JP4304764B2 - Optical / electrical wiring board, manufacturing method, and mounting board - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical / electrical wiring board in which optical wiring and electrical wiring are mixed, a method for manufacturing the same, and a mounting board in which optical components and electrical components are mounted on the substrate.
[0002]
[Prior art]
In order to make a computer that can perform arithmetic processing faster, the clock frequency of the CPU tends to increase more and more, and about 1 GHz now appears. As a result, there are parts where high-frequency signals flow in the electrical wiring of copper on the printed circuit board in the computer, so malfunctions may occur due to the generation of noise, and electromagnetic waves may be generated, affecting the surroundings. It will also give.
[0003]
In order to solve such a problem, a part of the copper electrical wiring on the printed circuit board is replaced with an optical fiber or optical waveguide optical wiring, and an optical signal is used instead of the electrical signal. This is because the generation of noise and electromagnetic waves can be suppressed in the case of optical signals.
[0004]
From the viewpoint of high-density mounting or downsizing, it is desirable to make an optical / electrical wiring board in which electrical wiring and optical wiring are stacked on the same substrate, but conventional optical / electrical wiring boards are laser light emitting devices. When optical components such as light receiving elements are mounted, it is difficult to optically match the optical axis of the optical component and the optical axis of the optical wiring. In general, they cannot be matched unless relying on skilled workers. Therefore, compared with an electrical component that can be automatically soldered in a reflow furnace or the like, mounting an optical component on an optical / electrical wiring board has a drawback of becoming very expensive.
[0005]
[Problems to be solved by the invention]
The present invention has been made in view of the drawbacks of the related art, and provides an optical / electrical wiring board that can be mounted at a high density or miniaturized and that can mount optical components in the same manner as electrical components. This is the issue.
[0006]
[Means for Solving the Problems]
In order to achieve the above object in the present invention, first, in the invention of claim 1, an optical wiring layer having an optical fiber for propagating an optical signal as an optical wiring on the electric wiring of a substrate having electric wiring. An electrical wiring board, a mirror provided in a part of the optical fiber, an optical wiring layer in which the optical fiber is installed on the first resin layer, and a second resin layer is installed thereon; The first resin layer is used to fix the optical fiber, the first resin layer is used to mount the optical component, and the optical component is mounted on the optical component. A pad for an optical component made of metal installed on the upper surface of the optical wiring layer, a pad for an electric component provided on the upper surface of the optical wiring layer for soldering the electric component, and an optical component Electrical wiring between board and board for electrical or electrical components A via hole for electrically connecting, in which the optical and electrical wiring board, characterized by comprising an electric wiring provided on the light wiring layer.
[0009]
The invention of claim 2 is a method of manufacturing an optical / electrical wiring board including an optical wiring layer having an optical fiber for propagating an optical signal as an optical wiring on the electric wiring of the substrate having electric wiring, (I) A first resin layer is applied onto the support, and the first resin layer is etched using the metal film as a mask. A protrusion made of one resin layer for mounting an optical component, and a pad using the mask as a metal pad for soldering the optical component on the protrusion for mounting the optical component; An optical fiber is installed in alignment with the protrusion for fixing the optical fiber, and the optical fiber and the pad are embedded using a second resin layer from above, and the second surface is exposed so that the surface of the pad is exposed. By removing the resin layer of An optical wiring layer and a step of forming a pad on the upper surface of the optical wiring layer; (ii) a step of peeling the optical wiring layer from the support; (iii) a surface of the optical wiring layer on which the pad is formed; Bonding the second support, (iv) providing a mirror by forming a 45 ° inclined surface at a desired position of the optical fiber in the optical wiring layer, and (v) having the electrical wiring A step of bonding the substrate and the optical wiring layer; (vi) a step of forming a via hole for electrically connecting the electric wiring on the substrate and the pad; and the above steps (i) to (vi). This is a method for manufacturing an optical / electrical wiring board.
[0010]
According to a third aspect of the present invention, there is provided a mounting board in which an optical component and / or an electric component is mounted on the optical / electrical wiring board according to the first aspect.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
1. Optical / Electric Wiring Substrate In the optical / electrical wiring substrate of the present invention, a top view of a portion where an optical component is mounted is shown in FIG. 2 is a cross-sectional view taken along the optical fiber 1, and FIG.
[0012]
The optical / electrical wiring board of the present invention has a structure in which an optical wiring layer 15 is laminated on a substrate 14 provided with electric wirings 16, 17, 18, 19 via an adhesive layer 13. The substrate 14 may be a single-layer insulating substrate or a multilayer wiring substrate in which electrical wiring and insulating layers are alternately stacked. The constituent material may be an insulating substrate in which a glass cloth is impregnated with a resin, a polyimide film, a ceramic substrate, or a multilayer wiring substrate based on them.
