JP4337918B2 - Optoelectronic circuit board - Google Patents

Description

  The present invention relates to an optoelectronic circuit board.

  Optical communication technology using light as an information transmission medium has become widespread. In such an optical communication technology, an optical integrated circuit in which an optical waveguide is disposed on a substrate has been proposed in order to transmit an optical signal obtained by modulating light with a signal indicating information (see, for example, Patent Document 1). ).

  This optical integrated circuit includes a mounting substrate, four surface emitting semiconductor laser elements disposed on one side of the mounting substrate, four photodiodes disposed on the other side of the mounting substrate, and a surface emitting semiconductor. An optical waveguide disposed on the laser element and the photodiode and having a reflection surface inclined at an angle of 45 degrees at a position facing the surface emitting semiconductor laser element and the photodiode. The optical waveguide has a structure in which four cores are covered with a clad having a refractive index smaller than that of the core, and a silicon substrate is formed on the upper surface.

The optical signals emitted from the four surface emitting semiconductor laser elements are reflected by one reflection surface of the optical waveguide, propagated while totally reflecting in the corresponding core, and reflected by the other reflection surface of the optical waveguide. It enters each of the four photodiodes.
JP 2004-302401 A

  An object of the present invention is to provide an optoelectronic circuit board in which a defective portion can be easily identified.

  To achieve the above object, the present invention provides the following optoelectronic circuit board.

[1] A substrate having an inspection opening, a clad formed around the core, provided on one surface side of the substrate, exposed to the inspection opening of the substrate, and on the inspection opening side An optoelectronic circuit board comprising: an optical waveguide having a curved portion; and a core exposed surface formed so that the core is exposed from the clad in the curved portion of the optical waveguide.

[2] A light emitting side opening that allows an optical signal to pass from the first surface side to the second surface side, a light receiving side opening that allows the optical signal to pass from the second surface side to the first surface side, and A substrate on which an inspection opening located between the light emitting side opening and the light receiving side opening is formed; and mounted on the first surface side of the substrate and provided at a position facing the light emitting side opening. A light-emitting element that emits an optical signal, a light-receiving element that is provided at a position facing the light-receiving-side opening, and that receives the optical signal, and a clad is formed around the core so that the second surface side of the substrate A first optical path conversion surface that converts the optical path of the optical signal that passes through the light emitting side opening from the first surface side to the second surface side, and is converted by the first optical path conversion surface. The optical signal passes through the light receiving side opening from the second surface side to the first surface side. An optical waveguide having a second optical path conversion surface for converting the optical path of the optical signal, a portion exposed to the inspection opening of the substrate and curved toward the inspection opening, and the optical waveguide An optoelectronic circuit board comprising: a core exposed surface formed so that the core is exposed from the clad at the curved portion.

[3] The optoelectronic circuit board according to [1] or [2], further including a sealing resin having a refractive index smaller than that of the core and covering the exposed core surface of the optical waveguide.

[4] The optoelectronic circuit board according to [1] or [2], further including another substrate disposed on the substrate via the optical waveguide.

  According to the optoelectronic circuit board according to the first aspect, it is easy to identify a defective portion.

  According to the optoelectronic circuit board of the second aspect, it is easy to identify whether the defective portion is the light emitting element, the light receiving element, or the optical waveguide while the light emitting element and the light receiving element are mounted.

  According to the optoelectronic circuit board according to the third aspect, optical signal leakage from the exposed core surface is reduced, and transmission loss can be reduced.

  According to the optoelectronic circuit board of the fourth aspect, the mounting density of electronic components and the like mounted on the board can be increased.

[First Embodiment]
1A and 1B show a schematic configuration of an optoelectronic circuit board according to a first embodiment of the present invention. FIG. 1A is a perspective view, and FIG. 1B is a cross-sectional view taken along line AA in FIG. .

  The optoelectronic circuit board 1 is a combination of an optical circuit and an electronic circuit, and is configured by embedding an optical waveguide 13 (see FIG. 1B) in a printed board 100.

  The printed circuit board 100 includes first and second substrates 10 and 11 disposed via an optical waveguide 13, and the first and second optical modules are formed on the upper surface (first surface) of the first substrate 10. 12A and 12B are mounted, and these optical modules 12A and 12B are optically connected to the optical waveguide 13. Note that the number of substrates (number of layers) having wiring in the printed circuit board 100 is not limited to two, and may be three or more.

