JP2000340876A - Optical semiconductor element package and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a package for optical semiconductor element at a low cost, which is satisfactory in heat release property, prevents short circuits due to sagging of a wire, and has high tensile strength of outer leads, and manufacturing method of the package. SOLUTION: This package is constituted of a metal frame 3 and a metal bottom plate 1 and provided with a case in which an optical semiconductor element is accommodated, a wiring board for inputting and outputting an electrical signal which is arranged at the position where the element does not exist in an immediately upper part and an immediately lower part in the case, and outer leads 5 led out to the outside via the sidewall of the metal frame 3. The wiring board is connected with the outer leads and connected with the element through wire bonding. The input and output of an electrical signal of the element to the outside are to be performed via the bonding wires, the wiring board and the outer leads.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a package for an optical semiconductor device and a method for manufacturing the same.

[0002]

2. Description of the Related Art As shown in a perspective view of FIG. 4 and a plan view of FIG. 5, a conventional package for an optical semiconductor device is fixed to a metal bottom plate 11 so as to form a housing above the metal bottom plate. It is mainly composed of the metal frame 13. On the metal bottom plate 11, an optical semiconductor device such as a semiconductor laser device and a Peltier device for cooling the semiconductor device are mounted.

Generally, the heat generated from an optical semiconductor device is
Cooled by the Peltier element arranged underneath,
Finally, it is discharged from the opposite surface of the Peltier element to the outside of the module through the metal bottom plate 11.

A metal frame 13 is provided with a window frame 14 to which an optical fiber is mounted, and a side portion of the metal frame 13 is provided with an electric signal input / output terminal 12. Pads 16 for bonding to the external leads 15 are provided outside the terminals 12, and pads 17 for wire bonding to an optical semiconductor element or the like arranged inside the housing are provided on the inside.

In the optical semiconductor device package having the above-described structure, if the distance between the bonding wires connecting the optical semiconductor device and the pads 17 is too long, a problem occurs due to the slack of the wires. 17
Are collected around the optical semiconductor element, unlike the pads 16 outside the housing.

That is, the pad 17 inside the housing also plays a role of converting the pitch of the wire. Further, if the bonding wires cross each other, there is a danger of a short circuit or the like.

If it is difficult to provide all the wiring on the surface layer of the wiring board, the wiring board (terminal) 12
Is often used as a multilayer substrate. A metal lid is attached to the upper side of the metal frame 13 so as to hermetically seal it.

The metal frame 13 is desirably made of a material whose thermal expansion coefficient is similar to that of the electric signal input / output terminal 12 mainly made of ceramic. As such a material, an Fe-Ni alloy or an Fe-Ni-Co alloy is used.

The electrical signal input / output terminals 12, which are mainly made of ceramic, are metal-bonded to the metal frame by brazing or the like. Therefore, as shown in FIG. 6, the metallization process is performed on the four joints (the A surface, the two C surfaces, and the D surface). Specifically, after W or the like is metallized on the pad surface B serving as an electrode and the upper and lower surfaces A and D of the terminal, it is cut to a predetermined length, and the cut surface C is subjected to a metallization process such as Mo-Mn. There are many.

For the metal bottom plate 11, a material having a thermal expansion coefficient close to that of the metal frame 13 and having a high thermal conductivity is used because it is necessary to quickly dissipate heat generated by a semiconductor laser device or the like. There is a need. As such a material, a Cu-W alloy or the like is used. The metal frame 13 and the metal bottom plate 11 are joined by a brazing material.

[0011]

As described above, the conventional optical semiconductor device packages shown in FIGS.
The electric signal input / output terminals 12 mainly made of ceramics such as alumina need to be attached to the metal frame 13 so as to maintain airtightness. Must be fitted with tight dimensional tolerances. However, there is a problem that it is not easy to machine and finish the terminal 12 mainly made of ceramic after the first step with a very tight dimensional tolerance, resulting in a very high cost.

