in which a core layer 14 through which light propagates and cladding layers 12 and 16 having a refractive index smaller than that of the core layer 14 are alternately laminated and at least one surface is the cladding layer 12 is prepared.
In order to exhibit optical characteristics as an optical waveguide, each of the cladding layers 12 and 16 needs to be made of a material having a refractive index lower than that of the core layer 14, and in particular, in order to secure a refractive index difference from the optical waveguide core 14A, The relative refractive index difference is 1% or more, preferably 3% or more.
The specific material constituting the laminated film 10 is not particularly limited as long as the predetermined refractive index difference between the clad layers 12 and 16 and the core layer 14 can be set. For example, an alicyclic olefin film and an acrylic film An epoxy film, a polyimide film, or the like is used.

The method for producing the laminated film 10 is not particularly limited. For example, a lower clad polymer layer (first clad layer) 12, a core polymer layer 14, an upper clad are formed on a flat support substrate such as glass or silicon. The laminated polymer film 10 is produced by sequentially laminating the polymer layer (second clad layer) 16 for use. The method of laminating the layers 12, 14, and 16 is not particularly limited as long as they are integrally laminated so that no peeling occurs between the layers 12, 14, and 16, and known methods such as a laminating method and a spin coating method are known. The method is adopted.
The number of clad layers and core layers is not limited. For example, when an optical waveguide having a plurality of core portions is manufactured, a laminated film in which a plurality of core layers are alternately laminated with a clad layer is prepared. Good.

The thickness of each layer 12, 14, and 16 is not specifically limited, What is necessary is just to select according to the use etc. of the optical waveguide 30 to produce.
For example, the thickness (core diameter) of the core layer 14 may be selected according to the optical system connected to the optical waveguide 30 to be manufactured.
On the other hand, since the clad layers 12 and 16 finally constitute the clad portions 12A and 16A positioned on the left and right of the core 14A of the optical waveguide 30, the processing accuracy of the dicing saw used for forming the cutting groove 18 and the optical waveguide What is necessary is just to select according to the space etc. in which 30 is arrange | positioned.
In addition, the following are mentioned as what controls the cutting depth of the laminated film 10 by a dicing saw. For example, the height accuracy of the blade 22 of the dicing saw is ± 0.5 μm, the flatness of the sample table of the dicing saw is ± 3 μm, the thickness non-uniformity of the dicing tape 20 is ± 3 μm, and the non-uniformity of the blade 22 is The change of the blade shape is ± 3 μm and the change of the blade shape is ± 2 μm. In order to manufacture with a higher yield, it is desirable that the lowermost cladding layer 12 has a thickness of 25 μm or more, considering a margin of about 3 μm.

Although the total thickness of the laminated film 10 is not particularly limited, the thickness of the laminated film 10 corresponds to the width W of the optical waveguide 30 to be finally produced. Considering that the distance D between substrates is required to be 4 mm or less in a recent slide mechanism, the total thickness of the laminated film 10 is preferably 4 mm or less.
Further, when the blade diameter is increased, there is a possibility that a phenomenon that the optical waveguide 30 formed by the full cut falls down in the step of performing the full cut to the bottom of the lowermost clad layer 12 (FIG. 1D). . Therefore, in order to improve the production yield, the ratio between the total thickness of the laminated polymer film 10 and the thickness T of the optical waveguide 30 to be produced is preferably about 10: 1 to 80: 1, and 10: 1 to 30: 1. The degree is more desirable.

As shown in FIG. 1 (A), the clad layer 12 on one side of the laminated film 10 is attached to a dicing tape 20 and fixed.
As will be described later, the dicing tape 20 is peeled off from the curing of the polymer resin in consideration of the characteristics of the polymer resin used for forming the buried cladding layer (third cladding layer) 24. It is preferable to select one capable of For example, an ultraviolet peelable or heat peelable dicing tape is used.