  The first optical module 12A includes a light emitting element array 120 in which a plurality of light emitting elements 120a are arranged as an example, a drive circuit that drives the light emitting elements 120a, and the like. The second optical module 12B includes a light emitting element array 121 in which a plurality of light receiving elements 121a are arranged in a line, an amplifier circuit that amplifies an output signal from the light receiving element 121a, and the like. The first and second optical modules 12A and 12B are packaged, and their detailed configurations will be described later.

(First substrate)
For example, the first substrate 10 is formed on a base material made of an insulating material such as a glass epoxy resin having a thickness of 0.5 mm, and an upper surface of the base material, and various electronic components, power circuit components, etc. An electrically connected conductive pattern.

  Further, as shown in FIG. 1A, the first substrate 10 has an inspection opening 14 with a through hole for inputting / outputting inspection light to / from the optical waveguide. The inspection opening 14 is filled with a clad material filling portion 15 after the inspection is completed. The opening diameter of the inspection opening 14 has a size that allows the later-described curved portion of the optical waveguide 13 to be exposed, for example, 5 × 5 mm.

  The clad filling portion 15 is made of a resin having the same refractive index as that of the clad 132 of the optical waveguide 13.

(Second substrate)
The second substrate 11 is formed on, for example, a base material made of an insulating material such as a glass epoxy resin having a thickness of 1 mm, and a lower surface of the base material. Various electronic components, power circuit components, and the like are electrically used. And a protrusion 17 made of synthetic resin or the like at a position facing the inspection opening 14 on the upper surface of the base material. The protrusion 17 has a trapezoidal cross section, but may have another shape such as a semicircular shape.

(Optical waveguide)
As shown in FIG. 1B, the optical waveguide 13 has, for example, four cores 131 having an overall thickness of 0.2 mm and a rectangular cross section of 50 × 50 μm, and around these cores 131. The clad 132 is formed and has a refractive index smaller than that of the core 131.

  2 shows an outline of the optoelectronic circuit board according to the first embodiment of the present invention. FIG. 2 (a) is a cross-sectional view taken along the line BB of FIG. 1 (a), and FIG. It is the C section detail drawing of Fig.2 (a).

(First optical module)
The first optical module 12A includes a relay board 129, the above-described light emitting element array 120 mounted on the lower surface of the relay board 129, and a control unit 127A mounted on the upper surface of the relay board 129.

  The relay substrate 129 has a base material made of an insulating material, and pads 123 and terminals 124 are formed on the base material. The terminal 124 is electrically connected to the terminal 110 of the first substrate 10 by a solder ball (conductive ball) 125 such as a BGA (Ball Grid Array).

  The control unit 127A includes a drive circuit that drives the four light emitting elements 120a, is bonded to the relay substrate 129 with an adhesive, is connected to the terminal 124 with a wire 126, and is entirely sealed with a sealing resin 128 such as an epoxy resin. It has been stopped.

  A space between the light emitting element array 120 and the optical waveguide 13 is sealed with an optical resin 16 having the same refractive index as that of the clad 132.

  The light emitting element 120a of the light emitting element array 120 uses a surface light emitting element having a mounting surface on the side opposite to the light output surface (optical surface) for outputting an optical signal. As the surface light emitting element, for example, a surface light emitting diode or a surface emitting laser can be used. In this embodiment, a surface emitting laser is used. A surface emitting laser array using this surface emitting laser has, for example, an n-type lower reflector layer, an active layer, a current confinement layer, a p-type upper reflector layer, a p-type contact layer, and a p-side on an n-type GaAs substrate. An electrode is formed, and an n-side electrode is formed on the back surface of the n-type GaAs substrate. The active layer, the current confinement layer, the p-type upper reflector layer, the p-type contact layer, and the p-side electrode are formed of the light emitting element 120a. It is formed every time and is electrically connected to the pad 123 of the relay substrate 129 by a wire 122.

(Second optical module)
The second optical module 12B includes a relay substrate 129 similar to the first optical module 12A, the above-described light receiving element array 121 mounted on the lower surface of the relay substrate 129, and a control unit mounted on the upper surface of the relay substrate 129. 127B.

  The control unit 127B includes an amplifier circuit that amplifies the electrical signals output from the four light receiving elements 121a and a signal processing circuit that converts the output signals of the amplifier circuits into image signals and the like, and is bonded to the relay substrate 129 with an adhesive. The wire 126 is connected to the terminal 124, and the whole is sealed with a sealing resin 128 such as an epoxy resin.

