JP2007081261A - Optical transmission module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily connect an electric element in a module with a built-in optical element and a mounting part such as an optical waveguide, to provide a high degree of freedom in design, at a low cost, and to suppress the thermal effect of bonding and to achieve high speed. An optical transmission module having high reliability in operation is also provided.
A light receiving element 12 and a light emitting element 13 are mounted on a submount 16 installed on a metal stem 10 holding electrode pins 11A to 11F. Further, a relay electrode portion 20 is provided at a wire bonding relay position for connecting the light emitting element 13 with the electrode pin 11 </ b> A in the vicinity of the light emitting element 13 on the submount 16. The light emitting element 13 and the electrode pin 11A are connected to each other by bonding wires 14A and 14J with the relay electrode portion 20 as a relay position.
[Selection] Figure 1

Description

  The present invention relates to an optical transmission module that performs optical transmission with a configuration in which mounting components such as an optical element of a light emitting element and a light receiving element, and an optical waveguide are mounted.

  Conventionally, an optical transmission module has been used for optical communication, and an optical element such as a surface emitting laser (VCSEL) or a light receiving element such as a photodiode (PD) is optically coupled to an optical element. The optical waveguide is mounted so that optical communication can be performed bidirectionally via an optical fiber.

The optical waveguide is mounted upright in the optical axis direction of the optical element (see, for example, Patent Documents 1 and 2) or mounted in a state of being laid in a direction perpendicular to the optical axis direction of the optical element ( For example, see Patent Document 3).
JP 2004-221774 A JP 2003-329892 A JP 2004226694 A

  However, according to the conventional optical transmission module, the space between the mounting components has become narrow due to the miniaturization. For example, a bonding wire connecting the optical element and the electrode pin for external connection blocks the front of the light emitting element. It is easy for problems such as this to occur. In particular, since the optical waveguide is three-dimensional and large in size, the wiring path of the bonding wire is blocked by the optical waveguide, which may make wire bonding difficult or impossible. Further, when the configuration is given priority to the arrangement of the bonding wires, there is a problem that the shape of the optical transmission module is restricted and the degree of freedom in design is reduced or the manufacturing cost is increased.

  Accordingly, an object of the present invention is to provide a low-cost optical transmission module with a high degree of design freedom in which electrical connection within the module can be easily performed in a configuration incorporating an optical element and a mounting component such as an optical waveguide. There is to do.

  Another object of the present invention is to provide an optical transmission module that suppresses the thermal effects of bonding and has high reliability even in high-speed operation in a configuration in which an optical element and a mounting component such as an optical waveguide are incorporated. is there.

  In order to achieve the above object, one aspect of the present invention is a submount mounted on a mounted surface, an optical element mounted on the submount, and mounted on the mounted surface or the submount. An optical transmission comprising: a mounting component independent of the optical device; and a relay electrode that is formed at a position on the submount away from the mounting component and assists wiring to the optical device. Provide modules.

  According to the above-described optical transmission module, it is possible to perform wiring by bypassing the mounting component by the relay electrode that assists wiring, and electrical connection within the module can be easily performed. Further, even if the mounting component is mounted and then bonded to the relay electrode, the relay electrode is separated from the mounting component, so that the thermal influence on the mounting component during bonding can be suppressed.

  The mounting component can be wired through the relay electrode without interfering with the mounting component even when the mounting component is higher than the optical element.

  The relay terminal is located at a position on a path that bypasses the mounting component that connects the electrode of the optical element and a terminal connected to the electrode of the optical element, or at a corner of the upper surface of the rectangular submount. Can be formed. As a result, it is possible to suppress the thermal influence on the mounting component during bonding, and it is possible to perform wiring via the relay electrode without interfering with the mounting component.

  The mounting component is an optical waveguide attached to the submount. By mounting the optical waveguide and the optical element on the submount, it becomes easy to align the optical axes of the optical element and the optical waveguide, and miniaturization is facilitated.

  The optical waveguide is easily affected by heat because it is a polymer optical waveguide, but a relay electrode for assisting wiring is provided at a remote position, and detour wiring is performed through the relay electrode. The polymer optical waveguide has no thermal influence.

  The optical element is a planar optical element having a light receiving part or a light emitting part, and the optical waveguide can be erected on the light receiving part or the light emitting part of the optical element. By using a surface optical element as the optical element, a structure in which an optical waveguide is erected on the surface light emitting element can be easily adopted.

  By connecting a plurality of bonding wires to the relay electrode, it is possible to easily perform detour wiring with respect to the mounted component.

