JP2004288669A - Optical semiconductor element module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a connecting structure of leads so as not to bring about a displacement between a package and an electronic cooler by the residual stress of the lead connected to the electronic cooler, and to prevent the short circuiting of the lead upon any vibration or impact. <P>SOLUTION: This optical semiconductor element module includes an optical semiconductor element, the electronic cooler provided at the signal terminal at a lower part, a carrier solder connected to the upper surface of the electronic cooler, a connecting substrate formed separately from the carrier and connected to the upper surface of the electronic cooler, the package for housing the electronic cooler, a conductor wire connected to the connecting substrate and the package, and the leads for connecting the connecting substrate to the signal terminal of the electronic cooler. The leads 10a are connected on the pattern substrate 11 mounted on a Peltier 10 in a structure not to connect to the other component for forming an optical system. Even if the bending part of the lead 10a is released from a stress, the displacement of an LD2 and a lens 7 does not occur only by applying the stress to the pattern substrate lead 9a on the Peltier 10. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical semiconductor element module in which an electronic cooler on which an optical semiconductor element is mounted is mounted inside a package.
[0002]
[Prior art]
Optical semiconductor element modules are currently widely used in optical fiber communication systems to convert electrical signals into optical signals. 2. Description of the Related Art As an optical semiconductor element module, for example, a laser diode module (LD module) equipped with a laser diode (LD) for converting an electric signal input from the outside into an optical signal is known.
[0003]
2. Description of the Related Art Optical semiconductor element modules used for communication applications are required to stably output optical signals for a long period of time, such as 10 to 25 years. However, since the characteristics of the LD easily change depending on the temperature, various characteristics such as the wavelength of the generated optical signal and the optical output tend to change. For this reason, an electronic cooler and a thermistor for adjusting the temperature of the LD are installed in the LD module so that a stable optical signal can be obtained. 2. Description of the Related Art Conventionally, as an electronic cooler, for example, an LD module equipped with a Peltier element has been known (for example, see Patent Document 1).
[0004]
[Patent Document 1]
JP-A-4-332186 (4 pages, FIG. 1)
[0005]
This electronic cooler is configured by joining a ceramic substrate to the upper and lower surfaces of a Peltier element, and generates a temperature difference between the two substrates to control the temperature of the LD mounted on the ceramic substrate on the upper surface. A voltage is applied to the Peltier element by a pair of leads (Peltier leads) connected to the ceramic substrate on the high temperature side. Generally, the Peltier lead is connected to a side wall of a package containing an electronic cooler and is electrically connected to a wiring pattern on a feedthrough. As a result, a control voltage from outside the package is transmitted to the Peltier device.
[0006]
[Problems to be solved by the invention]
In the conventional optical semiconductor device module, after the Peltier lead is joined to the electronic cooler, the Peltier lead is bent and connected to the feedthrough, so that stress is accumulated in the bent portion of the Peltier lead. Due to the effect of the residual stress, a phenomenon occurs in which the bending angle of the Peltier lead is increased or decreased in a direction in which the bending angle is widened or narrowed due to long-term use.
[0007]
The stress from the Peltier lead causes a solder creep phenomenon, which slightly displaces the electronic cooler soldered to the bottom surface of the package. This caused an angular displacement between the optical axis of the LD mounted on the electronic cooler and the optical axis of the optical fiber bonded to the package. As a result, there has been a problem that the optical axis of the optical fiber is displaced and the optical output is reduced. This phenomenon was more remarkable when a highly rigid material was used for the Peltier lead.
[0008]
In addition, when a soft member having low rigidity is used for the Peltier lead, the Peltier lead is instantaneously deformed by vibration or impact, and there is a problem that a short circuit occurs between the Peltier lead and the package or between the Peltier leads. .
[0009]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and it is intended to prevent displacement between a package and an electronic cooler due to residual stress of a lead connected to the electronic cooler, and to reduce vibration. It is an object of the present invention to provide a lead connection structure that prevents a short circuit of a lead at the time of impact or impact.
[0010]
[Means for Solving the Problems]
An optical semiconductor element module according to the present invention is an optical semiconductor element, an electronic cooler provided with a signal terminal at a lower part, a carrier soldered to an upper surface of the electronic cooler, and the carrier is formed separately. A connection board joined to an upper surface of the electronic cooler, a package accommodating the electronic cooler, a conductor wire connected to the connection board and the package, and a signal terminal of the connection board and the electronic cooler And a lead for connecting
[0011]
Further, the optical semiconductor element, a first insulating substrate, a second insulating substrate wider than the first insulating substrate, and a plurality of the semiconductor devices disposed between the first insulating substrate and the second insulating substrate. An electronic cooler having a thermoelectric element, a carrier mounted on an upper surface of the first insulating substrate, and a carrier on which an optical semiconductor element is mounted on an upper surface of a front part, the carrier being formed separately from the carrier, A connection substrate mounted on a rear portion of an upper surface of the first insulating substrate; and a side substrate protruding from an inner side wall, wherein the second insulating substrate is joined to an inner bottom surface to house an electronic cooler. And a conductor wire connected to the upper surface of the connection substrate and the upper surface of the side substrate, and a lead connecting the upper surface of the connection substrate and the upper surface of the rear portion of the second insulating substrate. Is also good.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiment 1 FIG.
