Patent Document

BACKGROUND 
   1. Technical Field 
   The present invention relates to an optical transmission module and a method of manufacturing the same, particularly an optical transmission module in which positioning between a photoelectric element and an optical fiber can be achieved precisely and easily, and reduction in size and cost can be realized. 
   2. Related Art 
   A conventional optical transmission module is provided with a plurality of photoelectric elements such as light emitting elements or light receiving elements. In the optical transmission module, positioning of the photoelectric element and an optical fiber has been a serious problem. 
   When one photoelectric element is provided, the photoelectric element is housed in a metallic can package such as a TO (Transistor Outline) can package, and a so-called active alignment is performed in which positioning between the photoelectric element and an optical fiber receptacle section is performed in a state where the photoelectric element emits light or receives light. 
   SUMMARY 
   In order to achieve the object, one embodiment of the invention provides the following optical transmission module and the method of manufacturing the same. 
   According to an aspect of the present invention, an optical transmission module comprising: a substrate; an electric wiring section that is provided on the substrate; a photoelectric element that are mounted on the electric wiring section, and that emits an optical signal on the basis of a received electric signal or transmits an electric signal on the basis of a received optical signal; an optical part that comprises at least one of an optical conversion section and an optical fiber receptacle section, and that controls an optical path of optical signal between the photoelectric element and an optical fiber; a mounting support member that positions the photoelectric element; and a positioning mechanism that positions the optical part and the mounting support member. 
   In accordance with this aspect, the photoelectric element is positioned by the mounting support member, and the mounting support member and the optical part are positioned by the positioning mechanism. Accordingly, the photoelectric element and the optical part can be positioned precisely and easily through the mounting support member. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Exemplary embodiment of the present invention will be described in detail based on the following figures, wherein: 
       FIG. 1  is a sectional view illustrating the construction of an optical transmission module according to a first embodiment of the present invention; 
       FIGS. 2A and 2B  are diagrams illustrating the structure of a mounting support member according to a first embodiment of the invention; 
       FIGS. 3A to 3F  are diagrams illustrating a process of manufacturing an optical transmission module according to the first embodiment of the invention; 
       FIGS. 4A and 4B  are diagrams illustrating the structure of a mounting support member according to a second embodiment of the invention; 
       FIGS. 5A and 5B  are diagrams illustrating the structure of a mounting support member according to a third embodiment of the invention; 
       FIG. 6  is a sectional view illustrating the structure of an optical transmission module according to a fourth embodiment of the invention; 
       FIG. 7  is a sectional view illustrating the structure of an optical transmission module according to a fifth embodiment of the invention; 
       FIG. 8  is a sectional view illustrating the structure of an optical transmission module according to a sixth embodiment of the invention; and 
       FIGS. 9A and 9B  are sectional views illustrating the structure of an optical transmission module according to a seventh embodiment of the invention. 
   

   DETAILED DESCRIPTION 
   First Embodiment 
     FIG. 1  is a sectional view illustrating the construction of an optical transmission module according to a first embodiment of the invention. 
   The optical transmission module  1  includes a mounting support member  11 A, a plurality of photoelectric elements  12 , and an optical part  13 A. The mounting support member  11 A is provided on an electric wiring section  21  disposed on a substrate  2 . 
   (Electric Wiring Section) 
   The electric wiring section  21  is an electric wiring part such as a printed circuit board, a flexible printed circuit board, a lead frame wiring lines or the like. The electric wiring section  21  is disposed on the substrate  2  in advance. 
   (Mounting Support Member) 
   The mounting support member  11 A makes it possible to dispose the photoelectric element  12  in an optimal position on the electric wiring section  21  and to install the optical part  13 A in an optimal position in the positional relationship with the photoelectric element  12 . 
   The mounting support member  11 A is provided with a plurality of element positioning sections  111  and a plurality of optical part positioning sections  112 . The element positioning section  111  is used in positioning for disposing the photoelectric element  12  on an optimal position of the electric wiring section  21 , in order to connect the photoelectric element  12  to the electric wiring section  21 . 
