JP2009152339A - Optical device and manufacturing method thereof - Google Patents

Abstract

An optical device that can be easily managed in a joining process of mounted components and has high heat dissipation from an LD.
An optical device is obtained by attaching a thermo module 2 on which an LD 1 is mounted to a thermo module mounting surface of a stem 3 and attaching a cap to which a lens is fixed to the stem 3. Moreover, thermo-module 2, one of the thermoelectric elements 2a are soldered via the electrode 2b ₂ provided on the heat dissipating substrate 2b, the other thermoelectric elements 2a are soldered through the electrode provided on the heat absorbing block 2c LD1 is mounted on a side surface perpendicular to the thermomodule mounting surface of the stem 3 of the heat absorbing block 2c.
[Selection] Figure 2

Description

  The present invention relates to a CAN package type optical device incorporating a thermo module and a method for manufacturing the same.

  In an optical module, it is necessary to accurately control the temperature of a semiconductor laser (the emission wavelength varies depending on the temperature) in order to ensure the reliability of optical wavelength multiplexing communication and to transmit an optical signal having a stable wavelength. is there. Therefore, in the optical module, a thermo module (hereinafter referred to as TEC (Thermo electrical cooler)) is used. In the TEC, a plurality of thermoelectric conversion elements are sandwiched from above and below by an insulating substrate on which electrodes are formed, and a current is passed through the electrodes to absorb heat from one substrate and exhaust heat to the other substrate.

  A method of controlling the temperature by placing an optical module mounted with a semiconductor laser (LD: Laser Diode) that generates heat during operation in contact with the substrate serving as the heat absorption surface of the TEC is generally performed. Patent Document 1 discloses an optical module that includes a butterfly type package and has an LD and a TEC in the package. This optical module has a structure in which a chip carrier holding a LD, a lens, a monitoring photodiode and the like are mounted on a holder, and the holder is brought into contact with a substrate serving as a heat absorption surface of the TEC.

  As an optical module package, there is a coaxial type package other than the butterfly type, which can be configured smaller than the butterfly type. In an optical module of a coaxial package type in which cylindrical members are connected, a CAN package type (consisting of a stem and a cap with a lens) is often used as an optical device for storing an LD or the like. One of the reasons for using the CAN package is that it is advantageous in terms of cost because it is widely used.

  FIG. 4 is a partial cross-sectional view of a conventional CAN package type optical device (see, for example, Patent Document 2) that incorporates an LD and a TEC used in a coaxial optical module. As illustrated, the conventional optical device 10 includes an LD 11, a TEC 12, a stem 13, and a cap 14.

The stem 13 is made of metal and constitutes a CAN package having an element mounting space in cooperation with the cap 14. The LD 11 and the TEC 12 are mounted on the stem 13. The lead pins 13a for electrical connection to the glass are sealed with glass. Cap 14 has a cap shell 14a having an opening 14a ₁ at the top center, a lens 14b for condensing the transmitted light from the LD11, are glass sealed to the opening 14a _1.
When the optical device 10 is assembled, first, the TEC 12 is mounted on the stem 13, then the LD 11 is mounted on the TEC 12, and finally the cap 14 is mounted on the stem 13 by laser welding to seal the LD 11 and the TEC 12. The stopped optical device is completed.

  FIG. 5 is a diagram showing a state of a conventional optical device before the cap is attached. As shown in FIGS. 5A and 5B, the TEC 12 for temperature management of the LD 11 becomes a thermoelectric conversion element (TEC element) 12a made of a semiconductor material, a lower substrate 12b serving as a heat radiating plate, and a heat absorbing plate. The top substrate 12c is fixed. The lower substrate 12b of the TEC 12 is fixed to the stem 13, and the LD 11 is fixed on the upper substrate 12c via a carrier 11b made of aluminum nitride (AlN) and a chip carrier 11a.

  With such a configuration, when a current is passed through an electrode (not shown) formed on the lower substrate 12b, the heat generated in the LD 11 is absorbed by the upper substrate 12c via the carrier 11b and the chip carrier 11a. It can be discharged to the outside through the stem 13 from the lower substrate 12b. The TEC element 12a and the lower substrate 12b, and the TEC element 12a and the upper substrate 12c are joined with Au / 20Sn (280 ° C. melting point), respectively.

