JPS6147705B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides, as a first layer, a metal layer on a substrate, which has a vapor pressure higher than that of gold, has excellent adhesion, corrosion resistance, and heat resistance, and further has low diffusion with gold. The present invention relates to a multilayer metal vapor deposited composite characterized in that a layer of a composite having a continuous concentration gradient of the first metal and gold is provided as the second layer, and the third layer is gold. More specifically, for substrates such as films and molded products,
As the first layer, 1× at 1063℃, which is the melting point of gold.
One of germanium, silicon, silver, aluminum, and beryllium, which has a vapor pressure of 10 ^-5 Torr or higher, excellent adhesion and corrosion resistance, a melting point of 200°C or higher, and low diffusion with gold. A multilayer metal composite, characterized in that the second layer is a composite layer of metal and gold that is the first layer and has a thickness of at least 200 Å, and the third metal layer is made of gold. It is related to. Gold plating has traditionally been used in many fields for decorative and corrosion-resistant purposes. However, gold plating leads to high costs, so there is active research into alternatives such as making the gold layer thinner, but the problem is that when making the gold layer thinner, which is said to have the poorest adhesion among metals, It is difficult to use as a corrosion-resistant film due to instability of adhesion and diffusion of gold.
In addition, the substitute products bring out the original luster of gold with good reproducibility,
Moreover, no material with excellent corrosion resistance could be found, and it was necessary to thicken expensive gold for reliability. Gold can be formed by a wet method or a vapor deposition method, but the former method is used in most cases. The reason for this is that the adhesion between the gold formed by the vapor deposition method and the substrate is insufficient, so that it cannot be used for its original purpose of corrosion resistance. To compensate for this drawback, when the substrate is glass or ceramic, gold plating using the vapor deposition method uses a two-layer structure in which a base metal with good adhesion is vapor-deposited, and then gold is vapor-deposited on top of it to improve adhesion. It's summery. However, as with the wet method, the main material used as the base metal is nickel, and although it is admitted that the adhesion to the substrate is improved by several orders of magnitude compared to gold alone, on the other hand, nickel has a strong scratching effect. In this case, oxygen adsorbed and a protective film of nickel oxide was formed on the surface, making it difficult to obtain uniform adhesion with the upper layer of gold. On top of that,
When the substrate is made of plastic, there is also a problem in adhesion to the substrate. This is because the vapor pressure of nickel is less than half that of gold at 1063°C, so when evaporating nickel it is necessary to raise the temperature to higher than that of gold. This is because there is a lot of gas released from plastic, which has a negative effect on adhesion.In other words, for films or molded products where the substrate is plastic, it is desirable to have as high a vapor deposition pressure as possible for the base metal, and at least the surface layer It is necessary for adhesion to have a vapor deposition pressure higher than that of gold. On the other hand, wet gold plating, which has been widely used in the past, uses a cyan bath, etc., which causes pollution problems. Although nickel is used, it is difficult to obtain uniform adhesion to the substrate and gold. If the substrate is made of an insulating material such as plastic, it is necessary to apply a core by electroless plating, then nickel plating to improve adhesion, and then gold plating. Furthermore, if the process of each plating process is not sufficiently controlled, there is a problem that the adhesion with the substrate and each layer, the gloss of the gold plating, etc. will be greatly affected. For the reasons mentioned above, it is desirable to use the vapor deposition method for gold plating, which is less polluting than the wet method, has stable luster, and simplifies the process, but as mentioned above, gold plating with sufficient adhesion cannot be performed. There was no such thing, so it was the current situation. The present invention has been made through intensive studies to compensate for the above drawbacks, and has invented a low-cost gold-plated product that uses a vapor deposition method to prevent instability of adhesion and diffusion of gold due to thinning of gold. The present invention will be described in more detail below. In order to obtain sufficient adhesion even when the substrate is plastic, the first layer metal in the present invention has a vapor pressure as high as possible to prevent gases released from the substrate as much as possible, and also has a greater adhesion than gold. It needs to be a strong metal. Furthermore, even if a metal with excellent corrosion resistance is present on the surface, micro pinholes are unavoidable in the vapor deposition method, and over a long period of time, corrosion progresses from these parts. Therefore, the first layer metal must be chemically stable. Furthermore, when the substrate is heat-formed after vapor deposition, such as when the substrate is a film, the molding temperature is generally in the range of 100 to 200°C, so metals with a melting point of 200°C or less cannot be molded. In addition, since it is necessary to thin gold in order to reduce costs, it is necessary for the first layer metal to have little diffusion with gold. The role of the second layer is to perfect the adhesion between the first layer metal and gold. In other words, when nickel was used as a base as in the past, it was difficult to maintain uniform and strong adhesion between the nickel and gold due to the nickel oxide, but the present invention completely eliminates this drawback. It is a supplement. The second layer according to the present invention is a composite of the first layer metal and gold, and has a continuous concentration gradient of 0 to 100% gold mixing ratio, and has a continuous film thickness from the viewpoint of reliability. A thickness of 200 Å or more is required, which is the film limit. Here, as a method for forming the second layer, first, the metal and gold to be the first layer are placed in a crucible and heated. At this time, the first step is to lower the melting point of gold to below 1063°C and deposit the first layer metal, and after reaching the desired thickness, the second step is to
The temperature is raised to 1063° C. or higher and the proportion of gold is gradually increased to form a second layer of composite. Here, as the first layer metal in the crucible is consumed, a third layer of gold is formed. At this time, the film thickness ratio of each layer can be controlled by the temperature and vapor deposition time in the first stage and the temperature in the second stage, and the thickness ratio of each layer can be controlled by the amount of the first layer metal and gold filled in the crucible. The film thickness can be controlled. However, if the vapor pressure of the first layer metal is too high compared to gold,
Since it is impossible to instantaneously increase the crucible temperature from the first stage to the second stage, continuous vapor deposition is not possible and it becomes difficult to form the second layer composite.
