JPH05299534A - Stem for semiconductor device - Google Patents

Abstract

PURPOSE:To provide the title stem for semiconductor device both in excellent solderability and wirebondability. CONSTITUTION:Within the title stem for semiconductor device comprising a metallic outer annulus implanted with lead wire through the intermediary of glass, the first layer 12 comprising electrolytic nickel plating film, the second layer 14 comprising non-electrolytic nickel boron or non-electrolytic nickel phosphorus plating film and the third layer 16 comprising Au film 1Angstrom -100Angstrom thick or palladium or palladium alloy film 100Angstrom -1000Angstrom thick are successively formed on the metallic outer annulus 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device stem.

[0002]

BACKGROUND ART A stem for a semiconductor device is subjected to various functional platings in order to improve solderability or wire bondability of a semiconductor element mounted on the stem. Conventionally, as this type of functional plating, electroless nickel phosphorus plating is applied to the first layer and silver plating is applied to the second layer,
Alternatively, it is known that the first layer is electrolytic nickel plated and the second layer is gold plated. However, the former one has a problem of silver migration, and the latter one has a problem that the cost rises because gold is expensive. Therefore, the inventor has studied a stem for a semiconductor device in which the first layer is electrolytic nickel plating and the second layer is electroless nickel boron plating, but it is found that although the wire bonding property is excellent, there is a problem in solderability. did.

[0003]

SUMMARY OF THE INVENTION Therefore, the present invention has been made to solve the above problems, and an object of the present invention is to provide a stem for a semiconductor device which is excellent in solderability and wire bondability. ..

[0004]

The present invention has the following constitution in order to achieve the above object. That is, in a stem for a semiconductor device in which a lead wire is implanted in a metal outer ring via glass, in the metal outer ring, the first layer is an electrolytic nickel plating film and the second layer is an electroless nickel boron or Electrolytic nickel-phosphorus plating film, the third layer has a thickness of 1Å ~ 100Å
The semiconductor device stem, wherein the gold film or the palladium or palladium alloy film having a thickness of 100Å to 1000Å is sequentially formed.

[0005]

[Function] Any of the gold coating, the palladium coating, and the palladium alloy coating has good solder wettability and is excellent in solderability of semiconductor elements. Soldering of the semiconductor element can be favorably carried out in a reducing atmosphere without using a flux or under the use of a weakly active flux without influence of the flux. And the third layer coating 16
By forming the film extremely thin, the characteristics of the underlying film can be brought out. Substrate, that is, second layer film 1
The electroless nickel boron plating film or the electroless nickel-phosphorus plating film 4 is excellent in wire bonding property, and even if the third layer 16 is present, this property is taken out as it is because the third layer is extremely thin. Good wire bondability can be obtained with both gold wire and aluminum wire. As described above, the semiconductor layer stem 10 according to the present invention is excellent in solderability, wire bondability, and corrosion resistance of the semiconductor element. When the second layer is an electroless nickel boron plating film, even if the cap is laser-welded, cracks do not occur in the welded portion, and the laser weldability and cap sealing property are excellent.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows a metal outer ring 10 of a stem for a semiconductor device. Although not shown, a lead wire is insulated and planted with glass in a through hole for lead attachment formed through the upper and lower surfaces of the metal outer ring 10. Further, a semiconductor element is soldered and fixed to the upper surface of the metal outer ring 10, and a cap is hermetically sealed to cover the semiconductor element and used as a semiconductor device. The metal outer ring 10 is formed with a three-layer metal film including a first layer 12, a second layer 14, and a third layer 16. First
The layer coating 12 is an electrolytic nickel-plated coating for improving corrosion resistance. The thickness is not particularly limited, but about 0.1 μm to 10 μm is preferable. The second layer film 14 is an electroless nickel boron or electroless nickel phosphorous plating film for improving the wire bonding property. The thickness of the second layer coating 14 is about 0.1 μm to 10 μm, preferably 1.5 μm to
The thickness of 2 μm is preferable from the viewpoint of wire bondability. When the cap is fixed by laser welding, if the second layer film is an electroless nickel phosphorous plating film, cracks may occur in the welded portion,
In this case, an electroless nickel boron plating film is preferable. The third layer film 16 is a gold film having a thickness of 1Å to 100Å or a palladium or palladium alloy film having a thickness of 100Å to 1000Å. A palladium-nickel alloy is suitable as the palladium alloy. The third layer film 16 may be formed by any method such as electrolytic plating, electroless plating, displacement plating, and vapor deposition. It is a feature of the present invention that the thickness of the third layer film 16 is extremely thin, such as 1Å to 100Å and 100Å to 1000Å as described above. Gold coating, palladium coating or palladium alloy coating has good solder wettability, and even if it is extremely thin as described above, this property is maintained.
Excellent solderability for semiconductor devices. Soldering of the semiconductor element can be favorably carried out in a reducing atmosphere without using a flux or under the use of a weakly active flux without influence of the flux. By forming the third layer film 16 extremely thin as described above, the characteristics of the underlying film can be obtained. The underlayer, that is, the electroless nickel boron or electroless nickel phosphorous plating film as the second layer film 14 is excellent in wire bonding property as described above, and this characteristic is the third layer 16
Even if there is, the third layer is extracted as it is because it is extremely thin. Good wire bondability can be obtained with both gold wire and aluminum wire. As described above, the semiconductor layer stem 10 according to the present invention is excellent in solderability, wire bondability, and corrosion resistance of the semiconductor element. Further, when the second layer is an electroless nickel boron plating film, even if the cap is laser-welded, cracks do not occur in the welded portion, laser weldability,
Excellent cap sealing property.