   The optical part positioning section  112  is a convex portion (first convex portion) provided on the upper surface of the mounting support member  11 A. The optical part positioning section  112  is fitted into a concave portion (second concave portion)  13   a  provided in the optical part  13 A, so that the optical part  13 A can be fixed in a suitable position. 
   (Photoelectric Element) 
   The photoelectric element  12  is a light emitting element such as a light emitting diode or surface emitting laser, which converts an electric signal into an optical signal. When receiving an electric signal delivered through the electric wiring section  21 , the photoelectric element  12  emits a corresponding optical signal to deliver to optical fiber (not shown) through the optical part  13 A. Alternatively, the photoelectric element  12  may be a light receiving element, such as a photodiode, which receives an optical signal emitted from the optical fiber (not shown) through the optical part  13 A and converts the optical signal into an electrical signal to return. Further, as for the plurality of photoelectric elements  12  on the substrate  2 , light emitting elements and light receiving elements may be used. 
   As for the photoelectric element  12 , a light emitting element, such as surface emitting laser, or a light receiving element is used. However, any element, which performs photoelectric conversion, may be used. 
   (Optical Part) 
   The optical part  13 A includes a plurality of lens sections  131  and an optical fiber receptacle section  132 . The optical part  13 A has a function of effectively delivering an optical signal emitted from the photoelectric element  12  to the optical fiber  4 . 
   The lens section  131  condenses optical signals, which are diffusely emitted from the photoelectric element  12 , and performs photoelectric conversion so that the optical signals effectively enter the optical fiber. Alternatively, when a light receiving element is used as the photoelectric element  12 , the lens section condenses optical signals, which are diffusely emitted from the optical fiber, and performs photoelectric conversion so that the optical signals are effectively condensed and received into the photoelectric element  12 . 
   The optical fiber receptacle section  132  fits and fixes one end of a fiber holder  3 A holding the optical fiber  4  delivering an optical signal to an optimal position so that an optical signal emitted from the photoelectric element  12  is effectively received and an optical signal received in the photoelectric element  12  is effectively transmitted. 
   (Detailed Construction of Mounting Support Member) 
     FIGS. 2A and 2B  are diagrams illustrating the detailed structure of the mounting support member according to the first embodiment.  FIG. 2A  is a top view of the mounting support member  11 A and  FIG. 2B  is a sectional view taken along an A-A line of  FIG. 2A . 
   The mounting support member  11 A is a thin plate member having a substantially rectangular shape. The optical part positioning section  112  having a convex shape is provided on either side of the mounting support member  11 A in a longitudinal direction. Between two of the optical part positioning sections  112 , the plurality (four in  FIG. 2 ) of element positioning sections  111  are provided, having a width for positioning a width direction of the photoelectric element  12 . 
   The element positioning section  111  is a hole provided through the plane-shaped mounting support member  11 A. When the mounting support member  11 A is disposed on the electric wiring section  21 , the electric wiring section  21  is exposed through the element positioning section  111  without being covered by the mounting support member  11 A. Therefore, when the photoelectric element  12  is disposed in the element positioning section  111 , the electric connection between the photoelectric element  12  and the electric wiring section  21  can be achieved. 
   The wall surface of the element positioning section  111  is formed with an inclined surface  111   a . Therefore, when the photoelectric element  12  is mounted, mechanical interference hardly occurs. Such a structure makes mounting easy. 
   A taper  112   a  is formed at the side of the optical part positioning section  112  so that the optical part  13 A is easily fitted. 
   (Manufacturing Process of the First Embodiment) 
     FIGS. 3A to 3F  are diagrams illustrating a process of manufacturing an optical transmission module according to the first embodiment of the invention.  FIGS. 3B ,  3 D, and  3 F are sectional views taken along an A-A line of  FIGS. 3A ,  3 C, and  3 E, respectively. 
   First, the electric wiring section  21  is disposed on the substrate  2 . Then, the mounting support member  11 A is positioned and fixed in accordance with an electrode pattern of the electric wiring section  21  and other positional information, as shown in  FIGS. 3A and 3B . 
   The electric wiring section  21  is directly disposed on the substrate  2 , for example, by a method of printing a circuit board on the substrate  2 . 
   The mounting support member  11 A can be formed in a desired shape by resin molding, such as extrusion, or a cutting. 
