JP2005266119A - Method for manufacturing photoelectric wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a photoelectric wiring board capable of easily forming an optical waveguide penetrating an electric wiring board and suppressing light propagation loss in the optical waveguide. Furthermore, the present invention provides a method for manufacturing a photoelectric wiring board capable of improving the coupling efficiency between a light receiving element and an optical waveguide.
SOLUTION: A step of forming wiring on the surface of the substrate, a step of removing a part of the substrate so as to have a desired shape and size and forming a through hole, and a clad protrusion and a first cladding of the optical wiring A photoelectric wiring substrate comprising: a step of forming simultaneously, a step of simultaneously forming a core protrusion and a core of an optical wiring, and a step of forming an optical path changing means on the core; and a step of forming a second cladding of the optical wiring. Production method.
[Selection] Figure 1

Description

  The present invention relates to a method of manufacturing a photoelectric wiring board having an optical wiring by an optical waveguide on an electric wiring board.

  As the performance of microprocessors is improved by several Gbit / s, it has become difficult to realize large-capacity transmission due to the influence of electromagnetic noise and the like in wiring using conventional electrical wiring. Therefore, in recent years, a method for producing an optical wiring that is not affected by, for example, electromagnetic noise using an optical waveguide and increasing the transmission capacity has been actively studied.

  As a method for manufacturing a photoelectric wiring board having an optical wiring by an optical waveguide on an electric wiring board as described above, a method disclosed in, for example, Patent Document 1 is conventionally known. A method for manufacturing the optical / electrical wiring board (photoelectric wiring board) described in Patent Document 1 will be described below with reference to FIGS. FIGS. 10A to 10E are diagrams showing the steps of the conventional method for manufacturing an optical / electrical wiring board described in Patent Document 1, and are arranged in the order of execution. FIG. 11 shows an optical / electrical wiring board formed by forming the mirror 106 and the lens 107 after being manufactured through the respective steps shown in FIG.

  First, as shown in FIG. 10A, a 100 μm through-hole (through hole) 108 is opened with a laser in an electrical wiring substrate 101 which is a 125 μm-thick polyimide substrate having electrical wiring and pads 110.

  Next, as shown in FIG. 10 (b), the inner surface of the through hole (through hole) 108 of the electric wiring board 101 is filled with a vertical clad 103b which is a fluorinated epoxy resin adjusted to a refractive index of 1.52, for example. And cured at 200 ° C.

  Next, as shown in FIG. 10C, the optical wiring layer 102 is formed on the surface of the electric wiring substrate 101 where the pads are not formed. First, a fluorinated epoxy resin adjusted to have a refractive index of 1.52 is applied. Thereafter, the applied fluorinated epoxy resin is cured at 200 ° C., for example, with a film thickness of 20 μm, and a part of the horizontal cladding is formed.

  Next, a fluorinated epoxy resin adjusted to have a refractive index of 1.53 is applied, cured at 200 ° C. to a thickness of 8 μm, and a horizontal waveguide is formed by dry etching according to a conventional method. The width of the horizontal waveguide at this time is, for example, 8 μm. Further, a fluorinated epoxy resin having a refractive index of 1.52 is applied to the horizontal waveguide. Thereafter, the applied fluorinated epoxy resin is cured, for example, with a film thickness of 20 μm, and the remaining portion of the horizontal cladding is formed. With the above configuration, the optical wiring layer 102 is completed (FIG. 10C).

  Subsequently, as shown in FIG. 10 (d), the excimer laser has a central portion of the through hole (through hole) 108 filled with the vertical cladding, and has a diameter larger than the inner diameter of the through hole (through hole) 108. A through hole 108 having a small inner diameter is opened. As a result, the side surface of the through hole (through hole) 108 is covered with the vertical cladding.

  Next, as shown in FIG. 10E, the through hole 108 of the electric wiring board 101 is filled with a fluorinated epoxy resin made of the same material as the horizontal waveguide. Then, the vertical waveguide can be formed by curing the fluorinated epoxy resin at 200 ° C.

  The mirror 106 may be formed on the optical / electrical wiring board after the above processes. The mirror 106 is formed at a position where the horizontal waveguide and the vertical waveguide intersect with a surface of 45 degrees with respect to the surface of the electric wiring substrate 101 by dicing using a 90-degree blade or oblique etching of RIE. . The mirror 106 may be a mirror 106 having a metal reflective film by sputtering, vapor deposition, or the like. The mirror 106 is formed on the basis of an alignment mark (not shown) that the electric wiring substrate 101 has on the adhesive surface with the optical wiring layer 102.

Further, a lens 107 may be provided on the end face of the vertical waveguide located on the electric wiring board 101. The lens 107 is provided to facilitate optical axis alignment between the optical / electrical wiring board and the light receiving element mounted on the optical / electrical wiring board. The light propagating through the optical waveguide is condensed by the lens 107, whereby high-precision optical axis alignment can be realized. The lens 107 has a low Tg or a low melting point and the same refractive index as that of the vertical waveguide. A rectangular pattern of photosensitive acrylic resin is formed on the exposed portion of the optical through hole and melted at 200 ° C. Can be formed. In this way, an optical / electrical wiring board as shown in FIG. 11 can be manufactured.
WO 01/001176 pamphlet

  However, the conventional method for manufacturing an optical / electrical wiring board described in Patent Document 1 described above has the following problems.

