JP2010085476A - Optical path converting body, and optical transmission substrate having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical path converting body enabling low-loss optical path conversion, and an optical transmission substrate having it. <P>SOLUTION: This optical path converting body 1 converts the transmission direction of light of an optical waveguide 4 and guides it to the outside, or converts the transmission direction of light from the outside and introduces it to the optical waveguide 4. The optical path converting body 1 includes an optical path converting section 2 that is disposed inside the optical waveguide 4, has a first core section 31a for transmitting light, and converts the transmission direction of the light of the optical waveguide 4 to another transmission direction, and a projecting section 3 that is disposed projectedly onto the optical waveguide 4 and has a second core section 31b that includes a contact surface 32 adherable to the top surface of the optical waveguide 4, is connected to the first core section 31a, and transmits the light converted into the another transmission direction by the optical path converting body 2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical path conversion body that converts an optical path and an optical transmission board including the same.

  In recent years, with the improvement of information processing capability of computers, in an integrated circuit (IC) such as a semiconductor large scale integrated circuit element (LSI, VLSI) used as a microprocessor, the degree of integration of transistors has been increased. The operating speed of the IC has reached the GHz level at the clock frequency. Along with this, there has been a demand for higher density and finer electrical wiring for electrically connecting electrical elements.

  However, increasing the density and miniaturization of electrical wiring tends to cause crosstalk and propagation loss of electrical signals. For this reason, an optical transmission technique in which an electrical signal inputted to and outputted from a semiconductor element is converted into an optical signal, and the optical signal is transmitted through an optical wiring such as an optical waveguide formed on a mounting substrate has been studied.

  In optical transmission technology using optical wiring, not only light is transmitted substantially parallel to the substrate, such as an optical waveguide formed on the surface of a circuit board, but for example, light is substantially transmitted to the substrate. An optical transmission technique that performs three-dimensional transmission of an optical signal in the same manner as an electrical signal by transmitting the signal vertically has been studied.

For example, Patent Document 1 discloses an optical path changer that transmits light from an optical element in a vertical direction and further changes the light path and transmits the light to an optical waveguide.
JP 2004-333922 A

  Since the core part of the optical path changer is only in contact with the clad part, there is a problem that the adhesion of the core part is low and the core part is easily peeled off.

  For example, the core portion of the optical path changer in Patent Document 1 is held by a light reflecting film made of metal provided on the contact surface with the optical waveguide. However, the adhesion between the core portion made of resin and the light reflecting film is weak, and the core portion of the optical path changer tends to be peeled off due to heat change or the like when used over a long period of time.

  The present invention has been devised to solve the problems in the prior art as described above, and the purpose thereof is to improve the adhesion of the core part, and it can be used for a long period of time, and has low loss. It is an object to provide an optical path changer that makes it possible to perform an optical path change, and an optical transmission board including the same.

  The present invention relates to an optical path changer for converting the light transmission direction of an optical waveguide and leading it to the outside or converting the light transmission direction from the outside and introducing it into the optical waveguide. An optical path conversion unit that is provided inside and has a first core part that transmits light, converts the light transmission direction of the optical waveguide to another transmission direction, and is provided so as to protrude on the optical waveguide. A protruding portion that includes a contact surface that can be in close contact with the upper surface of the optical waveguide, is provided continuously with the first core portion, and transmits light that has been converted to another transmission direction by the optical path conversion unit. It is related with the optical path change body which comprises the protrusion part which has a 2nd core part to make.

  It is preferable that the optical path conversion unit has a slope inclined with respect to the optical path of the optical waveguide, and further includes a light reflection film on the slope.

  The present invention also includes a first substrate having the optical waveguide on a main surface, and an optical transmission path connected to the first substrate by soldering so as to penetrate both main surfaces. The present invention relates to an optical transmission board comprising a second board and the optical path changer.

  The main surface of the second substrate is provided on the main surface facing the first substrate so as to protrude toward the first substrate, and between the optical path changer and the optical transmission path. It is preferable to further include a step portion having a second optical transmission line that interposes and optically couples them.

  According to the present invention, the projecting portion of the optical path changer has the second core portion including the contact surface that can be in close contact with the upper surface of the optical waveguide, whereby the contact surface of the second core portion and the optical waveguide are in close contact with each other. By doing so, the core part is held by the optical waveguide, and the core part is not easily peeled from the optical path changer. Therefore, it is possible to perform optical path conversion with low loss over a long period of time.