   The mounting support member  11 A is used for determining an absolute position of the photoelectric element  12  with respect to the electric wiring section  21 . However, an absolute position of the photoelectric element  12  with respect to the electric wiring section  21  has a relatively high degree of freedom. Therefore, the mounting precision of the mounting support member  11 A with respect to the electric wiring section  21  may be relatively low, and mounting can be performed at a low cost. 
   Next, as shown in  FIGS. 3B and 3E , the plurality of photoelectric elements  12  are disposed using the element positioning section  111  of the mounting support member  11 A and fixed to the electric wiring section  21 . 
   The width of one side of the element positioning section  111  composed of a substantially rectangular hole slightly exceeds that of the photoelectric element  12 . Further, the photoelectric element  12  is disposed in accordance with the element positioning section of the mounting support member  11 A, so that the photoelectric element  12  can be easily disposed in a desired position. 
   The width of the other side of the element positioning section  111  is relatively larger than that of photoelectric element  12 . This is because a space required for connecting an electrode provided on the photoelectric element  12  and the electric wiring section  21  through wire-bonding using wire  12   a  should be secured. 
   After the fixing of the photoelectric element  12 , the electrode provided on the photoelectric element  12  and the electric wiring section  21  are connected through wire-bonding using the wire  12   a . Since heat is generated in the wire-bonding, the mounting support member  11 A is preferably formed of a material having resistance to the heat. 
   The wall surface of the element positioning section  111  is inclined, so that the size of the hole at the upper portion becomes larger than that of the hole at the lower portion, which makes it easy to dispose the photoelectric element  12 . 
   Next, as shown in  FIGS. 3C and 3F , the optical part  13 A is disposed on the mounting support member  11 A. At this time, the disposed position of the optical part  13 A is determined using two of the optical part positioning sections  112  of the mounting support member  11 A. As the convex-shaped optical part positioning section  112  of the mounting support member  11  is fitted into the concave portion  13   a  of the optical part  13 A, the plurality of lens sections  131  of the optical part  13  are respectively positioned on the corresponding photoelectric elements  12 . That is, the plurality of lens sections  131  can be disposed in suitable positions. 
   The optical part positioning section  112  is provided with the taper  112   a  so that the optical part  13 A is easily fitted into the optical part positioning section  112 . Therefore, when the optical part  13 A is positioned with respect to the mounting support member  11 A, mechanical interference hardly occurs. Such a structure makes mounting easy. 
   The optical part  13 A can be also formed in a desired shape by resin molding, such as extrusion, or a cutting. 
   The above-described process of manufacturing the optical transmission module according to the first embodiment is commonly applied to optical transmission modules according to other embodiments, which will be described below. 
   (Effect of the First Embodiment) 
   According to the first embodiment, the photoelectric element  12  and the optical part  13 A are directly positioned with respect to the mounting support member  11 A. Therefore, without an intermediate member such as a guide pin, positioning with high precision can be realized. Further, since the thickness of the mounting support member  11 A can be set to the thickness level of the photoelectric element  12 , the mounting support member can be manufactured at a low cost. 
   Further, even in the optical fiber receptacle  132 , positioning of the optical fiber can be realized without an intermediate member such as a guide pin. 
   Second Embodiment 
   An optical transmission module according to a second embodiment of the invention has alignment marks provided in a mounting support member, and the alignment marks are used for determining the disposed position of the photoelectric element  12 . 
     FIGS. 4A and 4B  are diagrams illustrating the structure of the mounting support member according to the second embodiment of the invention.  FIG. 4A  is a top view of the mounting support member  11 B, and  FIG. 4B  is a sectional view taken along a line A-A of  FIG. 4A . 
   The mounting support member  11 B according to the second embodiment has something in common with the mounting support member  11 A according to the first embodiment in that the mounting support member  11 B is a slim plate member having a substantially rectangular shape, the convex-shaped optical part positioning section  112  is provided on either side of the mounting support member  11 B in the longitudinal direction, and the plurality of element positioning sections  111  are provided between two of the optical part positioning sections  112 . However, the mounting support member  11 B is different from the mounting support member  11 A in that the alignment marks  113  are provided around each element positioning section  111 . 
