JP2012008488A - Optical element mounting substrate, photoelectric hybrid substrate, and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical element mounting substrate capable of easily positioning in mounting an optical element, a photoelectric hybrid substrate which includes the optical element mounting substrate and has excellent light propagation capability and productivity, and an electronic apparatus having the optical element mounting substrate or the photoelectric hybrid substrate.SOLUTION: An optical element mounting substrate on which an optical element 3 having a light-receiving part/light-emitting part 4 is mounted is laminated on an optical circuit layer in which a light waveguide is formed. The optical element mounting substrate is formed by laminating an insulating substrate 1 on an electric circuit layer 2, and has at least one recess at a side of the electric circuit layer or the insulating substrate in a thickness direction. At least a part of the optical element is held in the recess.

Description

  The present invention relates to an optical element mounting substrate, an opto-electric hybrid substrate, and an electronic device.

In recent years, with the wave of computerization, wideband lines (broadband) capable of exchanging large amounts of information at high speed have been spreading. Also, as devices for transmitting information to these broadband lines, transmission devices such as router devices and WDM (Wavelength Division Multiplexing) devices are used. In these transmission apparatuses, a large number of signal processing boards in which arithmetic elements such as LSIs and storage elements such as memories are combined are installed, and each line is interconnected.
Each signal processing board has a circuit in which arithmetic elements, storage elements, etc. are connected by electrical wiring. However, with the increase in the amount of information to be processed in recent years, each board has a very high throughput. It is required to transmit. However, with the speeding up of information transmission, problems such as generation of crosstalk and high-frequency noise, deterioration of electric signals, and mismatch of characteristic impedance are becoming apparent. For this reason, electrical wiring becomes a bottleneck, making it difficult to improve the throughput of the signal processing board.

On the other hand, an optical communication technique for transferring data using an optical carrier wave has been developed, and in recent years, an optical waveguide is becoming popular as a means for guiding the optical carrier wave from one point to another point. This optical waveguide has a linear core part and a clad part provided so as to cover the periphery thereof. The core part is made of a material that is substantially transparent to the light of the optical carrier wave, and the cladding part is made of a material having a refractive index lower than that of the core part.
In such an optical waveguide, light introduced from one end of the core portion is conveyed to the other end while being reflected at the boundary with the cladding portion. A light emitting element such as a semiconductor laser is disposed on the incident side of the optical waveguide, and a light receiving element such as a photodiode is disposed on the emission side. Light incident from the light emitting element propagates through the optical waveguide, is received by the light receiving element, and performs communication based on the blinking pattern of the received light.

Recently, there has been a movement to replace electric wiring in a signal processing board with an optical waveguide. By replacing the electrical wiring with an optical waveguide, it is expected that the problem of the electrical wiring as described above will be solved and the signal processing board will be able to further increase the throughput.
Electrical wiring for supplying electric power is indispensable for driving each element such as a light emitting element and a light receiving element responsible for mutual conversion between an optical signal and an electric signal as well as an arithmetic element and a memory element. For this reason, electric wiring and an optical waveguide are mixedly mounted on the signal processing substrate, and development of such a substrate (photoelectric mixed substrate) is being promoted.

In an opto-electric hybrid board, alignment of the light emitting / receiving point of the light emitting / receiving element and the optical waveguide is required to be very highly accurate, and various attempts have been made.
For example, Patent Document 1 describes a method of aligning an optical waveguide substrate and a light emitting / receiving point via a vertical recognition camera. However, it is an invention that uses a plurality of light emitting points to increase the allowable range of positional deviation, and it is difficult to deal with a more precise waveguide structure. In addition, a large number of man-hours are required, such as preparing a plurality of light emitting points, measuring the light coupling efficiency of each light emitting point, and determining the light emitting point to be used.
On the other hand, Patent Document 2 describes a photoelectric composite substrate using optical through holes. This is a general optical coupling method, but when the substrate on which the optical through hole is formed is thick, there is a concern that the distance between the light receiving / emitting point and the optical waveguide becomes wide and the optical coupling loss increases.
Patent Document 3 describes that a step portion is provided in an insulating resin layer, the step portion is used as a bonding positioning guide, and the optical element mounting substrate and the optical waveguide are bonded. According to this method, alignment is easy, and optical connection between the optical element and the optical waveguide can be performed with high accuracy. However, when the optical waveguide is formed of a polymer material, a dimensional change occurs due to heating or the like in the manufacturing process of the optical waveguide, and it becomes difficult to join the step portion. When the core pattern of the optical waveguide is changed, the arrangement of the insulating resin layer and the optical element needs to be changed.

JP 2006-258863 A JP 2007-148087 A JP 2009-288636 A

  The present invention relates to an optical element mounting substrate that can be easily aligned at the time of mounting the optical element, the optical element mounting substrate that includes the optical element mounting substrate, and an optical / electrical mounting substrate that is excellent in light propagation performance and productivity, and an optical element mounting substrate or an optical / electrical mounting An electronic apparatus including a substrate is provided.

The present invention is an optical element mounting substrate on which an optical element that is stacked on an optical circuit layer in which an optical waveguide is formed and has a light receiving part or a light emitting part is mounted,
An electric circuit layer and an insulating substrate are laminated, and the optical element mounting substrate has at least one recess in the thickness direction on the electric circuit layer side or the insulating substrate side, and at least the optical element Part of the optical element mounting substrate is housed in the recess.
According to another aspect of the present invention, there is provided an opto-electric hybrid board, wherein the optical element mounting board is laminated on one surface of an optical circuit layer on which an optical waveguide is formed.
According to another aspect of the present invention, there is provided an electronic apparatus comprising the optical element mounting substrate.
According to another aspect of the present invention, there is provided an electronic apparatus including the opto-electric hybrid board.

  According to the present invention, it is easy to align when mounting an optical element on an optical element mounting substrate, and an optical element mounting substrate having a thin total thickness can be obtained. In addition, an opto-electric hybrid board that includes an optical element mounting substrate, in which coupling loss between the optical waveguide and the light receiving and emitting element is sufficiently suppressed, and an electronic device including the optical element mounting substrate or the opto-electric hybrid board are obtained. Can do.

