JP5493626B2 - Opto-electric hybrid board and electronic equipment - Google Patents

Description

The present invention relates to an opto- electric hybrid board and an electronic apparatus.

  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.

  By the way, electric wiring for supplying electric power is indispensable for driving each element such as a light emitting element and a light receiving element which perform 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.

  For example, Patent Document 1 discloses an optical / electrical wiring hybrid circuit module having a fine wiring circuit part, an optical wiring circuit part, and an optical element.

However, the circuit module described in Patent Document 1 has the following problems.
1. Since the optical element is mounted on the fine wiring circuit portion formed in multiple layers, the thickness of the entire circuit module is increased, and the demand for thinning cannot be met.
2. Since the optical element and the semiconductor chip are mounted so as to protrude from the upper surface of the fine wiring circuit portion, they are structured to easily receive an external force due to interference with other members. Depending on the magnitude of the external force, the optical element or the semiconductor chip may break down or fall off.

JP 2004-146602 A

An object of the present invention is to reliably protect an optical element from external force and to reduce the thickness of an opto-electric hybrid board while connecting the optical element and the optical waveguide with low loss when laminated with the optical waveguide. to provide an opto-electric hybrid board and an electronic device with a realizable optical device mounting board.

Such an object is achieved by the present inventions (1) to (13) below.
(1) A flexible first substrate, an electrical wiring provided on the first substrate, and a light receiving unit or light emitting unit placed on the first substrate and facing the first substrate an optical element having a part, is placed on the first substrate so as to surround the periphery of the optical element, and a second substrate having high rigidity than the first substrate, the second substrate A through-hole penetrating in the thickness direction; a through-via structure provided in the through-hole and electrically connected to the electrical wiring; and a surface of the second substrate electrically connected to the through-via structure A bump provided so as to protrude from the optical element mounting substrate,
An optical waveguide comprising a linear core portion and a cladding portion provided so as to cover a side surface of the core portion, and laminated with the optical element mounting substrate so as to be in contact with the first substrate;
Optical path changing means for optically connecting the optical element and the optical waveguide;
A mounting substrate comprising: an insulating substrate; and a wiring pattern provided on the insulating substrate;
Have
The opto-electric hybrid board, wherein the optical element mounting board and the mounting board are laminated so that the bump and the wiring pattern are in contact with each other.

(2) The opto-electric hybrid board according to (1), wherein each of the first substrate and the electrical wiring includes an extending portion that extends to the outside of the second substrate.
(3) The opto-electric hybrid board according to (1) or (2) , wherein the second substrate has a frame shape surrounding the entire circumference of the optical element.

(4) The opto-electric hybrid board according to any one of (1) to (3) , wherein the thickness of the second substrate is thicker than the thickness of the optical element.

(5) The opto-electric hybrid board according to any one of (1) to (4) , wherein an average thickness of the first substrate is 5 to 50 μm.

(6) the optical element mounting substrate further the provided inside of the second substrate, the light according to any one of (1) to a control device for controlling the operation of said optical element (5) Electric mixed board .

(7) In any one of the above (1) to (6) , at least a part of a space defined by the upper surface of the first substrate and the inner surface of the second substrate is filled with a sealing resin. The opto-electric hybrid board described.

(8) The opto-electric hybrid board according to (7) , wherein the sealing resin is filled so as to cover the entire optical element.

(9) The opto-electric hybrid board according to any one of (1) to (8), wherein the optical element mounting board is laminated on one end part or both end parts of the optical waveguide.

(10) The optical element mounting substrate is provided at one end of the optical waveguide,
The opto-electric hybrid board according to any one of (1) to (9) , wherein the opto-electric hybrid board is provided at the other end of the optical waveguide and includes a connector for connecting the optical waveguide to a connection partner.

(11) the first substrate and the electric wiring includes a stretching portion respectively extending outwardly of the second substrate, stretched portion is bent in the middle, the second of said optical waveguide The opto-electric hybrid board according to any one of the above (1) to (10) , which is configured to cover from the board side surface to the opposite side surface .
(12) Each of the first substrate and the electrical wiring includes an extended portion that extends to the outside of the second substrate,
The opto-electric hybrid board according to any one of the above (1) to (11), further including a heat sink provided in the extending portion.

(13) An electronic device comprising the opto-electric hybrid board according to any one of (1) to (12) .

According to the present invention, since the rigid substrate is arranged so as to surround the periphery of the light emitting / receiving element, the entire thickness can be reduced and the light receiving / emitting element can be protected from external force when laminated with the optical waveguide. An opto-electric hybrid board is obtained.

  In addition, since a flexible substrate is arranged between the optical waveguide and the rigid substrate, the flexible substrate acts so as to reduce the thermal expansion difference between the optical waveguide and the rigid substrate. Problems such as delamination are prevented.

Further, by providing such an opto-electric hybrid board, high have electronic equipment reliability is obtained thin.

It is a perspective view which permeate | transmits and shows partially the embodiment of the opto-electric hybrid board | substrate of this invention. FIG. 2 is a cross-sectional view of the opto-electric hybrid board shown in FIG. It is sectional drawing which shows the other structural example of the opto-electric hybrid board shown in FIG. It is sectional drawing which shows the state which mounted the opto-electric hybrid board | substrate shown in FIG. 2 on the mounting board | substrate. It is sectional drawing which shows the other structural example of the opto-electric hybrid board shown in FIG. It is a figure (sectional drawing) for demonstrating the manufacturing method of the opto-electric hybrid board shown in FIG.

