JP5434433B2 - Optical substrate and manufacturing method thereof - Google Patents

Description

The present invention relates to an optical substrate having electrical wiring and optical wiring, and a method for manufacturing the same.

With the advancement of advanced information technology in recent years, the performance improvement of information processing devices such as routers and servers used for information communication has progressed remarkably, and further speeding up of communication signals is required in these devices. . In this speeding up, the communication quality of the electrical wiring in the electronic circuit or the electric circuit becomes an obstacle to improving the performance, so that this obstacle cannot be ignored in increasing the communication speed.
Therefore, optical wiring that can transmit and receive information at high transmission speeds using optical signals is a promising technology for solving problems that hinder high-speed communication, including faster processing signals and reduced electrical noise. The technology using is attracting attention. In particular, in order to realize high-capacity optical interconnection using optical wiring, high-density optical wiring and low-loss connection are important, and various technical studies have been conducted for higher performance and cost reduction. Yes.

  The optical signal is diffused when output from the light emitting element or the optical wiring. For this reason, it is necessary to connect the optical signal connection components at intervals as close as possible. Further, since the optical signal leaks and loses when the connection position of the optical connection is shifted, it is necessary to accurately connect the positions. In addition, since the optical waveguide for propagating the optical signal is provided in the horizontal direction in the substrate plane, it is necessary to convert the optical signal path by approximately 90 ° in order to input / output the optical signal to / from the light emitting / receiving surface of the light emitting / receiving element. is there.

As a method of incorporating optical wiring onto an electronic substrate, there is a method of mounting on a substrate a photoelectric module in which optical wiring, an element that converts light into electricity, a control unit of the element, and the like are collected together. Various methods for manufacturing such an optical substrate have been proposed.
As an optoelectric module, for example, in an optical circuit component described in Patent Document 1, a submount substrate on which a light emitting / receiving element is mounted is mounted on an electronic substrate having an optical wiring provided with a mirror that deflects light at an end face by approximately 90 °. A method for alignment mounting is disclosed. However, in the method of Patent Document 1, a step of mounting the light emitting / receiving element on the submount substrate, a step of forming an opening for disposing a resin layer for optically connecting the light emitting / receiving element and the optical wiring, etc. All of them are difficult to carry out with high accuracy, the manufacturing yield is lowered, and the cost reduction is also difficult.

  For example, in the optical module described in Patent Document 2, a VCSEL mounting pad, an LSI mounting pad, and an optical waveguide are formed on a substrate, a spacer is disposed between the VCSEL and the optical waveguide, and the upper surface of the optical waveguide is Although a configuration in which a VCSEL light emitting surface is mounted as a reference surface is disclosed, in this case, the entire surface of the substrate including the light emitting and receiving elements and the LSI is transferred by a versatile and highly reliable transfer mold method. Batch sealing is not possible. This is because there is an optical waveguide on the mold surface, and it can be mentioned that general optical waveguide materials often cannot withstand the heat generated during the transfer molding process.

  As another reason that the optical waveguide cannot be transfer-molded, the transfer molding resin is generally a black epoxy-based thermosetting resin containing a metal filler, so that the optical signal is scattered. When connecting an optical waveguide to a substrate, there are problems such as resin leaking from the gap if there are irregularities between the substrate and the mold for molding.

JP-A 63-266407 JP 2003-215371 A

  The present invention has been made in view of such conventional problems, and provides an optical substrate capable of connecting an optical waveguide, a light emitting / receiving element, and a light emitting / receiving element control element with high accuracy and low cost, and a method for manufacturing the same. For the purpose.

An optical substrate according to the present invention is mounted on a substrate made of an insulating resin layer having electrical wiring patterned on the front and back, via holes connecting the electrical wiring on the front and back of the substrate, light emitting and receiving elements provided on the substrate, and electrical wiring. An optical substrate having a light emitting / receiving element control element and an optical waveguide provided on the substrate and provided with an optical path conversion mirror on the end surface, wherein the light emitting / receiving element and the optical waveguide are arranged on the substrate with a step. It is joined so as to be optically connected via the optical path conversion mirror, and the connection portion with the electrical wiring of the light emitting / receiving element and the optical path conversion mirror of the optical waveguide are sealed with the first sealing resin, connection of an electrical wiring of the optical element control element is sealed by a second sealing resin, the first sealing resin rather than a melting temperature lower second sealing resin, the optical path conversion mirror Metal film on the back of the light input / output unit And it is provided.
According to the present invention, since the light emitting / receiving element and the optical waveguide are provided with a step on the substrate, when the optical waveguide is optically connected to the light receiving / emitting element, the relative step of the optical waveguide is set on the substrate. By installing it on one side of the part that has it, the light input / output part can be optically opposed to the light emitting / receiving surface of the light emitting / receiving element installed on the other side of the step, making it easy to install and handling High nature. In addition, since the light emitting / receiving element and the light emitting / receiving element control element are separately sealed by the first sealing resin and the second sealing resin, respectively, the connection between the light emitting / receiving element control element and the electrical wiring thereof is performed. For example, a light-transmitting transparent resin that melts the light emitting / receiving element and the optical path conversion mirror of the optical waveguide at a relatively low temperature, for example, is sealed with a second sealing resin such as a transfer mold resin that melts at a relatively high temperature. By sealing with a first sealing resin such as the above, resin sealing is possible even in an optical substrate on which an optical waveguide is mounted.