Next, as shown in FIG. 1B, the laminated film 10 is cut in the thickness direction to the middle of the lowermost clad layer 12 attached to the dicing tape 20 to form the groove 18 and the core portion 14A. Form.
Cutting is performed at a cutting depth that allows the lowermost core layer 14 to be removed from the upper clad layer 16 of the laminated film 10 (a degree in which a part of the lower clad layer 12 is cut). I do. In addition, since the core layer remaining between the cutting grooves 18 becomes the core portion 14A through which light propagates, the cutting grooves 18 are formed in accordance with the thickness of the core layer 14 and the optical system to which the optical waveguide 30 to be manufactured is connected. What is necessary is just to set a pitch.

Next, as shown in FIG. 1C, after filling the groove 18 with a liquid polymer resin having a refractive index smaller than that of the core layer 14, the buried cladding layer 24 is formed by curing the resin.
The curable resin for forming the buried cladding layer 24 is in a liquid state, and is poured into the cutting groove 18 to be filled and then cured by applying an external stimulus, such as radiation curable, electron beam curable, or heat. A curable resin is used. In any case, since the curable resin filled in the cutting groove 18 is the upper and lower clad portions 24A and 24B of the optical waveguide 30, a resin having a refractive index smaller than that of the core layer 14 is used.

The resin that fills the cutting grooves 18 to form the embedded cladding layer 24 in this way may be made of the same material as the cladding layers 12 and 14 constituting the laminated film 10, for example. It is preferable to use a material having a refractive index smaller than that of the layers 12 and 14.
The buried cladding layer 24 made of a curable resin is partially cut later to reduce the width, and constitutes upper and lower cladding portions 24A and 24B in the optical waveguide 30 as shown in FIG. Such an optical waveguide 30 in which the upper and lower cladding portions 24A and 24B are thin is more likely to bend in the thickness T direction (vertical direction) than in the width W direction, and is required to have a light confinement effect in the thickness direction. Therefore, if the refractive index of the resin constituting the buried cladding layer 24 is smaller than the refractive index of the cladding layers 12 and 16 constituting the laminated film 10, the polymer optical waveguide has a higher optical confinement effect when bent in the vertical direction. Is obtained.

  For example, when the dicing tape has ultraviolet releasability, if an ultraviolet curable resin is used for forming the embedded cladding layer, peeling between the laminated film 10 and the dicing tape 20 is likely to occur due to exposure for resin curing. Even if the film 10 peeled off from the dicing tape 20 is attached to the dicing tape 20 again for a subsequent separation step, waviness occurs in the embedded cladding layer 24 formed by curing the resin, and the upper and lower sides of the optical waveguide 30 are There is a possibility that the accuracy of the thickness adjustment of the clad portions 24A and 24B will decrease. Therefore, it is desirable that the embedded clad layer forming resin and the dicing tape 20 be combined such that the curing of the resin and the peeling of the dicing tape 20 do not occur simultaneously. For example, when an ultraviolet curable resin is used as the polymer resin for forming the buried cladding layer 24, a heat-peelable dicing tape is used, and when a thermosetting resin is used, an ultraviolet-peelable dicing tape is used. preferable.

  It should be noted that a thermosetting resin and a heat-peelable dicing tape in which the temperature at which the polymer resin forming the buried cladding layer 24 is cured and the temperature at which the dicing tape 20 is peeled off may be used. An ultraviolet curable resin and an ultraviolet detachable dicing tape may be used such that the wavelength at which the polymer resin forming the resin is different from the wavelength at which the dicing tape 20 is peeled off.

Next, as shown in FIG. 1D, the laminated film 10 is cut in the thickness direction to the bottom of the lowermost cladding layer 12 together with the embedded cladding layer 24 so that a part of the embedded cladding layer 24 remains. To do.
For example, using the blade 22 used when forming the cutting groove 18 in the laminated film 10, the position is shifted from the groove 18 filled with the cladding material in FIG. 1C by a length shorter than the width of the groove 18. The laminated film 10 is cut to a depth at which the tip of the blade 22 reaches the dicing tape 20. Thereby, a part of the embedded cladding layer 24 is cut and the laminated film 10 is separated. Then, a part of the two buried clad layers 24 sandwiching the core portion 14A is cut and full cut to the lower clad layer 12 to form one optical waveguide.

