JP6548849B1 - Optical module - Google Patents

Abstract

The circuit board (2) is formed by forming a surface mount type package (1) for accommodating the semiconductor laser (5) therein, and a projecting structure in which a lower part of the package (1) is convex downward. Provided on the lowermost surface (1a) in contact with the metal pattern (2a) and the lower surface (1b) other than the lowermost surface (1a) in the package (1), it is possible to input and output signals to the semiconductor laser (5). Electrode pads (8) to be provided.

Description

  The present invention relates to an optical module provided with a package containing optical components.

  In recent years, in the field of optical communication technology, with the increase of communication traffic, the demand for high speed and large capacity optical communication networks is increasing. In addition, the central office and the data center possess an optical transmission device for constructing an optical communication network, and the optical transmission device is equipped with an optical transceiver for converting an optical signal and an electric signal to each other. There is.

  In order to increase the speed and capacity of the optical communication network, it is conceivable to increase the number of optical transceivers mounted in the optical transmission apparatus. However, the size and power consumption of the optical transceiver are limited by the mounting space for mounting the optical transceiver and the air conditioning capacity of the optical transmission apparatus, and in the current optical transmission apparatus, the number of optical transceivers is simply simplified. It can not be increased. For this reason, downsizing and low power consumption of the optical transceiver are urgently needed.

  In order to realize miniaturization and low power consumption of the optical transceiver, it is necessary to miniaturize and reduce the power consumption of the optical module mounted inside the optical transceiver. The optical module includes at least one element of a light emitting element, a modulation element, and a light receiving element, and the element is housed in one package together with an optical component and a temperature controller. It has become. Further, as a package applied to the optical module, a butterfly type package is representative.

  When an optical module provided with a butterfly type package is mounted inside an optical transceiver, the optical transceiver supplies electricity from the outside of the package to the inside in addition to the mounting space for mounting the butterfly type package Space is required to connect the lead pins to the circuit board. As a result, when a butterfly type package is adopted, miniaturization of the optical module is hindered.

  In order to solve such a problem, various optical modules provided with surface mount type packages are provided. When the optical module having the surface mount type package is mounted inside the optical transceiver, the space for connecting the circuit board to the lead pins for supplying electricity from the outside of the package to the inside becomes unnecessary. Therefore, the optical module can be miniaturized by adopting the surface mount type package.

  Therefore, conventionally, a semiconductor module provided with a surface mount package has been provided. Such a conventional semiconductor module is disclosed, for example, in Patent Document 1.

JP 2002-353388 A

  The conventional semiconductor module is configured such that an assembly obtained by assembling electronic components, a heat conducting member, and the like is mounted on a surface mount type package, and the package is brought into contact with the substrate surface. As a result, the above-described conventional semiconductor module improves the mounting density and achieves miniaturization, and also discharges the heat generated in the electronic component to be the heat generating member through the heat conducting member and the package, thereby reducing the mounting component size. It is intended to reduce power consumption.

  However, the conventional semiconductor module aims at exhausting heat from the surface mount type package on which the electronic component is mounted, and aims at exhausting heat from the surface mount type package on which the optical component is mounted. It is not a thing.

  Explaining this point in detail, in the conventional semiconductor module, the heat conducting member is disposed between the electronic component mounted on the surface mount type package and the housing of the semiconductor module. As a result, the pressure due to the expansion of the heat conducting member acts on the electronic component and the surface mount package, and the electronic component and the surface mount package may be displaced.

  On the other hand, the positioning accuracy of the optical component in the optical module affects the light input / output in the optical module and is a very important element in terms of performance. As a result, when the above-described conventional semiconductor module configuration is applied to the configuration of the optical module including the surface-mounted package on which the optical component is mounted, the optical component and the surface-mounted package may be misaligned. These misalignments may reduce light input / output in the optical module.

  The present invention has been made to solve the above-described problems, and to provide an optical module capable of suppressing power consumption by efficiently performing exhaust heat while achieving downsizing. To aim.

An optical module according to the present invention comprises a surface mount type package for housing a heat generating element inside, a lowermost surface formed by forming a convex structure in which a lower portion of the package is directed downward, and a package Provided on the lower surface other than the lowermost surface, between the lowermost surface and the thermal conductor, in contact with the lowermost surface and the thermal conductor, between the lowermost surface and the thermal conductor, which are capable of inputting and outputting signals to the heating element; And a non-conductive interposer.