  The relay electrode has a wiring pattern shape with a predetermined length, so that the length of the bonding wire connected to the electrode can be shortened, and the wire connection part and the wire are prevented from being disconnected by vibration or the like. be able to.

  Even if the mounting component is an electronic component mounted on the submount, high-density mounting is possible by arranging the mounting component in the vicinity of the optical element. Further, even if the mounting component is an electronic component mounted on the mounting surface, detour wiring using an electrode that assists wiring can be applied, and interference with the electronic component due to wire bonding can be avoided. . Examples of such electronic components include a light receiving element amplification IC, a capacitor, and a light emitting element driving IC.

  The submount has a base material made of silicon, and the electrode is formed on the surface of the base material, so that it is possible to form a submount with a complicated structure and the electrode is easily formed. become.

  According to the present invention, in a configuration in which an optical element and a mounting component such as an optical waveguide are built in, an electrical transmission module can be easily connected, a design freedom is high, and a low-cost optical transmission module is provided. Can do.

  In addition, in a configuration in which an optical element and a mounting component such as an optical waveguide are built in, it is possible to provide an optical transmission module that suppresses the thermal effect of bonding and has high reliability even at high speed operation.

[First Embodiment]
FIG. 1 shows an optical transmission module according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line AA in FIG. FIG. 1 shows a mounting component on a metal stem.

  The optical transmission module 1 includes a metal stem 10 whose upper surface is a mounting surface, a light receiving element 12 and a light emitting element 13 disposed on the metal stem 10, a light receiving part 12 a of the light receiving element 12, and a light emitting part of the light emitting element 13. An optical waveguide 15 as a mounting component that is optically coupled to 13a, a light receiving element 12, a light emitting element 13, and a submount 16 for positioning the optical waveguide 15, and a metal stem 10 are provided to amplify an output signal of the light receiving element 12. IC 19 to be provided.

  The optical transmission module 1 holds a plurality of electrode pins 11 (11A to 11F) held by an insulator 21 on a metal stem 10, and a bonding wire 14 between the light receiving element 12, the light emitting element 13, and the IC 19 is used. (14A-14J). Further, a relay electrode portion 20 that assists in wire bonding to the light emitting element 1 is provided on the submount 16, and the light emitting element 13 and the electrode pin 11F are detoured and connected by bonding wires 14A and 14J.

  Furthermore, the optical transmission module 1 includes a metal cap 17 that has an opening 17a on the ceiling surface and seals each member on the metal stem 10, a transmission window 18 that seals the opening 17a, and a transmission window 18. A refractive index matching agent 24 disposed between the optical waveguides 15 and a coupler member 30 to which the optical fiber 2 is connected and attached to the cap 17 are provided.

  The metal stem 10 is processed into a disk shape with a metal such as copper or copper alloy capable of wire bonding for ground connection to the surface.

  Of the electrode pins 11A to 11F, the electrode pins 11A to 11C are for reception, the electrode pins 11A and 11B are for differential signals, and the electrode pin 11C is for ground. The electrode pins 11D to 11F are for transmission, the electrode pin 11D is for power supply, and the electrode pins 11E and 11F are for ground.

  The light receiving element 12 is a planar optical element having a light receiving portion 12a for receiving an optical signal on the upper surface, a mounting surface mounted on the metal stem 10 on the lower surface, and two electrodes on the upper surface. A PIN photodiode can be used.

  The light emitting element 13 is a planar optical element having a light emitting portion 13a that emits an optical signal on the upper surface, a mounting surface mounted on the metal stem 10 on the lower surface, and electrodes on the upper and lower surfaces, for example, a wavelength of 850 nm. VCSELs can be used. Note that a light-emitting element having two electrodes on the upper surface may be used.

  The optical waveguide 15 is, for example, a polymer optical waveguide, and is formed with a toroidal light guide portion 15a made of a core material such as acrylic resin, epoxy resin, or polyimide resin, and around the light guide portion 15a than the core material. A clad made of a fluorine-based polymer or the like having a low refractive index is formed. Such an optical waveguide 15 can be produced, for example, as disclosed in Japanese Patent Application Laid-Open No. 2004-226941. That is, a recess formed on the surface of a mold made of a curable resin is filled with an ultraviolet curable resin or a core-forming curable resin made of a thermosetting resin, and a clad film base material is bonded to the mold surface, After the forming curable resin is cured to form a core, the mold is peeled off, and a clad layer is formed on the core forming surface side of the clad film base material, thereby producing a polymer optical waveguide. In addition, the pattern of the light guide part 15a is not limited to the above-mentioned T shape, and other patterns such as a Y shape can be used according to the combination of optical elements.

