JPH10104470A - Optical semiconductor package and method of manufacturing the same - Google Patents

Abstract

(57) [Problem] To provide an optical semiconductor package that can reliably fix an optical fiber fixing component directly on a surface of a corrosion-resistant plating layer by laser welding with high reliability. SOLUTION: A metal bottom plate 4 on which an optical semiconductor element is mounted,
A metal frame 2 surrounding the optical semiconductor element and having a window frame 7 for holding an optical fiber, wherein the metal frame 2 is joined to the metal bottom plate 4 to form an optical semiconductor package 1; , Palladium plating is applied to the outer surfaces of the metal bottom plate 4 and the metal frame 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical semiconductor package for accommodating and enclosing an optical semiconductor element in an airtight manner and for holding an optical fiber for exchanging optical signals with the optical semiconductor element, and a method of manufacturing the same. .

[0002]

2. Description of the Related Art An optical semiconductor device, such as a semiconductor laser device or a photodiode, is mounted inside and hermetically sealed.
FIG. 1 shows an example of an optical semiconductor package holding an optical fiber for exchanging optical signals with the optical semiconductor element.
Shown in Normally, the optical semiconductor element package 1 includes, as main components, a metal frame 2, a ceramic terminal 3, a metal bottom plate 4, a lead 5, a seal ring 6, and a cylindrical window frame 7 to which an optical fiber is attached. A metal lid (not shown) is hermetically attached to the upper end of the metal frame 2 via a seal ring 6.

[0003] The metal frame 2 forms the outer shape of the optical semiconductor package 1, stores internal components, and forms ceramic terminals 3.
And has a role as a base material for bonding optical fibers. The metal frame 2 is usually made of an Fe—Ni—Co alloy (commonly called Kovar).

The metal bottom plate 4 is used for the optical semiconductor package 1.
And a mounting portion 4a on which a cooling element for cooling an optical semiconductor element arranged in the center of the upper surface is mounted. At both ends of the metal bottom plate 4, screw holes 8 for attaching the optical semiconductor package 1 to an external member are provided. The metal bottom plate 4 is usually made of copper-
It is made of a tungsten alloy and has a function of efficiently radiating heat generated inside the optical semiconductor package 1 to the outside.

[0005] The assembly of the optical semiconductor package 1 is performed as follows. That is, the metal bottom plate 4 is brazed to the metal frame 2, generally silver brazing. Next, the metal bottom plate 4
A cooling element is mounted on the mounting portion 4a, an optical semiconductor element or the like is mounted thereon, the ceramic terminal 3 and each element are connected by a bonding wire, and a metal cover (not shown) is attached via a seal ring 6. Attach and seal hermetically.

In this optical semiconductor package 1, an optical fiber is attached to a window frame 7 (made of the same metal as the metal frame 2) via an optical fiber fixing part such as a flange (usually made of stainless steel). At this time, for example, the optical axis of the laser beam from the semiconductor laser element is accurately aligned with the optical axis of the optical fiber, and the flange is fixed to the window frame 7 by laser welding.

The exposed surface of the optical semiconductor package 1 is plated with Au with Ni plating as a base to prevent oxidation. Also, on the ceramic terminal 3,
Au plating is performed for Au wire bonding to the formed wiring pattern 3a. Further, the mounting portion 4a of the metal bottom plate 4 is plated with Au in order to ensure solderability when soldering the cooling element.

[0008]

However, if the optical semiconductor package 1 is plated with Au as described above, Au also adheres to the surface of the window frame 7 attached to the metal frame 2, so that Such problems arise. That is, in order to attach the optical fiber to the window frame 7 via the flange, the flange is laser-welded to the window frame 7. When the welded portion is irradiated with laser light, the laser light is applied to the exposed surface of the optical semiconductor package 1. The reflected Au plating layer makes laser welding difficult. Further, in spot welding using laser light, solidification of the molten portion proceeds in the order of the material having a higher melting point from the periphery of the molten portion, and finally Au having a relatively lower melting point is concentrated and solidified in the central portion of the molten portion. At this time, since Au has good thermal conductivity, the solidification speed from the outer periphery to the center of the spot weld is high, and internal stress is generated. For this reason, the material becomes brittle at the center where Au is concentrated, cracks occur,
Good bonding could not be achieved.

