JP4363261B2 - Electronic component having contacts and soldering terminals and surface treatment method thereof - Google Patents

Description

  The present invention relates to an electronic component such as a contact having a contact and a soldering terminal used as a connector or the like, and a surface treatment method thereof.

Conventionally, when connecting a terminal of an electronic component such as a contact to the surface of a circuit board by soldering, as the component becomes smaller, the solder tends to run up and the function and performance of the component are impaired. To do. If solder adheres to the contacts of electronic components, connection reliability will be impaired. Therefore, as a measure to prevent the solder from running up, an oxide film is provided on the surface near the terminals of the electronic component to reduce the wettability of the solder, and the solder that has run up from the circuit board is stopped by the oxide film (with the solder barrier and There is something that prevents it from reaching the contact portion. Here, in order to form an oxide film on the surface in the vicinity of the terminal, a method of partially irradiating a laser beam or the like is known (for example, see Patent Document 1).
Japanese Patent Laid-Open No. 8-213070

  However, in the method disclosed in the above publication, the solder barrier property is ensured, but there is a problem that the corrosion resistance is lowered because of partial heating for forming the oxide film. In addition, when a laser beam device is used, the cost is high.

  The present invention solves the above problem, and when soldering and mounting an electronic component on a circuit board, while preventing the solder from sucking up in the contact direction, the corrosion resistance is improved and the cost is reduced. An object of the present invention is to provide a surface treatment method for an electronic component having a contact and a soldering terminal.

To achieve the above object, the invention of claim 1 is a surface treatment of an electronic component formed by processing a metal plate, and having a contact portion at one end and a terminal portion soldered and mounted on a circuit board at the other end. In the method, a noble metal plating layer is formed so that the contact portion and the terminal portion become a thick film on the surface layer of the metal plate subjected to the base plating treatment on the surface of the metal plate, and a thin film on the other portions. By uniformly heat-treating with the forming step, nickel is diffused selectively on the surface of the thin noble metal plating layer using the difference in plating film thickness , and the diffused nickel is oxidized to form a solder barrier. And a step of forming an oxide film.

  In this method, a thick noble metal plating layer is electrodeposited on the contact portion and the soldering terminal portion, and a thin noble metal plating layer is electrodeposited on the other portions. Since there is such a difference in the thickness of the noble metal plating, when heat treatment is carried out uniformly, an oxide film is formed by diffusion of the underlying nickel in the portion where the surface film is thin, but the contact part and the soldering terminal part are formed on the surface layer. Since the film is thick, no oxide film is deposited. As a result, the contact portion and the soldering terminal portion have good solder wetting, but other portions serve as solder barriers. In addition, the oxide film thus generated by thermal oxidation insulates the corrosion current, and is effective in suppressing corrosion resistance.

The invention of claim 2 is the oxide film forming step mentioned above, instead of applying a heat treatment, it performs a process of contacting the chemical oxidant. In this method, the same effect as described above can be obtained. In addition, since the oxide film generated by the chemical oxidant insulates the corrosion current, it is effective for enhancing the corrosion resistance.

Further, the invention of claim 3 is a nickel plating treatment in a bath containing a nickel plating additive for reducing nickel plating particles in the base nickel plating treatment step. Even in this method, the same effect as described above can be obtained, and by selecting an appropriate type of additive to be added to the nickel plating, the size of the nickel plating particle diameter precipitated by the additive is reduced. Nickel is more easily diffused on the surface.

  According to a fourth aspect of the present invention, plasma treatment is used as uniform heat treatment in the oxide film forming step. In this method, the oxide film generated by the plasma treatment insulates the corrosion current, and is effective for enhancing the corrosion resistance.

The invention of claim 5 is characterized in that in the base nickel plating treatment step, a base nickel layer and a base palladium-nickel layer are formed on the surface layer, and in the oxide film formation step, the base palladium-nickel layer is formed. An oxide film is formed by diffusing and oxidizing nickel in the surface layer of the noble metal plating layer . In this method, since the palladium alloy layer is used for the base, the corrosion resistance is further enhanced.

