JP2011108939A - To-can type tosa module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a TO-CAN type TOSA module such that characteristics of a high-frequency signal driving an optical semiconductor light source element are improved. <P>SOLUTION: The TO-CAN type TOSA module includes a metallic stem 10, a metallic nose 10c fixed to the stem 10 and electrically connected to or integrated with the stem, a Peltier element as a cooling element mounted on the stem, a metallic carrier 105 mounted on the Peltier element, a signal line mounted with the optical semiconductor element and sending a drive signal to the optical semiconductor element, a relay line substrate electrically connected to the nose and having a ground pattern formed on the front, and a first wire making a ground connection between a ground pattern on a front of a carrier substrate and the ground pattern on the front of the relay line substrate, second wires 103c-103e being further provided which make ground connections between the carrier substrate and relay line substrate. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a TO-CAN type TOSA module.

  With the recent expansion of the use of the Internet, IP phones, video downloads, etc., the required communication capacity is rapidly increasing, and optical transmission / reception devices (electrical signals and optical signals are installed in optical fibers and optical communication equipment). Demand for photoelectric converters that convert to Optical transmission / reception devices and components constituting them are rapidly being modularized based on specifications so as to be easy to handle from the viewpoint of mounting and replacement, as expressed in terms such as pluggable. Light sources mounted on optical transmitter modules such as XFP (10 Gigabit Small Form Factor) are also being modularized, called TOSA (Transmitter Optical Sub-Assembly), which is a typical module form that is a box shape. BOX type module has been developed. (Non-patent documents 1, 2, 3, 4). XFP is one of the industry standards for a 10 Gigabit Ethernet (10 GbE) detachable module.

  The spread of optical transmission / reception modules has spread to LAN devices installed in office buildings and ordinary homes, and demand is increasing. As the demand increases, the demand for cost reduction of optical modules is also increasing. For this reason, it is considered to make common specifications for modules used in data communication and LAN. Furthermore, with the increase in the number of optical modules used per device, technical demands such as reducing the power consumption of the optical modules and suppressing heat generated from the optical modules are increasing.

  In response to these demands, recently, as a TOSA module that can be manufactured at a lower cost without degrading performance, the BOX type (box type) TOSA module has been replaced by a rapid increase in the TO-CAN (Transistor Outlined CAN) type optical module. Dissemination is expected. TO-CAN type optical modules have been actively developed to reduce the cost of optical modules that require temperature control for wavelength control and high-speed optical signal transmission applications exceeding 10 Gbps. Yes.

  As shown in FIG. 1, a conventional TO-CAN type TOSA module 100 includes a plurality of wiring terminals 2a, 2b, 2c,... An optical semiconductor light source element 110a and the like are mounted. The cap 5 integrated with the lens or the light extraction window 4 is resistance-welded to the stem 10 to seal the main part 1 including the optical device in the package. Furthermore, the flexible printed circuit board 6 is provided on the bottom surface of the stem 10, and the module and other components are electrically connected.

  The TO-CAN type TOSA module package shown in Fig. 1 is generally called a CAN type optical module package because it has a CAN-like shape, and was originally developed as a small package for electronic devices. The TO-CAN type package is diverted for optical modules. The TO-CAN type optical module package can be manufactured by pressing, and the manufacturing cost is reduced because it has common specifications. On the other hand, since it is smaller than the box-type TOSA module, there are many points to be improved in mounting technology such as electrical connection with the flexible printed circuit board 6, and development of the mounting technology is awaited.

Dongchurl Kim et.al., `` Design and Fabrication of a Transmitter Optical Subassembly in 10-Gb / s Small-Form-Factor Pluggable Transceiver '', IEEE JORNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS.VOL. 12, No. 4, JULY / AUGUST 2006, pp776-782 H. Yamamoto et.al., ‘‘ Wide Temperature Range Operation of 10.7 Gbit / s Uncooled DFB-LD TOSA with Extremely High Eye-Mask Margin ’’, 2006 Electronic Components and Technology Conference, pp1548-1553 Norio Okada et.al., ‘‘10 .7 Gbit / s Low Power Consumption and Low Jitter EML TOSA Employing Interdigital Capacitor’ ’, European Conference on Optical Communications 2006 (ECOC 2006), 2006, pp1-2 Y. M. Tan et.al., ‘‘ Fabrication of Thermoelectric Cooler for Device Integration ’’, 2005 Electronics Packaging Technology Conference, pp802-805

