JP2010161146A - Optical transmitting module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical transmitting module in which a PD for monitoring is provided so that a rear outgoing light of an LD can be efficiently received and the length of a wire connecting an electrode pad of an LD carrier with an electrode pad of a circuit board is reduced. <P>SOLUTION: In this optical transmitting module, an LD carrier 21 has a slope 21c between a mounting surface 21a of an LD 14 and an installation surface 21b of an electrode pad, the installation surface 21b of an electrode pad and an electrode pad face of the circuit board 17 are positioned on the same plane, and a PD 18 for monitoring is arranged so as to receive a rear outgoing light of an LD 14. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical transmission module that transmits an optical signal.

  In high-speed small-sized optical transceivers based on standards such as XFP (10 Gigabit Form-factor Pluggable) and SFP (Small Form-factor Pluggable), the external shape dimensions of a package that accommodates an optical module are defined by industry standards. Therefore, the size of an optical transmission module (TOSA: Transmitting Optical Sub-Assembly) accommodated in the package is also limited.

  In order to house the optical transmission module in such a package, the PD (Photo Diode) for monitoring the optical output of the LD (Laser Diode: light emitting element), the condenser lens, and the LD that constitutes the optical transmission module. : Light receiving element), heat dissipating module and other components are arranged efficiently to reduce the size of the optical transmission module. An optical transmission module reduced in size as described above is disclosed in Patent Document 1, for example.

  Here, an outline of a conventional optical transmission module will be described with reference to FIG. As shown in FIG. 6A, in the optical transmission module 10, a thermoelectric module 12 is disposed in a package 11, and an LD carrier member (hereinafter referred to as an LD carrier) having good thermal conductivity on the thermoelectric module 12. The LD 14 is mounted via 13.

  The signal light transmitted from the LD 14 is incident on an optical fiber (not shown) in front of the package 11 through a lens 15 mounted on the thermoelectric module 12. The thermoelectric module (TEC) 12 includes a first plate 12b on the heat absorption side of the thermoelectric conversion element 12a, and a second plate 12c on the exhaust heat side. An LD carrier 13 is mounted on the first plate 12b on the side. Heat generated by the LD 14 mounted on the LD carrier 13 is exhausted to the outside by the thermoelectric module 12 via the package 11.

  Further, a multilayer circuit board 17 having lead terminals 16 is mounted behind the package 11 (opposite to the side on which the lens 15 is disposed). A monitoring PD 18 is mounted on the circuit board 17 via a PD carrier 19. As shown in the drawing, the LD 14 and the monitor PD 18 are arranged to face each other. The circuit board 17 is composed of a multilayer substrate such as a first ceramic substrate 17a and a second ceramic substrate 17b, and is fixed to the package 11 by an insulating block 17c. Wiring conductors and electrode pads are formed on the ceramic substrates 17a and 17b, respectively, and are used for electrical connection between the thermoelectric module 12, the LD 14, the monitoring PD 18 and an external device.

  The LD 14 is electrically connected to an electrode pad formed on a wiring conductor on the LD carrier 13, and the electrode pad and the electrode pad of the circuit board 17 are electrically connected by a wiring wire 20 for driving the LD. . A thermistor (not shown) for detecting the temperature of the LD 14 is also electrically connected via a wire.

JP 2008-166730 A

  By the way, from the viewpoint of optical coupling efficiency and cost, the rear outgoing light P1 of the LD 14 can be directly incident on the monitor PD 18 without being refracted, reflected, or collected, and the rear outgoing light can be received efficiently. The monitor PD 18 needs to be disposed on the optical path of the backward emission light.

  Further, when the LD 14 is driven at a high speed, it is necessary to reduce the length of the wire as much as possible in order to reduce the influence of the parasitic inductance in the LD driving wiring wire 20 on the optical output waveform as much as possible and prevent the deterioration of the high frequency characteristics. There is. When the length of the wiring wire 20 is shortened, the electrode pad of the LD carrier 13 to which the wiring wire 20 is connected and the electrode pad of the circuit board 17 are arranged on the same plane (at the same level) as shown by a line P2. In addition, it is necessary to shorten the distance between both electrode pad portions.