Moreover , since a metal film is provided on the back surface of the light input / output part of the optical path conversion mirror, the light incident on the optical path conversion mirror can be reliably reflected in the required direction, and the first sealing resin can be directly applied to the optical waveguide. by the optical path conversion mirror without contacting Ru can indirectly seal protects the optical waveguide together with the optical element. And the reliability with respect to the environmental change of an optical path conversion mirror part can be improved by forming a metal film in an optical path conversion mirror.

In addition, a convex portion may be provided on the substrate and an optical waveguide may be provided on the convex portion, and the light emitting / receiving element provided on the substrate and the optical waveguide may be joined.
By forming a convex portion having a height equivalent to the height of the light emitting / receiving element provided on the substrate as a step, when the optical waveguide is installed on the convex portion, the light emitting / receiving element having the light input / output portion of the optical waveguide installed on the substrate It can be easily and easily coupled to the light emitting / receiving surface.

Moreover, the same material as the electrical wiring provided in the front and back of the board | substrate may be sufficient as a convex part.
In this case, when patterning the electrical wiring on the metal base layer provided on the front and back of the substrate, the convex portion is made of the same material as the electrical wiring. The optical waveguide can be easily formed, the installation portion of the optical waveguide can be flattened, and the mounting accuracy and mounting reliability of the optical waveguide are improved.
Alternatively, the convex portion may be a spacer, for example, a resin-made or metal-made spacer having a predetermined thickness is prepared in advance and placed on the substrate, so that the optical waveguide and the light emitting / receiving element installed on the convex portion A necessary step can be formed between the two.

Further, a groove portion may be formed in the substrate, a light emitting / receiving element may be installed in the groove portion, and the light input / output portion of the optical waveguide installed in the substrate may be bonded to the light emitting / receiving element.
By setting the depth of the groove to a length corresponding to the height of the light receiving / emitting element, the light input / output part of the optical waveguide installed on the substrate and the light receiving / emitting surface of the light receiving / emitting element can be optically connected.

In the method of manufacturing an optical substrate according to the present invention, electrical wiring of a substrate patterned on the front and back sides of an insulating resin is connected by a via hole, and a light emitting / receiving element control element mounted on the electrical wiring is connected to the electrical wiring. In the method of manufacturing an optical substrate in which the connection portion between the light emitting / receiving element control element and the electrical wiring is sealed with a second sealing resin, an optical waveguide having an optical path conversion mirror on the end surface, A step of providing a step with respect to the light receiving / emitting surface so that the light input / output unit is connected to the light receiving / emitting surface of the light emitting / receiving element, and a connection portion between the light receiving / emitting element and the electric wiring at the end face of the optical waveguide And a step of sealing with a first sealing resin having a melting temperature lower than that of the second sealing resin together with an optical path conversion mirror having a metal film formed on the back surface of the light input / output unit. To do.
According to the present invention, when the optical waveguide is optically connected to the light emitting / receiving element, the optical waveguide is disposed on the substrate with a step difference from the light emitting / receiving element, so that the optical waveguide is disposed at a relative step portion of the substrate. When installed on one surface, the light input / output unit can be optically opposed to the light emitting / receiving surface of the light emitting / receiving element installed on the other surface of the step to perform bonding. The light emitting / receiving element and the light emitting / receiving element control element are separately sealed with the first sealing resin and the second sealing resin, respectively, and at that time, a connection portion between the light emitting / receiving element control element and the electric wiring Is sealed with a second sealing resin such as transfer mold resin that melts at a relatively high temperature, and the connection portion between the light emitting / receiving element and the electrical wiring and the optical path conversion mirror of the optical waveguide are melted at a relatively low temperature, for example. By sealing with a first sealing resin such as a light-transmitting transparent resin, the resin can be sealed even in an optical substrate on which an optical waveguide is mounted. In addition, the optical waveguide is not directly sealed by the first sealing resin by the optical path conversion mirror, or even if sealed, the end face is not sealed by the resin, so that it is not damaged by the heat of the resin in a molten state. .
The light incident on the optical path conversion mirror can be reliably reflected in the required direction, and the first sealing resin can be indirectly integrated with the light emitting / receiving element by the optical path conversion mirror without directly contacting the optical waveguide. Sealing protection is possible. In addition, by forming a metal film on the back surface of the optical path conversion mirror, the reliability of the optical path conversion mirror portion with respect to environmental changes can be improved.
In the present invention, the step of sealing the connection portion between the light emitting / receiving element control element and the electric wiring with the second sealing resin is performed in such a manner that the light input / output portion of the optical waveguide is optically coupled to the light emitting / receiving surface of the light emitting / receiving element. You may process before the process connected to this, and may process after. In addition, by sealing the light emitting / receiving element and the optical path conversion mirror of the optical waveguide with a first sealing resin that melts at a relatively low temperature, it is possible to prevent the optical waveguide from being damaged by heat and perform resin sealing. It is.

