JPH0551721A - Production of plated wire - Google Patents

Abstract

PURPOSE:To obtain a plating in uniform thickness over the whole length and circumference of a wire by avoiding the repellent phenomenon caused when a wire of copper, iron, etc., is thickly coated hot-dipping with tin or a tin-lead alloy. CONSTITUTION:A wire copper, iron, etc., is hot-dip coated with tin or a tin-lead alloy in >=3mu thickness. In this case, the wire is primarily electroplated with nickel, cobalt or their alloy in >=0.01mu thickness over its whole length and circumference.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a tin or tin-lead alloy plated wire by hot dipping for use in lead wire terminals, connectors and the like of various electronic parts such as fixed resistors, capacitors and coils. Is.

[0002]

2. Description of the Related Art A tin or tin-lead alloy plated wire prepared by a hot dipping method is basically manufactured through the following steps.
That is, as schematically shown in FIG. 2, a copper or copper alloy element wire 1 to be a core wire is pre-treated with degreasing 2, water washing 3, pickling 4, water washing 5, etc., and the wire surface is contaminated with oils and fats. Alternatively, it is cleaned by removing metal oxides, then immersed in flux solution 6 to adhere to the surface, and subsequently immersed in hot-melted tin or tin-lead alloy hot-dip galvanizing bath 7 for wire surface. Then, the plated wire 1'is vertically pulled up from the hot dip bath 7 and cooled by spraying water or air onto the wire 1 '.

[0003]

The plated wires used for lead wires, terminals, connectors, etc. of electronic parts are soldered by the heat received during the assembly of the parts or by the change over time during the stock period after becoming the parts. The stickiness must not deteriorate. In order to prevent deterioration, it is necessary that the plating thickness of tin or a tin-lead alloy is 3 μm or more, preferably 5 μm or more. However, the disadvantage of the hot-dip plating method is uneven thickness of the plating layer, and even if the average value is 6μ, unevenness of the plating thickness such as 1μ or less occurs on a part of the wire surface. There was a problem. Several techniques have been proposed and implemented in order to solve such problems. Most of them are methods of cooling and solidifying by using a liquid or gas immediately after the wire is drawn from the molten metal, that is, before the plating layer flows and the uneven thickness phenomenon occurs. For example, in Japanese Patent Laid-Open No. 62-1848,
Immediately after the wire is drawn out, water is sprayed to cool it. Further, Japanese Patent Application Laid-Open No. 62-7840 discloses a proposal to prevent the vibration of the wire or the vibration of the molten metal surface at the portion where the wire is pulled up to suppress the fluctuation of the plating thickness.

[0004]

[Problems to be Solved by the Invention] Although each of the conventionally proposed techniques has advantages and disadvantages, in many cases, the improvement effect is exhibited. However, the effect is unstable and still needs improvement. The inventors of the present invention have found a mechanism for making the plating thickness non-uniform, which is different from the conventionally conceived mechanism, and have realized an extremely effective method for producing a plated wire based on this mechanism.

As a method for this, first, nickel, cobalt or an alloy containing them as a main component is plated on the surface of the wire as an underlying plating. From this, it was found that the non-uniformity of the plating thickness of the tin or tin-lead alloy plated wire by the hot dip coating method is significantly improved.

It is generally already known to apply nickel plating to a base when plating tin or a tin-lead alloy by a hot dipping method. JP-A-57-35674 discloses that when a tin-lead alloy is plated on a steel sheet by a hot dip plating method, nickel, cobalt or an alloy thereof is plated by electroplating as a base plating. .. However, the technique disclosed in this publication is directed to the purpose described below. (1) The wettability (familiarity) between the base steel sheet and the tin-lead alloy is improved, and as a result, the plating rate can be improved, and the non-plated portion and pinholes are eliminated to improve the quality. (2) A tin-nickel or tin-cobalt alloy plating layer having excellent corrosion resistance is formed.