  The cap 17 is formed in a can shape with a metal such as copper, copper alloy, aluminum, aluminum alloy or the like in order to reduce noise from the outside, and the lower end surface is electrically conductive with the metal stem 10 as shown in FIG. It is fixed with an adhesive or the like.

  The transmission window 18 is made of a plastic material such as polymethyl methacrylate, polycarbonate, and amorphous polyolefin, or a transparent material such as inorganic glass.

  The IC 19 incorporates a circuit for amplifying an output signal from the light receiving element 12, has a plurality of electrodes on the upper surface, and is disposed adjacent to the light receiving element 12.

  The refractive index matching agent 24 has a refractive index comparable to that of the optical waveguide 15 and the transmission window 18 and is made of a transparent material. For example, a silicone resin, an ultraviolet curable adhesive, or the like is used. Can do.

  The coupler member 30 is made, for example, by molding a transparent resin, and is detachably attached to the cap 17. The coupler member 30 includes a housing portion 31 fitted on the cap 17, a lens portion 32 formed at the center of the housing portion 31, and a cylindrical shape formed on the upper portion of the housing portion 31. The optical fiber insertion part 33 in which 2 is inserted, and the collar part 34 provided in the outer periphery of the optical fiber insertion part 33 are provided.

(Submount configuration)
FIG. 3 shows the configuration of the submount. The submount 16 includes a main body 16a made of an insulating material such as Si, and a through hole 16d provided at the center of the main body 16a and corresponding to the outer shape in which the optical waveguide 15 is mounted on the light receiving element 12 and the light emitting element 13. is doing. The through hole 16 d has a light receiving element mounting portion 16 b for positioning the light receiving element 12 and a light emitting element mounting portion 16 c for positioning the light emitting element 13. Further, the relay electrode portion 20 described above is formed in the vicinity of the optical element mounting portion 16 c on the upper surface of the submount 16.

  The relay electrode portion 20 is a pad formed of an Au thin film or the like, and the shape thereof may be a square shape or a round shape. Further, the relay electrode unit 20 is located away from the optical waveguide 15, that is, on a path that bypasses the optical waveguide 15 that connects the electrode of the light emitting element 13 and the electrode pin 11 </ b> F connected to the electrode of the light emitting element 13. Formed in position. In this embodiment, the submount 16 is formed at the corner of the rectangular upper surface.

(Assembling the optical transmission module)
First, the IC 3 and the submount 16 are mounted at predetermined positions on the metal stem 10. The submount 16 is fixed using an adhesive or the like. Next, the light receiving element 12 and the light emitting element 13 are positioned and fixed to the light receiving element mounting portion 16b and the light emitting element mounting portion 16c of the submount 16, respectively. At this time, the electrode on the lower surface of the light emitting element 12 contacts the upper surface of the metal stem 10 and is grounded.

  Next, the IC 19 and predetermined positions on the light receiving element 12 and the metal stem 10 are connected by bonding wires 14F, 14G, 14H, and 14I, and the IC 19 and the electrode pins 11A, 11B, and 11D are connected by bonding wires 14D, 14E, and 14B. The electrodes of the light emitting element 13 and the relay electrode 20 are connected by a bonding wire 14J, the relay electrode portion 20 and the electrode pin 11F are connected by a bonding wire 14A, and the electrode pin 11C and the upper surface of the metal stem 10 are bonded. Connect with wire 14C.

  Next, the optical waveguide 15 is positioned and fixed in the portion of the through hole 16 d of the submount 16. Further, the refractive index matching agent 24 is interposed on the optical waveguide 15, and in this state, the cap 17 to which the transmission window 18 is previously attached is fixed on the metal stem 10.

  The optical transmission / reception module 1 is mounted by penetrating the electrode pins 11A to 11F of the optical transmission module 1 thus manufactured through connection holes (through holes) formed in the circuit board. Next, the coupler member 30 having the lens portion 32 and the optical fiber insertion portion 33 is fitted into the cap 17, the optical fiber 2 is held by the optical fiber insertion portion 33, the coupler member 30 is positioned, and then the coupler member 30 is The cap 17 is fixed with an epoxy resin or the like. In this way, the optical transmission device is manufactured.