According to a sixth aspect of the present invention, in the base nickel plating process, a base nickel-phosphorus layer is formed, and in the oxide film forming step, nickel in the base nickel-phosphorus layer is used as a surface layer of the noble metal plating layer. An oxide film is formed by diffusing and oxidizing . In this method, since phosphorus is introduced into the underlying nickel layer to form an alloy layer, the corrosion resistance is further enhanced.

  In a seventh aspect of the invention, a nickel layer is formed on the base of the base nickel-phosphorus layer in the base nickel plating treatment step. In this method, the nickel-phosphorus layer is inferior to the nickel layer in soldering strength, but by placing nickel on the nickel-phosphorus layer base, the soldering strength is secured, and the nickel-phosphorus alloy layer is Productivity cannot be improved due to the nature of the plating solution, but productivity can be improved by plating the nickel plating layer thickly on the base.

In the invention of claim 8, in the base nickel plating process, a base nickel layer not containing sulfur is formed, and in the oxide film forming step, nickel in the base nickel layer not containing sulfur is used as the noble metal. An oxide film is formed by diffusing and oxidizing the surface of the plating layer . In this method, since the underlying nickel layer does not contain sulfur, the corrosion resistance is further enhanced.

According to a ninth aspect of the present invention, the contact portion is a contact for a narrow pitch connector, and the terminal portion is configured to be SMD- mountable on a circuit board. In this method, it is possible to secure solder barrier properties and improve corrosion resistance when mounting a narrow pitch connector for SMD mounting.

According to a tenth aspect of the present invention, there is provided a surface treatment method for an electronic component which is formed by processing a metal plate and has a contact portion at one end and a terminal portion soldered and mounted on a circuit board at the other end. And the surface layer of the metal plate subjected to the base plating treatment, the contact portion becomes a film having a thickness of about 0.2 μm, and the other portion including the terminal portion has a film thickness of 0.05 μm or less. As described above, the step of forming the noble metal plating layer under different electrodeposition conditions and the use of the difference in plating film thickness to selectively diffuse nickel into the surface layer of the noble metal plating layer having a thickness of 0.05 μm or less , and the nickel And an oxide film to be a solder barrier is formed. In this method, for example, the contact portion is thick-film plated with a normal noble metal plating solution, but the terminal portion is subjected to ultra-thin plating with an ultra-thin noble metal plating solution, thereby enhancing the solder barrier action at the terminal portion. be able to.

The invention of claim 11 is an electronic component formed by processing a metal plate, and having a contact portion at one end and a terminal portion that is SMD-mounted by soldering to a circuit board at the other end, A nickel-plated base plating layer, a noble metal plating layer formed on the surface layer of the base plating layer so that the contact portion and the terminal portion are a thick film, and the other portions are thin films, and the thin noble metal An oxide film serving as a solder barrier formed by diffusing nickel into the surface layer of the plating layer and oxidizing the nickel to form a film is provided. In this electronic component, the same effect as in the ninth aspect can be obtained.

  According to the present invention, by using a uniform heat treatment or chemical oxidation treatment, the base plating film component is diffused to the outermost layer and oxidized, thereby preventing the solder from sucking up in the contact direction when mounting the electronic component, that is, the solder barrier. In addition, the oxide film generated by thermal oxidation insulates the corrosion current, so that the improvement of the corrosion resistance can be ensured.

  Hereinafter, an electronic component having contacts and terminals according to an embodiment of the present invention and a surface treatment method thereof will be described with reference to the drawings. FIG. 1 shows a contact used for an electronic component such as a connector according to the present embodiment. The contact 1 is formed by bending a band-shaped metal plate such as copper having a spring property into a predetermined shape, and has a terminal portion 2 soldered to a circuit board on one end side, and a contact portion 3 on the other end side. Have The surface of the contact 1 is entirely subjected to base plating by nickel plating. On the base plating, as noble metal plating, for example, a gold plating region 4 on the terminal portion 2 side subjected to gold plating, a gold plating region 5 on the contact portion 3 side, and between the gold plating regions 4 and 5 A solder barrier portion (an oxide film region to be described later) 6 for preventing the diffusion (solder rising) of the molten solder is formed.