[0013]
In the optical wiring layer 15, the optical fiber 1 is embedded between the first resin layer 3 and the second resin layer 4 as an optical wiring for propagating an optical signal. The optical fiber 1 includes a core layer 1b through which an optical signal propagates and a cladding layer 1a that confines the optical signal in the core layer. The optical fiber 1 is fixed between the protrusions 3a made of the first resin layer 3, and the position of the core layer in the optical wiring layer is arbitrarily determined.
[0014]
The optical fiber is formed with a mirror 2 that reflects the laser light, which is an optical signal, and changes the propagation direction to 90 °. This mirror inserts an optical signal emitted from the laser light emitting element mounted on the optical / electrical wiring board of the present invention in the vertical direction toward the substrate into an optical fiber arranged in parallel with the substrate surface. The optical signal that has propagated through the optical fiber plays a role to change the propagation direction of the optical signal vertically toward the light receiving element installed on the optical / electrical wiring board of the present invention. A surface forming 45 ° is formed. The mirror 2 may be provided with a reflective layer made of a metal vapor deposition film. Further, a material having a refractive index lower than that of the core layer 1b may be provided on the mirror surface. This mirror can be formed at an arbitrary position of the optical wiring layer using an alignment mark.
[0015]
Pads 5, 6, 7, and 8 for mounting optical components such as a laser light emitting element and a light receiving element are disposed on the periphery of the mirror 2. This pad is formed on the protrusion 3 b made of the first resin layer 3. Since the protrusion 3b made of the first resin layer under the pad and the protrusion 3a made of the first resin layer for fixing the optical fiber 1 can be simultaneously formed by a photolithography technique through one photomask, As a result, the position of the core layer of the optical fiber, the position of the mirror, and the position of the pad can be determined with high accuracy. In addition, since the optical component can be connected to the optical / electrical wiring board of the present invention through a reflow furnace, the self-alignment effect at the time of melting of the solder allows the light emitting surface of the laser light emitting element or the light receiving surface of the light receiving element to be connected. Position accuracy can also be improved.
[0016]
The optical component pads 6, 8 are connected to the electrical wirings 17, 19 through via lands 10, 12 and via holes 21, 20. Although not shown, the optical component pads 5 and 7 are similarly connected to the optical wirings 16 and 18.
[0017]
The resin forming the first resin layer preferably has a high glass transition temperature Tg, a high insulation resistance, and a low coefficient of thermal expansion. Examples of film formation methods include thermosetting and photocuring. It is done. For example, a polyimide resin or an epoxy resin is suitable.
[0018]
As the characteristics of the resin forming the second resin layer, the glass transition temperature Tg, the insulation resistance, and the coefficient of thermal expansion are good as in the first resin. In addition, the characteristics of the cladding layer of the optical fiber are good. It is necessary to select one that is equal to the refractive index. Therefore, the same material as the second resin may be used as the resin of the first resin layer.
[0019]
FIG. 4 is a cross-sectional view when the lead 34 of the laser light emitting element 32 such as a semiconductor laser is soldered on the pads 5, 6, 7, and 8. The laser beam 31 emitted from the laser emitting surface 33 of the laser emitting element 32 is reflected by the mirror 2 and propagates through the optical fiber 1.
[0020]
FIG. 5 is a cross-sectional view when the lead 44 of the light receiving element 42 such as a photodiode is soldered on the pads 5, 6, 7, and 8. The laser beam 41 propagating through the optical fiber 1 is reflected by the mirror 2 and enters the light receiving surface 43 of the light receiving element 42.
[0021]
As described above, the mutual positional relationship among the core layer 1b of the optical fiber 1, the pad 5, the pad 6, the pad 7, the pad 8, and the mirror 2 is extremely high as intended. Since they coincide with each other with high accuracy, when the lead of the optical component is placed on the pads 5, 6, 7, 8, the optical axis of the optical component and the optical axis of the core layer of the optical fiber 1 are optically aligned. Therefore, the optical component can be automatically soldered in a reflow furnace or the like.
[0022]
Pads for soldering electrical components may be provided on the optical wiring layer of the optical / electrical wiring board, or electrical wiring may be provided. The pad for the electric component may be electrically connected to the wiring on the substrate by a via hole in the same manner as the pad for the optical component.
[0023]
When the electrical wiring is provided on the optical wiring layer, the pad may be electrically connected only to the electrical wiring on the optical wiring layer and may not be electrically connected to the electrical wiring on the substrate. In this case, of course, there is no via hole for electrically connecting the pad and the electric wiring on the substrate.