  The light receiving element 121a of the light receiving element array 121 uses a surface light receiving element having a mounting surface on the opposite side to the light input surface (optical surface) for inputting an optical signal. As the surface light receiving element, for example, a surface photodiode can be used. In this embodiment, a GaAs PIN photodiode having excellent high-speed response is used. The light receiving element array 121 using the PIN photodiode is formed, for example, on a GaAs substrate on a P-layer, I-layer, and N-layer that are PIN-bonded, a p-side electrode connected to the P-layer, and an N-layer. The P layer, the I layer, the N layer, the p side electrode, and the n side electrode are formed for each light receiving element 121a and are electrically connected to the pad 123 of the relay substrate 129 by the wire 122. Yes.

  The space between the light receiving element array 121 and the optical waveguide 13 is sealed with an optical resin 16 having the same refractive index as that of the clad 132.

(First substrate)
The first substrate 10 has four light emitting side openings 10a formed at positions facing the four light emitting elements 120a, and four light receiving side openings 10b formed at positions respectively opposed to the four light receiving elements 121a. . The four light emitting side openings 10a and the four light receiving side openings 10b may be one common opening.

(Optical waveguide)
The optical waveguide 13 has a curved portion 13a that is exposed to the inspection opening 14 side along the protrusion 17 and is curved to the inspection opening 14 side, and the core 131 is exposed from the clad 132 to the curved portion 13a. Thus, a core exposed surface 134 is formed.

(Optical circuit board manufacturing method and inspection method)
Next, an example of an optoelectronic circuit board manufacturing method and inspection method will be described. The inspection of the optoelectronic circuit board is performed in the process of manufacturing the optoelectronic circuit board.

(1) Fabrication of optical waveguide First, a fabrication example of the optical waveguide 13 will be described. The optical waveguide 13 can be manufactured by, for example, a commonly used photolithography method or a method using RIE (reactive ion etching). In particular, it can be efficiently produced by a production process using a mold described in Japanese Patent Application Laid-Open No. 2004-29507 already proposed by the present applicant. The manufacturing process will be described below.

  First, a master on which convex portions corresponding to the four cores 131 are formed is produced using, for example, a photolithography method. Next, a curable resin having a viscosity of, for example, about 500 to 7000 mPa · s and having light transmittance in the ultraviolet region and the visible region, for example, a methylsiloxane group in the molecule, A layer of curable organopolysiloxane containing an ethylsiloxane group and a phenylsiloxane group is provided by coating or the like, and then cured to form a cured layer. Next, the hardened layer is peeled from the master, and a mold having a concave portion corresponding to the convex portion is produced.

  Next, a clad film substrate made of a resin excellent in adhesion to the mold, for example, an alicyclic acrylic resin film, an alicyclic olefin resin film, a cellulose triacetate film, a fluororesin film, or the like is adhered to the mold. Let Next, the concave portion of the mold is filled with, for example, an ultraviolet curable or thermosetting monomer, an oligomer or a mixture of a monomer and an oligomer, an epoxy type, a polyimide type, an acrylic type ultraviolet curable resin, or the like. . Next, the curable resin in the recess is cured to form the core 131, and then the mold is peeled off. As a result, the four cores 131 are left on the clad film substrate.

  Next, the clad 132 is provided so as to cover the core 131 on the surface side of the clad film substrate on which the core 131 is formed. Examples of the clad 132 include a film, a layer obtained by applying and curing a clad curable resin, and a polymer film obtained by applying and drying a solvent solution of a polymer material.

  Finally, the surface where the core 131 of the optical waveguide is exposed is cut at a predetermined angle by a dicer to form an optical path conversion surface. Further, by cutting with a dicer parallel to the core 131, the optical waveguide 13 having the clad film base material and the clad layer as the clad 132 is completed.

  Next, the optical waveguide 13 is disposed on the second substrate 11. At this time, the optical waveguide 13 is formed with a curved portion 13 a that is curved along the protrusion 17 on the second substrate 11. As shown in FIG. 2B, the portion of the clad 132 of the curved portion 13a is removed by cutting, polishing, or the like to form a core exposed portion 134 where the core 131 is exposed.

  Next, the first substrate 10 is disposed on the optical waveguide 13 disposed on the second substrate 11, and the first and second optical modules 12A and 12B and other necessary electrons are disposed on the first substrate 10. Mount components, power supply components, etc.

(2) Inspection of Optoelectronic Circuit Board FIG. 3 is a cross-sectional view corresponding to the cross section taken along the line BB of FIG. 1A, showing a state of inspection on the first optical module 12A side.

  First, the optical signal 2 is output from each of the four light emitting elements 120a of the light emitting element array 120 of the first optical module 12A. The output optical signal 2 passes through the light emission side opening 10 a, is converted in optical path by the optical path conversion surface 133 A, and propagates through the core 131 of the optical waveguide 13.