  According to the present invention, power consumption can be suppressed by efficiently performing exhaust heat while achieving downsizing.

It is the perspective view which showed the structure of the optical module concerning Embodiment 1 of this invention. FIG. 5 is a perspective view showing a configuration of an optical module as a comparative example to the optical module according to the first embodiment. It is the figure which showed the relationship between the environmental temperature which uses a semiconductor laser, and the power consumption of TEC. FIG. 3A is a relationship diagram corresponding to the optical module according to the first embodiment. FIG. 3B is a relationship diagram corresponding to the optical module according to the comparative example. It is the perspective view which showed the structure of the optical module concerning Embodiment 2 of this invention. It is the perspective view which showed the structure of the optical module concerning Embodiment 3 of this invention. It is the figure which showed the structure of the optical module concerning Embodiment 4 of this invention. FIG. 6A is a perspective view showing the configuration of the optical module. FIG. 6B is a side view of the optical module.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Embodiment 1
FIG. 1 is a perspective view showing the configuration of the optical module according to the first embodiment.

  As shown in FIG. 1, the optical module according to the first embodiment includes a surface mount type package 1, a TEC (Thermo-electric Cooler) 3, a submount substrate 4, a semiconductor laser 5, an interposer 6, a contact pin 7, an electrode The pad 8 and the wire 9 are provided. The optical module is in contact with the surface of the circuit board 2. The circuit substrate 2, the TEC 3 and the submount substrate 4 constitute a heat conductor that conducts the heat generated by the semiconductor laser 5 serving as a heat generating element.

  The X axis, the Y axis, and the Z axis shown in FIG. 1 constitute a coordinate system of orthogonal three axes. The X axis is an axis that indicates the width direction of the optical module. The Y axis is an axis that indicates the vertical direction of the optical module. The Z axis is an axis indicating the longitudinal direction of the optical module.

  The package 1 accommodates the TEC 3, the submount substrate 4, and the semiconductor laser 5 and is in contact with the surface of the circuit substrate 2. The material of the package 1 is, for example, ceramic and glass.

  In addition, the package 1 has a box-like shape whose upper surface is open as a whole, and the lower part of the package 1 has a convex structure which is convex downward. That is, the package 1 has a convex lower surface and a concave bottom surface. Specifically, the package 1 has a lowermost surface 1a, a lower surface 1b, an outermost surface 1c, and a bottom surface 1d.

  The lowermost surface 1 a is a convex surface located lowermost in the lower surface of the package 1. Further, the lower surface 1b is disposed above the lowermost surface 1a and the lowermost surface 1c on both sides of the lowermost surface 1a.

  Corresponding to this, the bottom surface 1c is a concave surface located at the lowermost position in the bottom surface of the package 1, and is opposed to the bottom surface 1a in the vertical direction. The bottom surface 1d is disposed above the bottom surface 1c on both sides of the bottom surface 1c, and is opposed to the bottom surface 1b in the vertical direction.

  The circuit board 2 has a metal pattern 2a and a plurality of electrode pads 2b. The metal pattern 2 a is disposed on the surface of the circuit board 2. The electrode pads 2b constitute a substrate side electrode pad, and are disposed on both sides of the metal pattern 2a. That is, the lowermost surface 1a of the package 1 is in contact with the metal pattern 2a.

  The TEC 3 cools the heat generated by the semiconductor laser 5 which is a heat generating element. The TEC 3 is in contact with the bottom surface 1 c of the package 1. Further, the submount substrate 4 is in contact with the top surface of the TEC 3. The material of the submount substrate 4 is, for example, ceramic, glass or the like. Further, the semiconductor laser 5 is in contact with the upper surface of the submount substrate 4.

  The interposer 6 is for making the installation interval of the contact pins 7 described later correspond to the setting interval of the electrode pads 2 b on the circuit board 2. The interposer 6 is disposed between the lower surface 1 b of the package 1 and the electrode pad 2 b of the circuit board 2 in the vertical direction. Such an interposer 6 is formed of a non-conductive material.