[0024]
2. Manufacturing Method of Optical / Electrical Wiring Substrate The manufacturing method of the optical / electrical wiring substrate of the present invention is basically as follows. First, apart from a substrate having electrical wiring, an optical wiring layer is formed on a support. At this time, a projection for fixing the optical fiber and a pad for soldering the optical component are simultaneously formed by photolithography. Next, a mirror is provided on a part of the optical fiber and bonded to the substrate. Further, a via hole for electrically connecting the pad and the electric wiring on the substrate is formed.
[0025]
Hereinafter, one embodiment will be described in accordance with the flow of FIGS. 6A to 6N, focusing on the pads for optical components that are electrically connected to the electrical wiring on the substrate by via holes.
[0026]
As shown in FIG. 6A, a release layer 52 is formed on the first support 51. The first support 51 is excellent in heat resistance and fastness, and has a thermal expansion coefficient that is equal to or close to that of the first resin layer and the second resin layer. .
[0027]
As illustrated in FIG. 6B, the first resin layer 53 is formed on the release layer 52.
[0028]
A metal film is formed on the first resin layer 53, and the metal film is mounted with a projection pattern 54 for fixing an optical fiber and an optical component by photolithography as shown in FIG. 6C. The pad protrusion pattern 55 is processed.
[0029]
As shown in FIG. 6D, an optical fiber fixing protrusion 56 and an optical component mounting pad protrusion 57 are formed by dry etching using a metal film as a metal mask.
[0030]
As shown in FIG. 6E, the optical fiber 58 is fixed.
[0031]
As shown in FIG. 6F, the second resin layer 59 is formed.
[0032]
As shown in FIG. 6G, the second resin layer is removed by dry etching from the upper surface of the second resin layer 59 until the surfaces of the metal film patterns 54 and 55 are exposed.
[0033]
The optical wiring layer 60 is peeled off as shown in (h) of FIG. Before being immersed in the stripping solution, a protective film is formed on the metal film pattern forming surface as required (not shown).
[0034]
As shown in (i) of FIG. 6, the metal film pattern forming surface side is bonded to the second support 61. As the adhesive, an adhesive that can be easily peeled is used, or an adhesive whose adhesive strength is reduced by being cured with heat or ultraviolet rays.
[0035]
As shown in FIG. 6J, a groove is formed in the optical wiring layer by dicing or dry etching to form a mirror 62.
[0036]
As shown in FIG. 6K, the mirror 62 side of the optical wiring layer is bonded to the side of the substrate 63 having the electric wiring 64 with an adhesive. As a result, the optical wiring layer 60 is bonded to the substrate 63 with the adhesive layer 65 interposed therebetween.
[0037]
As shown in FIG. 6L, the second support 61 is peeled off from the optical wiring layer. When the second support 61 and the optical wiring layer 60 are bonded to each other, when an adhesive that is cured with heat or ultraviolet rays is used, the adhesive is cured with heat or ultraviolet rays and then peeled off.
[0038]
As shown in FIG. 6M, a hole 66 for forming a via hole is opened by a laser in the vicinity of the optical component mounting pad 55. In this case, the electrical wiring 64 serves as a stopper during laser processing.
[0039]
Further, the metal film pattern 54 formed on the optical fiber fixing protrusion is removed.
[0040]
A metal layer is formed in the via hole 68 and on the via hole land 67 connected to the pad 55 by the semi-additive method, and the optical / electrical wiring board of the present invention is obtained as shown in FIG. If necessary, pads for electrical components (not shown), via holes (not shown) for electrically connecting the electrical pads and electrical wiring (not shown) can be formed at the same time. .
[0041]
3. Manufacturing method of mounting substrate Optical components (laser, photodiode) and electrical components (CPU, memory) were mounted on an optical / electrical wiring substrate using solder.
[0042]
【The invention's effect】
The present invention has the following effects.
[0043]
First, since an optical wiring layer is provided on a substrate having electrical wiring, there is an effect that high-density mounting or miniaturization is possible.
[0044]
Second, since the mutual positional relationship between the core layer of the optical fiber, the pad for mounting the optical component, and the mirror coincides with the intended one with extremely high accuracy, the optical axis of the optical component and the optical axis of the optical fiber Can be optically matched with each other, so that the optical component and the electrical component can be automatically mounted simultaneously.
[0045]
Thirdly, since the electrical wiring is also provided on the optical wiring layer, there is an effect that interference between the electrical wirings can be suppressed.
