JPH0819544B2 - Lead steel wire for electronic parts and manufacturing method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is an electronic device having a relatively inexpensive steel wire, which is an inexpensive plating method for hot dipping, and which has good solderability even after a long time has elapsed and has a uniform film thickness. The present invention relates to a lead steel wire for parts and a method for manufacturing the same.

[0002]

2. Description of the Related Art Directly applying molten solder (tin-lead alloy) plating to a copper wire is disclosed in JP-A-62-1848 and JP-A-6-1848.
Although it is known from No. 2-7840 and the like, direct application of molten tin or solder (tin-lead alloy) plating to an inexpensive steel wire is performed on the surface of the steel wire at the time of drawing or rolling finish processing. Due to the resulting scale, the steel wire and the hot-dip galvanization are very poor and difficult. Further, even if the steel wire is forcibly subjected to hot dip plating, the adhesion and solderability of the plating are low, and it cannot be used as a lead steel wire for electronic parts.

Therefore, in the lead steel wire, in order to form the molten tin or the solder plating on the steel element wire, it is necessary to first perform the base copper plating. As the base copper plating, a copper-covered steel wire (hereinafter referred to as a CP wire) is used, or a steel element wire of a corresponding dimension is copper-plated.

In order to manufacture this CP wire, the diameter is 5 to 7
mm thick steel wire is thickened by electrolytic copper plating, and then drawn to a diameter of 2.0 mm or 1.6 mm and annealed.
In addition, wire drawing is performed to the relevant dimensions such as a diameter of 0.5 mm. Also, in the case of steel strands with the corresponding dimensions of fine products, the steel strands are easily replaced by copper, so after copper strike plating in a cyan bath,
Thick copper is plated in a cyan bath.

[0005]

Generally, the production of CP wire requires a large-scale electroplating equipment, which requires equipment cost, and the immersion of the thick steel wire causes the plating solution (cyan) to be used. The amount of pumped out is large and the treatment cost for pollution prevention is high. The CP wire has a steel wire in the central portion, so if it is copper, it may be annealed at 200 to 300 ° C., and it takes about 550 ° C. to roughen the copper surface, and moreover, the scale during wire drawing is large on the surface. It remains and takes time for pretreatment.

On the other hand, in the case of a steel wire having a corresponding size of a fine product, copper plating in a two-stage cyan bath is necessary, and the pollution prevention process becomes a problem because of cyan. CP wire and thick copper plated steel wire set the price based on relatively expensive copper, so the price of the lead wire fluctuates according to the copper market price, and if the copper base rises, the price of the lead wire also increases. There is also the problem of rising.

The present invention has been proposed in order to improve the above-mentioned problems associated with the production of hot-dip lead steel wire, and the hot-dip of hot-dip plating having good solderability and solder wettability in an accelerated deterioration test and the like. The purpose is to provide lead steel wire. Another object of the present invention is to provide a method for producing a lead steel wire for electronic parts, which can easily apply tin or solder plating to a lead steel element wire by a hot dip plating method by further improving a plating pretreatment. .

[0008]

In order to achieve the above object, a lead steel wire 1 for electronic parts according to the present invention has a thickness of a steel element wire 2 of 0.1 mm by an electroplating method as shown in FIG. 5
A base tin or solder plating layer 3 having a thickness of ˜3 μm is directly formed, and then a tin or solder plating layer 4 having a thickness of 1 to 30 μm is formed by hot dipping. In the base plating layer 3, the minimum thickness effective as a base is 0.5 μm, and a plating thickness exceeding 3 μm is economically disadvantageous.

The composition of the base plating layer 3 in the electroplating method is 100 to 10% tin and 0 to 90% lead, and the composition of the tin or solder plating layer 4 in the hot dipping method is 100 to 10% tin and 0 to lead. 90%. The material of the steel wire 2 includes iron or its alloys such as carbon steel and stainless steel.

