JP2001337250A - Optical semiconductor hermetically sealed container and optical semiconductor module - Google Patents

Abstract

(57) [Object] To solve an optical axis shift due to distortion generated when an airtightly sealed container for mounting an optical semiconductor element is mounted on a fixed substrate. A portion of a projected portion of a frame, which is shorter than a length in a longitudinal direction, is provided at a connection portion of a hermetically sealed container with a fixed substrate to reduce distortion from the substrate. As a means for this, a short portion is provided in a metal bottom plate or a connection flange.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical semiconductor storage container for storing an optical semiconductor used for optical communication, and an optical semiconductor module for storing the optical semiconductor therein.

[0002]

2. Description of the Related Art An optical semiconductor module is an indispensable device for optical communication in recent years, and its characteristics greatly affect communication accuracy and communication volume. Its use is to convert information sent by optical multiplex communication into an electric circuit by an optical semiconductor module and vice versa to convert information from an electric circuit to an optical multiplex communication circuit. This conversion is performed by the optical semiconductor, but if the positional relationship between the light flux of the light and the condenser lens and the optical semiconductor is displaced, it greatly affects the accuracy of the information. Therefore, this positional relationship has been emphasized for a long time.

[0003] In particular, those that affect this positional relationship,
Although quality control is at the stage of module manufacturing, quality accuracy has been improved through many efforts. Next, a difference in thermal expansion characteristic of component materials due to a change in operating temperature may cause distortion. Regarding these, there is an invention in which the heat generated by the optical semiconductor is avoided by adopting a structure that emphasizes heat dissipation. Japanese Patent Application Laid-Open No. H11-74395 discloses an invention in which in order to cope with such a temperature change, the bottom plate of the module is doubled and avoided by combining different materials having different Young's moduli. Also, Japanese Patent Application Laid-Open No. Hei 6-31474
In Japanese Patent Application Publication No. 7 (1999), there is an invention aiming at a significant heat dissipation effect by integrating the connection flange portion and the bottom plate and making the bottom plate portion thicker than the flange thickness.

[0004] The present invention further relates to a means for avoiding mechanical distortion generated when connecting to a fixed substrate. In the optical communication module, the mounting portion to the fixed substrate is usually flat, and the mounting surface of the fixed substrate should be flat. However, modules that are actually industrial products
In the manufacturing process, it is slightly distorted due to heat history such as brazing, and the bottom surface is slightly warped. The fixed substrate may not always be flat. Due to these factors, the connection flange portion and / or the bottom plate are distorted when the module is mounted, and further the frame is distorted, which adversely affects the positional relationship between the optical semiconductor and the condenser lens housed in the container. There is.

[0005] It is necessary to devise a device that alleviates these distortions and does not shift the positional relationship. As such a countermeasure, a bottom plate portion and a connection flange portion disclosed in Japanese Patent Application Laid-Open No. 6-82659 are butt-connected with different metals, and a material having a lower longitudinal elastic coefficient than the material of the bottom plate portion is used for the flange portion. Is disclosed.

Further, Japanese Patent Application Laid-Open No. 11-74619 discloses that the part of the butted portion of the bottom plate and the flange overlaps with the bottom plate in the above-mentioned Japanese Patent Application Laid-Open No. 6-82659. Each of these is a means for avoiding the tightening distortion of the screw at the time of connection with the fixed substrate.

In Japanese Patent Application Laid-Open No. 10-50872, the connection flange is not integrated with the bottom plate, but is integrated with the frame so that the bottom plate is not affected by the distortion of the frame. The invention is also disclosed.