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

<Opto-electric hybrid board>
1 is a partially transparent perspective view showing an embodiment of the opto-electric hybrid board according to the present invention, FIG. 2 is a cross-sectional view taken along the line AA of the opto-electric hybrid board shown in FIG. 1, and FIG. 4 is a cross-sectional view showing another example of the opto-electric hybrid board shown in FIG. 4, FIG. 4 is a cross-sectional view showing a state in which the opto-electric hybrid board shown in FIG. 2 is mounted on a mounting board, and FIG. FIG. 6 is a cross-sectional view showing another configuration example of the hybrid substrate, and FIG. 6 is a diagram (cross-sectional view) for explaining a method of manufacturing the photoelectric hybrid substrate shown in FIG. In the following description, the upper side of FIGS. 1 to 6 is referred to as “upper” and the lower side is referred to as “lower”. In each figure, the thickness direction of the opto-electric hybrid board is emphasized.

  An opto-electric hybrid board 1 shown in FIG. 1 includes an optical circuit layer 2 on which an optical waveguide 21 is formed, and an optical element mounting board (an opto-electric composite module) provided above and including a light receiving / emitting element (optical element) 7. ) 10 is laminated.

  Here, the optical circuit layer 2 has a long band shape, and the optical element mounting substrate 10 is laminated on the upper surface of one end of the optical circuit layer 2.

  The optical element mounting substrate 10 is a flat plate-like first substrate 11, a second substrate 12 that is provided on the first substrate 11 and has a quadrangular frame shape, and a first inside the second substrate 12. The light emitting / receiving element 7 and the semiconductor element (control element) 8 are provided on the substrate 11.

  The light receiving / emitting element 7 converts the electrical signal into an optical signal, emits the optical signal from the light emitting unit, and enters the optical waveguide 21 or receives the optical signal emitted from the optical waveguide 21 by the light receiving unit. This is a light receiving element that converts it into an electrical signal. The light emitting / receiving element 7 shown in FIG. 2 has a light emitting / receiving unit 71 and an electrode pad 72 provided on the lower surface thereof. The light emitting / receiving unit 71 emits an optical signal downward or receives an optical signal upward. In addition, the arrow shown in FIG. 2 is an example of an optical path when the light emitting / receiving element 7 is a light emitting element.

  On the other hand, a mirror (optical path changing means) 22 is provided below the light emitting / receiving unit 71 in the optical waveguide 21. The mirror 22 can change the optical path by 45 ° so that the optical waveguide 21 extending in the left-right direction in FIG. 2 and the light receiving and emitting unit 71 provided on the optical element mounting substrate 10 are optically connected. Through such a mirror 22, an optical signal emitted from the light receiving / emitting unit 71 can be sent to the optical waveguide 21, or an optical signal propagated through the optical waveguide 21 can be incident on the light receiving / emitting unit 71. it can. As a result, optical communication is possible in the opto-electric hybrid board 1.

  In the opto-electric hybrid board 1, the light emitting / receiving elements 7 and the semiconductor elements 8 are arranged inside the second substrate 12 having a frame shape. It does not affect the thickness of the entire mixed substrate 1. In other words, since the light emitting / receiving element 7 and the semiconductor element 8 are contained in the space 13 inside the second substrate 12, the thickness of the entire opto-electric hybrid board 1 is the same as that of the second substrate 12. 1 is the sum of the thicknesses of the three layers of the substrate 11 and the optical circuit layer 2. Therefore, the opto-electric hybrid board 1 can be made thinner than the conventional one.

  Further, since the second substrate 12 is provided so as to surround the light emitting / receiving element 7 and the semiconductor element 8, these elements can be protected from external force.

Hereinafter, each part of the opto-electric hybrid board 1 will be described in detail.
(Optical circuit layer)
The optical circuit layer 2 shown in FIG. 1 includes an optical waveguide 21 in which a clad layer (lower clad layer) 211, a core layer 213, and a clad layer (upper clad layer) 212 are laminated in this order from below. . Among these, as shown in FIG. 1, the core layer 213 is formed with a linear core portion 214 in a plan view and a side cladding portion 215 adjacent to the side surface of the core portion 214. The core part 214 is provided in a straight line along the longitudinal direction of the laminated body having a band shape. In addition, the core portion 214 is located approximately at the center of the width of the core layer 213. In FIG. 1, the core portion 214 is marked with dots.

  In the optical waveguide 21 shown in FIG. 1, the light incident on one end of the core part 214 is totally reflected at the interface between the core part 214 and the clad parts (the clad layers 211 and 212 and the side clad parts 215). And can be propagated to the other 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 214 and the cladding part, a difference in refractive index needs to exist at the interface. Although the refractive index of the core part 214 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 refractive index difference is expressed by the following equation, where A is the refractive index of the core portion 214 and B is the refractive index of the cladding portion.
Refractive index difference (%) = | A / B-1 | × 100

  In the configuration shown in FIG. 1, the core portion 214 is formed in a straight line shape in a plan view, but may be curved, branched or the like in the middle, and the shape is arbitrary.