  As shown in FIG. 1, the conventional TO-CAN type TOSA module 50 has a Peltier cooling element 109 as a cooling element mounted on the stem 10, and an L-shaped carrier 105 is mounted on the Peltier element 109. On the side surface of the L-shaped carrier 105, a subcarrier having an optical semiconductor light source element 110a such as a laser diode (LD) or a modulator integrated laser in which an LD and an electroabsorption semiconductor optical modulator are integrated is mounted. A substrate 108 is placed. In addition, a relay line substrate 101 is erected on the stem 10 along with the subcarrier substrate 108. The relay line substrate 101 is formed with a signal line 102a for connecting the signal lead 2a and the optical semiconductor light source element 110a, and a ground pattern 102G that is grounded. The line 102b on the subcarrier substrate 108 and the signal line 102a on the relay line substrate 101 are connected by a bonding wire 104, and a high frequency signal for driving the optical semiconductor light source element 110a is transmitted to the high frequency signal line 102b on the subcarrier substrate 108. Power is supplied to the optical semiconductor light source element 110a via Wires 103a and 103b that connect the relay line substrate 101 and the subcarrier substrate 108 to the ground are provided on both sides of the bonding wires 104 that connect the signal lines 102a and 102b. The ground of the high frequency signal transmitted to the line is stabilized.

  However, in the configuration in which the ground lines (bonding wires) 103a and 103b are provided on both sides of the signal lines 102a and 102b, the ground is not sufficiently grounded, and when the frequency is about 10 GHz, the ground ground remains the same. Then, the problem that a high frequency signal cannot be sent to an optical semiconductor light source element stably became clear.

  In order to solve this problem, it is conceivable to increase the number of ground wirings on both sides of the signal lines 102a and 102b. However, there is a space for performing a large number of ground wirings in which stray capacitance is generated in the vicinity of the signal lines. There was no problem.

  Further, the grounded stem 10 is electrically insulated from the L-shaped carrier 105 by the Peltier element 109, and the Peltier element 109 behaves like a capacitor electrically. If both are electrically connected by the bonding wires 103a and 103b in the immediate vicinity of the Peltier element 109, the ground strengthening effect is great. However, when the electrically insulated stem 10 and the L-shaped carrier 105 are electrically connected with a bonding wire in order to strengthen the ground, the low-temperature L-shaped carrier 105 is connected from the high-temperature stem 10 via the bonding wire. A reverse flow of heat will occur. This is because the Peltier element 109 carries heat from the upper surface (L-shaped carrier 105 side) to the lower surface (stem 10 side), and is released by the Peltier element 109 in order to keep the temperature on the L-shaped carrier 105 constant. This means that the heat again flows into the carrier 105. Since the bonding wire is made of gold, this heat inflow problem cannot be avoided.

  An object of the present invention is to ground strengthen a subcarrier substrate 108 having a signal wiring for driving an optical semiconductor light source element 110a such as an LD and an L-shaped carrier 105 on which the subcarrier substrate 108 is mounted while avoiding the problem of heat inflow. Accordingly, an object of the present invention is to provide a TO-CAN type TOSA module in which the characteristics of the high-frequency signal for driving the optical semiconductor light source element 110a are improved.

  In order to solve the above problem, that is, to improve the transmission characteristics of the high frequency signal, while stabilizing the ground potential of the subcarrier substrate 108 and suppressing the influence of heat inflow, the Peltier The ground potential of the L-shaped carrier 105 that is in an electrically floating state by the element 109 must be strengthened stably.

  For this purpose, the invention described in claim 1 of the present invention is a metal stem in which a signal lead wire is fixed and grounded by a dielectric material for hermetic sealing, and is fixed to the stem and electrically connected to the stem. A metal nose connected to or integrated with the Peltier element as a cooling element placed on the stem, a metal carrier placed on the Peltier element, and an optical semiconductor element are mounted. A signal line for sending a drive signal to the optical semiconductor element, a subcarrier substrate having a ground pattern electrically connected to the carrier formed on the front surface, a signal line on the subcarrier substrate and the signal lead A signal line connected to a line, a relay line substrate formed on the front surface with a ground pattern electrically connected to the nose, a ground pattern on the front surface of the carrier substrate, and the relay A TO-CAN type TOSA module comprising a first wire for grounding a grounding pattern on the front surface of the road board, further comprising a second wire for grounding the carrier board and the relay line board This is a TO-CAN type TOSA module.