   The alignment marks  113  are provided around the plurality of element positioning sections  111  of the mounting support member  11 B. The alignment mark is a straight-line mark provided around the element positioning section  111  and is a concave portion, which is provided in advance when the mounting support member  11 B is molded. 
   The plurality of alignment marks  113  are provided around each of the element positioning sections  111 . Optical positioning is performed such that a point, where the respective alignment marks  113  intersect each other when they are extended, overlaps the center of the optical element  12 . Then, the absolute position of the optical element  12  is determined. 
   Therefore, the width of the element positioning section  111  in the mounting support member  11 B may be relatively larger than that of the optical element  12 . Further, the wall surface of the element positioning section  111  does not have to be formed with the inclined surface  111   a.    
   When the photoelectric element  12  is positioned, mechanical positioning using the element positioning section  111  and optical positioning using the alignment marks  113  may be used together. 
   (Effect of the Second Embodiment) 
   According to the second embodiment, the photoelectric element  12  and the optical part  13 A are directly positioned with respect to the mounting support member  11 B. Therefore, without an intermediate member such as a guide pin, positioning with high precision can be realized. 
   Third Embodiment 
   An optical transmission module according to a third embodiment of the invention has one array positioning section provided in a mounting support member. The disposed position of an element array including a plurality of photoelectric elements is determined by the array positioning section. 
     FIGS. 5A and 5B  are diagrams illustrating the structure of the mounting support member according to the third embodiment of the invention.  FIG. 5A  is a top view of the mounting support member  11 C, and the  FIG. 5B  is a sectional view taken along a line A-A of  FIG. 5A .  FIGS. 5A and 5B  shows the element array  14  disposed inside the array positioning section  114 . 
   In the mounting support member  11 C, one array positioning section  114  and a plurality (for example, two) of optical part positioning sections  112  are provided. The array positioning section  114  is used in positioning for disposing the element array  14  on an optimal position of the electric wiring section  21 , in order to connect the element array  14  including the plurality of photoelectric elements to the electric wiring section  21 . 
   The element array  14  is where a plurality of photoelectric elements converting an electric signal into an optical signal are arranged. When the respective photoelectric elements receive an electric signal delivered through the electric wiring section  21 , the element array  14  emits a corresponding optical signal to deliver to the optical fiber  4  (not shown) through the optical part  13 A. When a light receiving element is used as a photoelectric element, the respective photoelectric elements receive an optical signal emitted from the optical fiber  4  (not shown) through the optical part  13 A and return the optical signal into an electric signal. 
   As for the photoelectric element included in the element array  14 , a light emitting element such as surface emitting laser or a light receiving element is used. However, any element which performs photoelectric conversion may be used. 
   The mounting support member  11 C is a slim plate member having a substantially rectangular shape. The convex-shaped optical part positioning section  112  is provided on either side of the mounting support member  11 C in a longitudinal direction. Further, between two of the optical part positioning sections  112 , one rectangular array positioning section  114  is provided. 
   The array positioning section  114  is a hole provided in the plane mounting support member  11 C. When the mounting support member  11 C is disposed on the electric wiring section  21 , the electric wiring section  21  is exposed through the array positioning section  114  without being covered by the mounting support member  11 C. Therefore, when the element array  14  is disposed in the array positioning section  114 , the electric connection between the element array  14  and the electric wiring section  21  can be achieved. 
   The wall surface of the array positioning section  114  is formed with an inclined surface  114   a . When the element array  114  is mounted, mechanical interference hardly occurs. Therefore, such a structure makes mounting easy. 
   In the above-described third embodiment, alignment marks are not used in positioning the element array  14 . However, alignment marks may be used for positioning the element array  14 . 
   (Effect of the Third Embodiment) 
   According to the third embodiment, the element array  14  and the optical part  13 A are directly positioned with respect to the mounting support member  11 C. Therefore, without an intermediate member such as a guide pin, positioning with high precision can be realized. 
   Fourth Embodiment 
   An optical transmission module according to the fourth embodiment of the invention has a plurality of guide pins provided in the side of an optical fiber receptacle provided in an optical part. The guide pin is used for the connection between the optical part and the optical fiber. 