  The contact pins 7 pass through the interposer 6 in the vertical direction at an interval corresponding to the installation interval of the electrode pads 2 b and are supported by the interposer 6. The contact pin 7 is a spring member formed in a spring shape, and is formed of a conductive material. The material of the contact pin 7 is, for example, a metal such as beryllium copper.

  The electrode pad 8 is provided on the package 1 and disposed so as to penetrate the lower surface 1 b and the bottom surface 1 d in the vertical direction. At this time, since the side wall including the lower surface 1b and the bottom surface 1d in the package 1 is formed of a laminated ceramic, the installation of the electrode pad 8 is easily performed. The wire 9 is made of, for example, gold, and electrically connects the semiconductor laser 5 and the electrode pad 8 by wire bonding.

  The contact pins 7 supported in a penetrating manner by the interposer 6 are sandwiched in a compressed state between the electrode pads 2 b of the circuit board 2 and the end surface of the electrode pad 8 on the lower surface 1 b side. Furthermore, the natural length of the contact pin 7 is longer than the distance between the electrode pad 2 b of the circuit board 2 and the end face of the electrode pad 8 on the lower surface 1 b side. Thereby, the contact pin 7 presses the end surface of the electrode pad 2b of the circuit board 2 and the end surface of the electrode pad 8 on the lower surface 1b side by a spring force, and electrically connects them.

  Therefore, the electric signal inputted from the electrode pad 2 b of the circuit board 2 passes through the contact pin 7, the electrode pad 8 and the wire 9 in order and is transmitted to the semiconductor laser 5.

  Further, the heat generated by the semiconductor laser 5 is transmitted through the submount substrate 4, the TEC 3, the bottom surface 1 c and the bottom surface 1 a in order, and finally reaches the metal pattern 2 a of the circuit substrate 2 to obtain light. It is discharged to the outside of the module.

  Next, the optical module according to the first embodiment and the optical module according to the comparative example will be compared using FIGS. 2 and 3. FIG. 2 is a perspective view showing the configuration of an optical module according to a comparative example. FIG. 3A is a relationship diagram corresponding to the optical module according to Embodiment 1, and FIG. 3B is a relationship diagram corresponding to the optical module according to the comparative example.

  As shown in FIG. 2, in the module according to the comparative example, the package 1A, the interposer 6A, and the electrode pad 8A are replaced with the package 1, the interposer 6, and the electrode pad 8 of the optical module according to the first embodiment. Have.

  The lower portion of the package 1A does not have the above convex structure. That is, the package 1A has the bottom surface 1c, the bottom surface 1d, and the bottom surface 1e, but does not have the bottom surface 1a. The lower surface 1e of the package 1A is a surface opposite to the bottom surface 1c and the bottom surface 1d in the top-bottom direction, unlike the bottom surface 1b of the package 1 facing the bottom surface 1d only in the top-bottom direction.

  The interposer 6A is disposed between the lower surface 1e of the package 1A and the surface of the circuit board 2, and the contact pins 7 supported through the interposer 6A are compressed between the lower surface 1e and the metal pattern 2a. In between. That is, the lower surface 1 e of the package 1 A is not in direct contact with the metal pattern 2 a of the circuit board 2. The electrode pad 8A is disposed to penetrate the bottom surface 1d and the lower surface 1e in the vertical direction.

  Therefore, the heat generated by the semiconductor laser 5 is transmitted to the submount substrate 4, TEC 3, the bottom surface 1 c, the lower surface 1 e and the contact pins 7 in order, and finally reaches the metal pattern 2 a of the circuit substrate 2. And it was discharged to the outside of the optical module.

  As a result, as shown in FIG. 3A, in the optical module according to the first embodiment, the power consumption of the TEC 3 is within 2 W even if the environmental temperature at which the semiconductor laser 5 is used reaches 75.degree. On the other hand, as shown in FIG. 3B, in the optical module according to the comparative example, when the semiconductor laser 5 is driven at 25 ° C., the TEC 3 causes a thermal runaway and does not function.

  That is, in the optical module according to the comparative example, since the lower portion of the package 1A is not convex, the interposer 6A must be disposed between the lower surface 1e of the package 1A and the metal pattern 2a of the circuit board 2. The lower surface 1e of the package 1A can not be in direct contact with the metal pattern 2a of the circuit board 2. As a result, in the optical module according to the comparative example, the exhaust heat performance is reduced compared to the optical module according to the first embodiment. Therefore, the power consumption of TEC3 accommodated in package 1A concerning a comparative example increases.