Also, by providing a convex part made of the same material as the spacer or electrical wiring on the substrate and installing an optical waveguide on the convex part, the light receiving / emitting surface of the light emitting / receiving element and the optical input / output part of the optical waveguide are matched You may make it connect optically.
By providing a base material of the same material as the spacer or electrical wiring on the substrate as a convex portion, a step can be formed between the optical waveguide provided on the convex portion and the light emitting and receiving element provided on the substrate. The light emitting / receiving surface can be easily connected.

Also, a groove portion is formed in the substrate, the light emitting / receiving element is installed, an optical waveguide is installed in the substrate, and the light receiving / emitting surface of the light receiving / emitting element and the light input / output portion of the optical waveguide are aligned to be optically connected. It may be.
By providing the light emitting / receiving element in the groove portion of the substrate, the light input / output portion of the optical waveguide provided on the substrate can be optically connected with the light receiving / emitting surface of the light receiving / emitting element.

According to the optical substrate and the method for manufacturing the same according to the present invention, the optical waveguide can be optically connected to the light emitting / receiving element by providing a step between the light emitting / receiving element and the optical waveguide installed on the substrate. Waveguides can be optically installed to improve handling. In addition, the light emitting / receiving element, the optical waveguide, and the light receiving / emitting element control element can be separately sealed with the first sealing resin and the second sealing resin, respectively, and the optical waveguide is passed through the optical path conversion mirror. The first sealing resin that melts at a lower temperature than the two sealing resins can be sealed together with the electrical wiring of the light emitting / receiving element, and the optical waveguide can be prevented from being damaged by heat.
In addition, the light incident on the optical path conversion mirror can be reliably reflected in the required direction, and the first sealing resin can be indirectly integrated with the light receiving and emitting element by the optical path conversion mirror without directly contacting the optical waveguide. Sealing protection is possible. And the reliability with respect to the environmental change of an optical path conversion mirror part can be improved by forming a metal film in an optical path conversion mirror.

It is explanatory drawing which shows the cross-sectional structure of the optical board | substrate by 1st embodiment of this invention. It is an enlarged view of the junction part of the optical waveguide and light emitting / receiving element in the optical substrate shown in FIG. (A)-(e) is explanatory drawing which shows the manufacturing method of the optical board | substrate by 1st embodiment. (F)-(h) is explanatory drawing which shows the manufacturing method of the optical board following FIG. (I)-(k) is explanatory drawing which shows the manufacturing method of the optical board following FIG. It is explanatory drawing which shows the cross-sectional structure of the optical board | substrate by 2nd embodiment of this invention. (M)-(p) is explanatory drawing which shows the manufacturing method of the optical board | substrate by 2nd embodiment. (Q)-(t) is explanatory drawing which shows the manufacturing method of the optical board following FIG.

Next, the optical substrate and the manufacturing method thereof according to the embodiment of the present invention will be described in detail.
In the optical substrate 1 according to the first embodiment shown in FIG. 1, conductive layers 3 and 4 as electric wirings made of a metal foil such as copper are provided on the front surface 2a and the back surface 2b of the substrate 2 made of a sheet-like insulating resin layer. Is formed by patterning, for example. A plurality of via hole holes 5 extending in the thickness direction and penetrating the front and back surfaces 2a and 2b are formed in the substrate 2, and via holes 6 are provided in the holes 5 by, for example, copper plating. The electrical wirings 3 and 4 on the front and back surfaces 2a and 2b are in a conductive state by the via hole 6.
A light emitting / receiving element control element 8 is mounted on one end of the via hole 6, for example, an electrode made of the conductive layer 3 exposed on the surface 2a by, for example, flip chip mounting. A terminal (not shown) of the light emitting / receiving element control element 8 is electrically connected to another via hole 6 by, for example, wire bonding 9. A configuration in which the light emitting / receiving element control element 8 is connected to the electrode (electrical wiring) of the conductive layer 3 in the via hole 6 through wire bonding is referred to as a connection portion.