In addition, over four surfaces other than the pad surface (A surface, two C surfaces, and D surface), and as described above,
It is costly to perform the metallization process separately.

In order to avoid such a problem, a wiring board for inputting and outputting an electric signal is arranged inside the metal frame 13,
It is also conceivable that the external lead 15 is led out through a through hole 18 provided on the side surface of the metal frame 13 and the through hole 18 is sealed with a sealing material such as a glass material.

For this purpose, it is necessary to form a joint between the external lead 15 and the wiring board existing outside the metal frame 13 inside the metal frame 13. However, since the optical semiconductor module is required to be reduced in size, it is not possible to use a metal frame 13 at least larger than a conventional package for an optical semiconductor element to increase the space inside the metal frame 13.

On the other hand, from the viewpoint of reliable heat dissipation of the heat generated from the optical semiconductor element, the thermal resistance between the optical semiconductor element, the Peltier element, and the metal bottom plate 11 serving as a heat radiation route must be reduced as much as possible. A wiring board with poor heat conduction cannot be interposed between them. Further, it is necessary to maintain an optical system for reliably transmitting light emitted from the optical semiconductor element to the optical fiber.

Further, the wiring board is eliminated, and the external leads 15 are removed.
It is conceivable that wire bonding is directly performed between the semiconductor chip and the optical semiconductor element, but in this case, since the pitch of the external leads 15 is not converted, the bonding length is increased, and it is easy to cause inconvenience such as short-circuit due to dripping of the wire. There's a problem.

Therefore, a wiring board for pitch conversion must be formed inside the metal frame 13. But,
There is no package for an optical semiconductor device that has attained the above-mentioned effects while satisfying the above-described constraints.

The present invention has been made in view of the above problems, and has as its object to provide a low-cost package for an optical semiconductor device which has good heat dissipation and prevents short-circuiting due to dripping of wires.

It is another object of the present invention to provide a method for manufacturing the above-mentioned package for an optical semiconductor device.

[0020]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a housing including a metal frame and a metal bottom plate, in which an optical semiconductor element is housed, and an inside of the housing, directly above the housing. And a wiring board for electric signal input / output arranged at a position immediately below the optical semiconductor element, and an external lead led out through a side wall of the metal frame, wherein the wiring board is , Connected to the external lead, and connected to the optical semiconductor element by the wire bonding. Input and output of an electric signal to and from the outside of the optical semiconductor element are performed through the bonding wire, the wiring board, and the external lead. The present invention provides an optical semiconductor device package characterized by being carried out.

In this case, the wiring board can be formed of a glass ceramic material. In the above-described package for an optical semiconductor element, the wiring substrate may have a configuration in which an upper electrode has an upper electrode for wire bonding with the optical semiconductor element on an upper surface, and a lower electrode for bonding to an external lead on a lower surface. In addition, a configuration in which a spacer is arranged between the metal bottom plate of the housing and the wiring board can be adopted.

The spacer can be formed as a part of the metal frame or the metal bottom plate. Further, the external lead can be led out through a through hole provided on the side surface of the metal frame, and the periphery of the external lead in the through hole can be sealed with a sealing material made of a glass material or the like.

According to the present invention, there is provided a method of manufacturing a package for an optical semiconductor device as described above, wherein the spacer is formed integrally with the metal frame or metal bottom plate by metal injection molding. Provided is a method for manufacturing a package for a semiconductor device.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an optical semiconductor device package according to an embodiment of the present invention, FIG. 2 is a plan view thereof, and FIG. 3 is a sectional view taken along line AA of FIG. As shown in FIGS. 1 to 3, the package for an optical semiconductor device mainly includes a metal bottom plate 1 and a metal frame 3 fixed to form a housing on the metal bottom plate 1. . On the metal bottom plate 1, an optical semiconductor device such as a semiconductor laser device and a Peltier device for cooling the semiconductor device are mounted. The heat generated from the optical semiconductor element is cooled by the Peltier element disposed under the optical semiconductor element, and is finally discharged from the opposite surface of the Peltier element to the outside of the module through the metal bottom plate 1.