  In such a separation step, the portions 24A and 24B of the embedded cladding layer remaining on both sides of the core portion 14A after cutting constitute the upper and lower cladding portions 24A and 24B of the optical waveguide 30. The width (thickness) of the embedded claddings 24A and 24B to be left may be determined according to the use of the optical waveguide 30, the space in which the optical waveguide 30 is disposed, etc., but in this embodiment, based on the processing accuracy of the dicing saw, It is also possible to process the residual width of the buried cladding layer, that is, the thickness of the upper and lower cladding portions 24A and 24B of the optical waveguide 30 to 10 μm or less. If the thickness of the upper and lower clad portions 24A and 24B is 10 μm or less, the thickness T of the entire optical waveguide 30 becomes extremely thin, and an optical waveguide having high flexibility can be obtained. The thicknesses of the clad portions 24A and 24B can be adjusted more accurately by using the end portion of the laminated film 10 as a reference and controlling the movement amount of the blade 22 from the reference.

  After cutting, the optical waveguide 30 is peeled from the dicing tape 20 by heating to a predetermined temperature in the case of a dicing tape that is externally stimulated, for example, heat peelable. In the case of an ultraviolet peelable dicing tape, the optical waveguide 30 is peeled off by irradiating with ultraviolet rays. Thereby, the optical waveguide 30 as shown in FIG. 2 is obtained. In the optical waveguide 30 thus obtained, since the upper and lower cladding portions 24A and 24B are constituted by the embedded cladding layers 24A and 24B cut in the separation step (FIG. 1D), the upper and lower cladding portions 24A and 24B are formed. The thickness of 24B is thin, and the optical waveguide is highly flexible.

<Second Embodiment>
FIG. 3 schematically shows a step of cutting (full cut) under the lower clad layer 12 together with a part of the clad material filled in the cutting groove in the optical waveguide manufacturing process according to the second embodiment.
In the second embodiment, the laminated film 11 having the same configuration as that of the first embodiment is attached to the dicing tape 20 and fixed, and then the laminated film 11 is cut in the thickness direction to the middle of the lowermost cladding layer 12. . Here, the laminated film 11 is cut at regular intervals to form the core portion 14, and the buried cladding layer 24 is formed in the cut groove. Since the process until the cutting groove is filled with a liquid clad material (polymer resin) and cured is basically the same as in the first embodiment, description thereof is omitted.

  After forming the embedded cladding layer 24, a blade 32 having a thickness smaller than the width of the embedded cladding layer 24 is used, and the center of the blade 32 is aligned with the center of the embedded cladding layer 24 until the cutting depth reaches the dicing tape 20. A cutting groove 38 is formed. Thus, by cutting the central portion of the embedded cladding layer 24 to form the cutting groove 38 and cutting the laminated film 11, parts 24 </ b> A and 24 </ b> B of the embedded cladding layer 24 remain on both sides of the blade 32. At the same time, an optical waveguide is formed. The portions 24A and 24B remaining on the left and right sides of the core portion 14 by cutting the buried cladding layer 24 constitute upper and lower cladding portions of the optical waveguide.