  Further, the cross-sectional shape of the core part 214 is generally a square such as a square or a rectangle (rectangle), but is not particularly limited, and is not limited to a circle, such as a perfect circle or an ellipse, a rhombus, a triangle, or a pentagon. A polygon such as

  The width and height of the core part 214 are not particularly limited, but are preferably about 1 to 200 μm, more preferably about 5 to 100 μm, and still more preferably about 20 to 70 μm.

  The constituent material of the core layer 213 is not particularly limited as long as it has the above-described refractive index difference. Specifically, acrylic resin, methacrylic resin, polycarbonate, polystyrene, epoxy resin, polyamide, polyimide, polybenzo In addition to various resin materials such as oxazole, polysilane, polysilazane, and cyclic olefin resins such as benzocyclobutene resin and norbornene resin, there are glass materials such as quartz glass and borosilicate glass.

  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).

  On the other hand, each of the cladding layers 211 and 212 constitutes a cladding portion located below and above the core layer 213, respectively. Each of the clad layers 211 and 212 constitutes a clad portion surrounding the outer periphery of the core portion 214 together with the side clad portions 215, whereby the optical waveguide 21 functions as a light guide path.

  The average thickness of the clad layers 211 and 212 is preferably about 0.1 to 1.5 times the average thickness of the core layer 213 (the average height of each core portion 214). More preferably, the average thickness of the clad layers 211 and 212 is not particularly limited, but is usually preferably about 1 to 200 μm and about 5 to 100 μm. More preferably, it is about 10 to 60 μm. Thereby, the function as a clad layer is suitably exhibited while preventing the optical circuit layer 2 from becoming unnecessarily large (thickened).

  Moreover, as a constituent material of each clad layer 211 and 212, the same material as the constituent material of the core layer 213 mentioned above can be used, for example, but a norbornene-based polymer is particularly preferable.

  Further, when selecting the constituent material of the core layer 213 and the constituent materials of the clad layers 211 and 212, the material may be selected in consideration of the difference in refractive index between them. Specifically, the refractive index of the constituent material of the core layer 213 is sufficiently larger than the refractive index of the cladding layers 211 and 212 in order to ensure total reflection of light at the boundary between the core layer 213 and the cladding layers 211 and 212. What is necessary is just to select a material so that it may become. As a result, a sufficient refractive index difference is obtained in the thickness direction of the optical circuit layer 2, and leakage of light from the core portion 214 to the cladding layers 211 and 212 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 213 and the constituent materials of the cladding layers 211 and 212 is high.

  As described above, the mirror 22 is provided in the middle of the optical waveguide 21 (see FIG. 2). This mirror 22 is formed on the inner wall surface of the space (cavity) obtained by digging in the middle of the optical waveguide 21. A part of this inner wall surface is a plane that crosses the core portion 214 at an angle of 45 °, and this plane becomes the mirror 22. The optical waveguide 21 and the light emitting / receiving unit 71 are optically connected via the mirror 22.

  In addition, you may make it form a reflecting film in the mirror 22 as needed. As the reflective film, a metal film such as Au, Ag, or Al is preferably used.

(Optical device mounting substrate)
An optical element mounting substrate 10 is provided above the optical circuit layer 2.

  As described above, the optical element mounting substrate 10 includes the first substrate 11, the second substrate 12, the light emitting and receiving element 7, and the semiconductor element 8.

  The first substrate 11 is provided such that the lower surface thereof is in contact with the upper surface of the optical circuit layer 2, and the light emitting / receiving element 7 and the semiconductor element 8 are provided on the first substrate 11.

  As described above, since the optical path connecting the light emitting / receiving portion 71 of the light emitting / receiving element 7 and the optical waveguide 21 penetrates the first substrate 11 in the thickness direction, the first substrate 11 is translucent. It is preferable that it is comprised with the material which has this. This improves the transmission efficiency of the optical path. In the case where the first substrate 11 is made of a material with low translucency, a through hole may be provided in accordance with the optical path.

  In addition, since the first substrate 11 has flexibility, the adhesion to the optical waveguide 21 is high. This is because the flexible first substrate 11 has a high shape followability, and thus exhibits excellent adhesion even if the upper surface of the optical waveguide 21 is not a flat surface. Further, even when the opto-electric hybrid board 1 is bent, the first substrate 11 can also be bent in accordance with the curve of the optical waveguide 21, so that a decrease in adhesion is prevented. Furthermore, since it is difficult for a gap to occur at the close contact interface, there is an advantage that a reduction in transmission efficiency on the optical path is prevented.

  The flexible material selected as the constituent material of the first substrate 11 has a thermal expansion coefficient of the constituent material of the second substrate 12 and the constituent material (optical waveguide material) of the optical circuit layer 2 described later. Therefore, the first substrate 11 is positioned as an intermediate layer between the second substrate 12 and the optical circuit layer 2. As described above, since the first substrate 11 has flexibility, the first substrate 11 has a function of relaxing deformation stress generated between the layers. That is, the first substrate 11 is free from peeling, destruction, etc. due to thermal history by relaxing the accumulation of stress that can occur between layers based on the difference in thermal expansion in the manufacturing process, mounting process, or actual use environment. It can be surely prevented.