It is sectional drawing which shows one Embodiment of the opto-electric hybrid board | substrate of this invention. It is sectional drawing which shows one Embodiment of the optical element mounting substrate of this invention. It is sectional drawing which shows one Embodiment of the optical element mounting substrate of this invention. It is sectional drawing which shows one Embodiment of the optical element mounting substrate of this invention. It is sectional drawing which shows one Embodiment of the optical element mounting substrate of this invention. It is sectional drawing which shows one Embodiment of the opto-electric hybrid board | substrate of this invention. It is sectional drawing which shows one Embodiment of an optical waveguide. It is a top view which shows one Embodiment of the optical element mounting substrate of this invention.

  Hereinafter, an optical element mounting substrate, an opto-electric hybrid board, and an electronic apparatus according to the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

(First embodiment)
<Optical / electrical hybrid substrate 100>
FIG. 1 is a cross-sectional view schematically showing an example of the opto-electric hybrid board 100 of the present embodiment. In the following description, the upper side in the figure is referred to as “upper” and the lower side is referred to as “lower”. In the sectional view, the thickness direction of each substrate is emphasized.
The opto-electric hybrid board of this embodiment is a laminate of the optical element mounting board 10 of this embodiment and the optical circuit layer 20 in which an optical waveguide is formed. The optical element 3 mounted on the optical element mounting substrate 10 has an electrode 5 and a light receiving part or light emitting part 4, the electrode 5 is electrically connected to the electric circuit layer 2, and the light receiving part or light emitting part 4 is optical. Optical communication with the waveguide 200 is performed. In the optical waveguide 200, the light 9 propagates through the core portion 210, but the traveling direction is changed by the optical path changing portion 213, and light is exchanged with the light receiving portion or the light emitting portion 4 of the optical element 3. In FIG. 1, light 9 indicates a traveling direction of the light 9 when the light receiving unit or the light emitting unit 4 functions as a light emitting unit.
The distance between the light receiving part or light emitting part 4 of the optical element 3 and the upper surface of the optical circuit layer 20 is preferably 1 μm to 50 μm. Thereby, optical communication between the optical element 3 mounted on the optical element mounting substrate 10 and the optical circuit layer 20 can be performed with high efficiency.
Next, the optical element mounting substrate 10 and the optical circuit layer 20 will be described.

<Optical element mounting substrate 10>
The optical element mounting substrate 10 of this embodiment is obtained by laminating an electric circuit layer 2 and an insulating substrate 1. Thereby, the electric circuit layer 2 can be directly laminated on the optical circuit layer 20, and light can be propagated efficiently.
The optical element mounting substrate 10 has at least one recess in the thickness direction on the electric circuit layer 2 side or the insulating substrate 1 side, and at least a part of the optical element 3 is accommodated in the recess. In FIG. 1, the example which has a recessed part in the insulated substrate 1 side is shown.

<Optical element 3>
The optical element 3 shown in FIG. 2 has a light receiving part or light emitting part 4 and an electrode 5 on its outer surface.
In the present embodiment, the optical element 3 has a rectangular parallelepiped shape, and a light receiving part or a light emitting part 4 is provided at the center of one surface thereof. Electrodes 5 are provided on the left and right sides of the light receiving unit or the light emitting unit 4, respectively.
The optical element 3 shown in FIG. 2 is housed in the recess with the surface on which the light receiving unit or light emitting unit 4 and the electrode 5 are provided facing the side on which the electric circuit layer 2 is provided. Thereby, since the electrode 5 is naturally positioned on the through hole 6, it is easy to determine the mounting position of the optical element 3, and the electrical connection is established.
The optical element 3 has a light receiving part or a light emitting part 4 on the surface on which the optical circuit layer 20 is laminated. When the optical element mounting substrate 10 and the optical circuit layer 20 are laminated, the optical circuit layer 20 And optical communication. The light receiving unit or the light emitting unit 4 may be a light receiving / emitting unit having both functions.

Examples of such an optical element 3 include a light emitting element such as a surface emitting laser (VCSEL) and a light emitting diode (LED), and a light receiving element such as a photodiode (PD, APD).
Moreover, as a constituent material of each electrode 5, aluminum, copper, gold | metal | money, silver, platinum etc. are mentioned, for example.

In FIG. 2, the upper surface of the optical element 3 is located higher than the region excluding the optical element mounting portion of the insulating substrate 1, and the optical element 3 has a shape in which the optical element 3 protrudes upward in the optical element mounting substrate 10. When the thickness of the optical element 3 is smaller than the total thickness of the insulating substrate 1 and the electric circuit layer 2, the upper surface of the optical element 3 may be the same height as the upper surface of the optical element mounting substrate 1. Further, the upper surface of the optical element 3 may be positioned lower than the upper surface of the insulating substrate 1, and in this case, the underfill 7 may be disposed on the upper surface of the optical element 3.
The thickness of the insulating substrate 1 and the electric circuit layer 2 in the recess is preferably 1 μm to 10 μm. Thereby, the reliability of electrical connection and optical communication in the opto-electric hybrid board 100 can be further improved while maintaining the mechanical strength of the optical element mounting board 10.

  FIG. 8 is a top view of the optical element mounting substrate 10 shown in FIG. In the top view, the area of the recess is preferably 1.1 to 3 times the area of the optical element 3. In addition, since the said recessed part accommodates the said optical element 3, it is necessary to make it the shape which can accommodate the optical element 3 to mount. Further, it is preferable that there is at least one gap between the wall surface of the optical element 3 and the inner wall surface of the recess. Thereby, the workability when mounting the optical element 3 on the optical element mounting substrate 10 is improved, and the underfill material 7 can be poured from the gap.

  Although not particularly limited, the shape of the recess is preferably a shape similar to the shape of the optical element 3 in a top view. Thereby, space can be saved and the mounting position of the optical element 3 can be easily determined.

