JPH11145317A - Package for optical semiconductor device and optical semiconductor module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a package and an optical semiconductor module to offer a package form which can be formed, even by omitting the dimension control around a ceramics terminal parts material, also simplifying the forming process of the package by eliminating the junction parts of the side frame materials, suppressing the generation of thermal distortion. SOLUTION: In a package, a vessel in which a photosemiconductor device is stored is formed by a side frame member 2, including a front frame part 2a provided with a means for connecting a metal board 1 and a optical fiber, and a part of the side frame member 2 is formed by a ceramics terminal member 3 having more than two layers of coating formed with metallized wiring 3c. Then, by holding the bottom face of the ceramics terminal member 3 to the side frame terminal member 2, the surface to a seal ring 5, one side of the longitudinal direction to the front frame part 2a, and by having the side frame member 2 abut so that the other side is made a free side or both sides are made free sides, each terminal member is jointed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a container for housing an optical semiconductor device. More specifically,
The present invention relates to a container and a module for housing an optical fiber amplifier or an excitation light source which is equipped with an optical element such as a CATV or the like which needs to operate at high speed and with low noise and a semiconductor IC, and which requires an electronic cooling element for temperature control.

[0002]

2. Description of the Related Art Conventionally, an optical semiconductor package for accommodating an optical semiconductor element has a metal substrate made of a copper-tungsten alloy having an area for mounting the optical semiconductor element on a central upper surface; Iron surrounding the storage area
A ceramic terminal having means for fixing an optical fiber to a front frame part by brazing a side frame member made of a nickel-cobalt alloy or an iron-nickel alloy on a metal substrate, and a metallized wiring layer to which external lead wires are connected A member is fitted to the side frame member, and a seal ring serving as a metal frame body for hermetically sealing the optical semiconductor element is brazed on the upper portion.

The optical semiconductor element is bonded and fixed to the optical semiconductor element mounting area of the metal substrate, and each electrode of the optical semiconductor element is connected to a metallized wiring layer to which an external lead wire is connected via a bonding wire. Then, the optical fiber is bonded to the optical fiber fixing ring of the front frame portion by YAG welding by irradiating a laser beam, and finally, a cover is put on the upper surface of the seal ring and sealed, thereby completing an optical semiconductor module as a unit. It is.

The main functions required of an optical semiconductor package are to efficiently dissipate the heat generated when an optical signal and an electric signal are converted into each other, and to provide an optical fiber and an optical semiconductor element due to thermal distortion of the package. The package structure is such that the optical axis does not shift. To efficiently dissipate the heat generated, a Peltier element as an electronic cooling element, which is a heat pump, is placed under the mount base of the optical semiconductor element, and a material with high thermal conductivity is used for the components of the package. This is a well-known technique.

[0005] As a package structure for preventing thermal distortion,
A structure disclosed in Japanese Patent Application Laid-Open No. 6-314747 has been proposed. This structure will be described with reference to FIG. 13. Reference numeral 101 denotes a metal substrate having a mount base 101a on which the optical semiconductor element 106 is mounted. A side frame member 102 surrounding the optical semiconductor element mounting area is brazed on a metal substrate.
A ceramic member terminal 103 having a metallized wiring layer to which an external lead wire is connected is fitted inside the dimension Y of the side frame member 102, and a seal ring 104 for hermetically sealing the optical semiconductor element 106 is joined to the upper part. .

A metallized wiring layer 108 to which an external lead wire is connected is connected via a bonding wire 107 to each electrode of the optical semiconductor element 106 bonded and fixed on the mount base 101a. Irradiation of the laser beam onto the optical fiber fixing ring 110 of the front frame 109 causes Y
The optical fiber 111 is fixed by AG welding. In order to maintain the airtightness in the package, the cover 112 is brazed to complete the optical semiconductor module.

The package configured as described above is
The thickness of the inner mount base 101a of the metal substrate 101 is X
When the thickness of the mounting portion at both ends is T, 1.0 ≧ T ≧
It is described that if 0.3 mm and X ≧ 2T, thermal distortion of the package can be suppressed.

[0008]

In the structure of the conventional package shown in FIG. 13, since the ceramic terminal member is fitted within the inner dimension Y of the side frame member, it shrinks in the longitudinal direction during firing. It is necessary to control the accuracy of the inner dimension Y of the side frame member in accordance with the characteristics of the ceramic which is easy to perform, but if the width of the ceramic terminal member is too large, expensive processing steps such as polishing and dicing cutting are required. Become. If the width of the ceramic terminal member is too small, an extra brazing material must be injected at the time of joining, which breaks the balance of heat capacity and tends to cause thermal distortion.