[0008]

As described above, many techniques have been disclosed and means for avoiding the positional deviation have been taken, but they are structurally inadequate and, in particular, are not connected to the frame. Further measures are required to stabilize the mutual position of the optical fiber and the optical window, the condensing lens installed therein, and the optical semiconductor installed on the bottom plate. For example, JP-A-6-82569 and JP-A-11-746.
In the case of Japanese Patent Publication No. 19, the connecting flange portion is a means for avoiding by absorbing the distortion of the screwing, but a relaxing force for recovering all the pulling force of the frame body is required. Further, in Japanese Patent Application Laid-Open No. 10-50872, although the connection flange pulls the frame, distortion to the bottom plate is suppressed, but the relative position of the frame itself to the bottom plate may be shifted.

[0009]

SUMMARY OF THE INVENTION According to the present invention, a connection portion between an optical semiconductor module and a fixed substrate is narrowed so that distortion generated in connection between the fixed substrate and the connection flange is not transmitted to the module body. . That is, by providing a connection portion between the fixed substrate and the bottom plate with a portion shorter in length in the longitudinal direction of the module frame, the longitudinal end of the module frame has a portion that is not fixed to the fixed substrate. As a result, distortion of the fixed substrate and distortion generated on the mounting surface of the module are not transmitted to the entire module.

With such a structure, the distortion of the frame by the connection flange is not directly affected, and the bottom plate is only affected by the distortion near the center thereof. Such a shape is achieved by the method shown in FIG. 2 in which the connection flange has a short portion, and a short portion is attached to the bottom plate so that a part of the metal bottom plate is in contact with the fixed substrate. There is the method of FIG. 1 for extending the connection flange. Further, there is a method in which the short portion is located on the metal bottom plate portion and the portion is fixed to the connection flange (FIG. 3). In any case, a portion shorter in length than the longitudinal length of the module frame can be formed. The short portion may be located at the center of the lower surface of the module or slightly shifted to one side.

Further, a structure as shown in FIG. 4 is preferable in that the thermal conductivity of the bottom plate is maintained, distortion due to connection with the fixed substrate is avoided, and easiness of processing is taken into consideration. This structure has a short part in the metal bottom plate,
The shorter portion is in contact with the fixed substrate, and both side portions of the bottom plate in contact with the fixed substrate are further reduced in width, and an extended portion of a connection flange connected in the longitudinal direction is connected to this portion. . In this structure, the connection flange is formed of one part, and the bottom plate having a short length portion is connected thereto by soldering or brazing material to achieve the configuration of the present invention, and the length of the metal bottom plate is reduced. Since the short portion is in contact with the fixed substrate, the structure can maintain thermal conductivity.

The part to which the module is fixed corresponds to the short part, and its effect is determined by the ratio to the free part. Assuming that the area of the portion corresponding to A in FIG. 5 is s and the area of the portion corresponding to A + B in FIG. 5 is S, it is preferable that s / S <0.95. FIG.
If the portion corresponding to A is too small, the effect of the metal bottom plate for dissipating heat generated by the optical semiconductor to the fixed substrate is reduced. Therefore, it is preferable that 0.5 <s / S.

When importance is placed on heat dissipation, in the method shown in FIG. 2 in which the connection flange is formed by extending the connection flange and in the case of FIG. 3, it is preferable to use a material having good heat conductivity for the connection flange. In the case of the method of FIG. 1 and the method of FIG. 4 in which a short portion is added to the metal bottom plate portion, the heat conduction characteristics required for the bottom plate are applied as they are. In any of the methods, it is preferable to select a material having a small longitudinal elastic modulus capable of reducing distortion caused by screwing, for a portion corresponding to the connection flange. Furthermore, it is also desirable to cut out the connecting flange to reduce the rigidity in order to reduce the distortion by the shape effect.

In this way, by floating the hermetically sealed container from the fixed substrate, an optical semiconductor module can be obtained in which distortion generated when screws are fixed to the fixed substrate can be reduced.

