JPS5827996A - Manufacture of plated wire for electronic machine - Google Patents

Abstract

PURPOSE:To enhance the solderability and corrosion resistance by subjecting a metallic wire to under plating of Ni and finish plating and by annealing the plated wire to reduce the grain boundary diffusion of the component of the core wire and to prevent the diffusion of it to the plated surface. CONSTITUTION:A metallic wire (including a composite wire) 1 of copper-base metal, iron or the like as a core wire is subjected to under plating 2 of Ni and finish plating 3 of >=1 kind of metal such as Ag, Sn, Sn-Pb or Sn-Ni. Annealing is carried out after the under or finish plating. Annealing after the under plating can be carried out independently of the kind of the finish plating. When the m.p. of the metal or alloy for the finish plating is high or the metal or alloy is permitted to be melted by annealing, annealing may be carried out after the finish plating. The annealing is primarily for the Ni plated layer, yet the core wire may be annealed simultaneously. By the annealing the grain size of the Ni plated layer is increased to attain this purpose.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a plated wire for electronic devices that is plated with nickel as a base.

Conventionally, various plated wires have been used as lead wires for electronic components such as resistors, capacitors, diodes, transistors, etc., or as lead wires for wiring inside electronic devices.

These plated wires are required to have high solderability and corrosion resistance.

As the core wire of these plated wires, metal wires or composite wires such as copper, copper alloy (column, brass) wire, copper-coated steel wire, iron wire, etc. are used, and on top of that, silver, tin, tin-lead alloy, etc. In the case of direct plating, the core wire components reach the plating surface through grain boundary diffusion in the plating layer due to heating during processing, producing oxides, etc., causing defects and deteriorating solderability and corrosion resistance.

In addition to grain boundaries, pinholes, inclusions, etc. also exist in the plating layer, so this tendency is fully promoted.

Therefore, as a countermeasure to the above, the conventional plating layer is made into two layers,
It is well known that the base plating is nickel and the final plating is silver.

This base nickel plating is very effective in suppressing the above-mentioned defects, but in order for nickel plating to be effective, it depends on the core wire material, surface condition, plating conditions, etc., as well as the intended use. However, nickel plating of at least 1 micron, preferably about 2 to 3 microns, was required.

This is plated! Since nickel in the raw state has fine particles and therefore has a very large grain boundary area, grain boundary diffusion of the core metal element in the nickel plating layer is relatively easy to occur, so it is necessary to increase the thickness. This is thought to be due to the fact that

Furthermore, since nickel plating has magnetic properties, it is desirable to use as little amount as possible for lead wires used in electrical circuits, etc.

The present invention was made to solve all of the above-mentioned problems, and even if the thickness of the nickel plating layer of the plated wire, which has been subjected to two base nickel plating and two finish platings, is reduced, sufficient solderability, corrosion resistance, etc. It is an object of the present invention to provide a complete method for manufacturing a plated wire that exhibits the same performance or higher performance with the same nickel plating thickness as the conventional one.

The present invention provides a method for producing pure gold by applying base nickel plating on top of pure gold, and then pouring finish plating on top of the base nickel plating. This is a method for producing plated wire for Kameko equipment, which is characterized by subjecting it to annealing.

The plated wire manufactured according to the present invention has a structure as shown in the figure, for example. In the figure, ■ is the aforementioned metal wire (containing composite wire) that serves as the core wire, 2 is the base nickel plating on it, and 3 is the final plating on it, which is silver, tin, tin-lead alloy. It is a single-layer or multi-layer plating made of one or more metals selected from , tin-Ninokel alloy, etc.

The timing of annealing in the present invention is also limited by the type of finish plating, but it is possible to perform the annealing regardless of the type of finish plating as long as it is after the base nickel plating and before the finish plating. If the metal or alloy has a high melting point or can be melted by annealing, annealing may be performed after final plating.

The annealing in the present invention is originally annealing of nickel plating counterfeit metal, but it may also be used to anneale the core wire. Annealing increases the grain size of the base nickel plating layer, reduces grain boundary diffusion of core wire components, and provides the effect of completely preventing diffusion to the plating surface.

Note that plastic working of the nickel plating layer, such as wire drawing, before annealing the nickel plating layer impairs the above-mentioned effects of the present invention, and should be avoided.

The most suitable plating solution for base nickel plating in the present invention is a sulfamino acid bath, followed by a Watt bath and a chloride bath. This is because nickel plating from a sulfamic acid bath provides sufficient treatment under the mildest annealing conditions, and this tendency is more pronounced in sulfamic acid baths that do not contain chlorides in the load.

Regarding the annealing temperature in the present invention, the above-mentioned effect begins to appear clearly at 150°C or higher, and at 300°C or higher, the effect can be sufficiently confirmed by annealing for about a few minutes. Further, according to a method such as continuous current annealing, annealing can be performed even in a very short period of time (for example, about 10 seconds). Actually, it cannot be stated with any certainty, as it depends on the method of base nickel plating, thickness, core wire diameter, type of finishing plating, thickness, and purpose of use.

Example: A 0.5 mm/brass wire was used as the core wire, and a base nickel plating with a thickness of 0.4 microns was first applied thereon using a sulfamine nickel plating bath. Furthermore, finish plating of the type and thickness shown in Table 1 was applied thereon.

During these steps, those annealed at the annealing times and conditions shown in Table 1 and those not annealed were produced.

The plated brass wire obtained was heated to 60°C1 relative humidity (
Table 1 shows the results of measuring the solderability after conducting an accelerated deterioration test in which the samples were left for 500 hours in a room with a relative humidity of 90%.

The soldering performance was evaluated by visually observing the area wetted by the solder when a wire sample was immersed in eutectic solder at 230°C ± 5°C for 3 seconds and pulled up using inactive rosin flux. did.

6. From Table 1, it can be seen that the plated wires 1 to 3 according to the present invention had better soldering properties after the accelerated deterioration test and did not deteriorate compared to the comparative example 4 which was not annealed.

As described above, the present invention provides a method for manufacturing a plated wire that has been subjected to base nickel plating and finish plating, after the base nickel plating or after the finish plating,
Because annealing is performed at a temperature of 150°C or higher,
The grain size of the base nickel plating layer increases, reducing the grain boundary diffusion of core wire components and preventing them from diffusing to the finished plating surface, which has the effect of maintaining good soldering properties and corrosion resistance for a long period of time. In particular, for the same performance as the conventional one, the thickness of the base nickel plating can be made thinner, and even with the same base nickel plating thickness as the conventional one, there is an advantage that the performance is improved.

[Brief explanation of drawings]

1... Metal wire (core wire), 2... Base nickel plating, 3... Finish plating. ) 559-. 1 2 3

Claims (3)

[Claims] (1) In a method of manufacturing a plated wire in which a base nickel plating is applied on a metal wire and a finish plating is applied thereon, the wire is annealed at a temperature of 150°C or higher after the base nickel plating or the finish plating. A method for producing a plated wire for electronic devices, characterized by subjecting the plated wire to. (2) The method for manufacturing a plated wire for electronic equipment according to claim (1), wherein the base nickel plating has a thickness of 0.2 microns or more. (3) The final plating is a single-layer or multi-layer plating made of one or more metals selected from the group consisting of tin, tin-lead alloy, and silver. ) The method for manufacturing a plated wire for electronic devices as described in item 2.