JP2004294857A - Optical coupler and optical element built-in substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical coupler capable of easily optically coupling an optical element and an optical waveguide by shortening the distance between the optical element and the optical waveguide and eliminating the need for disposing a lens between both. <P>SOLUTION: The optical coupler is constituted of an optical element built-in substrate 100 in which a VCSEL (Vertical Cavity Surface Emitting Laser) 102 and a driver IC 102 and are built in and an optical waveguide substrate 110 which is integrated with an optical fiber 11 and is arranged in tight contact with the optical element built-in substrate 100. Both of the optical element built-in substrate 100 and the optical waveguide substrate 110 are planar and have approximately flat surfaces and therefore the spacing between the VCSEL 101 and a reflection mirror 112 is made as small as about 100 μm. Also, the optical element built-in substrate 100 and the optical waveguide substrate 110 are positioned by pins 120 inserted into through-holes. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical coupler and an optical element built-in substrate mainly used for relatively short distance optical transmission within a substrate, between substrates, between devices, and the like.
[0002]
[Prior art]
With the development of information communication technology and information processing technology, high speed and high density of semiconductor devices such as CPUs have been promoted, and accordingly, problems of signal delay and noise due to electric wiring have been increasing. In order to solve such a problem, a technique for coupling electronic circuits with light has been developed (for example, L. Vanassenhove, et. Al., "Demonstration of 2-D Plastic Optical Fiber based Optical Interconnect Between CMOS"). 's', OFC2001 WDD74 (Non-Patent Document 1), Journal of Japan Institute of Electronics Packaging, Vol. 5, No. 5, AUG, 2002 (Non-Patent Document 2), Real World Computing Project, Next Generation Information Processing Technology Development Business Report (Non-Patent Document 3) etc.).
[0003]
FIG. 1 is a schematic diagram illustrating an example of a conventional optical coupler. An optical waveguide 11 is formed on the main substrate 10 using an inorganic material or a polymer. At each end of the optical waveguide 11, a reflection mirror 12 is disposed at an angle of 45 ° with respect to the substrate surface, and a lens 13 is disposed above the reflection mirror 12.
[0004]
Sub-substrates 15 a and 15 b are mounted on the main substrate 10 by solder bumps 14. An LSI (Large Scale Integration) 16a in which a logic circuit is formed is mounted on the upper side of the sub-board 15a, and a VCSEL (Vertical Cavity Surface Emitting Laser: surface emitting laser) 17 and a driver are mounted on the lower side. An IC (Integrated Circuit) 18 is mounted. On the upper side of the sub-board 15b, an LSI 16b on which a logic circuit is formed is mounted, and on the lower side, a photodiode 19 and a receiver IC 20 are mounted.
[0005]
A lens 21 is arranged below the VCSEL 17 and the photodiode 19. These lenses 21 are adjusted such that their optical axes coincide with the optical axes of the lenses 13 on the main substrate 10 side.
[0006]
In the optical coupler configured as described above, the VCSEL 17 converts an electric signal input from the driver IC 18 into an optical signal and outputs the optical signal. The light output from the VCSEL 17 passes through the lenses 21 and 13 and reaches the reflection mirror 12, is reflected by the reflection mirror 12, and is introduced into the optical waveguide 11. Then, the optical signal travels in the optical waveguide 11, is reflected in the direction perpendicular to the substrate surface by the reflection mirror 12 disposed at the other end of the optical waveguide 11, passes through the lenses 13 and 21, and passes through the photodiode 19. Is transmitted to. The photodiode 19 converts the received light signal into an electric signal and outputs the electric signal to the receiver IC 20. Thus, an optical signal is transmitted from the VCSEL 17 to the photodiode 19.
[0007]
There is also an optical coupler that uses an optical fiber instead of a substrate provided with an optical waveguide and optically couples a VCSEL or a photodiode with an optical fiber.