  FIG. 2 shows a state in which a socket in which the contact 1 is housed is mounted on a circuit board. The socket 100 includes a socket base 101 formed in a frame body with an insulating resin, a plurality of pairs of contacts 1 inserted into the socket base 101, and the like, and is mounted on the circuit board 110. The terminal portion 2 of the contact 1 protrudes below the lower surface of the socket base 101 and is soldered to the surface of the wiring pattern on the circuit board 110. Thereby, the socket 100 is fixed on the circuit board 110. At this time, since the surface of the terminal portion 2 is gold-plated, the melted solder 111 is formed on the surface of the terminal portion 2 and the wiring pattern on the circuit board 110 due to the high wettability of gold and solder. It flows in between and adheres to the surface. On the other hand, the solder adhering to the surface of the terminal portion 2 diffuses on the gold plating region 4 but cannot diffuse to the other gold plating region 5 due to the presence of the solder barrier portion 6. As a result, the solder 111 does not adhere to the contact portion 3. Note that a header (not shown) constituting the connector, which is the counterpart of the socket 100, has the same configuration.

  FIGS. 3A, 3B and 3C show a semi-finished product 12 in which a large number of contacts 1 are arranged before being inserted into a socket. The contact 1 is, for example, used for a connector for a portable device and has a very small shape. Therefore, the side portion of the belt-shaped metal plate is formed in a comb shape and the comb portion is bent into a predetermined shape. Thus, a large number of contacts 1 are arranged at a predetermined pitch. Then, the semi-processed product 12 is conveyed while being positioned by the guide hole 20 and immersed in a nickel bath, whereby a nickel base plating layer is formed on the entire surface of the contact 1. Further, the gold plating layer is formed on the entire surface of the base plating layer by immersing it in the gold plating bath while conveying the semi-processed product 12.

  In this manner, after the gold plating layer is formed on the surface of the contact 1 including the terminal portion 2 and the contact portion 3, the processing according to each embodiment described later is performed between the terminal portion 2 and the contact portion 3. As a result, a predetermined solder barrier section 6 (see FIG. 1) is formed. The solder barrier portion 6 is preferably provided at a location close to the terminal portion 2 in consideration of the bonding strength with the wiring pattern and the like. After forming the solder barrier portion 6, the semi-processed product 12 is inserted into the socket base 101 (FIG. 2), and each contact 1 is cut off from the semi-processed product 12 to complete the socket 100. Thereafter, the socket 100 is disposed on the circuit board 110, and the terminal portion 2 of the contact 1 is soldered to the wiring pattern, whereby the socket 100 is mounted on the circuit board 110.

  Next, each embodiment of the configuration of the base plating and gold plating regions 4 and 5 of the contact 1 and the solder barrier section 6 and the surface treatment method will be described.

  FIG. 4 shows a process procedure of the surface treatment method according to the first or second embodiment. In this process, the step of plating the metal plate with the base nickel plating (S1), on the surface layer of the metal plate subjected to the base plating treatment, the contact portion and the terminal portion become a thick film, and the other portions become a thin film. A step of forming a noble metal plating layer (S2), and a step of forming an oxide film by diffusion of underlying nickel on the surface layer of the thin noble metal plating layer by performing uniform heat treatment or chemical oxidation treatment (S3). . In this process, a selective oxide film is formed using the difference in thickness of the plating film. The noble metal plating layer of the thick film of the contact part and the terminal part becomes the gold plating regions 4 and 5 (when gold is used as the noble metal), and the oxide film formed on the other noble metal plating layer is a solder barrier. It becomes part 6.