(Operation of optical transmission equipment)
When an optical signal is sent from the optical fiber 2, the optical signal enters the light guide portion 15 a of the optical waveguide 15 through the lens portion 32 of the coupler member 30, the transmission window 18, and the refractive index matching agent 24. To do. The optical signal from the light guide unit 15 a enters the light receiving unit 12 a of the light receiving element 12 and is photoelectrically converted by the light receiving element 12. This electric signal is amplified by the IC 19 and output to the circuit board via the electrode pins 11A and 11B.

  On the other hand, when a drive signal is input from the circuit board to the electrode pin 11F, the light emitting element 13 is driven and an optical signal is output from the light emitting unit 13a. This optical signal enters the light guide portion 15 a of the optical waveguide 15, reaches the refractive index matching agent 24, and is further sent to the optical fiber 2 via the transmission window 18 and the lens portion 32. As described above, single-core bidirectional communication is performed.

(Effects of the first embodiment)
According to the first embodiment, the following effects are obtained.
(A) The relay electrode portion 20 is provided on the submount 16, and the light emitting element 13 and the electrode pin 11 </ b> F are detoured by the bonding wires 14 </ b> A and 14 </ b> J via the relay electrode portion 20, thereby making an optical connection. Even if the waveguide 15 is mounted in a vertical position, wire bonding can be performed without being obstructed by the optical waveguide 15. Further, there is no possibility that the wire and the optical waveguide 15 come into contact with each other and the wire is broken by the vibration of the optical waveguide 15.
(B) Since the optical waveguide 15 can be mounted after wire bonding, it is possible to prevent the light guide portion 15a of the optical waveguide 15 from being damaged by heat generated during bonding.
(C) Since the wire length can be shortened by the relay electrode 20, breakage of the wire and the wire connecting portion due to vibration or the like can be prevented, and high-frequency characteristics can be improved.
(D) By providing the relay electrode portion 20 for connection between the light emitting element 13 and the electrode pin 11F, the shape of the optical transmission module 1 is not restricted, and the degree of freedom in design is improved. . In particular, the provision of the relay electrode portion 20 on the submount 16 makes it difficult to receive restrictions.
(E) Since the relay connection between the light emitting element 13 and the electrode pin 11 only needs to be provided with the relay electrode section 20, it is possible to prevent an increase in the number of parts and to facilitate the manufacture of the optical transmission module 1. Cost reduction is possible.
(F) In addition to the light receiving element 12 and the light emitting element 13 on the submount 16, the optical waveguide 15 is mounted as another mounting component such as an electronic component, whereby high-density mounting can be achieved.
(G) Since the submount 16 is made of Si material, a complicated structure can be formed.

  In the above embodiment, the optical waveguide 15 is mounted after bonding the electrode of the light emitting element 13 and the relay electrode 20, and the relay electrode portion 20 and the electrode pin 11F. However, the order of bonding and mounting components is limited. Not. For example, after the electrode of the light emitting element 13 and the relay electrode 20 are bonded, the optical waveguide 15 is mounted, and the relay electrode portion 20 and the electrode pin 11F can be bonded. Since the relay electrode 20 is formed at a position away from the optical waveguide 15, it is possible to suppress the thermal effect on the optical waveguide 15 during bonding.

(Second Embodiment)
FIG. 4 shows an optical transmission module according to the second embodiment of the present invention. In the present embodiment, the shape of the relay electrode portion 20 is changed to a predetermined length wiring pattern shape in the first embodiment, and other configurations are the same as those in the first embodiment.

  The relay electrode unit 20 is provided in parallel with the pin rows of the electrode pins 11D to 11F, bypassing the optical waveguide 15 with copper foil or the like. The relay electrode unit 20 includes a conductive pattern 20a slightly longer than the thickness dimension of the optical waveguide 15, and electrodes 20b and 20c formed at both ends of the conductive pattern 20a.

  The electrode 20b is provided adjacent to the light emitting element 13, and is connected to the electrode of the light emitting element 13 by a bonding wire 14J. The electrode 20c is provided at a position close to the electrode pin 11F, and is connected to the electrode pin 11F by a bonding wire 14A.