[0008]
[Non-patent document 1]
L. Vanwassenhove, et, al. "Demonstration of 2-D Plastic Optical Fiber based Optical interconnect between CMOS IC's", OFC2001 WDD74
[Non-patent document 2]
Journal of Japan Institute of Electronics Packaging, Vol. 5, No. 5, AUG, 2002
[Non-Patent Document 3]
Real World Computing Project, Next-Generation Information Processing Technology Development Business Comprehensive Report
[0009]
[Problems to be solved by the invention]
The present inventors consider that the above-described conventional optical coupler has the following problems. That is, in the conventional optical coupler, the distance between the optical elements such as the VCSEL 17 and the photodiode 19 and the optical waveguide 11 (or the reflection mirror 12) is relatively large. 13, 21 are required. Therefore, the conventional optical coupler has a large number of components and a complicated manufacturing process.
[0010]
Further, in the conventional optical coupler, it is necessary to precisely align the optical elements such as the VCSEL 17 and the photodiode 19, the lenses 13, 21 and the reflection mirror 12, which is complicated.
[0011]
That is, a method called active alignment is usually used for these alignments. In the active alignment, the position of the lens, the reflection mirror, and the like is changed in a state where the light is output from the light source (laser), and the position where the amount of light emitted from the output side end of the optical waveguide is maximized is obtained. As described above, the active alignment requires the actual operation of the light source to perform the alignment work, and the processing is complicated.
[0012]
In view of the above, an object of the present invention is to provide an optical coupler and an optical element that can shorten the distance between an optical element and an optical waveguide and eliminate the need to provide a lens between the two, and can easily optically couple the optical element and the optical waveguide. The purpose is to provide a built-in substrate.
[0013]
[Means for Solving the Problems]
The above-described object is to provide a plate-shaped optical element built-in substrate in which an optical element is embedded, a reflection mirror and an optical waveguide, which are arranged in close contact with the optical element built-in substrate, and wherein the reflection mirror is in optical communication with the optical element. The problem is solved by an optical coupler having a coupled optical waveguide substrate.
[0014]
The distance between the optical element and the reflection mirror is preferably 100 μm or less.
[0015]
The optical element built-in substrate includes, for example, a plate-shaped substrate, an optical element built in the substrate, and a terminal formed on at least one surface of the substrate and electrically connected to the optical element. are doing.
[0016]
It is preferable that an integrated circuit connected to the optical element is incorporated in the optical element built-in substrate together with the optical element.
[0017]
The optical element built-in substrate is, for example, a core substrate on which an optical element is mounted, a reinforcing substrate in which a portion corresponding to the optical element is opened and joined to the core substrate, and filled in the opening of the reinforcing substrate. And a sealing material for sealing the optical element.
[0018]
Further, the optical element built-in substrate has a core substrate in which the optical element is mounted on a first surface and an integrated circuit mounted on a second surface, and a core substrate in which a portion corresponding to the optical element is opened. A first reinforcing substrate bonded to the first surface, a first sealing material filled in an opening of the first reinforcing substrate to seal the optical element, and a portion corresponding to an integrated circuit A second reinforcing substrate, which is opened and joined to the second surface of the core substrate, and a second sealing material that fills the opening of the second reinforcing substrate and seals the integrated circuit And may be configured by:
[0019]
When a semiconductor laser or a light receiving element formed by, for example, an ELO (epitaxial lift-off) method is used as the optical element, the thickness of the optical element built-in substrate can be set to several hundred μm to several mm.
[0020]
The optical waveguide substrate is provided with, for example, a reflection mirror arranged at 45 ° to the substrate surface, and an optical waveguide connected to the reflection mirror. The optical waveguide is composed of an optical fiber, a polymer optical waveguide film, or the like. The reflection mirror can be formed, for example, by cutting the end of the optical waveguide to form a V-groove and applying a metal film to the V-groove surface.
[0021]
An organic material for refractive index matching (refractive index matching agent) is preferably filled between the optical element built-in substrate and the optical waveguide substrate. Thereby, reflection due to a difference in the refractive index between the substrate and air can be prevented.
