JPH0665703A - Hot-dip metal coating method and device therefor - Google Patents

Abstract

PURPOSE:To provide a hot-dip metal coating method by which hot dipping metal bath surface at pulling-up part of a wire material is made to be clean condition without any oxide and the other impurities and a metal coated layer having uniform thickness and flatness is obtd. over the whole surface of the wire material at the time of applying the hot-dip metal coating by dipping the wire material of copper wire, etc., into the hot dipping metal bath. CONSTITUTION:In the hot-dip metal coating method for forming the metal coated layer on the surface of the wire material by dipping the wire material (b) into the hot dipping metal bath of molten metal (a) and pulling up to out of the bath, a jetting device 3 for developing the jet by circulating the molten metal (a) in the hot dipping metal bath is provided to form the jet at the pulling-up part A of the wire material (b) from the hot dipping metal bath. Further, the pulling-up part A from the hot dipping metal bath is made to be in the non-oxidized gaseous atmosphere. By jetting, the impurities near the pulling-up part are always made flow out and by making into the non-oxidized gaseous atmosphere, the generation of the oxide film is prevented.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a resistor, a capacitor,
The present invention relates to a method and apparatus for plating filaments used as leads or terminals of various electronic parts such as diodes and sensors.

[0002]

2. Description of the Related Art As methods for plating tin or tin-lead alloy (solder) on a filament, there are roughly classified an electroplating method and a hot dipping method. Compared with electroplating, hot dip plating is
While it has advantages such as low equipment cost, easy management of plating conditions, and no waste plating solution, it has drawbacks that it is difficult to obtain a plating layer having a uniform thickness and a smooth surface.

These drawbacks include, in terms of the plating thickness, one side is thick and the other side is thin in the cross-section of the filamentous body, and the plating thickness is locally minimized in the filamentous body. There is a phenomenon such as the phenomenon that the plating thickness changes periodically in the length direction of the filamentous body like a bamboo knot. For surface smoothness, fine irregularities on the surface, uneven surface oxidation, Alternatively, there is adhesion of impurities to the surface.

As a technique proposed to overcome such drawbacks, there is an invention described in Japanese Patent Laid-Open No. 62-7840. As shown in FIG. 3, this is a device for immersing a metal filament 22 in a plating bath 21 and vertically pulling it up to perform plating. The active gas seal portion 23 is provided. By such a seal portion 13, the surface of the plating bath is prevented from being oxidized, and the influence of the oxide film which hinders the uniform plating layer is eliminated.

[0005]

As described above, if a gas seal is applied to the introduction part B and the pulling part A of the metal filament in the plating bath, a considerable improvement can be made, but oxides and impurities from the pulling part A can be improved. You can't get rid of it. The largest reason why oxides and impurities cannot be removed from the pulled-up portion A even with gas sealing is the flux applied to the metal filament 22 and brought into the plating bath. That is, the metal filament 22 is immersed in the flux solution as a pretreatment,
It is applied to the surface (not shown). The applied flux is brought into the plating bath together with the filaments to exert a flux effect, and at the same time, part of the filament surface
Another part reacts with the molten metal to form a reaction product. In addition, some others are pyrolyzed to produce decomposition products. This is because these products adhere to the surface of the filamentous body or reach the pulling up portion through the plating bath and accumulate on the surface of the plating bath in the gas seal portion to impede the uniformity of the plating layer. Further, the oxide film on the surface of the metal filament also causes contamination of the pulled-up portion, and it is practically impossible to completely prevent the oxidation of the surface of the plating bath even if gas sealing is performed.

[0006]

The present invention has been made in order to solve the above problems, and the surface of the plating bath of the linear body pulling portion is made clean without any oxides or other impurities. The present invention provides a plating method and apparatus capable of obtaining a plating layer having a uniform thickness and smoothness over the entire surface of a filament.