  When such an optical device is used for a coaxial optical module, the coaxial optical module includes, for example, a sleeve to which an optical connector of an optical fiber cable is attached, and a sleeve and the optical device 10 as other components. It has a joint sleeve (J sleeve) to be connected. In the coaxial optical module, alignment is performed by positioning the optical device 10 and the sleeve with respect to the J sleeve.

  However, even if this alignment is performed, in the optical device 10, if the LD 11 and the lens 14b are not positioned and fixed in advance with a predetermined accuracy, that is, the distance between the LD 11 and the lens 14b must be within a predetermined range. Thus, high photocoupling efficiency cannot be obtained. Note that the distance between the LD 11 and the lens 14b depends on the component accuracy. The LD 11 and the lens 14b are fixed to the stem 13 via the TEC 12 and the cap shell 14a, respectively, but the position of the lens cannot be adjusted with respect to the stem 13. Therefore, in order to suppress the variation in the distance between the LD and the lens due to the component accuracy so that the distance falls within a predetermined range, the LD 11 and the TEC 12 are conventionally attached to the stem 13 as shown in FIG. It was.

  When the LD 11 and the TEC 12 are attached, first, as shown in FIG. 6A, the assembled TEC 12 is bonded onto the stem 13 with Au / 20Sn solder (280 ° C. melting point). Next, as shown in FIG. 6B, the carrier 11b is joined to the top substrate 12c of the TEC 12 by Sn / 10Au solder (217 ° C. melting point). Then, as shown in FIG. 6C, the chip carrier 11a to which the LD 11 is fixed is aligned on the side surface (upper surface in the figure) of the carrier 11b so that the position of the LD 11 with respect to the stem 13 is a predetermined position. Thereafter, bonding is performed with Sn / Zn solder (melting point at 199 ° C.).

In this way, LD 11 (chip carrier 11a to which LD 11 is fixed) is finally aligned and mounted, so that LD emission from the mounting surface 13b of the stem 13 is important for the coaxial optical module (optical device 10). It is possible to suppress the variation in the position of the points (can absorb the variation in the component height of the TEC 12).
Japanese Patent Laid-Open No. 5-226797 JP 2006-324524 A

However, in this method, the melting point difference between Sn / 10Au solder and Sn / Zn solder is only 18 ° C., TEC becomes a heat insulating material, and heat at the time of soldering does not escape through the stem. A failure mode in which the bonding using Sn / 10Au solder breaks occurred at a certain rate (that is, the mounting temperature margin was small). In order to prevent this mounting failure, complicated and strict management in the joining process is necessary.
Further, in the optical device, if there are many joint surfaces on the heat transfer path from the LD to the heat absorption surface of the TEC, it is disadvantageous in terms of heat dissipation, but there is room for improvement in the conventional optical device.

  The present invention has been made in view of the above circumstances, and provides an optical device that can be easily managed in a joining process of mounted components and has high heat dissipation from an LD, and the manufacture of the optical device. It aims to provide a method.

  The optical device of the present invention is such that a thermo module on which an optical element is mounted is attached to a thermo module mounting surface of a stem, and a cap on which a lens is fixed is attached to the stem. One is soldered via an electrode provided on the heat dissipation substrate, the other thermoelectric element is soldered via an electrode provided on the heat absorbing block, and the optical element is perpendicular to the thermo module mounting surface of the stem of the heat absorbing block. It is mounted on various sides.

  In addition, it is preferable to form the contact surface with respect to the jig | tool at the time of mounting an optical element in the said heat absorption block, since the other side of the mounting surface of the optical element of a heat absorption block protrudes from the edge part of a thermal radiation board.