In the substrate 2, for example, a groove 11 is formed at a position separated from the light emitting / receiving element control element 8 on the surface 2 a. A light emitting / receiving element 12 is mounted in the groove 11 and is fixed by an adhesive 13 applied in the groove 11. The depth of the groove 11 is substantially the same as the height of the light emitting / receiving element 12 fixed inside, and the light receiving / emitting surface 12a is exposed on the surface 2a of the substrate 2 substantially flush.
Wire bonding, solder connection, or the like is used for connection between a terminal (not shown) provided on the light emitting / receiving surface 12a of the light emitting / receiving element 12 and an electric wiring formed by the patterned conductive layer 3 provided on the surface 2a of the substrate 2. In this embodiment, wire bonding 9 is provided. A configuration from the light emitting / receiving element 12 to the conductive layer 3 (electrical wiring) connected through the wire bonding 9 is referred to as a connection portion. The light emitting / receiving element 12 is controlled by the light emitting / receiving element control element 8.
An optical waveguide 15 is provided on the surface 2 a of the substrate 2 for transmitting and receiving optical signals at high speed and inputting and outputting optical signals to and from the light receiving and emitting elements 12. As shown in FIG. 2, the end face 15a of the optical waveguide 15 is formed in an inclined surface of, for example, approximately 45 °, and the optical path conversion mirror 16 is joined to the end face 15a. A metal film 17 is deposited on the surface opposite to the end surface 15a of the optical path conversion mirror 16 by vapor deposition or the like. In the optical waveguide 15, a light input / output surface 15 b is provided as a light input / output unit facing the end surface 15 a at an angle of 45 °, and the light input / output surface 15 b is optically aligned with the light receiving / emitting surface 12 a of the light receiving / emitting element 12. Are aligned and connected. The interface between the light emitting / receiving element 12 and the optical waveguide 15 is filled with an optical adhesive.

An optical signal traveling through the optical wiring in the optical waveguide 15 is converted by the optical path conversion mirror 16 at the end face 15a to a 90 ° optical path, emitted from the input / output face 15b, and incident on the light receiving / emitting element 12 from the light receiving / emitting face 12a. An optical signal is scanned from the light emitting / receiving surface 12 a of the light emitting / receiving element 12 into the optical waveguide 15.
Here, as the optical waveguide 15, for example, an optical waveguide in which general optical wiring is formed on an optical waveguide film can be used. As a transmission mode of the optical wiring, it is possible to adopt a configuration such as a single mode, a multimode, and a single multi mixed wiring.
The light emitting / receiving element 12 may be a single channel or a plurality of channels of optical elements. Specifically, an edge-emitting LD, a surface-emitting LD, a surface-receiving PD, or the like can be used.

In FIG. 1, the first sealing resin extends from the optical path conversion mirror 16 to the region of the conductive layer 3 electrically connected by the wire bonding 9 on the light emitting / receiving surface 12 a of the light emitting / receiving element 12 and the surface 2 a of the substrate 2. 18 is sealed.
As the first sealing resin 18, for example, a liquid transparent resin can be filled by potting. As the transparent resin, generally used polymer materials can be used. Specifically, a carbonate material, an epoxy material, an acrylic material, an imide material, a urethane material, a silicone material, an organic material mixed with an inorganic filler, and the like can be used. However, the material is not limited thereto. Further, in order to eliminate the difference in refractive index at the interface, it is desirable to use an optical resin having a refractive index equivalent to that of the optical waveguide.
By potting and sealing the light emitting / receiving element 12 using, for example, a light transmissive transparent resin with a dispenser, the end surface 12a of the optical waveguide 15 can also be sealed with the resin via the optical path conversion mirror 16.
In addition, the second sealing resin 19 seals up to the electrode of the via hole 6 electrically connected to the light emitting / receiving element control element 8 and the wire bonding 9. A transfer mold resin can be used as the second sealing resin 19.
Here, the first sealing resin 18 is preferably made of a material having a melting temperature lower than that of the second sealing resin 19. Thereby, the optical waveguide 15 can be protected without being damaged by the heat of the molten resin when the first sealing resin 18 is filled. In this case, the first sealing resin 18 may cover the optical waveguide 15 except the end face 15a.

The optical substrate 1 according to the present embodiment has the above-described configuration, and a manufacturing method thereof will be described with reference to FIGS.
First, as shown in FIG. 3A, a substrate 2 made of an insulating resin layer having conductive metal foils 3a and 3a attached to the front and back surfaces 2a and 2b is used. Arbitrary organic materials and inorganic materials can be used for the insulating resin layer of the substrate 2. Specifically, an acrylic material, a silicone material, a silicon wafer, a metal material, a glass material, a prepreg, a laminated plate material, or the like can be used, but is not limited thereto. The metal foil 3a may be anything as long as it is made of metal, but copper is generally preferable from the viewpoint of cost and conductivity, and copper foil having good smoothness such as electrolytic copper foil and rolled copper foil is more preferable.