The optical element 3 has an electrode 5 on its lower surface and is electrically connected to the electric circuit layer 2. A through hole 6 is formed in the insulating substrate 1 existing between the electrode 5 and the electric circuit layer 2 and is electrically connected through the through hole 6.
A number of processing methods such as an electroless copper plating method and a direct plating method have been put to practical use as a method for conducting the conduction treatment of the inner wall of the through hole after the through hole drilling, but is not particularly limited.
Examples of the conductive material used for the through hole include various solders, various brazing materials, various conductive pastes (inks), and the like.
Among these, as solder and brazing material, Sn—Pb lead solder, Sn—Ag—Cu, Sn—Zn—Bi, Sn—Cu, Sn—Ag—In—Bi, Sn— Examples include various lead-free solders based on Zn-Al, various low-temperature brazing materials defined in JIS, and the like.
Examples of the conductive paste (ink) include solder paste, Ag paste, Cu paste, Au paste, and inks thereof. These conductive pastes (inks) have conductivity even before being dried, but exhibit excellent conductivity when dried or baked.

  In the electric circuit layer 2, it is preferable that at least a part of the light receiving portion or the light emitting portion 4 of the optical element does not overlap the electric wiring in the electric circuit layer 2 in the stacking direction of the optical element mounting substrate 10. Thereby, optical connection with the optical circuit layer 20 laminated | stacked under the electric circuit layer 2 can be performed smoothly.

It is preferable that the gap between the recess and the optical element 3 mounted in the recess is filled with an underfill agent and cured. Thereby, the optical element 3 can be reliably held in the recess. For filling the underfill agent, the optical element may be mounted after filling the recess with the underfill agent, or the underfill agent may be filled after mounting the optical element. When mounting the optical element after filling the underfill, the gap between the recess and the optical element can be filled without a gap. Also, when filling the underfill agent after mounting the optical element, the gap between the recess and the optical element can be filled. Since the gap is very narrow, it is possible to fill the underfill agent without gaps due to capillary action.
The underfill agent is preferably selected from the group consisting of a resin having a transparency of 90% or more at the wavelength of light used by the optical element after curing. Here, the wavelength of light used by the optical element refers to the wavelength of light that is emitted or received from the optical element 3 of this embodiment and propagates through the optical circuit layer 20. When a distribution occurs in the wavelength of light used by the optical element, it is preferably selected from the group consisting of a resin having a transmittance of 90% or more at the wavelength of the strongest light used by the optical element. Moreover, the said permeability | transmittance shall measure the resin shape | molded by the thickness of 50 micrometers after hardening.
As a result, there is no air layer between the light receiving unit or the light emitting unit and the optical waveguide, and there is an effect that the reflection that occurs at the interface between the air layer and the insulating substrate is eliminated and light is efficiently propagated. Specific examples include epoxy resins, oxetane resins, acrylic resins, methacrylic resins, silicon resins, silicate resins, BCB resins, norbornene resins, and organic-inorganic hybrid resins.

The insulating substrate 1 is laminated on the electric circuit layer 2.
As the insulating substrate 1, a flexible substrate having high flexibility or a rigid substrate having high rigidity is used.
Among these, a specific example of the flexible substrate includes a flexible insulating substrate using a film of polyester, polyimide, polyamide or the like.
In addition, the average thickness of the flexible substrate is preferably about 5 μm to 200 μm, more preferably about 10 μm to 100 μm, from the viewpoint of flexibility and thinning of the optical element mounting substrate 10. A flexible substrate having such a thickness has sufficient flexibility and prevents unintentional deformation due to its own weight or the weight of various elements to be mounted.
On the other hand, as specific examples of rigid substrates, glass substrate copper-clad laminates such as glass cloth and epoxy copper-clad laminates, composite copper-clad laminates such as glass nonwoven fabric and epoxy copper-clad laminates, polyetherimide resin substrates, Examples thereof include heat-resistant / thermoplastic organic rigid substrates included in polyetherketone resin substrates, polysulfone-based resin substrates and the like, and ceramic rigid substrates included in alumina substrates, aluminum nitride substrates, silicon carbide substrates and the like.

The constituent material of the insulating substrate 1 is preferably transparent at the wavelength of light used by the optical element. Here, the wavelength of light used by the optical element refers to the wavelength of light that is emitted or received from the optical element 3 of this embodiment and propagates through the optical circuit layer 20. When distribution occurs in the wavelength of the light, the constituent material of the insulating substrate 1 is preferably transparent at the wavelength of the strongest light used by the optical element. Thereby, the light propagation between the light receiving unit or the light emitting unit 4 and the optical circuit layer 20 can be efficiently performed. Here, having transparency of 90% or more at a specific wavelength is defined as being transparent at that wavelength. Further, the transparency is measured in the thickness direction of the insulating substrate 1.
Such a constituent material of the insulating base material 1 varies depending on the wavelength of light propagating through the optical circuit layer 20, and examples thereof include polyimide, polyamide, polyamideimide, polyester, glass cloth epoxy substrate, and glass substrate. .

On the other hand, electrical wiring is formed on the electric circuit layer 2 by, for example, a method of linearly patterning a conductive layer once formed on the entire surface, a method of transferring a conductive layer previously patterned in a linear shape, or the like. This electrical wiring is for electrically connecting the light receiving unit or light emitting unit 4 of the optical element 3 to a power source and various ICs (not shown). Or send it out. The drive of the optical element 3 can be controlled by such electrical wiring.
The average thickness of the electric circuit layer (electric wiring) 2 is appropriately set according to the constituent material of the electric circuit layer 2, the electric resistance value required for the electric wiring, and the like, but is about 1 μm to 30 μm as an example. .
Moreover, although the width of the electric wiring 2 is appropriately set according to the constituent material of the electric circuit layer 2, the electric resistance value required for the electric circuit layer 2, and the like, it is preferably about 2 μm to 1000 μm as an example. More preferably, it is about 5 to 500 μm.
As a constituent material of the electric circuit layer 2, for example, aluminum (Al), copper (Cu), gold (Au), silver (Ag), platinum (Pt), nickel (Ni), tungsten (W), molybdenum (Mo) And various metal materials.

