JPH0241591B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an Ag-coated Cu-based material (hereinafter abbreviated as Ag-coated material) that has excellent corrosion resistance and solderability, and has excellent adhesion that does not deteriorate even when exposed to high-temperature environments, and a method for producing the same. It is something. In general, Ag coating materials, which are formed by forming an Ag or Ag alloy layer on a Cu base material, have the characteristics of the base material as well as the excellent corrosion resistance and solderability characteristic of Ag, so they have been used for various purposes. . For example Cu or Cu
An alloy wire material is used as a base material, and a thickness of 0.5 to 10μ is applied to the base material.
The Ag coating material with the Ag layer formed on it is known as an economical, high-performance material that has the excellent corrosion resistance and solderability of Ag in addition to the mechanical strength of the base material.
It is widely used as a lead material for electronic components and as a conductor in electronic devices. When such Ag coating materials are subjected to heat treatment such as annealing treatment or exposed to high temperature environments in the atmosphere, such as when used in high temperature conditions, oxygen in the atmosphere actively penetrates into the Ag layer and damages the base material. Oxidize the surface and bond with the base material.
Not only does this reduce the adhesion between the Ag layers, leading to a decrease in soldering strength, which impairs the reliability of the electrical connection, but the base material also diffuses into the Ag layer, impairing the appearance of the Ag coating material, and reducing solderability. There was a drawback that the electrical contact resistance was significantly impaired. Therefore, exposed to high temperature environment
Ag-coated materials require thicker silver layers;
This is the cause of the cost increase of Ag coating materials. In such Ag coating materials, materials in which an intermediate layer made of Ni or Ni alloy is provided between the base material and the Ag layer have been put into practical use in order to prevent Cu and the like from diffusing into the Ag layer. The Ni or Ni alloy layer acts as a diffusion barrier for Cu, etc., and prevents Cu, etc. from advancing to the surface of the Ag layer.
It is said that the surface quality of the coating material does not deteriorate and is economical. However, although the Ni or Ni alloy intermediate layer prevents the diffusion of Cu, etc., it cannot prevent oxygen from entering into the Ag layer, and oxygen that has penetrated through the Ag layer may cause the surface of the Ni or Ni alloy intermediate layer to had the disadvantage of oxidizing and reducing the adhesion between the Ni-based intermediate layer and the Ag layer. In view of this, as a result of various studies, the present invention has been developed to provide corrosion resistance, solderability, adhesion, and electrical contact properties even when exposed to high-temperature environments in the atmosphere, such as annealing treatment, other heat treatments, or use in high-temperature conditions. We have developed an Ag coating material that does not damage the materials, etc., and a method for manufacturing it. That is, the Ag coating material of the present invention is an Ag coating material in which an Ag or Ag alloy layer is formed on a Cu base material.
The invention is characterized in that an intermediate layer made of Zn or a Zn alloy having a Zn content of 50% or more is provided between the base material and the Ag or Ag alloy layer. In addition, in the method for producing the Ag coating material of the present invention, in the production of the Ag coating material in which an Ag or Ag alloy layer is formed on the Cu base material, Zn or Zn content is added to the Cu base material.
It is characterized by plating 50% or more Zn alloy to a thickness of 0.01 to 3.0μ, and then plating Ag or Ag alloy. The Ag coating material of the present invention is Cu or Cu alloy or Cu
Or, the base material is copper-clad steel material coated with Cu alloy or copper-clad Al material, and Zn or Zn content is 50% on the base material.
An intermediate layer made of the above Zn alloy is provided, and an Ag or Ag alloy layer is formed on the intermediate layer.
-Alloys such as Cu, Zn-Sn, and Zn-Cd are used,
In addition to pure Ag, Ag-Cu,
Alloys such as Ag-Sb, Ag-Se, Ag-Sn, and Ag-In are used. However, the thickness of the intermediate layer is at least
The thickness is preferably 0.01μ or more and 3.0μ or less, and the thickness of the Ag or Ag alloy layer is preferably at least 0.1μ or more. As described above, the Ag coating material of the present invention uses Zn or a Zn alloy with a Zn content of 50% or more in the intermediate layer,
When exposed to high temperature environments, oxygen in the atmosphere changes to Ag or Ag.
Oxygen diffuses into the interior of the alloy layer, but is blocked by the intermediate layer of Zn or Zn alloy, and the oxidation of the Cu-based base material becomes extremely slow. Also from the middle class
Some of the Zn diffuses into both the base material and the Ag or Ag alloy layer, and the Zn diffused into the base material prevents the constituent elements of the base material from diffusing into the Ag or Ag alloy layer. Zn diffused into Ag or Ag alloy layer without impairing appearance, corrosion resistance and solderability.
Because it is uniformly dispersed within the layer and significantly reduces the diffusion of oxygen into the layer, not only the surface of the intermediate layer but also the surface of the base material and its interior are not oxidized.
There is no possibility that the adhesion of Ag or Ag alloy layer will be impaired. However, the reason for setting the thickness of the intermediate layer to 0.01 to 3.0μ is that
If it is less than 0.01μ, the above effect will not be sufficient, and if it is less than 3.0μ
Even if it exceeds this value, no greater effect can be expected, and depending on the conditions of use, excessive Zn may diffuse onto the surface of the Ag layer, impairing the appearance of the Ag, which is not desirable. In addition, the reason why the intermediate layer is made of pure Zn or a Zn alloy with a Zn content of 50% or more is because a Zn alloy with a Zn content of less than 50% cannot effectively exhibit the above effects, and even if it can, it is thick. This requires a middle class, which is uneconomical in practice. Such an Ag-coated material of the present invention is produced as follows. In other words, cladding method on Cu base material,
It can also be made by forming an intermediate layer made of Zn or Zn alloy and an Ag or Ag alloy layer thereon by the plating method, etc., but in particular, after degreasing and activating the base material by normal means, electroplated or chemically plated with Zn or Zn alloy, and then
Electroplating or chemical plating of Ag or Ag alloys is optimal. Hereinafter, the present invention will be described with reference to examples. Example 1 A pure Cu wire with a diameter of 0.6 mm is continuously supplied, and the following treatment tank is installed on the line that winds it up.
After plating, Ag with a thickness of 1.5μ was plated to produce an Ag-coated Cu wire of the present invention.

