WO2016084815A1

WO2016084815A1 - Opto-electric hybrid substrate and method for producing same

Info

Publication number: WO2016084815A1
Application number: PCT/JP2015/082965
Authority: WO
Inventors: 直幸田中; 雄一辻田
Original assignee: 日東電工株式会社
Priority date: 2014-11-25
Filing date: 2015-11-25
Publication date: 2016-06-02

Abstract

An opto-electric hybrid substrate 10 which is provided with: an electrical circuit board E wherein an electrical wiring line 2 is formed on the surface of an insulating layer 1; and an optical waveguide W which is provided on the back surface of the insulating layer 1 of the electrical circuit board E, with a metal layer 9 being interposed therebetween. An opening 20 is formed by removing at least a part of a region of the metal layer 9, said region overlapping the outline part of an edge of the optical waveguide W, and the optical waveguide W is formed in such a manner that a part of the optical waveguide W enters into the opening 20. This opto-electric hybrid substrate is able to be used favorably for a long period of time since an edge of the optical waveguide W that is provided on the back surface of the electrical circuit board E is not separated from the metal layer 9.

Description

Opto-electric hybrid board and manufacturing method thereof

The present invention relates to an opto-electric hybrid board in which an electric circuit board and an optical waveguide are laminated, and a manufacturing method thereof.

In recent electronic devices and the like, with the increase in the amount of transmission information, optical wiring has been adopted in addition to electrical wiring, and opto-electric hybrid boards that can simultaneously transmit electrical signals and optical signals are often used. . As such an opto-electric hybrid board, for example, as shown in FIG. 13, an insulating layer 1 made of polyimide or the like is used as a board, and an electric wiring 2 made of a conductive pattern is provided on the surface thereof to form an electric circuit board E. A structure in which an optical waveguide W is provided on the back side through a reinforcing metal layer 9 is known (see, for example, Patent Document 1). The surface of the electric circuit board E is insulated and protected by a cover lay 3. The metal layer 9 is provided with through

holes

5 and 5 ′ for optically coupling an optical element (not shown) mounted on the surface side of the electric circuit board E and the optical waveguide W. The optical waveguide W is composed of three layers: an under cladding layer 6, a core 7 that serves as a light path, and an over cladding layer 8.

Since the metal layer 9 has a different linear expansion coefficient between the insulating layer 1 and the optical waveguide W on the back side, if the two layers are directly laminated, stress or a minute bend occurs in the optical waveguide W due to the ambient temperature. It is provided to avoid an increase in propagation loss. However, in recent years, in response to the trend toward miniaturization and high integration of electronic devices, the above-mentioned opto-electric hybrid board is also flexible so that it can be used in a small space or a movable part such as a hinge part. There is an increasing demand for it. Therefore, also in the opto-electric hybrid board provided with the optical waveguide W through the metal layer 9 as described above, in order to enhance the flexibility, the metal layer 9 itself is partially removed and the optical waveguide is formed in the removed portion. It has been proposed to enhance flexibility by inserting a cladding layer of W (see, for example, Patent Document 2).

JP 2009-265342 A JP 2013-195532 A

Also, recently, in order to further enhance the flexibility of the opto-electric hybrid board, as shown in FIG. 14A when the opto-electric hybrid board is viewed from the optical waveguide W side, both sides serving as an optical coupling part and a connector connection part are provided. Therefore, it is often used that the electric circuit board E is widened and reinforced by the metal layers 9 and 9 ', and the middle part is narrowed.

However, since such a highly flexible opto-electric hybrid board is often pulled or twisted greatly, different stresses are generated between the metal layers 9 and 9 'made of different materials and the optical waveguide W. The stress difference is concentrated at the corners P [the part surrounded by a small circle in FIG. 14A] at both ends of the optical waveguide W, and appears in the form of distortion and warp, and is easily peeled off from this part. It turns out that there is a problem.

Further, as shown in FIG. 14B, in the opto-electric hybrid board of the type not having the

metal layers

9 and 9 ′, both ends of the optical waveguide W are directly arranged on the back surface of the insulating layer 1 such as polyimide. However, even in this case, since the materials are different from each other, the optical waveguide W tends to be easily peeled off from the corner portion P due to the difference in stress. found.

The present invention has been made in view of such circumstances, and the end portion of the optical waveguide provided in an arrangement overlapping the metal layer or the insulating layer on the back side of the electric circuit board may be peeled off from the metal layer or the insulating layer. It is an object of the present invention to provide an opto-electric hybrid board that can be used satisfactorily over a long period of time and a method for producing the same.

In order to achieve the above object, the present invention provides an electric circuit board in which electric wiring is formed on the surface of an insulating layer, and an optical waveguide provided on the back side of the insulating layer of the electric circuit board via a metal layer. And at least one end of the optical waveguide overlaps with the metal layer on the back surface of the electric circuit board in such a manner that the contour of the end of the optical waveguide is inward from the contour of the metal layer. In the metal layer, at least a part of the region overlapping with the contour of the optical waveguide end is removed to form an opening, and the optical waveguide is formed with a part of the optical waveguide entering the opening. The opto-electric hybrid board is a first gist, and in particular, the opto-electric hybrid board in which a plurality of openings of the metal layer are intermittently formed along the contour of the end of the optical waveguide. The substrate is a second gist.

The present invention also provides an opto-electric hybrid device comprising an electric circuit board having electric wiring formed on the surface of an insulating layer, and an optical waveguide provided on the back side of the insulating layer of the electric circuit board via a metal layer. At least one end of the optical waveguide overlaps with the metal layer on the back surface of the electric circuit board in such a manner that the outline of each other overlaps or the outline of the end of the optical waveguide is outside the outline of the metal layer. In the above metal layer, at least a part of the region where the contour of the metal layer itself overlaps the end of the optical waveguide is removed to form an opening, and a part of the optical waveguide enters the opening. The third aspect is an opto-electric hybrid board on which an optical waveguide is formed, and in particular, a plurality of openings of the metal layer are intermittently formed along the contour of the metal layer itself. The opto-electric hybrid board is a fourth gist.