  That is, when forming the optical waveguide in the hole formed in the electrical wiring board, after filling the clad, the laser is irradiated to form a hole in the center of the clad, and then the core is filled. (FIGS. 10 (d) and 10 (e)), the removed clad material remains as wrinkles in the periphery, and there is a problem that newly requires a process of removing with chemicals to remove the wrinkles. It was. Further, the inner surface of the hole becomes uneven due to laser irradiation, and thereafter, there is a problem that the propagation loss of light increases at the core / cladding interface even when the core is formed and the optical waveguide is formed.

  In the method for manufacturing an optical / electrical wiring board described in Patent Document 1, a vertical core region is formed by irradiating a laser to form a vertical optical waveguide with respect to a horizontal optical waveguide. doing. However, this manufacturing method has a problem in that a boundary portion is formed between the optical waveguides in the vertical direction and the horizontal direction, and the propagation loss of light increases at the boundary portion.

  Further, when a lens is formed as necessary, since it is newly formed on the optical waveguide, there is a problem that light propagation loss occurs at the interface between the lens and the optical waveguide. In addition, since the lens can be formed only on the same surface as the electric wiring board, the distance between the light emitting surface of the light emitting element and the light receiving surface of the light receiving element cannot be controlled, and the optical coupling efficiency is optimized. There is a problem that the height of the light emitting element and the light receiving element cannot be adjusted as necessary.

  As described above, in the conventional method of forming an optical waveguide by laser irradiation, light is emitted at various parts such as the interface between the core and the cladding, the boundary between the vertical and horizontal optical waveguides, and the boundary between the lens and the optical waveguide. There is a problem that the propagation loss of the device becomes large. Such a large propagation loss of light becomes a big problem in realizing optical wiring. That is, in order to realize the optical wiring, it is necessary to increase the light output of the light emitting element in accordance with the minimum amount of light received necessary for reception of the light receiving element, which places a heavy load on the light emitting element. Further, since there is no allowance for the amount of light, there is no degree of freedom in designing optical wiring. Therefore, considering the long-term stability without degrading the light-emitting element, and taking into account the freedom in designing the optical wiring, the propagation loss in the optical waveguide is suppressed as much as possible, and the efficient optical wiring It is necessary to.

  The present invention has been made to solve the above-described problems, and the object of the present invention is to easily form an optical waveguide that penetrates the electric wiring board and to suppress light propagation loss in the optical waveguide. It is providing the manufacturing method of a photoelectric wiring board. Another object of the present invention is to provide a method of manufacturing a photoelectric wiring board that can improve the coupling efficiency between the light receiving element and the optical waveguide.

  The photoelectric wiring board manufacturing method of the present invention includes a step of forming electrical wiring on the surface of the substrate, a step of removing a part of the substrate so as to have a desired shape and size, and forming a through hole, and a clad protrusion. And a step of simultaneously forming a first cladding of the optical wiring, a step of simultaneously forming the core protrusion and the core of the optical wiring, further forming an optical path changing means on the core, and a step of forming the second cladding of the optical wiring. It is characterized by including.

  In the method of manufacturing a photoelectric wiring substrate according to the present invention, in the step of removing a part of the substrate so as to have the desired shape and size and forming the through hole, the through hole is formed in a ring shape provided in a mold. It is preferable to form by punching with a through-hole forming part, and to use the mold as a holder for the substrate in a step after the step.

  In the method for manufacturing a photoelectric wiring board according to the present invention, the step of simultaneously forming the clad protrusion and the first clad of the optical wiring may include a step of forming a desired clad protrusion on the through hole forming portion provided in the mold. The step of forming the core protrusion and the core of the optical wiring at the same time is performed by arranging the first member having a shape corresponding to the shape, and the core protrusion is formed in the through hole forming portion provided in the mold. The second member having a shape corresponding to the desired shape is preferably provided.

  In the method for manufacturing a photoelectric wiring board according to the present invention, the clad protrusion and the core protrusion can be changed by adjusting the heights of the through hole forming portion, the first member, and the second member. It is preferable that

  According to the method for manufacturing a photoelectric wiring substrate of the present invention, in forming an optical waveguide that penetrates the substrate, the cladding filled in the through hole is processed by laser irradiation, and further, without passing through a complicated process of filling the core, Since the cladding protrusion and the first cladding of the optical wiring, the core protrusion and the core of the optical wiring, and the second cladding of the optical wiring are sequentially formed in the through hole formed in the substrate, the manufacturing process can be simplified. To obtain a good optical waveguide that does not require extra steps such as removing wrinkles generated during processing by laser irradiation, has a good interface between the core and the clad, and does not generate a boundary in the optical waveguide during manufacturing Can do.

  Further, according to the method for manufacturing a photoelectric wiring substrate of the present invention, since a lens can be formed on the end face of the core protrusion at the same time as the formation of the core of the optical wiring, there is no interface between the lens and the core, and extra light It is possible to obtain a photoelectric wiring board that does not cause propagation loss.

  Furthermore, in the method for manufacturing a photoelectric wiring board according to the present invention, a structure in which a clad protrusion and a first cladding of an optical wiring, a core protrusion and a core of an optical wiring, and a second cladding of an optical wiring are sequentially formed in a through-hole formed in the substrate. Therefore, the height of the clad protrusion and the core protrusion can be adjusted by appropriately adjusting the dimensions of the members used for the formation. For this reason, the photoelectric wiring board which can optimize optical coupling efficiency can be obtained by adjusting the space | interval with the clad protrusion part and core protrusion part which are optically coupled with an optical element.