[0007] Its characteristic is that in the hot dip plating method of forming a plating layer on the surface of the filament by immersing the filament in a molten metal plating bath and pulling it out of the bath. Form a jet of molten metal in the pulling up part,
Moreover, this plating bath pulling up part is made into a non-oxidizing gas atmosphere. An apparatus for carrying out this method is a plating bath for storing molten metal, and a sinker roller for guiding a linear body immersed in the molten metal and pulled up, and a jet flow by circulating the molten metal. It is characterized in that it is equipped with a jet device, the nozzle of the jet device is arranged at the plating bath pull-up part of the linear body, and the pull-up part is provided with a gas seal chamber which makes a non-oxidizing gas atmosphere.

A specific example of the present invention will be described with reference to the drawings. (Plating apparatus) FIG. 1 is a schematic diagram showing the apparatus of the present invention. The plating bath 1 is provided with a heater (not shown) on the outer periphery thereof, and a molten metal a for forming a plating layer is stored inside and the temperature thereof is adjusted. To control. The plating is carried out by immersing the filament b in the molten metal and pulling it up vertically. In such a plating bath 1, the sinker roll 2 for guiding the filament 11 and the jet flow. Device 3 is provided.

The jet device 3 circulates the molten metal a to generate a jet at the pulling portion A of the filament b. For example, the molten metal intake 6 and the jet nozzle 5 and the press-fitting pump are provided in a closed container. 4, the molten metal a is taken into the jet device from the take-in port 6 and overflows from the nozzle 5 to form a jet flow. A part of the molten metal ejected as a jet from the nozzle adheres to the linear body as a plating layer, and the other part is circulated to the plating bath.
Usually, most of the impurities in the plating bath float on the surface or precipitate at the bottom, and the intake port 6 is preferably provided in the plating bath intermediate layer free of these impurities.
Further, the nozzle 5 is provided at the pulling-up portion A of the plating bath so as to surround the filament b, and its opening edge is set to be slightly higher than the surface of the plating bath. The filament b is attached to the nozzle 5
A guide die 7 is used for the introduction.

The filament pulling portion A of such a plating bath is surrounded by the gas seal chamber 8.
The gas seal chamber 8 is provided with a passage hole 9 through which the pulled-up filamentous body b passes and an introduction hole 10 to which a non-oxidizing gas is supplied, and the inside thereof can be made into a non-oxidizing gas atmosphere. Here, as the non-oxidizing gas, for example, helium, argon, nitrogen, carbon dioxide alone or 2
Mixtures of more than one species are used.

(Plating Method) In such an apparatus,
As a plating raw material, for example, a metal containing tin, lead, or a tin-lead alloy as a main component is placed in the plating bath 1, heated by a heater to melt, and maintained at a predetermined temperature. At the same time, the jet device 3 is operated to generate a jet flow, and the inside of the gas seal chamber is made a non-oxidizing gas atmosphere. Here, the flow rate of the jet flow is set to an amount sufficient to always remove impurities even if the liquid surface at the tip of the nozzle 5 does not swell and the impurities float on the liquid surface. Then, the filament is introduced into the molten metal. The filamentous body is, for example, a copper wire, the cross-sectional shape of which is circular, oval,
Various types such as various polygons can be applied.

The filamentous body introduced into the molten metal is first pulled up vertically through the sinker roller 2 and then plated through the guide die 7, the nozzle 5 and the gas seal chamber 8. Here, the filament pull-up part A of the plating bath
Since the molten metal a is jetted and overflows from the nozzle 5, the liquid surface is sequentially updated with new molten metal, and an oxide film is not formed in combination with the effect of suppressing the oxidation of the gas seal chamber 8. . Further, even if impurities float on the surface of the plating bath in the gas seal chamber, they are not washed away by the jet stream in the vicinity of the filaments and are not attached to the plating layer.

As described above, by pulling the filament from a clean plating bath free from any oxide film or impurities, a smooth liquid plating layer having a uniform thickness can be formed on the filament surface. Part of this liquid plating layer flows down due to gravity, and settles to an equilibrium thickness determined by several conditions such as the viscosity of the molten metal, temperature and cooling rate. During this time,
Since there are no oxides or impurities on the plating layer surface, the liquid plating layer flows evenly and evenly without reaching any obstacle to reach the equilibrium thickness, resulting in uniform thickness over the entire length and smooth surface. An excellent plating layer is formed.

