JPS606A - Lead wire for electronic part 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 lead wire for electronic components and a method for manufacturing the same, and more particularly to a lead wire for electronic components having a copper or copper alloy plating layer between two layers of tin or tin-lead alloy plating. This invention relates to a lead wire and a method for manufacturing the same.

Conventionally, lead wires for electronic parts have been manufactured by applying one or two layers of tin or tin-lead alloy plating by electroplating, or by applying one layer of tin or tin-lead alloy plating by hot-dip plating. Each had the following drawbacks.

That is, when it comes to electroplating, bright electroplating is brittle and cracks occur during self-diameter winding, etc., so it cannot be used, so only plating with a rough appearance can be obtained. Therefore, felt polishing or die polishing is necessary, but felt polishing has the disadvantage that polishing powder from the plated metal re-adheres, and die polishing has the problem of increased costs due to the cost of die management. In addition, the roughness of the appearance,
In particular, due to insufficient smoothness in felt polishing, chucks, conveyors, dies, etc. in the resistor assembly process tend to be prone to adhering to, clogging, or discoloring. In addition, electroplating produces pinholes, so if the metal wire is iron, steel tends to come out.

On the other hand, with hot-dip plating, the thickness is uneven and there are thin areas in the plating, so the soldering properties deteriorate significantly due to heating, humidification, etc.

The present inventors have created two tin or tin-lead alloy plating layers on the outer periphery of the metal wire, interposed copper or copper alloy fat in between, and further reflowed the metal wire, thereby achieving the above-mentioned conventional method. We have discovered that it is possible to manufacture an excellent lead wire for electronic components that solves the technical drawbacks, and have completed the present invention.

That is, the gist of the present invention is to have a first layer made of tin or a tin-lead alloy, a second layer made of copper or a copper alloy, and a third layer made of tin or a tin-lead alloy on the outer periphery of the metal wire. A first layer is formed by electroplating tin or a tin-lead alloy on the outer periphery of the lead wire and metal wire, and copper or A second layer is formed by plating a copper alloy, and then a second layer is formed.
The present invention relates to a method of manufacturing a lead wire for an electronic component, which comprises secondly electroplating tin or a tin-lead alloy to form a third layer, and then performing a reflow treatment.

In the present invention, a metal wire and a copper and copper alloy wire,
Examples include copper-coated steel wire, iron wire, and steel wire.

Although the wire diameter is not particularly limited, a typical diameter for lead wires for electronic components is 0.4 to 0°8φ.

The composition of lead or tin-lead alloy is not particularly limited, and those having a tin:lead ratio of 100:O to 20:80 are generally used. Plating is usually performed by electroplating, and the plating thickness is not particularly limited for the first layer, and is, for example, 4 to 13 μm, and usually 1 to 5 μm for the third layer.

The second layer, that is, the intermediate layer of copper or copper alloy plating, is also formed by electroplating, and its thickness is usually 0.05-0.
It is 5μ. As the copper alloy, a copper-tin alloy and a copper-zinc alloy are preferably used.

Before plating the first layer, a base plating such as nickel or copper may be formed on the metal wire.

Reflow may be performed in a conventional manner, such as by continuously feeding a plated metal wire while applying current or high frequency heating to melt the tin or tin-lead alloy, followed by water cooling.

Since the lead wire of the present invention has a copper or copper alloy layer between the tin or tin-lead alloy plating layers, uneven thickness and unevenness in the longitudinal direction do not occur even during reflow. Therefore, uniform plating thickness is obtained, surface gloss is good, and it is difficult to discolor.
It's hard to get any dregs out. Also, since the copper or copper alloy intermediate layer is thin,
Solderability is not inferior to that without the intermediate layer. Furthermore, since it is electroplated, there is the advantage that the plating thickness can be selected arbitrarily.

Next, examples and comparative examples will be shown to specifically explain the present invention.

Examples 1 to 8 and Comparative Examples 1 to 5 A 0.58φ annealed copper wire was subjected to normal alkaline electrolytic degreasing and pickling, then plated with tin or tin-lead alloy in a borofluoride bath, and then plated in a sulfuric acid bath. Copper was plated in a borofluoride bath, and then tin or a tin-lead alloy was plated in a borofluoride bath. Next, the plated copper wire was washed with water, dried, coated with rosin flux, and subjected to reflow treatment. In reflow, power is supplied to a copper wire passed between a pair of power supply rolls, the tin or tin-lead alloy plating layer is melted by resistance heating, and then drawn into a water tank installed directly below the lower power supply roll, and then melted. The tightening layer was solidified.

In addition, for comparison, the reflow treatment was also performed in the cases where thick steel intermediate plating was applied (Comparative Examples 1 to 2) and the cases where steel intermediate plating was not applied (Comparative Examples 3 to 5), except for Comparative Example 5. I did it.

Each property of the lead wire was measured or evaluated as follows.

The plating thickness distribution of a cross section with a thickness unevenness rate of 1 was measured using a cross-sectional microscope, and calculated as the maximum plating thickness - the minimum plating thickness.

Store the copper wires 5~ that have undergone colorfast reflow treatment in a paper container and heat them in a constant temperature and humidity chamber at 60°C x 90% x 12 hours + 40°C x 60%.
After 15 cycles of 12 hours, the appearance was observed.

The reflow-treated copper wire was heated at 180° C. for 4 hours, rosin flux was applied to the copper wire, and the 90° wetting time was measured using Solder Graph (trademark, manufactured by Yizai Seisakusho).

Using a scum-generating resistor cap welding machine, we measured the time until the welding machine automatically stopped due to the generation of solder scum in the chuck, and used this as a measure of scum generation.

The results are shown in Table 1.

Examples 9 to 12 and Comparative Examples 6 to 9 A 0.5φ iron wire was subjected to plating and reflow treatment in the same manner as in Example 1.

The treated iron wire was subjected to salt spray test (JISZ 23
71) for 72 hours.

The results are shown in Table 2.

Table 2 23

Claims (1)

[Claims] 1. A metal wire having a first layer made of tin or a tin-lead alloy, a second layer made of copper or a copper alloy, and a third layer made of tin or a tin-lead alloy on the outer periphery of the metal wire. A lead wire for electronic components, which is characterized by being made of aluminum and subjected to reflow treatment. 2. The lead wire for electronic components according to claim 1, wherein the metal wire is a copper or copper alloy wire, a copper-coated steel wire, a steel wire, or an iron wire. 3. The lead wire for electronic components according to claim 1, wherein the first layer has a thickness of 3 to 15 μm. 4. The lead wire for electronic components according to claim 1, wherein the second layer has a thickness of 0.05 to 0.5 μm. 5. The lead wire for electronic components according to claim 1, wherein the third layer has a thickness of 0.5 to 2 μm. 6. Electroplating tin or a tin-lead alloy on the outer periphery of the metal wire to form a first layer, plating copper or a copper alloy on the first layer to form a second layer, and further forming a second layer. A method for manufacturing a lead wire for electronic components, comprising forming a third layer by electroplating tin or a tin-lead alloy on the layer, and then performing a reflow treatment.