According to the second embodiment, the following effects are obtained.
(A) By providing the relay electrode portion 20 in the shape of the wiring pattern on the submount 16, wiring bypassing the optical waveguide 15 that is a mounting component is possible, and mounting properties and high-frequency characteristics can be improved. it can. Further, similarly to the first embodiment, interference with the optical waveguide 15 at the time of bonding can be prevented, and the thermal influence on the optical waveguide 15 at the time of bonding can be suppressed.
(B) Since the electrode 20c of the relay electrode portion 20 is disposed in the vicinity of the electrode pin 11F, the length of the bonding wire 14A can be minimized, and the bonding wire 14A can be compared with the first embodiment. And contact with other members such as the metal stem 10 and the electrode pin 11E can be avoided.
(C) Since the relay electrode portion 20 is formed in a wiring pattern shape, the wire length can be made shorter than that in the first embodiment, so that the reliability can be further improved.
(D) Since the relay electrode portion 20 is formed in a wiring pattern shape, more complicated wiring is possible, and the reliability can be improved as compared with the case where the bonding wire is lengthened.

[Third Embodiment]
FIG. 5 shows an optical transmission module according to the third embodiment of the present invention. FIG. 6 shows the configuration on the submount of the optical transmission module of FIG.

  In this embodiment, in the second embodiment, the optical waveguide 15 is arranged parallel to the metal stem 10, that is, horizontally arranged, and the metal stem 40 and the submount having a shape matched to the horizontal arrangement of the optical waveguide 15 are used. 50, and further includes a second light emitting element instead of the light receiving element 12, and the other configuration is the same as that of the second embodiment.

  As shown in FIGS. 5 and 6, the optical waveguide 15 includes light guide portions 151 and 152 that are optically coupled to the light emitting portions 13a of the first and second light emitting elements 13A and 13B, and first and second light guides. The light emitting elements 13A and 13B of the light emitting elements 13a and 13B are mounted on the submount 50 in a state of being provided with a 45 degree mirror 153 for allowing the light from the light emitting parts 13a to enter the light guide parts 151 and 152.

  The light guide parts 151 and 152 are made of the same core material as the light guide part 15a of the first embodiment, and a clad made of a material having a refractive index smaller than that of the core material is formed around the light guide parts 151 and 152.

  The 45-degree mirror 153 is formed by cutting one end of the optical waveguide 15 at 45 degrees, and a reflective film is formed on the cut surface by silver vapor deposition or the like.

  The metal stem 40 is formed in a square shape using the same material as that of the metal stem 10, and four electrode pins 22 </ b> A to 22 </ b> D and 22 </ b> E to 22 </ b> H are arranged in the vicinity of two opposing sides, and light is transmitted between the pin rows. A waveguide 15 is provided. Furthermore, in order to protect the first and second light emitting elements 13A and 13B and other mounting components, a cap (not shown) is attached to the metal stem 40 after the wiring is completed.

  The submount 50 is made of the same material as that of the submount 16, and has a recess 50a for positioning and mounting the first and second light emitting elements 13A and 13B and the optical waveguide 15 as shown in FIG. At the same time, it has a width that can project the end face of the optical waveguide 15.

  Further, in the submount 50, relay electrode portions 20 </ b> A to 20 </ b> D each including a conductive pattern 20 a and electrodes 20 b and 20 c are formed along two sides of the optical waveguide 15. The relay electrode part 20A is for connecting the terminal of the first light emitting element 13A and the electrode pin 22D, and the relay electrode part 20B is for connecting the terminal of the first light emitting element 13A and the electrode pin 22C, and the electrode part for relaying 20C is for connecting the electrode pin 22H of the terminal of the second light emitting element 13B, and the relay electrode portion 20D is for connecting the terminal of the second light emitting element 13B and the electrode pin 22G.

  FIG. 7 shows the arrangement of optical waveguides and light emitting elements. Here, the arrangement of the first light emitting element 13A and the optical waveguide 15 is shown, but the second light emitting element 13B has the same arrangement. The 45-degree mirror 153 of the optical waveguide 15 is positioned above the light-emitting portion 13a of the first light-emitting element 13A, and the output light of the light-emitting portion 13a is reflected by the 45-degree mirror 153 as indicated by the arrow C, and the light guide portion 151 is incident.

(Assembling the optical transmission module)
First, the submount 50 is positioned and fixed at a predetermined position on the metal stem 40, and the first and second light emitting elements 13A and 13B are mounted at the predetermined position of the submount 50. Next, the electrodes 20c of the relay electrode portions 20A to 20D and the electrode pins 22C, 22D, 22G, and 22H are connected by bonding wires 23A to 23D. Further, the first light emitting element 13A and the respective electrodes 20b of the relay electrode portions 20A and 20B are connected by bonding wires 23E and 23H, and the second light emitting element 13B and the relay electrode portions 20C and 20D are bonded by the bonding wire 23F. , 23G.