On the other hand, the purpose of the undercoat plating in the present invention is to form a tin-nickel or tin-cobalt alloy plating layer on the wire, and deposit a tin or tin-lead alloy plating layer on the wire. The purpose is to avoid the "repellent" phenomenon that occurs during the solidification of the metal and to obtain a plating layer with a uniform thickness. The present inventors have found that when the thickness of tin or tin-lead alloy plating is 3 μm or more, preferably 6 μm or more,
It has also been found that undercoating is required, and when the plating thickness is thin, the "repelling" phenomenon does not practically occur unless special conditions such as raising the plating temperature more than necessary.
Thus, according to the present invention, copper, copper alloy, iron, iron alloy,
The plating thickness of tin or tin-lead alloy is obtained by taking the step of forming a tin-nickel or tin-cobalt alloy plating layer on the wire of steel, nickel alloy, or a composite metal whose surface is the above metal. Non-uniformity is improved.

[0008]

【Example】

(Plating Step and Plating Conditions) FIG. 1 is a schematic view showing the steps for producing a tin or tin-lead alloy plated wire by the hot dipping method of the present invention. The wire 1 made of copper, copper alloy or the like is pretreated to remove dirt such as oils and fats and metal oxides from the wire surface to clean the wire 1, and then the underlying plating 8 is applied. For the Ni plating of the base, a Watt bath having a standard composition containing 63 g / l of metallic Ni was used, and the bath temperature was 50 ° C., the pH was 3.0 to 4.0, and the current density was ^{2 to} 10 A / dm ^2.
It was carried out in. For the Co plating, a plating bath having a composition in which Ni was replaced with Co in the Watt bath having the standard composition was used, and the temperature, pH, and current density were the same as those in the Ni plating. Ni-
For Co alloy plating, the above Ni and Co plating solutions were mixed at a ratio of 1: 1 and the temperature, pH and current density were the same as those of the above Ni plating bath. After the undercoating was applied, the wire was dipped in a commercially available non-chlorine-based flux solution 6, and then the wire was passed through a hot dip bath 7 and pulled out vertically. The temperature of the molten metal is 290 ° C,
The periphery of the outlet where the wire is drawn out of the molten metal is kept in a nitrogen gas atmosphere by the cover 10, and after passing through nitrogen, the plated wire 1'is cooled by cooling air, and the plating layer is solidified.
The plating line speed was 30 m / min or 40 m / min. (Measurement of plating thickness) An average plating thickness was obtained by measuring four points on the same cross section with fluorescent X-rays and averaging them. (Measurement of "repellency" phenomenon) 100mm of the plated wire is immersed in 35% fluorinated aqueous acid solution, and the wire is used as an anode to electrolyze and remove 2μ of the plating layer to determine whether the substrate is exposed. After investigation, if there was exposure, it was determined that there was a "repellent" phenomenon. (Example 1) An annealed copper wire having a diameter of 0.6 mm was run at 30 m / min according to the above process and conditions, electroplated with nickel having a thickness of 0.1 µ, and an alloy of 90% tin and 10% lead was plated thereon. did. In addition, as a comparative material, a plated wire was prepared in which the elemental wire and the plating conditions were the same and no undercoating was applied. Table 1 shows the results of measuring and investigating the plating thickness and the presence or absence of repellency phenomenon for both. As shown in Table 1, the ground effect of the present invention was confirmed.

[0009]

[Table 1]

(Embodiment 2) A brass square wire having a square cross section with a side of 0.54 mm was obtained by the above-mentioned steps and conditions.
0.7 μ of nickel was underplated, and tin was hot-plated thereon. In addition, as a comparative material, a plated wire in which the undercoating was omitted under the same material and under the same plating condition was prepared, and the plating thickness and the presence or absence of the "repellent" phenomenon were measured and investigated for both. However, the edge part of the square line was removed from the survey target of "Hajiki". The results are also shown in Table 1. (Example 3) A diameter of 0.5 mm was obtained according to the above process and conditions.
The soft iron wire with a carbon content of 0.01% was plated with 0.05 μm of nickel, and an alloy of 60% tin and 40% lead was plated on it.
The plating line speed at this time was 40 m / min. Table 1 also shows, as a comparative material, a plated wire having no undercoat under the same material and plating conditions was prepared, and the thickness of the plated wire and the presence or absence of the "repellent" phenomenon were measured and investigated.