  However, as described above, when both electrode pads are arranged on the same plane, the backward emission light P1 of the LD 14 cannot be efficiently received by the light receiving surface of the monitoring PD 18. As a result, the amount of light incident on the monitor PD 18 decreases, and the monitor current output by the monitor PD 18 decreases.

  Therefore, as shown in FIG. 6B, if the LD mounting surface of the LD carrier 13 is raised, the rear emission light P1 of the LD 14 is directly incident on the monitoring PD 18, and the monitoring PD 18 efficiently uses the rear emission light. The light can be received well. However, when the position of the LD mounting surface of the LD carrier 13 is aligned with the light receiving surface of the monitoring PD 18 as described above, the position of the electrode pad formed on the same surface as the LD mounting surface is more than the electrode pad surface of the circuit board. Get higher. For this reason, a step H is generated between the electrode pads, the length of the wiring wire 20 is increased, the parasitic inductance is increased, and the high frequency characteristics are deteriorated.

  The present invention has been made in view of such a situation, and a monitor PD is disposed so as to efficiently receive light emitted backward from the LD, and an electrode pad of the LD carrier and an electrode pad of the circuit board are provided. An object of the present invention is to provide an optical transmission module in which the length of a connected wire is shortened.

An optical transmission module according to the present invention includes a carrier member on which a light emitting element is mounted and provided with an electrode pad of the light emitting element, and a light receiving element for monitoring the light output of the light emitting element, and a circuit provided with a wiring conductor and an electrode pad The electrode pad of the carrier member and the electrode pad of the circuit board are connected by a wire.
The carrier member has a step between the mounting surface of the light emitting element and the installation surface of the electrode pad, the installation surface of the electrode pad and the electrode pad surface of the circuit board are located on the same plane, It arrange | positions so that the back emitted light of a light emitting element may be received. Further, the step of the carrier member is formed by an inclined surface.

  According to the present invention, since the monitoring PD can be disposed on the optical path of the backward emission light so that the backward emission light of the LD can be received with high efficiency, the monitoring PD can accurately output the optical output of the LD, Can be monitored. Further, since the length of the wire connecting the electrode pad of the LD carrier and the electrode pad of the circuit board can be shortened, the parasitic inductance in the wire can be reduced and the deterioration of the high frequency characteristics can be prevented.

It is front sectional drawing of the optical transmission module which concerns on this invention. It is sectional drawing from the upper direction of an optical transmission module. It is a detailed view of the LD carrier according to the present invention. It is a detailed view of a PD carrier. It is the schematic explaining the connection relation of a lead terminal. It is a figure for demonstrating an example of the conventional optical transmission module.

  The present invention will be described with reference to FIGS. FIG. 1 is a front sectional view of an optical transmission module according to the present invention, and FIG. 2 is a sectional view from above of the optical transmission module according to the present invention. FIG. 3 is a diagram illustrating details of the LD carrier, and FIG. 4 is a diagram illustrating details of the PD carrier. FIG. 5 is a schematic diagram for explaining the connection relationship of the lead terminals.

  As shown in FIG. 1, the optical transmission module 1 according to the present invention is configured by disposing a thermoelectric module 12 in a package 11 as described in FIG. 6. The thermoelectric module 12 includes a first plate 12b on the heat absorption side of the thermoelectric conversion element 12a and a second plate 12c on the exhaust heat side. Is mounted with an LD carrier 21. The LD 14 is mounted on the mounting surface 21 a of the LD carrier 21, and heat generated by the LD 14 is exhausted to the outside by the thermoelectric module 12 through the package 11.