In view of the above, the present invention proposes a package form that can be realized even without strict dimensional control around the ceramic terminal member, and simplifies the package forming process by minimizing the joints of the side frame members, thereby reducing the heat generation. Provided are a package and an optical semiconductor module in which generation of distortion is suppressed.

[0010]

A package for housing an optical semiconductor element comprising a metal substrate on which an optical semiconductor element is mounted, a side frame member having means for supporting a ceramic terminal member and connecting an optical fiber, and a sealing cover. If at least one end face in the longitudinal direction of the ceramic terminal member is joined as a free end that is not restrained by the side frame member, a package that does not require strict size control around the ceramic terminal member is obtained.

In the package, the upper surface of the ceramic terminal member may abut on the metal seal member, or the metal seal member can be omitted if the upper and lower surfaces are configured to abut on the cutouts of the side frame member.

By providing a continuous step on the outer peripheral edge of the upper surface of the ceramic terminal member, a package that can be easily brazed is obtained.

By sandwiching a thin metal plate having a thickness of 0.2 mm or less on the joint surface between the ceramic terminal member and the side frame member,
Even if there is a difference in the coefficient of thermal expansion between the ceramic terminal member and the side frame member, a package having good airtightness after brazing is obtained.

If the side frame member is constituted by a cylindrical injection molded body of a copper-tungsten alloy by a copper infiltration method and a ceramic terminal member of aluminum nitride, a package having few joints and good heat radiation can be obtained. .

If the optical semiconductor element package described in any one of claims 1 to 6 is mounted with at least the optical semiconductor element and the optical fiber and then sealed with a sealing cover, the manufacturing process is simplified compared to the prior art and the cost is reduced. In addition, an optical semiconductor module having a small thermal distortion and a stable optical output can be provided.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings. FIG.
1 is a three-dimensional view of a first embodiment of the package for an optical semiconductor device of the present invention.

In FIG. 1, reference numeral 1 denotes a metal substrate made of a copper-tungsten alloy having an area for mounting an optical semiconductor element in the center, and mounting holes 1a are provided on both sides. Reference numeral 2 denotes a side frame member that surrounds four sides along the outer edge of the metal substrate 1, and an optical fiber is connected to the front frame portion 2a,
A fixing means of a light member such as a fixing hole or a window portion 2b which transmits light is provided. The side frame member 2 may be formed by individually joining side frames including a flat front frame portion by brazing or the like. It may be integrally formed as shown.

As the injection molding method, Japanese Patent Application Laid-Open No.
The copper infiltration method described in JP-B-76 is preferable. More specifically, a step of forming a mixed powder in which nickel powder, tungsten powder, and at least one of molybdenum powder and tungsten-molybdenum powder are mixed so that the nickel powder is 1% by weight or less;
A step of kneading with an organic binder obtained by mixing a wax component having a temperature of not more than 0 ° C. and an organic substance that hardly leaves a distribution, a step of molding the kneaded substance by injection molding, and a step of demolding the molded substance to remove pores. Through the process of forming
It is obtained by infiltrating molten copper into a porous molded body.

In FIG. 2, the injection molded body serving as the side frame member 2 is formed by cutting a rectangular quadrangular prism into a circle and milling or end milling the X, Y, and Z planes, and applying light of an optical fiber to the front frame 2a. The provision of the transparent window 2b simplifies the number of bonding steps, and improves reliability and dimensional accuracy by bonding to a ceramic terminal member such as aluminum nitride having good heat dissipation and an approximate coefficient of thermal expansion. A high side frame member 2 can be obtained.

In FIG. 1, the ceramic terminal member 3 is made of a fired body of two or more layers of aluminum oxide or aluminum nitride, and the lower layer member 3a is a strip-shaped green sheet formed of a high melting point of tungsten, molybdenum, manganese or the like. A metal paste obtained by adding and mixing an appropriate organic solvent and a solvent to the metal powder is applied as a metallized wiring layer 3c by a well-known screen printing method, and as an upper layer member 3b,
The preform is formed by stacking substantially strip-shaped green sheets. The external terminals 4 are brazed to the metallized wiring layer 3c.