  The method for manufacturing an optical device according to the present invention is such that a thermo module having an optical element mounted thereon is attached to a thermo module mounting surface of a stem, and a cap having a lens fixed thereto is attached to the stem. One of the two is joined via an electrode provided on the heat dissipation board, the other of the thermoelectric elements is joined via an electrode provided on the heat absorption block, and the thermo module is assembled, and then the stem and the thermo module mounted on the heat absorption block The optical device is aligned with the mounting surface of the optical device formed on the surface perpendicular to the surface, in contact with the jig and the surface opposite to the mounting surface of the heat absorption block in contact with the jig. And a thermo module having an optical element mounted on the heat absorption block is bonded to the thermo module mounting surface of the stem.

  In addition, when joining an optical element to the mounting surface of the optical element of a heat absorption block, it is preferable to align an optical element on the basis of the lower surface of a thermal radiation board | substrate.

  According to the optical device of the present invention, since the thermo module having the heat absorption block in which the electrode portion and the optical element mounting portion are integrally formed is used, the number of components is small, so that the number of solder joint portions of the components can be reduced. it can. As a result, the number of types of solder used for bonding may be small, and the melting point difference between one solder and another solder can be increased, making management (temperature management, etc.) in the bonding process of mounted components easier. As a result, productivity is improved. Further, according to the optical device of the present invention, since the number of solder joint surfaces can be reduced, the heat dissipation of heat from the LD can be enhanced.

Hereinafter, the optical device of the present invention will be described with reference to the drawings. However, the stem and cap of the optical device are the same in structure as the stem and cap of FIG.
FIG. 1 is a perspective view showing a coaxial package type optical module in which the optical device of the present invention is used. The coaxial optical module includes a CAN package type optical device 15, a sleeve 16 for forming an optical connection between the LD 1 (see FIG. 2 described later) and an external optical transmission line, and the optical device 15 and the sleeve 16. A joint sleeve (J sleeve) 17 is provided. The coaxial optical module is formed by coupling a sleeve 16 to an optical device 15 via a J sleeve 17 and is optically connected to an external transmission line via the optical connector by inserting the optical connector into the sleeve 16. An optical signal can be transmitted.

When the coaxial optical module is aligned in this way, the transmission light output from the LD 1 is collected by the lens 4 b and enters the optical fiber of the fiber stub of the sleeve 16. Optical connection with the optical transmission line can be achieved.
However, even if alignment is performed as described above, high optical coupling efficiency cannot be obtained in the optical device 15 unless the distance between the LD 1 and the lens 4b is within a predetermined range. In the optical device of the present invention, components are configured and each component is attached so that variation in the distance between the LD and the lens due to component accuracy is suppressed and the distance is within a predetermined range.

2A and 2B are diagrams for explaining the optical device of the present invention. FIG. 2A is a perspective view of the optical device with the cap omitted, and FIG. 2B is a perspective view of the TEC of the optical device. FIG. 2 (C) is a side view of the TEC.
As shown in FIG. 2A, the optical device 15 has the LD 1 as an optical element, and uses the LD 1 whose emission wavelength varies depending on the temperature in wavelength division multiplexing, so the temperature of the LD 1 needs to be stabilized. Therefore, it has TEC2 for temperature adjustment of LD1, and a temperature measuring element (not shown). The optical device 15 also has a stem 3 and a cap 4 (see FIG. 1). In the optical device 15, the lens 4 b included in the cap 4 is positioned in a direction perpendicular to the LD mounting surface (upper surface 3 b) of the stem 3. The TEC 2 is attached on the stem 3 by, for example, Sn / 10Au solder (melting point 217 ° C.). One of the features of the present invention is the structure of TEC2.

As shown in FIG. 2B, the TEC 2 includes a thermoelectric conversion element (TEC element) 2a, a heat dissipation substrate 2b referred to in the present invention which is a substrate on the Hot surface side, and a heat absorption block (FIG. 2) which is a substrate on the Cold surface side. 5) (corresponding to the upper surface substrate + carrier) 2c. The TEC element 2a is made of a semiconductor material. As the semiconductor material, for example, a material mainly composed of a bismuth-tellurium alloy can be used. The heat dissipation substrate 2b and the heat absorption block 2c are made of a material having high insulation and high thermal conductivity, for example, aluminum nitride (AlN). A metal electrode (for example, Cu electrode) 2b ₂ is formed on the upper surface 2b ₁ of the heat dissipation substrate 2b, and a similar metal electrode is also formed on the lower surface 2c ₁ of the heat absorption block 2c, although it is not visible in the drawing. Has been.