  In other words, in the optical module according to the first embodiment, the lower surface 1a of the package 1 can be brought into direct contact with the metal pattern 2a of the circuit board 2 by forming the lower portion of the package 1 in a convex structure. Can be improved. Thus, the power consumption of the TEC 3 housed in the package 1 is reduced.

  In comparison with FIGS. 3A and 3B, the material of the packages 1 and 1A is aluminum nitride, and the thermal conductivity thereof is 170 W / (m · k). The material of the contact pin 7 is beryllium copper, and the thermal conductivity thereof is 90 W / (m · k). Furthermore, the thickness between the lowermost surface 1a and the bottom surface 1c of the package 1 and the thickness between the lower surface 1e and the bottom surface 1c of the package 1A are the same. The size and cooling performance of the TEC 3 and the driving conditions of the semiconductor laser 5 are the same in the packages 1 and 1A.

  As described above, the optical module according to the first embodiment can improve the mounting density by using the surface mount type package 1. Further, in the optical module according to the first embodiment, the lower portion of the package 1 has a convex structure, and the lowermost surface 1a is brought into direct contact with the metal pattern 2a of the circuit board 2 to discharge the heat generated by the semiconductor laser 5. Performance can be improved. Thus, the optical module according to the first embodiment can reduce power consumption by efficiently performing exhaust heat while achieving downsizing.

  Further, in the optical module according to the first embodiment, by making the contact pin 7 springy, the electrical connection between the electrode pads 2 b and 8 can be made by the pressing force of the contact pin 7.

  Furthermore, in the optical module according to the first embodiment, since the contact pins 7 are supported by the interposer 6, the contact pins are inserted by inserting the interposer 6 between the lower surface 1b of the package 1 and the surface of the circuit board 2. An electrical connection between the electrode pads 2 b and 8 can be made.

Second Embodiment
FIG. 4 is a perspective view showing the configuration of the optical module according to the second embodiment.

  As shown in FIG. 4, the optical module according to the second embodiment includes a solder bump 10 instead of the interposer 6 and the contact pins 7 of the optical module according to the first embodiment.

  The solder bumps 10 are applied to the end face of the electrode pad 8 on the lower surface 1 b side and melted in the reflow process. Thereby, the electrode pad 2b of the circuit board 2 and the electrode pad 8 are electrically connected. At this time, the height dimension of the solder bump 10 matches the height dimension between the lower surface 1 b of the package 1 and the electrode pad 2 b of the circuit board 2.

  Therefore, the electric signal input from the electrode pad 2 b of the circuit board 2 passes through the solder bump 10, the electrode pad 8, and the wire 9 in order, and is transmitted to the semiconductor laser 5.

  Further, the heat generated by the semiconductor laser 5 is transmitted through the submount substrate 4, the TEC 3, the bottom surface 1 c and the bottom surface 1 a in order, and finally reaches the metal pattern 2 a of the circuit substrate 2 to obtain light. It is discharged to the outside of the module.

  In the optical module according to the second embodiment described above, the solder bumps 10 are applied to the electrical connection between the electrode pads 2 b and 8. However, the present invention is not limited to this electrical connection. For example, in the optical module according to the second embodiment, ultrasonic vibration is applied to the gold bumps mounted on each of the electrode pads 2 b and 8 to metal-bond the gold bumps to each other, thereby forming the electrode pad 2 b, Electrical connection between 8 may be made.

  As described above, in the optical module according to the second embodiment, the solder bumps 10 or the gold bumps can be applied to the electrical connection between the electrode pads 2 b and 8, so there is no need to use the interposer 6 and the contact pins 7. The number of parts can be reduced.

Third Embodiment
FIG. 5 is a perspective view showing the configuration of the optical module according to the third embodiment.

  As shown in FIG. 5, the optical module according to the third embodiment includes an interposer 16 in place of the interposer 6 of the optical module according to the first embodiment. The interposer 16 constitutes a heat conductor which conducts the heat generated when the heat generated by the semiconductor laser 5 serving as a heat generating element flows.