In order to manufacture the lead steel wire 1 for electronic parts, a pretreatment of the steel material 2 is necessary, and at least the steel element wire 2 is used as an anode for alkaline electrolytic degreasing cleaning and acid electrolytic cleaning. The wire is used as a cathode for alkaline electrolytic degreasing cleaning and then acid immersion cleaning. It is necessary to wash with water after each washing step. The alkaline electrolytic degreasing cleaning using the steel wire 2 as a cathode may be replaced with the alkaline electrolytic degreasing or acid electrolytic cleaning using the steel material as an anode.

In the method of the present invention, after the above pretreatment,
First, it is preferable to directly apply an underlying tin or solder plating to the surface of the steel wire 2 by an electroplating method, and generally use an alkanol sulfonic acid bath for this plating bath. The thickness of the undercoat is 0.5 to 1 μm when the hot dipping speed is relatively fast such as 40 to 50 m / min, and 20 to 30 m.
If it is as slow as / minute, it is preferable to set it to 1.5 to 3 μm.

Next, it is immersed in the hot-dip plating bath 10 (FIG. 3), and tin or solder plating is applied relatively thickly by vertical drawing as shown in FIG. The vertical drawing method in the hot dip plating method has a plating speed of about 40 to 6 as compared with the high speed horizontal drawing method.
Although as slow as 0 m / min, the uniformity of the film thickness is maintained and the plating thickness of about 15 to 20 μm is sufficiently possible, which is preferable.

In the hot-dip galvanizing bath 10, it is passed through a horizontally movable die 11 and cooled in an atmosphere of an inert gas such as nitrogen. The horizontally movable die 11 (see FIG. 4) is used to keep the film thickness uniform and to prevent the adhesion of tin or solder residue. As illustrated in FIG. 3, usually, the surface of the tin or solder plating layer 4 is smoothed by cooling in two or three stages, and the surface oxidation of the tin or solder plating layer 4 and the plating bath 10 is performed by the atmosphere of the inert gas. To prevent.

[0014]

In the method of the present invention, in the pretreatment, by the alkaline electrolytic degreasing cleaning using the steel wire 2 as an anode and the acid electrolytic cleaning,
Oils and fats are electrically stripped from the surface of the steel wire. In this step, the steel wire 2 is covered with oxygen gas and an oxide film is formed on the surface to make it non-conductive. For this reason, alkaline electrolytic degreasing cleaning is performed by using the steel wire 2 as a cathode for reduction, and the oxide film is removed by acid immersion cleaning.

In the method of the present invention, a pollution-free plating bath 10
The steel wire 2 is electroplated with tin or solder and the thickness is adjusted to 0.5-1 μm according to the hot-dip plating rate.
Alternatively, it is set to 1.5 to 3 μm. Next, the steel wire 2 is dipped in the hot-dip plating bath 10, and the thickness of the tin or solder plating is relatively thickly applied by about 15 to 20 μm while maintaining the uniformity of the thickness of the tin or solder plating.

[0016]

EXAMPLES Next, the present invention will be explained based on examples. Example 1 A lead steel strand 2 having a diameter of 0.5 mm is pretreated according to the process illustrated in FIG. The cleaning liquid and cleaning conditions in this pretreatment are as follows.

1. Alkali immersion degreasing cleaning Sodium hydroxide 15% Surfactant 10% Liquid temperature 40-50 ° C

2. Alkaline electrolytic degreasing cleaning (+) Sodium hydroxide 15-20% Surfactant 2-5% Anode lead Steel element wire 2 Cathode Iron plate

3. Acid electrolysis cleaning Hydrochloric acid 15-20% Anode lead Steel element wire 2 Cathode Iron plate

4. Alkaline electrolytic degreasing cleaning (-) Sodium hydroxide 15-20% Surfactant 2-5% Anode iron plate Cathode Lead steel element wire 2

5. Acid immersion cleaning hydrochloric acid 20-30%

The pretreated lead steel wire 2 is immersed in an electroplating bath having the following bath composition to form a base solder plating layer 3 having a thickness of 1.5 to 3 μm and containing 3% lead and 97% tin. Stannous alkanol sulfonate 350g / l Lead alkanol sulfonate 15g / l Free acid 170g / l Brightener and dispersant 60ml / l

Next, it is dipped in a hot dip plating bath 10 (FIG. 3) and longitudinally drawn to obtain a thickness 10 having 3% lead and 97% tin.
A solder plating layer 4 having a thickness of 12 μm is formed. In the hot-dip plating bath 10, the solder-plated steel wire 1 is a horizontally movable die 11
To cool through. The plated steel wire 1 smoothes the surface of the solder plating layer 4 by cooling in three stages in an atmosphere of cooling nitrogen gas, and prevents the surface oxidation of the solder plating layer 4 and the plating bath 10.