  The invention described in claim 2 is the TO-CAN type TOSA module according to claim 1, wherein the second wire is provided so as to connect the back surface of the carrier and the back surface of the nose. It is characterized by.

  The invention described in claim 3 is the TO-CAN type TOSA module according to claim 1 or 2, wherein the second wire is connected to the ground pattern of the top surface of the carrier and the top surface of the nose. It is characterized by being provided.

  According to the TO-CAN-type TOSA module of the present invention, a carrier having a signal wiring for driving an optical semiconductor light source element such as an LD is grounded while avoiding a problem of heat inflow, so that a high-frequency signal for driving the LD can be obtained. Good characteristics can be achieved.

It is a figure which shows the conventional TO-CAN type TOSA module. It is a figure which shows an example of the TO-CAN type TOSA module of this invention. It is a figure for demonstrating the position which provides a bonding wire. It is a figure for demonstrating the position which provides a bonding wire. It is a figure which shows the frequency characteristic of the loss which generate | occur | produces in the conventional TO-CAN type TOSA module. It is a figure which shows the frequency characteristic of the loss which generate | occur | produces in the TO-CAN type TOSA module of this invention.

  Hereinafter, embodiments of the present invention will be described in detail. FIG. 2 is a diagram showing an example of the TO-CAN type TOSA module of the present invention. The TO-CAN type TOSA module 100 includes a hermetic sealing dielectric 11 (see FIG. 1), 13a, 13b (see FIG. 2), and a plurality of wiring terminals (signal leads) for passing high-frequency electrical signals and DC currents. The optical semiconductor light source element 110a and the like are mounted on a stem 10 provided with (line) 2a, 2b. In the illustrated example, a high-frequency electrical signal is passed through the wiring terminal 2a. A flexible printed circuit board (FPC) 6 is provided on the bottom surface of the stem 10. However, if a sufficient hermetic seal can be ensured with 13b, it is also possible to select a material not intended for hermetic sealing for the dielectric 13a.

  The material used for the stem 10 is required to be a material having high thermal conductivity from the viewpoint of increasing the efficiency of radiating heat generated from the optical semiconductor light source element 110a which is a heat generation source. However, if a material having a high metal-based thermal conductivity is used as the material constituting the stem 10, the coefficient of thermal expansion is generally high. On the other hand, the thermal expansion is as high as that of the stem 10 so that no distortion occurs between the stem and the glass material for hermetic sealing provided around the wiring terminal 2a for passing high-frequency electrical signals due to temperature changes. It is required to use a glass material having a coefficient. Here, when a glass material having a high thermal expansion coefficient is used in preference to the thermal conductivity of the stem 10, it is necessary to pay attention to the fact that the relative dielectric constant of the glass material is generally large. The portion of the wiring terminal 2a that passes through the stem 10 can be regarded as a coaxial cable having a central conductor surrounded by a sealing circular glass. However, the coaxial cable is required to have a characteristic impedance of 50Ω as a standard value. It is done. In order to realize an impedance of 50Ω with a glass having a high relative dielectric constant, the diameter of the glass greatly exceeds 1 mm. Placing the element on the glass embedded in the stem is not reliable and a structure in which the glass occupies a large area in the stem is unacceptable.

  From these viewpoints, the stem 10 has a two-layer structure, and the upper layer 10a of the stem (the optical semiconductor light source element 110a as a heat source is mounted indirectly via the Peltier element 109) has a high thermal conductivity. The lower layer 10b of the stem is made of a material that matches a glass material having a small relative dielectric constant and thermal expansion coefficient. For example, the stem upper layer 10a is made of SPC (soft steel, cold rolled steel) having a high thermal conductivity, and the stem lower layer 10b is made of an Fe (iron) -Ni (nickel) -Co (cobalt) alloy (Kovar) having a low thermal expansion coefficient. , Kovar).