Furthermore, the present invention is an opto-electric hybrid board comprising an electric circuit board having an electrical wiring formed on the surface of an insulating layer, and an optical waveguide provided directly on the back side of the insulating layer of the electric circuit board, At least one end of the optical waveguide overlaps with the insulating layer on the back surface of the electric circuit board in an arrangement in which the contour of the optical waveguide end is inward from the contour of the insulating layer, and the optical waveguide end portion of the insulating layer A fifth aspect is an opto-electric hybrid board in which at least a part of a region overlapping with the contour part of the optical waveguide is formed in the concave part, and the optical waveguide is formed in a part of the optical waveguide in the concave part. In particular, the sixth summary is an opto-electric hybrid board in which a plurality of recesses of the insulating layer are intermittently formed along the contour of the end portion of the optical waveguide.

And, the present invention is an opto-electric hybrid board comprising an electric circuit board in which electric wiring is formed on the surface of an insulating layer, and an optical waveguide provided directly on the back side of the insulating layer of the electric circuit board, At least one end portion of the optical waveguide overlaps with the insulating layer on the back surface of the electric circuit board in such a manner that the contours overlap each other or the contour of the optical waveguide end portion is outside the contour of the insulating layer. Among them, at least a part of the region where the contour of the insulating layer itself overlaps the end of the optical waveguide is formed in the recess, and the optical waveguide is formed in a state where a part of the optical waveguide enters the recess. A mixed substrate is a seventh summary, and in particular, an eighth embodiment is a photoelectric mixed substrate in which a plurality of recesses of the insulating layer are intermittently formed along the contour of the insulating layer itself. To do.

The present invention also provides an opto-electric hybrid board manufacturing method according to the first aspect, wherein an electrical circuit board is prepared in which electrical wiring is formed on the surface of the insulating layer and a metal layer is formed on the back surface of the insulating layer. And a step of forming an optical waveguide with respect to the metal layer on the back surface side of the electric circuit board in a state where at least one end thereof is arranged so that the contour of the end of the optical waveguide is inward from the contour of the metal layer. In the step of preparing the electric circuit board, forming an opening by removing at least a part of the region of the metal layer that overlaps the contour of the optical waveguide end, and in the optical waveguide formation step, The manufacturing method of the opto-electric hybrid board that forms the optical waveguide in a state where a part of the optical waveguide is inserted into the opening of the metal layer is a ninth gist, and in particular, the step of preparing the electric circuit board. In the above The opening of the genus layer, along the contour of the waveguide end portion, intermittently and tenth gist of the opto-electric hybrid board manufacturing method which is adapted to form a plurality.

Furthermore, the present invention provides a method for producing an opto-electric hybrid board according to the third aspect, wherein an electrical circuit board is prepared in which electrical wiring is formed on the surface of the insulating layer and a metal layer is formed on the back surface of the insulating layer. And a state in which the optical waveguide is disposed with respect to the metal layer on the back surface side of the electric circuit board so that at least one end thereof overlaps with each other or the contour of the end of the optical waveguide is outside the contour of the metal layer. In the step of preparing the electric circuit board, an opening is formed by removing at least a part of a region where the contour of the metal layer itself overlaps the end of the optical waveguide. In the optical waveguide forming step, an eleventh aspect is a method for manufacturing an opto-electric hybrid board in which an optical waveguide is formed in a state in which a part of the optical waveguide is inserted into the opening of the metal layer. In particular, the above electricity In the step of preparing a road substrate, the openings of the metal layer, along the contour of the metal layer itself, intermittently and twelfth gist of the opto-electric hybrid board manufacturing method which is adapted to form a plurality.

And this invention is the manufacturing method of the opto-electric hybrid board | substrate which is the said 5th summary, Comprising: The process of preparing the electrical circuit board by which the electrical wiring was formed in the surface of an insulating layer, The said electrical circuit board back surface side Forming the optical waveguide with respect to the insulating layer in a state in which at least one end thereof is arranged in such a manner that the contour of the end of the optical waveguide is inside the contour of the insulating layer, and preparing the electric circuit board Forming a recess in at least a part of a region of the insulating layer that overlaps the contour of the end of the optical waveguide, and in the optical waveguide forming step, allowing a part of the optical waveguide to enter the recess of the insulating layer. The manufacturing method of the opto-electric hybrid board for forming the optical waveguide in a state of being in a state is a thirteenth aspect, and in particular, a plurality of recesses of the insulating layer are intermittently formed along the contour of the end of the optical waveguide. Optoelectric mixing The substrate manufacturing method and fourteenth gist of the.

The present invention also relates to a method for manufacturing an opto-electric hybrid board according to the seventh aspect, the step of preparing an electric circuit board in which electric wiring is formed on the surface of the insulating layer; Forming the optical waveguide with respect to the insulating layer in a state where at least one end of the optical waveguide overlaps each other or the contour of the optical waveguide end is outside the contour of the insulating layer. In the step of preparing the substrate, a recess is formed in at least a part of a region of the insulating layer where the contour of the insulating layer itself overlaps with the end of the optical waveguide. In the optical waveguide forming step, the recess is formed in the recess of the insulating layer. In the fifteenth aspect, a method for producing an opto-electric hybrid board in which an optical waveguide is formed in a state in which a part of the optical waveguide is inserted, and in particular, the concave portion of the insulating layer is formed as a contour portion of the insulating layer itself. Along the line The opto-electric hybrid board manufacturing method which is adapted to form a sixteenth gist of the.

That is, the opto-electric hybrid board according to the present invention has a metal layer or insulating layer overlapping the edge of the optical waveguide on the back side of the electric circuit board, or a contour of the metal layer or insulating layer. The region where the portion overlaps the end of the optical waveguide is partially removed to form a recess (in the case of a metal layer, an opening from which the metal layer has been removed), and a part of the optical waveguide is inserted into the recess It is a thing.

According to this configuration, in the end portion of the optical waveguide that overlaps the back surface of the metal layer or the insulating layer, in the mutual contour portion where stress is concentrated and easily peeled off, a part of the optical waveguide is provided in the metal layer. It enters into the recess or the recess provided in the insulating layer. Therefore, a part of the optical waveguide that has entered the opening or the recess has a so-called anchoring effect, and the optical waveguide is less likely to be peeled than when the flat surfaces are joined to each other.

