JPS633036B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a gold-plated electronic component, and more particularly to an electronic component that is of high quality even with a thin gold-plated layer, and a method for manufacturing the same. [Prior Art and Problems] Due to its excellent physical properties, gold is widely used in gold plating of various electronic parts. Gold has good properties for bonding, brazing, soldering, etc. when used in electronic parts made of metallized ceramic, but it is extremely expensive, so it is important to keep the plating layer as thin as possible. I want to use it. Although such a demand has been strong for some time, it has not been possible to realize it. This is because when it is thinned, the plating of the underlying Ni, Cu, etc.
Or, because the metallized layer cannot be made dense, it may diffuse onto the gold-plated surface, or pass through pinholes in the Au and cause deterioration of the underlying layer, resulting in heat-resistant discoloration, peeling of silicon chips, deterioration of bonding properties, and poor lid attachment due to Au/Sn seals. This is because heat resistance and connection performance will be inferior. Therefore, we had no choice but to use a thicker plating layer, even though it increased the cost. [Means and effects for solving the problem] In view of the current situation, the inventors of the present invention have conducted intensive studies on electronic components that do not cause performance deterioration even with a thin gold plating layer, and have developed a method using a special alloy as a base for gold plating. They found that it was sufficient to apply plating and completed the present invention. In other words, the gist of the present invention is to apply cobalt 2 to 60% as a base for gold plating to the silicon chip mount portion of an IC package whose metal surface is plated with gold.
Weight%, the balance is nickel alloy plating,
The present invention relates to a gold-plated electronic component and a method for manufacturing the same, characterized in that gold plating with a thickness of 2 μm or less is applied on the plating of this alloy. The present invention will be described in detail below. The present invention relates to an electronic component having a metal surface plated with gold. There are no particular restrictions on the metal surfaces that can be applied, and metals that make up ordinary electronic components, such as copper,
It may be made of iron, aluminum, etc., and in addition to these materials, the surface of the ceramic substrate may be metallized with a material mainly composed of tungsten, molybdenum, etc., or a mixture thereof. Examples of gold-plated electronic components include silicon chip mounts in IC packages, and Au functions include wire bonding and chips for electronic components. Now, in the present invention, the silicon chip mount part of the IC package is plated with an alloy of 2 to 60% by weight of cobalt and the balance is nickel as a base for gold plating, and on top of this alloy plating, gold plating with a thickness of 2μ or less is applied. It is characterized by There are no restrictions on the method of plating the alloy, and the plating is performed to a thickness of 0.1 to 10 μm, preferably 0.5 to 5 μm, by a method such as electroplating or electroless plating. The content of cobalt in the alloy is preferably 2 to 60% (by weight, the same hereinafter), particularly preferably 7 to 40%. If it is less than 2%, heat resistance and connectivity will not improve significantly. Also
If it exceeds 55%, the solderability will be poor, and cobalt will have poor solderability when compared to nickel.
Since it is quite expensive, it is not advantageous in terms of cost. It is more preferable to treat the alloy at 700° C. or higher in a non-oxidizing atmosphere after plating the alloy, since this will result in a dense plating film and good adhesion of the plating layer to the base. In addition, the present inventors have discovered that Co/
When the Co/Ni ratio contained in the alloy plating film was investigated when the Ni ratio was varied, it was found that cobalt was preferentially precipitated over nickel, as shown in Figure 1. Therefore, in the alloy plating film,
In order to keep the Ni/Co ratio constant, it is necessary to replenish Co, and the replenishing solution contains Ni and Co, and the Ni/Co ratio is always smaller than the Ni/Co ratio in the alloy plating solution. It needs to be a ratio.
It is preferable to plate the alloy while adding such a replenisher, since a plated film of constant quality can be obtained. In addition to the liquid, Ni and Co can also be supplied from the anode. Once the alloy has been plated as described above, it is then plated with gold using a known method. The silicon chip mounting portion of an IC package in a conventional electronic component is usually gold plated to a thickness of 2 to 4 microns, although this varies depending on the application. On the other hand, in the present invention, the base material is plated with an alloy of 2 to 60% by weight of cobalt and the remainder is nickel, so the same performance can be obtained even if the thickness is reduced by 1 to 2 microns compared to the conventional method. That is, in ceramic packages for LSIs, when nickel plating is applied as the base, the gold plating is usually 3 to 4 microns thick. In contrast, in the present invention
Gold plating to a thickness of 1.5 to 2 μm is sufficient. The reason why it is possible to obtain the same performance as conventional products even if the gold plating layer is made thinner is because the base layer contains cobalt, which greatly reduces the diffusion of nickel into the gold from the base layer. This is thought to be because the purity of the gold plating layer is maintained. [Effects of the Invention] According to the invention set forth in claim 1, although the silicon chip mounting portion of the IC package is a thin gold plating layer of 2μ or less, it is possible to mount the silicon chip with Au/Si. It can be fixed securely by crystal alloy. Also, gold plating is
Because it is thin, less than 2μ, it is possible to keep costs low, making it extremely practical. Furthermore, according to the invention of claim 4,
Since the plating process is performed by adding a replenisher containing nickel and cobalt at a ratio smaller than the nickel/cobalt ratio in the plating solution to the plating solution containing nickel and cobalt, a plating film of consistent quality can be obtained. It will be done. [Examples] The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded. In other words, the alloy used as the base for gold plating is cobalt 2~
60% by weight, the balance being nickel,
It also includes those containing other elements such as Fe as long as the properties are not changed. Example 1 A metallization mainly consisting of W was printed on a green tape molded from alumina and resin, and each green tape was laminated and sintered to produce a standard side blaze type LSI ceramic package. To this, cobalt sulfate was added to the Wat bath as a base, and plating with various Ni/Co ratios listed in the table was applied to a thickness of 2μ to serve as a base for gold plating. Next, gold plating was applied to a thickness of 1.5μ using a commercially available gold plating liquid (trade name: “Tempelex 401” manufactured by Tanaka Kikinzoku Co., Ltd.), and various properties were determined.
Evaluated 10 times. (Test method) (1) Die attach test A silicon chip was bonded while scribing in N ₂ gas at 450°C. After bonding, a chip with leakage of 90% or more of the Au/Si eutectic alloy around the chip was considered to have passed. (2) Aging test The die-bonded sample was heated at 300℃ in _N2 gas.
The chips were left to stand for 0, 15, 30, 50, 75, 150, and 200 hours, and the chips were pressed with a force of 500 g to determine at what time the chips peeled off. Those that did not peel off for more than 30 hours were considered acceptable. (3) High temperature storage test After leaving the sample at i75℃ for 250 hours (in the atmosphere),
Those with no rust were considered acceptable. (Results) Among the tests (1) to (3) above, the number and occurrence time of failed products are shown in the table. As is clear from the table, the inclusion of cobalt in the nickel metal improves the performance in each test. Reference Example When a Ni/Co alloy containing 5% Fe was plated and tested in the same manner as in Example 1, almost the same results as in Example 1 were obtained.