  The stem upper layer 10a is hollow around the wiring terminal 2a (air has a relative dielectric constant of approximately 1). On the other hand, the stem lower layer 10b hermetically seals the stem 10 by coaxially arranging a glass material having a small relative dielectric constant and thermal expansion coefficient as the dielectric 13b around the wiring terminal 2a. In FIG. 2, the arrangement relationship of the dielectrics 13 a and 13 b around the wiring terminal 2 a provided penetrating through the stem 10 is shown using broken lines. The dielectric constant of air used as the dielectric 13a of the stem upper layer 10a is lower than the dielectric constant of the glass material used as the dielectric 13b of the stem lower layer 10b. Therefore, the diameter of the dielectric 13a portion of the stem upper layer 10a, that is, the hollow portion can be made smaller than the diameter of the dielectric 13b portion of the stem lower layer 10b, that is, the portion provided with the glass material. In the stem upper layer 10a, if the periphery of the wiring terminal 2a through which high-frequency electrical signals pass is hollow, that is, if air having a low dielectric constant is used as a dielectric, the characteristic impedance can be reduced to 50Ω even if the sectional area around the wiring terminal 2a is reduced. It is also preferable in that it can be matched, that is, impedance matching can be taken, which can contribute to downsizing. In addition to the fact that the cross-sectional area around the wiring terminal 2a can be made small, the lens cap is resistance welded to the stem in which the area of the element mounted on the stem 10 can be secured widely and the wiring terminal periphery is hermetically sealed. The stress load at the time can be reduced, and the risk of cracks in the glass material can be reduced. In this embodiment, an example is shown in which the characteristic impedance of the high-frequency wiring terminal is 50Ω. However, the characteristic impedance may be designed to be a value other than 50Ω depending on the configuration of the chip or the external drive circuit. Good.

A nose 10c protruding upward is integrally formed on the stem 10 when the stem 10a is pressed. The nose 10c can be made of the same metal material such as SPC as the stem upper layer 10a. The stem 10 is kept at the ground potential by being grounded by a ground pin (not shown) provided on the bottom surface. The nose 10c is also kept at the ground potential by being integrally formed with the stem 10. A relay line substrate 101 is fixed to the front surface (front surface in the figure) of the nose 10c with solder. The relay line substrate 101 can be made of a ceramic material such as AlN (aluminum nitride) or Al ₂ O ₃ (alumina). On the front surface of the relay line substrate 101 fixed to the front surface of the nose 10c, a relay line (signal line) 102a connected to the signal lead wire 2a for the high frequency modulation signal (drive signal of the optical semiconductor light source element), and this relay line A dielectric (a portion where the dielectric is exposed) 80 disposed on both sides of 102a and a ground pattern 102G formed on both sides of the relay line 102a with the dielectric 80 interposed therebetween are provided. The ground pattern 102G provided on the front surface of the relay line substrate 101 is connected to the ground via a through hole h1, h2, h3... And a nose 10c disposed on the back side of the relay line substrate 101. Further, the ground pattern 102G of the relay line substrate 101 is connected to the stem 10 by solders S1 and S2 in the region close to the stem 10 so as to have the same potential as the stem 10 so that stable microwave propagation is possible. It has been strengthened.

A relay line 102 a on the relay line substrate 101 is connected to a relay line (signal line) 102 b on the subcarrier substrate 108 via a bonding wire 104. The subcarrier substrate 108 can be made of a ceramic material such as AlN (aluminum nitride) or Al ₂ O ₃ (alumina). Dielectrics (portions where the dielectric is exposed) 81 are arranged on both sides of the relay line 102b, and a ground pattern 120G is formed around the dielectric 81. In order to stabilize the microwave propagating through the relay line 102b on the subcarrier substrate 108, the ground pattern 102G of the relay line substrate 101 and the ground pattern 120G of the subcarrier substrate 108 are bonded to bonding wires 103a and 103b (hereinafter referred to as first wires). 1).