Next, via holes 5 are opened in the substrate 2 (see FIG. 3B), and via holes 6 are formed by plating (see FIG. 3C). Laser processing is preferable as a method of forming the via hole 5. Lasers include carbon dioxide laser, YAG laser (fundamental wave, second harmonic, third harmonic, or fourth harmonic) or excimer laser. However, both of them are used for processing together with the metal foil 3a and the insulating resin layer. A YAG laser (third harmonic or fourth harmonic) or excimer laser that is a short wavelength laser of 400 nm or less that can be processed simultaneously is more preferable.
And the board | substrate 2 is immersed in liquids, such as potassium permanganate and sodium hydroxide liquid mixture, and the residue of the organic insulating material in the hole 5 for via holes is removed by a desmear process.
The plating process for forming the via hole 6 in the via hole 5 includes an electroless copper plating or direct plating process for forming an electroplating seed layer on the resin surface of the substrate 2, and a seed layer as a power supply pattern. There is an electrolytic plating process for performing plating.

Subsequently, by patterning and etching the metal foil 3a, the conductive layer 3 patterned on the electric wiring and the mounting pad is formed (see FIGS. 3D and 3E). Thereafter, Ni / Au plating and solder resist printing are also performed as necessary.
Then, the light emitting / receiving element control element 8 is mounted on the mounting pad made of the conductive layer 3 formed by the pattern of the metal foil 3a. The light emitting / receiving element control element 8 can be mounted by die bonding, wire bonding, flip chip mounting, or the like.
Further, after mounting the light emitting / receiving element control element 8, it is connected to the conductive layer 3 forming an electrode of another via hole 6 by wire bonding 9 (see FIG. 4F). A second sealing resin 19 is formed by sealing the light emitting / receiving element control element 8 including the periphery of the connection portion by the wire bonding 9 with a transfer mold resin (see FIG. 4G).

In another area of the substrate 2, the groove 11 is formed in the substrate 2 by a router or the like (see FIG. 4H). Then, the light emitting / receiving element 8 is embedded and fixed in the substrate 2 made of an insulating resin layer with an adhesive 13 (see FIG. 5I). The light emitting / receiving element 12 electrically connects the terminal of the light receiving / emitting surface 12a to the conductive layer 3 by wire bonding 9 or solder connection (see FIG. 5J).
Next, the optical waveguide 15 is placed on the front surface 2a of the substrate 2, and the light input / output surface 15b of the light input / output portion in which the optical path conversion mirror 16 is fixed to the end surface 15a is aligned with the light receiving / emitting surface 12a of the light receiving / emitting element 12 to Match and join (see FIG. 5 (k)). The interface between the light emitting / receiving element 12 and the optical waveguide 15 is filled with a transparent optical adhesive.
As the optical waveguide 15, an optical waveguide in which a general optical wiring is formed on an optical waveguide film is used. As a film material of the optical waveguide film, a polymer material such as carbonate, epoxy, acrylic, imide, urethane, norbornene, and an inorganic material such as quartz can be used. As a transmission mode of the optical wiring, it is possible to adopt a configuration such as a single mode, a multimode, and a single multi mixed wiring.
The light emitting / receiving element 12 is a single-channel or multi-channel optical element. Specifically, an edge-emitting LD, a surface-emitting LD, a surface-receiving PD, or the like is used.

Then, the connection portion between the light emitting / receiving element 12 and the conductive layer 3 and the region of the optical path conversion mirror 16 of the optical waveguide 15 are sealed with the first sealing resin 18 without using a mold. In the sealing process, potting sealing is performed using a light-transmitting liquid transparent resin as the first sealing resin 18 by a dispenser.
As the transparent resin, a generally used polymer material is used, and specifically, carbonate materials, epoxy materials, acrylic materials, imide materials, urethane materials, silicone materials, organic materials mixed with inorganic fillers, etc. can be used. It is not limited to this. Further, in order to eliminate the difference in refractive index at the interface, a liquid optical resin having a refractive index equivalent to that of the optical waveguide 15 is used as the transparent resin.
Moreover, the environmental reliability of the board | substrate 2 and mounted components can be improved by molding the arbitrary parts on the board | substrate 2 with mold resin.