  The optical path conversion unit has an inclined surface that is inclined with respect to the optical path of the optical waveguide, and further includes a light reflecting film on the inclined surface, so that most of the light from the optical waveguide enters or leaves the optical path. Most of the light can be transmitted to the optical waveguide to perform highly efficient optical path conversion.

  An optical transmission board of the present invention includes a first board having an optical waveguide on a main surface, and an optical transmission path that is connected to the first board by soldering so as to penetrate both main surfaces. And a second substrate having an optical path changer. Thereby, since the protrusion part of the optical path changer narrows the interval between the first substrate and the second substrate, the reduction of the transmission loss of light between the first substrate and the second substrate is suppressed, A low-loss optical path conversion is enabled between the first substrate and the second substrate. In addition, since the protrusion of the optical path changer narrows the interval between the first substrate and the second substrate, the flux emitted from the solder is less likely to enter between the first substrate and the second substrate. Furthermore, since the contact surface is in close contact with the upper surface of the optical waveguide, it is possible to suppress the penetration of the flux into the optical path conversion unit and perform highly efficient optical path conversion between the optical waveguide and the optical transmission path.

  Since the step portion is provided on the main surface of the second substrate, the distance between the first substrate and the second substrate can be further narrowed by the protruding portion and the step portion. Intrusion between the second substrate and the second substrate can be suppressed, and highly efficient optical path conversion between the optical waveguide and the optical transmission path can be performed. Further, since the step portion and the optical path changer are close to each other, light leakage between the substrates can be prevented, and crosstalk and loss between channels can be suppressed.

  The optical transmission board according to the embodiment of the present invention will be described with reference to the drawings. However, the drawings are only examples of the embodiments, and the present invention is not limited to them.

  FIG. 1 is a cross-sectional view schematically showing an example of an optical path changer of the present invention and an optical waveguide provided with the optical path changer. DESCRIPTION OF SYMBOLS 1 is an optical path changer, 2 is an optical path change part, 3 is a protrusion part, 31 is a core part, 31a is a 1st core part, 32a is a 2nd core part, 32 is a contact surface, 33 is a slope, 34 is a clad Reference numeral 4 denotes an optical waveguide, 41 denotes a core part of the optical waveguide, 42 denotes a cladding part of the optical waveguide, and 6 denotes a first substrate.

  Fig.2 (a) is a perspective view which shows typically an example of the optical path change body of this invention. In FIG. 2, 5 indicates a light reflecting film. FIG. 2B is a cross-sectional view of the optical path changer 1 and the optical waveguide 4 of FIG. 2A cut along the same direction as the light transmission direction of the core portion 41.

  FIG. 3 is a cross-sectional view schematically showing the position of the length and height of the contact surface 32 of the optical path changer of the present invention.

  Moreover, (a)-(h) of FIG. 4 is sectional drawing which shows typically the manufacturing process of the optical path changing body of this invention. FIGS. 5E to 5H are top views schematically showing manufacturing steps of the optical path changer of FIGS. 4E to 4H.

  Further, in FIG. 6, 8 is a second substrate, 81 is a core portion of a through-type optical transmission path of the second substrate, 82 is a cladding portion of the through-type optical transmission path of the second substrate, and 9 is an optical semiconductor element. 9A is a light emitting / receiving unit, 10 is a stepped part, 14 is a metal layer, and 15 is a solder ball.

  The optical path changing body 1 of the present invention includes an optical path changing portion 2 and a protruding portion 3. Each configuration will be described below.

(Optical path conversion unit 2)
The optical path conversion unit 2 is provided inside the optical waveguide 4 and converts the light transmission direction of the optical waveguide 4 to another transmission direction.

  The optical path conversion unit 2 is made of a transparent resin capable of transmitting light. As a material, polysilane that causes a photobleaching phenomenon in which a refractive index decreases when irradiated with light, or a portion other than a portion irradiated with light is developed. Examples thereof include a photosensitive transparent acrylic resin and a transparent epoxy resin that can be removed.

  The optical path conversion unit 2 includes a core part (hereinafter, first core part 31a) and a clad part (not shown). The first core portion 31a has a relative refractive index difference of 1 to 3% higher than that of the cladding portion, and can confine an optical signal in the first core portion and propagate to the core portion 41 of the optical waveguide with low loss.

  In addition, the optical waveguide 4 in which the optical path changing unit 2 is provided is also configured in a coaxial structure by the core part 41 of the optical waveguide and the clad part 42 of the optical waveguide, like the optical path changing unit 2. The optical waveguide is manufactured by a general method. Specific dimensions of the optical waveguide 4 include, for example, a lower thickness of the cladding 42 of 15 to 25 μm, a cross-sectional size of the core 41 of 35 to 100 μm square, and an upper thickness of the cladding 42 of 15 to 25 μm.