[0022]
Further, it is preferable to provide through holes at predetermined positions of the optical element built-in substrate and the optical waveguide substrate, respectively. Thus, the positioning of the optical element and the reflection mirror is completed only by inserting the pins into the through holes, and the active alignment step is not required. A projection may be provided on one of the optical element built-in substrate and the optical waveguide substrate, and a recess may be provided on the other. Also in this case, the positioning of the optical element and the reflection mirror is completed only by inserting the convex portion into the concave portion.
[0023]
In the present invention, an optical element such as a semiconductor laser and a photodiode is built in an optical element built-in substrate. Therefore, the surface of the substrate with built-in optical element is basically flat, and the substrate with built-in optical element and the optical waveguide substrate can be arranged in close contact. Thereby, the distance between the optical element and the reflection mirror is extremely short, for example, 100 μm or less, and the coupling loss can be reduced without using a lens.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described with reference to the accompanying drawings.
[0025]
FIG. 2 is a schematic sectional view showing an optical coupler according to an embodiment of the present invention, and FIG. 3 is an assembly diagram of the optical coupler.
[0026]
The optical coupler of the present embodiment has a thin plate-like optical element built-in substrate 100 containing a VCSEL 101 and a driver IC 102, an optical fiber 111 and a reflection mirror 112, and is disposed in close contact with the optical element built-in substrate 100. It is composed of a thin plate-shaped optical waveguide substrate 110. These optical element built-in substrate 100 and optical waveguide substrate 110 are provided with through holes 108 and 118 for alignment, and pins 120 are inserted into through holes 108 and 118 to allow the VCSEL 101 of the optical device built-in substrate 100 and the optical waveguide to be connected. The alignment with the reflection point of the reflection mirror 112 of the waveguide substrate 110 is performed.
[0027]
As shown in FIG. 2, the optical element built-in substrate 100 has a structure in which a core substrate 100a and a reinforcing substrate 100b are joined by a prepreg 105. The VCSEL 101 and the driver IC 102 are electrically connected to a conductive pattern 103 formed on the back surface of the core substrate 100a. In the present embodiment, a VCSEL 101 is a back-emitting VCSEL in which light is output to the connection terminal side (core substrate side). In the present embodiment, four VCSELs 101 are arranged side by side in a direction perpendicular to the plane of FIG. The VCSEL 101 and the driver IC 102 are arranged inside an opening provided in the reinforcing substrate 100b, and are sealed with a sealing material 104.
[0028]
A pad electrode 106 is formed on the back surface side of the optical element built-in substrate 100, and the pad electrode 106 is electrically connected to the VCSEL 101 and the driver IC 102 through the via hole 107 and the conductive pattern 103 provided in the reinforcing substrate 100b. Have been. The optical element built-in substrate 100 is connected to a main substrate (not shown), and a driving signal and driving power are supplied from the main substrate via the pad electrode 106.
[0029]
On the other hand, the optical waveguide substrate 110 includes a core substrate 110a, an optical fiber 111 disposed in a groove provided in the core substrate 110a, a reflection mirror 112 provided near an end of the optical fiber 111, and a core substrate 110a. And two reinforcing substrates 113a and 113b sandwiching the substrate from above and below. As shown in the side view of FIG. 7A and the top view of FIG. 7B, the optical fiber 111 is composed of four signal transmission optical fibers 111a and four spacer optical fibers 111b alternately. And are bundled in a tape shape.
[0030]
In the optical coupler according to the present embodiment configured as described above, the optical signal output from the VCSEL 101 passes through the core substrate 100a, reaches the optical waveguide substrate 110, is reflected by the reflection mirror 112, and is reflected in the optical fiber 111. Will be introduced.
[0031]
The thickness of each of the optical element built-in substrate 100 and the optical waveguide substrate 110 is several hundred μm to several mm. The distance between the VCSEL 101 and the reflection point of the reflection mirror 112 is 100 μm or less. Therefore, the distance between the VCSEL 101 and the reflection point of the reflection mirror 112 is extremely short, and no lens is provided between the two.