1 and 2 are diagrams showing a configuration of the optical semiconductor element module according to the first embodiment. FIG. 1 is a cross-sectional view of the optical semiconductor element module, and FIG. It is a top view.
[0013]
In the figure, a package 1 is based on a metal casing formed in a box shape, and a feed-through 1a made of a ceramic substrate is fitted on the lateral side wall of the base in a state of maintaining airtightness, and penetrates the package 1. It is formed in shape. On the upper surface of the feedthrough 1a, a wiring pattern 15 of a conductor is formed, so that the inside and outside of the package 1 are electrically connected while maintaining the airtightness. The upper surface of the package 1 has an opening, and an upper lid 1c is joined to the upper surface and hermetically sealed.
[0014]
The bottom surface of the package 1 is joined to the bottom surface of the Peltier 10 by solder 3a. The carrier 9 is joined to the upper surface of the Peltier 10 with the solder 3b. An LD carrier is soldered to a front portion of the upper surface of the carrier 9, and a laser diode (LD) 2 as an optical semiconductor element is mounted on the upper surface of the LD carrier (in FIG. Therefore, the LD carrier and LD2 are identified for the sake of clarity). The bottom surface of the PD mount 8b is soldered to the upper surface of the carrier 9. A photodiode (PD) 8 as a light receiving element is soldered to a side surface of the PD mount 8b so as to face the rear surface of the LD2. The lower surface of the lens holder 7 holding the lens is joined to the front surface of the LD carrier 9 so as to face the front surface of the LD 2. The thermistor 13 is joined to the upper surface of the PD mount 8b. A light passage hole is provided in a front side wall inside the package 1, and an optical window 14 is joined so as to close the light passage hole. A spacer 6 is joined to the outer front wall of the package 1 so as to cover the light passage hole, and a fiber holder 4 is joined to the spacer 6. The fiber 5 is bonded to the fiber holder 4.
[0015]
A pattern substrate 11 is joined to the rear part of the upper surface of the Peltier 10 by solder 3b separately from the LD carrier 9. The bonding area of the pattern substrate 11 on the upper surface of the Peltier 10 is sufficiently smaller than the bonding area with the package 1 on the lower surface of the Peltier 10. The Peltier 10 is provided with a ceramic insulating substrate 10a on the lower surface and a ceramic insulating substrate 10b on the upper surface, and the upper and lower surfaces of a plurality of Peltier elements 10c are joined between the insulating substrate 10a and the insulating substrate 10b. It is configured. The insulating substrate 10a is longer in the front-rear direction than the insulating substrate 10b, and the insulating substrates 10a and 10b are arranged such that a portion where the insulating substrate 10a and the insulating substrate 10b do not overlap is located behind the insulating substrate 10a when viewed from above. Be placed. Wiring patterns are provided on the upper surface of the insulating substrate 10a and the lower surface of the insulating substrate 10b. With this wiring pattern, all the Peltier elements are connected in series. The Peltier device is oriented such that the heat absorption side of the Peltier device is on the insulating substrate 10b side and the heat removal side is on the insulating substrate 10a side.
[0016]
A pair of signal input terminals 10d for applying a voltage to the Peltier element are provided on the upper surface of the rear part of the insulating substrate 10a. One end of a pair of leads 12a is connected to a pair of signal input terminals 10d connected to the Peltier 10, respectively. The other end of the lead 12a is joined to the upper surface of the pattern substrate 11. The lead 12a is bent into a C-shape and is joined to the insulating substrate 10a and the pattern substrate 11. One end of the wire bond (conductor wire) 12b is joined to the upper surface of the pattern substrate 11, and the other end is joined to the wiring pattern 15 on the upper surface of the feedthrough 1a. The pattern board 11 is used as a connection board which relays between the feedthrough 1a and the Peltier 10 to be electrically connected.
[0017]
The optical semiconductor element module according to the present embodiment is configured as described above, and operates as follows.