<Optical circuit layer 20>
Any conventionally used optical circuit layer may be used as the optical circuit layer used in the present invention. Below, the example is demonstrated.
The optical circuit layer 20 shown in FIG. 1 has an optical waveguide 200. If necessary, a support substrate or the like may be provided. The optical waveguide 200 includes an optical waveguide 200 in which a clad layer (lower clad layer) 220, a core layer 210, and a clad layer (upper clad layer) 230 are laminated in this order from below. FIG. 7 is a cross-sectional view of the optical waveguide 200 cut perpendicularly to the extending direction of the optical waveguide 200. As shown in FIG. 7, the core layer 210 is formed with a core portion 211 and a side clad portion 212 adjacent to the side surface of the core portion 211.

  In the optical waveguide 200, the light incident on one end of the core part 211 is totally reflected at the interface between the core part 211 and the clad part (the clad layers 220 and 230 and the side clad parts 212), It can be propagated to the end. Thereby, optical communication can be performed based on the blinking pattern of the light received at the emitting end.

In order to cause total reflection at the interface between the core part 211 and the cladding part, a difference in refractive index needs to exist at the interface. Although the refractive index of the core part 211 should just be larger than the refractive index of a clad part, the difference is not specifically limited, However, It is preferable that it is 0.5% or more, and it is more preferable that it is 0.8% or more. On the other hand, the upper limit value may not be set, but is preferably about 5.5%. If the difference in refractive index is less than the lower limit, the effect of transmitting light may be reduced, and even if the upper limit is exceeded, no further increase in light transmission efficiency can be expected.
The difference in refractive index is expressed by the following equation, where A is the refractive index of the core portion 211 and B is the refractive index of the cladding portion.
Refractive index difference (%) = | A / B-1 | × 100

In the configuration shown in FIG. 7, the cross-sectional shape of the core portion 211 is generally a square such as a square or a rectangle (rectangle), but is not particularly limited, and may be a perfect circle or an ellipse. It may be a polygon such as a circle, a diamond, a triangle, or a pentagon. Further, in plan view, it may be formed in a straight line, or may be curved or branched in the middle, and its shape is arbitrary.
The width and height of the core part 211 are not particularly limited, but are preferably about 1 μm to 200 μm, more preferably about 5 μm to 100 μm, and still more preferably about 20 μm to 70 μm.

The constituent material of the core layer 210 is not particularly limited as long as the above-described refractive index difference is generated. Specifically, acrylic resin, methacrylic resin, polycarbonate, polystyrene, epoxy resin, polyamide, polyimide, polybenzoic acid are used. In addition to various resin materials such as oxazole, polysilane, polysilazane, and cyclic olefin resins such as benzocyclobutene resin and norbornene resin, glass materials such as quartz glass and borosilicate glass can be used.
Of these, norbornene resins are particularly preferable. These norbornene-based polymers include, for example, ring-opening metathesis polymerization (ROMP), combination of ROMP and hydrogenation reaction, polymerization by radical or cation, polymerization using a cationic palladium polymerization initiator, and other polymerization initiators ( For example, it can be obtained by any known polymerization method such as polymerization using a polymerization initiator of nickel or another transition metal).

  In addition, as a constituent material of the core part 211 and the side clad part 212, when the material causing the difference in refractive index as described above is not used, the core part 211 and the side clad part 212 made of different constituent materials are used in combination. May be. From the viewpoint of suppressing light attenuation, it is also important that the adhesiveness (affinity) between the constituent material of the core portion 211 and the constituent material of the side cladding portion 212 is high.

On the other hand, each of the cladding layers 220 and 230 constitutes a cladding part located at the lower part and the upper part of the core layer 210, respectively. Each of the clad layers 220 and 230 constitutes a clad portion surrounding the outer periphery of the core portion 211 together with the side clad portion 212, whereby the optical waveguide 200 functions as a light guide.
The average thickness of the cladding layers 220 and 230 is preferably about 0.1 to 1.5 times the average thickness of the core layer 210 (the average height of each core portion 211). More preferably, the average thickness of the clad layers 220 and 230 is not particularly limited, but is usually preferably about 1 μm to 200 μm, respectively, and about 5 μm to 100 μm. More preferably, it is about 10 μm to 60 μm. Thereby, the function as a clad layer is suitably exhibited while preventing the optical circuit layer 20 from becoming unnecessarily large (thickened).
Further, as the constituent material of each of the cladding layers 220 and 230, for example, the same material as the constituent material of the core layer 210 described above can be used, but a norbornene polymer is particularly preferable.
Moreover, when selecting the constituent material of the core layer 210 and the constituent material of the cladding layers 220 and 230, the material may be selected in consideration of the difference in refractive index between the two. Specifically, the refractive index of the constituent material of the core layer 210 is sufficiently higher than the refractive index of the cladding layers 220 and 230 in order to surely totally reflect light at the boundary between the core layer 210 and the cladding layers 220 and 230. The material may be selected so as to be larger. Thereby, a sufficient refractive index difference is obtained in the thickness direction of the optical circuit layer 20, and leakage of light from the core portion 211 to the cladding layers 220 and 230 can be suppressed.
From the viewpoint of suppressing light attenuation, it is also important that the adhesiveness (affinity) between the constituent material of the core layer 210 and the constituent materials of the cladding layers 220 and 230 is high.