  FIG. 5 schematically shows a configuration on the surface layer side of the base plating layer on which the surface treatment of FIG. 4 has been performed. a is a base nickel plating, b is a thick gold plating, c is a thin gold plating, and d is an oxide film. In the following embodiments, description of the basic processing described above will be omitted, and only the characteristic part will be described.

<First Embodiment>
This surface treatment is characterized in that a selective oxide film is formed using a difference in thickness of the outermost noble metal plating film. In order to prevent the solder from sucking up during mounting and to reduce the cost of precious metals, plating is performed mainly on the parts where the outermost surface precious metal film is required, such as contacts and soldering terminals (hereinafter referred to as partial plating). Examples of the outermost noble metal film include gold plating. When a part to be subjected to partial plating is fine, the plating solution may bleed from a target portion for plating. Since the film is electrodeposited even on the portion where the plating solution is blotted, a noble metal film is formed. For this reason, the contact and soldering terminal portions are electrodeposited thickly, and the other portions are electrodeposited thinly. When heat treatment or the like is uniformly applied to a product with such a difference in thickness in the plating thickness, an oxide film is formed by diffusion of the underlying nickel in the portion where the outermost layer film is thin. Since the outermost layer is thick, the oxide film is not deposited. By providing such an oxide film, the contact point and the soldering terminal portion have good solder wettability, but other portions serve as solder barriers. And since the oxide film produced | generated by thermal oxidation insulates a corrosion current, it becomes effective also in suppression of corrosion resistance.

Second Embodiment
This surface treatment is characterized in that an oxide film is formed on a thin part of the outermost noble metal plating film using a chemical oxidizing agent. If a product with a difference in density in the plating thickness is uniformly subjected to chemical oxidation treatment, etc., an oxide film is formed by diffusion of the underlying nickel in the portion where the outermost layer film is thin. Since the surface layer is thick, no oxide film is deposited. This oxide film can be formed using, for example, the following chemical oxidant. An example of a chemical oxidant: nitric acid, hypochlorous acid, etc. Temperature: above room temperature, stirring is more effective.

<Third Embodiment>
This surface treatment is characterized by modifying the nickel plating so that the plating film is easily oxidized. Oxide films can be obtained with commonly used Watt bath nickel plating and nickel sulfamate, but by selecting the most appropriate type of additive to be added to the nickel plating, the nickel film can be easily oxidized. it can. It is considered that the size of the nickel plating particle diameter precipitated by this additive is reduced and more easily diffused to the surface.

<Fourth embodiment>
This surface treatment is characterized in that an oxide film is formed by plasma treatment on a portion where the outermost noble metal plating film is thin. Since the oxide film generated by the plasma treatment insulates the corrosion current, it is effective for enhancing the corrosion resistance. Alternatively, the noble metal plating film may be an extremely thin film, and an oxide film may be formed thereon. The outermost noble metal plating layer on the nickel plating may be made extremely thin in order to reduce the precious metal cost. When thermal processing or the like is performed on such an extremely thin noble metal plating, an oxide film is formed by diffusion of the underlying nickel. An example is given below. Oxidation source: Heat treatment by halogen lamp, high frequency heating, plasma treatment, etc.

<Fifth Embodiment>
This surface treatment is characterized in that an oxide film is formed on the noble metal film by diffusion oxidation treatment of the base palladium-nickel layer on the noble metal plating film, thereby realizing a solder barrier effect and enhanced corrosion resistance. Applied to narrow pitch connectors. Since the palladium alloy layer is used for the base, the corrosion resistance is further enhanced.

<Sixth Embodiment>
This surface treatment is characterized by forming an oxide film on the noble metal film by diffusion oxidation treatment of the base nickel-phosphorus layer in the noble metal plating film, realizing a solder barrier effect and enhanced corrosion resistance, Applied to narrow pitch connectors. Since phosphorus is introduced into the underlying nickel layer to form an alloy layer, the corrosion resistance is further enhanced.