【table】

[Table] Example 2 Extending the Zn plating time in (5) in Example 1,
After plating Zn with a thickness of 0.5μ on the Cu wire, the thickness
The Ag-coated Cu wire of the present invention was manufactured by plating with 1.5 μm of Ag. Example 3 In the same manner as in Example 2, a 1.0μ thick layer was deposited on the Cu wire.
After plating with Zn, it was plated with Ag to a thickness of 1.5 μm to produce an Ag-coated Cu wire of the present invention. Example 4 In place of the Zn plating tank in (5) in Example 1,
The following Zn-Ni alloy plating tank was installed, and the thickness was set on the Cu wire.
After plating a Zn-Ni alloy (Zn content: about 70%) with a thickness of 0.1μ, a layer of Ag with a thickness of 1.5μ was plated to produce an Ag-coated Cu wire of the present invention. Zn-Ni alloy plating bath NiSO ₄・6H ₂ O 180g / ZnSO ₄・7H ₂ O 80g / H ₃ BO ₃ 30g / NH ₄ Cl 10g / Bath temperature 50% Current density 1A/dm ² Processing time 55 seconds Example 5 In Example 1, instead of the Ag plating tank (8),
The following Ag-Sb alloy plating bath is installed, and the thickness is set on the Cu wire.
After plating with 0.05μ of Zn, a 1.5μ of thick Ag-Sb alloy (Sb content: about 2%) was plated to produce an Ag-coated Cu wire of the present invention. Ag-Sb alloy plating tank AgCN 12g/ KCN 40g/ Potassium antimonyl tartrate 25g/ Potassium sodium tartrate 25g/ Current density 4A/dm ² Processing time 40 seconds Comparative example 1 Zn in the Zn plating tank (5) in Example 1
Reduces plating time and creates 0.005μ thick Zn on Cu wire.
After plating, Ag with a thickness of 1.5 μm was plated to produce an Ag-coated Cu wire of the present invention. Comparative Example 2 Zn in the Zn plating tank (5) in Example 1
After extending the plating time and plating Zn to a thickness of 4.0 μm on the Cu wire, the wire was plated with Ag to a thickness of 1.5 μm to produce an Ag-coated Cu wire of the present invention. Comparative Example 3 In place of the Zn plating tank in (5) in Example 1,
The following Zn-Cu alloy plating bath is installed, and the thickness of the Cu wire is
After plating a Zn--Cu alloy (Zn content: about 30%), that is, brass, with a thickness of 0.1μ, a layer of Ag with a thickness of 1.5μ was plated to produce an Ag-coated Cu wire of the present invention. Zn-Ni alloy plating tank CuCN 30g/ Zn(CN) ₂ 10g/ NaCN 50g/ Na ₂ CO ₃ 30g/ Bath temperature 30°C Processing time 30 seconds Comparative example 4 In place of the Zn plating tank (5) in Example 1 ,
The following treatment tank was provided, and after plating Ni to a thickness of 0.5μ on the Cu wire, Ag was plated to a thickness of 1.5μ to produce an Ag-coated Cu wire of the present invention. Ni plating tank NiSO ₂ 240g / NiCl ₂ 50g / H ₃ BO ₃ 30g / Current time 5A/dm ² Processing time 30 seconds Comparative example 5 In Example 1, the Zn plating tank (5) was omitted,
Ag coating by plating 1.5μ thick Ag directly on Cu wire
Manufactured Cu wire. Comparative Example 6 In Comparative Example 5, the plating time in (8) was doubled,
Ag coating by plating 3.0μ thick Ag directly on Cu wire
Manufactured Cu wire. These Ag-coated Cu wires were heated at a temperature of 310°C for 15 minutes in a _H2 stream, simulating the diode assembly process, and then heated at a temperature of 250°C in air for 10 hours, and after each heat treatment The solder coatings were dipped for 5 seconds in a eutectic solder bath maintained at a temperature of .degree. C., and the amount of solder adhesion was visually compared. In addition, the wires after both of the above heat treatments were twisted 80 times with a cage length of 160 mm, and the adhesion of the Ag layer was examined by comparing the peeling state of the Ag coating.
These results are shown in Table 1.