     FIG. 6  is a sectional view illustrating the structure of the optical transmission module according to the fourth embodiment of the invention. 
   The optical transmission module  1  according to the fourth embodiment includes a mounting support member  11 A, a plurality of photoelectric elements  12 , the optical part  13 B, and the plurality of guide pins  15 . The mounting support member  11 A is provided on the electric wiring section  21  disposed on the substrate  2 . The mounting support member  11 A and the photoelectric elements  12  are the same as those of the first embodiment. 
   The optical part  13 B includes a plurality of lens sections  131 , the optical fiber receptacle section  132 , and a plurality of guide pin insertion holes (third concave portions)  133 . The optical part  13 B has a function of effectively delivering an optical signal emitted from the photoelectric element  12  to the optical fiber. 
   The lens section  131  and the optical fiber receptacle section  132  are the same as those of the optical part  13 A according to the first embodiment and have the same function. 
   The guide pin insertion hole  133  is provided at the upper surface of the optical part  13 B and at the side of the optical fiber receptacle section  132 . The guide pin  15  is inserted into the guide pin insertion hole  133 . 
   After being inserted into the guide pin insertion hole  133 , the guide pin  15  is used for connecting the optical fiber  4  (not shown) to the optical fiber receptacle section  132 . In this case, a fitting section  3   b  of the fiber holder  3 B holding the plurality of optical fibers  4  is fitted into the optical fiber receptacle  132 , and the guide pin  15  is inserted into a pin hole  3   a . When the guide pin  15  is inserted into a guide positioned at the side of the receptacle provided at one end of the optical fiber, the fitting section  3   b  is loosely fitted into the optical fiber receptacle section  132  and is positioned by the guide pin  15 . Therefore, the optical fiber  4  is easily inserted into the optical fiber receptacle section  132 , and the optical fiber  4  can be stably fixed. 
   (Effect of the Fourth Embodiment) 
   According to the fourth embodiment, the photoelectric elements  12  and the optical part  13 B are directly positioned with respect to the mounting support member  11 A, and the optical fiber  4  is positioned by the guide pin  15 . Therefore, positioning with high precision can be realized. 
   Fifth Embodiment 
     FIG. 7  is a sectional view illustrating the construction of an optical transmission module according to a fifth embodiment of the invention. Although the guide pin  15  is inserted into the guide pin insertion hole  133  provided in the optical part  13 B in the fourth embodiment, the optical part  13 B and the guide pin  15  are integrally formed in this embodiment. 
   The optical part  13 C composing the optical transmission module  1  shown in  FIG. 7  has a guide pin  134  provided in the side of an optical fiber receptacle section  132 . The guide pin  134  is formed of the same material as the optical part  13 C. The guide pin  134  is provided in advance when the optical part  13 C is formed. That is, the guide pin  134  and the optical part  13 C are integrally formed. 
   The guide pin  134  has the same function as the guide pin  15  shown in  FIG. 6 . The guide pin  134  is different from the guide pin  15  only in that the guide pin  134  and the optical part are integrally formed. 
   When the guide pin is used for fixing the optical fiber to the optical part, the optical fiber receptacle section may be omitted. 
   (Effect of the Fifth Embodiment) 
   According to the fifth embodiment, the photoelectric element  12  and the optical part  13 C are directly positioned with respect to the mounting support member  11 A, and the optical part  13 C and the optical fiber  4  are positioned by the guide pin  134 . Therefore, positioning with high precision can be realized. Further, the guide pin  134  and the optical part  13 C are integrally formed, which makes it easy to manufacture the optical part. 
   Sixth Embodiment 
     FIG. 8  is a sectional view illustrating the construction of an optical transmission module according to a sixth embodiment of the invention. In this embodiment, an optical part includes a guide pin but does not include an optical fiber receptacle section, compared with the fourth embodiment shown in  FIG. 6 . 
   The optical part  13 D includes the lens section  131  and the guide pin insertion hole  133 , but does not include an optical fiber receptacle section. However, the optical fiber can be fixed to the optical part  13 D using the guide pin  15 . 