  The Young's modulus (tensile modulus) of the first substrate 11 is preferably about 1 to 20 GPa and more preferably about 2 to 12 GPa in a general room temperature environment (around 20 to 25 ° C.). preferable. If the range of the Young's modulus is about this level, the first substrate 11 has sufficient flexibility to obtain the effects described above.

  Examples of the material constituting the first substrate 11 include various resin materials such as polyimide resins, polyamide resins, epoxy resins, various vinyl resins, and polyester resins such as polyethylene terephthalate resins. However, among these, those mainly composed of a polyimide resin are preferably used. The polyimide resin is particularly suitable as a constituent material of the first substrate 11 because of its high heat resistance and excellent translucency and flexibility.

  In addition, as a specific example of the 1st board | substrate 11, the film board | substrate used for a polyester copper-clad film board | substrate, a polyimide copper-clad film board | substrate, an aramid copper-clad film board | substrate, etc. are mentioned.

  The average thickness of the first substrate 11 is preferably about 5 to 50 μm, and more preferably about 10 to 40 μm. If it is the 1st board | substrate 11 of such thickness, it will have sufficient flexibility irrespective of the constituent material. If the thickness of the first substrate 11 is within the above range, the opto-electric hybrid board 1 can be thinned and the distance between the light emitting / receiving unit 71 and the optical waveguide 21 can be sufficiently shortened. The transmission loss of the first substrate 11 can be suppressed.

  Furthermore, if the thickness of the first substrate 11 is within the above range, it is possible to prevent the transmission efficiency from being lowered due to the divergence of the optical signal. For example, after propagating through the optical waveguide 21, the light reflected upward by the mirror 22 can reach the light emitting / receiving unit 71 before being widely diffused. For this reason, it can prevent that the light quantity which reaches | attains the light emitting / receiving part 71 decreases, and can raise the S / N ratio of optical communication. For the above reason, a lens for converging the optical signal is not necessary, so that the structure of the opto-electric hybrid board 1 can be simplified and the manufacturing yield can be improved.

  On the other hand, when the light emitting / receiving unit 71 is a light emitting unit, it can reach the mirror 22 before the emitted light diverges.

A second substrate 12 is stacked on the first substrate 11.
The second substrate 12 is a substrate having higher rigidity than the first substrate 11. Specifically, the Young's modulus (flexural modulus) of the second substrate 12 is preferably about 5 to 50 GPa in a general room temperature environment (around 20 to 25 ° C.), and is about 12 to 30 GPa. Is more preferable. If the range of the Young's modulus is about this level, the second substrate 12 can more reliably exhibit the effects described above.

  Further, as described above, the second substrate 12 is a substrate having a quadrangular frame shape. However, this frame does not necessarily have to be a closed frame, and may be a partially opened frame. . In this case, it is preferable that one of the four sides of the quadrangle is one side or less than the length thereof. Thereby, the 2nd board | substrate 12 can fully exhibit the effect. In addition, from the viewpoint of improving mounting accuracy and workability when mounting the second substrate 12 on another electric substrate, the second substrate 12 has a concave portion, a convex portion, a hole portion or a notch portion for alignment. It may be provided.

  As a material constituting such second substrate 12, for example, paper, glass cloth, resin film or the like is a base material, and this base material includes phenolic resin, polyester resin, epoxy resin, cyanate resin, What impregnated resin materials, such as a polyimide-type resin and a fluorine-type resin, is mentioned.

  Specifically, in addition to insulating substrates used in glass-based copper-clad laminates such as glass cloth and epoxy copper-clad laminates, and composite copper-clad laminates such as glass nonwoven fabrics and epoxy copper-clad laminates, polyethers Examples thereof include heat-resistant and thermoplastic organic rigid substrates such as imide resin substrates, polyetherketone resin substrates, and polysulfone resin substrates, and ceramic rigid substrates such as alumina substrates, aluminum nitride substrates, and silicon carbide substrates.

  The average thickness of the second substrate 12 is not particularly limited, but is preferably about 300 μm to 3 mm, more preferably about 500 μm to 2.5 mm. Since the second substrate 12 having such a thickness has sufficient rigidity and is thicker than the light emitting / receiving element 7 and the semiconductor element 8, they can be surely enclosed. As a result, the light emitting / receiving element 7 and the semiconductor element 8 are contained in the space 13 inside the second substrate 12, and these elements affect the thickness of the entire opto-electric hybrid board 1. Is prevented. As a result, the opto-electric hybrid board 1 can be reliably reduced in thickness.

  The second substrate 12 may be a single substrate or a multilayer substrate (build-up substrate) formed by stacking a plurality of substrates. In this case, a patterned conductive layer is included between the layers of the multilayer substrate, and an arbitrary electric circuit may be formed. As a result, even if the second substrate 12 has a small area, a complicated electric circuit can be built inside, and the circuit density can be increased.

  Further, as shown in FIGS. 1 and 2, the second substrate 12 is provided with a plurality of cylindrical through holes 121 that penetrates in the thickness direction. These through holes 121 are arranged in a line at equal intervals over the entire circumference of the second substrate having a frame shape.

  Each through-hole 121 is filled with a conductive material, or a film of a conductive material is formed along the inner wall surface. Thereby, a through via structure 151 is formed in each through hole 121.

  A connection terminal 152 electrically connected to each through via structure 151 and a bump 153 provided on each connection terminal 152 are provided in the opening of each through hole 121 (in the vicinity of the upper opening end). Yes.