  A part of the optical signal 2 propagated through each of the four cores 131 is output to the outside as the inspection light 2 a from the core exposed surface 134. The inspection light 2a is received by, for example, a light receiving inspection unit 18A composed of four photodiodes. At this time, the light reception inspection unit 18A is rotated around the bending portion 13a, and the maximum output value is detected from each of the four photodiodes of the light reception inspection unit 18A.

  When the four inspection lights 2a can be detected with an appropriate amount of light by the light receiving inspection section 18A, it can be seen that the first optical module 12A side is operating normally. After the inspection, the inspection opening 14 is sealed with the clad material filling portion 15.

  When the number of inspection lights 2a detected by the light-receiving inspection unit 18A with an appropriate amount of light is three or less, the corresponding light-emitting element 120a of the first optical module 12A is malfunctioning or the light-emitting element array 120 side of the optical waveguide 13 It can be seen that dust or the like adheres to the optical path conversion surface 133A side of the optical path and that the optical path is defective.

  FIG. 4 is a cross-sectional view corresponding to the cross section taken along line B-B in FIG. 1A, showing a state of inspection on the second optical module 12 </ b> B side.

  First, four inspection lights 2b are incident on the core exposed surface 134 from the light emission inspection unit 18B including four light emitting elements. At this time, the light emission inspection unit 18B is rotated around the curved portion 13a so that the detection light 2b having the maximum light intensity enters the core exposed surface 134 from the four light emitting elements of the light emission inspection unit 18B. The inspection light 2b enters the four cores 131 from the core exposed surface 134, and propagates the core 131 to the second optical module 12B side. The inspection light 2b that has propagated through the core 131 has its optical path converted by the optical path conversion surface 133B, and is received by the four light receiving elements 121a of the light receiving element array 121 of the second optical module 12B. The light receiving element 121a converts the received inspection light 2b into an electrical signal and outputs it.

  When the four detection lights 2b can be detected with appropriate light amounts by the light receiving element array 121, it can be seen that the second optical module 12B side is operating normally. After the inspection, the inspection opening 14 is sealed with the clad material filling portion 15.

  When the number of inspection lights 2b detected by the light receiving element array 121 with an appropriate amount of light is three or less, the corresponding light receiving element 121a of the second optical module 12B is malfunctioning or the light receiving element array 121 side of the optical waveguide 13 It can be seen that dust or the like adheres to the optical path conversion surface 133B side of the optical path and that the optical path is defective.

(Operation of optoelectronic circuit board)
The operation of the optoelectronic circuit board 1 will be described below with reference to FIGS.

(1) Transmission / Reception of Optical Signal Here, as an example, a case where an image signal is transmitted from the first optical module 12A to the second optical module 12B will be described. The drive circuit of the control unit 127A of the first optical module 12A transmits a drive signal to the light emitting element 120a of the light emitting element array 120 based on the image signal. The light emitting element 120a transmits the optical signal 2 toward the optical path conversion surface 133A of the optical waveguide 3 through the light emission side opening 10a based on the drive signal. At this time, the voltage of the drive signal is applied between the p-type electrode and the n-type electrode of the light emitting element 120a, and for example, laser light having a wavelength of 850 nm is output as the optical signal 2 from the light emitting region of the light emitting layer.

  The optical path conversion surface 133A converts the optical path of the optical signal 2 transmitted from the light emitting element 120a, and propagates the optical signal 2 to the core 131 of the optical waveguide 13. The optical signal 2 propagated to the core 131 is converted by the optical path conversion surface 133B, passes through the light receiving side opening 10b, and is received by the light receiving element array 121 of the second optical module 12B. The light receiving element 121a converts the received optical signal 2 into an electrical signal and outputs it to the control unit 127B.

  The amplifier circuit of the control unit 127B amplifies the converted electric signal, and the signal processing circuit processes the signal from the amplifier circuit to generate an image signal, and generates a predetermined signal on the first or second substrate 10 or 11. Output to the electronic component.

[Second Embodiment]
FIG. 5 shows a schematic configuration of the optoelectronic circuit board according to the second embodiment of the present invention, and is a cross-sectional view corresponding to a cross section taken along line BB of FIG.

  In the first embodiment, the inspection is performed on the first substrate 10 side, but in the present embodiment, the inspection is performed on the second substrate 11 side.

  The first substrate 10 has a light emitting side opening 10a and a light receiving side opening 10b formed at positions facing the light emitting element 120a and the light receiving element 121a, respectively, but no inspection opening is formed. The second substrate 11 has an inspection opening 14 formed therein. A protrusion 17 is provided on the lower surface of the first substrate 10 at a position corresponding to the inspection opening 14.

