JPS5857214A - Lead switch - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an offset type reed switch in which the contact position is shifted from the center of the glass tube to the right or left side in the longitudinal direction thereof. The general structure of this type of reed switch is shown in FIG. In the figure, 1 is a glass tube, 2 and 3 are magnetic materials such as 52 alloy (Ni: 529be Fe: 4
A contact portion 4 is enclosed in a glass tube 1, with the tips of the leads 2 and 3 facing each other (overlapping) with a certain distance (gap) between them. has been done.

As shown in the figure, the contact part 4 is shifted from the center of the glass tube 1 to the right or left side in the longitudinal direction of the glass tube 1. 2,
3 is magnetically attracted or separated to open and close the contact current.

By the way, in a conventional offset type reed switch, the contacts of leads 2 and 3 are both made of hard precious metals such as Rh (*dium) and Rh (ruthenium), or Au (gold), as in a normal reed switch. )tA, (silver) and other soft noble metals. However, the former has the disadvantage of providing a long-life contact, but because it is hard, the contact area between the contacts is small and the contact resistance is large. 19 In the latter case, the contact area between the contacts is large because it is soft.)
Although a product with low contact resistance can be obtained, it has the disadvantage that as the number of opening and closing operations increases, the contacts tend to stick, making it impossible to obtain a long-life product.

The present invention is intended to easily solve these contradictory problems, and the present embodiment will be explained below with reference to FIGS. 2 and 3.

In the reed switch according to the present invention, as shown in an enlarged view of the contact portion 4 in the side cross-sectional view of FIG. An Au plating layer 6 made of a soft precious metal is formed on the tip surface, and an Ass plating layer 7 as a base is formed below the Rh plating layer 5. Below the plated layer 6 is a Cu (copper) plated layer 91 and layer 8 which serves as a base and prevents the lead 3 itself from diffusing into the Au plated layer 6.
0 Next, the results of a contact performance test between the reed switch according to the present invention and a conventional one will be explained with reference to FIG.

In Figure 3, the vertical axis (logarithmic scale) is the contact resistance defective rate,
The horizontal axis is the number of screenings (number of tests), and this test shows the proportion of resistance defects in manufactured reed switches and how many times screening must be performed to eliminate defective reed switches.

In the figure, the broken line A is the characteristic of the reed switch according to the present invention,
This means that the short lead 2 is first attached to its tip surface by approximately 0.5-
A base Au plating layer 7 is formed to a thickness of approximately 2 μm thick, and a Rh plating layer 5 serving as a contact surface is formed thereon to a thickness of approximately 2 μm.

In addition, the long side lead 3 has a tip surface of approximately 0.5 m.
A base Cu plating layer 8 is formed to a thickness of approximately 2.5 mm, and then an Au plating layer 6, which will become the contact surface, is formed to a thickness of approximately 2.5 mm, and then this is heated in a hydrogen atmosphere. Diffusion treatment (60
The Au--Cu alloy is manufactured by heating at 0° C. to 900° C., preferably at 700° C. to 800° C. for about 15 minutes. The two-dot chain line B is also a characteristic of the reed switch according to the present invention,
In the case of dashed line A, the Au plating layer 6 is formed directly on the long lead 3.1. This is a case where the Cu plated layer 8 is removed.

The dashed line C is the characteristic of the conventional reed switch, which is broken #
Contrary to the case of humans, that is, short one-side lead 2KCm, Kiki layer 8
(0,5, am thickness) - Ats plated layer 6 (25μ thickness)
The long side lead 3 has an Au plated layer 7 (0,5jIIK thickness) and a Rh plated layer 5 (2sIIIK thickness).
The 0 solid line (thickness) is also a characteristic of conventional reed switches, and this is because both the end surfaces of the short lead 2 and the long lead 3 are coated with an Au plating layer 7 (0,5j thickness) - Rh.
It is formed on the plating layer 5 (2μ thick).

In addition, by using the above-mentioned leads 2 and 3, an offset type reed switch as shown in Fig. 1 can be made with the same shape and 4s class 1000 each.
Manufactured one by one.

The shape of this reed switch is that the long and short leads 2 and 3 are made by crushing 527 mm wire with a length of approximately 29 mm and a diameter of approximately 0.56 mm, and the glass tube 1 is approximately 15 mm in length.
The length of the long lead 3 in the glass tube 1 is approximately 11 mm, and the short lead 2 is approximately 4 cm in diameter. The amount of V pull was 0.310.
After opening and closing a predetermined number of times under mA conditions, the first contact resistance measurement is performed, and at this time, reed switches with a value of 150 saΩ or more are determined to be defective and removed, completing the first screening, and the remaining non-defective products are removed. Open and close the reed switch again for a predetermined number of times to remove unnecessary items (2nd screening), and then further! ! The results of a third screening of the good quality reed switches were shown in Figure 3.As is clear from the above experimental results, the reed switch (Al The reed switch according to the present invention (At
n) had a contact life of 10f times, which is almost the same as the conventional Rh-Rh contact (D reed switch). ・One more conventional example is Au.
- Although the reed switch with an An contact is not shown in FIG. 3, it has a slightly lower failure rate due to contact resistance than the reed switch of the present invention, but its reverse contact life is 1710.
It is less than or equal to 0.

As described above, the reed switch according to the present invention has a low contact resistance failure rate and a long service life, and the effect on its use is remarkable.In addition, in the above example, the Au-Rh (1) combination was shown. However, the present invention is not limited to kneading, and the short lead is made of a hard precious metal such as Ru, and the long lead is made of A.
It may also be formed of soft metal such as tsCu.

[Brief explanation of the drawing]

Fig. 1 is a side view showing the general structure of the offset type reed switch to which the present invention applies, Fig. 2 is an enlarged 11 cross-sectional view of the reed switch contact portion according to the present invention, and Fig. 3 is a cross-sectional view showing the reed switch of the present invention. FIG. 2 is a graph showing a conventional measurement result of poor contact resistance; [Explanation of symbols] 2・・・・・・・Short one side lead, 3・・・・・・・・・
...Long side lead 4...Contact part, 5...
・・・・・・Rh layer, 6・・・・・・Au layer 1st figure now 2nd figure

Claims (3)

[Claims] (1) An offset type reed switch characterized in that the contact point of the long side lead is made of a soft metal such as Au, Af, or Cu, and the contact point of the short side lead is made of a hard precious metal such as Rh or Ru. (2) The reed switch according to claim (1), wherein the soft metal is Au and the hard noble metal is the enemy. (3) Claim Q, characterized in that the Au base layer is Cu-plated and subjected to thermal diffusion treatment.
) Reed switch listed in section.