FIG. 3 is a plan view of the ceramic terminal member 3 in which the lower layer member 3a and the upper layer member 3b are overlapped. In this figure, one surface A in the longitudinal direction is in contact with the front frame portion 2a side, the other surface B is a free end, and the surface C is in contact with the side frame 2 so that the ceramic terminal member 3 itself and the side frame 2 Absorb dimensional errors. 3d is a continuous step described later with reference to FIG. In FIG. 1, when the ceramic terminal member 3 is integrated in a U-shape by extending the C surface of the ceramic terminal member 3 opposed thereto, one of the terminals comes in contact with the front frame portion 2a and the other end is free. Although it is possible to use the edge, it is difficult to correct the workability of the green sheet and the shrinkage distortion after firing.

Referring again to FIG. 1, a seal ring 5 is joined to a portion where the upper surface of the ceramic terminal member 3 and the upper surface of the side frame member 2 including the front frame portion 2a are aligned. After mounting at least the optical semiconductor element and the optical fiber inside the container configured as described above, the optical semiconductor module is completed by sealing with a sealing cover.

FIG. 4 shows a three-dimensional view of the second embodiment. Mounting holes 1a are provided on both sides of a metal substrate 1 made of a copper-tungsten alloy having an area for mounting an optical semiconductor element. On the metal substrate 1, side frames 7 surrounding four sides are joined along the outer edge thereof. The front frame portion 7a which is a part of the side frame member 7 is provided with means such as a hole for fixing or connecting an optical fiber or a window portion 2b for transmitting light. The side frame member 7 may be individually joined by brazing side frames including a flat front frame portion. However, the side frame member shown in FIG. 7 may be integrally formed.

In FIG. 5, an injection molded body of a cylindrical quadratic prism serving as the side frame member 7 is cut into a circle, and the X and Y planes are milled or end-milled to transmit a light of an optical fiber to a front frame portion 7a. Providing the portion 2b simplifies the number of joining steps. As a method for producing the injection molded body, a copper infiltration method similar to that of the first embodiment is preferable.

In FIG. 4, the ceramic terminal member 8 is made of a fired body of two or more layers of aluminum oxide or aluminum nitride, and the lower layer member 8a is a strip-shaped green sheet on which a metallized wiring layer 3c is adhered. As the upper layer member 8b, substantially strip-shaped green sheets are stacked and preformed. In the metallized wiring layer 3c,
The external terminals 4 are brazed. 4, the ceramic terminal member 8 is joined to the side frame 7 at both ends as free ends, so that the dimensional accuracy of the side frame 7 and the ceramic terminal member 8 in the longitudinal direction may be rough. Further, the side frame 7 including the upper surface of the ceramic terminal member 8 and the front frame 7a.
The seal ring 5 is joined to the upper surface of the substrate. After mounting at least the optical semiconductor element and the optical fiber inside the container configured as described above, the optical semiconductor module is completed by sealing with a sealing cover.

FIG. 6 shows a three-dimensional view of the third embodiment. Mounting holes 1a are provided on both sides of a metal substrate 1 made of a copper-tungsten alloy having an area for mounting an optical semiconductor element. On the metal substrate 1, side frames 9 surrounding the four sides are joined along the outer edge thereof. The front frame portion 9a, which is a part of the side frame 9, is provided with means such as a hole for fixing or connecting an optical fiber or a window portion 2b for transmitting light. Side frame 9
Although the side frames including the flat front frame portion may be individually joined by brazing, the side frame member 9 may be cut into a cylindrical shape by injection molding, and the side frame member 9 may be formed as shown in FIG. It may be integrally molded.

In FIG. 7, the injection molded article of the cylindrical quadratic prism serving as the side frame member 9 is cut into X1, X2, Y1, Y
Milling or end milling two surfaces to form front frame 9a
If the window 2b through which the light of the optical fiber is transmitted is provided, the number of bonding steps can be simplified and the seal ring 5 as a single product can be omitted. As a method for producing the injection molded body, a copper infiltration method similar to that of the first embodiment is preferable.

In FIG. 6, the ceramic terminal member 3 is made of the same fired body of two or more layers of aluminum oxide or aluminum nitride as the one used in the first embodiment. Terminal 4 is brazed. An optical semiconductor module is completed by mounting at least an optical semiconductor element and an optical fiber inside a container in which the metal substrate 1, the side frame member 9, and the ceramic terminal member 3 are brazed, and sealing with a sealing cover.

FIG. 8 shows a three-dimensional view of the fourth embodiment. Mounting holes 1a are provided on both sides of a metal substrate 1 made of a copper-tungsten alloy having an area for mounting an optical semiconductor element. A side frame member 10 surrounding the four sides is joined to the metal substrate 1 along the outer edge thereof. An optical fiber is connected to the front frame portion 10a which is a part of the side frame member 10,
Means such as a fixing hole or a window 2b for transmitting light are provided. The side frame member 10 may be individually joined by brazing the side frames including the flat front frame portion. However, the side frame member is formed by injection-molding into a cylindrical shape, and as shown in FIG. Frame member 1
0 may be integrally molded.