In particular, since the peel strength at the laminated interface between the metal layer and the optical waveguide is small, the metal layer provided with an opening and a part of the optical waveguide inserted into the opening has a part of the optical waveguide. And it will be in the state joined directly with the insulating layer of the metal layer back side, and the peel strength between both can be enlarged greatly. For this reason, even if the internal stress caused by external load or heat is different between the metal layer and the optical waveguide or the laminated portion of the insulating layer and the optical waveguide, warping or distortion based on the difference in stress is not caused. The optical waveguide end is not affected.

Therefore, in the manufacturing process such as mounting an optical element or the like, the process of incorporating the opto-electric hybrid board into an electronic device or the like, and the actual use, the optical waveguide W is not peeled off from the end portion, This opto-electric hybrid board can be used satisfactorily for a long time.

Also, in the present invention, in particular, the opening of the metal layer or the recess of the insulating layer is along the contour of the optical waveguide end, or along the contour of the metal layer itself or the contour of the insulating layer itself. In the case where a plurality of elements are intermittently formed, the effect of preventing the optical waveguide W from being peeled off is particularly preferable.

And according to the method for producing an opto-electric hybrid board of the present invention, the opto-electric hybrid board of the present invention can be obtained efficiently.

(A) is a partial longitudinal sectional view schematically showing an embodiment of the present invention, (b) is a view taken along the line AA ′ of (a), and (c) is a line BB of (b). It is a cross-sectional view. It is CC 'sectional drawing of FIG.1 (b). (A) to (d) are explanatory views showing steps of producing an electric circuit board in the method for producing an opto-electric hybrid board. (A) to (d) are explanatory views showing the optical waveguide manufacturing process in the method for manufacturing an opto-electric hybrid board. (A), (b) is explanatory drawing which shows the modification of the opening shape of the metal layer in said example. (A)-(f) is explanatory drawing which shows the modification of the opening shape of the metal layer in said example. (A)-(d) is explanatory drawing which shows the modification of the opening shape of the metal layer in said example. It is a partial longitudinal cross-sectional view which shows other embodiment of this invention typically. (A) to (c) are explanatory views showing steps of producing an optical waveguide in the method for producing an opto-electric hybrid board. (A)-(f) is explanatory drawing which shows the modification of the opening shape of the metal layer in other embodiment of this invention. (A)-(e) is explanatory drawing which shows the modification of the opening shape of the metal layer in further another embodiment of this invention. (A) is explanatory drawing which shows other embodiment of this invention, (b), (c) is both explanatory drawing which shows the preparation process. It is a typical longitudinal section showing an example of the conventional opto-electric hybrid board. (A), (b) is explanatory drawing for demonstrating the subject of the conventional opto-electric hybrid board together.

Next, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to this embodiment.

FIG. 1 (a) is a partial longitudinal sectional view schematically showing an embodiment of the opto-electric hybrid board according to the present invention, and FIG. 1 (b) is an AA ′ line in FIG. 1 (a). FIG. 1C is a cross-sectional view taken along the line BB ′ of FIG. 1B. FIG. 2 is a cross-sectional view taken along the line CC ′ of FIG. That is, the opto-electric hybrid board 10 includes an electric circuit board E in which electric wiring 2 is provided on the surface of the insulating layer 1 and an optical waveguide W provided on the back side of the insulating layer 1.

The electric circuit board E has an insulating layer 1 made of polyimide or the like on the surface thereof, an optical element mounting pad 2a, a connector mounting pad 2b, other various element mounting pads, a ground electrode or the like (not shown). The electric wiring 2 including the pad 2a is insulated and protected by a cover lay 3 made of polyimide or the like. Note that the surfaces of the pads 2a and the like that are not protected by the coverlay 3 are covered with an electrolytic plating layer 4 made of gold, nickel, or the like.

On the other hand, the optical waveguide W provided on the back surface side of the insulating layer 1 has a substantially rectangular shape elongated in the left-right direction in plan view, and the undercladding layer 6 and its surface [lower surface in FIG. 1 (a)]. The core 7 is formed in a predetermined pattern, and the over clad layer 8 is integrated with the surface of the under clad layer 6 in a state of covering the core 7.

And the part of the core 7 corresponding to the optical element mounting pad 2a of the electric circuit board E is formed on an inclined surface of 45 ° with respect to the extending direction of the core 7. This inclined surface is a light reflecting surface 7a, which changes the direction of the light propagated in the core 7 by 90 ° to enter the light receiving portion of the optical element, or conversely, exits from the light emitting portion of the optical element. The direction of the emitted light is changed by 90 ° to enter the core 7.

Further, a metal layer 9 for reinforcing the opto-electric hybrid board 10 is provided between the electric circuit board E and the optical waveguide W, and both side parts excluding an intermediate part where flexibility is required [see FIG. 14 (a)], the pattern is formed so as to partially overlap the both ends of the optical waveguide W. A through hole 5 for securing an optical path between the core 7 of the optical waveguide W and the optical element is formed in the metal layer 9. The under cladding layer 6 is also formed in the through hole 5. Has entered.

Furthermore, as shown in FIG. 1B, the metal layer 9 has two side portions along the longitudinal direction of the optical waveguide W in the region of the metal layer 9 that overlaps the contour of the optical waveguide W. A part of each part is partially removed to form a total of four openings 20 having a rectangular shape in plan view. Then, as shown in FIGS. 1C and 2, the under cladding layer 6 enters the openings 20, and the inserted under cladding layer 6 and the insulating layer 1 are directly and firmly bonded. is doing. This is the greatest feature of the present invention. In FIG. 1B, illustration of the through hole 5 is omitted, and a portion where the metal layer 9 is formed is indicated by a diagonally downward slanting line with a large interval (the same applies to the following drawings).

Further, in FIGS. 1A, 1B, and 2, the right-side portion of the opto-electric hybrid board 10 is symmetrical with the left-side portion shown in the drawing. Since they are the same, their illustration and description are omitted.

Next, a method for producing the opto-electric hybrid board 10 will be described (see FIGS. 3 and 4).