According to the above-described optical substrate 1 according to the present embodiment, the groove 11 having a depth equivalent to the height of the light emitting / receiving element 12 is formed in the substrate 2 of the insulating resin layer, so that the optical waveguide 15 is formed on the surface 2a of the substrate 2. The optical connection between the light input / output surface 15b and the light emitting / receiving surface 12a can be made precisely and easily without adjusting the height when the layers are stacked, and handling is improved. And it becomes possible to manufacture the optical board | substrate 1 with sufficient productivity.
In addition, the first sealing resin 18 is used to mold and seal the joint portion between the light emitting / receiving surface 12a of the light emitting / receiving element 12 and the end surface 15a of the optical waveguide 15 and the connection portion of the light emitting / receiving surface 12a and the conductive portion 3 by the wire bonding 9. In addition, since the connection portion by wire bonding 9 between the light emitting / receiving element control element 8 and the conductive layer 3 of the electrode in the via hole 6 is separately molded and sealed by the second sealing resin 19, one of the sealing resin 18 second low resin melting temperature than the sealing resin 19, it can be used, for example a transparent resin, the light emitting and receiving element 12 and the optical with the optical waveguide 15 can be prevented from being damaged by heat The connection portion of the waveguide 15 can be reliably sealed and protected.
In particular, the periphery of the optical path conversion mirror 16 formed on the end surface 15a of the optical waveguide 15 is sealed with the first sealing resin together with the light emitting / receiving surface 12a of the light emitting / receiving element 12, thereby including the optical waveguide 15 having low heat resistance. Can be sealed with resin. In this case, by forming the metal film 17 or the like on the optical path conversion mirror 16, the optical waveguide 15 and its end surface 15a can be reliably protected and sealed with resin, and the environment can be changed.

Next, another embodiment of the present invention will be described. However, the same components as those of the above-described embodiment will be denoted by the same reference numerals, and description thereof will be omitted.
The optical substrate 21 according to the second embodiment will be described with reference to FIG.
The optical substrate 21 according to the second embodiment is different in the connection portion between the optical substrate 1 and the optical waveguide 15 according to the first embodiment described above, and is identical in other configurations. In the optical substrate 21 according to the second embodiment, the groove portion 11 is not provided in the substrate 2, and a metal foil 2a is used for the surface 2a, or a metal having a predetermined thickness made of the same material as the copper foil 2a by electrolytic plating. A layer (base material) is formed. And the convex part 22 for installing the optical waveguide 15 is formed by predetermined thickness by masking the part of the convex part 22, and etching another area | region. The height of the convex portion 22 is set to be approximately the same as the height of the light emitting / receiving element 12.
The light emitting / receiving element 12 is installed on the surface 2a of the substrate 2 adjacent to the convex portion 22, and the adhesive 13 is applied between the lower surface of the light emitting / receiving element 12 and the surface 2a of the substrate 2, thereby receiving and emitting the light emitting element. 12 is fixed on the substrate 2. The terminals of the light emitting / receiving surface 12 a of the light emitting / receiving element 12 and the conductive layer 3 are electrically connected by, for example, wire bonding 9.

And the optical waveguide 15 is installed in the convex part 22, The light entrance / exit surface 15a is contact | abutted to the light emitting / receiving surface 12a of the light emitting / receiving element 12, and is optically connected. The interface between the light emitting / receiving element 12 and the optical waveguide 15 is filled with an optical adhesive and fixed. The optical waveguide 15 is not limited to the optical waveguide film, and a thin optical fiber array can be used as the optical waveguide 15.
In this state, the region between the light receiving / emitting surface 12a of the light emitting / receiving element 12 and the connection portion by wire bonding 9 to the conductive layer 3 and the optical path conversion mirror 16 fixed to the end surface 12a of the optical waveguide 15 is the liquid transparent resin described above. The first sealing resin 18 is used for sealing. The first sealing resin 18 may be potted with mold resin, and the height thereof may be the same as that of the optical waveguide 15 installed on the convex portion 22.
Therefore, the optical substrate 21 according to the second embodiment can obtain the same effects as the optical substrate 1 according to the first embodiment.

In the optical substrate 21 according to the second embodiment, a spacer having the same height may be installed on the substrate 2 instead of the convex portion 22 and fixed with an adhesive or the like. In this case, polyimide having high heat resistance is suitable as a material for the spacer, but other resin, metal, or the like may be used. In the case of manufacturing a spacer, polyimide or the like is spin-coated on a wafer and then cured, and this is peeled off to form a film, whereby a highly accurate spacer can be obtained.
And the produced spacer is adhere | attached on the board | substrate 2 with an adhesive agent.

Examples of the present invention will be described below. Moreover, although the following description demonstrates the optical waveguide 15 of the optical board | substrate 1 as a single layer optical waveguide film, it does not necessarily need to be 1 layer. Moreover, although the following description demonstrates the optical waveguide 15 as multimode, it does not necessarily need to be multimode.
(Example 1)
As Example 1, first, as a base material 2, a Toray-made product using a polyimide base material with copper foil 3 a on both sides (copper foil 12 μm thickness, polyimide 100 μm thickness, see FIG. 3A) as an insulating resin layer is used. . A plurality of via-holes 5 were formed by processing the front and back surfaces 2a and 2b with an ultraviolet laser (YAG third harmonic) having a wavelength of 355 nm (see FIG. 3B). The inner diameter of the processed via hole 5 was 60 μm.