[Table] In Table 1, heating for 15 minutes at a temperature of 310℃ in _H2 air flow is
This is equivalent to soldering a Si chip, and heating in the atmosphere at a temperature of 250°C for 10 hours is equivalent to molding.It indicates the soldering and adhesion properties during and after assembly of the diode, respectively, which is clear from Table 1. As can be seen, all of the Ag-coated Cu wires of the present invention exhibit a solderability of 90% or more when soldering Si chips, and it can be seen that the solderability after diode assembly and the adhesion of the Ag film are excellent. On the other hand, Comparative Example 1 in which the thickness of the Zn intermediate layer was 0.005 μm, Comparative Example 2 in which the thickness was 4.0 μm, and Comparative Example 3 in which the Zn intermediate layer was plated with a Zn-Cu alloy with a Zn content of 30%. It can be seen that the solderability of all the coated Cu wires is deteriorated, and in particular, the adhesion of the Ag coating is significantly lowered for the Ag coated Cu wires of Comparative Examples 1 and 3. In Comparative Example 2, discoloration to yellow due to excess Zn was observed. In addition, Ag-coated Cu of Comparative Example 4 using Ni in the intermediate layer
In the wire, the Ni intermediate layer is oxidized by heating in the atmosphere,
Not only did the adhesion of the Ag film deteriorate significantly, but the solderability also deteriorated significantly, and even in Comparative Examples 5 and 6, in which Ag was directly coated on the Cu wire without using an intermediate layer, the Ag film was damaged due to oxidation of Cu. The adhesion and solderability of the
It can be seen that the Ag coating of about 3μ is still insufficient. Although the above example involves heating at a relatively high temperature, it is possible that even the Ag-coated Cu wire according to Comparative Example 2 can be practical at lower heating temperatures because Zn does not diffuse excessively to the surface of the Ag layer. As mentioned above. Further, although the above explanations have been made regarding wire rods, the present invention is not limited to this, and the same results can be obtained with plate materials, strip materials, mold materials, etc. Thus, Ag coating materials exposed to high temperatures in the atmosphere required an Ag coating with a thickness of at least 5μ, but according to the present invention, by providing an intermediate layer made of Zn or Zn alloy, Much better properties can be obtained with a thin Ag coating, which saves money.
It is also superior in terms of Ag and has remarkable industrial effects.

Claims (1)

[Claims] 1. Ag or Ag alloy layer formed on a Cu base material
In the Ag coating material, an intermediate layer made of Zn or a Zn alloy with a Zn content of 50% or more is provided between the Cu base material and the Ag or Ag alloy layer.
Cu-based material. 2. The Ag-coated Cu-based material according to claim 1, wherein the intermediate layer has a thickness of 0.01 to 3.0μ. 3 Ag or Ag alloy layer formed on Cu base material
In the production of Ag-coated materials, Zn or a Zn alloy with a Zn content of 50% or more is plated on a Cu base material to a thickness of 0.01 to 3.0μ, and then Ag or an Ag alloy is plated. A method for producing Ag-coated Cu-based materials.