First, a flat metal layer 9 is prepared, a photosensitive insulating resin made of polyimide or the like is applied to the surface, and an insulating layer 1 having a predetermined pattern is formed by a photolithography method (see FIG. 3A). ]. The thickness of the insulating layer 1 is set within a range of 3 to 50 μm, for example. Examples of the material for forming the metal layer 9 include stainless steel, copper, silver, aluminum, nickel, chromium, titanium, platinum, and gold. Among them, stainless steel is preferable from the viewpoint of rigidity and the like. Further, although the thickness of the metal layer 9 depends on the material, it is set within a range of 10 to 70 μm, for example, when stainless steel is used. That is, if the thickness is less than 10 μm, the reinforcing effect may not be sufficiently obtained. On the other hand, if the thickness exceeds 70 μm, the distance of light traveling through the through hole 5 of the metal layer 9 becomes long, and the light loss may increase. Because there is.

Next, as shown in FIG. 3B, the surface of the insulating layer 1 includes electrical wiring 2 (optical device mounting pads 2a, connector pads 2b, other pads, ground electrodes, etc. The same) is formed by, for example, a semi-additive method. In this method, first, a metal film (not shown) made of copper, chromium, or the like is formed on the surface of the insulating layer 1 by sputtering or electroless plating. This metal film becomes a seed layer (layer serving as a base for forming an electrolytic plating layer) when performing subsequent electrolytic plating. Then, after laminating a photosensitive resist (not shown) on both surfaces of the laminate composed of the metal layer 9, the insulating layer 1 and the seed layer, a photo resist is applied to the photosensitive resist on the side where the seed layer is formed. A hole portion of the pattern of the electric wiring 2 is formed by lithography, and the surface portion of the seed layer is exposed at the bottom of the hole portion. Next, an electrolytic plating layer made of copper or the like is laminated on the surface portion of the seed layer exposed to the bottom of the hole by electrolytic plating. Then, the photosensitive resist is removed with an aqueous sodium hydroxide solution or the like. Thereafter, the portion of the seed layer where the electrolytic plating layer is not formed is removed by soft etching. The laminated portion composed of the remaining seed layer and electrolytic plating layer is the electric wiring 2.

Next, as shown in FIG. 3 (c), a photosensitive insulating resin made of polyimide or the like is applied to the portion of the electrical wiring 2 excluding a part of the optical element mounting pad 2 and the connector pad 2b. The cover lay 3 is formed by photolithography.

Then, as shown in FIG. 3 (d), the electrolytic plating layer 4 is formed on the surface of the optical element mounting pad 2a and the part of the connector pad 2b which are not covered with the cover lay 3. In this way, the electric circuit board E is formed.

Next, a photosensitive resist is laminated on both sides of the laminate composed of the metal layer 9 and the electric circuit board E, and then the back side of the metal layer 9 (the side opposite to the electric circuit board E) is exposed. Of the conductive resist, a portion where the metal layer 9 is not required, a portion corresponding to the portion where the optical path through hole 5 is to be formed [see FIG. 1A], and further, the portion where the opening 20 is to be formed (see FIG. 2), a hole is formed by photolithography, and the back surface of the metal layer 9 is partially exposed.

Then, the exposed portion of the metal layer 9 is etched using an aqueous solution for etching corresponding to the metal material of the metal layer 9 (for example, the aqueous solution for etching when the metal layer 9 is a stainless steel layer is ferric chloride aqueous solution). Then, the insulating layer 1 is exposed from the trace of the removal, and then the photosensitive resist is peeled off with an aqueous sodium hydroxide solution or the like. As a result, as shown in FIG. 4A, the metal layer 9 is formed only in the region that needs reinforcement, and the optical path through hole 5 [see FIG. 1A] and a part of the optical waveguide W are formed. Are simultaneously formed.

Next, in order to form the optical waveguide W [see FIG. 1A] on the back surface of the insulating layer 1 (the back surface of the metal layer 9 in the portion where the metal layer 9 is formed), first, FIG. 4 (b), after applying a photosensitive resin, which is a material for forming the undercladding layer 6, to the back surface (the lower surface in the figure) of the insulating layer 1 and the metal layer 9, the applied layer is irradiated with irradiation rays. The under clad layer 6 is formed by exposing and curing. The under cladding layer 6 is formed in a predetermined pattern by a photolithography method. Then, the under cladding layer 6 fills the optical path through hole 5 of the metal layer 9 [see FIG. 1A]. A part of the under cladding layer 6 also enters the opening 20 of the metal layer 9 and is in a state of being directly bonded to the back surface of the insulating layer 1. The thickness of the under cladding layer 6 (thickness from the back surface of the insulating layer 1) is usually set to be thicker than the thickness of the metal layer 9. A series of operations for forming the optical waveguide W is performed with the back surface of the insulating layer 1 on which the metal layer 9 is formed facing upward, but is shown as it is in the drawing.

Next, as shown in FIG. 4C, a core 7 having a predetermined pattern is formed on the surface (lower surface in the figure) of the under cladding layer 6 by photolithography. The thickness of the core 7 is set within a range of 3 to 100 μm, for example, and the width is set within a range of 3 to 100 μm, for example. Examples of the material for forming the core 7 include the same photosensitive resin as that for the under cladding layer 6, and a material having a higher refractive index than the material for forming the under cladding layer 6 and an over cladding layer 8 described later is used. It is done. The adjustment of the refractive index can be performed, for example, by selecting the types of forming materials of the under cladding layer 6, the core 7, and the over cladding layer 8 and adjusting the composition ratio.

Next, as shown in FIG. 4D, the over clad layer 8 is formed by photolithography so as to be overlaid on the surface (the lower surface in the figure) of the under clad layer 6 so as to cover the core 7. In this way, the optical waveguide W is formed. Note that the thickness of the over cladding layer 8 (thickness from the surface of the under cladding layer 6) is set to be not less than the thickness of the core 7 and not more than 300 μm, for example. Examples of the material for forming the over cladding layer 8 include the same photosensitive resin as that for the under cladding layer 6.