This embodiment has the following effects.
The optical element mounting substrate of the present embodiment is an optical element mounting substrate on which an optical element having a light receiving portion or a light emitting portion is mounted, and is insulated from the electric circuit layer. The optical element mounting substrate is formed by laminating a substrate, and the optical element mounting substrate has at least one recess in the thickness direction on the electric circuit layer side or the insulating substrate side, and has a light receiving portion or a light emitting portion. At least one part is housed in the recess.
Since at least a part of the optical element 3 is accommodated in the recess of the optical element mounting substrate 10, the thickness of the optical element mounting substrate 10 of the present embodiment can be reduced and space can be saved. The electronic equipment can be downsized. In the present embodiment, the optical element mounting substrate 10 in which the insulating substrate 1 is laminated on the upper surface of the electric circuit layer 2 shortens the distance between the electrode 5 of the optical element 3 and the electric circuit layer 2, so that the reliability of electric connection is improved. Improves. Further, when the optical element mounting substrate 10 is stacked on the upper surface of the optical circuit layer 20, the distance between the light receiving part or the light emitting part 4 of the optical element 3 and the optical waveguide 200 is shortened, so that the reliability of optical communication is also improved. improves.

In the optical element mounting substrate of the present embodiment, the thickness of the insulating substrate 1 and the electric circuit layer 2 in the recess may be 1 μm to 10 μm.
Thereby, the electrical connection of the opto-electric hybrid board 100 and the reliability of optical communication can be further improved while maintaining the mechanical strength of the optical element mounting board 10.

In the optical element mounting substrate of the present embodiment, at least a part of the light receiving portion or the light emitting portion of the optical element does not overlap with the electric wiring in the electric circuit layer in the stacking direction of the optical element mounting substrate. preferable.
Thus, light can be smoothly exchanged between the light receiving unit or light emitting unit 4 of the optical element 3 and the optical waveguide 200.

The optical element mounting substrate of this embodiment is preferably one in which the insulating substrate 1 is laminated on the electric circuit layer 2.
Thereby, when the optical element 3 is accommodated in the recess of the optical element mounting substrate 10, the distance between the electrode 5 of the optical element 3 and the electric circuit layer 2, the light receiving part or the light emitting part 4 of the optical element 3, and the optical waveguide 200. Therefore, the reliability of electrical connection and optical communication can be improved.

It is preferable that the optical element mounting substrate of the present embodiment is obtained by filling and curing an underfill agent in a gap between the concave portion and the optical element mounted in the concave portion.
Thereby, the optical element 3 can be reliably fixed in the said recessed part, and physical strength can be improved. Furthermore, since the positional deviation between the light receiving unit or light emitting unit 4 and the optical path changing unit 213 can be prevented, the light propagation loss in the optical path changing unit 213 can be suppressed. Further, since the underfill agent is filled, propagation light propagating between the concave portion and the optical element 3 mounted in the concave portion can be prevented from diffusing and reflecting, so that the reliability of optical communication is improved. Can be improved.

In the optical element mounting substrate of the present embodiment, the underfill agent is preferably selected from the group consisting of a resin having a transmittance of 90% or more at the wavelength of light used by the optical element after curing.
Since the underfill agent described above is substantially transparent, it does not hinder the propagation of light between the optical path changing unit 213 and the light receiving unit or the light emitting unit 4 in the optical waveguide 200. Further, by using a material having a refractive index close to that of the constituent material of the insulating substrate 1, reflection / diffusion of propagating light at the interface between the insulating substrate 1 and the underfill 7 can be suppressed, so that the reliability of optical communication is improved. I can do it.

In the optical element mounting substrate of the present embodiment, the constituent material of the insulating substrate 1 is preferably transparent at the wavelength of light used by the optical element. Here, the term “transparent” means having a transmittance of 90% or more at the wavelength of light used by the optical element.
Thereby, light can be easily propagated between the light receiving part or the light emitting part 4 of the optical element 3 and the optical path changing part 213 in the optical waveguide 200 in the concave portion. Moreover, even if the insulating substrate 1 is thinned in the recess, an optical element mounting substrate with high mechanical strength can be obtained.
The constituent material of the insulating substrate is preferably selected from the group consisting of polyimide, polyamide, polyamideimide, polyester, glass cloth epoxy substrate, and glass substrate.
By using these materials, light propagation loss can be further suppressed.

As for the optical element mounting substrate of this embodiment, it is preferable that the area of the said recessed part is 1.1-3 times with respect to the area of the said optical element in the top view.
Thereby, it is easy to determine the mounting position where the optical communication between the optical element 3 and the optical waveguide 200 can be ensured, and the optical element 3 can be easily stored in the recess. Workability at the time of mounting becomes high.

In the optical element mounting substrate of the present embodiment, it is preferable that the optical element 3 and the electric circuit layer 2 are electrically connected through a through hole 6 formed in the insulating substrate 1.
Thereby, the electrical connection between the electric circuit layer 2 and the optical element 3 can be ensured. As shown in FIG. 2, when the through hole 6 is formed on the bottom surface of the concave portion, the through hole can be easily formed because the insulating substrate 1 is thinner than other portions.

(Second Embodiment)
Hereinafter, the optical element mounting substrate 10 according to the present embodiment shown in FIG. 3 will be described. The description will focus on the differences from the above-described embodiment, and the description of the same matters will be omitted. In FIG. 3, components similar to those in the above-described embodiment are denoted by the same reference numerals as those in FIG. 2 described above, and detailed description thereof is omitted.

The optical element mounting substrate 10 shown in FIG. 3 is the same as the embodiment shown in FIG. 2 except that the through hole 8 is provided in the recess of the insulating substrate 1.
In other words, in the present embodiment, it is a region in the concave portion of the insulating substrate 1 and connects at least a part of the light receiving part or the light emitting part 4 of the optical element 3 and at least a part of the optical path changing part 213 of the optical circuit layer 20. The region has a through-hole 8 that penetrates the concave portion of the insulating substrate 1.
In such a configuration, the interface between the light receiving unit or light emitting unit 4 of the optical element 3 and the optical path changing unit 213 of the optical circuit layer 20 is one less than in the above-described embodiment. For this reason, the loss by the spreading | diffusion and reflection of the propagation light etc. which arise in the interface of a different material can be suppressed further.

In the optical element mounting substrate of the present embodiment, the insulating substrate 1 preferably has a through hole that overlaps at least a part of the light receiving unit or the light emitting unit 4 in the stacking direction of the optical element mounting substrate.
Thereby, the reliability in the optical communication between the light receiving part or the light emitting part 4 of the optical element 3 and the optical circuit layer 20 can be improved.
In addition to the above-described operations and effects, the present embodiment can provide the same operations and effects as the above-described embodiments.