Subsequently, in order to remove the resin residue deposited in the via-hole 5, potassium permanganate and sodium hydroxide were dissolved in ion exchange water at a ratio of 3 to 2 and heated to about 50 ° C. The substrate 2 was immersed in this mixed solution, and the resin residue was removed.
Next, the via hole 5 was subjected to copper plating to form a via hole 6 (see FIG. 3C). In order to form a wiring pattern on the front and back surfaces 2a and 2b of the substrate 2, a dry film resist for forming a wiring was pressed and bonded while being heated by a laminator to form a resist layer. Furthermore, it exposed with the parallel light which used the ultrahigh pressure mercury lamp as the light source using the photomask in which the predetermined pattern was formed, and developed with 1% sodium carbonate aqueous solution, and obtained the desired etching resist pattern (FIG. 3). (See (d)).

The copper foil 3a was etched by etching with an aqueous ferric chloride solution having a specific gravity of 1.40. Thereafter, the resist was stripped with a 3% aqueous sodium hydroxide solution to obtain a circuit pattern (electric wiring) as the conductive layer 3 (see FIG. 3E).
Next, a “VCSEL driver chip” 350 μm thick (manufactured by HELIX AG) is mounted on the electrode of the conductive layer 3 made of the patterned copper foil 3 a as the light emitting / receiving element control element 8. Electrical connection was made (see FIG. 4 (f)).
Next, the periphery including the light emitting / receiving element control element 8 and the wire bonding 9 was covered with a transfer mold resin as the second sealing resin 19 (see FIG. 4G).

Next, the substrate 2 was subjected to router processing to form a groove 11 (see FIG. 4H). A “4cH VCSEL” 150 μm thick (manufactured by ULM) was mounted as the light emitting / receiving element 12 in the groove 11 and fixed by the adhesive 13 (see FIG. 5I).
Next, the light emitting / receiving element 12 and the patterned copper foil conductive layer 3 were connected by wire bonding 9 (see FIG. 5J).
Then, a multi-mode epoxy optical waveguide film (manufactured by NTT-AT) is installed as the optical waveguide 15 on the insulating resin layer substrate 2 (see FIG. 5 (k)), and an epoxy-based refractive index matching optical adhesive (NTT-AT). To the surface 2 a of the substrate 2.

Next, a liquid transparent resin made of an epoxy-based refractive index matching optical adhesive (manufactured by NTT-AT) is used as a connecting portion between the light input / output surface 15b of the optical waveguide 15 and the light receiving / emitting surface 12a of the light receiving / emitting element 12. One sealing resin 18 was coated. Thereby, the optical substrate 1 was manufactured (see FIG. 1) .
As a result of evaluating the optical characteristics of the optical substrate 1, a stable light output of 0.8 to 1.1 mW was confirmed in each channel.

(Example 2)
Next, a method for manufacturing the optical substrate 21 according to the second embodiment will be described as Example 2. In the second embodiment, the optical substrate 21 is manufactured by the same method as in the first embodiment until the step of forming the second sealing resin 19 on the substrate 2 by transfer molding sealing the light emitting / receiving element control element 8 and the peripheral portion. Therefore, it is omitted.
Below, the process in the case of producing the convex part 22 by patterning fundamentally is demonstrated.

In Example 2, via holes 6 were formed in the substrate 2 of the insulating resin layer provided with the copper foils 3a on both front and back surfaces in the same manner as in Example 1 (see FIGS. 3A to 3E).
Next, the surface on which the convex portion 22 was to be formed was covered with a film mask 24 (FIG. 7 (m)), and chemical polishing was performed to make the thickness portion of the copper foil 3a excluding the film mask 24 portion into a thin layer. (See FIG. 7 (n)). The thickness of the copper foil 3a was 180 μm at the film mask portion, and the thickness of the other portions was reduced from 180 μm to 15 μm. The chemical polishing liquid used was a sulfuric acid / hydrogen peroxide type chemical polishing liquid.
Thereafter, similarly, an etching resist pattern was formed (see FIG. 7 (n)) to form a circuit pattern made of the conductive layer 3, that is, an electric wiring, and the film mask 24 was removed. Thereby, the convex part 22 was formed in the surface 2a of the board | substrate 2 (refer FIG.7 (o), (p)).

Next, the light emitting / receiving element control element 8 was mounted on the electrode of the conductive layer 3 patterned in the via hole 6, and electrical connection with the other conductive layer 3 was performed by wire bonding 9 (see FIG. 8 (q)). ). Then, the peripheral region including the light emitting / receiving element control element 8 and the wire bonding 9 was covered with the transfer molding resin as the second sealing resin 19 (see FIG. 8 (r)).
Next, on the surface 2 a of the substrate 2, the light emitting / receiving element 12 was mounted at a position adjacent to the convex portion 22, and the bottom surface was bonded and fixed with the adhesive 13. Then, the light emitting / receiving element 12 was connected to the conductive layer 3 of the electric wiring made of the patterned copper foil by wire bonding 9 (see FIG. 8 (s)).