Incidentally, a specific composition example of the material for forming the optical waveguide W is shown below.
<Formation material of under cladding layer 6 and over cladding layer 8>
Epoxy resin containing alicyclic skeleton (manufactured by Daicel Chemical Industries, EHPE3150) 20 parts by weight liquid long-chain bifunctional semi-aliphatic epoxy resin (DIC, EXA-4816) 80 parts by weight photoacid generator (manufactured by ADEKA) SP170) 2 parts by weight ethyl lactate (manufactured by Musashino Chemical Laboratory) 40 parts by weight <Formation material of core 7>
o-cresol novolac glycidyl ether (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., YDCN-700-10) 50 parts by weight bisphenoxyethanol fluorenediglycidyl ether (manufactured by Osaka Gas Chemical Co., Ltd., OGSOL EG) 50 parts by weight photoacid generator (ADEKA) Made by SP170) 1 part by weight ethyl lactate (Musashino Chemical Laboratory Co., Ltd.) 50 parts by weight

Next, an inclined surface inclined by 45 ° with respect to the extending direction of the core 7 is formed in a predetermined portion of the optical waveguide W by laser processing, cutting processing, or the like, and is mounted on the surface side of the electric circuit board E. A reflection surface 7a [see FIG. 1A] for optical coupling with the element is used. Then, necessary members are attached, such as mounting an optical element on the pad 2a of the electric wiring 2 provided on the surface side of the electric circuit board E.

Thus, the opto-electric hybrid board 10 shown in FIG. 1 can be obtained. In this opto-electric hybrid board 10, a region of the metal layer 9 that overlaps the end of the optical waveguide W on the back surface side of the electric circuit board E is partially removed so that the region overlapping the contour of the optical waveguide W is partially removed. A plurality of openings 20 are formed, and the underclad layer 6 of the optical waveguide W enters the openings 20 and is directly bonded to the insulating layer 1.

Therefore, according to this configuration, in the laminated portion of the metal layer 9 and the optical waveguide W, a force for peeling off the optical waveguide W works because the internal stress caused by external load or heat is different between the two. However, since the contour portion of the end portion of the optical waveguide W is partially bonded directly to the insulating layer 1, the peel strength at the bonded portion is high, and the peel strength as a whole is very high. Therefore, the optical waveguide W is not peeled off from the end portion in the manufacturing process such as mounting an optical element or the like, the process of incorporating the opto-electric hybrid board 10 into an electronic device, and the like. The opto-electric hybrid board 10 can be used satisfactorily for a long time.

In addition, the opto-electric hybrid board 10 only needs to be patterned so that the opening 20 is formed in a predetermined portion overlapping the end contour of the optical waveguide W when patterning the metal layer 9. There is an advantage that a special process is not required and can be obtained easily, and manufacturing efficiency is good.

In order to compare the difference in peel strength between the case where the metal layer 9 and the optical waveguide W are bonded and the case where the insulating layer 1 and the optical waveguide W are directly bonded, the following test was performed. .

<Peel strength test>
A stainless steel plate (manufactured by Nippon Steel Co., Ltd., SUS304, thickness 0.02 mm) is prepared as a metal layer of the opto-electric hybrid board, and the thickness of the under cladding layer is formed on the surface using the optical waveguide W forming material described above. A pseudo optical waveguide having a three-layer structure of 25 μm, a core thickness of 50 μm, and an over cladding layer thickness of 25 μm was formed (Sample 1). Further, as the insulating layer of the opto-electric hybrid board, polyimide (manufactured by Nitto Denko Corporation, thickness 0.01 mm) is formed on the metal layer, and the pseudo optical waveguide is formed on the surface where the metal layer is etched in the same manner as described above. Formed (Sample 2).

Then, in

Samples

1 and 2, the 90 ° peel strength when peeling the pseudo optical waveguide was measured according to the test method of JIS C 5016: 1994. As a result, the peel strength of sample 1 (base is stainless steel plate) is 0.209 N / cm (21.3 g / cm), and the peel strength of sample 2 (base is polyimide) is 1.986 N / cm (202.6 g). / Cm).

Therefore, as shown in the above example, it can be seen that, when a part of the optical waveguide W is directly joined to the insulating layer 1, it is possible to provide the optical waveguide W with very excellent peeling prevention performance.

In the above example, when the opening 20 is formed in the metal layer 9, an outline of the end portion of the optical waveguide W overlapping the metal layer 9 by the opening 20 [zigzag line X in FIG. It is preferable that 5 to 95% of the entire length of the insulating layer 1 is in direct contact with the back surface of the insulating layer 1. That is, if the ratio of the contour line in contact with the back surface of the insulating layer 1 by the opening 20 is smaller than the above range, the effect of preventing the optical waveguide W from being peeled may not be sufficiently obtained. If it is larger, depending on the structure of the opto-electric hybrid board 10, there is a possibility that the reinforcement by the metal layer 9 may be insufficient, which is not preferable.

The shape of the opening 20 is not limited to the above example. For example, as shown in FIGS. 5A and 5B, a plurality of strip-shaped openings 20 are arranged in parallel. By arranging it, the opening can be intermittently overlapped with the portion overlapping the contour portion of the optical waveguide W.

Further, in the example shown in FIG. 1, four openings 20 are provided in the metal layer 9 along the outline of the optical waveguide W. For example, as shown in FIG. Of the portions, the opening 20 may be provided only in two portions overlapping the two corners of the tip. This is because, if the optical waveguide W and the insulating layer 1 are directly bonded with high peel strength at least at the two corners, this portion can be prevented from peeling off and can be used satisfactorily. Further, as shown in FIG. 6 (b), when openings 20 are provided in a total of three locations, two portions that overlap two corners of the tip and a portion that overlaps the edge of the optical waveguide W between them. Further, the effect of preventing peeling of the edge portion of the optical waveguide W can be further increased.

Alternatively, as shown in FIG. 6C, the shape of the opening 20 provided in the metal layer 9 (planar view shape, hereinafter the same) is formed in two strips along both edges extending in the longitudinal direction of the optical waveguide W. Alternatively, as shown in FIG. 6 (d), it can be formed into a single band shape having two corners along the end contour portion of the optical waveguide W.