[0032]
As described above, in the present embodiment, since the distance between the VCSEL 101 and the reflection point of the reflection mirror 112 is as small as 100 μm or less, the coupling loss is small even without a lens. However, in order to further reduce the coupling loss, it is preferable to use an optical fiber 111 having a core diameter of 40 μm or more.
[0033]
Hereinafter, a method for manufacturing the optical coupler of the present embodiment will be described.
[0034]
A method for manufacturing the optical element built-in substrate 100 will be described with reference to the cross-sectional views shown in FIGS. First, as shown in FIG. 4A, an aramid film with a single-sided copper foil having a resin thickness of 47 μm (for example, Aramica of Asahi Kasei Corporation) is prepared as the core substrate 101a. Then, the copper foil is patterned by photolithography to form conductive patterns 103 such as alignment markers, pattern wiring, and pad electrodes for chip bonding.
[0035]
Next, as shown in FIG. 4B, drilling is performed with a marker as a mark by a drill or a laser to open a through hole 131 through which laser light passes in the VCSEL mounting portion. However, when the core substrate 101a has a high light-transmitting property with respect to the laser beam, the through-hole 131 may not be provided.
[0036]
Then, as shown in FIG. 4 (c), the VCSEL 101 and the driving element are formed by a PbSb-based solder, an AgSn-based solder, a CuSn-based solder, and an AuSn-based solder, or a multilayer thin film of Au / Sn, Ag / Sn, and Cu / Sn. The driver IC 102 is flip-chip mounted on the substrate 101a.
[0037]
It is preferable that the VCSEL 101 and the driver IC 102 have a small thickness. For example, a VCSEL having a thickness of about 10 μm can be formed by using a known ELO (epitaxial lift-off) method.
[0038]
Further, in the present embodiment, the VCSEL 101 and the driver IC 102 are flip-chip mounted on the substrate 101a, but the VCSEL 101 and the driver IC 102 may be mounted on the substrate 101a by TAB (Tape Automated Bonding) or wire bonding. Further, it is preferable to use the VCSEL 101 having a small spread of the output beam, but it may be selected in consideration of the operation speed and the like.
[0039]
Next, the translucent underfill 132 is filled in the through hole 131. As the translucent underfill 132, for example, JCR6122 manufactured by Dow Corning Toray Silicone Co., Ltd. can be used. In the present embodiment, since the distance from the VCSEL 101 to the reflection mirror 112 is as small as 100 μm or less, it is not necessary to require a high light transmittance for the translucent underfill 132.
[0040]
Next, as shown in FIG. 5A, a prepreg 105 having an opening at a position corresponding to the VCSEL 101 and the driver IC 102 and a reinforcing substrate 100b are prepared. The reinforcing substrate 100b is, for example, an aramid film (Aramica plate) having a thickness of 300 μm. In the present embodiment, the upper copper foil is patterned by photolithography using an aramid film in which copper foil is bonded to both sides of the reinforcing substrate 100b to form conductive patterns 135 serving as wiring and alignment markers. are doing. Note that the reinforcing substrate 100b used is thicker than the components such as the VCSEL 101 and the driver IC 102 mounted on the core substrate 100a.
[0041]
Next, as shown in FIG. 5B, the prepreg 105 is arranged between the reinforcing substrate 100b and the core substrate 100a, and the prepreg 105 joins the reinforcing substrate 100b to the core substrate 100a. Then, the sealing material 104 is filled into the opening of the reinforcing substrate 100b to seal the VCSEL 101 and the driver IC 102. Note that a material having high thermal conductivity is preferable as the sealing material. As a result, the exhaust heat of the VCSEL 101 and the driver IC 102 can be promoted.
[0042]
Thereafter, a via hole 107 is formed from the lower surface of the reinforcing substrate 100b to reach the conductor pattern 103 of the core substrate 100a by using a UV-YAG laser, and copper is deposited in the via hole 107 by copper plating. Then, the copper foil is patterned by a photolithography method to form a pad electrode 106 electrically connected to the VCSEL 101 and the driver IC 102. Then, a positioning through hole 108 penetrating from one surface to the other surface is formed at a predetermined position by a drill or a laser. Thereby, the optical element built-in substrate 100 is completed.
