JP5300700B2 - Optical wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical waveguide member meeting a request for improving a signal transmission characteristic. <P>SOLUTION: The optical waveguide member 6 includes a first clad layer 15a, a second clad layer 15b stacked on the top surface of the first clad layer 15a, and a core layer 16 that is surrounded with the first clad layer 15a and second clad layer 15b and has refractive index higher than those of the first clad layer 15a and second clad layer 15b. The core layer 16 includes: a lower surface having a first abutting surface 16a1 surface-abutting on the top surface of the first clad layer 15a; a top surface that surface-abuts on the second clad layer 16a2 and has a second abutting surface 16a2 at least partially overlapping the first abutting surface 16a1 in plan view; and a side surface having a projection part 16b projecting toward the outside of the first abutting surface 16a1 and the second abutting surface 16a2. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an optical waveguide member used for electronic equipment (for example, various audiovisual equipment, home appliances, communication equipment, computer equipment and peripheral equipment).

  In recent years, an optical wiring module including an optical semiconductor element and an optical wiring substrate is sometimes used for an electronic device. The optical wiring board includes an optical waveguide member that transmits an optical signal as a part of the wiring.

  Patent Document 1 is surrounded by a lower cladding layer (first cladding layer), an upper cladding layer (second cladding layer) laminated on the upper surface of the lower cladding layer, the lower cladding layer and the upper cladding layer, An optical waveguide member including a lower cladding layer and a core layer having a higher refractive index than the upper cladding layer, wherein the core layer has a rectangular cross section orthogonal to the longitudinal direction.

  By the way, the optical signal travels along the longitudinal direction in the core layer while being repeatedly reflected at the interface between the core layer and the clad layer. Therefore, if the core layer has a rectangular shape in a cross section perpendicular to the longitudinal direction, the length of the diagonal line in the cross section is larger than the distance between the upper and lower surfaces, and therefore the travel distance varies depending on the travel path of the optical signal, A phase difference occurs between optical signals having different traveling paths, the optical signals are attenuated, and the signal transmission characteristics of the optical waveguide member are likely to deteriorate.

JP 2003-161853 A

The present invention provides an optical wiring board that meets the demand for improving signal transmission characteristics.

An optical wiring board according to an aspect of the present invention includes a wiring board having a plurality of conductive layers and a resin layer that insulates the conductive layers, a first cladding layer disposed on the wiring board, and the first cladding. A second clad layer laminated on the upper surface of the layer, and a core layer surrounded by the first and second clad layers and having a refractive index higher than that of the first and second clad layers, the core layer comprising: A lower surface having a first contact surface that is in surface contact with the upper surface of the first cladding layer, and a second contact that is in surface contact with the second cladding layer and at least partially overlaps the first contact surface in plan view. a top surface having a surface, than the first and second than abutment surface possess a side having a protrusion protruding outwardly, and the first width of the contact surface is the second abutment surface greater, the core layer is to be superimposed in plan view on the conductive layer of the uppermost layer of the wiring substrate And butterflies.

According to the optical wiring board of one embodiment of the present invention, since the core layer has protrusions, the width of the upper surface and the lower surface of the core layer can be reduced. Thus, the length of the diagonal line can be shortened, and the difference in length between the diagonal line and the distance between the upper and lower surfaces can be reduced. Therefore, an optical wiring board having excellent signal transmission characteristics can be obtained by reducing the difference in travel distance that varies depending on the travel path of the optical signal.

Fig.1 (a) is sectional drawing parallel to the longitudinal direction of the core layer which cut | disconnected the optical wiring module concerning one Embodiment of this invention in the thickness direction, FIG.1 (b) is FIG.1 (a). It is sectional drawing which expanded and showed R1 part of the optical wiring module shown in FIG. 2A is a cross-sectional view perpendicular to the longitudinal direction of the core layer, taken along line I-I of FIG. 2A, and FIG. 2B is a cross-sectional view of FIG. It is sectional drawing parallel to the plane direction which cut | disconnected along the -II line | wire and saw through the core layer. 3A and 3B are cross-sectional views cut in the thickness direction for explaining the manufacturing process of the optical wiring module shown in FIG. 4A is a cross-sectional view cut in the thickness direction for explaining a manufacturing process of the optical wiring module shown in FIG. 1A, and FIG. 4B is an optical wiring module shown in FIG. It is sectional drawing which expanded and showed R1 part explaining the manufacturing process of this. FIGS. 5A and 5B are cross-sectional views taken along the line III-III for explaining the manufacturing process of the optical wiring module shown in FIG. 1A. FIG. 6A is a cross-sectional view taken along the line III-III in FIG. 4B for explaining the manufacturing process of the optical wiring module shown in FIG. 1A. FIG. FIG. 2 is a cross-sectional view taken along the thickness direction for explaining a manufacturing process of the optical wiring module shown in FIG. 7A and 7B are cross-sectional views cut in the thickness direction for explaining the manufacturing process of the optical wiring module shown in FIG. It is sectional drawing of the part corresponding to FIG. 2 (a) of the optical wiring module concerning other one Embodiment of this invention.