In FIG. 9, a cylindrical quadratic prism injection molded body serving as the side frame member 10 is sliced into X1, X2, Y1,
Milling or end-milling the Y2 surface to make the front frame 1
If the window portion 2b for transmitting the light of the optical fiber is provided at 0a, the number of joining steps is simplified and the seal ring 5 as a single product can be omitted. As a method for producing the injection molded body, a copper infiltration method similar to that of the first embodiment is preferable.

In FIG. 8, the ceramic terminal member 8 is made of the same fired body of two or more layers of aluminum oxide or aluminum nitride as used in the second embodiment, and the metallized wiring layer 3c is provided with an external material. Terminal 4 is brazed. In the embodiment shown in FIG. 8, the ceramic terminal member 8 is joined to the side frame member 10 at both ends as free ends.
May have a rough dimensional accuracy. An optical semiconductor module is completed by mounting at least an optical semiconductor element and an optical fiber in a container in which the metal substrate 1, the side frame member 10, and the ceramic terminal member 8 are brazed, and then sealing with a sealing cover.

Also, in common with the first to fourth embodiments, if a continuous step is provided on the upper surface of the ceramic terminal member, it can be used as a guide on which the brazing material is to be placed or a brazing material in the brazing process of the portion. It becomes a runway to penetrate. A description will be given with reference to FIG. 10 taking the XX cross section of FIG. 3 as a plan view of the two-layer ceramic terminal member 3 of the first embodiment as an example. In the lower layer member 3a,
The metallized wiring layer 3c is applied and the external terminals 4 are brazed. Since a continuous step 3d is provided along the seal ring 5 and the side frame members 9 and 10 on the upper surface (a) of the upper layer member 3b, the step 3d and the seal ring 5 and the side frame members 9 and 1 are provided.
The V-shaped groove formed at 0 serves as a guide on which the brazing material is placed or a runner through which the brazing material permeates during the brazing process of the portion.

Further, if members having different coefficients of thermal expansion are present in the members constituting the package, there may be a problem in airtightness after brazing. If aluminum nitride is used for the ceramic terminal member 3 and a copper-tungsten alloy is used for the side frame member 2 formed by injection molding in a cylindrical shape, the coefficient of thermal expansion is 4.5 ×
Unlike 10 ⁻⁶ / deg and 8.3 × 10 ⁻⁶ / deg,
In some cases, poor airtightness may occur. However, the thickness between the ceramic terminal member 3 and the side frame members (2, 7, 9, 10) is not more than 0.1 mm.
It was found that by brazing with brazing material 11 having 0.1 mm silver solder placed on both sides of a thin copper plate of 2 mm or less, brazing material 11 functions as a cushion and eliminates poor airtightness.

Next, the form of the metal substrate 101 of the conventional package shown in FIG. 13 is changed to the substrate 1 of the first embodiment of the present invention.
To a package with each feature,
The results of comparative evaluation of the stability of the optical output by mounting the PD element, LD element, Peltier element, isolator, etc. shown in FIG. 11 and connecting an optical fiber will be described.

Referring to FIG. 11, various semiconductor devices housed in the optical semiconductor module 20 common to the product of the present invention and the conventional product will be described. The first insulating substrate 31 and the second
Peltier device 33 (6 × 6 mm) between insulating substrates 32
Are arranged on the metal substrate 1. Second insulating substrate 3
2. A PD element 35 for converting a light signal or an electric signal to each other by forming a semiconductor mounting area by superposing a mount substrate 34 on the
And a thermistor element 37 (set temperature 25 to 35 ° C.) for monitoring the control temperature of the LD element 36 and the Peltier element 33, and a lens 38 for correcting the optical axis of light. These various semiconductor devices are connected to the metallized wiring layer 3c attached to the ceramic terminal member 3 by bonding wires.

On the other hand, an isolator 39 for controlling the light passing direction is provided in the window 2b provided in the front frame 2a, and a light reflection from the optical fiber 40 causes the LD element 36 to generate noise in the connector 11 in the connector 11. In order to prevent this, a ferrule 41 whose end face is polished to 8 ° is fixed by YAG welding by laser beam irradiation.

Next, Table 1 shows a comparison of specifications between the optical semiconductor package of the present invention and the conventional optical semiconductor package.

