Environmentally friendly surface treated steel sheet for electronic parts excellent in soldering wettability and resistance to rusting and formation of whisker

A technology for surface treatment of steel plates and environmental adaptation. It is used in thin material processing, welding/cutting media/materials, welding media, etc., which can solve the problems of inability to be practical, hinder solderability, etc., and achieve the effect of excellent solder wettability.

Inactive Publication Date: 2004-04-28
NIPPON STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, in these methods, since solderability is hindered by performing alloy plating or post-treatment, these methods can hardly be put into practical use. Practical application due to optimization of composition and chromate treatment layer

Method used

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  • Environmentally friendly surface treated steel sheet for electronic parts excellent in soldering wettability and resistance to rusting and formation of whisker
  • Environmentally friendly surface treated steel sheet for electronic parts excellent in soldering wettability and resistance to rusting and formation of whisker
  • Environmentally friendly surface treated steel sheet for electronic parts excellent in soldering wettability and resistance to rusting and formation of whisker

Examples

Experimental program
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Effect test

preparation example Construction

[0018] The preparation method of the Sn-Zn alloy layer, in addition to electroplating Sn, Zn on the steel plate or nickel-plated steel plate, by performing thermal diffusion treatment to obtain the Sn-Zn alloy layer, can also be coated with Sn-Zn by direct electroplating on the steel plate. The Zn alloy method, or by the molten dip coating method, that is, the method of immersing the steel plate in a molten Sn-Zn alloy bath and coating. In addition, among the above-mentioned three methods, as described in JP-A-2-270970 and JP-A-3-183796, by using a steel sheet having a base nickel-plated layer as the above-mentioned steel sheet, it is possible to prepare the steel sheet at the steel sheet interface. A nickel-plated layer or a Fe-Ni diffusion layer is used to prepare a Sn-Zn alloy layer on the surface layer, and the present invention does not particularly limit the manufacturing method of the Sn-Zn alloy layer.

[0019] In addition, the Sn-Zn alloy layer in the present inventio...

Embodiment 1

[0031]After degreasing and pickling the low-carbon cold-rolled steel sheet that has been cold-rolled and annealed in the usual way, nickel-plating is performed sequentially under the treatment conditions shown in (1), and then nickel-plated with the treatment conditions shown in (2). Tin plating was performed under the conditions, and galvanization was performed under the conditions shown in (3). Afterwards, heat treatment is carried out in the air at a temperature of 250-350° C. on the surface of the steel sheet for more than 0.5 seconds by means of electric heating to form a coating film mainly composed of a Sn-Zn binary alloy. In addition, after post-processing under the conditions shown in (4) and (5), various evaluation tests were performed as a sample.

[0032] (1) Nickel plating

[0033] ① Bath condition NiSO 4 ·7H 2 O: 200~300g / L

[0034] h 2 SO 4 : 0~50g / L

[0035] h 3 BO 3 : 40g / L

[0036] ②Electroplating conditions Bath temperature...

Embodiment 2

[0056] After degreasing and pickling the low carbon cold-rolled steel sheet that is cold-rolled and annealed in the usual way, nickel-plated with the treatment conditions shown in (1) of Example 1 successively, with the following (6) The processing conditions shown in Sn-Zn alloy plated, with the conditions shown in Example 1 (4) to remove the surface oxide film. Thereafter, after performing the anti-oxidation coating film treatment under the conditions shown in (5) of Example 1, various evaluation tests were performed as samples.

[0057] (6) Sn-Zn molten alloy plating

[0058] ① Bath conditions Sn-Zn alloy

[0059] ②Electroplating conditions Bath temperature: 250~300℃

[0060] Dipping time: 1 second

[0061] Coating weight: 30~40g / m 2 (wipe control)

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Abstract

The present invention provides a surface treated steel sheet for electronic components which does not include lead, which is a hazardous substance with environmental impact, and, in particular, satisfies the solder wettability after retort treatment, a rust-proof property and a whisker-proof property simultaneously. More specifically, the present invention is a surface treated steel sheet with less environmental impact for electronic components excellent in solder wettability, a rust-proof property and a whisker-proof property and having an Sn-Zn alloy layer which is formed by plating Sn and Zn on a steel sheet or a Ni plated steel sheet and then applying thermal diffusion treatment, or by plating Sn-Zn alloy on a steel sheet or a Ni plated steel sheet, characterized in that the amount of said Sn-Zn alloy layer is not less than 3 g/m<2>, the Zn/Sn ratio (in weight ratio) is 0.01 to 10, more preferably 0.01 to 0.1, and an inorganic film mainly composed of magnesium phosphate is formed in the amount of 1 to 100 mg/m<2> in terms of the amount of P + Mg on said Sn-Zn alloy layer.

Description

technical field [0001] The present invention relates to a surface-treated steel sheet for electronic components of electrical products, which has excellent solder wettability, rust resistance, and whisker resistance, and does not contain environmental load substances such as lead. Background technique [0002] For electronic components of electrical products, especially surface-treated steel sheets excellent in solderability, tin-plated iron sheets, lead-tin-plated steel sheets, and solder-plated steel sheets are generally used. [0003] In this way, a surface-treated steel plate is used, which has excellent solder wettability to attach a solder layer by immersion in a molten solder bath for a short time, and the surface of the steel plate must be adhered to 8.4 to 11.2 g / m 2 Surface-treated steel sheets with a tin-plated layer (hereinafter referred to as #75~#100 tin-plated iron plates), but in recent years, the miniaturization of electrical products has narrowed the interv...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C22/07B23K35/00C22C13/00C22C18/00C23C2/02C23C2/26C23C26/00C23C28/00C23C28/02C23C30/00C25D5/10C25D5/48C25D5/50
CPCC23C28/3225C23C2/26C25D5/48C23C28/345B23K35/004C23C2/02C25D5/505C23C28/321C23C22/22C25D5/10C23C30/00C23C26/00Y10T428/12722Y10T428/12937Y10T428/12799Y10T428/12792Y10T428/12972Y10T428/12708C23C2/022C23C28/00
Inventor 吉原良一白川时次三浦泰彦
Owner NIPPON STEEL CORP
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