Spacers 9 made of the same material as the metal bottom plate 1 or the metal frame 3 are provided on the metal bottom plate 1 at the four corners in the housing. On these spacers 9, an electric signal input made of an inorganic material is provided. An output wiring board 2 is arranged. The spacer 9 may be formed as a part of the metal bottom plate 1 or the metal frame 3, that is, integrally with the metal bottom plate 1 or the metal frame 3. The integral formation can be performed by, for example, metal injection molding (MIM).

A pad 6 for bonding to an external lead 5 is provided on the upper or lower surface of the wiring board 2, and a pad 7 for wire bonding with the optical semiconductor element is provided on the upper surface. The optical semiconductor element is connected to the pad 7 by a bonding wire. A through hole 8 is formed in the side surface of the metal frame 3, and the external lead 5 connected to the pad 6 is led out through the through hole 8. In this way, the input and output of electric signals to and from the outside of the optical semiconductor element are performed via the bonding wires, the wiring board 2 and the external leads 5.

The through hole 8 formed in the side surface of the metal frame 3
Is sealed with a sealing material made of a glass material or the like, whereby the airtightness of the housing made of the metal frame 3 and the metal bottom plate 1 is maintained.

The metal frame 3 is provided with an optical fiber attaching window frame 4 to which an optical fiber is attached. The window frame 4 is made of the same material as the metal frame 3 and may be attached by brazing or soldering, but may be formed integrally with the metal frame 3 by injection molding or the like.

The metal frame 3 is desirably made of a material whose thermal expansion coefficient is close to that of the electric signal input / output wiring board 2 mainly made of a ceramic material or a glass ceramic material. As such a material, an Fe-Ni alloy or an Fe-Ni-Co alloy is used.

For the metal bottom plate 1, a material having a thermal expansion coefficient close to that of the metal frame 3 and having a high thermal conductivity is used because it is necessary to quickly dissipate heat generated by a semiconductor laser device or the like. There is a need. As such a material, a Cu-W alloy or the like is used. The metal frame 3
And the metal bottom plate 1 are joined by a brazing material. Metal frame 3
A metal lid is attached to the upper side of the housing so as to hermetically seal it.

In the optical semiconductor device package of the present invention configured as described above, an electric signal input / output wiring board 2 made of an inorganic material is arranged inside a housing made of a metal frame 3 and a metal bottom plate 1. are doing. Therefore, the dimensional tolerance of the wiring board can be reduced as compared with the conventional optical semiconductor element package in which the electric signal input / output terminal 2 is fitted into a part of the housing. Therefore, for example, it is possible to use the wiring board 2 which has been sintered and has no post-processing or has been slightly post-processed, so that there is an advantage that the manufacturing cost can be reduced.

Further, at most two metallization processes are required, and in particular, only one surface is required for bonding, and both are completed simultaneously in one process, so that the cost is low.

Further, by providing the pads 6 on the lowermost surface of the wiring board 2 and joining the pads 6 to the external leads 5, the wiring board 2 can be arranged even in a limited narrow space.

Further, by providing a spacer 9 between both ends of the wiring board 2 and the metal bottom plate 1 and supporting the wiring board 2 by the spacer 9, even if the rigidity of the external lead is low and the external lead is easily bent, It is possible to prevent the external leads from being deformed due to the impact at the time of wire bonding and the wiring board 2 from being tilted.

Further, since it is often necessary to provide a grounding portion in the electric wiring, it is desirable that the spacer 9 be made of a metal material. Further, the spacer 9 is metal-bonded to the wiring board 2 and at least the metal frame 3 or It is desirable to make a metallic connection with the metal bottom plate 1.

The wiring board for inputting and outputting electric signals can be made of a ceramic material mainly composed of alumina. However, in order to improve the propagation characteristics of high-frequency signals, a glass ceramic material (also called a low-temperature fired ceramic) is used. Yes)
It is desirable to be constituted by.