  The signal light transmitted from the LD 14 is incident on an optical fiber (not shown) in front of the package 11 through a lens 15 mounted on the thermoelectric module 12. Further, a circuit board 17 having lead terminals 16 is mounted behind the package 11. A monitoring PD 18 is mounted on the circuit board 17 via a PD carrier 19. As shown in the drawing, the light emitting portion of the backward emission light P1 of the LD 14 and the light receiving surface of the monitoring PD 18 are opposed to each other. The circuit board 17 is composed of a multilayer substrate such as a first ceramic substrate 17a and a second ceramic substrate 17b, and is fixed to the package 11 by an insulating block 17c. Electrode pads and wiring conductors (see FIG. 2) are formed on the ceramic substrates 17a and 17b, respectively, and are used for electrical connection between the thermoelectric module 12, the LD 14, and the monitoring PD 18 and an external device. A via hole 17d is formed in the first ceramic substrate 17a.

  Next, the structure of the LD carrier 21 according to the present invention will be described. On the LD carrier 21, an LD mounting surface 21a for mounting the LD 14 and an installation surface 21b on which the electrode pads 23 of the LD 14 are provided are formed. The mounting surface 21b of the LD mounting surface 21a and the electrode pad 23 has a step L, and this step is formed by, for example, an inclined surface 21c. The height position of the LD mounting surface 21a is set so that the monitoring PD 18 can efficiently receive the rear emission light P1 of the LD 14. Further, the height position of the installation surface 21b of the electrode pad 23 is set so as to be positioned on the same plane as the electrode pad installation surface 24 of the second ceramic substrate 17b of the circuit board 17 as indicated by the line P3. Is done.

  Next, details of the LD carrier 21 will be described with reference to FIGS. FIG. 2 is a diagram seen from above the optical transmission module. 3A is a view seen from above the LD carrier 21, and FIG. 3B is a front view of the LD carrier 21. The electrode pad 23 provided on the installation surface 21b of the LD carrier 21 includes an LD cathode electrode pad 23a and an LD anode electrode pad 23b. Both electrode pads (23a, 23b) are formed at the tip end portions (on the monitoring PD 18 side) of the LD cathode wiring conductor 22a and the LD anode wiring conductor 22b constituting the wiring conductor of the LD.

  As shown in FIG. 2, the LD cathode electrode pad 23a and the LD cathode electrode pad 24a on the electrode pad mounting surface 24 of the circuit board 17 are electrically connected via a wiring wire 25a. 23b and the LD anode electrode pad 24b are electrically connected via a wiring wire 25b. The LD cathode electrode pad 24a and the LD anode electrode pad 24b on the installation surface 24 of the circuit board 17 are arranged at the same position as the LD cathode electrode pad 23a and the LD anode electrode pad 23b on the installation surface 21b of the LD carrier 21. And located on the same plane (see line P3 in FIG. 1). The wiring wire 20 shown in FIG. 1 is the same as the wiring wires 25a and 25b. The anode terminal 14a of the LD 14 is connected to the LD anode wiring conductor 22b by a wiring wire 26a.

In this way, by forming the upper surface of the LD carrier 21 with the LD mounting surface 21a having a step and the electrode pad installation surface 21bb, the LD 14 can efficiently receive the light emitted backward from the LD 14 by the monitoring PD 18. Can be arranged. Further, by forming the step with the inclined surface 21c, the light emitted backward from the LD 14 is not blocked.
Further, since the electrode pad installation surface 21b of the LD carrier 21 and the electrode pad installation surface 24 of the circuit board 17 are on the same plane, the length of the wiring wire 25a for the LD cathode and the wiring wire 25b for the LD anode is long. The length can be shortened. As a result, the parasitic inductance of the wiring wire can be suppressed and a good optical output waveform can be obtained, which can cope with higher speed transmission.

  A thermistor 27 for monitoring the temperature of the LD 14 is disposed on the LD carrier 21. The connection terminal (not shown) of the thermistor 27 is connected to the thermistor wiring conductor 22c, and the thermistor electrode pad 23c formed at the tip of the thermistor wiring conductor 22c and the thermistor electrode pad 24c of the circuit board Are electrically connected via a wiring wire 25c. The connection terminal 27a of the thermistor 27 is connected to the thermistor wiring conductor 22c by the wiring wire 26b.

  The first plate-like body 12b on the heat absorption side of the thermoelectric module 12 (see FIG. 1) is provided with a TEC wiring conductor 22d for supplying power to the thermoelectric conversion element 12a. The TEC electrode pad 23d of the TEC wiring conductor 22d and the TEC electrode pad 24d of the circuit board 17 are electrically connected via the wiring wire 25d.