  Hereinafter, an optical wiring module including an optical waveguide member according to an embodiment of the present invention will be described in detail based on the drawings.

  The optical wiring module 1 shown in FIG. 1A is used for electronic devices such as various audiovisual devices, home appliances, communication devices, computer devices or peripheral devices thereof. The optical wiring module 1 includes an optical semiconductor element 2 and an optical wiring substrate 3 on which the optical semiconductor element 2 is mounted.

  The optical semiconductor element 2 functions as a light emitting element or a light receiving element, for example, and is flip-chip mounted on the upper surface of the optical wiring board 3 via bumps 4 containing a conductive material such as solder. It is electrically connected to the wiring board 3. The light emitting element converts an electrical signal supplied from the optical wiring board 3 into an optical signal and supplies the optical signal to the optical wiring board 3. For example, a surface emitting semiconductor laser or the like can be used. The light receiving element converts an optical signal supplied from the optical wiring board 3 into an electric signal and supplies the electric signal to the optical wiring board 3. For example, a photodiode or the like can be used. As this optical semiconductor element 2, a base material made of a semiconductor material such as silicon, and an average thickness, that is, an average thickness set to, for example, 0.1 mm or more and 1 mm or less can be used. .

  The optical wiring board 3 includes a wiring board 5 and an optical waveguide member 6 formed on the upper surface of the wiring board 5.

  The wiring board 5 transmits an electrical signal while increasing the rigidity of the optical wiring board 3, and includes a core substrate 7 and a pair of wiring layers 8 formed on the upper and lower surfaces of the core substrate 7.

  The core substrate 7 is intended to increase the rigidity of the wiring substrate 5 while achieving conduction between the pair of wiring layers 8 and has an average thickness of 0.1 mm to 3.0 mm, for example. The core substrate 7 includes a base 9, a through-hole conductor 10 and an insulator 11.

  The base 9 increases the rigidity of the core substrate 7 and includes, for example, a resin material and a base material coated with the resin material. As this resin material, for example, an epoxy resin or a polyimide resin can be used. Moreover, as a base material, what arranged the woven fabric or the nonwoven fabric comprised by glass fiber, carbon fiber, etc. or the fiber in one direction can be used. The substrate 9 preferably contains an inorganic insulating filler formed of an inorganic insulating material such as silicon oxide or silicon nitride.

  The through-hole conductor 10 electrically connects the pair of wiring layers 8, includes a conductive material such as copper, and extends along the inner wall of the cylindrical through-hole that penetrates the base 9 in the thickness direction (Z direction). It is formed in a cylindrical shape. An insulator 11 containing a resin material such as an epoxy resin is formed in a columnar shape in the hollow portion of the through-hole conductor 8 formed in a cylindrical shape.

  The wiring layer 8 increases the electric wiring density of the wiring substrate 5, and includes a resin layer 12, a conductive layer 13, and a via conductor 14. The conductive layer 13 and the via conductor 14 are electrically connected to each other, and constitute an electrical wiring including a ground wiring, a power supply wiring, and / or a signal wiring.

  The resin layer 12 functions as a support member that supports the conductive layer 13 and an insulating member that suppresses a short circuit between the conductive layers 13. For example, the resin layer 12 is formed of a resin material such as an epoxy resin or a polyimide resin. The average thickness is set to 3 μm or more and 30 μm or less, for example. The resin layer 12 preferably contains an inorganic insulating filler formed of an inorganic insulating material such as silicon oxide or silicon nitride. The inorganic insulating filler is 30% by volume or more and 70% by volume of the resin layer 12. It is desirable to include the following.