The glass ceramic is a composite material of a glass material such as borosilicate glass and a ceramic material such as alumina. Since the amount of alumina having a relatively high dielectric constant is small, the dielectric constant is low. Temperature is 1000 ℃
Therefore, Cu and A, which have excellent conductivity, are used as wiring layers instead of W used in conventional ceramic terminals.
g can be used. Therefore, it is possible to provide an electric signal input / output terminal with improved propagation characteristics of a high-frequency signal.

Further, glass ceramics can be fired in the air if the firing temperature is low and a metal such as Ag or Ag-Pd is used as the conductor material.
It is also possible to obtain a low-cost electric signal input / output terminal.

However, this glass ceramic is
If a heat history of 500 ° C. or more is received by brazing or the like, there is a disadvantage that the strength is reduced. Therefore, when a terminal (wiring board) made of glass ceramic is used for a conventional package for an optical semiconductor element, when a tensile stress is applied to the external lead 15, the terminal 12 itself is damaged, and as a result, the required external lead is used. Has a problem that the tensile strength of the steel cannot be maintained.

On the other hand, in the optical semiconductor device package of the present invention, after the external lead 5 is inserted into the through hole 8 provided in the metal frame 3, the gap around the external lead 5 is made of glass material or the like. Even when stress is applied to the external leads 5 by sealing with a sealing material, the sealing of the through holes 8 in the metal frame 3 is not performed at the bonding portion with the wiring substrate 2 for inputting and outputting electric signals. Since this stress is received by the stopping portion, even if the bonding strength between the external lead 5 and the wiring board 2 is reduced due to the brittleness of the wiring board 2 from the initial state, a large stress is applied to that portion. Therefore, the tensile strength of the external lead 5 can be maintained.

Further, by sealing the through hole 8 into which the external lead is inserted, the external lead 5 is led out to the outside without being short-circuited to the metal housing, and the metal frame 3 and the metal The airtightness of the housing made of the bottom plate 1 can be maintained.

Therefore, by using the package for an optical semiconductor device of the present invention, it is possible to use the electric signal input / output wiring board 2 made of a glass-ceramic material having excellent high-frequency characteristics. It is also possible to provide a package for an optical semiconductor device.

Although the spacer between the wiring board 2 and the metal bottom plate 1 can be manufactured as an independent member, it is preferable that the spacer is formed as a part of the metal frame 3 or the metal bottom plate 1. Is preferable in terms of cost. In particular,
If the metal frame 3 is manufactured by metal injection molding (MIM), the cost for the spacer 9 can be neglected by forming a mold integral with the spacer 9, and the advantage is further increased. ,preferable.

As described above, the present invention satisfies all of the conditions required for a package for an optical semiconductor device and makes it possible to provide an inexpensive package for an optical semiconductor device.

[0045]

EXAMPLES Examples of the present invention will be shown below to explain the effects of the present invention more specifically. Example 1 Metal bottom plate 1 made of Cu-W, Kovar (Fe-29N)
i-17Co (wt%)), a metal frame 3 having a through hole 8, an optical fiber mounting window frame 4 made of Kovar, and mainly made of alumina, a predetermined portion of which is W-metallized and plated with Ni. Wiring board 2 made of layers,
A spacer 9 made of Kovar and a lead frame for forming the external lead 5 were prepared.

Of these components, each member except the external lead 5 was set on a carbon jig, and assembled by brazing with Ag under a hydrogen atmosphere at 800 ° C. That is, the metal bottom plate 1 is joined to the metal frame 3, the spacer 9 is joined to the metal bottom plate 1 at the four corners of the metal frame 3, the wiring board 2 is joined to the spacer 9, and the metal frame 3 Window frame 4 for mounting optical fiber
Was joined. A Cu-Ag eutectic alloy was used as the brazing material. The structure obtained in this manner was subjected to Ni plating and Au plating, and then the window sealing portion of the optical fiber mounting window frame 4 and the mounting of the external leads 5 were performed. The Au plating of the planned portion was removed, while the lead frame for forming the Au-plated external leads and the window for maintaining the airtightness of the optical fiber mounting window 4 were set in another carbon jig. .