  The first core portion 31 a is provided so as to correspond to the core portion 41 of the optical waveguide 2. Specifically, when the optical path conversion unit 2 and the optical waveguide 4 provided with the optical path conversion unit 2 are seen through from above, the first core unit 31 a is provided so as to be aligned with the core unit 41 of the optical waveguide 2.

  The optical path conversion unit 2 has an inclined surface 33 that is inclined with respect to the optical path of the optical waveguide 4. The inclined surface 3 is inclined with respect to the optical axis direction of the optical waveguide 2. For example, the light path direction is changed 90 degrees by the inclined surface 33 inclined at 45 degrees with respect to the optical axis direction, and the light path is changed. The slope 33 is produced by a dicing blade having a cross section of approximately 45 degrees, for example.

  A light reflecting film 5 is further provided on the inclined surface 33 (see FIG. 2B). Specifically, the light reflecting film 5 is provided on the inclined surface 33 by, for example, thinly coating or applying a metal such as gold, silver, copper, aluminum, or nickel.

(Protrusion 3)
As shown in FIGS. 1 and 2, the protruding portion 3 is provided so as to protrude on the main surface of the optical waveguide 4. The thickness of the protrusion part 3 is 1-200 micrometers.

  Since the obtained protruding portion 3 protrudes from the optical waveguide 4, it has good visibility and serves as a marker when mounting external components. In addition, when formed with high accuracy by a photo process, the projecting portion 3 also serves as a fitting part and can perform mounting positioning, thus enabling highly efficient light transmission without alignment. And Further, the distance between the optical paths can be shortened at the time of mounting, and the optical loss can be reduced. When the height of the convex portion is sufficient, it is possible to couple the optical components.

  The protrusion part 3 has the 2nd core part 31b. The second core unit 31b is optically coupled with the light converted into another transmission direction by the optical path conversion unit 2. The second core portion 31b is made of a transparent resin capable of transmitting light in the same manner as the optical path changing portion 2. The material is the same as that of the optical path changing unit 2. The second core portion 31 b refers to a portion having a high refractive index in the refractive index distribution of the protruding portion 3. A portion other than the second core portion 31b in the protruding portion 3 becomes the cladding portion 34 of the protruding portion 3 having a refractive index lower than that of the second core portion 31b. In FIG. 1 and FIG. 2 (b), the portion other than the core portion 31 is a clad portion 34 of a protruding portion.

  The second core portion 31b has a circular cross section with respect to the optical transmission direction, and its diameter is about 35 to 100 μm.

  The second core portion 31 b is provided so as to correspond to the first core portion 31 a and the core portion 41 of the optical waveguide 2. Specifically, when the optical path changer 1 and the optical waveguide 4 provided with the optical path changer 1 are seen through from above, the second core portion 31b has the same straight line as the first core portion 31a and the core portion 41 of the optical waveguide 2. Are arranged in a line.

  When a plurality of core portions 41 are provided in the optical waveguide 4, the second core portion 31 b corresponds to each core portion 41 in the protruding portion 3 of the optical path changing body 1 as shown in FIG. 2. Are provided. Thereby, the area of the contact surface 32 which will be described later increases, and strong adhesion is obtained between the optical waveguide 4 and the contact surface 32.

  In the protruding portion 3, the second core portion 31 b has a contact surface 32. The contact surface 32 refers to a portion in contact with the upper surface of the optical waveguide 4 in the second core portion 31. The contact surface 32 is provided on the optical waveguide 4 by, for example, photolithography. The contact surface 32 and the optical waveguide 4 are in close contact so that the contact surface 32 holds the optical path conversion body 1 in the optical waveguide 4. It is difficult to peel off, and low-loss optical path conversion can be performed. In particular, when both the protrusion 3 and the optical waveguide 4 are made of epoxy resin, the contact surface 32 of the protrusion 3 and the optical waveguide 4 can be hydrogen-bonded at the molecular level. Adhesion can be improved.

  Examples of the material for the contact surface 32 include polysilane that causes a photobleaching phenomenon in which the refractive index decreases when irradiated with light, or a photosensitive transparent acrylic resin, transparent epoxy resin, or the like that can be removed by development other than the irradiated portion. be able to.

  Both the contact surface 32 and the optical waveguide 4 are preferably the same type of resin, and more preferably both are epoxy resins. Since both the contact surface 32 and the optical waveguide 4 are made of epoxy resin, a hydrogen bond is generated between the contact surface 32 and the optical waveguide 4, so that strong adhesion between the contact surface 32 and the optical waveguide 4 can be obtained. .

