JPS5844758B2 - Barrel plating method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a barrel plating method, particularly to a dummy used together with the object to be plated in the plating process.

As shown in FIG. 2, the reed switch consists of a glass tube 11 and reed pieces 12 and 13 sealed in the glass tube.

The lead piece portion, ie, the terminal portion, protruding from the glass tube 11 is plated with tin (Sn) or the like, and a barrel method is convenient for carrying out this plating.

Figure 1 shows the barrel tank used in this plating method, where 1 is the main body of the barrel tank 8, 2 is a mesh such as Saran net stretched inside the frame, 3 is a barrel support shaft that also serves as an electrode, and 4 is a barrel tank used in this plating method.
, 5 is a support arm of the shaft 3, and 6 is a plurality of auxiliary electrodes provided on the shaft 3 at intervals so as to project downward.

A large number of reed switches 10 whose terminals are to be plated are placed in a barrel tank 8 together with a large number of dummy balls 7, and the barrel tank is immersed in a spout tank 9 containing an electrolytic solution, and a negative voltage is applied to the shaft 3. Plating is performed while applying a positive voltage to an electrode (not shown) in the tank and rotating the valve tank 8.

A current path is formed by the rotating shaft 3 serving as an electrode, the auxiliary electrode 6, the dummy ball 7, the terminal portion of the reed switch 10 (the contact of the reed switch is generally open), and the electrode in the plating bath after electrolysis.

Due to the rotation of the barrel tank 8, the reed switch 10 and the dummy ball 7 charged into the lower space of the tank first rotate by a predetermined angle together with the barrel tank 8, and then fall down from the side that was raised higher, and this is repeated until they are stirred. , this makes the plating uniform.

The auxiliary electrode 6 ensures that a current-carrying path is formed, and protrudes into the stack of the dummy balls γ and the reed switch 10 and comes into contact with the terminals of the dummy balls and/or the reed switch to form an electric circuit.

This contact can also be made by loading a large amount of reed switches and dummy balls into the barrel tank 8, to the extent that they fill the center support shaft 3, but if such a large amount is inserted, the overall weight will be reduced. Moreover, since stirring is carried out while violently colliding with each other, the terminal portions of the reed pieces 12 and 13 protruding from the glass tube 11 of the reed switch may be bent.

Reed switch 10 and dummy ball 7 are in barrel tank 8
If a small amount is placed only in the lower space below the axis 3 of the auxiliary electrode 6 and the electric circuit is formed using the auxiliary electrode 6, plating can be performed without bending the terminal portion.

The dummy ball 7 enters between a large number of reed switches 10 to help stir the reed switches, and also serves as a relay medium so that the terminal portions of the reed switches are in reliable contact with the electrodes 3 and 6.

Therefore, the dummy balls must be electrically conductive, enter the reed switch group during the rotation of the barrel tank 8, mix well, and contact the terminal pieces well.

Conventionally, a metal ball has been used as this dummy ball.

However, in this case, the specific gravity of the metal ball is much greater, so the reed switch is on top and the metal ball is on the bottom, and there is a tendency for the two to separate.

This tendency becomes even more pronounced when the metal ball is plated and its weight increases.

In such a state, the terminal portion of the reed switch that is lifted up and disconnected in terms of circuitry is not plated, resulting in uneven plating.

Note that unless the plating thickness of the reed switch terminal is 5 μm or more, solderability and corrosion resistance will not be sufficient.

If the plating thickness is uneven and some parts are too thin, there is no choice but to reject the entire plating unless you go through the troublesome process of measuring and sorting the thickness of each plating, and to avoid this, excessive Plating must be done so that nothing is too thin, increasing plating time, power requirements, and materials.

In addition, the present invention aims to obtain a dummy that can be mixed well into the reed switch terminal portion, that is, the object to be plated, and can reliably contribute to the formation of an electric circuit, thereby making uniform plating possible. be.