  On the other hand, a wiring pattern (electric wiring) 15 made of a conductive material is provided on the first substrate 11. With the wiring pattern 15, the electrode pad 72 of the light emitting / receiving element 7 and the electrode pad 82 of the semiconductor element 8 are connected to each through via structure 151. Therefore, external driving power and control signals can be sent to the light emitting / receiving element 7 and the semiconductor element 8 via the bump 153, the connection terminal 152, the through via structure 151, and the wiring pattern 15.

  Examples of the conductive material used for the connection terminal 152, the through via structure 151, and the wiring pattern 15 include aluminum (Al), copper (Cu), gold (Au), silver (Ag), platinum (Pt), nickel ( Examples thereof include various metal materials such as Ni), tungsten (W), and molybdenum (Mo).

  The through via structure 151 is formed by, for example, forming a conductive film on the inner wall surface of the through hole 121 by various plating methods.

  Moreover, although the average thickness of the wiring pattern 15 is appropriately set according to the constituent material of the wiring pattern 15, the electrical resistance value required for the wiring pattern 15, and the like, it is about 1 to 30 μm as an example.

  Moreover, although the width of the wiring pattern 15 is appropriately set according to the constituent material of the wiring pattern 15, the electrical resistance value required for the wiring pattern 15, and the like, it is preferably about 2 to 1000 μm as an example. More preferably, it is about 500 μm.

  Note that such a wiring pattern 15 is formed by, for example, patterning a conductive layer once formed on the entire surface (for example, patterning a copper foil of a copper-clad substrate), a conductive layer patterned in advance on a separately prepared substrate. It is formed by a transfer method or the like.

  The connection terminal 152 provided in the opening of each through hole 121 may be the upper end surface of each through via structure 151, or may be a pad with a larger area connected to the upper end surface.

  The bumps 153 provided on the connection terminals 152 are ball-shaped or land-shaped electrodes made of various solders, various brazing materials, and the like.

  Among them, as solder or 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.

  The bumps 153 are electrodes that are responsible for connection when the opto-electric hybrid board 1 is electrically connected to other members. With the bump 153, the opto-electric hybrid board 1 can be mounted in a BGA (Ball Grid Array) type or an LGA (Land Grid Array) type.

  Further, when the connection terminal 152 comes into contact with the solder (or brazing material), there is a possibility that a part of the metal component constituting the connection terminal 152 is dissolved on the solder side. This phenomenon is called “copper erosion” because it often occurs particularly for copper terminals. When copper erosion occurs, there is a risk that the connection terminal 152 may be thinned or damaged, and the function of the connection terminal 152 may be impaired.

  Therefore, it is preferable to previously form a copper erosion prevention film (underlayer) as a solder underlayer on the surface of the connection terminal 152 in contact with the conductive material. By forming the copper erosion prevention film, copper erosion is prevented, and the function of the connection terminal 152 can be maintained for a long 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.

  As described above, the light emitting / receiving element 7 provided inside the second substrate 12 has the light emitting / receiving portion 71 and the electrode pad 72 on the lower surface. Specifically, the surface emitting laser (VCSEL) is used. A light emitting element such as a light emitting diode (LED), and a light receiving element such as a photodiode (PD, APD).

  On the other hand, the semiconductor element 8 adjacent to the light emitting / receiving element 7 is an element for controlling the operation of the light emitting / receiving element 7, and has an electrode pad 82 on the lower surface. Examples of the semiconductor element 8 include a combination IC including a driver IC, a transimpedance amplifier (TIA), a limiting amplifier (LA), and various LSIs and RAMs.

  As a result of placing the light emitting / receiving element 7 and the semiconductor element 8 on the inner side of the frame-like second substrate 12 in this way, even if an external force is applied to the optical element mounting substrate 10 from the outside, the second External force is received by the substrate 12, and external force is prevented from being applied to these elements. As a result, troubles such as failure and dropout occurring in the light emitting / receiving element 7 and the semiconductor element 8 are prevented, and the highly opto-electric hybrid board 1 can be obtained. In particular, since the second substrate 12 is provided so as to surround the entire circumference of the light emitting / receiving element 7 and the semiconductor element 8, each element can be protected against external forces from all directions.

  The connection between the electrode pad 72 of the light emitting / receiving element 7 and the wiring pattern 15 and the connection between the electrode pad 82 of the semiconductor element 8 and the wiring pattern 15 are connections in which the electrode pad and the wiring pattern are overlapped as described above. It is not limited to a method, For example, you may connect by a wire bonding technique.

  According to the wire bonding, in the electrical connection between the electrode pad and the wiring pattern, the difference in thermal expansion between the two connected can be ignored. For example, when the optical element mounting substrate 10 is deformed with a thermal history, even if a difference in deformation occurs between the electrode pad and the wiring pattern, the highly flexible bonding wire absorbs this difference. There is also an advantage that the electrical connection between the electrode pad and the wiring pattern is reliably maintained. The electrical connection between the electrode pad and the wiring pattern is not limited to these methods, and for example, a method using an anisotropic conductive film (ACF) or an anisotropic conductive paste (ACP) may be used.