[0043]
Next, a method for manufacturing the optical waveguide substrate 110 will be described with reference to FIGS. First, as shown in FIG. 6A, an organic core substrate 110a having copper foils bonded on both sides is prepared. The size of the substrate 110a is, for example, 100 × 100 × 0.15 mm. As the core substrate 110a, for example, an aramid film (trade name: Aramica) with double-sided copper foil of Asahi Kasei Corporation can be used. Then, the copper foil is patterned by a photolithography method to form a marker 114 serving as a mark for alignment.
[0044]
Thereafter, using a dicer, a straight line extending to the end of the substrate having a depth of 125 μm and a width of 1 mm is placed at a predetermined position on one surface (the lower surface in FIG. 1) of the core substrate 110 a using the marker 114 as a mark. A groove 115 is formed.
[0045]
On the other hand, a quartz fiber having a core diameter of 62.5 μm and a cladding diameter of 125 μm is prepared. For example, a quartz fiber (G.62.5 / 125.3502) manufactured by Fujikura Ltd. can be used. This quartz fiber is coated and has a diameter of about 250 μm.
[0046]
Four quartz fibers are used for signal transmission, and four quartz fibers are used for spacers. The four quartz fibers for the spacer are stripped of the coating and cut to the same length as the groove 115 formed in the core substrate 110a. In addition, the coatings at the tips of the four fibers for signal transmission are peeled off.
[0047]
Then, as shown in a side view in FIG. 7 (a) and a top view in FIG. 7 (b), the optical fibers 111a for signal transmission and the fibers 111b for spacers are alternately arranged on a flat plate and fixed with an adhesive to tape. Optical fiber 111.
[0048]
Then, the tape-shaped optical fiber 111 is arranged in the groove 115 of the core substrate 110a as shown in FIG. 6B and bonded with an adhesive, so that the surface of the core substrate 110a and the surface of the tape-shaped optical fiber 111 are joined. Make them the same.
[0049]
Next, as shown in FIG. 6C, the tape-like fiber 111 is cut at a predetermined position by a dicer having a marker 114 as a mark and a blade having a cutting surface inclined at an angle of 45 °. A V-groove having a 45 ° face is formed. Next, Cr (chromium) having a thickness of 0.05 μm and Al (aluminum) having a thickness of 1 μm are sputtered in this order on the surface of the V groove to form a metal film mirror 112. After that, the V-groove is filled with the resin 116 to seal the metal film mirror 112.
[0050]
Next, as shown in FIG. 6D, reinforcing resin films 113a and 113b are bonded to the upper and lower surfaces of the core substrate 110a, respectively. The pressing conditions at the time of joining the reinforcing resin film are, for example, 180 ° C. and 120 minutes. Note that the reinforcing resin films 113a and 113b are not limited to aramid films, and for example, epoxy resin, polyphenyl ether resin (PPE), bismaleimide triazine resin (BT), or the like may be used. Further, as the reinforcing resin films 126a and 126b, for example, an aramid film with a single-sided copper foil having an insulating layer thickness of 26 μm and a copper foil thickness of 9 μm, 12 μm or 18 μm is used, and the copper foil is patterned and processed. A marker serving as a mark of time, a conductive pattern for bonding to the optical element built-in substrate 100 by solder or the like may be formed.
[0051]
Next, as shown in FIG. 6E, a positioning through hole 118 penetrating from one surface to the other surface is formed at a predetermined position by a drill or a laser. Thus, the optical waveguide substrate 110 is completed.
[0052]
After the optical device embedded substrate 100 and the optical waveguide substrate 110 are manufactured in this manner, the pins 120 are inserted into the positioning through holes 108 and 118, and the optical device embedded substrate 100 and the optical waveguide substrate 110 are overlapped. , And fixed with an adhesive or the like. At this time, it is preferable that a refractive index matching agent is filled between the optical element built-in substrate 100 and the optical waveguide substrate 110 to prevent reflection due to a difference in refractive index between the substrate and air.