  The interposer 16 is disposed between the lowermost surface 1 a of the package 1 and the metal pattern 2 a of the circuit board 2. The lower portion of the interposer 16 has a convex structure that is convex downward. That is, the interposer 16 has an upper surface 16a, a lowermost surface 16b that is the lowermost surface on the interposer side, and a lower surface 16c that is the lower surface on the interposer side. The lowermost surface 1a of the package 1 is in contact with the upper surface 16a. The lowermost surface 16 b is in contact with the metal pattern 2 a of the circuit board 2.

  Furthermore, the interposer 16 has a plurality of thermal vias 16 d. The thermal vias 16 d reduce the thermal resistance toward the circuit board 2 and efficiently discharge the heat generated by the semiconductor laser 5 toward the circuit board 2. The thermal vias 16 d are filled with copper or the like, and the interposer 16 is provided to penetrate the upper surface 16 a and the lowermost surface 16 b. That is, the thermal vias 16 d provided in the interposer 16 are in contact with the lowermost surface 1 a of the package 1 and the metal pattern 2 a of the circuit board 2.

  Therefore, the electric signal inputted from the electrode pad 2 b of the circuit board 2 passes through the contact pin 7, the electrode pad 8 and the wire 9 in order and is transmitted to the semiconductor laser 5.

  Further, the heat generated by the semiconductor laser 5 is transmitted to the submount substrate 4, TEC 3, the bottom surface 1 c, the bottom surface 1 a and the thermal via 16 d in order, and finally reaches the metal pattern 2 a of the circuit substrate 2. Therefore, it is discharged to the outside of the optical module.

  As described above, in the optical module according to the third embodiment, even when the interposer 16 is disposed between the lowermost surface 1a of the package 1 and the metal pattern 2a of the circuit board 2, the lower portion of the interposer 16 has a convex structure. The thermal via 16 d is provided inside the interposer 16. Thereby, the optical module according to the third embodiment can suppress power consumption by efficiently performing exhaust heat while achieving downsizing.

Fourth Embodiment
6A and 6B are diagrams showing the configuration of the optical module according to the fourth embodiment.

  As shown in FIGS. 6A and 6B, the optical module according to the fourth embodiment includes a window 11, a lens 12, and an optical fiber 13 in addition to the optical module according to the first embodiment. The lens 12 and the optical fiber 13 are optical components.

  The window 11 is opened on the side wall of the package 1 so as to face the laser emission port of the semiconductor laser 5. The lens 12 transmits the laser beam emitted from the semiconductor laser 5 toward the window 11 by transmitting the laser beam. The optical fiber 13 combines the laser light output by the lens 12 and transmits the combined light to the outside of the optical module.

  Here, the lens 12 and the optical fiber 13 as optical components have to be installed in a state of being positioned with high accuracy in order to suppress the decrease in light input / output in the optical module. However, the relative positional relationship between the semiconductor laser 5, the lens 12, and the optical fiber 13 may change due to the stress acting on the package 1. In particular, since the lower part of the package 1 has a convex structure, distortion is easily generated in the X-axis direction which is the step direction.

  Therefore, the semiconductor laser 5, the lens 12, and the optical fiber 13 are arranged such that their axial centers coincide with the Z-axis direction orthogonal to the X-axis direction in which distortion easily occurs. That is, the semiconductor laser 5, the lens 12, and the optical fiber 13 have an optical axis along a direction orthogonal to the convex cross section of the package 1.

  As described above, in the optical module according to the fourth embodiment, even if the lower portion of the package 1 has a convex structure, the optical loss caused by the distortion generated by the convex structure can be reduced.

  However, the positional relationship between the package 1, the circuit board 2, the TEC 3, the submount substrate 4, the semiconductor laser 5, the interposers 6 and 16, the contact pins 7, the electrode pads 8, the wires 9 and the solder bumps 10 is as described above. It is not limited to those positional relationships in the embodiment 1-4.

  The materials of the package 1, the submount substrate 4, the contact pins 7, the wires 9, the gold bumps and the like are not limited to the respective materials in the embodiment 1-4 described above. For example, when the material of the submount substrate 4 is metal, the submount substrate 4 can efficiently dissipate the heat generated by the semiconductor laser 5.