  Here, in FIG. 3, the lengths A and B of the contact surface 32 in the optical path changer 1 and the height C of the optical path changer 2 are shown. The length A indicates the length of the contact surface 32 on the inclined surface 33 side of the optical path conversion unit 2, and the length B indicates the length of the contact surface 32 on the vertical surface side of the optical path conversion unit 2.

  The length A is 10 to 1000 μm. The length B is 10 to 1000 μm. The height C is 10 to 300 μm.

  Here, the length A and the length B are preferably equal to each other. By satisfying this, peeling of the core portion 31 of the optical path changing body 1 can be suppressed from relaxation of stress due to expansion.

Further, the relationship between the height C and the length A of the optical path conversion unit 2 is preferably A = B> C. By satisfying this, peeling of the core part 31 of the optical path changer 1 can be suppressed by relaxation of stress due to expansion. Hereinafter, the optical path changer 1 of the present invention and the method of manufacturing the optical waveguide 4 for providing the same Will be described with reference to FIGS.

  For example, a photosensitive polymer resin such as an ultraviolet curable acrylic resin or an epoxy resin is used to apply a low refractive index photosensitive polymer resin to the upper surface of the first substrate 6, heat cure, Development is performed by irradiating with ultraviolet light through a mask, thereby removing the resin in the non-irradiated part of the ultraviolet light and forming the lower part of the cladding part 42.

  Further, a photosensitive polymer material having a high refractive index and a refractive index higher than that of the clad portion 42 is applied on the lower portion of the clad portion 42, heat-cured, and then developed by irradiation with ultraviolet light through a photomask. After performing the above, the resin in the portion not irradiated with ultraviolet light is removed to form the core portion 41. Thereafter, a material having a low refractive index is applied onto the core portion 41, and development and post-baking are performed by irradiating ultraviolet light through a photomask, thereby forming a cladding portion 42 around the core portion. 4 is formed (FIG. 4A).

  Next, a groove for forming a 45 ° optical path conversion surface is formed in the optical waveguide 4 by stamping, etching, dicing, laser processing, or the like (FIG. 4B).

  Further, a light reflecting film 5 is produced by providing a metal or a low refractive index material on the produced groove (FIG. 4C) .As a metal to be formed on the light reflecting film 3, gold (Au), silver (Ag) ), Platinum (Pt), aluminum (Al), copper (Cu), or the like, or a low-refractive index body made of a material having a high reflectance or a material having a lower refractive index than that of the core portion 41. Specifically, a metal. The light reflecting film 5 is obtained by evaporating.

  In order to remove the metal adhering to the portion other than the light reflection film 5 of the optical waveguide 4, excess metal is diced (FIG. 4D).

  Further, a photosensitive polymer material having a high refractive index is applied from above the optical waveguide 4 (FIG. 4 (e) and FIG. 5 (e)).

  After heat-curing, development is performed after irradiating ultraviolet light through a photomask to remove the resin in the non-irradiated part of the ultraviolet light, thereby forming the first core part 31a and the second core part 31b ( FIG. 4 (f) and FIG. 5 (f)).

  Further, a photosensitive polymer material having a low refractive index is applied and heated and cured (FIGS. 4G and 5G). Thereafter, development is performed after irradiating ultraviolet light through a photomask to remove the resin in the non-irradiated part of the ultraviolet light, thereby forming the clad part of the optical path changing part 2 and the clad part 34 of the protruding part 3 ( FIG. 4 (h) and FIG. 5 (h)).

  The optical path changer 1 can be produced by the above method.

  FIG. 6 is a cross-sectional view schematically showing an example of the optical transmission board of the present invention.

  FIG. 6 shows an optical transmission substrate in which the first substrate 6 and the second substrate 8 are stacked and optically connected. An optical semiconductor element 9 is provided on the second substrate 8 of the optical transmission substrate, and a light emitting / receiving unit 9A is provided below the optical semiconductor element 9. Further, the optical path changing body 1 is provided on the first substrate 6. The light emitting / receiving unit 9A of the optical semiconductor element 9 and the optical path changer 1 are optically coupled. The second substrate 8 is provided with a through-type optical transmission path so as to penetrate the second substrate 8 in order to satisfy the optical coupling between the optical semiconductor element 9 light receiving / emitting unit 9A and the optical path changer 1. It has been. This penetrating optical transmission line includes a core part 81 and a clad part 82. The through-type optical transmission line has a circular cross section with respect to the optical transmission direction, the diameter is 100 to 200 μm, and the core portion 81 has a diameter of 35 to 100 μm.