Next, the optical waveguide 15 was installed on the convex part 22 (refer FIG.8 (t)). An epoxy type refractive index matching optical adhesive (manufactured by NTT-AT) was used for installation and fixing of the optical waveguide 15. Then, the connecting portion between the optical waveguide 15 and the light emitting / receiving element 12 was covered with a transparent resin made of an epoxy-based refractive index matching optical adhesive as the first sealing resin 18 to manufacture the optical substrate 21 shown in FIG.
As a result of evaluating the optical characteristics of the optical substrate 21, a stable light output of 0.8 to 1.1 mW was confirmed in each channel.

  In addition, when producing the convex part 22, it may replace with the method of producing copper foil by the patterning by the film mask 24, and may produce it with the spacer made from a synthetic resin. In this case, in FIG. 7 (m), the copper foil deposited on the surface 2a of the substrate 2 is not provided with the film mask 24, and FIGS. In the same manner as shown in FIG. 5, after forming a circuit pattern (electrical wiring) by an etching resist pattern, a spacer may be laminated and fixed to the surface 2a of the substrate 2 with an adhesive.

1,21 Optical substrate
2 Insulating resin layer substrate 2a Surface 3 Conductive layer 5 Via hole 6 Via hole 8 Light emitting / receiving element control element 9 Wire bonding 11 Groove 12 Light emitting / receiving element 13 Adhesive 15 Optical waveguide 16 Optical path conversion mirror 17 Metal film 18 First sealing Stop resin 19 Second sealing resin 22 Convex part 24 Film mask

Claims (8)

A substrate made of an insulating resin layer with electrical wiring patterned on the front and back;
Via holes connecting the electrical wiring on the front and back of the substrate;
A light emitting / receiving element provided on the substrate;
A light emitting and receiving element control element mounted on the electrical wiring;
An optical substrate installed on the substrate and having an optical waveguide provided with an optical path conversion mirror on an end face,
The light emitting / receiving element and the optical waveguide are disposed on the substrate with a step and are joined so as to be optically connected via the optical path conversion mirror,
The connection portion between the light emitting / receiving element and the electric wiring and the optical path conversion mirror of the optical waveguide are covered with a first sealing resin, and the connection portion between the light emitting / receiving element control element and the electric wiring is the second. of is covered with the sealing resin, the first sealing resin the second melting temperature than the sealing resin is rather low, a metal film is provided on the back surface of the light input portion of the optical path conversion mirror light board, characterized in that there. Providing a convex portion on the substrate and the optical waveguide is installed on the convex portion,
The optical substrate according to claim 1, wherein the light emitting / receiving element provided on the substrate and the light input / output unit of the optical waveguide are joined. The optical substrate according to claim 2 , wherein the convex portion is made of the same material as the electrical wiring provided on the front and back surfaces of the substrate. The optical substrate according to claim 2 , wherein the convex portion is a spacer. A groove is formed in the substrate, and the light emitting / receiving element is installed in the groove,
The optical substrate according to claim 1 , wherein an optical input / output unit of the optical waveguide installed on the substrate and the light emitting / receiving element are joined. The electrical wiring of the substrate formed by patterning electrical wiring on the front and back of the insulating resin layer is connected by a via hole, and the light emitting / receiving element control element mounted on the electrical wiring is connected to the light emitting / receiving element connected to the electrical wiring. A method for producing an optical substrate, provided on a substrate, wherein a connection portion between the light emitting / receiving element control element and an electric wiring is sealed with a second sealing resin,
A step of providing an optical waveguide having an optical path conversion mirror on an end surface thereof on the substrate with a step with respect to the light emitting / receiving surface such that the light input / output unit is bonded to the light emitting / receiving surface of the light emitting / receiving element; ,
The melting point is lower than that of the second sealing resin together with the optical path conversion mirror in which the connection portion between the light emitting / receiving element and the electric wiring is provided on the end surface of the optical waveguide and the metal film is formed on the back surface of the light input / output portion. And a step of sealing with a first sealing resin. The substrate is provided with a convex portion made of the same material as the spacer or the electric wiring, and an optical waveguide is installed on the convex portion, so that the light emitting / receiving surface of the light emitting / receiving element provided on the substrate and the optical waveguide 7. The method of manufacturing an optical substrate according to claim 6 , wherein the optical input / output portions are matched and optically connected. Forming a groove in the substrate and installing the light emitting / receiving element in the groove;
7. The method of manufacturing an optical substrate according to claim 6 , wherein an optical waveguide is installed on the substrate, and the light receiving / emitting surface of the light emitting / receiving element and the light input / output portion of the optical waveguide are aligned and optically connected. .

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