The TEC 2 has a metal electrode 2b _{2 on} the upper surface 2b ₁ of the heat dissipation substrate 2b and the upper surface of the TEC element 2a, and a metal electrode on the lower surface 2c ₁ of the heat absorption block 2c and the lower surface of the TEC element 2a, respectively, for example, having a melting point of 270 degrees or more. It is assembled by soldering with solder (Au / 20Sn). Although not shown, the upper end portion of the lead pin 3a is for such an electrical connection to TEC2, adapted to protrude from the upper surface of the stem 3, the upper surface 2b ₁ of the lead pins 3a and the radiating substrate 2b The metal electrode 2b ₂ is electrically connected by wiring or the like. The TEC element 2a can deprive the heat absorption block 2c of heat according to the amount of current supplied via the lead pins 3a, and can give heat to the heat dissipation board 2b.

Further, the heat absorbing block 2c, the plane of the central axis side of the optical device 15 in (hereinafter, the central axis of the side surface) 2c _2, by metal deposition (metallized), the metal pattern 2c ₃ is formed. The LD 1 is mounted on the metal pattern 2c ₃ of the heat absorption block 2c via the chip carrier 1a. For mounting, for example, Sn / 10Au solder (217 ° C. melting point) is used. The LD 1 is mounted in alignment with a predetermined position of the chip carrier 1a. The center axis side surface 2c2 of the heat absorption block 2c is a plane parallel to the optical axis (perpendicular to the upper surface 3b of the stem 3) when the TEC ₂ is mounted on the stem 3, and the optical axis Since it has a width in the direction, the LD 1 can be mounted after being aligned in the optical axis direction.

Thus, the optical device 15, TEC element 2a to the metal electrode to electrically connect the electrodes formed on forming portion (the electrode unit), and the mounting surface of the center axis side 2c ₂ metal pattern 2c ₃ is formed LD1 The optical element mounting part and the heat absorption block 2c formed integrally are used. Therefore, the optical device 15 has a smaller number of parts than the conventional optical device.

Further, as shown in FIG. 2C, the endothermic block 2c protrudes from the end of the heat dissipation substrate 2b on the side opposite to the central axis side of the optical device 15 (hereinafter referred to as the outside). The outer end surface 2c ₄ is also a plane parallel to the optical axis when the TEC 2 is mounted on the stem 3, and has a width in the optical axis direction. With such a structure, when implementing outer end surface 2c ₄ of the protruding portion of the LD1 in the lower side TEC2 endothermic block 2c, with LD mounting support jigs described below, a stable TEC2 Can be supported.

Next, an example of an LD mounting auxiliary jig used for assembling the optical device of the present invention and an assembly procedure will be described with reference to FIG.
In a CAN package type optical device using a cap with a lens, the distance from the upper surface (mounting surface) 3b of the stem 3 to the lens 4b (see FIG. 1) is fixed, and the LD 1 and the lens 4b are arranged in a predetermined positional relationship. For this purpose, it is desirable to assemble the upper surface 3b of the stem 3 using the reference surface. In the present invention, the TEC 2 is attached to the stem 3 after the LD 1 is mounted as will be described later. Therefore, the LD 1 is mounted on the TEC 2 so that the lower surface 2b ₃ of the heat dissipation substrate 2b of the TEC 2 in contact with the upper surface 3b of the stem ₃ (FIG. 2C Manage the distance from (see)). For this purpose, for example, an LD mounting auxiliary jig 100 as shown in FIG.

The LD mounting auxiliary jig 100 includes a TEC sandwiching portion 20 including a heat absorbing portion side contact member 21 and a heat dissipation substrate side contact member 22, and a heat absorption portion support portion 30 having high heat dissipation. The LD mounting support jig 100, the outer end surface 2c ₄ endothermic block 2c of TEC2 is set to be on the lower side, TEC2 is placed on the heat absorbing unit support portion 30. As a result, the endothermic block 2 c is in thermal contact with the endothermic part support 30. In this state, since the TEC 2 has a structure in which the heat absorption block 2c overhangs the heat dissipation substrate 2b, the heat absorption portion support portion 30 supports the heat absorption block 2c of the TEC2.