<Seventh embodiment>
This surface treatment is applied to a narrow pitch connector in the above embodiment, in which a nickel layer is further provided on the base of the nickel-phosphorus layer to improve soldering strength and productivity. The nickel-phosphorous layer is inferior to the nickel layer in soldering strength. However, the nickel-phosphorous layer has nickel on the base to ensure the soldering strength. Although productivity cannot be improved, productivity can also be improved by thickly plating the nickel plating layer on the base.

<Eighth Embodiment>
This surface treatment is characterized by the fact that an oxide film is formed on the noble metal film by diffusion oxidation treatment of the base nickel layer that does not contain sulfur in the noble metal plating film, thereby realizing a solder barrier effect and enhanced corrosion resistance. And applied to narrow pitch connectors. Since the underlying nickel layer does not contain sulfur, the corrosion resistance is further enhanced.

<Ninth Embodiment>
This surface treatment is characterized by the fact that the base nickel on the precious metal plating film is diffused and oxidized to form an oxide film on the precious metal film, realizing a solder barrier effect and enhanced corrosion resistance. This was applied to a narrow pitch connector of SMD mounting. When mounting a narrow pitch connector for SMD mounting, it is possible to secure solder barrier properties and improve corrosion resistance. In each of the above embodiments, SMD mounting is basically used, but is not limited thereto.

<Tenth Embodiment>
This surface treatment is characterized in that gold plating does not spread on the solder barrier portion by treating the connector terminals and the contacts under different electrodeposition conditions. Even with a thick gold plating thickness, the solder crawls up and does not become a solder barrier. Therefore, for example, the contact portion is treated with a normal thick gold plating solution, but the terminal portion is subjected to ultra thin plating with an ultra thin gold plating solution. Normal thick gold plating: about 0.2 μm , ultrathin gold plating: 0.05 μm or less. Thereby, since gold plating does not spread and adhere to the solder barrier portion, processing such as gold peeling processing or thermal processing becomes unnecessary. As another method of changing the electrodeposition conditions, there is a method of increasing the current density of the contact and the terminal portion and minimizing the current density of the solder barrier portion.

Specific examples are shown below.
Example 1: Prevention of solder uptake during mounting when heat is applied to a part composed of a noble metal-based film / nickel-based / copper-based material or outermost layer noble metal plating A / noble metal plating B / nickel-based metal / copper-based material ( = Solder barrier properties) and corrosion resistance improved. The processing conditions are shown.
(Thermal processing conditions)
Heat source: Near infrared heater use (Hybeck: HYL-2520), Irradiation conditions: Work distance to parts: 24 mm, Lamp: 200 V, 2500 W, Output: 12.1 A, Spot diameter: 2 mm, Work temperature: 400 ° C. 800 ° C
(Sample work conditions)
Sample A: Au (0.06-0.3 μm ) / Ni (1.5 μm ) / Cu (0.1 mm), Sample B: Au (0.06-0.3 μm ) / Pd− Ni (8: 2, 0.3 μm ) / Ni (1.5 μm ) / Cu (0.1 mm),
(Experimental result)
The results for samples A and B are shown in the table below. From this experimental result, the optimum result was obtained when the peak temperature of thermal processing was about 700 ° C.

  In the above experiment, peak temperature: 260 degrees, solder: Sn-Ag2.0-Cu0.5, nitrogen reflow CASS test, salt spray test, 5 wt% -sodium chloride solution, sulfurous acid gas, 10 ppm concentration, 40 ° C., 95% RH. .

The perspective view of the contact used for electronic parts, such as a connector concerning the embodiment of the present invention. Sectional drawing which shows the state which mounted the socket by which the contact was equipped internally on the circuit board. (A) (b) (c) is a side view, a front view, and a side view showing a semi-processed product in which a large number of contacts before being inserted into a socket are arranged. The figure which shows the process sequence of the surface treatment method of 1st thru | or 2nd embodiment. The figure which shows typically the structure of the surface layer side rather than the base plating layer to which surface treatment was given.