  The thickness of the blade 22 used for cutting the laminated film 11 in the step of forming the core portion 14A and the thickness of the blade 32 used for cutting the embedded cladding layer 24 in the step of forming the optical waveguide are above and below the optical waveguide to be manufactured. What is necessary is just to select according to the thickness etc. of clad part 24A, 24B. If the difference between the thicknesses of these two types of blades 22 and 32 is too small, positions for leaving portions 24A and 24B of the embedded cladding layer 24 on both sides of the blade 32 when cutting the embedded cladding layer 24, respectively. High accuracy is required for alignment and cutting, which may lead to a decrease in productivity and a decrease in yield, such as a clad layer not being formed on one side of the blade 32. Therefore, the thickness of the blade 22 used when the laminated film 11 is cut to form the core portion 14A is 20 μm or more thicker than the thickness of the blade 32 used when the buried cladding layer 24 is cut to form the optical waveguide. Is preferred.

  On the other hand, if the difference between the thicknesses of the two types of blades 22 and 32 is too large, the thickness of the remaining buried claddings 24A and 24B becomes unnecessarily large, leading to a decrease in yield, and a single buried cladding layer 24 is formed several times. Although it is possible to make a thin layer by cutting into two parts, the productivity is lowered. Therefore, the difference in thickness between the two types of blades 22 and 32 is preferably 0.1 mm or less.

  Even when the central portion of the buried cladding layer 24 is cut with the blade 32 having a thickness smaller than the width of the buried cladding layer 24 as described above, the thickness of the buried cladding layers 24A and 24B remaining on both sides of the blade 32 can be reduced. In order to make the adjustment, the movement amount of the blade 32 may be controlled from the end of the laminated film 11 as a reference.

  In the present embodiment, in the second and subsequent cuttings, one optical waveguide is formed by one cutting, and the number of times of cutting is halved compared to the first embodiment, and the optical film is manufactured from one laminated film 11. Since the number of optical waveguides increases, an optical waveguide having high flexibility is manufactured at a lower cost.

<Third Embodiment>
You may employ | adopt a manufacturing process as shown to FIG. 4 (A)-(D). In this embodiment, the laminated film 13 in which the clad layer 12 and the core layer 14 are laminated one by one is attached and fixed to the dicing tape 20 (FIG. 4A), and the laminated film 13 is laminated in the thickness direction. The core part 14A is formed together with the cutting groove 48 (FIG. 4B). Next, a liquid polymer resin to be a cladding material is filled in the cutting groove 48 and applied to the core layer 14 and cured (FIG. 4C). Then, the optical waveguide is cut by cutting in the thickness direction from the upper clad layer 25 to the lower clad layer 12 together with the buried clad layer 44 so that a part of the buried clad layer 44 remains (FIG. 4D )). Even with such a method, the thickness of the clad portions 44A and 44B positioned above and below the core portion 14A is small, and an optical waveguide having high flexibility is easily and inexpensively manufactured.

  Also in this case, the cutting grooves 48 are formed at regular intervals, and in the separation step (FIG. 4D), as shown in FIG. 3, the width is smaller than the width of the cutting grooves 48 (embedded cladding layer 44). By cutting the central portion of the buried cladding layer 44 using the blade 32, the number of optical waveguides manufactured from one laminated film 13 is increased, and an optical waveguide having high flexibility is manufactured at a lower cost. The

Hereinafter, an example is given and it demonstrates more concretely. However, these examples do not limit the present invention.
<Example 1>
According to the method for manufacturing an optical waveguide according to the second embodiment, an optical waveguide was manufactured as follows.
Each layer is laminated so that a core layer (ultraviolet curable epoxy material: refractive index 1.58) is sandwiched between upper and lower cladding layers (ultraviolet curable epoxy material: refractive index 1.53). A three-layer film was produced. The thickness of the upper cladding layer is 200 μm, the thickness of the core layer is 50 μm, and the thickness of the lower cladding layer is 200 μm.
The lower clad layer side of this laminated film was attached to a heat-peelable dicing tape (manufactured by Nitto Denko Corporation, trade name: Riva Alpha, thickness: 180 μm).

A blade having a thickness of 0.12 mm was attached to the dicing saw, and a groove was cut at a predetermined pitch so that the lower end of the blade was 190 μm from the lowermost surface of the lower clad layer of the laminated film. The pitch between the grooves at this time is 170 μm.
Next, an ultraviolet curable epoxy material (refractive index of 1.53) was filled in the cut groove as an embedded clad and cured by ultraviolet irradiation.