  Next, the optical waveguide 15 is mounted on the submount 50 so that the 45 degree mirror 153 overlaps the light emitting portion 13a. Thus, the optical transmission module 1 is completed. An optical fiber is connected to the end faces of the light guides 151 and 152 via a coupler (not shown).

  According to the third embodiment, the relay electrode portions 20A to 20D are provided on the submount 50, and the light emitting elements 13A and 13B are formed by the bonding wires 23A to 23D, 23E, and 23H via the relay electrode portions 20A to 20D. By connecting the electrode pins 22C, 22D, 22G, and 22H by electrical connection, wire bonding can be performed without being obstructed by the optical waveguide 15 even when the optical waveguide 15 is mounted in a horizontal position. The optical waveguide 15 can be mounted after bonding.

[Other embodiments]
The present invention is not limited to the above embodiments, and various modifications can be made without departing from or changing the technical idea of the present invention. For example, in the first and second embodiments, a light receiving element and a light emitting element are used, and in the third embodiment, two light emitting elements and a light emitting element are used. However, two light receiving elements may be used. A single light emitting element or light receiving element may be used, and the number and combination of optical elements are arbitrary.

  In the first and second embodiments, the amplification IC of the light receiving element is arranged in the module. However, the amplification IC may be arranged on the circuit board side without being arranged in the module. In addition to the light receiving element and the light emitting element, a driving IC for the light emitting element may be disposed in the module, and the light emitting element, the light receiving element, the amplification IC, and the driving IC may be disposed in the module.

1 is a plan view showing an optical transmission module according to a first embodiment of the present invention. It is the sectional view on the AA line of FIG. It is a top view which shows the structure of a submount. It is a top view which shows the optical transmission module which concerns on the 2nd Embodiment of this invention. It is a top view which shows the optical transmission module which concerns on the 3rd Embodiment of this invention. It is a perspective view which shows the structure on the submount of the optical transmission module of FIG. It is sectional drawing which shows arrangement | positioning of an optical waveguide and a light emitting element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical transmission module 2 Optical fiber 10 Metal stem 11A-11F Electrode pin 12 Light receiving element 12a Light receiving part 13 Light emitting element 13A, 13B Light emitting element 13a Light emitting part 14A-14J Bonding wire 15 Optical waveguide 15a Light guide part 16 Submount 16a Main body 16b Light receiving element mounting portion 16c Light emitting element mounting portion 16d Through hole 17 Cap 17a Opening 18 Transmission window 19 IC
20, 20A to 20D Relay electrode portion 20a Conductive patterns 20b and 20c Electrode 21 Insulators 22A to 22H Electrode pins 23A to 23H Bonding wire 24 Refractive index matching agent 30 Coupler member 31 Housing portion 32 Lens portion 33 Optical fiber insertion portion 34 Part 40 metal stem 50 submount 50a recess 151, 152 light guide part 153 45 degree mirror

Claims (12)

A submount mounted on the mounting surface;
An optical element attached to the submount;
A mounting component mounted on the mounting surface or the submount and independent of the optical element;
An optical transmission module comprising: a relay electrode which is formed at a position on the submount away from the mounting component and assists wiring to the optical element.   The optical transmission module according to claim 1, wherein the mounting component is higher than the optical element.   2. The relay electrode according to claim 1, wherein the relay electrode is formed at a position on a path that bypasses the mounting component that connects the electrode of the optical element and a terminal connected to the electrode of the optical element. Optical transmission module. The submount has a rectangular upper surface;
The optical transmission module according to claim 1, wherein the relay electrode is formed at a corner of the upper surface of the submount.   The optical transmission module according to claim 1, wherein the mounting component is an optical waveguide attached to the submount.   The optical transmission module according to claim 5, wherein the optical waveguide is a polymer optical waveguide. The optical element is a planar optical element having a light receiving part or a light emitting part,
The optical transmission module according to claim 5, wherein the optical waveguide is erected on the light receiving portion or the light emitting portion of the optical element.   The optical transmission module according to claim 1, wherein a plurality of bonding wires are connected to the relay electrode.   The optical transmission module according to claim 1, wherein the relay electrode has a wiring pattern shape having a predetermined length.   The optical transmission module according to claim 1, wherein the mounting component is an electronic component mounted on the submount.   The optical transmission module according to claim 1, wherein the mounting component is an electronic component mounted on the mounting surface. The submount has a base material made of silicon,
The optical transmission module according to claim 1, wherein the relay electrode is formed on a surface of the base material.