JPS59180908A - Silver-coated conductor and method of producing same - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a silver-coated conductor and a method for manufacturing the same, and in particular provides an economical silver-coated conductor that has excellent heat resistance and durability.

Generally, A(] or AQ is applied on a substrate made of Cu, Fe, A, e or alloys thereof, ceramics, plastics, etc.
A conductor coated with an alloy has the characteristics of the substrate and ΔQ or A (1
Due to the alloy's excellent electrical conductivity, corrosion resistance, and solderability, it is widely used in electrical and electronic devices and their parts, such as connectors, terminals, lead frames, wires, contact springs, and cables. However, Ag
Since AC+ or A(I alloy) is an expensive noble metal, it is desired to make the coating thickness of AC+ or A(I alloy as thin as possible).

On the other hand, ``Ag easily diffuses with the substrate or its component elements, and depending on the long-term use or high-temperature environment, especially the thermal conditions and atmospheric oxidation conditions in the conductor manufacturing process, the A() or AQ alloy layer (hereinafter abbreviated as Ag layer) ), and base metal components accumulate on the surface of the AQ layer, causing oxidation and deteriorating corrosion resistance and soldering properties.For example, Cu, brass, bronze, etc., which are often used as substrates, undergo a diffusion reaction with A(1). Easy<Ag is consumed, Ag
Accumulation and oxidation of base metal components on the surface deteriorates electrical contact resistance and solderability. In order to prevent this, conventionally the base and A
A Ni intermediate layer is provided between the G layers.

Although N1 is insoluble in Aq and effectively suppresses the diffusion reaction between 80 and the substrate, at high temperatures of 200°C or higher, the surface of A (J) is oxidized by oxygen passing through the first layer, and in severe cases Peeling of the Ag layer occurs.Also, even if there is no abnormality in appearance, it becomes a serious defect in solderability. number μ
If the oxidized N1 surface is exposed and comes into contact with the solder bath, the wettability with the solder will be inhibited and the solderability will be significantly reduced. Also low)
Even in the case of crystals, the N1 surface is oxidized by oxygen passing through pinholes and scratches that inevitably exist in the thin Ag layer, and the soldering uniformity and contact resistance deteriorate. In this way, Ni is added between the substrate and the Ag layer.
Even if an intermediate layer was installed, there was a limit to how much AQ could be saved (thinned).

In view of this, as a result of various studies, the present invention improves the heat resistance and durability of a silver-coated conductor by interposing two phases of Ni, Co or an alloy layer thereof and a Pd or Pd alloy layer between the substrate and the A() layer. This was done after discovering that it can improve sexual performance.

That is, the present invention provides a conductor in which a substrate is coated with Ag or an Ag alloy, in which a layer of Ni, Co, or an alloy thereof is provided on the substrate, a layer of Pd or a Pd alloy is formed thereon, and a layer of Ni, Co, or an alloy thereof is formed on the substrate; (+ or A() alloy).

Further, the present invention is characterized in that Ni, Co, or an alloy thereof is electroplated on a substrate, Pd or a Pd alloy is electroplated on the substrate, and then Ag or an Ag alloy is electroplated thereon. A method of manufacturing a silver-coated conductor is provided.

In the present invention, the substrate includes Cu, Fe, and A, which are usually used in electrical and electronic equipment and their parts, such as connectors, terminals, lead frames, lead wires, contact springs, and cables.
J! Alternatively, by using alloys of these, ceramics, plastics, etc., a layer of Ni, Co, or an alloy thereof is provided on the substrate, a layer of Pd or a Pd alloy is formed thereon, and a layer of A is formed on the substrate.
This coats the g layer.

Ni as Ni, co or an alloy thereof.

Ni-Co, Ni-Fe, Ni besides CO
-7n.

Mechanical from alloys such as Ni-Co-Fe and Ni-P.

It is selected from the viewpoint of thermal and electromagnetic properties and diffusion prevention between the substrate and the Ag layer, and a thickness of about 0.1 to 10 μm is sufficient. Examples of Pd or Pd alloys include Pd-AQ, Pd-Ni, Pd-Go in addition to pd.
An alloy containing 50% or more of Pd, such as Pd-AU, is used.