  The conductive layer 13 transmits grounding power, power supply power, or an electrical signal, is formed on the base 9 or the resin layer 12, and is separated from each other in the thickness direction via the base 9 or the resin layer 12. For example, what was formed with metal materials, such as copper, silver, gold | metal | money, aluminum, nickel, or chromium, can be used, and the average thickness is set to 3 micrometers or more and 20 micrometers or less.

  The via conductors 14 electrically connect the conductive layers 13 that are separated from each other in the thickness direction, and are formed in a columnar shape that becomes narrower toward the core substrate 7. For example, copper, silver, gold, aluminum A material formed of a conductive material of nickel or chromium can be used.

  On the other hand, an optical waveguide member 6 is formed on the upper surface of the wiring substrate 5, and the optical semiconductor element 2 is mounted on the upper surface of the optical waveguide member 6. The optical waveguide member 6 has a function of transmitting an optical signal, and includes a clad layer 15, a core layer 16, a notch C, a mirror 17, a connection pad 18, and a through conductor 19. The core layer 16, the notch C, and the mirror 17 constitute an optical wiring that transmits an optical signal.

  The clad layer 15 has a function as a protective member of the core layer 16 and a function of confining an optical signal in the core layer 16. The clad layer 15 is formed in a flat plate shape surrounding the core layer 16. Resin, polysilanol resin, polysilane resin, polyimide resin, silicone resin, polystyrene resin, polycarbonate resin, polyamide resin, polyester resin, phenol resin, polyquinoline resin, polyquinoxaline resin, polybenzoxazole resin In addition, those formed of a translucent material such as polybenzothiazole resin or polybenzimidazole resin can be used.

  The clad layer 15 has an optical signal transmittance of, for example, 90% to 100%, and a thickness of, for example, 30 μm to 200 μm. The transmittance is measured by a method according to ISO13468-1: 1996.

  The clad layer 15 includes a flat plate-like first clad layer 15a and a flat plate-like second clad layer 15b laminated on the upper surface of the first clad layer 15a. The first clad layer 15a and the second clad layer 15b are preferably made of the same translucent material. The first cladding layer 15a has a thickness set to, for example, 10 μm or more and 100 μm or less.

  The core layer 16 transmits an optical signal. As shown in FIGS. 1B and 2A, the core layer 16 is surrounded by the first cladding layer 15a and the second cladding layer 16b in the longitudinal direction (X The refractive index is higher than that of the cladding layer 15. Therefore, the optical signal is totally reflected at the interface between the core layer 16 and the clad layer 15 and the reflection is repeated, whereby the optical signal can be transmitted along the longitudinal direction in the core layer 16.

  The core layer 16 is made of, for example, an epoxy resin, an acrylic resin, a polysilanol resin, a polysilane resin, a polyimide resin, a silicone resin, a polystyrene resin, a polycarbonate resin, a polyamide resin, a polyester resin, a phenol resin, or a polyquinoline resin. In addition, those formed of a light-transmitting material such as a polyquinoxaline resin, a polybenzoxazole resin, a polybenzothiazole resin, or a polybenzimidazole resin can be used. The core layer 16 has an optical signal transmittance of, for example, 90% to 100%, a refractive index of, for example, 1.0001 times to 1.1 times that of the cladding layer 15, and a width of, for example, 10 μm. The thickness is set to 100 μm or less and the thickness is set to 10 μm or more and 100 μm or less. The refractive index is measured by a method according to ISO 489: 1999.

  For example, the core layer 16 is preferably formed partially on the upper surface of the first cladding layer 15a, the lower surface is in contact with the first cladding layer 15a, and the side surface and the upper surface are in contact with the second cladding layer 15b. . Further, as shown in FIGS. 2A and 2B, the core layer 16 preferably overlaps with the uppermost conductive layer 13 in a plan view. In particular, the entire core layer 16 is the uppermost conductive layer. It is desirable to overlap with 13 in plan view.