  The optical waveguide 13 is exposed to the inspection opening 14 formed in the second substrate 11 along the protrusion 17 provided on the first substrate 10 side, and is curved to the inspection opening 14. A core exposed surface 134 is formed on the curved portion 13 a so that the core 131 is exposed from the clad 132.

  Also in the second embodiment, similarly to the first embodiment, the first optical module 12A and the second light are input and output by inputting and outputting the inspection lights 2a and 2b to the core exposed surface 134. The module 12B, the optical path conversion surfaces 133A and 133B of the optical waveguide 13 can be inspected for abnormalities. Since the inspection method of the optoelectronic circuit board 1 is the same as that of the first embodiment, the description thereof is omitted.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

1A and 1B show a schematic configuration of an optoelectronic circuit board according to a first embodiment of the present invention. FIG. 1A is a perspective view, and FIG. 1B is a cross-sectional view taken along line AA in FIG. . 2A is a cross-sectional view taken along line BB in FIG. 1A, and FIG. 2B is a detailed view of a portion C in FIG. 2A. FIG. 3 is a cross-sectional view corresponding to the cross section taken along line B-B of FIG. 1A, showing a state of inspection on the first optical module side according to the first embodiment of the present invention. FIG. 4 is a cross-sectional view corresponding to a cross section taken along line BB in FIG. 1A, showing a state of inspection on the second optical module side according to the first embodiment of the present invention. FIG. 5 shows a schematic configuration of the optoelectronic circuit board according to the second embodiment of the present invention, and is a cross-sectional view corresponding to a cross section taken along line BB of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Optoelectronic circuit board, 2 ... Optical signal, 2a, 2b ... Inspection light, 10 ... 1st board | substrate, 10a ... Light emission side opening, 10b ... Light reception side opening, 11 ... 2nd board | substrate, 12A ... 1st light Module, 12B ... second optical module, 13 ... optical waveguide, 13a ... curved portion, 14 ... inspection opening, 15 ... clad material filling portion, 16 ... optical resin, 17 ... projection, 18A ... light receiving inspection portion, 18B DESCRIPTION OF SYMBOLS ... Light emission test | inspection part, 10a ... Light emission side opening, 10b ... Light reception side opening, 100 ... Printed circuit board, 110 ... Terminal, 120 ... Light emitting element array, 120a ... Light emitting element, 121 ... Light receiving element array, 121a ... Light receiving element, 122 ... Wire, 123 ... Pad, 124 ... Terminal, 125 ... Solder ball, 126 ... Wire, 127A ... Control part, 127B ... Control part, 128 ... Sealing resin, 129 ... Relay board, 131 ... Core, 13 ... cladding, 133A ... optical path changing surface, 133B ... optical path changing surface, 134 ... core exposed surface

Claims (4)

A substrate having an inspection opening;
An optical waveguide having a portion that is formed around the core and is provided on one side of the substrate, exposed to the inspection opening of the substrate, and curved toward the inspection opening;
An optoelectronic circuit board comprising: a core exposed surface formed so that the core is exposed from the clad in the curved portion of the optical waveguide. A light emitting side opening for allowing an optical signal to pass from the first surface side to the second surface side, a light receiving side opening for allowing the optical signal to pass from the second surface side to the first surface side, and the light emitting side opening. And a substrate on which an inspection opening located between the light receiving side opening and the substrate is formed,
A light emitting element mounted on the first surface side of the substrate and provided at a position facing the light emitting side opening to emit the optical signal, and a light emitting element provided at a position facing the light receiving side opening. A light receiving element for receiving light;
A clad is formed around the core, provided on the second surface side of the substrate, and converts an optical path of the optical signal passing through the light emitting side opening from the first surface side to the second surface side. The first optical path conversion surface, and the optical signal converted by the first optical path conversion surface passes through the light receiving side opening from the second surface side to the first surface side of the optical signal. A second optical path conversion surface for converting an optical path, and an optical waveguide having a portion exposed to the inspection opening of the substrate and curved toward the inspection opening;
An optoelectronic circuit board comprising: a core exposed surface formed so that the core is exposed from the clad in the curved portion of the optical waveguide.   The optoelectronic circuit board according to claim 1, further comprising a sealing resin having a refractive index smaller than that of the core and covering the exposed core surface of the optical waveguide.   The optoelectronic circuit board according to claim 1, further comprising another board disposed on the board via the optical waveguide.

Images