  In the LD mounting auxiliary jig 100, the heat absorption part side contact member 21 is brought into contact with the TEC 2 placed on the heat absorption part support part 30 from the heat absorption block 2c side, and the heat radiation board side contact member 22 is arranged from the heat radiation board 2b side. By bringing them into contact, the TEC 2 is clamped by the TEC clamping unit 20. With this configuration, the LD mounting auxiliary jig 100 can stably hold the TEC2.

Moreover, the heat dissipation board side contact member 22 of the TEC clamping part 20 has the abutting member 22a integrally. The abutment member 22a, abutment surface 22a ₁ of the chip carrier 1a has been formed, the abutting surface 22a ₁ has a plane distance is determined uniquely from the lower surface 2b ₃ of the radiating board 2b of TEC2 is there. Therefore, when abutted against the chip carrier 1a on abutment surface 22a ₁ when holding the TEC2 in LD mounting support jig 100 will always predetermined value the distance to the LD1 from the lower end surface of the radiating board 2b of TEC2 It is like that.

When an optical device is assembled using such an LD mounting auxiliary jig 100, the assembled TEC 2 is first held by the LD mounting auxiliary jig 100 as described above. Then, abutting the chip carrier 1a on abutment surface 22a ₁ of the abutment member 22a, the central axis side 2c ₂ endotherm block 2c of TEC2, the chip carrier 1a (LD populated), Sn / 10aU solder (217 ° C. Melting point). Thereafter, the TEC 2 to which the chip carrier 1a is bonded is removed from the LD mounting auxiliary jig 100, and as shown in FIG. 3B, the heat dissipation substrate 2b of the TEC 2 is attached to the upper surface 3b of the stem 3 with Sn / 10Au solder (217 ° C. Melting point). Then, the optical device is completed by attaching the cap 4 (see FIG. 1) to the stem 3 by laser welding.

  In the CAN package type optical device, since the distance from the stem surface to the lens is fixed, the variation in the position of the LD emission point from the upper surface of the stem needs to be suppressed to about ± 20 μm or less in optical design. However, since the distance from the bottom surface of the heat dissipation substrate of the TEC to the LD light emitting point is always a predetermined value by mounting as described above, the above-mentioned position variation is considered even if the mounting accuracy to the stem of the TEC is taken into consideration. Can be reliably set to about ± 20 μm or less.

  As described above, according to the optical device of the present invention, it is possible to suppress the variation in the position of the LD emission point from the upper surface of the stem with a small number of parts and a small number of assembly steps.

  Moreover, when performing an assembly process in order, generally, it uses a joining material with a low melting | fusing point in order so that it may not influence with respect to the joining performed at the previous process. At this time, if the difference between the melting points of the bonding materials is large, there is no effect, but in reality, the materials that can be selected are limited, and there is no room for the temperature difference between the melting points. It was cumbersome and strict management was required, or mounting defects occurred. However, according to the optical device of the present invention, since there is a melting point difference of 60 degrees or more between the Au / 20Sn solder and the Sn / 10Au solder, strict temperature control is not necessary when mounting the chip carrier on the TEC. There is no defect. The same applies to the attachment of the TEC mounted on the chip carrier to the stem because the TEC element becomes a heat insulating material. That is, according to the optical device of the present invention, a mounting temperature margin can be ensured.

  Optical devices having LDs in a CAN package are used in optical transceiver modules such as SFF and SFP, and there is a strong demand for improvement in productivity and reduction in production costs due to the spread of industry standardization and high-speed optical transmission. It was. However, according to the optical device of the present invention, strict temperature control is not required when mounting each component, and since there are few necessary components, productivity can be improved and production cost can be reduced.