The barrel plating method of the present invention uses a dummy made of a plastic sphere or cylinder with a conductive film coated on the surface, the dummy is placed in a barrel tank together with the object to be plated, and the barrel tank is placed in a plating tank. The plating process is characterized in that plating is carried out by immersing the plate in water and applying electricity while rotating it.This will be described in detail below with reference to Examples.

In the present invention, as a dummy, a sphere made of spherical plastic such as ABS resin, whose surface is electrolessly plated with copper, is used.

The dummy has a low specific gravity, can be mixed well with the reed switch to be plated, and does not bend the terminal portion of the reed switch.

Furthermore, this dummy must be effective in forming a current-carrying circuit to the reed switch terminal portion, and its diameter is determined as follows.

That is, in FIG. 3, 7 is the plastic dummy ball, 10
a is the terminal part of the reed switch, X is the radius of the dummy ball,
d is the radius of the terminal portion, but in order to ensure that the terminal portion 10a comes into good contact with the dummy ball 7 and is reliably connected to the electrodes 3 and 6, x and d should have the following relationship. In other words, as shown in FIG. 3, the terminal portion 10a is preferably large enough to fill the cavity V formed by the aggregate of the dummy balls 7. In this case, the terminal portion 10a is supplied with current from all sides so that the current is uniformly supplied to the terminal portion 10a. Plated.

The conditions for the terminal part to fit tightly into the cavity are (x+d) = 4%//7X,", X-(J71)d...(1)
It is.

Even if the dummy ball is smaller than that shown in FIG. 3, it can cover the periphery of the terminal portion 10a and make good contact with the terminal portion, so the relationship in equation (1) is X≦(v'2+1)d... 2).

However, if the diameter of the dummies is made small, the number of dummies increases, and the surface area of the dummies also increases, increasing plating loss.

Therefore, it is appropriate to use the relationship expressed by equation (1).

The radius of the terminal portion of the reed switch is, for example, 0.5 mm, whereas the radius of the dummy is 1.2 mrn or less.

However, plastic spheres with a micro radius are difficult to manufacture and therefore expensive.

A cylindrical body instead of a sphere may be used instead, since this is easier to manufacture and therefore less expensive.

However, in the case of a cylindrical body, mixing of spheres and circuit formation are not good, and therefore a large amount needs to be used.

If there are a large number of dummies, naturally there will be a small amount of wave-plated reed switches, which will reduce the throughput of the plating equipment and also cause more waste because the dummies will also be plated.

Therefore, the spherical plastic dummy is superior in terms of characteristics.

Even if the diameter of the spherical plastic dummy is selected according to equation (2), the diameter will increase due to plating during use and the weight will increase, but this can be removed at an appropriate time by melting, electrolysis, etc.

The type of plastic may be other than ABS resin, and the conductive film applied to the surface of the dummy may be made of a suitable copper-based material with good conductivity.

Furthermore, in addition to electroless plating, vapor deposition or other methods may be used to apply the conductive film to the dummy surface.

[Brief explanation of the drawing]

Figures 1a, b, and C are front and end views of the barrel tank;
2 is an explanatory diagram of the reed switch, and FIG. 3 is an explanatory diagram of the optimum dummy diameter. In the drawing, 7 is a dummy, 8 is a barrel tank, 9 is a plating tank, and 10 is
a, 12.13 are objects to be plated.

Claims (1)

[Claims] 1. Using a dummy made of a plastic sphere or cylinder with a conductive film coated on the surface, the dummy is placed in a barrel tank together with the object to be plated, and the barrel tank is immersed in the plating tank. A barrel plating processing method characterized by plating by applying electricity while rotating. 2 The radius of the dummy is X<
The barrel plating method according to claim 1, characterized in that the relationship is determined to be (J2+1)d. 3. The barrel plating method according to claim 1 or 2, wherein the dummy is made of a spherical plastic sphere such as ABS resin. 4. The barrel plating method according to any one of claims 1 to 3, wherein the conductive film is formed by electroless plating of a highly conductive metal such as copper.