The horizontally movable die 11 is mounted on the slice bearing 12 as shown in FIG. 4, and is installed so as to move freely without being fixed, so that the film thickness of the plated steel wire 1 can be kept uniform. Avoid adhesion of solder residue. At this time, if the die is fixed, if the plated steel wire vibrates during running, a large eccentricity will occur and the uniformity of the film thickness will be impaired.

Example 2 A lead steel wire 2 pretreated in the same manner as in Example 1 is immersed in an electroplating bath having the following bath composition to form a tin plating layer 3 having a thickness of 1.5 to 3 μm. Stannous alkanol sulfonate 320 g / l Free acid 150 g / l Brightener and dispersant 50 ml / l

Thereafter, the hot dip plating bath 1 was prepared in the same manner as in Example 1.
Then, the tin-plated layer 4 having a thickness of 10 to 12 μm is formed by dipping in 0. In the hot-dip galvanizing bath 10, the tin-plated steel wire 1 is passed through a horizontal movable die 11 and then cooled.

Example 3 Lead steel element wire 2 pretreated in the same manner as in Example 1 was immersed in an electroplating bath having the following bath composition, and had a lead content of 3% and tin content of 97% and a thickness of 0.5 to 1 μm. The solder plating layer 3 is formed. Stannous alkanol sulfonate 180 g / l Lead alkanol sulfonate 10 g / l Free acid 120 g / l Brightener and dispersant 30 ml / l

Thereafter, the hot dip bath 1 was prepared in the same manner as in Example 1.
Then, the solder plating layer 4 having a thickness of 10 to 12 μm and containing 3% lead and 97% tin is formed by vertical dipping. In the hot-dip plating bath 10, the solder-plated steel wire 1 is passed through a horizontally movable die 11 and then cooled.

Example 4 Lead steel wire 2 pretreated in the same manner as in Example 1 is immersed in an electroplating bath having the following bath composition to form a tin plating layer 3 having a thickness of 0.5 to 1 μm. Stannous alkanol sulfonate 180 g / l Free acid 100 g / l Brightener and dispersant 25 ml / l

Thereafter, the hot dip bath 1 was prepared in the same manner as in Example 1.
Then, the tin-plated layer 4 having a thickness of 10 to 12 μm is formed by dipping in 0. In the hot-dip galvanizing bath 10, the tin-plated steel wire 1 is passed through a horizontal movable die 11 and then cooled.

Comparative Example The lead steel wire used in Example 1 is cleaned by alkaline immersion degreasing, alkaline electrolytic degreasing (-) and acid immersion as in the conventional case. The pre-treated lead steel wire is coated with the cream paste and then immersed in the same hot dip bath as in Example 1 to obtain an average thickness of 10-25 with 3% lead and 97% tin.
A μm solder plating layer is formed.

The solderability of the solder-plated lead steel wires obtained in Example 1 and Comparative Example is evaluated. This solderability was measured by immersing both lead steel wires in a flux of 25% by weight of rosin and 75% by weight of 1PA for 5 seconds and then immersing them in a eutectic solder bath of 62% tin and 38% lead held at a temperature of 235 ° C. The area dipped in solder for 2 seconds and wetted with solder is expressed as a percentage (%).

Table 1 below shows the normal state of the lead steel wire and the solderability after standing for 24, 48, and 72 hours in a constant temperature bath of 170 ° C. as an average value of 5 pieces each.

[0034]

[Table 1]

Also, the solderability of both lead steel wires in a constant temperature and humidity test at 85 ° C. and 85% RH is disclosed. Table 2 below shows the normal state and 25
It is an average value of 5 pieces each showing solderability after being left for 0,500 hours.