  The cladding layer 15 and the core layer 16 are formed with notches C that are recessed from the upper surface of the cladding layer 15 in the thickness direction. The notch C is surrounded by a vertical cross section perpendicular to the longitudinal direction of the core layer 16 and an inclined surface formed by inclining the vertical cross section about the width direction (Y direction) of the core layer 16 as a rotation axis. Space. The vertical cross section includes the end face of the core layer 16 through which the optical signal passes, and the length along the thickness direction is set to 20 μm or more and 200 μm or less. The inclined surface is formed immediately below the light emitting / receiving portion of the optical semiconductor element 2, and the inclination angle with respect to the lower surface of the cladding layer 15 is set to 40 ° or more and 50 ° or less, for example. Although not shown, the cutout portion C is sealed with, for example, an underfill containing a translucent resin.

  A mirror 17 is formed on the inclined surface. The mirror 17 has a function of changing the transmission direction of the optical signal. Specifically, when the optical semiconductor element 2 is a light-emitting element, the mirror 17 reflects the optical signal transmitted from the light-emitting portion of the light-emitting element toward the inclined surface, thereby increasing the transmission direction of the optical signal. The optical signal can be transmitted to the core layer 16 from the direction to the longitudinal direction. For example, when the optical semiconductor element 2 is a light receiving element, the mirror 17 reflects the optical signal transmitted from the core layer 16 toward the inclined surface, thereby changing the transmission direction of the optical signal from the longitudinal direction to the thickness direction. The light signal can be transmitted to the light receiving portion of the light receiving element. The mirror 17 is made of a metal material such as gold, and the thickness with respect to the inclined surface is set to, for example, 100 nm or more and 5 μm or less.

  On the other hand, connection pads 18 are formed on the upper surface of the cladding layer 15. The connection pads 18 are electrically connected to the bumps 4 and can be formed of, for example, a metal material such as copper, silver, gold, aluminum, nickel, or chromium, and have an average thickness. It is set to 3 μm or more and 20 μm or less.

  The through conductor 19 electrically connects the connection pad 18 and the conductive layer 13 and is formed in a cylindrical shape that penetrates the cladding layer 15 in the thickness direction directly below the connection pad 18. For example, copper, silver, What was formed with metal materials, such as gold | metal | money, aluminum, nickel, or chromium, can be used.

  Thus, the optical wiring module 1 described above transmits an electrical signal through the through-hole conductor 10, the conductive layer 13, the via conductor 14, the through conductor 19, the connection pad 18, and the bump 4. By converting the optical signal and transmitting the optical signal through the notch C, the mirror 17, and the core layer 16, a desired function is exhibited.

  On the other hand, in the optical waveguide member 6 of the present embodiment, as shown in FIG. 2A, the core layer 16 includes a lower surface having a first contact surface 16a1 that is in surface contact with the upper surface of the first cladding layer 15a, From the first contact surface 16a1 and the second contact surface 16a2, an upper surface having a second contact surface 16a2 that is in surface contact with the two cladding layers 15b and at least partially overlaps the first contact surface 16a1 in plan view. And a side surface having a protruding portion 16b protruding outward.

  As a result, since the core layer 16 has the protrusions 16b, the width of the upper surface and the lower surface with respect to the maximum value of the width in the cross section perpendicular to the longitudinal direction of the core layer 16 can be reduced. The length of the diagonal line L1 that connects the first corner part 16c1 located at the second corner part 16c2 located between the upper surface and the side surface is shortened, and the difference in length between the diagonal line L1 and the distance L2 between the upper and lower surfaces is reduced. it can. Therefore, compared with the core layer whose cross section perpendicular to the longitudinal direction is rectangular, the optical signal caused by the phase difference of the optical signals with different traveling paths is reduced by reducing the difference in traveling distance depending on the traveling path of the optical signals. Thus, the optical waveguide member 6 having excellent signal transmission characteristics can be obtained.

  In addition, since the core layer 16 has the first contact surface 16a, the adhesive strength between the lower surface of the core layer 16 and the upper surface of the first cladding layer 15a can be increased. Therefore, when stress is applied to the optical wiring board 3, It is possible to reduce the peeling of the lower surface of the core layer 16 and the upper surface of the first cladding layer 15a due to the peeling generated on the boundary surface 15c between the upper surface of the first cladding layer 15a and the lower surface of the second cladding layer 15b. Similarly, since the core layer 16 has the second contact surface 16b, the adhesive strength between the upper surface of the core layer 16 and the lower surface of the second cladding layer 15b can be increased, so that the upper surface of the core layer 16 and the second cladding layer 15b Peeling can be reduced. Therefore, by reducing the peeling of the core layer 16 and the clad layer 15, it is possible to reduce the distortion and cracking of the core layer 16, reduce the scattering and leakage of the optical signal, and reduce the loss of the optical signal. The optical waveguide member 6 having excellent signal transmission characteristics can be obtained.