In addition, when the opening 20 is formed in the portion of the optical waveguide W that overlaps with the two corners at the end of the end, the shape of the two openings 20 is along the corner as shown in FIG. It can be made into a bent shape or a round shape as shown in FIG.

Furthermore, even if the shape of the two openings 20 is a rectangular shape with rounded corners as shown in FIG. 7A, the shape of the optical waveguide W is as shown in FIG. 7B. A belt-like shape extending obliquely with respect to the corner may be used. Further, it may be triangular as shown in FIGS.

As described above, the shape of the opening 20 is effective in preventing peeling of the end portion of the optical waveguide W while considering the balance between the region where the metal layer 9 is desired to be rigid and the region where the flexibility is desired. It can be set in various forms.

In the above example, the opening 20 is provided in the metal layer 9 so that a part of the optical waveguide W enters the opening 20. However, the opening 20 is removed by removing a part of the metal layer 9. 8, for example, as shown in FIG. 8, the insulating layer 1 exposed by the opening 20 is further processed into a concave shape to form a concave portion 21, and the step is deepened. The peel strength can be further increased. According to this configuration, the end portion of the optical waveguide W becomes more difficult to be peeled off, and more excellent durability is exhibited.

The process of making the insulating layer 1 concave can be performed, for example, as follows. That is, first, as shown in FIG. 9A, the electric circuit board E is formed in the same manner as in the above example, and the opening 20 and the optical coupling through hole 5 are formed in the metal layer 9 on the back surface side. (See FIG. 1). And as shown in FIG.9 (b), by performing the alkali etching in the state which protected the other part with respect to the part of the insulating layer 1 exposed from the opening part 20 of the said metal layer 9, the recessed part 21 is carried out. Form. Then, as shown in FIG. 9 (c), after forming the optical waveguide W in the same manner as in the above example, mounting the optical element or the like, forming the reflective surface 7a, etc. A substrate can be obtained.

However, the depth of the recess 21 is preferably set to be 5 to 70% of the entire thickness of the insulating layer 1 (for example, when the entire thickness of the insulating layer 1 is 10 μm, the recess 21 is formed by etching). It is preferable to form the recess 21 so that the thickness of the insulating layer 1 in the portion is 3 to 9.5 μm). That is, if the concave portion 21 is too shallow, even if the concave portion 21 is provided, there is no difference in the effect of preventing the optical waveguide W from peeling off. Conversely, if the concave portion 21 is too deep, the insulating layer 1 is torn from that portion. There is a risk of malfunction, which is not preferable.

Note that the method of processing the insulating layer 1 into a concave shape is not limited to the above-described method. For example, the insulating layer 1 exposed from the opening 20 of the metal layer 9 in the stage shown in FIG. On the other hand, by irradiating YAG laser or excimer laser, a predetermined region on the back surface (lower surface in FIG. 9) of the insulating layer 1 may be melted and removed by a predetermined thickness to obtain the recess 21.

Further, in the above series of examples, the end portion of the optical waveguide W is provided so as to overlap the metal layer 9 having a wide width on both sides of the opto-electric hybrid board 10. Although this is an example in which the contour of the end portion is on the inside, the present invention can also be applied to a strip-like substrate in which the opto-electric hybrid board 10 has the same width throughout. Also, the present invention can be applied to the case where the metal layer 9 and the end portion of the optical waveguide W overlap each other or the contour of the end portion of the optical waveguide W is outside the contour of the metal layer 9. it can. In these cases as well, in the portion where the end portion of the optical waveguide W and the end portion of the metal layer 9 overlap, a part of the metal layer 9 is removed by an appropriate arrangement to form the opening 20, thereby providing the optical waveguide. The effect of preventing the peeling of W can be obtained.

Incidentally, FIG. 10A shows an example of the case where the metal layer 9 and the end of the optical waveguide W are arranged in a state where the outlines of the metal layer 9 and the optical waveguide W substantially overlap each other. In this example, for easy understanding, the outline of the optical waveguide W is shown to be slightly inside the outline of the metal layer 9 [the same is true for the figures after (b) in FIG. 10]. In this example, in the contour of the end portion of the optical waveguide W and the metal layer 9 in which the contours are substantially overlapped, two corners at the tip are notched to form an opening 20 ′. According to this configuration, since the two corners at the tip of the optical waveguide W are directly joined to the insulating layer 1, peeling of the tip portion of the optical waveguide W is effectively prevented. Therefore, in the present invention, the “opening” formed in the metal layer 9 includes not only an opening surrounded by four sides but also a notch formed by cutting out the edge of the metal layer 9. It is a purpose to include.

In the case where the metal layer 9 and the end of the optical waveguide W are arranged in the same manner as described above, as shown in FIG. It is also possible to completely remove the three-direction portions on both side edges along the longitudinal direction of the waveguide W to form the opening 20 ′. Furthermore, as shown in FIG. 10 (c), it is possible to remove only the tip edge portion of the contour portion of the metal layer 9 to form the opening portion 20 '.

Alternatively, the edge portion of the metal layer 9 is not completely removed at the edge portion, but as shown in FIG. Even in this case, the effect of preventing the optical waveguide W from peeling off can be sufficiently obtained. That is, since the bonding strength of the optical waveguide W at the opening 20 ′ is increased, the degree of freedom of the optical waveguide W is limited at both ends where the opening 20 ′ is not formed. This is because the optical waveguide W is difficult to peel off even when the metal layer 9 is interposed.

Similarly, as shown in FIG. 10E, both edge portions along the longitudinal direction of the optical waveguide W are removed from the contour portion of the metal layer 9 in such a manner that both end portions are left, and the opening 20 ′, Or as shown in FIG. 10 (f), the opening 20 ′ may be formed by removing the edge portions on both sides along the longitudinal direction of the optical waveguide W leaving the end portions on the tip side. .