[0036]

[Table 2]

Also, 105 ° C., 100% RH, 1.2
The solderability is disclosed in a pressure cooker test of atmospheric pressure (hereinafter referred to as PCT). In Table 3 below, the normal state of the lead steel wire and the solderability after standing for 16 hours after PCT are shown by an average value of 5 wires each.

[0038]

[Table 3]

Next, the solder wettability of both lead steel wires is evaluated. This solder wettability is determined by immersing a lead steel wire with a length of 2 mm in the same flux as above for 5 seconds and then in a eutectic solder bath maintained at 235 ° C for 7 seconds, until the solder liquid surface becomes parallel. (Zero cross time) is measured with a solder graph and expressed in seconds.

Solder wettability is disclosed in the PCT. In Table 4 below, the normal state of the lead steel wire and the solder wettability after standing for 16 hours after PCT are shown as an average value of 5 pieces each.

[0041]

[Table 4]

As is clear from Tables 1 to 4, Example 1
The lead steel wire 1 of No. 1 has good solderability after the heating and constant temperature and humidity test and after the accelerated deterioration test of PCT, as compared with the lead steel wire of Comparative Example, and the solder wettability after the accelerated deterioration test of PCT. Is also excellent. Therefore, the lead steel wires 1 of Examples 1 to 4 can be stored as electronic parts and can be sufficiently used for electronic parts.

[0043]

The lead steel wire for electronic parts according to the present invention is
Even if copper undercoating, which is expensive and is less likely to cause pollution, is not applied, it has the same adhesion and solderability as before by molten tin or solder plating, and can be used for electronic parts. The lead steel wire of the present invention is an epoch-making product as an inexpensive lead steel wire in the electronic component industry because it uses an inexpensive steel material and a hot dip plating method and does not need to use expensive copper at all.

According to the method of the present invention, it is relatively easy to treat pollution that cannot be neglected, the plating facility is small, and the equipment cost and installation cost are low. Since the plating equipment in the method of the present invention can be implemented in a relatively small installation area, the lead steel wire can be provided at low cost even when the entire equipment is taken into consideration.

Further, in the method of the present invention, the oxide film is finally removed by the acid immersion cleaning in the pretreatment, and usually hydrochloric acid is used for the acid immersion cleaning to assist the initial electrodeposition of electroplating. INDUSTRIAL APPLICABILITY The method of the present invention maintains the advantages that the number of plating steps is relatively small as a whole in the production of lead steel wire subjected to molten tin or solder plating, and that the lead steel wire is less expensive than the lead copper wire or the copper-clad steel wire are doing.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view showing a lead steel wire for an electronic component according to the present invention.

FIG. 2 is a flowchart illustrating a pretreatment process of the method of the present invention.

FIG. 3 is a schematic side view showing a hot dipping apparatus in the method of the present invention.

FIG. 4 is a cross-sectional view showing an enlarged main part of FIG.

[Explanation of symbols]

 1 Lead Steel Wire for Electronic Parts 2 Steel Element Wire 3 Electric Tin or Solder Plating Layer 4 Hot Tin or Solder Plating Layer 10 Hot Dip Bath

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location C25D 7/00 G H01L 23/50 D E // C23C 28/02 H01B 5/02 A 13/00 501 E H01G 4/228

Claims (2)

[Claims] 1. The thickness of the steel wire is 0.5 to 3 by the electroplating method.
A lead steel wire for an electronic component, wherein a base tin or solder plating layer having a thickness of 1 μm is directly formed, and then a tin or solder plating layer having a thickness of 1 to 30 μm is formed by a hot dipping method. 2. A steel wire is used as an anode for alkaline electrolytic degreasing cleaning and an acid electrolytic cleaning. Further, the steel wire is used as a cathode for alkaline electrolytic degreasing cleaning, followed by acid immersion cleaning, and then electroplating. An electron that applies tin or solder plating as a base to the surface of the wire, then immerses it in a hot dip plating bath, deposits tin or solder plating relatively thickly by vertical drawing, and cools it in an atmosphere of inert gas through a horizontal movable die. Manufacturing method of lead steel wire for parts.