JPS5952717B2 - Continuous manufacturing method for tin-plated strips - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for continuous production of tin-plated strips, and more particularly, to a method for continuous production of tin-plated strips, in which a running strip is electroplated with tin, and then the plated layer is subjected to a reflow treatment. It concerns an improvement in the method.

Nonferrous metals such as copper, copper alloys, nickel, and nickel alloys, as well as sheets and strips of steel, are plated with tin on the surface (in addition to pure silver plating, tin alloy plating containing small amounts of additive elements, etc.)
For example, tin alloys containing several percent of bismuth are added to prevent the so-called tin plague, which is a low-temperature embrittlement phenomenon of tin, and tin alloys are coated with up to 20% of lead or zinc to prevent whisker generation. This tin plating consumes approximately 50% of the total amount of tin used.

Generally, tin plating is performed by placing the material to be plated as a cathode and tin as an anode in a plating bath using silver sulfate, silver borofluoride, silver halide, silver sulfamate, silver cresol sulfonate, silver citrate, etc., and applying direct current. Tin plating is carried out by connecting a power source, and in particular, in tin plating for the purpose of corrosion resistance, after plating a thin layer of tin, the temperature is higher than the melting point of tin, e.g.
A reflow process is performed in which tin is melted by heating to 350° C. for a short period of time. This is to remove pinholes that are inevitable with thin plating, and to partially alloy the base and plating layer to improve the adhesion of the plating and to obtain specular gloss. In addition to gas burners, electric furnaces, and high-temperature oil baths, dielectric heating, electrical heating, and the like are used as heating means in large-scale production. However, this reflow treatment is severely limited when it comes to materials with high surface tension and specific gravity such as tin, and it is usually impossible to achieve uniform treatment when the plating thickness exceeds 3 μm. Furthermore, in order to avoid flow due to gravity, the plated material If it is a plate material, it is necessary to maintain its width direction horizontally.
For this reason, in continuous tin plating including reflow treatment of the strip material, the width direction of the strip material is maintained horizontally during the tin plating and the reflow treatment. That is, conventionally, as shown in FIG. 1, a strip material 1 is continuously supplied from a coil 2 wound around a horizontal shaft with its width direction being horizontal, and first, it is fed into a pretreatment tank 3.
After cleaning and activation, an anode 5, anode 5,
5', the strip material 1 is tin-plated from the bottom one side at a time, and then passed through a washing tank 6, a dryer 7, and then a heating furnace 8.
The tin-plated sheet material is manufactured by sending it to a reflow process, cooling it in a cooler 9, and winding it around a horizontal shaft 10.

In the figure, reference numeral 11 indicates power supply rolls disposed at both ends of the plating baths 4 and 4', 12 a guide roll, and 13 a pinch roll. In such a conventional method, plating tanks 4, 4
'' are arranged in two stages, upper and lower, and the width direction of each is held horizontally, and anodes 5, 5'' are placed on the lower side of the traveling strip material 1, and the strip material 1 is tin-plated from the bottom one side at a time. The reason is
This is to prevent a large amount of sludge (approximately 1% or more of the weight of the tin anode) generated from the tin anode from falling off and adhering to the strip material and causing surface defects.

However, in this conventional method, not only is the operation complicated and work efficiency is significantly hindered, but also a large amount of gas is generated from the anode and cathode because it has a greater tendency to ionize than hydrogen, and this generated gas can damage the sheet material. In addition to adhering to the lower surface, a portion of the anode sludge is suspended in the flowing plating liquid due to the generated gas, and a portion of the anode sludge is deposited on the upper surface of the strip, resulting in non-uniform plating defects.

To improve this, the method shown in Figure 2 was proposed.