Further, depending on the opto-electric hybrid board 10, the contour portion of the optical waveguide W may be outside the contour portion of the electric circuit board E. Also in that case, the end portion of the optical waveguide W can be made difficult to peel off by cutting out a predetermined portion of the metal layer 9 to form the opening 20 ', as in the above series of examples. For example, as shown in FIG. 11A, when the contour portion of the end portion of the optical waveguide W overlaps with the contour of the electric circuit board E, it is inside the contour of the end portion of the optical waveguide W. Of the contour portion of the metal layer 9, the front edge portion and the three side portions along the longitudinal direction of the optical waveguide W are completely removed to form an opening 20 ′, whereby the optical waveguide W The end can be made difficult to peel off. In this example, the tip of the optical waveguide W is disposed outside the tip of the electric circuit board E. For example, as shown in FIG. 11B, the tip of the electric circuit board E and the optical waveguide W Even in the case where the tips are substantially overlapped or the tip of the optical waveguide W is inside, as in the case of FIG. 11A, the three-direction portions are completely removed from the contour portion of the metal layer 9. Thus, the opening 20 'can be formed.

Further, as shown in FIG. 11C, the tip of the optical waveguide W is arranged outside the tip of the electric circuit board E, and both side edges in the longitudinal direction are substantially overlapped or the optical waveguide W enters the inside. Even in the case where the optical waveguide W is present, as in the case of FIGS. 11A and 11B, the optical waveguide W is obtained by completely removing the three-direction portions of the contour portion of the metal layer 9 to form the opening 20 ′. It is possible to make it difficult to peel off the end of the.

Further, as shown in FIG. 11 (d), two corners at the tip of the metal layer 9 are cut out to form an opening 20 ', and the outline of the optical waveguide W is formed in these openings 20'. A part of the optical waveguide W may be directly joined to the insulating layer 1, and the contour part of the optical waveguide W overlapping the contour part of the metal layer 9 may be disposed outside the contour part of the electric circuit board E.

Further, as shown in FIG. 11 (e), in the same manner as described above, two corners at the tip of the metal layer 9 are cut out to form openings 20 ', and optical waveguides are formed in these openings 20'. A part of the W contour may be directly joined to the insulating layer 1, and the contour of the optical waveguide W overlapping the contour of the insulating layer 1 may be disposed outside the contour of the electric circuit board E.

In the above-described example of the series of openings 20 ', a plurality of strip-shaped openings 20' may be formed in parallel as in the examples shown in FIGS. 5 (a) and 5 (b). Further, a plurality of openings 20 ′ having a small area may be formed along the contour portion of the metal layer 9 at a predetermined interval.

Then, as in the above series of examples, the end portion of the optical waveguide W and the metal layer 9 overlap with each other such that the contours of the optical waveguide W overlap each other or the contour of the end portion of the optical waveguide W is outside the contour of the metal layer 9. In this case, it is preferable that the planar view shape of the metal layer 9 overlapping the optical waveguide W is a rounded shape without corners. This is because the rounded shape provides a stress relaxation effect at the boundary between the portion with and without the metal layer 9.

The present invention is also applied to an opto-electric hybrid board 10 in which the metal layer 9 is not provided and the optical waveguide W directly overlaps the back surface of the insulating layer 1 as shown in FIG. be able to. That is, although the laminated portion of the insulating layer 1 and the optical waveguide W is also a resin-to-resin connection, the optical waveguide W may be warped or distorted and easily peeled off due to the difference in stress. Therefore, in order to further increase the peel strength of the both, as shown in the drawing, a recess 22 is formed on the back surface of the insulating layer 1 overlapping the optical waveguide W, and a part of the optical waveguide W enters the recess 22. can do. The arrangement of the recesses 22 can be formed according to the arrangement of the

openings

20 and 20 '.

According to this configuration, since a throwing effect is obtained with respect to the insulating layer 1 when a part of the optical waveguide W enters, the peel strength compared to the case where the bonding surface of the insulating layer 1 and the optical waveguide W is flat. Is further increased, and a further effect of preventing the optical waveguide W from peeling off can be obtained.

In order to form the recess 22 in the insulating layer 1, for example, as shown in FIG. 12B, after the electric circuit board E is formed in the same manner as in the above example, the back surface of the insulating layer 1 is formed. The concave portion 22 can be formed by performing alkali etching in a state where the portion other than the portion where the concave portion 22 is to be formed is protected. Then, as shown in FIG. 12 (c), after forming the optical waveguide W in the same manner as in the above example, mounting the optical element and the like, forming the reflective surface 7a, etc. A substrate can be obtained. The depth of the concave portion 22 is preferably set to 5 to 70% of the thickness of the insulating layer 1 for the same reason as that for forming the concave portion 21 described above.

Of course, the recess 22 can be formed in a predetermined pattern by irradiating the back surface of the insulating layer 1 with a YAG laser or an excimer laser instead of forming the recess 22 by alkali etching.

Further, in the above example, the photoelectric coupling portions are provided on the left and right sides, and the left and right are symmetrical structures, but the photoelectric coupling portion is provided only on one side, and the other is simply a connector connection. It doesn't matter if it's just down. In that case, it is preferable to apply the shape of the present invention to the end portion of the optical waveguide W which is used for the photoelectric coupling.

Further, in the above series of examples, the outer shape of the optical waveguide W is formed by both the under cladding layer 6 and the over cladding layer 8, but the outer shape of the optical waveguide W is formed only by the over cladding layer 8. It may be a thing formed only with the core 7, even if it is a thing.

In addition, although the specific form in this invention was shown in the said embodiment, the said embodiment is only a mere illustration and is not interpreted limitedly. Various modifications apparent to those skilled in the art are all intended to be within the scope of this invention.

The present invention can be used for an excellent opto-electric hybrid board that can be used safely for a long period of time because the optical waveguide is hardly peeled off from the back side of the electric circuit board portion.