Pd and Pd alloys are relatively inexpensive metals of the platinum group, and their specific gravity is particularly low compared to other noble metals, making them economically advantageous when used in layers, and they have excellent corrosion and oxidation resistance. There is. Therefore, Ni in high-temperature environments and long-term use
, Go, or an alloy thereof, and suppresses the occurrence of defects caused by the oxidation. In addition, Pd is an element that has an affinity with Ag and N1, and Pd1 increases due to long-term use or high-temperature environments.
It forms a three-degree boundary layer and acts effectively. However, P
The effect of d depends on the conditions of use, but it is practical to set the thickness of the pci or Pd alloy layer to 0.01 to 3μ, and 0.01 to 3μ.
If the thickness is less than 0.01μ, the effect cannot be effectively exhibited, and if the thickness exceeds 3μ, the usual great effect cannot be expected and it is not economical.

As A(j or Ag alloy, for example, in addition to A(), Ag-
CU,'A(]-Ir,A(+-8r,A(+
- Using an alloy such as sb, it is coated to a desired thickness depending on the application. Although the thickness of Ag varies depending on the conditions of use, it is usually about 1 to 10 μm, and compared to conventional silver-coated conductors, the use of much less Ag can significantly improve the reliability of electrical and electronic devices and their parts. It is something that can be done.

The silver-coated conductor of the present invention has the above-mentioned structure, and has Ni on the base.
, co or an alloy layer thereof, a Pd or Pd alloy layer thereon, and an A(l or Ag alloy layer thereon) are formed by a mechanical cladding method or an electroplating method.

It can be manufactured by an electroless plating method, a vacuum evaporation method, or a combination thereof. However, as in the present invention, a layer of l'Ji, co or an alloy thereof is formed on a substrate, and a layer of P is formed on the substrate.
Electroplating is the simplest way to produce a multilayer coating consisting of a D or Pd alloy layer and an Ag or AI alloy layer thereon. That is, after the substrate is activated by conventional means, Ni; Go or an alloy thereof is plated on the substrate using a well-known Ni, Co, or alloy plating bath. Next, electroplating is performed in a plating bath containing PD to plate PD or a PD alloy on the Ni, CO or alloy plating layer. This is A
Electroplating is performed in a plating bath containing q, and Ag or 〇 alloy is plated on the Pd or pd alloy plating layer.

As the Pd plating bath, a bath containing palladium chloride as a main component, a bath containing Pd--P salt as a main component, a sulfamic acid bath, a bromide bath, etc. are used. As the Pd' alloy plating bath, a pal-Ni organic amine salt bath or a Pd-Ag iodide bath is used. In addition, cyan bath is the mainstream as the A() plating bath, but thiocyanate bath and birophosphate bath are also used depending on the purpose.In particular, Ag-3b alloy plating can be easily obtained from cyan bath, and A!ll- 3n alloy plating, A
! A pyrophosphoric acid bath is often desirable for II-Cu alloy plating.

Hereinafter, the present invention will be explained in detail with reference to examples.

Example (1) A lead wire for a diode was manufactured by AQ plating a Cu wire having a diameter of 0.6 mm. This lead wire was treated for 30 minutes at a temperature of 350°C in hydrogen gas to solder the 3i chip, and was treated at a temperature of 230°C in the air for 20 hours to cure the sealing resin. Even after these heat treatments, the lead wire can still be used. For soldering, the Cu wire, which requires good soldering properties, is electrolytically degreased using a conventional method, then pickled, and then soldered with 0.2μ thick N wire using the following bath.
i - 10% GO alloy plating and 0 thickness
．． After 2μ Pd-20%N1 alloy plating, A
A with a thickness of 1.5μ after restriking plating (]
A diode lead wire was manufactured by plating.

Ni-10%CO alloy plating Ni SO4240 (+/J2 NiCfflz 30g/fCO80415
g/(N3BO330(]]/, eP+-1 3.2 Bath temperature
60°C current density 3.5
A/c1m2pd-20%l'Ji alloy plating PNP-80 p (120q, l! Ni1'2 (1/in pH 7,9 bath) crystal 30°C current density IA/dm2 A (]Strike plating AgCN 34 fl/, f!KCN
40q/criminal bath temperature 20°C current density
5A/dll12A(] plated ACICN 50(+/buKCN
50Q/J2 Kz CO3' 20 (J/ρ bath temperature
30°C current density 1
．． 8A/dm2 Example (2) In Example (1), PD plating with a thickness of 0.08 μm was performed using the following bath instead of Pd-Ni alloy plating.

Pd plating Pd (as P salt) 10q/! NH4S
O2(Nl-12)z 100! J/BuP H
7,5 Bath temperature
32°C current density 0.5A/
dm2 Example (3) In Example (1), instead of l'Ji-00 alloy plating, N plating with a thickness of 0.5 μm was performed using the following bath.