Explanation of symbols

1 Contact (including metal plate)
2 Terminal part 3 Contact part 4 Gold plating area (noble metal layer)
5 Gold plating area (precious metal layer)
6 Solder barrier (oxide film)

Claims (11)

In a surface treatment method of an electronic component formed by processing a metal plate, having a contact portion at one end and a terminal portion soldered and mounted on a circuit board at the other end,
A step of nickel plating the metal plate,
A step of forming a noble metal plating layer on the surface layer of the metal plate subjected to the base plating treatment so that the contact portion and the terminal portion become a thick film and the other portions become a thin film;
By uniformly heat-treating, nickel is diffused selectively on the surface of the thin noble metal plating layer using the plating film thickness difference , and the diffused nickel is oxidized to form an oxide film serving as a solder barrier. And a process of
A surface treatment method for an electronic component, comprising: Wherein the oxide film forming step, instead of heat treatment, surface treatment method for an electronic component according to claim 1, wherein the performing processing of contacting the chemical oxidant. 3. The surface treatment method for an electronic component according to claim 1, wherein in the base nickel plating treatment step, the nickel plating treatment is performed in a bath containing a nickel plating additive that reduces nickel plating particles . 4.   2. The surface treatment method for an electronic component according to claim 1, wherein a plasma treatment is used as the uniform heat treatment in the oxide film forming step. In the base nickel plating treatment step, a base nickel layer and a base palladium-nickel layer on the surface layer are formed,
The oxide film is formed by diffusing and oxidizing nickel in a base palladium-nickel layer in a surface layer of the noble metal plating layer in the oxide film forming step. Electronic component surface treatment method. In the base nickel plating treatment step, a base nickel-phosphorus layer is formed,
The oxide film is formed by diffusing and oxidizing nickel in a base nickel-phosphorus layer in a surface layer of the noble metal plating layer in the oxide film forming step. Electronic component surface treatment method.   7. The surface treatment method for an electronic component according to claim 6, wherein a nickel layer is formed on a base of the base nickel-phosphorus layer in the base nickel plating process. In the base nickel plating treatment step, a base nickel layer not containing sulfur is formed,
3. The oxide film is formed by diffusing and oxidizing nickel of a base nickel layer not containing sulfur in a surface layer of the noble metal plating layer in the oxide film forming step. The surface treatment method of the electronic component of description. Wherein a contact of the contact portions for a narrow pitch connector, a surface treatment method for an electronic component according to claim 1 or claim 2 wherein the terminal portion is characterized in that it is configured to be SMD mounted on the circuit board. In a surface treatment method of an electronic component formed by processing a metal plate, having a contact portion at one end and a terminal portion soldered and mounted on a circuit board at the other end,
A step of nickel plating the metal plate,
Under different electrodeposition conditions, the surface of the metal plate subjected to the base plating treatment has a film with a contact portion of approximately 0.2 μm, and the other portion including the terminal portion has a film thickness of 0.05 μm or less. Forming a noble metal plating layer;
A step of selectively diffusing nickel into a surface layer of a noble metal plating layer having a thickness of 0.05 μm or less using a difference in thickness of the plating film and oxidizing the nickel to form an oxide film serving as a solder barrier;
A surface treatment method for an electronic component, comprising: An electronic component formed by processing a metal plate, having a contact portion at one end and a terminal portion that is SMD-mounted by soldering to a circuit board at the other end,
A base plating layer obtained by nickel-plating a metal plate;
On the surface layer of the base plating layer, the noble metal plating layer formed so that the contact part and the terminal part become a thick film, and the other part becomes a thin film,
An oxide film serving as a solder barrier formed by diffusing nickel into the surface layer of the thin noble metal plating layer and oxidizing the nickel; and
An electronic component characterized by comprising:

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