  In addition, although the example which formed the level | step difference of LD carrier 21 with the inclined surface 21c was shown, step shape (step shape) may be sufficient. In this case, wiring metallization is applied to the side surface of the step, or vias are provided with multiple carriers. In this embodiment, the LD carrier 21 is mounted on the first plate 12b. However, if there is no limitation on the mounting area, the LD carrier 21 is not particularly required to be mounted on the first plate 12b. Good. The LD carrier 21 can be made of a material having high thermal conductivity, for example, aluminum nitride.

  Next, details of the monitor PD 18 will be described with reference to FIG. 4A is a side view of the PD carrier 19 viewed from the lens 15 direction, and FIG. 4B is a diagram viewed from the lower side of the PD carrier 19. On the side and bottom surfaces of the PD carrier 19, a cathode wiring conductor 22e electrically connected to the cathode terminal 18a of the monitoring PD 18 via a wiring wire 26c is provided, and the cathode wiring conductor 22e has a cathode electrode pad 23e. Is formed. The cathode electrode pad 23e is connected to the wiring conductor 28e of the circuit board 17 through the via hole 17e (see FIG. 2). Further, an anode electrode pad 23f is formed on the anode wiring conductor 22f of the monitor PD 18, and this anode electrode pad 23f is connected to the wiring conductor 28f of the circuit board 17 through the via hole 17d (see FIG. 2). Connect with.

  As shown in FIG. 2, the plurality of lead terminals (16 a to 16 f) are provided so as to be electrically connected to end portions of the wiring conductors (28 a to 28 f) formed on the circuit board 17. The wiring conductor is formed on the second ceramic substrate 17b shown in FIG.

As shown in FIGS. 2 and 5, the thermistor lead terminals 16c ₁ and 16c ₂ are connected to the thermistor 27 through wiring conductors 28c ₁ and 28c _{2 and the} like. The PD lead terminals 16e and 16f are connected to the monitor PD 18 via the wiring conductors 28e and 28f. The LD lead terminals 16a and 16b are connected to the LD 14 via the wiring conductors 28a and 28b. The TEC terminals 16d ₁ and 16d ₂ are connected to the thermoelectric conversion element 12a via the wiring conductors 28d ₁ and 28d _{2 and the} like.

DESCRIPTION OF SYMBOLS 1,10,10 '... Optical transmission module, 11 ... Package, 12 ... Thermoelectric module (TEC), 12a ... Thermoelectric conversion element, 12b ... 1st plate-like body, 12c ... 2nd plate-like body, 13, 21 ... LD carrier, 21a ... LD mounting surface, 21b, 24 ... electrode pad installation surface, 13c ... step, 14 ... LD, 14a ... anode terminal, 15 ... lens, 16, 16a-16f ... lead terminal, 17 ... circuit board 17a, 17b ... ceramic substrate, 17c ... insulating block, 17d, 17e ... via hole, 18 ... PD for monitoring, 18a ... cathode terminal, 19 ... PD carrier, 20 ... wiring wire, 22a-22f ... wiring conductor, 23, 23a -23f, 24a-24d ... electrode pads, 25a-25d, 26a-26c ... wiring wires, 27 ... thermistors, 27a ... connection terminals, 28 ~28f ... wiring conductor.

Claims (2)

A carrier member on which a light emitting element is mounted and provided with an electrode pad of the light emitting element; a light receiving element for monitoring the light output of the light emitting element; and a circuit board on which a wiring conductor and an electrode pad are provided. An optical transmission module in which the electrode pad of the carrier member and the electrode pad of the circuit board are connected by a wire,
The carrier member has a step between a mounting surface of the light emitting element and an installation surface of the electrode pad, and the installation surface of the electrode pad and the electrode pad surface of the circuit board are located on the same plane. The optical transmission module is characterized in that the light receiving element is disposed so as to receive light emitted backward from the light emitting element.   The optical transmission module according to claim 1, wherein the step of the carrier member is formed by an inclined surface.

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