Next, low melting point glass (PbO.SiO ₂ type) is disposed in the through hole 8 of the metal frame 3 and the window sealing portion, and Ag-C is provided between the external lead 5 and the wiring board 2.
Placing u-Sn brazing material foil in a nitrogen atmosphere
By performing a heat treatment at 0 ° C., the external leads 5 were joined to the wiring board 2, and the through holes 8 on the side surfaces of the metal frame 3 and the optical fiber mounting window frame 4 were hermetically sealed.

A predetermined internal component was mounted on the package thus obtained, and the package was covered with the package. The package was hermetically sealed to obtain an optical semiconductor module. When this optical semiconductor module was operated, there was no problem.

Example 2 A metal frame 3 made of Kovar, in which a spacer equivalent portion is integrally formed by MIM, a metal bottom plate 1 made of Cu-W, a lead frame for forming external leads 5 made of Kovar, and PbO.B ₂ A wiring board 2 made of glass ceramic composed of O ₃ · SiO ₂ glass and alumina in a weight ratio of 40:60, and metallized on both surfaces thereof was prepared.

After the metal frame 3 and the metal bottom plate 1 are brazed by eutectic Ag brazing, the wiring board 2 and the spacer portions 9 of the metal frame 3 are Au-bonded in a nitrogen atmosphere at 400 ° C. using a carbon jig. Wiring board 2 and external leads 5 are made of Si eutectic alloy
Are respectively brazed with an Au-Si eutectic alloy, and the window sealing portion of the window frame 4 for attaching the optical fiber and the through hole 8 on the side surface of the metal frame 3 are made of low melting glass (Pb
(O.B ₂ O ₃ system).

When the lead of the package obtained in the same manner as that of the package manufactured in the same manner as above and the through-hole 8 was not sealed with glass was pulled, the tensile strength of the former was about 30 kgf / mm ^2. While the latter showed sufficient tensile strength, the latter had only 5 kgf / mm ² and did not show sufficient tensile strength.

Therefore, it is confirmed that the stress applied to the joint between the wiring board and the lead can be reduced by forming the through-hole 8 in a glass-sealed structure, so that sufficient tensile strength can be provided. Was done.

Example 3 In the same manner as in Example 1, the packages shown in FIGS. FIG. 7 is a perspective view of a package according to the present embodiment,
FIG. 8 is a plan view, and FIG. 9 is a sectional view taken along line BB of FIG.

In the package according to the first embodiment shown in FIGS. 1 to 3, a bonding pad 6 for connecting to an external lead 5 has a pad 7 for wire bonding with an optical semiconductor element on the lower surface of the electric signal input / output wiring board 2. 7 to 9, the bonding pads 6 for bonding to the external leads 5 and the pads 7 for wire bonding to the optical semiconductor element are both formed on the upper surface. It is formed on the upper surface of the substrate 2.

A predetermined internal component was mounted on the package thus obtained, and the package was capped. The package was hermetically sealed to obtain an optical semiconductor module. When this optical semiconductor module was operated, there was no problem.

In the package shown in FIGS. 7 to 9, if the wiring space is insufficient and the wiring connecting the pads 6 and 7 cannot be formed on the substrate, the wiring can be formed by wire bonding.

Example 4 In the same manner as in Example 1, the package shown in FIGS. 10 to 12 was manufactured. FIG. 10 is a perspective view of the package according to the present embodiment, FIG. 11 is a plan view, and FIG. 12 is a cross-sectional view taken along line CC of FIG.

In the package shown in FIGS. 10 to 12, two electric signal input / output substrates 2 on the right and left sides are usually connected and integrated at the rear part of the package.
That is, the electric signal input / output substrate 2 has a U-shape.