  In addition, since the core layer 16 has the protruding portion 16b, the adhesive strength between the side surface of the core layer 16 and the cladding layer 15 can be increased by the anchor effect, so that the upper surface of the first cladding layer 15a and the lower surface of the second cladding layer 15b can be increased. It is possible to reduce peeling between the side surface of the core layer 16 and the cladding layer 15 due to peeling that occurs on the boundary surface 15c.

  The widths of the first contact surface 16a1 and the second contact surface 16a2 are preferably set to 10 μm or more and 100 μm or less. Further, the distance along the width direction between the protruding portion 16b and the first corner portion 16c1 and the distance along the width direction between the protruding portion 16b and the second corner portion 16c2 are set to 5 μm or more and 30 μm or less. It is desirable that the width is set to 5% or more and 50% or less of the width of the first contact surface 16a1 and the second contact surface 16a2.

  It is desirable that the protruding amount of the side surface of the core layer 16 increases from the first corner portion 16c1 and the second corner portion 16c2 toward the protruding portion 16b. The side surface of the core layer 16 includes a first side surface d1 that connects the protruding portion 16b and the first corner portion 16c1 of the first contact surface 16a1, and a second corner portion of the protruding portion 16b and the second contact surface 16a2. It is desirable to have the 2nd side surface d2 which connects 16c2. As a result, the cross section perpendicular to the longitudinal direction of the core layer 16 is hexagonal, and the difference in travel distance that varies depending on the travel path of the optical signal can be reduced.

  In addition, the first side surface d1 and the second side surface d2 of the core layer 16 are preferably concave curved shapes recessed in the core layer 16. As a result, the adhesive strength between the side surface of the core layer 16 and the cladding layer 15 can be increased by the anchor effect by the concave curved surface.

  The first contact surface 16a1 is smaller in distance along the thickness direction with the boundary surface 15c of the first cladding layer 15a and the second cladding layer 15b than the second contact surface 16a2 and has a width of the second contact surface. It is desirable that it be larger than the surface 16a2. In particular, it is desirable that the first contact surface 16a1 is flush with the boundary surface 15c. As a result, the first contact surface 16a1 is easily affected by peeling at the boundary surface 15c when the distance along the thickness direction with the boundary surface 15c is smaller than the second contact surface 16a2. The adhesive strength between the upper surfaces of 16a1 and the first cladding layer 15a can be increased, and the peeling between the upper surfaces of the first contact surface 16a1 and the first cladding layer 15a can be reduced. Furthermore, the first contact surface 16a1 is preferably wider than the first side surface 16d1 and the second side surface 16d2 from the viewpoint of adhesive strength with the upper surface of the first cladding layer 15a. Note that the width of the first contact surface 16a1 is desirably set to be 1.1 to 2 times the second contact surface 16a2, and 1.1 times the first side surface 16d1 and the second side surface 16d2. It is desirable to set it to 2 times or less.

  Further, it is desirable that the distance between the first contact surface 16a1 and the protruding portion 16b in the thickness direction is smaller than that of the second contact surface 16a2. As a result, when the distance between the first contact surface 16a1 and the boundary surface 15c along the thickness direction is smaller than the second contact surface 16a2, the side surface of the core layer 16 and the first contact surface 16a1 of the cladding layer 15 are provided. By increasing the adhesive strength on the side, it is possible to reduce the peeling between the side surface of the core layer 16 and the clad layer 15 that occurs from the first contact surface 16a1 side due to the peeling that occurs on the boundary surface 15c. The distance between the first contact surface 16a1 and the protruding portion 16b is preferably set to be 0.5 to 0.9 times the distance between the second contact surface 16a2 and the protruding portion 16b.

  In addition, the first contact surface 16 a 1, the second contact surface 16 a 2, and the protruding portion 16 b are preferably formed continuously along the longitudinal direction of the core layer 16. As a result, the optical waveguide member 6 having excellent signal transmission characteristics and signal transmission reliability over the entire length of the core layer 16 can be obtained.