(Third embodiment)
Hereinafter, although the optical element mounting substrate 10 in this embodiment shown in FIG. 4 will be described, the difference from the above-described embodiment will be mainly described, and the description of the same matters will be omitted. In FIG. 4, components similar to those in the above-described embodiment are denoted by the same reference numerals as those in FIG. 2 described above, and detailed description thereof is omitted.

The optical element mounting substrate 10 shown in FIG. 4 may be a recess that penetrates the insulating substrate 1 and has the electric circuit layer 2 as a bottom surface. When the recess penetrates the insulating substrate 1, the optical element 3 is directly mounted on the electric circuit layer, and the electrode 5 and the electric circuit layer 2 are directly bonded. Examples of the method include ultrasonic welding and resistance welding.
In addition, the electrical circuit layer 2 and the electrode 5 of the optical element 3 can be sufficiently electrically connected even if they are simply in contact, but are connected via a conductive material or by direct bonding. Is preferred. Thereby, good electrical connection is maintained over a long period of time.
Examples of the conductive material include various solders, various brazing materials, various conductive pastes (inks), and the like.
Further, the solder and the brazing material are melted and fluidized by reflow, and spread around the contact portion between the electric circuit layer 2 and the electrode 5. Thereby, the electrical circuit layer 2 and the electrode 5 are connected in a wider area. As a result, the contact resistance is reduced, and stress that tends to concentrate on the connection portion can be relaxed to improve connection reliability.
When the conductive material is composed of solder (including a brazing material), there is a risk that a part of the metal component constituting the electric circuit layer 2 is dissolved on the solder side. This phenomenon is called “copper erosion” because it often occurs particularly with respect to copper wiring. If copper erosion occurs, there is a risk that the electrical wiring 2 becomes thin or breaks, and the function of the electrical circuit layer 2 may be impaired.
Therefore, it is preferable to form a copper erosion prevention film (underlayer) as a solder underlayer in advance on the surface of the electric circuit layer 2 in contact with the conductive material. By forming the copper erosion preventing film, copper erosion is prevented and the function of the electric circuit layer 2 can be maintained over a long period of time.
Examples of the constituent material of the copper corrosion prevention film include nickel (Ni), gold (Au), platinum (Pt), tin (Sn), palladium (Pd), and the like. A single layer composed of one kind of metal composition may be used, or a composite layer containing two or more kinds (for example, a Ni—Au composite layer, a Ni—Sn composite layer, etc.) may be used.
The average thickness of the copper erosion preventing film is not particularly limited, but is preferably about 0.05 to 5 μm, and more preferably about 0.1 to 3 μm. Thereby, it is possible to exhibit a sufficient copper erosion preventing action while suppressing the electrical resistance of the copper erosion preventing film itself.
In addition to the above-described operations and effects, the present embodiment can provide the same operations and effects as the above-described embodiments.

(Fourth embodiment)
Hereinafter, although the optical element mounting substrate 10 in this embodiment shown in FIG. 5 will be described, the difference from the above-described embodiment will be mainly described, and description of similar matters will be omitted. In FIG. 5, components similar to those in the above-described embodiment are denoted by the same reference numerals as those in FIG. 2 described above, and detailed description thereof is omitted.

The optical element mounting substrate 10 shown in FIG. 5 has the stacking direction of the electric circuit layer 2 and the insulating substrate 1 turned upside down and penetrates the electric circuit layer 2 to form a recess in the optical element mounting substrate 10. The optical element 3 has a light receiving portion or a light emitting portion 4 on the lower surface and an electrode 5 on the upper surface.
That is, in the embodiment shown in FIG. 2, the electrode 5 is disposed on the lower surface of the optical element 3 and is electrically connected to the electric circuit layer 2 through the through hole. The electrode 5 and the electric circuit layer 2 of the optical element 3 are disposed on the upper surface of the optical element 3, and the electrode 5 and the electric circuit layer 2 are electrically connected by wire bonding.
In such a configuration, since the electric circuit layer 2 does not exist between the optical path changing unit 213 of the optical circuit layer 20 to be laminated later with the optical element mounting substrate 10 and the light receiving unit or the light emitting unit 4 of the optical element 3, Since it does not hinder the transmission and reception of propagation light between the optical path changing unit 213 of the circuit layer 20 and the light receiving unit or the light emitting unit 4 of the optical element 3, it is possible to prevent a positional deviation when the optical element mounting substrate 10 and the optical circuit layer 20 are stacked. Tolerance is large.

(Fifth embodiment)
Hereinafter, the opto-electric hybrid board 100 according to the present embodiment shown in FIG. 6 will be described. The description will focus on differences from the above-described embodiment, and description of similar matters will be omitted. In FIG. 6, components similar to those in the above-described embodiment are denoted by the same reference numerals as those in FIG. 1 described above, and detailed description thereof is omitted. In FIG. 6, light 9 indicates the traveling direction of the light 9 when the light receiving unit or the light emitting unit 4 functions as the light emitting unit.

The optical element mounting substrate 10 shown in FIG. 6 is the same as that shown in FIG. 2 except that the light receiving portion or the light emitting portion 4 is provided on the upper surface of the optical element 3 and the optical circuit layer 20 is laminated on the optical element mounting substrate 10. This is the same as the embodiment shown.
That is, in the optical element mounting substrate 10 of the embodiment shown in FIG. 2, the light receiving part or the light emitting part 4 is disposed on the lower surface of the optical element 3 and the optical element mounting substrate on the upper surface of the optical circuit layer 20, as shown in FIG. As shown in FIG. 6, the optical element mounting substrate 10 of this embodiment is an optical circuit layer 20 on the upper surface of the optical element mounting substrate 10. This is an optical element mounting substrate that is assumed to be laminated and optically connected.
With such a configuration, the element can be mounted on the surface of the electric circuit layer 20 opposite to the surface on which the optical element 3 is mounted.
In addition to the above-described operations and effects, the present embodiment can provide the same operations and effects as the above-described embodiments.