【table】

【table】 [Brief explanation of the drawing]

Figure 1 shows the amount of Co/Ni contained in the alloy plating film when the Co/Ni ratio in the alloy plating solution was varied.
It is a graph showing changes in Co/Ni ratio.

Claims (1)

[Scope of Claims] 1. The silicon chip mount part of the IC package, which has been plated with gold on the metal surface, is plated with an alloy of 2 to 60% by weight of cobalt and the balance of nickel as a base for the gold plating. on top of
A gold-plated electronic component characterized by applying gold plating with a thickness of 2μ or less. 2. The gold-plated electronic component according to claim 1, wherein the metal surface is obtained by metallizing the surface of a ceramic substrate. 3. The gold-plated electronic component according to claim 1, wherein the alloy contains 7 to 40% by weight of cobalt and the balance is nickel. 4. When manufacturing the silicon chip mount part of an IC package with gold plating on the metal surface, a plating solution containing nickel and cobalt is used.
While adding a replenisher containing nickel and cobalt at a ratio smaller than the nickel/cobalt ratio in the plating solution, plating an alloy of 2 to 60% by weight cobalt and the balance nickel is applied to the metal surface as a base for gold plating. A manufacturing method for gold-plated electronic parts, which is characterized by: 5. The method for producing gold-plated electronic components according to claim 4, which comprises treating in a non-oxidizing atmosphere at 700° C. or higher after plating the alloy.