JPH0570994A - Production of tin plated terminal - Google Patents

Abstract

PURPOSE:To obtain the terminal having high surface hardness and good contact resistance by subjecting the surface of the terminal to tin plating, then irradiating this contact part with radiation energy, such as laser, to instantaneously melt only the tin plating layer. CONSTITUTION:The terminal is subjected to tin plating. The thickness thereof is preferably 0.5 to 5mum. This contact part is irradiated with the high-density energy, such as laser, to instantaneously melt the tin plating layer and is then immediately cooled to solidify. The contact part of the tin plating layer has the increased surface hardness and increased wear resistance.

Description

Description: FIELD OF THE INVENTION The present invention relates to a method of manufacturing a terminal having a durable electrical contact portion.

[Conventional technology]

 Since contact components used in many fields require stable and durable operation, their surface is usually plated with a metal with low contact resistance and excellent corrosion resistance, such as precious metal. Often. However, since precious metals are generally expensive, plating of inexpensive metals is often used even when there is difficulty in durability when economic efficiency is important. For example, tin plating is often used.

 The tin plating applied on the surface of such a terminal protects the inner part from further oxidation by forming a thin and dense oxide layer on the surface, but because the material is soft, the contact part does not rub. If worn, wear is likely to occur. Therefore, there is no particular problem when the frequency of sliding or attachment / detachment is low, but when it is high, the plating layer may be worn or oxidation may be promoted, resulting in poor contact.

[Problems to be Solved by the Invention]

 Therefore, an object of the present invention is to improve the wear resistance of an economical tin-plated terminal and to provide a terminal having a highly durable contact portion.

[Means for solving the problem]

 The above-mentioned object of the present invention is characterized in that, after tin plating is applied to the surface of the terminal, the contact portion is irradiated with radiant energy such as laser to instantaneously melt only the tin plating layer. This can be achieved by the method of manufacturing the plated terminal.

 In manufacturing a terminal by the method of the present invention, a press-molded terminal or a non-molded terminal is first tin-plated, but the tin-plating applied to the surface of the terminal is a commonly used electroplating method. The thickness is preferably 10 μm or less, and more preferably 0.5 to 5 μm. If the thickness is too thin, the improvement effect will be small, while if it is too thick, the effect depending on the thickness cannot be expected.

 Irradiation of radiant energy to modify the terminals is not limited to the contact area, but irradiation to areas other than the contact area is meaningless in practice and economically undesirable.

 The radiant energy applied to the surface of the contact portion of the terminal is preferably applied intermittently as a pulse, because the tin plating layer is momentarily melted and then immediately cooled and solidified. As such radiant energy, high-density energy such as laser beam, electron beam, TIG arc, etc. can be used. Of these, the ones that are easiest to handle and control are the various types of processing or medical treatment in recent years. Is a laser beam that has been widely used in the field of.

 In other words, the focus of the laser beam is easy to adjust, and continuous or pulse irradiation can be controlled arbitrarily, so by conducting preliminary experiments, for example, the size of the focus, the width and intensity of the pulse, and also the period of the pulse can be adjusted. The irradiation conditions such as the beam moving speed and the beam can be easily determined within an appropriate range.

[Work]

 According to the method for manufacturing a tin-plated terminal of the present invention, the contact portion of the tin-plated layer applied to the surface of the terminal has a high surface hardness and an increased wear resistance.

〔Example〕

 A 0.3 mm thick brass strip was stamped into a continuous terminal shape, preformed, and tin-plated to a thickness of approximately 3 μm. The surface was matte.

On the other hand, using a YAG laser device configured as shown in FIG. 1, the irradiation spot diameter was 0.1 mm, and argon gas was supplied as an assist gas at a flow rate of 10 l / min, while the contact portion of the above-mentioned terminal was about 2 mm. Irradiation treatment was performed on x3 mm. Laser irradiation was performed by changing the pulse intensity (w), pulse width (ms), pulse period (Hz) and beam moving speed (mm / s) as shown in Table 1, and the surface of the contact point obtained. Hardness (Knoop hardness) and contact resistance (mΩ) were measured. These results and the surface condition by visual observation are shown in Table 2, and micrographs of the treated surface and scanning electron micrograph are shown in FIGS. 2 and 3.

The surface of the contact portion subjected to the irradiation treatment by the method of the present invention had a dense and smooth appearance and had ring-shaped irregularities indicating that the irradiation spot was once melted and then rapidly solidified. When the crystal structure of the tin layer was examined by X-ray diffraction, the control sample had a β-type crystal structure mainly oriented in the crystal plane (220), whereas the sample according to the present invention had a crystal plane. It had a β-type crystal oriented to (203) or an amorphous structure.

〔The invention's effect〕

 According to the method for producing a tin-plated terminal of the present invention, a terminal having a high surface hardness at the contact portion and a good contact resistance can be obtained. Such terminals are economical to manufacture and have the advantage of withstanding long-term use.

[Brief description of drawings]

 FIG. 1 is an outline of a laser irradiation apparatus used for carrying out the method of the present invention, and FIGS. 2 and 3 are micrographs and scanning electron images of a treated or untreated surface by the method of the present invention, respectively. It is a micrograph. 1 ... Laser oscillator, 2 ... Terminal, 3 ... Contact part, 4 ... Computer, 5 ... Laser control part, 6 ... TV monitor, 7 ... Mirror, 8 ... Lens.

[Procedure amendment]

[Date of submission] Hei 3.2.21 1 The description on page 7, lines 6 to 8 of the specification has been corrected as follows. 2 (A), (B), and (C) are schematic views of micrographs showing the surface states of the terminals A, B, and C of the embodiment of the present invention, and FIG. 2 (D) of the present invention. It is the schematic of the microscope picture which shows the surface state of the terminal D of the control product which does not use the method. 3 (A), (B) and (C) are schematic views of scanning electron micrographs showing the surface states of the terminals A, B and C of the embodiment of the present invention, respectively, and FIG. It is a schematic diagram of a scanning micrograph showing the surface state of terminal D of a control article which does not use the method of the present invention. 2 Replace the attached Figures 2 and 3 with Figures 2 and 3 as attached.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Minoru Ikeda 1500 Onjuku, Susono-shi, Shizuoka Prefecture, Yazaki Sogyo Co., Ltd. (72) Inventor Hideaki Murata 1500, Onjuku, Susono-shi, Shizuoka Prefecture

Claims (1)

[Claims] 1. A method for producing a tin-plated terminal, characterized in that after the surface of the terminal is tin-plated, the contact portion is irradiated with radiant energy such as a laser to instantaneously melt only the tin-plated layer. .