Next, a blade having a thickness of 0.1 mm was attached to the dicing saw, and the center of the embedded cladding where the groove was backfilled was cut as a step of full-cutting the lowermost cladding layer. By thus cutting the embedded clad with the blade, clad layers (thickness: 10 μm) were formed on the left and right sides of the blade, respectively.
Then, after shaping into a 10 cm long strip, it was heated to 90 ° C. and peeled off from the dicing tape. As a result, 470 1-channel optical waveguides having a width of 0.5 mm, a thickness of 70 μm, a length of 10 cm, and a core diameter of 50 μm were produced.
Ten optical fibers were selected from the obtained optical waveguides, bent at 360 degrees with a radius of 1 mm, and measured for insertion loss. The average was 1.3 dB.

<Example 2>
According to the method for manufacturing an optical waveguide according to the first embodiment, an optical waveguide was manufactured as follows.
A three-layer film was produced in the same manner as in Example 1, and after the groove forming step, the cutting groove was filled with a clad material and cured.
Here, a blade having a thickness of 0.12 mm was used without replacing the blade, and the left and right sides of the core were fully filled up to the lowermost clad layer so that part of the buried clad layer constituted the clad layer (thickness: 10 μm). The process to cut is performed.
Then, after shaping into a 10 cm long strip, it was heated to 90 ° C. and peeled off from the dicing tape. Thereby, 260 1-channel optical waveguides having a width of 0.5 mm, a thickness of 70 μm, a length of 10 cm, and a core diameter of 50 μm were produced.
Ten optical fibers were selected from the obtained optical waveguides, bent at 360 degrees with a radius of 1 mm, and measured for insertion loss. The average was 1.3 dB.

<Example 3>
A three-layer film was prepared in the same manner as in Example 1, and the dicing tape was changed to an ultraviolet-peelable dicing tape to attach a laminated film. Next, the process is performed up to the groove forming process in the same manner as in Example 1, and after filling the groove with a thermosetting epoxy material (refractive index 1.52) and curing, the full length is cut to the lowermost cladding. Shaped into a 10 cm strip.
Subsequently, 470 1-channel optical waveguides having a width of 0.5 mm, a height of 70 μm, and a length of 10 cm were produced by irradiating with ultraviolet rays and peeling from the dicing tape.
Ten optical fibers were selected from the obtained optical waveguides, bent at 360 degrees with a radius of 1 mm, and measured for insertion loss. The average was 1.2 dB.

<Example 4>
Except for changing the thicknesses of the upper and lower cladding layers, the core layer (ultraviolet curable epoxy material: refractive index: 1.3) is provided between the cladding layers (ultraviolet curable epoxy material: refractive index: 1.53), as in Example 1. 58) were laminated so as to produce a 11 cm × 11 cm three-layer film. The thickness of the upper cladding layer is 20 μm, the thickness of the core layer is 50 μm, and the thickness of the lower cladding layer is 20 μm. The lower clad layer side of this laminated film was attached to a heat-peelable dicing tape (thickness: 180 μm).

A blade having a thickness of 0.12 mm was attached to the dicing saw, and a groove was cut at a predetermined pitch so that the lower end of the blade came to a position of 10 μm from the bottom of the lower clad layer of the laminated film. The pitch between the grooves at this time is 170 μm.
The part where the lower clad layer became a full cut was generated due to the error of the cutting depth, and when the groove was filled with an ultraviolet curable epoxy material (refractive index 1.53) and cured, it was adhered to the dicing tape. Therefore, of the 470 optical waveguides formed on the dicing tape, there were 160 that could not be peeled even when heated, but 310 were peeled from the dicing tape to obtain optical waveguides.