[0015]

FIG. 1 shows an example of the present invention. The module placed on the fixed substrate 1 is connected to the connection flange 3 and the metal bottom plate 2 and is screwed in a screw hole 9. The metal bottom plate 2 has a portion with a short length, and is connected to the frame 4 at a widened portion at the top. The frame 4 has an optical window 6 in the longitudinal direction, and an optical fiber 10 through a ferrule.
Connected to An optical semiconductor 7 is disposed on the heat sink inside the frame 4. External terminals 5 are connected in a direction perpendicular to the light window mounting portion of the frame, and are usually connected to both sides of the frame. A lid 8 for hermetic sealing is connected to an upper portion of the frame 4 by welding or the like. Here, the hermetically sealed container refers to the connection flange 3, the metal bottom plate 2, the frame 4, the optical window 6, the external terminal 5, and the lid 8.

In the configuration shown in FIG. 1, since the metal bottom plate 2 is in close contact with the fixed substrate 1 directly or via an insulating film or the like, the temperature rise due to the heat generated in the container is reduced via the metal bottom plate 2. In this case, heat is dissipated to the fixed substrate, so that distortion due to thermal expansion due to temperature rise can be avoided, which is preferable.

FIG. 2 shows another example of the present invention. In FIG. 2, the connection flange 3 is located between the metal bottom plate 2 and the fixed substrate 1,
It is fixed to the fixed substrate 1 at the screw holes 9 by screwing, and is connected to the metal bottom plate 2 by soldering, brazing, or the like. The upper part of the metal bottom plate 2 has the same structure as that of FIG.

FIG. 3 shows still another example of the present invention. Since a short portion is provided on the metal bottom plate 2 and connected to a flat connection flange by soldering or brazing, this is a preferable example in terms of cost. In addition, the heat conductivity of the wax is good,
In addition, when a material having a small longitudinal elastic modulus is used, the effect of buffering the strain becomes greater.

FIG. 4 shows a more preferred embodiment of the present invention. The connection flange 3 is formed integrally with a projected portion of the metal frame and a portion protruding for screwing, and a metal bottom plate is connected to the inside thereof with a reduced length. The longitudinal direction of the frame body is not directly connected to the connection flange, and in the direction orthogonal to the longitudinal direction of the frame body, that is, the side direction, a part of the bottom plate is reduced in width and connected to the connection flange 3 at that part. You. Such a structure is easy to process as in FIG. 3 because the connecting flange portion is integrated, and is more preferable than FIG. 3 because the metal bottom plate is in direct contact with the fixed substrate. It is.

FIG. 5 is an explanatory diagram relating to the size of the short portion between the module and the fixed substrate, which is a common part of the present invention. There is a constriction between the flange portion on the fixed substrate and the bottom plate portion of the module due to the short length, so that distortion on the fixed substrate can be avoided from the force that also distorts the module. When the module is fixed on the entire bottom plate (FIG. 6), the distance of receiving the distortion from the fixed substrate is long, and it acts greatly as a moment. However, when the module is fixed only at the portion A as shown in FIG. Since the effect of the distortion of only affects the length of A, B
The distortion applied to the portion is reduced. The ratio between A and B is represented by an area ratio as in s and S in FIG. actually,
Since the stress acts according to the principle of the cantilever, it depends on the length of the connection flange in the screwing direction, but since the width of the frame is almost the same, the same expression can be obtained in terms of area.

More specifically, in the module shown in FIG. 5, the distance from the center in the longitudinal direction of the module to the end of the shorter portion is l ₁ , and the distance from the center in the longitudinal direction of the module to the end of the module frame is When the distance to the part and L _1, l ₁ /
The value of L ₁ becomes less susceptible to impact on the distortion the smaller. Also, in the reverse direction, the smaller the value of l ₂ / L ₂ is, the more effective the distortion is. That is, (l ₁ + l ₂ ) / (L ₁
+ L ₂ ). Since the widths of the modules are the same, the same can be said for the value s / S obtained by multiplying these by the width T. Therefore, the effect is discussed depending on the magnitude of s / S. s / S is smaller than 1, and the smaller the value, the greater the effect and the more preferable. In the present invention, from the results of various experiments,
A preferable result was obtained when s / S <0.95. This means
It is not necessary to make the frame symmetrical, and only one side is sufficiently effective.