<Method for manufacturing opto-electric hybrid board>
Next, an example of a method for manufacturing the opto-electric hybrid board 100 as described above will be described.
The opto-electric hybrid board 100 shown in FIG. 1 is manufactured by preparing the optical element mounting board 10 and the optical circuit layer 20 and laminating them, and then processing the obtained laminate.

Hereinafter, a method for manufacturing the opto-electric hybrid board 100 will be sequentially described.
[1] Manufacture of Optical Waveguide Structure First, a method for manufacturing the optical element mounting substrate 10 used for manufacturing the opto-electric hybrid substrate 100 will be described.

[1-1] Production of Electric Circuit Layer An insulating substrate 1 is prepared, and an electric circuit layer 2 is formed so as to cover part or all of the upper surface thereof.
This electric circuit layer 2 is a film having the above-described metal composition, and such a film is formed by chemical vapor deposition such as plasma CVD, thermal CVD, or laser CVD, physical vapor deposition such as vacuum vapor deposition, sputtering, or ion plating, electrolysis. It is formed by a plating method such as plating or electroless plating, a thermal spraying method, a sol-gel method, a MOD method, or the like.
Next, the electric circuit layer 2 is patterned by various patterning methods. Examples of the patterning method include a method in which a photolithography method and an etching method are combined.
As described above, the electric circuit layer (electric wiring) 2 is formed on the insulating substrate 1.
The method for forming the electric circuit layer 2 is not limited to the above method, and a conductive paste, a conductive ink, or the like is supplied to a predetermined region on the upper surface of the insulating substrate 1 (along the pattern of the electric wiring 2). Then, a method of drying may be used. Examples of the supply method include various printing methods and various coating methods.

[1-2] Formation of a recess Next, a recess is formed in the optical element mounting substrate 10.
The formation of the recess can be performed by various processing methods such as a laser processing method, an electron beam processing method, and a machining method. According to the laser processing method, since the processing can be performed with high accuracy, the positional accuracy of the concave portion can be increased. As a result, the optical axis of the core portion 211 and the optical axis of the optical element 3 inserted into the recess can be accurately aligned to obtain an opto-electric hybrid board with low propagation loss.

Further, according to the laser processing method, since the processing rate varies depending on the composition of the material to be processed, only a specific layer can be selectively processed using the processing rate. By utilizing this characteristic, the optical element mounting substrate 10 can be selectively processed while the electric circuit layer 2 can be left without being processed. This is because the electric circuit layer 2 is made of a metal-based material, so that the processing rate in laser processing is smaller than other materials. The above characteristics are particularly remarkable when each insulating substrate 1 is made of an organic material.
Further, in order to selectively process only a specific layer, laser processing conditions are appropriately set according to the constituent materials of the electric circuit layer 2 and the insulating substrate 1.
An example of processing conditions, the power density of the laser is preferably in the range of about 30~1000mJ / cm ^2, more preferably about 50~700mJ / cm ^2. Thereby, when the optical element mounting substrate 10 is subjected to laser processing, the insulating substrate 1 can be selectively processed while the electric circuit layer 2 is reliably left.
The laser oscillator is not particularly limited, and examples thereof include a carbon dioxide laser, an excimer laser, an Ar laser, a He—Ne laser, a YAG laser, and a semiconductor laser.

Further, according to the laser processing method, the flatness and smoothness of the processed surface are enhanced. This is considered to be because the optical element mounting substrate 10 in the processing region is slightly melted by the heat of the laser and the unevenness is averaged. When the flatness and smoothness of the processed surface are improved, the surface accuracy of the bottom surface of the recess, in other words, the surface accuracy of the recess through which the propagation light passes can be improved, and the light incident efficiency and the light emission efficiency can be increased.
Furthermore, since the unevenness of the inner surface of the recess is reduced when the flatness and smoothness of the processed surface are increased, the distance between the recess and the optical element 3 can be reduced accordingly. Thereby, the separation distance between the light receiving part or the light emitting part 4 and the exposed surface of the core part 211 is reduced, and not only can the coupling loss between the two be minimized, but also the room for shifting the position of the optical element 3 in the recess. Can be minimized. Further, since the laser irradiation region is removed by vaporization, there is an advantage that generation of cutting waste and burrs is prevented.

[1-3] Mounting of optical element The optical element mounting substrate 10 has a recess into which the optical element 3 can be inserted, and the optical element 3 and the electric circuit layer are inserted by inserting the optical element 3 into the recess. The optical connection between the optical element 3 and the optical circuit layer 20 to be laminated later is enabled at the same time.
After the optical element 3 and the electric circuit layer 2 are electrically connected by the method described above, an underfill agent is poured into the concave portion and cured to fix the position of the optical element 3.
Furthermore, if necessary, an electronic component (not shown) is placed on the optical element mounting substrate 10 to electrically connect the electric circuit layer 2 and the electronic component.
Examples of the electronic component include an LSI (Large Scale Integration), an IC (Integrated Circuit), a memory, a resistor, and a capacitor. These electronic components may have a function of controlling driving of the optical element 3.
Through these steps, the optical element mounting substrate 10 is obtained.

[2] Production of Optical Circuit Layer First, the clad layer 220, the core layer 210, and the clad layer 230 are produced. After forming the liquid film by applying the composition for forming each layer on the base material, the base material is placed on a level table to level the uneven portion of the liquid film surface. Formed by evaporation (desolvation) of the solvent.
Examples of the coating method for forming the liquid film include a doctor blade method, a spin coating method, a dipping method, a table coating method, a spray method, an applicator method, a curtain coating method, and a die coating method.
In addition, as a method of forming the core part 211 and the side cladding part 212 in the same layer (core layer 210), for example, a photo bleaching method, a photolithography method, a direct exposure method, a nanoimprinting method, a monomer diffusion, and the like. Law.
Thereafter, the formed clad layer 220, core layer 210 and clad layer 230 are pressure-bonded to each other. Thereby, the clad layer 220, the core layer 210, and the clad layer 230 are joined and integrated, and the optical waveguide 200 is obtained. Although the optical waveguide 200 can be used as the optical circuit layer 20, it may be the optical circuit layer 20 provided with a cover film, an insulating substrate, or the like. When the insulating substrate is provided, the same substrate as the insulating substrate 1 used for the optical element mounting substrate 10 can be used.