  1-3 is a figure which shows each process of a preferable example of the manufacturing method of the photoelectric wiring board of this invention in steps. In the present invention, a step of forming electrical wiring on the surface of the substrate 1 (hereinafter referred to as “first step”), a part of the substrate 1 is removed so as to have a desired shape and size, and the through hole 8 is formed. And a step of forming the clad protrusion 9a and the first clad 4 of the optical wiring at the same time (hereinafter referred to as a “third step”). The step of forming the core protrusion 9b and the core 3 of the optical wiring at the same time, and further forming the optical path changing means in the core 3 (hereinafter referred to as “fourth step”), and the second cladding 5 of the optical wiring A process for forming a semiconductor substrate (hereinafter referred to as “fifth process”). Hereinafter, with reference to FIGS. 1-3, each process of the manufacturing method of the photoelectric wiring board of this invention is explained in full detail.

  First, in the first step, electric wiring is formed on the surface of the substrate 1. The substrate 1 is not particularly limited as long as it is a substrate that has been widely used in the art, but it is preferable to use a substrate formed of a resin having flexibility (flexibility). This is because by using the substrate 1 having flexibility, it can be freely attached even in a place having a concavo-convex structure, and the degree of freedom in wiring design using the photoelectric wiring substrate is increased. A resin that is made into a film with polyester, epoxy, polyimide, or the like and has flexibility can be considered as the substrate 1, but the processing temperature in the process of forming the optical waveguide to be the next optical wiring is particularly high (300 to 300- When the temperature is 400 ° C., it is preferable to select a resin having heat resistance, and it is preferable to use, as the substrate 1, a polyimide film having a small thermal shrinkage and excellent heat resistance. The thickness of the substrate 1 is not particularly limited, but is preferably 100 μm or less because a through hole can be easily formed.

  The electrical wiring is formed on the surface of the substrate 1 by forming a metal film on the substrate 1 by any method. As a method for forming the metal film, there are a method by vapor deposition and a method of bonding a metal foil. For example, in the case of a metal foil, the metal foil is bonded to the substrate 1, a resist is applied thereon, and then exposed. After forming a pattern of a portion to be removed by peeling off the resist, electric wiring is formed by wet etching the metal foil. In addition, when the above polyimide is used as the substrate, electrical wiring that does not peel from the substrate when the shape of the substrate is changed can be obtained by using copper having a linear expansion coefficient close to that of polyimide as the metal foil. In addition, the board | substrate 1 is provided with a 1st process and a 2nd process with the form normally supplied with a roll. The substrate 1 drawn from the roll is wet-treated with a metal film on one surface of the resin to form an electrical wiring including the electrode 10 (first step), and then subjected to the second step.

  In the subsequent second step, a part of the substrate is removed and a through hole is formed so as to have a desired shape and size. Here, the “desired shape and size” refers to a shape and size appropriately selected according to the photoelectric wiring substrate to be manufactured, and is not particularly limited. In the second step, specifically, the substrate 1 having the electric wiring formed on the surface thereof is, as shown in FIG. 1A, a mold (pedestal) 11 provided with a ring-shaped through-hole forming portion 12. And a punched substrate 13 provided with a hole 13a having a diameter R1 to be fitted to the through hole forming portion 12, and punching the substrate 1 to obtain a desired shape and size. A part of the substrate is removed so that the through hole 8 is formed. In the second step, press working is performed such that the base 11 is disposed on the side of the substrate 1 on which the electrical wiring including the electrode 10 is formed in the first step. As the pedestal 11, the substrate 1 provided through the first step in the state of being supplied by the roll as described above can be processed into a desired shape and size, and can be placed at a desired position on the substrate 1. What was designed beforehand so that the through-hole 8 is formed is used. In addition, as the base 11, what is generally used as a material of a metal mold | die in this field | area, for example, formed with SKD, SKH, SUS, a cemented carbide, etc. can be used suitably. Further, as shown in FIG. 1A, the through hole forming portion 12 of the base 11 has a diameter R <b> 1 of the hole 13 a of the punched substrate 13 (a through hole formed later on the substrate 1). It is preferable to use one having a diameter R2 smaller than the diameter of the hole 8 and having a diameter R3 smaller than the diameter R2 on the side away from the substrate. Thereby, the clad protrusion 9a and the core protrusion 9b described later can be easily formed.

  FIG. 1 (b) shows a state after press working with the mold. As shown in FIG. 1B, a ring-shaped through-hole forming portion provided in the pedestal 11 to form the through-hole 8 by pressing the substrate 1 between the pedestal 11 and the punched substrate 13. 12 and the hole 13a provided in the punched-out substrate 13 to be fitted, the substrate portion 15 where the through hole 8 having the diameter R1 is to be formed is removed. In the manufacturing method of the photoelectric wiring board of the present invention, in the second step, the through hole 8 is formed by punching by the ring-shaped through hole forming portion 12 provided in the base 11 as described above. In a later step, it is preferable to use the pedestal 11 as a holder for the substrate 1. As described above, in the second step, the substrate 1 is placed so that the side on which the electric wiring is formed contacts the pedestal 11 and is pressed, but the subsequent step is performed while the substrate 1 is held on the pedestal 11 as it is. Thus, the optical wiring can be easily formed on the side of the substrate 1 where the electrical wiring is not formed without preparing a separate holder, and the through hole forming portion 12 provided in the base 11 is provided. By utilizing the optical wiring (first clad 4, core 3, and second clad 5 described later), protrusions (cladding protrusions 9 a and core protrusions 9 b described later) can be formed simultaneously.