  Further, in the space 13 defined by the upper surface of the first substrate 11 and the inner surface of the second substrate 12, a molding resin (sealing resin) is provided so as to cover at least the entire light emitting / receiving element 7 and the entire semiconductor element 8. 14 is filled. The mold resin 14 reliably protects the light emitting / receiving element 7 and the semiconductor element 8 from weather resistance (heat resistance, moisture resistance, atmospheric pressure change, etc.), vibration, external force, stress concentration, foreign matter adhesion, and the like.

  Note that the wiring pattern 15, the electrode pad 72 of the light emitting / receiving element 7, and the electrode pad 82 of the semiconductor element 8 each have a predetermined thickness, and thus when placed on the upper surface of the first substrate 11. These element main bodies are slightly lifted from the upper surface of the first substrate 11. As a result, a gap is formed between these elements and the upper surface of the first substrate 11, but the mold resin 14 also enters the gap and fills the gap.

  In this case, since the mold resin 14 is also present on the optical path, it is preferable to have as high a translucency as possible. Further, in order to increase the translucency of the interface between the mold resin 14 and the first substrate 11, the mold resin 14 preferably has a refractive index close to that of the first substrate 11. Specifically, the refractive index difference between the two is preferably 0.05 or less.

  Examples of the mold resin 14 include an epoxy resin, a polyester resin, and a polyurethane resin.

  Further, in the optical element mounting substrate 10, the bottomed space 13 is filled with the mold resin 14, so that the filled mold resin 14 does not flow out of the space 13 even when uncured. For this reason, the viscosity of the mold resin 14 at the time of filling does not need to be particularly controlled, and the filling operation is easy.

  Note that an underfill agent may be filled in the gap between the light emitting / receiving element 7 and the first substrate 11 or in the gap and its periphery. As this underfill agent, a material having translucency is used, and specifically, a material mainly composed of an epoxy resin or a silicone resin is preferably used. Further, when an underfill agent is used, the mold resin 14 filled from above does not necessarily have translucency.

  The optical element mounting substrate 10 as described above has the advantage that the opto-electric hybrid board 1 having a high optical signal transmission efficiency can be manufactured very simply by simply laminating its lower surface so as to be in contact with the optical circuit layer 2. Have

  Note that the first substrate 11 and the wiring pattern 15 of the optical element mounting substrate 10 each preferably have an extended portion 16 extending outside the second substrate 12. Specifically, as shown in FIG. 3, the first substrate 11 and the wiring pattern 15 extend to the outside of the second substrate 12, and the extended portion 16 extends along the end face of the optical circuit layer 2. Then, it is bent 90 ° downward and is further bent 90 ° to be laminated on the lower surface of the optical circuit layer 2. In such an extended portion 16, since the wiring pattern 15 is exposed, it is possible to efficiently dissipate heat through the wiring pattern 15. That is, since the wiring pattern 15 has high thermal conductivity, it efficiently propagates the heat generated from the light emitting / receiving element 7 and the semiconductor element 8 and dissipates heat at the extended portion 16 to function as a heat radiator. Thereby, it is possible to prevent the light emitting / receiving element 7 and the semiconductor element 8 from being overheated and to prevent deterioration of the characteristics of the element due to heat. Note that the optical element mounting substrate 10 shown in FIG. 3 is the same as the optical element mounting substrate 10 shown in FIG.

  The line width of the wiring pattern 15 located in the extended portion 16 is preferably wider than that of the wiring pattern 15 located in the space 13, and is provided so as to cover the entire first substrate 11 located in the extended portion 16. More preferably. Thereby, since the area which contributes to heat radiation in the wiring pattern 15 becomes large, heat radiation efficiency can be improved.

  Furthermore, the heat radiation efficiency can be further increased by increasing the thickness of the wiring pattern 15 or forming irregularities on the surface.

  As a result of bending the extended portion 16, the extended portion 16 functions as an electromagnetic shield that covers the lower part of the optical element mounting substrate 10. As a result, it is possible to prevent electromagnetic noise from the external space from being superimposed on the electric signal flowing through the wiring pattern 15, and conversely, prevent the electric signal flowing through the wiring pattern 15 from leaking into the external space.

  Further, a heat sink 17 is provided in the extended portion 16 shown in FIG. With this heat sink 17, the heat dissipation of the extended portion 16 can be further enhanced. The heat sink 17 is a block body made of a material having high thermal conductivity such as copper or aluminum, and preferably has a heat radiating fin.

  Further, the extending portion 16 may be laminated on the mounting substrate side on which the opto-electric hybrid board 1 is mounted. For example, the opto-electric hybrid board 1 shown in FIG. 4 is mounted on the mounting board 9 via the bumps 153.

  The mounting substrate 9 includes an insulating substrate 91 and a wiring pattern 92 provided on the lower surface of the insulating substrate 91. The opto-electric hybrid board 1 is mounted so that the bumps 153 and the wiring pattern 92 are in contact with each other, and thereby the wiring pattern 92 and the wiring pattern 15 are electrically connected.

  4 includes a heat sink 93 provided with heat radiating fins 930 provided therebelow and an insulating substrate 94 that insulates between the heat sink 93 and the wiring pattern 92. On the other hand, the extending portion 16 of the opto-electric hybrid board 1 shown in FIG. 4 extends horizontally to the left and is laminated on the lower surface of the heat sink 93. Thereby, the heat dissipation of the extending | stretching part 16 is improved more.