E Electrical circuit board W Optical waveguide 1 Insulating layer 2 Electrical wiring 9 Metal layer 10 Opto-electric hybrid board 20 Opening

Claims

An opto-electric hybrid board comprising: an electric circuit board having electric wiring formed on a surface of an insulating layer; and an optical waveguide provided on the back side of the insulating layer of the electric circuit board via a metal layer, At least one end of the optical waveguide overlaps with the metal layer on the back surface of the electric circuit board in an arrangement in which the contour of the end of the optical waveguide is inward from the contour of the metal layer. An opto-electric hybrid board characterized in that an opening is formed by removing at least a part of a region overlapping with the contour part, and the optical waveguide is formed in a state where a part of the optical waveguide enters the opening. .
The opto-electric hybrid board according to claim 1, wherein a plurality of openings of the metal layer are formed intermittently along the contour of the end of the optical waveguide.
An opto-electric hybrid board comprising: an electric circuit board having electric wiring formed on a surface of an insulating layer; and an optical waveguide provided on the back side of the insulating layer of the electric circuit board via a metal layer, At least one end of the optical waveguide overlaps with the metal layer on the back surface of the electric circuit board in such a manner that the outline of each other overlaps or the outline of the end of the optical waveguide is outside the outline of the metal layer. An opening is formed by removing at least a part of the region where the contour of the metal layer itself overlaps the end of the optical waveguide, and the optical waveguide is formed with a part of the optical waveguide entering the opening. An opto-electric hybrid board.
The opto-electric hybrid board according to claim 3, wherein a plurality of openings of the metal layer are intermittently formed along the contour of the metal layer itself.
An opto-electric hybrid board comprising: an electric circuit board having an electrical wiring formed on a surface of an insulating layer; and an optical waveguide provided directly on the back side of the insulating layer of the electric circuit board, wherein at least one end of the optical waveguide The region overlaps with the insulating layer on the back surface of the electric circuit board in an arrangement in which the contour of the optical waveguide end portion is inward from the contour of the insulating layer, and the region of the insulating layer overlaps with the contour portion of the optical waveguide end portion. An optical / electrical hybrid substrate, wherein an optical waveguide is formed in a state in which at least a part of the optical waveguide is formed in a recess, and a part of the optical waveguide enters the recess.
6. The opto-electric hybrid board according to claim 5, wherein a plurality of recesses of the insulating layer are intermittently formed along a contour portion of an end portion of the optical waveguide.
An opto-electric hybrid board comprising: an electric circuit board having an electrical wiring formed on a surface of an insulating layer; and an optical waveguide provided directly on the back side of the insulating layer of the electric circuit board, wherein at least one end of the optical waveguide Are overlapped with the insulating layer on the back surface of the electric circuit board in such a manner that the outline of each other overlaps or the outline of the end of the optical waveguide is outside the outline of the insulating layer. Of the insulating layers, the insulating layer itself An opto-electric hybrid mounting characterized in that at least a part of the region where the contour part overlaps with the end part of the optical waveguide is formed in the concave part, and the optical waveguide is formed in a state where a part of the optical waveguide enters the concave part substrate.
The opto-electric hybrid board according to claim 7, wherein a plurality of the recesses of the insulating layer are intermittently formed along the contour of the insulating layer itself.
A method for producing an opto-electric hybrid board according to claim 1, comprising the step of preparing an electric circuit board in which electric wiring is formed on the surface of the insulating layer and a metal layer is formed on the back surface of the insulating layer, and the electric circuit board. Preparing the electric circuit board with a step of forming an optical waveguide with respect to the metal layer on the back side in a state where at least one end portion thereof is disposed so that the contour of the optical waveguide end portion is inside the contour of the metal layer. Forming an opening by removing at least a part of a region of the metal layer that overlaps the contour of the end of the optical waveguide. In the optical waveguide forming step, an optical waveguide is formed in the opening of the metal layer. A method for producing an opto-electric hybrid board, wherein an optical waveguide is formed with a part of the waveguide inserted.
10. The method of manufacturing an opto-electric hybrid board according to claim 9, wherein, in the step of preparing the electric circuit board, a plurality of openings of the metal layer are intermittently formed along a contour part of an end portion of the optical waveguide.
A method for producing an opto-electric hybrid board according to claim 3, wherein a step of preparing an electric circuit board in which an electric wiring is formed on the surface of the insulating layer and a metal layer is formed on the back surface of the insulating layer, and the electric circuit board Forming the optical waveguide with respect to the metal layer on the back side in a state where at least one end thereof is arranged such that the outline of each other overlaps or the outline of the end of the optical waveguide is outside the outline of the metal layer, In the step of preparing the electric circuit board, an opening is formed by removing at least a part of a region of the metal layer where the contour portion of the metal layer itself overlaps the end of the optical waveguide. A method for producing an opto-electric hybrid board, wherein an optical waveguide is formed in a state where a part of the optical waveguide is inserted into the opening of the metal layer.
12. The method of manufacturing an opto-electric hybrid board according to claim 11, wherein in the step of preparing the electric circuit board, a plurality of openings of the metal layer are intermittently formed along the contour of the metal layer itself.
A method for producing an opto-electric hybrid board according to claim 5, wherein a step of preparing an electric circuit board in which electric wiring is formed on the surface of the insulating layer; and an optical waveguide for the insulating layer on the back side of the electric circuit board, And forming the electric circuit board in a state in which at least one end thereof is disposed in such a manner that the contour of the end portion of the optical waveguide is inward from the contour of the insulating layer. A recess is formed in at least a part of a region that overlaps the contour of the end, and in the optical waveguide forming step, the optical waveguide is formed in a state where a part of the optical waveguide is inserted into the recess of the insulating layer. A method for producing an opto-electric hybrid board.
14. The method for producing an opto-electric hybrid board according to claim 13, wherein a plurality of recesses of the insulating layer are intermittently formed along the contour of the end of the optical waveguide.
The method for producing an opto-electric hybrid board according to claim 7, wherein a step of preparing an electric circuit board in which electric wiring is formed on the surface of the insulating layer, and an optical waveguide with respect to the insulating layer on the back side of the electric circuit board, In the step of preparing the electric circuit board, wherein at least one end portion is formed in a state in which the contours overlap each other or the contour of the optical waveguide end portion is located outside the contour of the insulating layer, A recess is formed in at least a part of a region of the insulating layer where the contour of the insulating layer itself overlaps with the end of the optical waveguide. In the optical waveguide forming step, a part of the optical waveguide is placed in the recess of the insulating layer. A method for producing an opto-electric hybrid board, characterized in that an optical waveguide is formed in a state of being inserted.
The method for producing an opto-electric hybrid board according to claim 15, wherein a plurality of concave portions of the insulating layer are intermittently formed along a contour portion of the insulating layer itself.