On the other hand, if the s / S is too small, the action of the metal bottom plate for dissipating heat generated by the mounted optical semiconductor element to the fixed substrate is reduced, and the action of fixing the frame body with the flange is impaired. It is. Preferably s / S> 0.5
Should be within the range. The optical semiconductor module is
In particular, a large amount of heat is generated in a portion where the optical semiconductor element is mounted, and therefore the entire surface of the metal bottom plate does not rise at the same temperature. In particular, by providing a short portion immediately below the optical semiconductor element mounting portion where the temperature rise is large, it is possible to exhibit the effect of distortion and to maintain the heat dissipation.

The optical semiconductor element is mounted on the container thus constructed, connected to a circuit with an external terminal by an Au wire or the like, a lens such as sapphire glass is mounted on an optical window, an optical fiber is mounted via a ferrule, and finally a lid is provided. When the module is hermetically sealed by attaching the module, the module of the present invention is completed.
When this module is mounted on a fixed substrate, it can be mounted without concern for unevenness of the fixed substrate, distortion due to work at the time of screwing, and the like. Even after attachment, the positional relationship between the optical fiber, the lens, and the optical semiconductor element is not affected by the distortion, and stable input / output is exhibited.

[0024]

EXAMPLES Example 1 An airtightly sealed container having the shape shown in FIG. 1 was prepared. For the metal bottom plate, CuW was used as a material, and the shape was formed into a near shape by a metal injection molding method, and the dimensions were finished by a correction process. The dimensions are Fe-Ni-Co alloy (trade name:
Kovar) frame (20.85 mm x 12.7 mm x
7.9 mm) and a short portion in the longitudinal direction was formed. The short portion has a shape cut by 0.52 mm from both ends in the longitudinal direction.
That is, the cross-sectional area s of the shortened portion is 12.7 ×
(20.85−0.52 × 2) = 251.6 mm ² , and the projected area S of the frame is 12.7 × 20.85 = 26.
Since 4.8 mm ² , s / S = 0.95. A connecting flange is connected to the bottom plate in the longitudinal direction of the frame using a silver solder. The connection flange portion is formed by punching a 0.5 mm plate material of an Fe-Ni-Co alloy.

Example 2 An airtightly sealed container having the shape shown in FIG. 2 was prepared. The frame used had the same material dimensions as those in Example 1, and the metal bottom plate used was flat CuW.
The connection flange is 0.5mm thick FeNi-
A plate of the Co alloy was punched out, a plate having a dimension of a short length portion was stacked at a predetermined position, and connected with a silver solder to obtain a shape shown in FIG. The length of the shorter part at this time is 19.5 mm
And In this case, s / S is 0.935.

Example 3 A hermetically sealed container having the shape shown in FIG. 3 was prepared. Also in this case, the frame body has the same material dimensions as that of the first embodiment, and the metal bottom plate is processed into a stepped plate shape having a short portion by a metal injection molding method as in the first embodiment, and is modified. Finished the dimensions. The dimension of the short portion was 18.75 mm. The short part is Fe-
It was connected to the center of a connection flange made of a Ni-Co alloy plate with a silver solder. The s / S at this time is 0.90.

Example 4 A hermetically sealed container having the shape shown in FIG. 4 was prepared. The frame had the same material dimensions as the frame used in Example 1 in the same manner as described above, and the metal bottom plate was processed to the near shape by the metal injection molding method as in Example 1. The dimension of the short part is modified to 18.35 mm, and the side part is 1.0 mm wide and cut into 0.5 mm. As shown on the back surface of FIG. 4, the connection flange 3 has screw holes 9 on the left and right sides, which are integrated in the longitudinal direction of the frame body, and the metal bottom plate 2 is located at the center. The metal bottom plate 2 and the connection flange are connected by silver solder at the 1 mm width portions on both sides. The s / S in this example is 0.88.