  The shapes and configurations of the package 1, the circuit board 2, the TEC 3, the submount substrate 4, the semiconductor laser 5, the interposers 6 and 16, the contact pins 7, the electrode pads 8 and the solder bumps 10 are the same as those in the embodiment 1-4 described above. It is not limited to each shape and each configuration.

  For example, the package 1 has a configuration in which a thermal via filled with copper is provided in a bottom plate portion formed by the lowermost surface 1a and the bottommost surface 1c, or a bottom plate portion formed by the lowermost surface 1a and the bottommost surface 1c. Alternatively, a metal plate having a thermal conductivity better than that of other portions may be provided. Thereby, the package 1 can efficiently dissipate the heat generated by the semiconductor laser 5 from the lowermost surface 1a.

  The optical module according to Embodiment 1-4 can obtain the same effect even if the semiconductor laser 5 to be a light emitting element is replaced with various elements such as a light receiving element. As described above, when the light receiving element is applied, the optical signal input through the optical fiber 13 traces the transmission path of the electric signal in the reverse direction described above.

  Furthermore, although the lens 12 is installed inside the package 1, it may be attached outside the window 11. The number and type of lenses 12 can be set as appropriate. The lens 12 may be a collimator lens or a condenser lens.

  And although the optical module concerning Embodiment 1-4 is used as an electrical signal input application to the package inside from the package exterior, you may use it as an electrical signal output application to the package exterior from the package inside.

  In the present invention, within the scope of the invention, free combination of each embodiment, or modification of any component in each embodiment or omission of any component in each embodiment is possible. It is possible.

  In the optical module according to the present invention, the lower part of the surface mount type package for housing the heat generating element inside is a convex structure having a convex shape toward the lower side, thereby achieving downsizing while efficiently exhausting heat. Thus, the power consumption can be suppressed, and it is suitable for an optical module in which a package containing optical components is mounted.

  Reference Signs List 1 package, 1a bottom surface, 1b bottom surface, 1c bottom surface, 1d bottom surface, 2 circuit boards, 2a metal pattern, 2b electrode pads, 3 TEC, 4 submount substrates, 5 semiconductor lasers, 6 interposers, 7 contact pins, 8 electrodes Pads, 9 wires, 10 solder bumps, 11 windows, 12 lenses, 13 optical fibers, 16 interposers, 16a top surface, 16b bottom surface, 16c bottom surface, 16d thermal vias.

Claims (9)

A surface mount package that houses the heat generating element inside;
A lowermost surface formed by forming a convex structure in a downward direction toward the lower side of the lower portion of the package;
An electrode pad provided on the lower surface other than the lowermost surface of the package and capable of inputting and outputting a signal to the heating element
An optical module comprising a nonconductive interposer disposed between the lowermost surface and a heat conductor so as to be in contact with the lowermost surface and the heat conductor . A thermal via is provided inside the interposer disposed between the lowermost surface and the heat conductor, and is provided with a thermal via for discharging heat transferred from the lowermost surface to the heat conductor. 1 light module. A substrate-side electrode pad provided on a circuit substrate constituting the heat conductor;
And a spring member having conductivity and pressing the electrode pad and the substrate-side electrode pad by a spring force.
The optical module according to claim 2, wherein the spring member is supported by the interposer. The interposer is
The lower side of the interposer is formed by forming a convex structure having a convex shape facing downward, and the interposer-side lowermost surface in contact with the heat conductor;
And an interposer-side lower surface other than the interposer-side lower surface in the interposer;
The thermal via is provided to penetrate between the upper surface of the interposer and the lower surface on the interposer side.
The optical module according to claim 3, wherein the spring member is supported through an upper surface of the interposer and a lower surface on the interposer side. The interposer is
Wherein while being disposed between the lowermost surface with the heat conductor, any one of claims of claims 1 to 4, wherein the arrangement is the fact between the lower surface and the circuitry board Light module. The optical module according to any one of claims 1 to 5, wherein the package accommodates an optical component therein. The optical component is
The optical module according to claim 6, further comprising an optical axis along a direction orthogonal to the convex cross section of the package. The optical module according to any one of claims 1 to 7, further comprising a thermal via provided so as to penetrate the lowermost surface. The optical module according to any one of claims 1 to 8, wherein the lowermost surface has a thermal conductivity higher than the thermal conductivity of the lower surface.

Images