  In the subsequent third step, as shown in FIG. 2A, the clad protrusion 9a and the first clad 4 of the optical wiring are formed simultaneously. Specifically, in the state in which the first member 14a that fits the portion of the substrate 1 held on the pedestal 11 to the portion having the diameter R3 of the through hole forming portion 12 is disposed on the pedestal 11 of the substrate 1. A resin that is a material for forming the first cladding is applied to the non-contact side. Here, as the first member 14a, the length in the longitudinal direction is such that the tip protrudes beyond the tip of the through-hole forming portion 12 in a state of being fitted to the through-hole forming portion 12. Use.

  The resin that forms the first cladding is applied by, for example, a screen printing method so as to cover the through-hole forming portion 12. At this time, as described above, the portion having the diameter R3 in the through-hole forming portion 12 is provided with the first member 14a so as to be fitted to the portion. The resin forming the first cladding does not enter the projection 9b). And resin penetrates into the part which has diameter R2 larger than the part which has the said diameter R3 among the through-hole formation parts 12. FIG. After the resin is applied, the first clad 4 and the clad protrusion 9a are simultaneously formed by curing the resin by heat treatment. That is, the first clad 4 is formed by curing the resin applied to the surface of the substrate 1, and the clad protrusion 9a is formed by curing the resin that has entered the portion having the diameter R2 of the through hole forming portion 12. Is formed. The first member 14a used in the third step is not particularly limited, but is formed of, for example, SKD, SKH, SUS, or carbide, which is generally used as a mold material in this field. Can be used as appropriate.

  In the subsequent fourth step, as shown in FIG. 2B, the core projection 9b and the core 3 of the optical wiring are formed simultaneously, and further, the optical path changing means is formed in the core 3. Specifically, first, after the first member 14a used in the third step is extracted from the through hole forming portion 12, the second member 14 is fitted to the portion having the diameter R3 of the through hole forming portion 12. In the state where the member 14b is arranged, after forming the first clad 4 and the clad protrusion 9a, a resin as a core forming material is applied. Here, as the second member, one having a length in the longitudinal direction smaller than that of the first member 14a and preferably having the same length as the portion having the diameter R3 of the through hole forming portion 12 is used.

  The resin as the core forming material is applied by, for example, a screen printing method after the first clad 4 and the clad protrusion 9a are formed. At this time, as described above, the portion having the diameter R3 in the through-hole forming portion 12 is provided with the second member 14b so as to be fitted to the portion. The resin that forms does not enter. In the through-hole forming portion 12, the region having the diameter R2 larger than the portion having the diameter R3 in which the clad protrusion 9a is not formed (the first member 14a is disposed in the third step). In this case, the resin enters a region where the second member 14b is not disposed in the fourth step. After the resin is applied, the core 3 and the core protrusion 9b are formed simultaneously by curing the resin by heat treatment. In other words, the core 3 is formed by curing the resin applied on the first cladding 4, and enters the region of the through-hole forming portion 12 having the diameter R 2 where the cladding protrusion 9 a is not formed. The core protrusion 9b is formed by curing the resin. In addition, about the core 3 which propagates light, you may make it pattern in a desired shape after hardening of resin. Although it does not restrict | limit especially as the 2nd member 14b used in a 4th process, Like the 1st member 14a mentioned above, generally used as a material of a metal mold | die in this field, for example, SKD, Those formed of SKH, SUS, carbide or the like can be used as appropriate.

  In the fourth step, after the core protrusion 9b and the core 3 are formed, a photoelectric conversion means is further formed. Here, the “optical path conversion means” refers to means that can convert the optical path of light incident on the core, such as a lens or a mirror. In the example shown in FIG. 2B, in order to form the lens 7 on the end surface of the core projection 9b, the second member 14b is shaped to have a recess 14b1 having a predetermined radius of curvature. Show. By using the second member 14b having such a recess 14b1, when the above-described resin material forming the core is applied, the resin also enters the recess 14b1, and this is cured. The hemispherical lens 7 protruding so as to have a predetermined curvature can be formed on the end surface of the core protrusion 9b. Note that the shape of the second member 14b used in the fourth step is not limited to the shape having the recess 14b1 as shown in FIG. 2B, but has an appropriate shape as necessary. Can be selected and used.

  Further, a mirror 6 for converting the optical path may be formed on the core 3 (FIG. 2B). As a method for forming the mirror, a method using a cut surface by a dicer may be used. Further, a metal reflecting surface or the like may be formed on the mirror surface 6 as necessary.

  In the fifth step, the second cladding 5 of the optical wiring is formed as shown in FIG. Specifically, a resin as a second clad forming material is applied on the core 3 formed in the fourth step. Application of the resin that forms the second cladding is performed by, for example, a screen printing method, and after application, the resin is cured by heat treatment to form the second cladding 5.