  As will be described later, the TO-CAN type TOSA module 100 of the present invention is connected to bonding wires 103a and 103b (first wires) for connecting the ground pattern 102G of the relay line substrate 101 and the ground pattern 120G of the subcarrier substrate 108. In addition, there is a feature in that bonding wires 103c, 103d, 103e, 103f and the like (hereinafter also referred to as second wires) for connecting the nose 10c and the carrier 105 are provided. By providing the second wire, the ground of the carrier 105 made of a metal such as Cu—W (copper-tungsten metal compound), that is, a conductor is strengthened and the ground of the subcarrier substrate 108 is also indirectly strengthened. be able to. As the second wire, a ribbon-shaped wire may be used in addition to the linear wire as illustrated. Each of the first wire and the second wire can be made of a good conductor material such as Au (gold). In the example of FIG. 2, the case where the second wire is provided on both the nose 10c and the back surface and the top surface of the carrier 105 is described as an example, but the present invention is not limited to this. As will be described later with reference to FIGS. 3 and 4, it may be provided on either the back surface or the top surface.

  A Peltier element 109 as a cooling element is mounted on the stem 10, and a carrier 105 for mounting various components is mounted on the Peltier element 109. For this reason, in the conventional TO-CAN type TOSA module 50 (see FIG. 1), the carrier 105 is insulated from the grounded stem 10 by being mounted on the Peltier element 109 and is in an electrically floating state. . However, in the TO-CAN type TOSA module 100 of the present invention, since the second wire connected to the nose 10c formed integrally with the grounded stem 10 is provided, the carrier 105 is ground strengthened. Yes.

  The carrier 105 has a lens 106 mounted on the upper side for collimated light from the optical semiconductor light source element 110a, and a subcarrier substrate 108 mounted on the lower side thereof. On the subcarrier substrate 108, a chip 110a in which a laser diode and an optical modulator unit are monolithically integrated is mounted as an optical semiconductor light source element. In addition, a relay line 102b and a termination resistor 110b for driving and controlling the optical modulator unit are mounted. A capacitor 110c, a thermistor 110d as a temperature sensor, and the like are mounted. When light from the laser diode passes through the optical modulator unit, a modulation signal corresponding to the electrical signal applied from the relay line 102b to the modulator unit is added (superposed) to the optical signal. The resistance value, capacitance, and arrangement of the termination resistor 110b, the capacitor 110c, and the like are designed so as to efficiently draw a high-frequency electric signal from the relay line 102b to the optical modulator unit. The carrier 105 further includes a photodiode (PD) 110e for monitoring the laser output, a capacitor 110f, and the like. The operation state of the optical device is monitored from the outside, and influences such as fluctuations in the power supply circuit are exerted on the optical device. It is designed not to be able to. Although the case where the configuration of the optical semiconductor light source element 110a is the external modulation type has been described here, the configuration may be a direct modulation type that modulates the laser diode itself.

  In addition, the upper space on the surface side of the stem 10 on which the optical semiconductor light source element 110a and the like are mounted is sealed with a cap 5 on which the lens 4 is provided. The optical output collimated by the lens 106 is designed to be collected by the lens 4 in order to couple the output of the optical device to an optical fiber or an optical waveguide provided in a receptacle portion into which the optical fiber is inserted.

  The second wire provided in the TO-CAN type TOSA module 100 of the present invention will be further described with reference to FIGS. FIG. 3 shows a TO-CAN type TOSA module in which the second wires 103c, 103d, 103e are provided on the back surface of the nose 10c and the carrier 105, and FIG. 4 shows the second wires 103f, 103g in the nose 10c and the carrier. The TO-CAN type TOSA module provided on the top surface of 105 is shown.

  In addition to the first wire, the TO-CAN type TOSA module 100 of the present invention has second wires 103c, 103d, 103e (FIG. 3), 103f, 103g (FIG. 4) for connecting the nose 10c and the carrier 105. There is a feature in having provided. By providing the second wires 103c, 103d, 103e, 103f, and 103g, first, the ground of the carrier 105 can be strengthened. This is because it is connected to the same potential as the nose 10c formed integrally with the grounded stem. Reinforcing the ground of the carrier 105 itself is important for stabilizing the microwave propagating to the relay line 102b formed on the subcarrier substrate 108. In the conventional TO-CAN type TOSA module, the carrier 105 is mounted on the Peltier element 109 and is electrically insulated from the stem 10 grounded. Therefore, there is a problem that the Peltier element 109 behaves as a capacitor, the carrier 105 is in an electrically floating state, and the high frequency signal is not stable.