[0046]
Fourth, separately from the substrate having the electrical wiring, the optical fiber is fixed to the optical wiring layer on the support and the optical wiring layer is bonded to the substrate, so that the optical fiber is directly attached on the electrical wiring on the substrate. Compared with the case of installation, the influence of the unevenness of the electrical wiring on the substrate can be reduced, and the propagation loss of the optical signal of the optical fiber can be reduced.
[0047]
[Brief description of the drawings]
FIG. 1 is a top view of a portion where an optical component is mounted on an optical / electrical wiring board according to the present invention.
FIG. 2 is a cross-sectional view across an optical fiber in a portion where an optical component is mounted in the optical / electrical wiring board of the present invention.
FIG. 3 is a cross-sectional view taken along an optical fiber in a portion where an optical component is mounted in the optical / electrical wiring board of the present invention.
FIG. 4 is a view for explaining propagation of laser light when a laser light emitting element is mounted on the optical / electrical wiring board of the present invention.
FIG. 5 is a view for explaining propagation of laser light when a light receiving element is mounted on the optical / electrical wiring board of the present invention.
FIG. 6 is a view for explaining a method for manufacturing an optical / electrical wiring board according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Optical fiber 1a Clad layer 1b Optical fiber cladding layer 1b Optical fiber core layer 2 Mirror 3 First resin layer 3a Optical fiber fixing protrusion 3b Optical component mounting pad protrusion 4 Second resin layer 5 Optical component mounting Pad 6 Optical component mounting pad 7 Optical component mounting pad 8 Optical component mounting pad 9 Land 10 Land 11 Land 12 Land 13 Adhesive layer 14 Substrate 15 Optical wiring layer 16 Electrical wiring 17 Electrical wiring 18 Electrical wiring 19 Electrical wiring 20 Via hole 21 Via hole 31 Laser light 32 Laser light emitting element 33 Laser light emitting surface 34 Lead 35 Solder 41 Laser light 42 Light receiving element 43 Light receiving surface 44 Lead 45 Solder 51 First support body 52 Release layer 53 First resin layer 54 Optical fiber fixing Metal thin film pattern 55 for forming projections for optical components 56 Optical component mounting pads 56 Optical fiber fixing projections Part 57 projection part 58 of optical component mounting pad part optical fiber 59 second resin layer 60 optical wiring layer 61 second support 62 mirror 63 substrate 64 electric wiring 65 adhesive layer 66 hole 67 land 68 via hole

Claims (3)

An optical / electrical wiring board comprising an optical wiring layer having an optical fiber for propagating an optical signal as an optical wiring on the electric wiring of the substrate having electric wiring,
A mirror provided in a part of the optical fiber;
An optical wiring layer in which an optical fiber is installed on the first resin layer and a second resin layer is installed thereon,
The first resin layer is used to fix the optical fiber, the first resin layer is used to mount the optical component, and the optical component is mounted on the optical component. A pad for an optical component made of metal installed on the upper surface of the optical wiring layer ,
And pads for electric components provided on the top surface of the optical wiring layer for soldering electrical components,
A via hole for electrically connecting with any of the pads of the optical component or the electric components and the electric wiring board,
An electric wiring provided on the optical wiring layer,
An optical / electrical wiring board comprising: A method of manufacturing an optical / electrical wiring board comprising an optical wiring layer having an optical fiber for propagating an optical signal as an optical wiring on the electric wiring of the substrate having electric wiring,
(I) A first resin layer is applied onto the support, and the first resin layer is etched using the metal film as a mask. A protrusion made of one resin layer for mounting an optical component, and a pad using the mask as a metal pad for soldering the optical component on the protrusion for mounting the optical component;
An optical fiber is installed in alignment with the protrusion for fixing the optical fiber, and the optical fiber and the pad are embedded using a second resin layer from above, and the second surface is exposed so that the surface of the pad is exposed. Forming a pad on the upper surface of the optical wiring layer and the optical wiring layer by removing the resin layer of
(Ii) a step of peeling the optical wiring layer from the support;
(Iii) a step of bonding the surface of the optical wiring layer on which the pad is formed and a second support;
(Iv) a step of providing a mirror by forming a 45 ° inclined surface at a desired position of the optical fiber in the optical wiring layer;
(V) bonding the substrate having the electrical wiring and the optical wiring layer;
(Vi) forming a via hole for electrically connecting the electrical wiring on the substrate and the pad;
A method of manufacturing an optical / electrical wiring board, comprising the steps (i) to (vi) described above. A mounting substrate comprising an optical component and / or an electrical component mounted on the optical / electrical wiring substrate according to claim 1 .

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