  After each of these steps, the photoelectric wiring substrate as shown in FIG. 3B is manufactured by extracting the second member 14b from the through-hole forming portion 12 and separating the substrate 1 from the pedestal 11. Can do. 3B is shown upside down with respect to the paper surface of FIG. 3A. In the manufacturing method of the present invention, the clad protrusion 9a and the core protrusion 9b (these are collectively referred to as “protrusion 9”), the first member 14a, the second member 14b, and the through hole formation. In order that the part 12 may be easily peeled off, the surface of the mold that has been previously coated with a coating treatment or a release agent may be used.

  According to the method for manufacturing a photoelectric wiring substrate of the present invention described above, in forming an optical waveguide that penetrates the substrate, the cladding filled in the through hole is processed by laser irradiation and further subjected to a complicated process of filling the core. Instead, the clad projection 9a, the first clad 4 of the optical wiring, the core projection 9b, the core 3 of the optical wiring, and the second clad 5 of the optical wiring are formed sequentially in the through hole 8 formed in the substrate 1, so that the manufacturing process In addition, an extra process such as removal of wrinkles generated during processing by laser irradiation is not required, the interface between the core 3 and the clads 4 and 5 is good, and the optical waveguide is manufactured during manufacturing. A good optical waveguide can be obtained in which no boundary portion is generated.

  Further, according to the method for manufacturing a photoelectric wiring board of the present invention, since the lens 7 can be formed on the end surface of the core projection 9b simultaneously with the formation of the core 3 of the optical wiring, there is no interface between the lens 7 and the core 3. Thus, it is possible to obtain a photoelectric wiring substrate that does not generate extra light propagation loss.

  In the method for manufacturing a photoelectric wiring substrate according to the present invention, the first clad 4 and the second clad 5 need to be formed of a resin having a refractive index smaller than that of the core. For this reason, the resin used as the first clad forming material used in the third step and the resin used as the second clad forming material used in the fifth step are the core forming material used in the fourth step. It is necessary to use a resin having a smaller refractive index than the resin to be formed. For example, a material in which an appropriate additive is added to a resin as a core forming material, or a material whose refractive index is changed by changing the molecular weight of the resin as a core forming material is referred to as a first cladding forming material. Can be used as a resin for forming the second clad.

  In addition, the first clad, the core, and the second clad are formed as an optical waveguide by sequentially applying and curing the resin as the forming material. However, the first clad, the core, and the second clad are peeled off at the boundary due to a large difference in linear expansion coefficient. In order not to cause problems such as cracks, it is desirable to use the same material and a resin whose refractive index is controlled as described above as the forming material, or a resin having a similar linear expansion coefficient. .

  Furthermore, in the present invention, a refractive index difference can be formed according to the characteristics of the optical waveguide as the resin that forms the first cladding, the resin that forms the second cladding, and the resin that forms the core. It is preferable to use different resins. For example, when heat resistance is required for the optical waveguide, a heat resistant resin (for example, polyimide resin) may be used, and when processability is required for forming the optical waveguide, By using a photosensitive resin (for example, polysilane resin) that reduces the refractive index of the irradiated region when irradiated with light, an optical waveguide can be easily formed using the irradiated region as a cladding. it can.

  FIG. 4 is a diagram schematically showing a preferred example of the photoelectric wiring board obtained by the production method of the present invention. As shown in FIG. 4, the photoelectric wiring substrate obtained by the present invention includes a first cladding 4, a core 3, and a second cladding 5 (hereinafter referred to as a first cladding 4, a core 3, and a second cladding 5) on the substrate 1. And a basic structure in which the optical wirings 2 "are generically stacked. In the optical wiring 2 in such a photoelectric wiring substrate, light emitted from a light emitting element (not shown) propagates through the core 3 sandwiched between the first clad 4 and the second clad 5 forming the optical waveguide and receives light. It is configured to reach an element (not shown).

  The substrate 1 in the photoelectric wiring substrate includes an electrode 10 for mounting a light emitting element (not shown) and a light receiving element (not shown) (hereinafter, these elements are collectively referred to as “optical elements”). Electrical wiring is formed. Further, an optical waveguide serving as the optical wiring 2 is formed on the side of the substrate 1 opposite to the side on which the electrodes 10 and the like are formed. In general, when an optical wiring 2 is formed on one side of a photoelectric wiring board, it is difficult to arrange an optical element on the side where the optical wiring 2 is formed. Therefore, in the photoelectric wiring substrate obtained by the manufacturing method of the present invention, the through hole 8 is formed in the substrate 1 as shown in FIG. 4, the optical wiring 2 is sequentially laminated on one side of the substrate 1, and the through hole 8 is formed. By forming the protrusions 9 (cladding protrusions 9a and core protrusions 9b) so as to protrude into the inside of the optical fiber 2, the light incident on the optical wiring 2 on the side opposite to the optical wiring 2 can be taken out. As a result, the optical element can be mounted on the side opposite to the optical wiring 2 (that is, the side on which 10 electric wirings including the electrodes are formed).