In addition, by providing the second wire, second, the ground of the subcarrier substrate 108 can be strengthened. Since the subcarrier substrate 108 is formed with the high-frequency signal relay line 102b, it is naturally important to strengthen the ground of the subcarrier substrate 108 itself. Carrier 105 is formed of a conductor such as Cu-W, AlN sub carrier substrate 108 is a metal film from a surface relay line 102b is formed on the surface layer over the back surface it has been subjected (aluminum nitride), Al ₂ O ₃ It is made of a ceramic material such as (alumina). Since the subcarrier substrate 108 is fixed to the carrier 105 by soldering, if the second wire is provided to strengthen the ground of the carrier 105, the ground of the subcarrier substrate 108 is strengthened. When the ground of the subcarrier substrate 108 is strengthened, the microwave propagating through the relay line 102b is further stabilized.

  Further, since the second wire is not directly connected to the stem 10 from which heat is radiated from the Peltier element 109, the heat released from the Peltier element 109 flows into the carrier 105 and the subcarrier substrate 108 again. Be disturbed.

  Therefore, in the present invention, by providing the second wire, the ground of the carrier 105 is strengthened first, and the ground of the subcarrier substrate 108 is strengthened second, while avoiding the problem of heat inflow. The microwave propagating through the relay line 102b on the subcarrier substrate is further stabilized.

  Further, the bonding wires may be provided by providing bonding wires 103c, 103d, and 103e (see FIG. 3) so as to connect the back surface of the nose 10c and the back surface of the carrier 105, and the top surface of the nose 10c and the carrier 105 may be provided. Bonding wires 103f and 103g may be provided so as to be connected to the top surface (see FIG. 4), or both may be provided. Note that the number of second wires provided is not limited to three on the back and two on the top as shown in FIGS.

  In the above description, an example in which the ground potential of the relay line substrate on the nose is stabilized by adopting a structure of the nose integrally molded with the stem has been described as an example, but the stem and the nose are separately manufactured, and the stem and the nose are soldered or the like. A laminated structure is also possible.

  The relay line substrate structure is a grounded coplanar structure in which ground surfaces are provided on both sides of the signal line and on the lower surface of the substrate, but other structures such as a microstrip structure may be used.

  Incidentally, even if the carrier 105 is directly connected to the stem 10 with a bonding wire, the ground is strengthened. However, since the heat radiated by the Peltier element 109 flows into the subcarrier substrate again, it is not realistic. In addition, the method of increasing the number of bonding wires 103a and 103b that connect the ground pattern 102G of the relay line substrate 101 and the ground pattern 120G of the subcarrier substrate 108 also causes stray capacitance in the vicinity of the high-frequency line, which is a reality. Not right.

  FIG. 5 is a diagram showing frequency characteristics of S parameters in a conventional TO-CAN type TOSA module. The S parameter depends on how much electrical energy reaches the port 2 from the port 1 when a high-frequency electric signal is fed between any two points (referred to as ports) on the transmission line. It is an index for evaluating the characteristics of transmission lines.

  The solid line is called insertion loss (Insertion Loss), or S21, and represents the rate at which energy reaches from port 1 to port 2 in dB (decibel). S21 of 0 dB means that 100% energy is transmitted from port 1 to port 2. On the other hand, the dotted line is called “Return Loss” or “S11”, and represents the ratio of energy reflected to the power supply source in dB. S11 of 0 dB indicates that the energy supplied from port 1 is not transmitted to port 2 at all. In FIG. 5, port 1 is a flexible substrate terminal P1 (see FIGS. 3 and 4), and port 2 is a termination resistor 110b (P2 and FIG. 2).

When looking at the transmission line characteristics with the S parameter, S21 is close to 0 dB, there is no shape on the dip, and S11 is required not to exceed -10 dB as much as possible.
In the conventional TO-CAN type TOSA module 50, as shown in FIG. 5, S21 has a large dip at 5.8 GHz, 13 GHz, and 20 GHz. That is, at these frequencies, the transmission of electrical energy is significantly degraded. In general, since the waveform of an electric signal has many frequency components, if there is a frequency dependency such as dip, the electric waveform is remarkably deteriorated. Corresponding to the dip of S21, S11 greatly exceeds -10 dB in the vicinity of 5.8 GHz and 20 GHz, which means that electric reflection is large. Electrical reflection interferes with the signal waveform traveling from port 1 to port 2 and degrades the electrical waveform. These significant losses and reflections occur in the transmission lines 102a and 102b formed through the wires 104 from the relay line substrate 101 to the subcarrier substrate 108 on the carrier 105, with respect to the signal lines 102a and 102b through which the electric signal propagates. This is because the ground is not strengthened enough. The high-frequency electric signal propagates its energy without causing loss or reflection until the ground potential as a reference is stably defined.

