JPH0787233B2 - Electronic component having a gold conductive layer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electronic component having a gold conductive layer on a metal surface, and more particularly to a semiconductor element storage package for storing a semiconductor integrated circuit element and a multilayer wiring. The present invention relates to improvement of a base metal layer of a gold conductive layer in an electronic component such as a substrate.

[Conventional technology]

Gold has (i) high conductivity, (ii) good oxidation resistance, (ii)
i) High resistance to discoloration (thigh color resistance), (iv) Excellent in that it can be easily alloyed with silicon (Si) of a semiconductor chip to form an Au-Si eutectic alloy and exhibit a strong joint strength. It is widely used in various electronic parts due to its physical properties. For example, in a semiconductor element housing package for housing a semiconductor integrated circuit element, a die attach portion for mounting the semiconductor integrated circuit element, a wire for connecting an electrode of the semiconductor integrated circuit element and an external lead terminal are mounted. There is a wire bonding portion or an external lead terminal for connecting the semiconductor integrated circuit element to an external electric circuit. These are tungsten (W), molybdenum (Mo),
External lead made of a metal plate such as Kovar (Fe-Ni-Co) or 42Alloy attached to a metal surface metallized with a refractory metal such as manganese (Mn) or a brazing material on the metallized metal surface. It is formed on the surface of the terminal by plating, vapor deposition, sputtering or the like.

However, for example, when a gold layer deposited on the surface of an external lead terminal is brazed and bonded to a package for storing a semiconductor element to an external electric circuit via solder or the like, the gold layer is a molten solder (Sn- Pb alloy) is very quickly dissolved, and as a result, the brazing material such as solder directly contacts the external lead terminal made of 42Alloy or Kovar metal, which has poor reactivity (wettability) with the solder, It was difficult to firmly bond the semiconductor element housing package to the external electric circuit.

Therefore, in order to eliminate such drawbacks, a metal layer of nickel (Ni), which hardly dissolves in molten solder and has good reactivity (wettability) with solder, is coated as a base of the gold conductive layer. Is proposed.

However, the nickel metal layer coated as an underlayer of the gold conductive layer is formed by heating when mounting a semiconductor integrated circuit device in a package for housing a semiconductor device, or when hermetically sealing the package. Easily diffuses into the surface of the conductive layer of gold and is oxidized to form nickel oxide or hydroxide, which has extremely poor reactivity (wettability) with solder. However, it is difficult to attach the semiconductor element housing package to the external electric circuit, and further, there is a problem that the surface of the gold conductive layer is discolored and at the same time the conductivity is deteriorated.

Therefore, in order to eliminate such a drawback, the applicant previously proposed to provide a metal layer of cobalt, which is extremely slow in heat diffusion from nickel to gold, as a base of the gold conductive layer.

[Problems to be solved by the invention]

However, when a metal layer made of cobalt is formed as an underlayer of the gold conductive layer, formation of cobalt oxide, hydroxide, etc., which has poor reactivity (wettability) with solder on the gold conductive layer surface is small. If a burn-in test (a test to check the characteristic change by adding high temperature heat history to the semiconductor integrated circuit element) is performed to check the characteristics of the semiconductor integrated circuit element,
Tin (Sn) contained in the solder unilaterally diffuses through the gold conductive layer to the underlying metal layer made of cobalt, and as a result, when mounting the semiconductor element storage package to an external electric circuit, etc. It was found that the external lead terminal and the solder are easily separated from each other by the mechanical stress applied to the external lead terminal from the outside, and the reliability of the electrical connection is lowered.

[Object of the Invention]

The present invention has been devised in view of the above-mentioned drawbacks, and its purpose is to prevent solder tin from diffusing into a metal layer made of cobalt even if a burn-in test for checking a semiconductor integrated circuit element is performed. Even if stress is applied, peeling does not occur in the joint between the metallized metal layer provided on the insulating substrate and the external lead terminal and the solder, and furthermore, when the semiconductor integrated circuit element is mounted or after it is hermetically sealed. To provide an electronic component having a gold conductive layer that does not deteriorate in reactivity (wettability) with a brazing material even when heat is applied during heating and the like and is exposed to oxidizing conditions such as high temperature and high humidity. It is in.

[Means for solving problems]

The present invention relates to an electronic component having a gold conductive layer on a metal surface, and cobalt 98.5 to 99.999 is used as a base of the gold conductive layer.
The present invention is characterized in that a metal layer made of an alloy containing 0.001 to 1.5% by weight of sulfur and 0.001 to 1.5% by weight of sulfur is provided.

When the sulfur content of the present invention is less than 0.001% by weight, tin contained in the solder cannot be effectively prevented from diffusing into cobalt in the underlying metal layer, and solder peeling occurs. Also,
If its content exceeds 1.5% by weight, the corrosion resistance of the underlying metal layer deteriorates, which is not preferable.

〔Example〕

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.

FIG. 1 is a partially cutaway plan view showing an electronic component of the present invention as an example of a package for housing a semiconductor element with leads,
FIG. 2 is an enlarged cross-sectional view of the main part of FIG.

In the figure, 1 is an insulating substrate made of an electrically insulating material such as ceramic or glass, and 2 is attached a wire 11 for electrically connecting an electrode of the semiconductor integrated circuit element 10 and an external lead terminal 12 to each other. It is a metallized metal layer for wire bonding.