Therefore, the following measures have been taken.
1) After applying Au plating, the laser welded portion 7a of the window frame 7 (the end surface of the window frame 7) or, in some cases, the laser welded portion 7b (the end side surface of the window frame 7) by machining such as grinding. A
Remove u plating. 2) Alternatively, mask the laser welds 7a and 7b with a resist or the like in advance during Au plating, and
This masking is removed after u plating. 3) Alternatively, a member made of an insulator is attached to the tip of the window frame 7, and a metal part for laser welding is attached to the tip of the member to electrically insulate the window frame 7 from the metal part. Even if Au plating is applied to this metal part, Au plating is not applied to this metal part. 4) Only Ni plating is applied instead of Au plating. However, the first and second methods have a problem that the number of steps increases, the third method has a problem that the number of components increases, and the fourth method has a problem that wire bonding property and solder wettability decrease.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has as its object to fix an optical fiber firmly, and to perform an optical signal exchange between an optical semiconductor element and an optical fiber satisfactorily. It is to provide a semiconductor package.

[0011]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and comprises a metal bottom plate on which an optical semiconductor element is mounted, and a window frame surrounding the optical semiconductor element and holding an optical fiber. An optical semiconductor package formed by bonding the metal frame on the metal bottom plate, wherein the outer surfaces of the metal bottom plate and the metal frame are subjected to palladium plating. Is what you do.

The palladium plating layer has a lower laser light reflectance than the Au plating layer. Therefore, laser welding becomes possible even if the palladium plating layer exists in the laser welded portion. The thermal conductivity of the palladium plating layer is 70 W
/ M · K, which is 311 W / of the thermal conductivity of the Au plating layer.
Since it is as small as 1/4 or less of m · K, when the laser welded portion where the palladium plating layer exists is solidified, the solidification speed is slower than in the case where the Au plating layer is present, and the occurrence of cracks after solidification is suppressed. In addition, the reliability of laser welding is improved. From the above, when palladium plating is applied to the metal bottom plate of the optical semiconductor package and the outer surface of the metal frame, laser welding can be performed directly on the palladium plating layer, so that the palladium plating layer is partially formed. This eliminates the necessity for the work of removing the metal and masking at the time of plating. In addition, palladium has properties equivalent to Au in terms of corrosion resistance, wire bonding property, and solder wettability, and thus there is no problem in these points. Further, palladium is cheaper (about 1/4) than Au and is also superior in cost.

[0013]

Embodiments of the present invention will be described below. Over the entire outer surface of the optical semiconductor package shown in FIG. 1, on a Ni base plating layer having a thickness of 2 to 5 μm,
A 1 μm thick palladium plating layer was formed. When the YAG laser light (wavelength: 1.06 μm) was applied to the laser welds 7a and 7b of the optical semiconductor package to weld the optical fiber fixed part, it was possible to perform industrially sufficient welding. Although the reflectance of the YAG laser light by the Au plating layer was 90% or more, the reflectance of the YAG laser light by the palladium plating layer was about 50 to 60%.
e and Ni were comparable. No crack was observed when the portion melted by the YAG laser light was solidified. Furthermore, the palladium plating layer has corrosion resistance,
The wire bonding property and the solder wettability were equivalent to those of the Au plating layer. In the above embodiment, Ni is used as the base plating layer for improving the adhesion of the palladium plating layer, but Co may be used.

[0014]

As described above, according to the present invention, since the palladium plating is applied to the outer surfaces of the metal bottom plate and the metal frame, the optical fiber is directly laser-welded onto the plating layer without removing the plating layer. There is an excellent effect that the fixing component can be fixed with high reliability.

[Brief description of the drawings]

FIG. 1 is a perspective view of an optical semiconductor package.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical semiconductor element package 2 Metal frame 3 Ceramic terminal 3a Wiring pattern 4 Metal bottom plate 4a Placement part 5 Lead 6 Seal ring 7 Window frame 7a, 7b Laser welding part 8 Screw hole

Claims (3)

[Claims] 1. A metal bottom plate on which an optical semiconductor element is mounted, and a metal frame surrounding the optical semiconductor element and having a window frame for holding an optical fiber, wherein the metal frame is provided on the metal bottom plate. An optical semiconductor package formed by bonding palladium plating to an outer surface of a metal bottom plate and a metal frame body. 2. The optical semiconductor package according to claim 1, wherein the metal bottom plate is made of Cu @ W alloy, and the metal frame is made of Fe--Ni or Fe--Ni--Co alloy. 3. The optical fiber is fixed by applying palladium plating to the metal bottom plate and the outer surface of the metal frame, and then fixing the optical fiber fixing component to the window frame by laser welding. 3. The method for manufacturing an optical semiconductor package according to 1 or 2.