[0038]

[Table 1]

After exposing both optical semiconductor modules 20 prepared according to the above specifications to a temperature cycle (-65 to 150 ° C.) test specified in MIL-STD-883C,
Light having a wavelength of 1.48 μm was injected at a full width at half maximum of FFP of ± 24 ° while being fixed to a heat sink having a thickness of 3 mm and a size of 200 × 300 mm, and the light output was measured by constant current driving.

The results are plotted in FIG. 12 by plotting the ambient temperature (° C.) on the horizontal axis and the light output (A.VdB) on the vertical axis. Although both are stable at an ambient temperature of 25 ° C., as the temperature conditions become more severe, the decrease in the optical output due to the misalignment of the optical axis due to the thermal distortion of the container that becomes apparent after the temperature cycle test is remarkable in the conventional product. It is. This phenomenon is caused by the fact that the side frame 2 of the product of the present invention is an injection-molded body and has few joints, the material of the ceramic terminal member 3 is aluminum nitride having a thermal conductivity nearly 10 times that of aluminum oxide, and the ceramic terminal member 3 Is brazed in the form of butting instead of fitting, so it is judged that uniform brazing material is injected, there is no deviation in heat capacity, heat dissipation is good and thermal distortion is suppressed. I do.

[0041]

According to the present invention, the combination of the side frame and the ceramic terminal member can be improved to a bonding mode which does not require strict control of the dimensional accuracy of both sides, and at the same time, the bonding portion can be omitted and the side which is a main component of the package can be reduced. By selecting a material having similar thermal conductivity for the frame and the ceramic terminal member, it is possible to provide an inexpensive optical semiconductor package and an optical semiconductor module with improved heat dissipation and less thermal distortion.

[Brief description of the drawings]

FIG. 1 is a three-dimensional view of an optical semiconductor package according to a first embodiment.

FIG. 2 is a three-dimensional view of a side frame of the first embodiment.

FIG. 3 is a plan view of the ceramic terminal member of the first embodiment.

FIG. 4 is a three-dimensional view of an optical semiconductor package according to a second embodiment.

FIG. 5 is a three-dimensional view of a side frame according to the second embodiment.

FIG. 6 is a three-dimensional view of an optical semiconductor package according to a third embodiment.

FIG. 7 is a three-dimensional view of a side frame according to the third embodiment.

FIG. 8 is a three-dimensional view of an optical semiconductor package according to a fourth embodiment.

FIG. 9 is a three-dimensional view of a side frame according to the fourth embodiment.

FIG. 10 is a sectional view of a two-layer ceramic terminal member of the present invention.

FIG. 11 is a cross-sectional view of an optical semiconductor module housed in a package.

FIG. 12 is a plot of light output corresponding to the ambient temperature of a product of the present invention and a conventional product.

FIG. 13 is a sectional view of a conventional optical semiconductor package.

[Explanation of symbols]

 1: Metal substrate 2, 7, 9, 10: Side frame member 3, 8: Ceramic terminal member 4: External terminal 5: Seal ring 6: Cover 11: Brazing material

Claims (7)

[Claims] 1. A package for housing an optical semiconductor element comprising a metal substrate on which an optical semiconductor element is mounted, a side frame member having means for supporting a ceramic terminal member and connecting an optical fiber, and a sealing cover, A package for an optical semiconductor element, characterized in that at least one end face in the longitudinal direction of the ceramic terminal member is joined as a free end not restricted by the side frame member. 2. The structure according to claim 1, wherein the upper surface of the ceramic terminal member is brought into contact with and joined to the metal seal member.
4. The package for an optical semiconductor device according to claim 1. 3. The package for an optical semiconductor device according to claim 1, wherein an upper surface and a lower surface of the ceramic terminal member are joined by being brought into contact with a notch of the side frame member. 4. The package for an optical semiconductor device according to claim 2, wherein a continuous step is provided on an outer peripheral edge of an upper surface of the ceramic terminal member. 5. The method according to claim 1, wherein a brazing material is placed on both surfaces of a thin metal plate having a thickness of 0.2 mm or less on a joining surface between the ceramic terminal member and the side frame member. The package for an optical semiconductor device according to any one of the above. 6. The side frame member is formed of a copper-tungsten alloy cylindrical body by a copper infiltration method, and the ceramic terminal member is formed of aluminum nitride. 4. The package for an optical semiconductor device according to claim 1. 7. An optical semiconductor module, wherein at least an optical semiconductor element and an optical fiber are mounted on the optical semiconductor element package according to claim 1.