  The optical wiring 2 in the photoelectric wiring substrate constitutes an optical waveguide composed of the first cladding 4 and the second cladding 5 and the core 3 surrounded by them. As described above, the first cladding 4 and the second cladding 5 are formed of the same resin material, and the core 3 is formed of a resin material having a higher refractive index than the material forming the claddings 4 and 5. Therefore, the light incident on the optical waveguide propagates through the core 3 while being totally reflected at the interface between the first cladding 4 and the second cladding 5 and the core 3. The refractive index of the resin forming the core 3 and the clad 4 (or 5) may be appropriately adjusted according to the light propagation angle. The larger the refractive index difference between the core 3 and the clads 4 and 5, the larger the light propagation angle.

  In the photoelectric wiring substrate of the example shown in FIG. 4, a mirror 6 that converts an optical path of light is formed on the core 3 as an optical path converting means, and the optical axis is the same as that of the optical wiring 2 via the mirror 6. A core protrusion 9b surrounded by the protrusion 9a is formed perpendicular to the optical axis direction of the optical wiring 2 to constitute an optical waveguide. A plurality of structures having such protrusions 9 are formed on the photoelectric wiring substrate, and mirrors 6 opposite to each other are formed on the core 3 that connects the adjacent protrusions 9 as shown in FIG. Then, the light incident on the core projection 9b is vertically converted by the mirror 6 to propagate the light in the core 3 of the optical wiring 2, and further perpendicularly by the mirror 6 in the portion where the adjacent projection 9 is disposed. It is possible to change the optical path and extract light at the adjacent core protrusion 9b (in FIG. 4, the optical path is indicated by a broken line). With such a configuration, light incident on the optical wiring 2 from the side where the electrical wiring including the electrode 10 of the substrate is formed is guided to the side where the electrical wiring including the electrode 10 of the substrate is formed. be able to.

  Furthermore, in the photoelectric wiring board obtained by the present invention, a hemispherical lens 7 having a specific radius of curvature is provided on the end face of the core protrusion 9b so as to protrude from the end face of the core protrusion 9b (see FIG. FIG. 4). By forming such a lens 7, the efficiency of optical coupling between the optical element and the optical waveguide can be increased.

  Here, the photoelectric wiring substrate obtained by the manufacturing method of the present invention is such that a space (groove) is provided between the clad protrusion 9 a and the wall surface of the through hole 8 in the through hole 8 provided in the substrate 1. The point has its great characteristics. Such a structure is inevitably obtained by being obtained by the above-described method for manufacturing a photoelectric wiring substrate, but it ensures the reliability of the optical wiring 2, particularly the protrusion 9, and further the optical element is connected to the photoelectric wiring. It plays an important role in optimizing the optical coupling between the optical element and the optical waveguide when mounted on the substrate.

  FIG. 5 is a diagram schematically showing a state in which the optical element 16 is mounted on the photoelectric wiring board obtained in the present invention. In general, the optical element is implemented on the substrate 1 using solder, and the temperature of the solder at the time of mounting using the solder is high (about 200 to 300 ° C.). However, since the photoelectric wiring board obtained by the present invention has a structure in which a space (groove) is provided between the clad protrusion 9b and the wall surface of the through-hole 8 as described above, Even when heat is conducted to the substrate 1, heat is not conducted to the protrusions 9 in the vicinity thereof. Therefore, when the optical element is mounted, heat is conducted to the protruding portion, so that the optical waveguide formed as the protruding portion is not deformed due to high temperature, and in order to prevent this deformation, It is not necessary to use a heat-resistant resin (for example, polyimide) as the resin used for forming the optical wiring 2. As described above, the photoelectric wiring board obtained in the present invention can suppress the influence of the heat of the protrusion 9 when mounting the optical element, and further has a degree of freedom in selecting a resin that can be used as an optical waveguide. There is an advantage of being large.

  In the example shown in FIG. 5, the optical element 16 is mounted on the electrode 10 formed on the substrate 1 by solder 18. As described above, the optical element 16 includes a light emitting element and a light receiving element. As the light emitting element, for example, an edge emitting laser diode or a surface emitting laser diode (VCSEL) can be used. As the light emitting element, it is preferable to use a light emitting element that oscillates light in a wavelength range that is different from the wavelength range in which the resin that forms the optical waveguide absorbs light or has little absorption. By using such a light emitting element as a light source, it becomes possible to suppress the propagation loss of light in the optical waveguide, and the degree of freedom in designing the optical wiring is further increased. Further, as the light receiving element, a photodiode (PD) capable of receiving a wavelength range in which the light emitting element to be used oscillates can be used. The size of the light receiving surface of the PD may be determined according to the transmission capacity. In the example shown in FIG. 5, components other than the optical element 16 are omitted, but similarly to the optical element 16, they are appropriately mounted in a form normally performed in this field. I do n’t mind.

  FIG. 6 is a diagram for explaining the positional relationship between the protrusion 9 and the optical element 16 in the photoelectric wiring substrate obtained by the present invention. As described above, in the method for manufacturing a photoelectric wiring board according to the present invention, the clad protrusion 9a, the first clad 4, the core protrusion 9b, the core 3, and the second clad 5 are sequentially formed in the through hole 8 formed in the substrate 1. It is characterized by forming. Therefore, in the manufacturing method of the present invention, it is possible to appropriately adjust the dimensions of the members (the through-hole forming portion 12, the first member 14a, and the second member 14b described above) used for forming these members. The height of the clad projection part 9a and the core projection part 9b can be adjusted by adjusting the dimensions appropriately. As a result, in the method of manufacturing a photoelectric wiring board according to the present invention, the photoelectric wiring board can optimize the optical coupling efficiency by adjusting the distance between the clad protrusion 9a and the core protrusion 9b that are optically coupled to the optical element 16. It also has a special effect that can be obtained. Hereinafter, a method for optimizing the optical coupling efficiency by adjusting the positional relationship between the protrusion 9 and the optical element 16 will be described in detail with reference to FIG. FIGS. 6A and 6B show a configuration in which a lens is not formed on the end surface of the core protrusion 9b for the sake of simplicity. In the case where no is formed, it is sufficient to adjust the positional relationship by the thickness of the lens, which can be considered almost the same.