   (Effect of the Sixth Embodiment) 
   According to the sixth embodiment, the photoelectric elements  12  and the optical part  13 D are directly positioned with respect to the mounting support member  11 A, and the optical section  13 D and the optical fiber  4  are positioned by the guide pin  15 . Therefore, without an intermediate member, positioning with high precision can be realized. Further, the optical part  13 D does not need to be provided with an optical fiber receptacle member, which makes it easy to manufacture the optical part  13 D. 
   Seventh Embodiment 
   An optical transmission module according to a seventh embodiment of the invention has a mirror surface provided in an optical part. The mirror surface reflects an optical signal emitted from a photoelectric element in a direction parallel to the substrate surface. 
     FIGS. 9A and 9B  are sectional views illustrating the structure of the optical transmission module according to the seventh embodiment of the invention.  FIG. 9A  shows the optical transmission module using only the mirror surface without a lens section, and  FIG. 9B  shows the optical transmission module using the lens section and the mirror surface. 
   (Optical Part of  FIG. 9A ) 
   The optical part  13 E shown in  FIG. 9A  has a concave portion (not shown) where a convex portion of the optical part positioning section  112  provided in the mounting support member  11 A is fitted, similar to other embodiments. Further the optical part  13 E has a mirror surface  135 A which bends an optical signal, which is diffusely emitted from the photoelectric element  12 , in a direction parallel to the substrate  2  and condenses light. 
   In  FIG. 9A , the optical signal emitted from the photoelectric element  12  proceeds while being diffused upward. If the optical signal proceeds into the optical part  13 E, the diffusion width thereof is suppressed in a relationship of a refractive index. 
   When the optical signal further proceeds so as to approach the mirror surface  135 A, the optical signal is reflected in the horizontal direction. At this time, since the surface mirror  135 A is a concave surface mirror, the optical signal which was being diffused proceeds while being converged. 
   When the optical signal proceeds outside the optical part  13 E, the optical signal approaches the optical fiber receptacle section  132  while being further converged due to a change in refractive index. Then, the optical signal is incident on the optical fiber held by a fiber holder (not shown) which is fitted into the optical fiber receptacle section  132 . 
   (Optical Part of  FIG. 9B ) 
   The optical part  13 F shown in  FIG. 9B  has a concave portion (not shown) which is fitted into the convex portion of the optical part positioning section  112  provided in the mounting support member  11 A, similar to other embodiments. Further, the optical part  13 F includes a lens section  131 A which changes an optical signal, diffusely emitted from the photoelectric element  12 , into parallel light; a mirror surface  135 B which bends the parallel light in a direction parallel to the substrate  2 ; and a lens section  131 B which condenses the parallel light reflected by the mirror surface  135 B. 
   In  FIG. 9B , the optical signal emitted from the photoelectric element  12  proceeds while being diffused upward. When the optical signal approaches the optical part  13 F, the optical signal is refracted by the lens section  131 A so as to become parallel light. The parallel light proceeds within the optical part  13 F. 
   If the parallel light further proceeds, the parallel light approaches the mirror surface  135 B and is reflected in the horizontal direction. At this time, since the mirror surface  135 B is a plane surface mirror, the parallel light is maintained as it is. 
   Further, when the optical signal proceeds outside the optical part  13 E, the optical signal is once again refracted by the lens section  131 B and then approaches the optical fiber receptacle section  132  while being converged. Then, the optical signal is incident on the optical fiber held by a fiber holder (not shown) which is fitted into the optical fiber receptacle section  132 . 
   (Effect of the Seventh Embodiment) 
   According to the seventh embodiment, the photoelectric element  12  and the optical part  13 E or  13 F are directly positioned with respect to the mounting support member  11 A, similar to the first embodiment. Therefore, without an intermediate member such as a guide pin, positioning with high precision can be realized. At the same time, the optical signal can be caused to proceed in the horizontal direction, without increasing the number of parts. 
   Other Embodiments 
   The present invention is not limited to the above-described embodiments, but modifications can be made without departing from the scope of the invention. Further, the components of the respective embodiments can be arbitrarily combined without departing from the scope of the invention. 
   In the above-described embodiments, the optical part is provided with the optical fiber receptacle section and the lens section. However, the optical part may be provided with only one of the optical fiber receptacle section and the lens section.

Technology Category: g