[0053]
As described above, in the present embodiment, the VCSEL 101 and the driver IC 102 are mounted on the core substrate 100a, the reinforcing substrate 100b is joined to the core substrate 100a, and the sealing material 104 is filled in the opening of the reinforcing substrate 100b. Thus, the VCSEL 101 is formed. In the present embodiment, the tape-shaped optical fiber 111 is arranged in the groove 115 of the core substrate 110a, and the optical fiber 111 is integrated with the core substrate 110a. The optical device built-in substrate 100 and the optical waveguide substrate 110 thus formed have flat surfaces, and can be arranged in close contact with each other. Accordingly, the distance between the VCSEL 101 in the optical element built-in substrate 100 and the reflection point of the reflection mirror 112 of the optical waveguide substrate 110 is extremely small, 100 μm or less, and the coupling loss is reduced without providing a lens between the two.
[0054]
Further, in this embodiment, the positioning of the VCSEL 101 and the reflection point of the reflection mirror 112 is completed only by inserting the pins 108 into the through holes 108 and 118 of the optical device built-in substrate 100 and the optical waveguide substrate 110. Workability at the time of optically coupling the mirror and the reflection mirror 112 is extremely excellent.
[0055]
Furthermore, in the present embodiment, since both the optical element built-in substrate 100 and the optical waveguide substrate 110 are thin plates, handling is easy, and one or more optical element built-in substrates 100 The waveguide substrate 110 can be joined.
[0056]
In the above-described embodiment, the case where the positioning of the optical element built-in substrate 100 and the optical waveguide substrate 110 is performed by the pins 120 has been described. However, for example, as shown in FIG. A solder ball 138 is formed on the pad 137, and the solder ball 138 is inserted into the through hole 108 of the optical device built-in substrate 100 to position the optical device built-in substrate 100 and the optical waveguide substrate 110. You may do so.
[0057]
Further, in the above embodiment, the case where the VCSEL 101 and the driver IC 102 are built in the optical element built-in substrate has been described. However, as shown in FIG. 9, the photodiode 141 and the receiver IC 142 may be built. Further, the driver IC or the receiver IC may not be built in the optical device built-in substrate 100 but may be mounted on the optical device built-in substrate 100 or on the main substrate. The light receiving element can be selected from a PIN type, an MSM (Metal-Semiconductor-Metal) type, and the like.
[0058]
Further, in the above-described embodiment, the optical waveguide substrate is formed by integrating the core substrate 110a and the tape-shaped optical fiber 111. However, instead of the tape-shaped optical fiber 111, a polymer optical waveguide film is used. Is also good.
[0059]
Furthermore, in the above-described embodiment, the case has been described where the back-emitting VCSEL that outputs light to the connection terminal side (core substrate side) is used, but the surface-emitting VCSEL that outputs light to the opposite side to the connection terminal is described. It is also possible to use
[0060]
FIG. 10 is a schematic cross-sectional view showing an example of an optical element built-in substrate using a surface emitting VCSEL. The conductive pattern 156 is formed on the upper surface of the core substrate 100a, and the conductive pattern 103 is formed on the lower surface. The VCSEL 151 is mounted on the upper surface of the core substrate 100a, and the driver IC 152 is mounted on the lower surface. Further, a reinforcing substrate 100c having a VCSEL mounting portion opened is joined to the upper surface side of the core substrate 100a, and the VCSEL 151 is sealed by a translucent sealing material 153 filled in the opening of the reinforcing substrate 101c. Has been stopped.
[0061]
On the other hand, a reinforcing substrate 101b having a driver IC mounting portion opened is joined to the lower surface side of the core substrate 100a, and the driver IC 152 is sealed by a sealing material 154 filled in the opening of the reinforcing substrate 100b. Have been. A pad electrode 106 for connection to a main substrate or the like is formed on the lower surface of the reinforcing substrate 100b. The conductive pattern 106 is electrically connected to the VCSEL 151 and the driver IC 152 via contact holes provided in the reinforcing substrate 100b and the core substrate 100a.