  FIG. 6 is a diagram showing frequency characteristics of loss generated in the TO-CAN type TOSA module of the present invention. 6A shows a case where bonding wires 103c, 103d, 103e are provided on the back of the nose 10c and the carrier 105 as shown in FIG. 3, and FIG. 6B shows a case where bonding wires 103f, 103g are shown as shown in FIG. The case where it provided in the top | upper surface of the nose 10c and the carrier 105 is each shown. 5 and 6, the solid line indicates the characteristic of the S21 parameter, and the dotted line indicates the characteristic of the S11 parameter.

  Also, as shown in FIGS. 6A and 6B, when the bonding wires are provided on the back surface and the top surface of the nose 10c and the carrier 105, the frequency characteristic of S21 is dramatically improved and smoothed. The depth of the dip is also significantly shallower. Moreover, S11 is kept at -10 dB or less up to about 17-18 GHz, and it can be seen that a line structure with less electrical reflection is realized.

  When the wire is provided on the top surface, the bonding wire is provided at a position sufficiently away from the Peltier element 109 mounting portion of the stem 10, so that the amount of heat inflow can be further suppressed. Therefore, it is preferable to provide a bonding wire on the top surface of the nose 10c and the carrier 105 from the viewpoint of further suppressing the heat inflow amount.

  As described above, according to the TO-CAN type TOSA module of the present invention, the carrier having the signal wiring for driving the optical semiconductor light source element such as the LD is grounded while avoiding the problem of heat inflow. The characteristics of the high-frequency signal for driving the semiconductor light source element can be improved.

1 Main components 2a, 2b, 2c, 2d, 2e, 2f including optical devices Wiring terminals (lead pins)
4 Lens 5 Cap 6 Flexible printed circuit board (FPC)
10 stem 10a upper layer 10b stem lower layer 10c nose 11, 13a, 13b dielectric 50 for hermetic sealing (conventional) TO-CAN type TOSA module 80, 81 dielectric 100 (invention) TO-CAN type TOSA module 101 Relay line substrate 102a, 102b Relay line 102G, 120G Ground pattern 103a, 103b, 103c, 103d, 103e, 103f, 103g Bonding wire 104 Bonding wire 105 Carrier 106 Lens 108 Subcarrier substrate 109 Peltier element 110a Optical semiconductor light source element (LD)
110b Terminating resistor 110c Capacitor 110d Thermistor 110e Photodiode (PD)
110f Capacitors S1, S2 Solder h1, h2, h3... Through hole

Claims (3)

A metal stem with the signal lead fixed and grounded by a dielectric for hermetic sealing;
A metal nose fixed to the stem and electrically connected or integrated with the stem;
A Peltier element as a cooling element placed on the stem;
A metal carrier mounted on the Peltier element;
An optical semiconductor element is mounted, a signal line for sending a drive signal to the optical semiconductor element, a subcarrier substrate having a ground pattern electrically connected to the carrier formed on the front surface,
A signal line connected to the signal line on the subcarrier substrate and the signal lead wire, and a relay line substrate formed on the front surface with a ground pattern electrically connected to the nose;
A TO-CAN type TOSA module comprising: a first wire for grounding the ground pattern on the front surface of the carrier substrate and the ground pattern on the front surface of the relay line substrate;
A TO-CAN type TOSA module, further comprising a second wire for grounding the carrier substrate and the relay line substrate.   2. The TO-CAN type TOSA module according to claim 1, wherein the second wire is provided so as to connect a back surface of the carrier and a ground pattern on the back surface of the relay line substrate. 3.   3. The TO-CAN type TOSA according to claim 1, wherein the second wire is provided so as to connect a top surface of the carrier and a ground pattern on the top surface of the relay line substrate. module.

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