As described above, according to the present invention, when a tin or tin-lead alloy plated wire having a relatively large plating thickness of 3 μm or more is manufactured by the hot dipping method, nickel, cobalt, or the like is used as the base of the element wire. When the alloy containing the main component is plated, there is an effect that a tin or tin-lead alloy plated wire having a uniform thickness is obtained over the entire length and the entire circumference of the wire. An example will be described with reference to FIG. The figure shows a tin-lead alloy (solder) -plated copper wire without conventional undercoating.
Indicates a copper wire and 12 indicates a solder layer. Its diameter is 0.6 mm and the average plating thickness is 8 μ. If the plating is performed as it is without nickel or cobalt undercoating, spot-like stripes will occur at the plating thickness of 1μ or less, as shown by 13 in the figure, but by applying the above-mentioned undercoating, this thin portion is eliminated. As a result, the plating thickness becomes uniform and uniform.

The above shows the one in which the present invention is carried out in addition to using copper, brass, and iron as the wire, but steel, nickel alloy, or copper, copper alloy, iron, iron alloy, steel, nickel alloy on the surface. It can also be applied to composite strands that have been subjected to, and the cross section of the strand can be applied to circles, quadrangles, as well as ellipses and polygons.

The plated wire is used as a lead wire for various electronic parts, but it may be heated in a processing step after the electronic part is incorporated into the electronic part until the electronic part is completed. It may be treated with a type of chemical that is only slightly affected. Although affected by such heat and chemicals, the lead wire must have excellent solderability when completed as an electronic component. Furthermore, the solderability must be maintained even after being left as an electronic component for 1 to 2 years. For that purpose, the plating thickness of 3 μ or more, preferably 6 μ or more is required as described above, and 1 μ or less is a fatal defect even if it is partial. By applying base plating with nickel, cobalt, etc., the generation of thin plating parts is eliminated,
The plating thickness can be uniform and uniform.

[0014]

As described above, according to the present invention, by performing underplating with nickel, cobalt or an alloy containing them, tin having a uniform thickness over the entire length or the entire circumference of the wire, or tin- A lead alloy plated wire can be obtained.

[Brief description of drawings]

FIG. 1 shows a model diagram of a manufacturing process of the present invention.

FIG. 2 shows a schematic diagram of a conventional plated wire manufacturing process.

FIG. 3 shows a tin-lead alloy-plated copper element wire that has been hot-dipped without conventional undercoating.

[Explanation of symbols]

 1 strand 2 degreasing 3,5,9 washing with water 4 pickling 6 flux solution 7 hot-dip plating layer 8 base plating 10 cover

Claims (4)

[Claims] 1. A method for producing a tin or tin-lead alloy plated wire having a plating thickness of 3 μm or more by a hot dipping method, wherein the wire surface is plated with nickel, cobalt or an alloy containing them as a main component. And a method for manufacturing a plated wire. 2. An element wire to be plated is copper, a copper alloy, iron, an iron alloy, steel, a nickel alloy, or a composite metal wire having a wire surface made of the above metal. Method for manufacturing plated wire. 3. The method of manufacturing a plated wire according to claim 1, wherein the cross-sectional shape of the element wire to be plated is a circle, an ellipse, or a polygon. 4. The method for producing a plated wire according to claim 1, wherein the thickness of the undercoating made of nickel, cobalt, or an alloy containing them as a main component is 0.01 μm or more.