[0062]
The same effect as in the above embodiment can be obtained in the optical element built-in substrate configured as described above.
[0063]
(Supplementary Note 1) A plate shape having an optical element built-in substrate in which an optical element is embedded, a reflection mirror and an optical waveguide, which are disposed in close contact with the optical element built-in substrate and the reflection mirror is optically coupled to the optical element. An optical coupler comprising: an optical waveguide substrate;
[0064]
(Supplementary Note 2) Both the optical element built-in substrate and the optical waveguide substrate are provided with through holes, and positioning of the optical element and the reflection point of the reflection mirror is performed by pins inserted into the through holes. 2. The optical coupler according to claim 1, wherein the operation is performed.
[0065]
(Supplementary Note 3) One of the optical element built-in substrate and the optical waveguide substrate has a concave portion, and the other substrate has a convex portion, and the convex portion is inserted into the concave portion, and 2. The optical coupler according to claim 1, wherein positioning between an optical element and a reflection point of the reflection mirror is performed.
[0066]
(Supplementary Note 4) The optical coupling element according to Supplementary Note 1, wherein the reflection mirror is formed on a surface obtained by diagonally cutting the optical waveguide.
[0067]
(Supplementary Note 5) It has a plate-like substrate, an optical element incorporated in the substrate, and a terminal formed on at least one surface of the substrate and electrically connected to the optical element. Optical element built-in substrate.
[0068]
(Supplementary Note 6) The plate-shaped substrate includes a core substrate on which the optical element is mounted, a reinforcing substrate having a portion corresponding to the optical element opened and connected to the core substrate, and a reinforcing substrate. 6. The optical element built-in substrate according to claim 5, further comprising a sealing material filled in the opening to seal the optical element.
[0069]
(Supplementary Note 7) The substrate with a built-in optical element according to Supplementary Note 5, wherein an integrated circuit connected to the optical element is built in the substrate.
[0070]
(Supplementary Note 8) The plate-shaped substrate may include a core substrate on which the optical element is mounted on a first surface, a core substrate on which the integrated circuit is mounted on a second surface, and an opening corresponding to the optical element. A first reinforcing substrate bonded to a first surface of the core substrate, a first sealing material that fills an opening of the first reinforcing substrate and seals the optical element; A second reinforcing substrate having an opening corresponding to an integrated circuit and joined to the second surface of the core substrate; and filling the opening in the second reinforcing substrate to seal the integrated circuit 8. The optical element built-in substrate according to claim 7, comprising a second sealing material.
[0071]
(Supplementary note 9) The optical element built-in substrate according to Supplementary note 5, wherein the substrate is provided with a hole through which light input / output to / from the optical element passes.
[0072]
(Supplementary Note 10) A first step of preparing a core substrate having a copper foil bonded to at least one surface, a second step of etching a copper foil of the core substrate to form a conductive pattern, A third step of mounting an optical element on one surface, a fourth step of joining a reinforcing substrate provided with an opening corresponding to the optical element to one surface of the core substrate, And f. Sealing the optical element by filling the opening with a sealing material.
[0073]
(Supplementary Note 11) The optical device-embedded substrate according to Supplementary Note 10, further comprising, before the third step, an opening in the core substrate through which light input / output to / from the optical element passes. Production method.
[0074]
(Supplementary note 12) The substrate with a built-in optical element according to Supplementary note 10, further comprising a step of forming a through hole from the other surface of the reinforcing substrate to the conductive pattern of the core substrate after the fifth step. Manufacturing method.
[0075]
(Supplementary note 13) The method for manufacturing a substrate with a built-in optical element according to supplementary note 10, wherein at least one of the conductive patterns is used as a positioning marker.