This method is similar to the method shown in FIG. 1, in which the width direction of the strip material 1 is held horizontally and sent to the pretreatment tank 3, and after the surface is cleaned and activated in the tank 3, the strip material is plated in the plating tank 4. The strip material 1 is made to run in the vertical direction, and anodes 5 are placed on both sides of the strip material 1.
7 tin plating is applied to both sides at the same time, and then, as in FIG. Since it is rolled up, it is easy to operate and prevents generated gas from adhering. However, anode sludge and other particles suspended in the plating liquid adhere to the horizontal portion of the strip material 1, and this is pressed onto the surface of the strip material 1 by the guide roll 12 placed in the plating solution, causing surface defects. becomes. Also, the depth of the plating tank 5 should be at least 1. - It is difficult to replenish anodes, manage equipment, and maintain it because it needs to be at least 2 m long. Furthermore, it is difficult to select a material for the guide roll 12 placed in the plating solution that can withstand long-term use and does not damage the plating surface. In view of the above, as a result of various researches, the present invention has developed a tin-plated strip material that is not affected by the anode sludge, generated gas, etc., has good workability, is easy to manage and maintain equipment, and does not damage the plated surface. A continuous manufacturing method has been developed for tin-plated strips in which the strips are run continuously, the strips are electroplated with tin while the strips are running, and the plated tin layer is then subjected to melting treatment (reflow treatment). In manufacturing the material, the width direction of the strip material is held vertically and the strip material is tin-plated, and then the width direction of the strip material is changed from vertical to horizontal and the reflow treatment is performed. That is.

That is, in the present invention, a strip material is run, the width direction of the strip material is held vertically while the strip material is running, the width direction of the strip material is electroplated with tin, and then the width direction of the strip material is changed from vertical to horizontal. The direction is changed, and then the running plate material is held horizontally in the width direction, and the tin plating layer is reflow processed by heating it. You can use tin.

In the present invention, tin plating refers to not only ordinary tin plating, but also tin alloys containing small amounts of additive elements, such as the addition of several percent bismuth to prevent tin plague, and about 20% lead or zinc to prevent whiskers. It is also possible to perform tin alloy plating with the addition of . A specific example of the present invention shown in the drawings will be explained in more detail.

FIG. 3 is a side view showing the method of the present invention, and FIG. 4 is a plan view of the same, in which 1 is a strip material, 3 is a pretreatment tank, 4 is a plating tank, and 8 is a heating furnace for reflow treatment. The strip material 1 is continuously fed from a coil 2 wound around a vertical shaft with its width direction being vertical, and is first washed and activated in a pre-treatment tank 3, and then the strip material 1 is plated in a plating tank 4. Both sides are tinned at the same time.

In the pretreatment tank 3, degreasing with an alkaline bath and activation with an acid bath are carried out in the same manner as in the prior art, and if necessary, base plating is performed prior to tin plating, such as thin plating of indium or nickel. Between each of these steps, a washing step is performed using a conventional method. It is also preferable that the pre-treatment tank has vertical slits at the inlet and outlet of the strip material 1 so that the width direction of the strip material 1 is perpendicular to the plating tank 4 described below. The plating tank 4 has vertical slits at the inlet and outlet of the strip material 1, and is filled with tin sulfate plating solution. The plating liquid that circulates between the slits and unavoidably flows out from the slits is also collected. Further, on both sides of the strip material 1 that runs vertically in the width direction through the slit, an anode 5, which is a tin plate connected to the positive side of a DC power supply or a titanium perforated box containing a tin ball, is arranged. ing. The outside of the inlet and outlet of the plating tank 4 are made of stainless steel, for example. A pair of power supply rolls 11 having vertical shafts are provided and connected to the negative side of a DC power supply, and the rolls 11 sandwich the strip material 1 to hold the width direction of the strip material 1 perpendicularly, and at the same time Negative electricity is supplied to the strip 1. The roll 11 is driven and rotated as necessary.
It's okay. The tin-plated strip material 1 passes through a washing tank 6 and a dryer 7 as in the past, and then is sent to a heating furnace 8 where it is subjected to reflow treatment and cooled in a cooler 9, but the plating tank 4 is The discharged strip material 1 enters the heating furnace 8, where its width direction is changed from vertical to horizontal.