<Example 5>
A three-layer film having the same film configuration as in Example 1 was prepared, and the lower clad layer side was attached to an ultraviolet-peelable dicing tape (thickness: 180 μm).
Groove formation was also performed in the same manner as in Example 1, and after filling the cut groove with an ultraviolet curable epoxy material (refractive index 1.53), irradiation with ultraviolet light cured the epoxy material and peeled off the dicing tape. When the film was applied again to the UV-peelable dicing tape, waviness occurred in the film. Next, when part of the embedded cladding layer was cut and the film was fully cut to separate each optical waveguide, the blade contacted a part of the core, and 250 of the 470 optical waveguides were poorly manufactured. However, 220 good optical waveguides were obtained.

  The present invention is not limited to the above embodiments and examples, and may be modified as appropriate. For example, the number of core portions in the optical waveguide, the distance between the core portions, and the like are not limited, and may be formed as required.

It is a figure which shows roughly the manufacturing process of the optical waveguide which concerns on 1st Embodiment. (A) A process of attaching a three-layer laminated film to a dicing tape (B) A process of forming a groove and a core part (C) A process of forming an embedded cladding layer (D) Cutting to the lower cladding layer together with the embedded cladding layer ( Full cut) It is a figure which shows schematically the structure of the optical waveguide obtained by the method which concerns on 1st Embodiment. In the manufacturing process of the optical waveguide which concerns on 2nd Embodiment, it is a figure which shows roughly the process cut | disconnected (full cut) to the lower clad layer with a part of clad material with which the cutting groove was filled. It is a figure which shows schematically the manufacturing process of the optical waveguide which concerns on 3rd Embodiment. (A) A process of attaching a two-layer laminated film to a dicing tape (B) A process of forming a groove and a core part (C) A process of forming an embedded cladding layer and an upper cladding layer (D) A lower cladding layer together with an embedded cladding layer Cutting to the bottom (full cut)

Explanation of symbols

10, 11 Laminated film 12 Lower clad layer 12A Clad part 14 Core layer 14A Core part 16 Upper clad layer 16A Clad part 18 Groove 20 Dicing tape 22 Blade 24 Embedded clad layers 24A and 24B Clad part 25 Upper clad layer 26 Cutting groove 32 Blade 38 Cutting Groove 44 Embedded Cladding Layers 44A, 44B Clad Portion 48 Cutting Groove 50 Cutting Groove

Claims (4)

A step of preparing a laminated film in which a core layer in which light propagates and a clad layer having a refractive index smaller than that of the core layer are alternately laminated, and at least one surface of which is the clad layer;
Affixing the single-sided cladding layer of the laminated film to a dicing tape and fixing,
Cutting the laminated film in the thickness direction to the middle of the lowermost clad layer attached to the dicing tape to form a groove and forming a core part;
Forming a buried cladding layer by filling the groove with a liquid polymer resin having a refractive index smaller than that of the core layer, followed by curing;
Cutting the laminated film in the thickness direction to the bottom of the lowermost clad layer together with the buried clad layer so that a part of the buried clad layer remains, and forming an optical waveguide;
A method for manufacturing an optical waveguide, comprising:   2. The method of manufacturing an optical waveguide according to claim 1, wherein a refractive index of the polymer resin forming the embedded cladding layer is smaller than a refractive index of a cladding layer constituting the laminated film.   The thickness of the blade used for cutting the laminated film in the step of forming the core portion is 20 μm or more thicker than the thickness of the blade used for cutting the embedded cladding layer in the step of forming the optical waveguide. Item 3. A method for manufacturing an optical waveguide according to Item 1 or Item 2.   Using an ultraviolet peelable dicing tape as the dicing tape, and using a thermosetting resin as the polymer resin forming the embedded cladding layer, or using a heat peelable dicing tape as the dicing tape, and The method for manufacturing an optical waveguide according to any one of claims 1 to 3, wherein an ultraviolet curable resin is used as the polymer resin for forming the buried cladding layer.

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