  As shown in FIG. 6, for example, in the optical element 16, the diameter of the optical element surface is a, the full angle of the emitted light of the light is θ, the diameter of the core protrusion 9b is W, and the optical element surface and the core protrusion 9b The distance to the end face is h, and the distance between the substrate 1 and the optical element 16 is H. Here, the distance H is a parameter that depends on the thickness of the electrode 10 and the thickness of the solder 18. In such a configuration, in order for all the light beams of the optical element 16 to be coupled to the optical waveguide, the spread of the light beam at the position of the distance h, that is, a + 2 × h × tan (θ / 2) is derived from the core diameter W of the optical waveguide. It is necessary to have a small relationship (a + 2 × h × tan (θ / 2) <W). Here, the propagation angle between the core 3 of the optical waveguide and the clads 4 and 5 (the core protrusion b and the clad protrusion 9a) is not considered. At this time, the position of the end face of the protrusion 9 is projected from the surface of the substrate 1 depending on the relationship between the distance h between the optical element 16 and the protrusion 9 and the distance H to the substrate, or from the surface of the substrate 1. It is necessary to adjust whether the position is depressed.

  For example, when a VCSEL is used as the light emitting element, if H = 20 μm and W = 20 μm with respect to the VCSEL characteristics (a = 10 μm, θ = 50 °), h = 10.7 μm is obtained from the calculation, and H> h Therefore, the protruding portion 9 needs to protrude from the surface of the substrate 1. That is, if the end surface of the protrusion 9 is flush with the surface of the substrate or is recessed from the surface of the substrate 1, the VCSEL beam is not sufficiently optically coupled to the optical waveguide and the light coupling loss increases. .

  On the other hand, if the light receiving surface has a sufficiently large light receiving surface, a lens is not required, and if the light receiving surface and the protrusion are made closer, sufficient optical coupling efficiency can be achieved even if the mounting accuracy of the light receiving device is poor. Can be obtained.

  FIG. 6B schematically shows an example of the positional relationship between the optical element 16 and the protrusion 9 obtained by the above-described calculation. As can be seen from comparison with the photoelectric wiring substrate of the example shown in FIG. 4, the photoelectric wiring substrate of the example shown in FIG. 6B is formed so that the protruding portion 9 protrudes from the surface of the substrate 1. The Thereby, even in the above-described case where, for example, a VCSEL is used as the optical element 16, sufficient optical coupling efficiency can be obtained. Further, when the numerical aperture (NA) of the optical waveguide is smaller than the NA = 0.42 of the emission light of the VCSEL, a lens 7 is provided on the end face of the protrusion 9 so that the NA of the emission light is larger than the NA of the optical waveguide. The efficiency of optical coupling can be optimized by adjusting the shape of the lens 7 and the distance between the projection 9 and the light emitting surface so as to decrease.

  As described above, since the positional relationship between the optical element 16 and the protruding portion 9 greatly depends on the optical element and the optical waveguide to be used, the photoelectric wiring board may adjust the position of the protruding portion 9 appropriately according to circumstances. It is desirable that the configuration be able to. As described above, according to the method for manufacturing a photoelectric wiring substrate of the present invention, the dimensions of the through-hole forming portion 12 provided in the pedestal 11 that holds the substrate 1, the first member 14a, and the second member 14b. By adjusting as necessary, it is possible to easily manufacture a photoelectric wiring board in which the positions of the protrusions in the photoelectric wiring board are appropriately adjusted as desired.

  Hereinafter, a method for manufacturing a photoelectric wiring substrate (another preferable example of the manufacturing method of the present invention) in the case where the end face of the protruding portion 9 is arranged to protrude from the surface of the substrate 1 will be described with reference to FIGS. To explain. According to the method for manufacturing a photoelectric wiring board of the present invention, the photoelectric wiring board in the case where the end surface of the protruding portion 9 is arranged to protrude from the surface of the substrate 1 can also be preferably manufactured. In addition, description about the other preferable example of the manufacturing method of this invention is abbreviate | omitted description about the part which overlaps with the preferable example of the manufacturing method of this invention mentioned above with reference to FIGS. 1-3, and the same part. The differences from the above example will be described in detail. 7 (a), (b), FIG. 8 (a), (b), FIG. 9 (a), (b) are the same as FIG. 1 (a), (b), FIG. 2 (a), ( b) and a manufacturing process corresponding to FIGS. 3A and 3B, respectively.