[0076]
【The invention's effect】
As described above, according to the present invention, since the optical element is built in the optical element built-in substrate, the distance between the optical element of the optical element built-in substrate and the reflection point of the reflection mirror of the optical waveguide substrate is 100 μm or less. Can be Thereby, the coupling loss can be reduced without providing a lens between the optical element and the reflection mirror, and the manufacturing cost can be reduced.
[0077]
Also, for example, if a through hole is provided at a predetermined position on both the optical element built-in substrate and the optical waveguide substrate, the positioning of the optical element built-in substrate and the optical waveguide substrate can be performed by inserting a pin into the through hole. Complete. Therefore, active alignment is not required, and the optical element built-in substrate and the optical waveguide substrate can be easily optically coupled.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating an example of a conventional optical coupler.
FIG. 2 is a schematic cross-sectional view illustrating an optical coupler according to an embodiment of the present invention.
FIG. 3 is an assembly view of the optical coupler of the embodiment.
FIG. 4 is a cross-sectional view (part 1) illustrating the method for manufacturing the optical element-embedded substrate.
FIG. 5 is a sectional view (part 2) illustrating the method for manufacturing the optical-element built-in substrate.
FIG. 6 is a cross-sectional view illustrating the method of manufacturing the optical waveguide substrate.
FIG. 7A is a side view of a tape-shaped optical fiber, and FIG. 7B is a top view of the same.
FIG. 8 is a schematic cross-sectional view showing an optical coupler for performing alignment between an optical element built-in substrate and an optical waveguide substrate using through holes and solder balls.
FIG. 9 is a schematic cross-sectional view showing an optical element built-in substrate including a photodiode and a receiver IC.
FIG. 10 is a schematic cross-sectional view showing an example of an optical element built-in substrate using a surface-emitting VCSEL.
[Explanation of symbols]
10 ... Main board,
11 ... optical waveguide,
12, 112 ... reflection mirror,
13, 21 ... lens,
14 solder bumps
15a, 15b: Sub-substrate,
16a, 16b ... LSI,
17, 101, 151 ... VCSEL,
18, 102, 152 ... driver IC,
19,141 ... photodiode,
20, 142 ... receiver IC,
100 ... optical element built-in substrate,
100a, 110a ... core substrate,
100b, 113a, 113b ... reinforcing substrate,
103, 135, 156 ... conductive pattern,
104, 153, 154 ... sealing material,
105 ... prepreg,
106 ... pad electrode,
107 ... via hole,
108, 118, 131 ... through-hole,
110 ... optical waveguide substrate,
111 ... optical fiber,
114 ... marker,
115 ... groove,
120 ... pin,
132 ... underfill,
138: Solder ball.

Claims (5)

An optical element built-in substrate in which the optical element is embedded,
An optical coupler comprising: a reflecting mirror and an optical waveguide; and a plate-shaped optical waveguide substrate disposed in close contact with the optical element built-in substrate and wherein the reflecting mirror is optically coupled to the optical element. A plate-like substrate,
An optical element built in the substrate,
And a terminal formed on at least one surface of the substrate and electrically connected to the optical element. The plate-shaped substrate,
A core substrate on which the optical element is mounted,
A reinforcing substrate having a portion corresponding to the optical element opened and connected to the core substrate,
The optical element built-in substrate according to claim 2, further comprising: a sealing material that fills an opening of the reinforcing substrate and seals the optical element. 4. The optical element built-in substrate according to claim 3, wherein an integrated circuit connected to the optical element is built in the substrate. The plate-shaped substrate,
A core substrate on which the optical element is mounted on a first surface and the integrated circuit is mounted on a second surface;
A first reinforcing substrate having an opening corresponding to the optical element and joined to a first surface of the core substrate;
A first sealing material filled in the opening of the first reinforcing substrate to seal the optical element;
A second reinforcing substrate having a portion corresponding to the integrated circuit opened and joined to a second surface of the core substrate;
5. The optical element built-in substrate according to claim 4, further comprising a second sealing material that fills an opening of the second reinforcing substrate and seals the integrated circuit. 6.

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