Table 1 shows the constitution and characteristics of the coating.

[Table 1]

As is clear from Table 1, Examples 1, 2 and
All of 3 are excellent in solderability of semiconductor elements (chips), wire bondability, and laser weldability of caps. The case of Comparative Example 2 is also good, but the gold coating is used in Example 1.
Is thicker than 0.1 μm to 10 μm, the solder tends to flow too much, and the cost becomes high. In the case of Comparative Example 3, there is a problem of migration due to silver. When the electroless nickel phosphorous plating film was formed on the second layer, there was a problem in the laser weldability of the cap, but the solderability and wire bondability of the semiconductor element were good. There is no problem if the cap is sealed by another method such as brazing.

[0009]

According to the stem for a semiconductor device of the present invention, the gold coating, the palladium coating or the palladium alloy coating of the third layer has good solder wettability, excellent solderability of the semiconductor element, and reducing property. It is possible to perform good soldering without the effect of flux without using flux or by using weakly active flux by performing it in an atmosphere, and by forming a very thin third layer film, The properties of the film can also be extracted. Groundwork,
That is, the electroless nickel boron or electroless nickel phosphorous plating film as the second layer film is excellent in wire bonding property, and even if the third layer is present, this property is taken out as it is because the third layer is extremely thin, and the wire bonding is performed. Excellent in performance. As described above, the semiconductor layer stem according to the present invention is excellent in solderability, wire bondability, and corrosion resistance of the semiconductor element.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a coating structure of a stem.

[Explanation of symbols]

 10 Metal Outer Ring 12 First Layer 14 Second Layer 16 Third Layer

Claims (1)

[Claims] 1. A stem for a semiconductor device in which a lead wire is planted on a metal outer ring via glass, wherein the metal outer ring has a first layer of electrolytic nickel plating film,
The second layer is formed by sequentially forming an electroless nickel boron or electroless nickel phosphorus plating film, and the third layer is formed by sequentially forming a gold film having a thickness of 1Å to 100Å or a palladium or palladium alloy film having a thickness of 100Å to 1000Å. Stem for semiconductor devices.