  Further, the first substrate 6 and the second substrate 8 are electrically connected by solder balls 15 or the like. Note that an interval of about 1 to 1000 μm exists between the first substrate 6 and the second substrate 8 due to the solder balls 15.

  Solder balls mainly contain a flux due to an organic solvent and diffuse by heating. The first substrate 6 and the second substrate 8 are separated from each other by the vertical height of the solder ball, and the flux tends to adhere to the surfaces of the first substrate 6 and the second substrate 8 that face each other. is there. In general, the flux is colorless and transparent, but it becomes cloudy by reaction or turns brown with time, so adhering to the exposed surface of the optical transmission line tends to cause light loss, and light between the substrates. In some cases, it was difficult to realize the connection.

  In this embodiment, as shown in FIG. 6, a step portion 10 is provided on the first substrate 6, and together with the optical path changer 1 on the second substrate 8, the first substrate 6 and the second substrate 8 By closing the gap between them, the possibility that the flux covers the exposed surfaces of the first substrate 6 and the second substrate 8 can be reduced, and the reduction of the light propagation performance can be suppressed.

  The step portion 10 preferably has a thickness of 0.3 to 0.5 mm. The step part 10 is comprised from resin like an epoxy resin.

  The step portion 10 can also be formed by photolithography. A photosensitive resin having a required thickness is applied to the first substrate 6 and patterned by exposure and development. Thereby, excess photosensitive resin other than the part which becomes the step part 10 is removed by development.

  When the step portion 10 is provided, the penetrating optical transmission line provided on the first substrate 6 is provided to extend to the step portion 10. Thereby, an optical signal can be transmitted also in the step part 10.

It is sectional drawing which shows typically an example of the optical path change body of this invention. (A) is a perspective view which shows typically an example of the optical path changer of this invention, (b) is the cross section which cut | disconnected the optical path changer 1 and the optical waveguide 4 along the core part 41 and the core part 31 of (a) FIG. It is sectional drawing which shows typically the position of the length and the height of the contact surface 32 of the optical path changing body of this invention. (A)-(h) is sectional drawing which shows typically the manufacturing process of the optical path changing body of this invention. (E)-(h) is a top view which shows typically the manufacturing process of the optical path change body of FIG.3 (e)-(h). It is sectional drawing which shows typically an example of the optical transmission board | substrate of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical path conversion body 2 Optical path conversion part 3 Protrusion part 31 Core part 31a 1st core part 31b 2nd core part 32 Contact surface 33 Inclination 34 The clad part 4 of a protrusion part Optical waveguide 41 The core part 42 of an optical waveguide 42 Cladding portion 5 Light reflecting film 6 First substrate 8 Second substrate 81 Core portion 82 of penetrating optical transmission path of second substrate Cladding portion 9 of penetrating optical transmission path of second substrate 9 Optical semiconductor element 9A Light Light receiving / emitting part 10 of semiconductor element 9 Step part 14 Metal layer 15 Solder ball A Length B of contact surface 32 on the slope 33 side of optical path conversion part 2 Length C of contact surface 32 on the vertical surface side of optical path conversion part 2 Optical path Height of conversion part

Claims (4)

An optical path changer for converting the light transmission direction of the optical waveguide to be derived outside or converting the light transmission direction from the outside and introducing it into the optical waveguide,
An optical path conversion unit that is provided inside the optical waveguide, has a first core part that transmits light, and converts the transmission direction of the light of the optical waveguide to another transmission direction;
A projecting portion provided to project on the optical waveguide, including a contact surface capable of being in close contact with the upper surface of the optical waveguide, provided continuously with the first core portion, by the optical path changing unit; A protrusion having a second core for transmitting light converted in another transmission direction;
An optical path changer comprising:   The optical path conversion body according to claim 1, wherein the optical path conversion unit has a slope inclined with respect to the optical path of the optical waveguide, and further includes a light reflection film on the slope. A first substrate having an optical waveguide on a main surface;
A second substrate having an optical transmission line connected to the first substrate by solder and provided so as to penetrate both main surfaces;
The optical path changer according to claim 1 or 2,
An optical transmission board comprising:   The main surface of the second substrate is provided on the main surface facing the first substrate so as to protrude toward the first substrate, and between the optical path changer and the optical transmission path. 4. The optical transmission board according to claim 3, further comprising a step portion having a second optical transmission line that interposes and optically couples them.

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