Uniform and strong adhesion cannot be obtained. Therefore, in order to compensate for the above drawbacks, we conducted intensive studies and found that the first layer metal must have a vapor pressure difference of less than 10 ⁴ with gold, which means that the vapor pressure difference between gold and gold at 1063℃ A metal having a pressure of 1×10 ⁻¹ Torr to 1×10 ⁻⁵ Torr is desirable. Therefore, the first layer metal must be chemically stable, corrosion resistant, have a melting point of 200°C or higher to withstand heat forming, and have low diffusion so as to withstand the thinning of gold. It also needs to have better adhesion than gold. Finally, in order to maintain complete adhesion between the first layer and the gold, the second layer must be
It is necessary to form a layer of 200 Å or more, and the condition for this is that the vapor pressure at gold's melting point of 1063°C is 1 × 10 ^-1 Torr.
It is desirable to have 1×10 ^-5 Torr. The present invention was achieved by intensively studying metals that meet the above conditions. That is, only germanium, silicon, silver, aluminum, and beryllium satisfy all of the above conditions, and because each layer is formed continuously as described above, it is difficult to form a two-layer structure or Unlike the two-layer construction performed by wet plating, the adhesion between the first layer and the gold was equal to the breaking strength of the alloy. As mentioned above, when gold plating is used as a decorative or corrosion-resistant film, gold alone is very expensive and results in a film with poor adhesion, but the three-layer metal vapor deposited film using the present invention has a high adhesion. It has excellent properties, can greatly reduce the amount of gold used, and can be used for decorative purposes and as a corrosion-resistant film. The present invention will be explained in more detail with reference to Examples below. Example: A 25μ thick polyester film was used as the substrate.
Since silver was used as the layer metal, the crucible was filled with 0.7 g and 0.3 g of silver and gold, respectively. In the first step, the crucible is heated to 1000°C under a reduced pressure of 5 × 10 ^-5 Torr to deposit silver as the first layer metal, and in the second step, the crucible temperature is raised to 1400°C to deposit the second layer of gold, A silver complex was formed. Furthermore, the thickness of the film obtained by vapor depositing a third layer of only gold is 2100 mm.
The thickness of the second layer was 2400 Å, and the thickness of the third layer was 500 Å. The 5000 Å film thus obtained was subjected to a peel test using adhesive tape to examine its adhesion, and to a salt water spray test to examine its corrosion resistance. The results are shown in Table 1. No.
No. 1 shows an example according to the present invention, and No. 2 shows a comparative example in which only gold was filled in the crucible and the temperature was 5×10 ^-5 Torr.
The same thickness of 5000 Å was deposited at 1400°C under reduced pressure. As is clear from Table 1, the three-layer structure film of this example has excellent adhesion and is chemically stable, so it shows the inherent corrosion resistance of gold even in the salt water spray test. I understand. In addition, the amount of gold used to obtain the same film thickness was reduced to about 25%, resulting in a significant cost reduction. 【table】

Claims (1)

[Claims] 1. 1 selected from germanium, silicon, silver, aluminum and beryllium on a substrate.
The first layer is the seed metal, and the second layer is a composite consisting of the first layer metal and gold, and the mixing ratio of gold is 0%.
The intermediate layer has a continuous concentration gradient of 100% from Metal vapor deposited composite. 2. The metal vapor deposited composite according to claim 1, wherein the second layer of the composite has a thickness of 200 Å or more.