The figure shows a unit with a vertical rotation axis between the dryer 7 and the heating furnace 8.
A pair of rubber rolls 14 and a pair of rubber rolls 15 having a horizontal rotation axis are arranged at intervals that do not substantially cause plastic deformation of the strip material 1, and the strip material 1 is rolled by the rolls 1;4,15. Although an example is shown in which the width direction is changed from vertical to horizontal, the width direction is not limited to this. The conversion may be carried out in the tank 6 or the dryer 7, and as a conversion means, order 5
This may be carried out using a number of guide rolls that are subsequently displaced. The plate material 1, which has been subjected to reflow treatment with its width direction held horizontally in this way, is cooled in a cooler 9 and then placed on a horizontal axis 10.
It is wound up.

In the figure, 12 indicates a guide roll, and 13 indicates a pinch roll. Next, examples of the present invention will be described. Width 1
A pure copper strip coil of 50 mm and 1.0 mm thickness was attached to a vertical shaft as shown in Figures 3 and 4, pulled out at a rate of 8 m/min with pinch rolls, and the width direction of the strip was held vertically with guide rolls. While passing through the pre-treatment tank and plating tank to a thickness of 0.7
After applying μ tin plating, passing it through a washing tank and a dryer, changing the width direction of the strip from vertical to horizontal, reflowing the tin plating layer through a heating furnace, cooling it in a cooler, and then turning it horizontally. I rolled it up.

In the pre-treatment tank, degreasing with 3% caustic soda aqueous solution, washing with water,
Surface activation with a 10% aqueous sulfuric acid solution and washing with water were performed.

In addition, as a plating tank, when the withdrawal speed is 8 m/min, one tank with a length of 3 m is used, and SnSO45Og/1. ．． H
2SO4lOOg/l, cresol sulfonic acid 100g
/l of plating liquid, and placed tin plates on both sides of the running strip to serve as anodes, and between it and a power supply roll installed outside the plating tank entrance and exit, a current density of 370 A corresponding to 4.2 A/Dm2 was applied. energized. The tinned strips are washed;
After drying, in order to change the width direction of the strips from vertical to horizontal, they were passed through a rubber roll with a vertical axis and a rubber roll with a horizontal axis.

The distance between both rolls was determined experimentally, and in the case of this example, it was approximately 3 m, and the distance between both rolls was 1 m from the running line.
I let it slack. By making the strips slacker than the running line, not only can you shorten the interval at which plastic deformation does not occur, but
It becomes easier to handle various plates and strips. Strips whose width direction has been changed from vertical to horizontal are subjected to reflow treatment in which the tin plating layer is melted in a heating furnace, but it is desirable to heat and cool them in a short period of time, using a heating furnace with a length of 1.5 m. , the gaseous fuel LNG is evenly sprayed onto the strip surface using a burner and heated.
This was cooled by air cooling.

As a result, the strip runs in the plating tank with its width held vertically, so it is completely unaffected by generated gas, anode sludge, etc., and during the reflow process, the width of the strip is held horizontally. As a result, a good tin-plated copper strip was obtained.

As described above, according to the present invention, it is not only possible to manufacture tin-plated strips of good quality without being affected by generated gas, anode sludge, etc., but also the workability is good, and equipment maintenance and management are easy. This has a remarkable industrial effect.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a conventional manufacturing method, FIG. 2 is an explanatory diagram showing another conventional manufacturing method, FIGS. 3 and 4 are illustrations of a specific example of the method of the present invention, and FIG. is a side view, and FIG. 4 is a plan view. 1 is a strip material, 3 is a pretreatment tank, 4 is a plating tank, 6 is a washing tank, 7 is a dryer, 8 is a heating furnace, and 9 is a cooler.

Claims (1)

[Claims] 1. In the production of tin-plated strips, in which the strips are run continuously, the strips are electroplated with tin during the run, and the plated tin layer is subjected to melting treatment (reflow treatment). A series of tin-plated strips characterized in that the width direction of the strip is held vertically and the strip is tin-plated, and then the width direction of the strip is changed from vertical to horizontal and reflow treatment is performed. Production method.