[3] Lamination of optical element mounting substrate and optical circuit layer Next, the optical element mounting substrate 10 and the optical circuit layer 20 are laminated.
The insulating substrate 1 and the optical circuit layer 20 and the electric circuit layer 2 and the optical circuit layer 20 are bonded by a method such as thermocompression bonding or bonding with various adhesives (including adhesive). However, when the clad layer 220 and the clad layer 230 have adhesiveness, the adhesiveness may be used for adhesion.
Examples of the adhesive include acrylic adhesives, urethane adhesives, silicone adhesives, and various hot melt adhesives (polyester and modified olefins). Moreover, as a thing with especially high heat resistance, thermoplastic polyimide adhesive agents, such as a polyimide, a polyimide amide, a polyimide amide ether, a polyester imide, a polyimide ether, are mentioned.
As described above, the opto-electric hybrid board 100 shown in FIG. 1 in which the optical element mounting board 10 and the optical circuit layer 20 are laminated is obtained.

<Electronics>
The electronic device including the optical element mounting substrate or the opto-electric hybrid board of the present invention (electronic device of the present invention) can be applied to any electronic device that performs signal processing of both optical signals and electrical signals. Application to electronic devices such as router devices, WDM devices, mobile phones, game machines, personal computers, televisions, home servers, etc. is preferable. In any of these electronic devices, it is necessary to transmit a large amount of data at high speed between an arithmetic device such as an LSI and a storage device such as a RAM. Therefore, by providing such an electronic device with the opto-electric hybrid board according to the present invention, problems such as noise and signal deterioration peculiar to the electric wiring are eliminated, and a dramatic improvement in the performance can be expected.
In addition, the amount of heat generated in the optical waveguide portion is greatly reduced compared to electrical wiring. For this reason, the degree of integration in the substrate can be increased, the power required for cooling can be reduced, and the power consumption of the entire electronic device can be reduced.

As described above, the embodiments of the optical element mounting substrate, the opto-electric hybrid board, and the electronic device according to the present invention have been described. However, the present invention is not limited to this, and for example, the components constituting the optical element hybrid board are the same. It can be replaced with any structure that can exhibit the above function. Moreover, arbitrary components may be added.
In FIG. 7, the optical waveguide 200 (single channel) having one core 211 is described, but the present invention can also be applied to an optical circuit (multichannel) having a plurality of cores 211. .

DESCRIPTION OF SYMBOLS 1 Insulating substrate 10 Optical element mounting substrate 100 Opto-electric hybrid board 2 Electric circuit layer (electrical wiring)
DESCRIPTION OF SYMBOLS 20 Optical circuit layer 200 Optical waveguide 210 Core layer 211 Core part 212 Side surface clad part 213 Optical path conversion part 220, 230 Cladding layer 3 Optical element 4 Light receiving part or light emission part 5 Electrode 51 Wire bonding 6 Through hole 7 Underfill 8 Through hole 9 light

Claims (16)

An optical element mounting substrate on which an optical element laminated with an optical circuit layer in which an optical waveguide is formed and having a light receiving part or a light emitting part is mounted,
An electric circuit layer and an insulating substrate are laminated, and the optical element mounting substrate has at least one recess in the thickness direction on the electric circuit layer side or the insulating substrate side, and at least the optical element A part of the optical element mounting substrate, wherein a part thereof is housed in the recess.   The optical element mounting substrate according to claim 1, wherein the insulating substrate and the electric circuit layer in the recess have a thickness of 1 μm to 10 μm.   3. The optical element mounting substrate according to claim 1, wherein at least a part of a light receiving portion or a light emitting portion of the optical element does not overlap with an electric wiring in the electric circuit layer in the stacking direction of the optical element mounting substrate. .   4. The optical element mounting substrate according to claim 1, wherein the insulating substrate is laminated on the electric circuit layer.   The optical element mounting substrate according to any one of claims 1 to 4, wherein an underfill agent is filled in the gap between the concave portion and the optical element mounted in the concave portion and cured.   The optical element mounting substrate according to claim 5, wherein the underfill agent is selected from the group consisting of a resin having a transmittance of 90% or more at a wavelength of light used by the optical element after curing.   7. The optical element mounting substrate according to claim 1, wherein the constituent material of the insulating substrate is transparent at a wavelength of light used by the optical element.   The optical element mounting substrate according to any one of claims 1 to 7, wherein the constituent material of the insulating substrate is selected from the group consisting of polyimide, polyamide, polyamideimide, polyester, glass cloth epoxy substrate, and glass substrate.   9. The optical element mounting substrate according to claim 1, wherein an area of the concave portion is 1.1 to 3 times as large as an area of the optical element in a top view.   The optical element mounting substrate according to claim 1, wherein the optical element and the electric circuit layer are electrically connected through a through hole formed in the insulating substrate.   The optical element mounting substrate according to any one of claims 1 to 10, wherein the insulating substrate has a through hole that overlaps at least a part of a light receiving portion or a light emitting portion in the stacking direction of the optical element mounting substrate.   12. An opto-electric hybrid board, wherein the optical element mounting board according to claim 1 is laminated on one surface of an optical circuit layer on which an optical waveguide is formed.   The opto-electric hybrid board according to claim 12, wherein a distance between the light receiving part or the light emitting part and the upper surface of the optical circuit layer is 1 μm to 50 μm.   The opto-electric hybrid board according to claim 12 or 13, wherein the optical waveguide is formed of a material containing a cyclic olefin resin.   An electronic device comprising the optical element mounting substrate according to claim 1.   An electronic apparatus comprising the opto-electric hybrid board according to claim 12.