The LD 2 converts an electric signal input from the outside via the feedthrough 1a into an optical signal. When a current is applied, the LD 2 generates an optical output in two front and rear directions according to the amount of the current. The front light generated by the LD 2 is condensed using the lens held by the lens holder 7, passes through the optical window 14, and is finally condensed on one end surface of the optical fiber 5. Thus, the front light of the LD 2 is extracted as an optical signal to the outside. The PD 8 receives the back light from the LD 2 and generates a current (monitor current) proportional to the amount of received light. By outputting this monitor current to the outside of the optical semiconductor element module via the feedthrough 1a, it is possible to monitor a change in the light emission amount of the LD2.
[0018]
The Peltier 10 is used to generate a temperature difference between the upper and lower surfaces of the Peltier according to the voltage applied to the lead 12a, and to control the temperature of the LD 2. The thermistor 13 has a characteristic that its resistance value changes in accordance with the temperature, and is used to detect the temperature of the LD 2. The signal input terminal 10d of the Peltier 10 is electrically connected to the outside via the lead 12a, the pattern substrate 11, the wire bond 12b, and the conductive pattern 15 provided on the feedthrough 1a. Can be transmitted to the Peltier 10.
[0019]
In the optical semiconductor element module according to the present embodiment, residual stress is accumulated in the bent portion of the lead 12a over a long period of use, and the bending angle of the lead 12a changes due to release of the residual stress. Here, in the optical semiconductor element module according to the present embodiment, the other end of the lead 12a whose one end is joined to the lower surface of the Peltier is not directly joined to another component such as the package 1 or the carrier 9 on which an optical component is mounted. Structure is used. With this structure, the residual stress in the bent portion of the lead 12a generates an acting force on the pattern substrate 11 on the Peltier 10 with the joint between the Peltier 10 and the insulating substrate 10a as a fulcrum. Due to the action of the stress from the leads 12a, a solder creep phenomenon occurs at the solder joint portion of the pattern substrate 11, and the pattern substrate 11 is slightly displaced. However, since no optical components are mounted on the pattern substrate 11, the optical axis directions of the LD 2 and the lens holder 7 are not changed. Of course, the optical axis does not change between the optical fiber 5 bonded to the package 1 and the LD 2.
[0020]
Also, since the lead 12a is bent and joined in a C-shape, it has low rigidity and resiliency, so that residual stress accumulated in the bent portion can be further reduced, and the lead 12a and the Peltier 10, In addition, it is possible to prevent the electrical connection between the pattern substrate 11 and the wire bond 12b from being disconnected.
[0021]
In addition, since the LD 2 and the lens 7 can be configured so as not to be displaced, it is possible to obtain an optical semiconductor element module which has no optical axis shift due to a solder creep phenomenon and has a stable optical output for a long time.
[0022]
Further, the lower surface of the Peltier 10 and the feedthrough 1a are electrically connected to each other by relaying via the conductive pattern 11b on the pattern substrate 11. For this reason, the lead length of the lead can be reduced as compared with a conventional optical semiconductor element module in which the lower surface of the Peltier 10 and the feedthrough 1a are directly connected using the Peltier lead. Further, since the upper surface of the pattern substrate 11 can be disposed above the upper surface of the Peltier 10, the length of the wire bond 12b connecting the pattern substrate 11 and the feedthrough 1a can be shortened. In particular, by arranging the conductive pattern 11b on the pattern substrate 11 to face the feedthrough 1a and arranging the conductive pattern 11b close to the wiring pattern 15 on the feedthrough 1a, the length of the wire bond 12b can be minimized. can do.
As a result, it is possible to suppress the instantaneous deformation of the wire bond wiring due to vibration and shock, and to configure a configuration in which a short circuit between the wire bonds does not occur.
[0023]
Of course, by adjusting the height of the upper surface of the feedthrough 1a so that the upper surface of the pattern substrate 11 and the upper surface of the feedthrough 1a have the same height, the length of the wire bond 12 can be further reduced. Needless to say.
[0024]
On the other hand, FIGS. 3 and 4 show an example of a conventional optical semiconductor element module as a comparative example. FIG. 3 is a cross-sectional view of a conventional optical semiconductor element module, and FIG. 4 is a top view thereof.
In the figure, a Peltier 10 is joined to the bottom surface of a package 1 by solder 3a. Further, an LD carrier 9 on which the LD 2, the PD 8, the lens 7, and the thermistor 13 are mounted is further joined by solder 3b. An optical window 14 is bonded to the front surface of the package 1, and a fiber 5 is bonded to the outside of the front surface of the package 1 via a spacer 6 and a fiber holder 4. A feedthrough 1 a is provided on the side surface of the package 1 so as to penetrate the package 1. The feed-through 1a is provided with a wiring pattern, thereby making an electrical connection inside and outside the package 1. Further, the Peltier 10 is connected to the feedthrough 1a via the lead 100a. The lead 100a and the feedthrough 1a are joined by solder.