  Next, the manufacturing method of the optical wiring module 1 mentioned above is demonstrated based on FIGS.

(Preparation of wiring board 5)
(1) The core substrate 7 is produced. Specifically, for example, it is performed as follows.

  First, for example, a plurality of resin sheets including an uncured resin and a base material are laminated, and the substrate 9 is produced by heating and pressing to cure the uncured resin. The uncured state is an A-stage or B-stage according to ISO 472: 1999. Next, a through hole penetrating the base 9 in the thickness direction is formed by, for example, drilling or laser processing. Next, the cylindrical through-hole conductor 10 is formed by depositing a conductive material on the inner wall of the through-hole by, for example, electroless plating, electroplating, vapor deposition, CVD, or sputtering. Further, a conductive material layer is formed by depositing a conductive material on the upper surface and the lower surface of the substrate 9. Next, the inside of the cylindrical through-hole conductor 10 is filled with a resin material or the like to form the insulator 11. Next, a conductive material is deposited on the exposed portion of the insulator 11, and then the conductive layer material layer is patterned by a conventionally known photolithography technique, etching, or the like to form the conductive layer 13.

  As described above, the core substrate 7 can be manufactured.

  (2) A pair of wiring layers 8 are formed on both sides of the core substrate 7 to produce the wiring substrate 5. Specifically, for example, it is performed as follows.

  First, an uncured resin is disposed on the conductive layer 13, and the resin layer 12 is formed on the conductive layer 13 by further heating and curing the resin while heating and fluidly adhering the resin. Next, via holes are formed in the resin layer 12 by, for example, a YAG laser device or a carbon dioxide laser device, and at least a part of the conductive layer 13 is exposed in the via holes. Next, the via conductor 13 is formed in the via hole and the conductive layer 13 is formed on the upper surface of the resin layer 12 by, for example, a semi-additive method, a subtractive method, or a full additive method. By repeating this process, the wiring layer 8 can be formed.

  As described above, the wiring board 5 shown in FIG. 3A can be manufactured.

(Production of optical wiring board 2)
(3) As shown in FIG. 3B, a first cladding layer 15a is formed on the upper surface of the wiring substrate 5. Specifically, for example, it is performed as follows.

  An uncured first cladding layer precursor is applied to the upper surface of the wiring substrate 5, and the first cladding layer precursor is exposed and cured to form the first cladding layer 15 a on the upper surface of the wiring substrate 5.

  The application is performed using a spin coater, bar coater, roll coater, spray coater or the like. The exposure is performed using, for example, ultraviolet light having a wavelength band of 250 nm or more and 400 mm or less, and the exposure amount is set to 500 mJ or more and 2000 mJ or less, for example. The exposure amount is measured by a light meter.

  (4) As shown in FIG. 4A, the core layer 16 is partially formed on the upper surface of the first cladding layer 15a. Specifically, for example, it is performed as follows.

  As shown in FIGS. 4B to 6A, an uncured core layer precursor 16x is applied to the upper surface of the first cladding layer 15a, and the core layer is used using a mask 20 having an elongated transmission region T. The core layer 16 is partially formed on the upper surface of the first cladding layer 15a by partially exposing and curing the precursor 16x and etching the uncured portion.

  Application and exposure can be performed in the same manner as the first cladding layer 15a. Etching can be performed using a solution containing a propylene glycol monomethyl ether acetate solution or the like.

  Here, as the mask 20, a gray tone mask in which the transmittance of the internal T 1 is higher than that of the peripheral portion T 2 in the transmissive region T is used, and the transmissive region T is disposed immediately above the conductive layer 13, thereby forming the shape described above. The core layer 16 can be formed.

  That is, since the core layer 16 is formed on the upper surface of the first cladding layer 15a, the first contact surface 16a1 can be formed. In addition, since the transmittance in the transmission region inside T1 is high, the core layer precursor 16x is inhibited from being etched when the region overlapping the transmission region inside T1 in a plan view is cured in the thickness direction. A second contact surface 16 a 2 can be formed on the upper surface of the layer 16. The transmitted light inside the transmissive region T1 is diffused toward the outside of the transmissive region T. Therefore, the width of the first contact surface is made larger than the second contact surface 16a2 by adjusting the exposure amount. Can do.