Also, since the solder that can be used for each temperature range is limited, conventional optical devices use Sn / Zn solder that is easily oxidized, or low melting point solder that is not often used in optical component mounting. It was. However, in the optical device of the present invention, since the solder used for mounting is limited to the solder widely used for optical component mounting, highly reliable mounting is possible. In other words, the optical device of the present invention has high reliability.
In addition, since the optical device of the present invention has a small number of solder joint surfaces between the LD and the stem, heat dissipation is improved in terms of product characteristics.

  In the above assembly method, when the chip carrier, that is, the LD, is mounted on the heat absorption block, the heat absorption block of the TEC is supported by the heat absorption portion support portion of the LD mounting auxiliary jig. Therefore, heat at the time of mounting the chip carrier can be released through the heat absorbing portion support portion, and at this time, strict temperature management is not necessary, so that the production cost can be reduced.

In the above description, the mechanical application is performed when the chip carrier is mounted on the TEC. However, the positioning method is not limited to this, and there is a method for recognizing an image after marking the positioning jig. Can be used.
Further, in the same optical device as in the conventional optical device, after the thermo module is attached to the stem, the LD may be aligned and attached to the thermo module.

It is a perspective view which shows the coaxial package type optical module in which the optical device of this invention is used. It is a figure explaining the optical device of this invention. It is a figure explaining an example of LD mounting auxiliary jig used for the assembly of the optical device of the present invention, and an assembly procedure. It is a fragmentary sectional view of the conventional CAN package type optical device incorporating LD and TEC used for a coaxial type optical module. It is a figure which shows the mode of the conventional optical device before cap attachment. It is a figure explaining an example of the assembly procedure of the conventional optical device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... LD, 1a ... Chip carrier, 2 ... TEC, 2a ... TEC element, 2b ... Heat sink, 2b ₁ ... Upper surface, 2b ₂ ... Metal electrode, 2b ₃ ... Lower surface, 2c ... Heat absorption block, 2c ₁ ... Lower surface, 2c ₂ ... central axis side, 2c 3 _... metal pattern, 2c 4 _... outer end surface, 3 ... stem, 3a ... lead pins, 3b ... mounting surface (upper surface), 4 ... cap, 4b ... lens, 15 ... optical device, 16 ... sleeve , 17 ... J sleeve, 20 ... TEC sandwiching section, 21 ... heat absorbing portion side contact member, 22 ... heat-radiating substrate side contact member, 22a ... abutment member, 22a 1 _... abutment surface, 30 ... heat absorbing unit support portion, 100: LD mounting auxiliary jig.

Claims (4)

A thermo module on which an optical element is mounted is attached to a thermo module mounting surface of a stem, and a cap on which a lens is fixed is attached to the stem with the lens and the optical element facing each other.
In the thermo module, one of the thermoelectric elements is soldered via an electrode provided on a heat dissipation substrate, and the other thermoelectric element is soldered via an electrode provided on a heat absorbing block,
The optical device is mounted on a side surface perpendicular to the thermo module mounting surface of the stem of the heat absorption block.   A side opposite to the mounting surface of the optical element of the heat absorption block protrudes from an end portion of the heat dissipation substrate, and forms a contact surface for a jig when mounting the optical element on the heat absorption block. The optical device according to claim 1. A thermo module mounting an optical element is attached to a thermo module mounting surface of a stem, and a manufacturing method of an optical device in which a cap with a lens fixed is attached to the stem,
After one of the thermoelectric elements is joined via an electrode provided on a heat dissipation board, the other of the thermoelectric elements is joined via an electrode provided on a heat absorption block, and the thermo module is assembled,
The mounting surface of the optical element formed on the surface of the heat absorption block perpendicular to the mounting surface of the stem and the thermo module is brought into contact with a jig on the surface opposite to the mounting surface of the heat absorption block to thermally In the state of contact, the optical element is aligned and joined,
A method for manufacturing an optical device, comprising: bonding the thermo module in which the optical element is mounted on the heat absorption block to the thermo module mounting surface of the stem.   The optical device according to claim 3, wherein when the optical element is bonded to a mounting surface of the optical element of the heat absorption block, the optical element is aligned with reference to a lower surface of the heat dissipation substrate. Manufacturing method.

Images