[0025]
In this example, stress is accumulated in the bent portions (dotted line portions in FIG. 3) of the pair of leads 100a that are bent at two locations due to long-term use. By releasing the residual stress, a stress is generated in a direction in which the lead bending angle increases or decreases. Due to the stress from the lead 100a, a solder creep phenomenon is expected to occur in the solder 10a. As a result, displacement of the Peltier 10, the LD 2 and the lens 7 bonded thereon occurs, and as a result, an optical axis shift occurs. In particular, since a highly rigid material is used for the Peltier lead 10a, this phenomenon appears more conspicuously.
[0026]
On the other hand, in the optical semiconductor device module according to the first embodiment, the pattern substrate 11 separate from the LD carrier is arranged on the upper surface of the Peltier 10, one end of the lead 12a is connected to the pattern substrate 11, and the other ends of the lead 12a are connected. The end is connected to the lower surface of the Peltier 10. As a result, even if the lead bending angle changes due to the effect of the residual stress of the lead 12a of the Peltier 10, the stress does not affect the optical system, there is no optical axis shift due to the solder creep phenomenon, An optical semiconductor element module with stable optical output can be obtained.
[0027]
Also, since the other end of the wire bond 12b, one end of which is connected to the conductive pattern 11b on the pattern substrate 11, is connected to the feedthrough 1a, the electrical connection between the lower surface of the Peltier 10 and the feedthrough 1a is performed. It is possible to minimize the length of the wire bond 12b. As a result, it is possible to suppress instantaneous deformation of the wire bond wiring due to vibration and impact, and to provide a configuration in which a short circuit does not occur.
[0028]
【The invention's effect】
Even if the bending angle of the lead changes due to the residual stress of the lead connected to the electronic cooler, the stress does not affect the optical system, and there is no optical axis shift due to solder creep phenomenon. An optical semiconductor element module having a stable optical output can be obtained.
[0029]
In addition, since the electrical connection is made via the connection board, the length of the wire bond can be minimized, and as a result, a short circuit of the wire bond wiring due to vibration and impact can be prevented. is there.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an optical semiconductor element module according to a first embodiment.
FIG. 2 is a top view of the optical semiconductor element module according to the first embodiment.
FIG. 3 is a cross-sectional view of an example of an optical semiconductor device module showing a conventional configuration.
FIG. 4 is a top view of an example of an optical semiconductor element module showing a conventional configuration.
[Explanation of symbols]
1 package, 1a feedthrough, 2 laser diode (LD), 3 solder, 4 fiber holder, 5 fiber, 6 spacer, 7 lens holder, 8 photodiode (PD), 9 LD carrier, 10 Peltier (electronic cooler), 12a Lead (Peltier lead), 11 pattern substrate, 11b conductive pattern, 12b wire bond, 13 thermistor, 14 optical window, 15 wiring pattern.

Claims (5)

An optical semiconductor element;
An electronic cooler provided with a signal terminal at the bottom,
A carrier soldered to the upper surface of the electronic cooler,
A connection substrate formed separately from the carrier and joined to an upper surface of the electronic cooler;
A package containing the electronic cooler;
A conductor wire connected to the connection board and the package,
An optical semiconductor device module comprising: a lead for connecting the connection board and a signal terminal of the electronic cooler. An optical semiconductor element;
An electron having a first insulating substrate, a second insulating substrate wider than the first insulating substrate, and a plurality of thermoelectric elements disposed between the first insulating substrate and the second insulating substrate. Cooler,
A carrier mounted on an upper surface of the first insulating substrate and having an optical semiconductor element mounted on an upper surface of a front portion;
A connection substrate formed separately from the carrier, and mounted on a rear portion of an upper surface of the first insulating substrate;
A package having a side substrate protruding from an inner side wall, wherein the second insulating substrate is bonded to an inner bottom surface and accommodates an electronic cooler;
A conductor wire connected to the upper surface of the connection substrate and the upper surface of the side substrate,
An optical semiconductor element module comprising: a lead for connecting an upper surface of the connection substrate and an upper surface of a rear portion of the second insulating substrate. 3. The optical semiconductor device according to claim 2, wherein the electronic cooler is soldered to a bottom surface inside the package, the connection board is soldered to an upper surface of the electronic cooler, and the carrier is soldered to an upper surface of the electronic cooler. module. The lower surface of the first insulating substrate and the upper surface of the second insulating substrate are provided with conductor patterns, and the plurality of thermoelectric elements are connected in series by the conductor patterns of the first and second insulating substrates.
3. The optical semiconductor device module according to claim 2, wherein the leads have a pair of leads, and the pair of leads form a terminal pair of the thermoelectric element connected in series. 3. The optical semiconductor element module according to claim 2, wherein the conductor pattern on the side substrate of the package and the conductor pattern on the connection substrate are arranged close to or substantially at the same height.

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