  Further, since the transmissive region peripheral portion T2 has a low transmittance and the transmissive region T is disposed immediately above the conductive layer 13, when the core layer precursor 16x is exposed, the irradiation light from above and the reflected light from the conductive layer 13 As a result, only the central portion in the thickness direction of the region overlapping the transmission region peripheral portion T2 of the core layer precursor 16x in a plan view is cured. Further, in the region that overlaps the transmission region peripheral portion T2 of the core layer precursor 16x in plan view, the irradiation light and the reflected light become lower toward the outside of the transmission region T, so that the core layer precursor 16x is positioned at the central portion in the thickness direction. When the thickness of the cured region to be reduced decreases toward the outside of the transmission region T, the first side surface 16d1 and the second side surface 16d2 can be formed. Thus, the protrusion 16b can be formed by forming the first side surface 16d1 and the second side surface 16d2. Further, since the protrusion 16b is formed by diffusion of transmitted light inside the transmission region T1 and diffusion of reflected light from the conductive layer 13, the distance from the first contact surface 16a1 is the second contact surface. It can be formed to be smaller than 16a2. Moreover, the 1st side surface 16d1 and the 2nd side surface 16d2 can be formed in a concave curved surface by adjusting the transmittance | permeability of the permeation | transmission area | region T suitably. In addition, as for the permeation | transmission area | region peripheral part T2, it is desirable for the transmittance | permeability to become small toward the outer side of the permeation | transmission area | region T. FIG.

  The transmittance of the inside of the transmissive region T1 is set to, for example, 90% or more and 100% or less, and the transmittance of the transmissive region peripheral portion T2 is set to, for example, 10% or more and 90% or less. Further, the transmittance of the inside T1 of the transmissive region is set to 1.1 times or more and 10 times or less of the transmissive region peripheral portion T2, for example.

  (5) As shown in FIG. 6B, the second cladding layer 15b is formed on the upper surface of the first cladding layer 15a, and the cladding layer 15 surrounding the core layer 16 is formed. Specifically, for example, it is performed as follows.

  An uncured second cladding layer precursor is applied to the upper surface of the first cladding layer 15a, the side surface and the upper surface of the core layer 16 are surrounded by the second cladding layer precursor, and the second cladding layer precursor is exposed and cured. Thus, the second cladding layer 15b is formed on the upper surface of the first cladding layer 15a. Application and exposure can be performed in the same manner as the first cladding layer 15a.

  (6) As shown in FIG. 7A, the through conductor 18 is formed in the cladding layer 15 and the core layer 16, and the connection pad 19 is formed on the upper surface of the cladding layer 15. Specifically, for example, it is performed as follows.

  First, a through-hole penetrating the cladding layer 15 and the core layer 16 in the thickness direction is formed by, for example, drilling or laser processing. Next, the through conductor 18 is formed in the through hole and the connection pad 19 is formed on the upper surface of the cladding layer 15 by, for example, a semi-additive method, a subtractive method, or a full additive method.

  (7) As shown in FIG. 7B, the notch C is formed in the clad layer 15 and the core layer 16, and the mirror 17 is formed on the inclined surface of the notch C, whereby the optical waveguide member 6 is formed. The optical wiring board 3 is manufactured. Specifically, for example, it is performed as follows.

  First, a notch C is formed by making a cut from the surface of the second cladding layer 15b toward the first cladding layer 15a using, for example, a dicing blade whose tip is set to a desired shape. Next, the mirror 17 is formed by, for example, an electroless plating method, an electroplating method, a vapor deposition method, a CVD method, or a sputtering method.

  As described above, the optical waveguide member 6 can be formed by forming the optical waveguide member 6 on the upper surface of the wiring substrate 5.

(Production of optical wiring module 1)
(8) The optical semiconductor module 2 shown in FIG. 1 can be manufactured by flip-chip mounting the optical semiconductor element 2 on the optical wiring substrate 3 via the bumps 4.

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

  For example, in the above-described embodiment of the present invention, the configuration in which two resin layers are stacked in the wiring layer has been described as an example, but any number of resin layers may be stacked.