N1 plating Ni SO4270Q/I Ni Cj! z 30 (]/IH3
BO330Q/p P H3,0 Bath temperature 45°C Current density
2.5A, / (11112 Comparative Example (1) In Example (1), the Pd-Ni alloy plating was omitted, and 〇 strike plating was applied directly on the N1-Co alloy plating, and then the thickness was 1.5A. 5μ Ag plating was performed.

Comparative Example (2) In Example (3), the Pd-Ni alloy plating was omitted, and A(] strike plating was applied directly on the Ni plating, followed by A() plating with a thickness of 1.5 μm.

For each diode lead wire manufactured in this way, the soldering of the Si chip and the same heat treatment as the sealing resin curing were performed, and then temperature 2 was applied based on the M1L method.
They were dipped in a eutectic solder bath at 35° C. for 5 seconds, and the solder wetting areas were compared. The results are shown in Table 1.

Table 1 Lead wire Solder wettability (%) Example ('1) 92 /' (2) 9G II (3) 93 Comparative example (1) <20! 2) <20 As is clear from Table 1, the lead wires according to the embodiments of the present invention exhibit a solder wettability of 94% or more even after heat treatment, whereas the lead wires in which Pd-Ni alloy plating was omitted Ni plating, Ni
Comparative example (1) in which Ag scratch-plated directly on Co alloy plating
) and (2) both have solder wettability of 20%.
It turns out that the following is true.

In Comparative Example (2), the Ag plating thickness was 2.5μ,
When the thickness was set to 3.5μ, 4.5μ, and 5.5μ, the solder wettability was 35%, 50%, 80%, and 94%, respectively. That is, it can be seen that the heat resistance of the A(] plating is greatly improved by the pd-4Ji alloy plating with a thickness of 0.2μ and the Pd plating with a thickness of 0.08μ according to the present invention.

Example 4) A spring contact material was manufactured by plating A () on a phosphor bronze strip with a thickness of 0.32 mm.The phosphor bronze strip was electrolytically degreased and pickled using a conventional method, and then thickened using the following bath. 0.1μ C
O plating was performed, and then Pd plating with a thickness of 0.05μ was performed on it, followed by A(] strike plating in the same manner as in Example (1), and then Ag plating with a thickness of 0.5μ was performed on it. Manufactured spring contact materials.

CO plating Co S 04 400! II/BuNaCff
1 20g/f H3BO350q7.・'Soft P H5,0 Bath temperature 30°C Current density 4A/dm2 Pd plating Pd (Nl-13>z C,ez 20 (]
-Pd/12NH+CJ! 100/f
NH40H15 (1/f PH8 bath temperature 25°C current density 0.5A/dm2 Comparative example (3) In Example (4), Pd plating was omitted and A(]1 helical plating was applied directly on the CO plating, and then A spring contact material was manufactured by performing A(+ plating) with a thickness of 0.5μ.

For both contact materials, 2000 hours at a temperature of 120°C.

Each item was aged for 1000 hours at a temperature of 60°C and a humidity of 95%, with a load of 80g and r current of 0.
．． Contact resistance was measured at 1 A. The results are shown in Table 2.

Table 2 Spring contact materials Contact resistance (mΩ) age
120℃ x 60℃, 95% x 2000h before heating
r 1000hr Example (4) 3.5
4.9 5.5 Comparative example (3) 3.5
10,2 19.0 As is clear from Table 2, the deterioration of contact resistance is extremely small in the embodiments of the present invention, whereas the deterioration in contact resistance is significant in the comparative example in which Pd plating is omitted. I understand that.

In this way, the silver conductor of the present invention has excellent heat resistance and durability.
It is an economical method that improves and maintains the integrity of the layer, prevents deterioration of electrical contact and connectivity (soldering properties), and allows thinning of the Ag layer, which has a significant industrial effect. It is something to play.

Claims (3)

[Claims] (1) In a conductor coated with Δ(j or Ag alloy), a Ni, Co or these alloy layer is formed on the substrate, a PCI or Pd alloy layer is formed on it, and A
g or A! ]A silver-coated conductor characterized by being coated with an alloy. (2) The silver-coated conductor according to claim 1, wherein the Pd or Pd alloy layer has a thickness of 0.01 to 3 μm. (3) Silver characterized by electroplating Ni, Co or an alloy thereof on a substrate, electroplating Pd or a Pd alloy thereon, and then electroplating 80 or an Ag alloy thereon. Method for manufacturing coated conductor.