Comparative Example 1 A conventional hermetically sealed container shown in FIG. 6 was prepared. The frame had the same material dimensions as in Examples 1 to 4, and the metal bottom plate used was a CuW plate. On the side of the bottom plate opposite to the frame, 0.5 m of Fe-Ni-Co alloy
A connection flange formed by punching from a plate of m was connected with a silver solder. The s / S in this case is naturally 1.0.

The above five types of hermetically sealed containers were prepared, all of which were equipped with optical semiconductor elements of the same specification, sapphire glass lenses, optical fibers, etc. were attached, wired, sealed with a lid, and modularized. . When the performance of the five types of modules was checked, there was no problem with the matching of the optical fibers, lenses, and semiconductor elements.

When these five types of modules were screwed to the fixed substrate, the modules were screwed with spacers interposed therebetween so as to generate an upward warpage of 30 μm at the center of the module.
After that, when the performance was checked, the conventional product of Comparative Example 1 was
Since the optical axis was shifted by 10 μm or more, the light output was reduced by 3 dB or more. In the other Examples 1 to 4, the deviations of the optical axes were all within 3 μm, and the decrease in optical output was also within 1 dB. From this experiment, it can be understood that the embodiment according to the present invention has a structure capable of absorbing distortion due to external force such as screwing against warpage of the fixed substrate, warpage of the bottom plate of the module, and the like. The structure can be realized by combining a metal bottom plate or a connection flange having a portion shorter than the frame in the longitudinal direction of the module.

From the above results, the value of s / S is 1.
Although the distortion was large in 00, Example 1 of 0.95,
Example of 0.935, Example 3 of 0.90 and 0.8
Since Example 4 of Example 8 both absorbs strain, the effect is exhibited even if the length is short. For this size, s / S should be reduced depending on the amount of strain applied, but as can be understood from the above experiment, 30 μm
Since the degree of distortion is sufficiently large for practical use, s /
If the value of S is less than 0.95, the distortion of that level can be cleared. When the distortion is small, s /
The value of S may be large. However, s / S = 1.0
In the case of 0, since the connection portion with the fixed substrate directly pulls the wall of the frame, a portion having a slightly short length is required.

(Experimental example) As described above, a structure in which a part of a metal bottom plate or a connection flange has a short length is made to be a structure capable of absorbing distortion, but it is another specification of a metal bottom plate. A description will be given of a certain heat dissipation property. The shorter the length, the greater the effect on distortion as the length is reduced, but the area of connection of the module to the fixed substrate is reduced, and the effect of heat dissipation is reduced accordingly. Therefore, it is advantageous to minimize the amount of shortening the length.

A portion where the length of the module used in Example 1 was shortened was further cut to investigate the heat dissipation. Experimental Example 1 is Example 1, and s / S is 0.95. In Experimental Example 2, 1.56 mm was further cut from both sides to shorten the length, and s / S was set to 0.80. In Experimental Example 3, s / S was further reduced to 0.65, and similarly, in Experimental Example 4, s / S was 0.50, and in Experimental Example 5, s / S was 0.45. I cut it down. FIG. 7 shows the results of investigating the heat dissipation using the above five types of modules. From FIG. 7, it is preferable that s / S exceeds 0.5. Practically, it is important to be able to clear the distortion, so that 0.8 <s / S <0.95 achieves a particularly preferable effect.

The data collection means shown in FIG. 7 is such that when the experimental sample is fixed on an aluminum fixed substrate having a thickness of 20 mm and input to the mounted optical semiconductor element, the temperature rise of the chip thermistor mounted at the same time. Divided by the input was used. The smaller the temperature rise, the better the heat dissipation. As the length is shortened, the metal bottom plate is partially narrowed, so that the heat generated in the module concentrates at that portion, resulting in thermal resistance. That is, it can be understood that the heat dissipation is more largely due to the heat conduction through the metal bottom plate than to the air.