  First, in the same manner as the above-described example, electric wiring including the electrode 10 is formed on the surface of the substrate 1 in the first step. In another example of the manufacturing method of the present invention, the pedestal 11 on which the through hole forming portion 12 used in the subsequent second step is formed is a boundary surface (AA) between the portion having the diameter R2 and the portion having the diameter R3. ') Is set at a position lower than the surface (BB') on the side of the pedestal 11 that contacts the substrate 1. More specifically, the positional relationship (Hh) between the end face of the desired protrusion 9 and the substrate 1 is estimated in advance, and based on the result, the portion having the diameter R2 and the diameter of the through-hole forming portion 12 The height of the boundary surface (AA ′) with the portion having R3 is set. Such a height change can be easily performed by setting the thickness of the pedestal 11 to be thicker than that used in FIG. 1A, and the through hole 8 is formed in the substrate 1. Above is not a problem at all. That is, even when such a pedestal 11 is used, similarly to the case shown in FIG. 1A, a pedestal 11 and a hole 13a having a diameter R1 that fits the through hole forming portion 12 are provided. The substrate 1 is sandwiched between the punched substrate 13 and pressed, so that the substrate 1 is punched out, and a part of the substrate is removed to form a desired shape and size, and the through-hole 8 is formed. it can. (FIGS. 7A and 7B).

  Subsequently, in the third step, the through-hole forming portion 12 is covered with a resin material forming the first cladding in a state where the first member 14a is fitted to the portion having the diameter R3 of the through-hole forming portion 12. Then, the clad protrusion 9a and the first clad 4 are formed simultaneously by applying and drying (FIG. 8A). Then, in the fourth step, after the first member 14a is extracted from the through hole forming portion 12, the core is formed with the second member 14b fitted to the portion having the diameter R3 of the through hole forming portion 12. The resin material to be applied is applied on the first clad 4 and the clad protrusion 9a and then dried to simultaneously form the core protrusion 9b and the core 3. The lengths in the longitudinal direction of the first member 14a and the second member 14b may be appropriately changed according to the thicknesses of the substrate 1 and the pedestal 11, respectively.

  After the core protrusion 9b and the core 3 are formed, the optical path changing means is formed. In FIG. 8B, corresponding to the structure shown in FIGS. 6A and 6B, only the mirror 6 is formed as the optical path changing means, and the end surface of the core protrusion 9b is formed without forming the lens 7. In the same manner as in the example shown in FIGS. 1 to 3, a concave portion having a specific radius of curvature is formed in the second member 14b, and a lens is formed on the end surface of the core protruding portion 9b. Of course, 7 may be formed.

  Thereafter, the second cladding 5 is formed in the fifth step (FIG. 9A), and the pedestal 11 and the second member 14b are removed, so that the end surface of the core protrusion 9b as shown in FIG. A photoelectric wiring board having a structure protruding from the surface of 1 can be manufactured (FIG. 9B).

It is a figure which shows each process of a preferable example of the manufacturing method of the photoelectric wiring board of this invention in steps. It is a figure which shows each process of a preferable example of the manufacturing method of the photoelectric wiring board of this invention in steps. It is a figure which shows each process of a preferable example of the manufacturing method of the photoelectric wiring board of this invention in steps. It is a figure which shows typically a preferable example of the photoelectric wiring board obtained with the manufacturing method of this invention. It is a figure which shows typically the state which mounted the optical element on the photoelectric wiring board obtained by this invention. It is a figure for demonstrating the positional relationship of the projection part 9 and the optical element 16 in the photoelectric wiring board obtained by this invention. It is a figure which shows each process of the preferable other example of the manufacturing method of the photoelectric wiring board of this invention in steps. It is a figure which shows each process of the preferable other example of the manufacturing method of the photoelectric wiring board of this invention in steps. It is a figure which shows each process of the preferable other example of the manufacturing method of the photoelectric wiring board of this invention in steps. It is the schematic which shows the manufacturing method of the conventional photoelectric wiring board. It is the schematic which shows the conventional photoelectric wiring board.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Board | substrate, 2 Optical wiring, 3 Core, 4 1st clad, 5 2nd clad, 6 Mirror, 7 Lens, 8 Through-hole, 9 Protrusion part, 9a Clad protrusion part, 9b Core protrusion part, 10 Electrode, 11 base, 12 through-hole forming portion, 13 blank substrate, 14a first member, 14b second member, 16 optical element, 18 solder.

Claims (4)

Forming electrical wiring on the substrate surface;
Removing a part of the substrate so as to have a desired shape and size and forming a through hole; and
Forming the clad protrusion and the first clad of the optical wiring simultaneously;
Forming the core protrusion and the core of the optical wiring simultaneously, and further forming the optical path changing means in the core;
Forming a second clad of the optical wiring.   In the step of removing a part of the substrate and forming a through hole so as to have the desired shape and size, the through hole is formed by punching by a ring-shaped through hole forming portion provided in a mold, The method for manufacturing a photoelectric wiring substrate according to claim 1, wherein the mold is used as a holder for the substrate in a step after the step. In the step of simultaneously forming the clad protrusion and the first clad of the optical wiring, a first member having a shape corresponding to a desired shape of the clad protrusion is disposed in the through hole forming portion provided in the mold. Done,
In the step of simultaneously forming the core protrusion and the core of the optical wiring, a second member having a shape corresponding to a desired shape of the core protrusion is arranged in the through hole forming portion provided in the mold. The method for producing a photoelectric wiring substrate according to claim 2, wherein the method is performed.   The clad protrusion and the core protrusion can be changed by adjusting the heights of the through hole forming portion, the first member, and the second member. The manufacturing method of the photoelectric wiring board in any one.

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