  Moreover, although embodiment mentioned above demonstrated the structure which used the resin substrate as a wiring board to the example, you may use the metal core board | substrate and ceramic substrate which coat | covered the metal plate with resin as a wiring board.

  In the above-described embodiment of the present invention, the first side surface and the second side surface are described as an example of a concave curved shape recessed in the core layer. As shown in FIG. The first side surface 16d1A and the second side surface 16d2A may be formed in a planar shape. In this case, signal transmission characteristics can be improved.

  Moreover, although embodiment of this invention mentioned above demonstrated to the example the structure which formed the core layer which has a 1st contact surface, a 2nd contact surface, and a protrusion part continuously along a longitudinal direction, 1st The contact surface, the second contact surface, and the protruding portion may be formed on at least a part of the core layer, and the core layer may be formed with a rectangular cross-sectional shape along the longitudinal direction of a part. Absent.

  Moreover, although embodiment of this invention mentioned above demonstrated to the example the structure by which the mirror was formed in the inclined surface of a notch part, the mirror does not need to be formed.

  In the above-described embodiment of the present invention, the resin is cured by exposure in the steps (3), (4), and (5) to form the first cladding layer, the core layer, and the second cladding layer. However, other means may be used as a means for curing the resin. For example, the resin may be cured by heating.

  In the above-described embodiment of the present invention, the configuration in which the core layer is formed immediately above the conductive layer on the upper surface of the wiring board in the step (4) has been described as an example. A core layer having a first abutting surface, a second abutting surface, and a protruding portion by containing 30% by volume to 70% by volume of an inorganic insulating filler and increasing the reflectance of the resin layer at the time of exposing the core layer precursor May be formed in a region other than directly above the conductive layer.

DESCRIPTION OF SYMBOLS 1 Optical wiring module 2 Optical semiconductor element 3 Optical wiring board 4 Bump 5 Wiring board 6 Optical waveguide member 7 Core board 8 Wiring layer 9 Base | substrate 10 Through-hole conductor
DESCRIPTION OF SYMBOLS 11 Insulator 12 Resin layer 13, 13A Conductive layer 14 Via conductor 15, 15A Clad layer 15a, 15aA 1st clad layer 15b, 15bA 2nd clad layer 15c, 15cA Interface 16, 16A Core layer 16a1, 16a1A 1st contact Surface 16a2, 16a2A Second contact surface 16b, 16bA Protruding portion 16c1, 16c1A First corner 16c2, 16c2A Second corner 16d1, 16d1A First side 16d2, 16d2A Second side 17 Mirror 18 Through conductor 19 Connection pad 20 Mask C Notch L1 Diagonal L2 Distance between opposing faces

Claims (6)

A wiring substrate having a plurality of conductive layers and a resin layer that insulates the conductive layers; a first cladding layer disposed on the wiring substrate; and a second cladding layer laminated on an upper surface of the first cladding layer; A core layer surrounded by the first and second cladding layers and having a refractive index higher than that of the first and second cladding layers,
The core layer has a lower surface having a first contact surface in contact with the upper surface of the first cladding layer, and a surface contact with the second cladding layer, and at least a part of the first contact surface overlaps with the first contact surface in a plan view. possess a top surface having a second contact surface, and a side surface having a protruding portion which protrudes outside the said first and second abutment surface which,
The width of the first contact surface is larger than the width of the second contact surface;
Optical wiring board the core layer, characterized in that superimposed in plan view on the conductive layer of the uppermost layer of the wiring board. The optical wiring board according to claim 1,
The first abutment surface, the optical wiring board distance along the thickness direction of the front Symbol protrusion being less than said second contact surface. The optical wiring board according to claim 1,
The side, the light and having a first side surface connecting the said projecting portion of the first contact surface, a second side surface connecting the said projecting portion and the second abutment surface, the Wiring board . The optical wiring board according to claim 3 ,
The first contact surface is adjacent to the boundary surface between the first and second cladding layers in the thickness direction than the second contact surface;
The optical circuit board according to claim 1, wherein the first contact surface has a width larger than that of the second contact surface, the first side surface, and the second side surface. The optical wiring board according to claim 3 ,
The optical wiring board according to claim 1, wherein the first and second side surfaces are concave curved shapes recessed in the core layer. An optical wiring board according to claim 1 ;
An optical semiconductor element mounted on the optical wiring board ;
Optical wiring module with

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