A part of the metallized metal layer 2 extends to the side surface of the insulating base 1, and the external lead terminal 12 is joined to the side surface of the insulating base 1 via a brazing material or the like. 3 is a metallized metal layer of a die attach portion for mounting the semiconductor integrated circuit element 10. Immediately above the metallized metal layers 2 and 3 and the external lead terminals 12, metal layers 4,5 and 6 made of an alloy of cobalt and sulfur, and on top of them, gold conductive layers 7, 8 and 9, respectively. It is set up. A for the gold conductive layer 8
The semiconductor integrated circuit element 10 is attached via a brazing material such as u-Si, and each electrode of the semiconductor integrated circuit element 10 is a wire.
It is electrically joined to the gold conductive layer 7 via 11 and is led to the external lead terminal 12.

The metallized metal layers 2 and 3 are formed by printing and coating a metal paste obtained by adding a suitable organic solvent to a powder of tungsten, molybdenum, manganese, or the like, and a solvent to the insulating substrate 1 by a well-known thick film method, and thereafter. It is formed by baking at high temperature and metallizing.

The external lead terminals 12 are Kovar (Fe-Ni-Co), 42Al.
Each metal layer 4,5,6,7,8,9 made of a metal such as loy and made of a cobalt-sulfur alloy and gold is formed by a technique such as plating, vacuum deposition, and sputtering.

Further, a lid 13 made of an electrically insulating material such as ceramic or glass is attached to the upper surface of the insulating substrate 1 via a sealing member such as glass or resin. The void is completely airtightly sealed from the outside air, and becomes a semiconductor device as a final product.

Thus, according to the invention, on the surface of the external lead terminal,
By providing a metal layer made of an alloy of cobalt and sulfur, which is hard to form a solid solution with gold and does not diffuse tin, on the base of the gold conductive layer, the adhesion strength between the solder and the external lead terminal is increased, There is no occurrence of peeling between the external lead terminals and the solder due to the application of an external force, and heat is applied when the semiconductor integrated circuit element is attached, or when hermetically sealing after attachment, In addition, even if exposed to oxidizing conditions such as high temperature and high humidity, it does not generate oxides or hydroxides that have poor reactivity (wettability) with the brazing material, making the package for storing semiconductor elements strong in external electrical circuits. Can be attached.

The present invention is not limited to the above-described embodiments, and is applicable to, for example, a leadless package for storing a semiconductor integrated circuit element (chip carrier), an electronic portion having a gold conductive layer such as a multilayer wiring board, and the like. Needless to say.

〔Example〕

(I) Evaluation sample 42Alloy having a width of 2 mm, a length of 20 mm and a thickness of 0.25 mm as an evaluation sample
As shown in Table 1, on the outer surface of a metal plate made of a metal sheet having a metal layer made of an alloy of cobalt and sulfur as an underlayer (the present invention) and a metal layer of cobalt being made to intervene. 100 pieces of each were prepared.

(II) Solder peelability test The above-mentioned evaluation sample was used for molten tin 6 controlled at 245 ° C ± 5 ° C.
After immersing and soldering in eutectic solder of 0 wt% and 40 wt% lead, the same conditions as the burn-in test to check the characteristics of the semiconductor integrated circuit device, that is, 250 in an oven controlled at 150 ° C. After aging treatment for time, each sample was bent at a right angle, the number of solders that did not peel off was counted, and the solder peeling non-defective rate was calculated.

The results are shown in Table 1.

As can be seen from Table 1, in the sample No. 1 in which the sulfur-free cobalt metal layer was formed as the base of the conventional gold conductive layer, the rate of non-soldering was only 18%, and the electronic component When applied to, it becomes a big problem. If the sulfur content exceeds 1.5% by weight, the underlying metal layer is discolored due to oxidation, which is not desirable.

On the other hand, according to the present invention, in the case where the metal layer made of the alloy of cobalt and sulfur containing 0.001% by weight or more and 1.5% by weight or less of sulfur is formed, the yield rate of solder peeling can be 100%. found.

〔The invention's effect〕

As described above, according to the present invention, even if the burn-in test for checking the characteristics of the semiconductor integrated circuit element is performed by providing the metallized metal layer and the metal layer made of an alloy of cobalt and sulfur on the surface of the external lead terminal. It prevents the tin contained in the solder from diffusing into cobalt, so that even if external stress is applied, the solder does not peel off from the surface of the metallized metal layer provided on the insulating substrate or the external lead terminals. Reactivity (wettability) with the brazing material is deteriorated even when heat is applied when the circuit element is attached, or after airtight sealing after attachment, and when exposed to oxidizing conditions such as high temperature and high humidity. There is nothing to do.

[Brief description of drawings]

FIG. 1 is a partially cutaway plan view showing an electronic component of the present invention as an example of a package for housing a semiconductor element with leads,
FIG. 2 is an enlarged cross-sectional view of the main part of FIG. 1 ... Insulating substrate 2,3 ... Metallized metal layer 4,5,6 ... Cobalt-sulfur alloy metal layer 7,8,9 ... Gold conductive layer 10 ... Semiconductor integrated circuit element 11 ... Wire 12 ... External lead terminal 13 Lid

Claims (1)

[Claims] 1. In an electronic component having a gold conductive layer on a metal surface, cobalt (Co) 9 is used as a base of the gold conductive layer.
An electronic component having a gold conductive layer, characterized in that a metal layer made of an alloy of 8.5 to 99.999% by weight and sulfur (S) 0.001 to 1.5% by weight is provided.