As described above, the package shown in FIGS. 10 to 12 can be provided with pads for wire bonding with an optical semiconductor or the like at the rear in addition to the left and right sides of the optical semiconductor element, so that the wiring of the module is easy. It has the advantage that it becomes.

[0060]

As described in detail above, according to the present invention, it is possible to provide a package for an optical semiconductor device which satisfies required characteristics and is less expensive than the conventional one. Further, by using a wiring board made of glass ceramic, it is possible to provide a package for an optical semiconductor element having excellent high-frequency signal propagation characteristics.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an optical semiconductor element package according to an embodiment of the present invention.

FIG. 2 is a plan view showing an optical semiconductor device package according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view of the optical semiconductor device package according to one embodiment of the present invention, taken along line AA of FIG. 2;

FIG. 4 is a perspective view showing a conventional package for an optical semiconductor element.

FIG. 5 is a plan view showing a conventional package for an optical semiconductor element.

FIG. 6 is a perspective view showing electric signal input / output terminals in a conventional optical semiconductor element package.

FIG. 7 is a perspective view showing an optical semiconductor element package according to another embodiment of the present invention;

FIG. 8 is a plan view showing an optical semiconductor device package according to another embodiment of the present invention.

FIG. 9 is a sectional view taken along the line BB of FIG. 8, showing an optical semiconductor element package according to another embodiment of the present invention.

FIG. 10 is a perspective view showing an optical semiconductor element package according to still another embodiment of the present invention.

FIG. 11 is a plan view showing an optical semiconductor device package according to still another embodiment of the present invention.

FIG. 12 is a cross-sectional view of a package for an optical semiconductor device according to still another embodiment of the present invention, taken along line CC of FIG. 11;

[Explanation of symbols]

1, 11: Metal bottom plate 2, 12: Electric signal input / output terminal (electric signal input / output wiring board) 3, 13: Metal frame 4, 14 ... Optical fiber mounting window frame 5, 15: External lead 6, 16 Pad for external lead bonding 7, 17 Pad for wire bonding 8, 18 ... Through hole 9 ... Spacer

Claims (7)

[Claims] 1. A housing comprising a metal frame and a metal bottom plate, in which an optical semiconductor element is accommodated, and which is disposed in a position inside the housing immediately above and immediately below the optical semiconductor element. A wiring board for inputting / outputting an electric signal, and an external lead led out through a side wall of the metal frame. The wiring board is connected to the external lead, and the optical board is connected to the external lead by wire bonding. An optical semiconductor element package connected to a semiconductor element, wherein input and output of electric signals to and from the outside of the optical semiconductor element are performed via these bonding wires, a wiring board, and external leads. 2. The wiring board has a first electrode on an upper surface and a second electrode on a lower surface, wherein the first electrode is wire-bonded to the optical semiconductor element, and the second electrode is 2. The package for an optical semiconductor device according to claim 1, wherein the package is bonded to the external lead. 3. The wiring board has a first electrode on an upper surface and a second electrode on a lower surface, wherein the first electrode is wire-bonded to the optical semiconductor element, and the second electrode is The optical semiconductor device package according to claim 1, wherein a spacer is joined to the external lead, and a spacer is arranged between the metal bottom plate of the housing and the wiring board. 4. The package for an optical semiconductor device according to claim 1, wherein said wiring board is formed of a glass ceramic material. 5. The package for an optical semiconductor device according to claim 1, wherein the spacer is formed as a part of the metal frame or a metal bottom plate. 6. The external lead is led out through a through hole provided in a side surface of the metal frame, and a periphery of the external lead in the through hole is sealed with a sealing material made of a glass material or the like. The package for an optical semiconductor device according to claim 1, wherein: 7. The method of manufacturing a package for an optical semiconductor device according to claim 5, wherein the spacer is formed integrally with the metal frame or the metal bottom plate by metal injection molding. A method for manufacturing a package for a semiconductor element.