[0035]

As described in the embodiments and the experimental examples, the present invention provides a module having a reduced length on the bottom plate or the connection flange of the module to generate the unevenness of the fixed substrate, the bottom plate of the module or the connection flange. The structure absorbs the distortion at the time of screwing. It does not affect the optical axis positional relationship between the optical semiconductor element, the lens, and the optical fiber, and as a result, the reliability of input / output is improved.

[Brief description of the drawings]

FIG. 1 is an example of a sectional view of a hermetically sealed semiconductor container of the present invention.

FIG. 2 is another example of the present invention.

FIG. 3 is yet another example of the present invention.

FIG. 4 is a preferred example of the present invention. a) is a cross section, and b) is a back surface.

FIG. 5 is an explanatory diagram of elements of the present invention. a) is the side and b) is the top.

FIG. 6 shows a conventional technique.

FIG. 7 is a graph showing heat dissipation of the present invention.

[Explanation of symbols]

1. 1. fixed substrate, 2. metal bottom plate; Connection flange,
4. Frame, 5; External terminal, 6. Light window, 7. Optical semiconductor,
8. Lid, 9. Screw hole, 10. Optical fiber; B. the length of the shortened portion; The difference between the length of the frame and the shortened portion, l ₁ , l ₂ . Distances of the shortened portions from the center of the frame, L ₁ , L ₂ . Frame length from the center of the frame,
Projected area of the frame, s. The projected area of the shortened part,
T. Width of frame and bottom plate,

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H037 AA01 BA03 BA12 DA36 DA38 5F041 AA40 AA43 DA07 DA61 DA73 DA76 EE04 EE06 EE08 FF14 5F073 BA01 EA29 FA07 FA08 FA29

Claims (7)

[Claims] 1. A metal bottom plate, a connection flange to a substrate,
An optical semiconductor hermetic sealing container having an external terminal and a frame having an optical window and containing an optical semiconductor element therein, 1) the frame is connected to one surface of a metal bottom plate. 2) the other surface of the metal bottom plate is in contact with the fixed substrate via a connection flange or directly; 3) the metal bottom plate or the connection flange An optical semiconductor hermetically sealed container, wherein a portion of the projected portion of the frame onto the fixed substrate, the portion having a length shorter than the length in the longitudinal direction is provided. 2. The method according to claim 2, wherein the metal bottom plate has a short portion.
2. The hermetically sealed optical semiconductor container according to claim 1, wherein a portion having a short length is in contact with the fixed substrate. 3. The hermetically sealed optical semiconductor container according to claim 1, wherein the connection flange has a short portion, and the short portion is connected to a metal bottom plate. 4. A metal bottom plate having a short portion.
The hermetically sealed optical semiconductor container according to claim 1, wherein the portion is connected to a connection flange, and the connection flange is in contact with the fixed substrate. 5. A metal bottom plate having a short portion,
The shorter portion is in contact with the fixed substrate, and both side portions of the bottom plate in contact with the fixed substrate are further reduced in width, and an extended portion of a connection flange connected in the longitudinal direction is connected to this portion. An optical semiconductor hermetically sealed container according to claim 1. 6. The hermetically sealed optical semiconductor according to claim 1, wherein the size of the short portion of the metal bottom plate or the connecting portion of the connecting flange is within a range given by the following equation. Stop container. 0.5 <s / S <0.95 s: cross-sectional area of the portion whose length is reduced S: projected area of the frame on the fixed substrate 7. A lens, a ferrule, and an optical fiber are provided in an optical window, an optical semiconductor is mounted therein, and required wiring is provided by a wire or the like, using the hermetically sealed container according to claim 1. After performing the above, the optical semiconductor module is hermetically sealed with a lid.