In this embodiment, the gas seal chamber is provided only in the pulling up portion A, but a similar gas seal chamber may be provided in the plating bath introducing portion B of the filament. As a result, it is possible to prevent oxidation of the plating bath surface in the vicinity of the filament introducing portion.

[0015]

【Example】

(Example 1) The plating was actually performed using the apparatus shown in FIG. The plating conditions are as follows. Striatal: A 0.6 mmφ copper wire coated with water-soluble flux by pretreatment. Molten metal: 90% tin, 10% lead solder. Plating bath temperature: 280 ° C Linear velocity: 30 m / min Non-oxidizing gas: Nitrogen

As a comparative example, the jet apparatus was removed from the apparatus shown in FIG. 1 and plating was performed under the other conditions similar to the above. Then, with respect to these plated wires, the uniformity of the plating thickness and the smoothness of the surface were evaluated. As for the uniformity of the thickness, 50 samples were cut from the manufactured plating wire at intervals of 10 m, and the plating thickness at four places (to) was measured by fluorescent X for each sample as shown in FIG.
The thickness was measured with a line, and the average value and standard deviation of all the measured values were obtained. The smaller the standard deviation, the more uniform the plating thickness was evaluated. On the other hand, the smoothness was evaluated by a 10-point method (good 10 points) by conducting a macroscopic inspection by 3 persons with a plated wire of about 1 kg in a bundle. The results are shown in Table 1.

[0017]

[Table 1]

As shown in the table, it was confirmed that the examples were significantly improved in both plating thickness uniformity and surface smoothness as compared with the comparative examples.

(Embodiment 2) Next, the plating conditions of the above Embodiment 1 are as follows: filament: width 2 mm, thickness 0.1 mm, copper flat wire, molten metal: tin 60%, lead 40% solder. The plating was performed under the same other conditions. As a comparative example, plating is carried out by an apparatus in which the jet apparatus is removed from the apparatus shown in FIG.

The obtained plated wire was evaluated for uniformity of plating thickness and surface smoothness.
The evaluation method was the same as in Example 1, but the measurement points of the plating thickness were two points on the surface of the rectangular wire for each sample. The results are shown in Table 2.

[0021]

[Table 2]

As shown in the table, it was confirmed that even in the case of the rectangular wire, the examples are excellent in both plating thickness uniformity and surface smoothness.

[0023]

As described above, according to the method of the present invention, a jet flow is formed in the drawing bath of the filamentous body and the periphery thereof is made into a non-oxidizing gas atmosphere, so that oxides and impurities It is possible to form a uniform plating layer without being affected by. Further, the device of the present invention is optimal for carrying out the method of the present invention, and can certainly achieve the above-mentioned effects.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an outline of a device of the present invention.

FIG. 2 is an explanatory diagram showing measurement points when measuring the thickness of a plating layer.

FIG. 3 is a configuration diagram showing a conventional plating apparatus.

[Explanation of symbols]

 1 plating bath 2 sinker roll 3 jet device 4 press-fitting pump 5 nozzle 6 intake port 7 guide die 8 gas sealing chamber 9 passage hole 10 introduction hole 11 copper wire 12 plating layer 21 plating bath 22 metal wire strip 23 inert gas seal Part a Molten metal b Striatum A Lifting part B Introducing part

Claims (2)

[Claims] 1. A hot-dip plating method for forming a plating layer on the surface of a filament by immersing the filament in a molten metal plating bath and pulling it out of the bath. 1. A hot dip plating method, characterized in that a jet of molten metal is formed on the surface of the bath, and the pulled-up portion of the plating bath is in a non-oxidizing gas atmosphere. 2. A plating bath for storing molten metal, comprising a sinker roller for guiding a linear body immersed in the molten metal and pulled up, and a jet device for circulating the molten metal to generate a jet flow, A hot dip plating apparatus comprising a gas seal chamber in which a nozzle of the jet device is arranged in a drawing bath of a filamentous body, and the drawing portion is in a non-oxidizing gas atmosphere.