  The counterpart to which the extended portion 16 is laminated is not limited to the heat sink 93, but may be the insulating substrate 91, the wiring pattern 92, or the like, or other housing not shown. Further, the optical element mounting substrate 10 shown in FIG. 4 is the same as the optical element mounting substrate 10 shown in FIG. 3 except that the configuration of the extending portion 16 is different.

  The optical element mounting substrate 10 may be stacked on one end of the optical circuit layer 2 or may be stacked on both ends.

  An opto-electric hybrid board 1 shown in FIG. 5A is formed by laminating optical element mounting boards 10 on both ends of the optical circuit layer 2. In addition, mirrors 22 are respectively formed corresponding to the laminated portions of the optical element mounting substrate 10. Thereby, in the opto-electric hybrid board 1, an optical signal is generated from the electrical signal in one optical element mounting board 10, and the obtained optical signal is propagated to the other optical element mounting board 10 in the optical circuit layer 2. The other optical element mounting substrate 10 generates an electrical signal from the received optical signal. In this way, data communication using an optical signal can be performed between both ends.

  On the other hand, in the opto-electric hybrid board 1 shown in FIG. 5B, the optical element mounting substrate 10 is laminated on one end of the optical circuit layer 2, and the optical circuit layer 2 is placed on the other end. And a connector 20 for connecting to the connection partner. Examples of the connector 20 include a PMT connector used for connection with an optical fiber. That is, when the connector 20 is connected to, for example, an optical fiber, the optical waveguide 21 is extended with the optical fiber, and optical communication over a longer distance becomes possible.

  Note that the opto-electric hybrid board 1 shown in FIG. 5 has a configuration on the premise that one end and the other end are connected in a one-to-one relationship. One-to-multiple connection is possible by interposing an optical splitter capable of branching. In this case, the optical element mounting substrate 10 may be laminated on all of the plurality of end portions, the optical element mounting substrate 10 may be partially laminated, and the rest may be provided with the connector 20. All of the connectors 20 may be provided.

<Method for manufacturing opto-electric hybrid board>
Next, an example of a method for manufacturing the opto-electric hybrid board 1 as described above will be described.

  The opto-electric hybrid board 1 shown in FIG. 1 is manufactured by preparing an optical circuit layer 2 and an optical element mounting board 10 and laminating them.

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

[1-1] Production of Wiring Pattern A first substrate 11 is prepared, and a conductive layer is formed so as to cover part or all of the upper surface thereof.

  This conductive layer is a coating of the above-described metal composition, chemical vapor deposition methods such as plasma CVD, thermal CVD, and laser CVD, physical vapor deposition methods such as vacuum vapor deposition, sputtering, and ion plating, electrolytic plating, electroless plating, etc. The plating method, thermal spraying method, sol-gel method, MOD method and the like are used.

  Next, this conductive layer 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 wiring pattern 15 is formed on the first substrate 11 as shown in FIG.

[1-2] Lamination of Second Substrate Next, as shown in FIG. 6A, a second via structure in which a through via structure 151 and a connection terminal 152 are provided on the first substrate 11 provided with the wiring pattern 15 is provided. The substrate 12 is laminated.

  The first substrate 11 and the second substrate 12 are bonded by a method such as thermocompression bonding or bonding with various adhesives (including adhesive).

  Examples of the adhesive include epoxy adhesives, 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.

  Note that the wiring pattern 15 and the through via structure 151 are electrically connected by this lamination.

[1-3] Mounting of Elements Next, as shown in FIG. 6B, the light emitting / receiving element 7 and the semiconductor element 8 are mounted inside the second substrate 12. As a result, the wiring pattern 15 is electrically connected to the electrode pad 72 of the light emitting / receiving element 7 and the electrode pad 82 of the semiconductor element 8.

  Next, as shown in FIG. 6C, the mold resin 14 is supplied to the space 13 inside the second substrate 12 and solidified. Thereby, the light emitting / receiving element 7 and the semiconductor element 8 provided in the space 13 are sealed with the mold resin 14.

Next, as illustrated in FIG. 6D, bumps 153 are provided on the connection terminals 152. Such a bump 153 is formed by a method of supplying solder or a solder melt or ball onto the connection terminal 152, a method of applying a solder paste (brazing material paste), and drying.
The optical element mounting substrate 10 is obtained as described above.

[2] Production of Optical Circuit Layer First, the clad layer 211, the core layer 213, and the clad layer 212 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 214 and the side cladding part 215 in the same layer (core layer 213), 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 cladding layer 211, core layer 213, and cladding layer 212 are pressure-bonded to each other. Thereby, the clad layer 211, the core layer 213, and the clad layer 212 are joined and integrated, and the optical circuit layer 2 (optical waveguide 21) is obtained.

[3] Manufacture of opto-electric hybrid board Next, a method of manufacturing the opto-electric hybrid board 1 using the optical element mounting board 10 will be described.

  The optical circuit layer 2 and the optical element mounting substrate 10 are sequentially laminated, and the layers are bonded. Thereby, the opto-electric hybrid board 1 shown in FIG.

  Each layer is bonded by a method such as thermocompression bonding or bonding with the above-described various adhesives (including adhesives). If the clad layer 212 has adhesiveness, the adhesiveness is increased. You may make it adhere | attach using.

<Electronic equipment>
The electronic device including the opto-electric hybrid board of the present invention (the electronic device of the present invention) can be applied to any electronic device that performs signal processing of both an optical signal and an electric signal. For example, a router device, a WDM device, etc. Application to electronic devices such as 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. Therefore, the degree of integration in the substrate can be increased to reduce the size, the power required for cooling can be reduced, and the power consumption of the entire electronic device can be reduced.

  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 above. However, the present invention is not limited to this, and for example, the optical element mounting board and the opto-electric hybrid board are configured. Each part to be replaced can be replaced with one having any configuration capable of performing the same function. Moreover, arbitrary components may be added.

  For example, a cover film may be laminated on each of the upper surface and the lower surface of the optical circuit layer 2. The cover film can reliably protect the optical circuit layer 2. In addition, as a cover film, the thing similar to the 1st board | substrate 11 is used.

  In the above embodiment, the optical waveguide 21 (single channel) having one core part 214 has been described. However, the present invention can also be applied to an optical waveguide (multichannel) having a plurality of core parts 214. it can. In this case, a mirror is formed corresponding to each of the plurality of core portions 214, and the light emitting / receiving elements 7 are provided corresponding to the mirrors. The plurality of light emitting / receiving elements 7 may be arranged together inside one second substrate 12, and each light emitting / receiving element 7 is located inside each individual second substrate 12. It may be arranged.

  Further, when a light receiving / emitting element 7 having a plurality of light receiving / emitting portions 71 and a plurality of electrode pads 72 is used, one light receiving / emitting element 7 is provided so as to cross a multi-channel optical waveguide. do it.

DESCRIPTION OF SYMBOLS 1 Opto-electric hybrid board 10 Optical element mounting board 11 1st board 12 2nd board 121 Through-hole 13 Space 14 Mold resin 15 Wiring pattern 151 Through-via structure 152 Connection terminal 153 Bump 16 Extension part 17 Heat sink 2 Optical circuit layer 20 Connector 21 Optical waveguide 211, 212 Cladding layer 213 Core layer 214 Core part 215 Side cladding part 22 Mirror 7 Light emitting / receiving element 71 Light emitting / receiving part 72 Electrode pad 8 Semiconductor element 82 Electrode pad 9 Mounting substrate 91 Insulating substrate 92 Wiring pattern 93 Heat sink 930 Heat dissipation fin 94 Insulating substrate

Claims (13)

A first substrate having flexibility, an electrical wiring provided on the first substrate, and a light receiving unit or a light emitting unit mounted on the first substrate and facing the first substrate. and the optical element is mounted on the first substrate so as to surround the periphery of the optical element, the second substrate having high rigidity than that of the first substrate, the thickness direction of the second substrate A through-hole structure penetrating through the through-hole, a through-via structure provided in the through-hole and electrically connected to the electrical wiring, and electrically connected to the through-via structure and protruding from the surface of the second substrate An optical element mounting substrate comprising: a bump provided as described above;
An optical waveguide comprising a linear core portion and a cladding portion provided so as to cover a side surface of the core portion, and laminated with the optical element mounting substrate so as to be in contact with the first substrate;
Optical path changing means for optically connecting the optical element and the optical waveguide;
A mounting substrate comprising: an insulating substrate; and a wiring pattern provided on the insulating substrate;
Have
The opto-electric hybrid board, wherein the optical element mounting board and the mounting board are laminated so that the bump and the wiring pattern are in contact with each other. The first substrate and the electric wiring, an opto-electric hybrid board according to claim 1 which comprises a stretched portion which extends outwardly of the second substrate, respectively. The second substrate, the opto-electric hybrid board according to claim 1 or 2 are those frame-shaped surrounding the entire circumference of the optical element. 4. The opto-electric hybrid board according to claim 1, wherein a thickness of the second substrate is thicker than a thickness of the optical element. 5. The average thickness of the first substrate, the opto-electric hybrid board according to any one of claims 1 to 4 is 5 to 50 [mu] m. It said optical element mounting substrate further the provided inside of the second substrate, the opto-electric hybrid board according to any one of claims 1 to 5 comprising a control element for controlling the operation of the optical element. Optoelectric according to any one of from at least a portion of the space defined between the upper surface and the second inner surface of the substrate of the first substrate claims 1 is filled with the sealing resin 6 Mixed substrate . The opto-electric hybrid board according to claim 7 , wherein the sealing resin is filled so as to cover the entire optical element. 9. The opto-electric hybrid board according to claim 1, wherein the optical element mounting substrate is laminated on one end portion or both end portions of the optical waveguide. The optical element mounting substrate is provided at one end of the optical waveguide,
The opto-electric hybrid board is provided at the other end of the optical waveguide, an opto-electric hybrid board according to any one of claims 1 to 9 comprising a connector for connecting the optical waveguide and the connection counterpart. The first substrate and the electric wiring includes a stretching portion respectively extending outwardly of the second substrate, stretched portion is bent in the middle, of the optical waveguide of the second substrate side opto-electric hybrid board according to any one of claims 1 and is configured to cover over the surface on the side opposite to that from the surface 10. Each of the first substrate and the electrical wiring includes an extended portion extending outside the second substrate,
The opto-electric hybrid board according to claim 1, further comprising a heat sink provided in the extending portion. An electronic apparatus comprising the electro-optic hybrid circuit board according to any one of claims 1 to 12.

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