JPH0736426B2 - Glass sealed diode - Google Patents

Description

TECHNICAL FIELD The present invention relates to a glass-sealed diode.

2. Description of the Related Art FIG. 5 shows a conventional example of this type of glass-sealed diode (literature unknown). There, electrodes 2 and 2 inserted in a glass tube 1 having a circular cross section are fused under a nitrogen gas atmosphere, and a diode chip 3 is clamped and fixed between the electrodes 2 and 2. The electrode 2 is formed by forming a Dumet wire into a round bar shape with a flange. Here, the Dumet wire is made of, for example, an iron-nickel alloy as a core material, surrounded by copper, and the surface of the copper is coated with a copper oxide film. Is coated with.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the above-described conventional example, the round bar portion 21 of the electrode 2 fused to the glass tube 1 is formed in a circular cross section having an outer diameter substantially equal to the inner diameter of the glass tube 1. Since it was a thing, when the electrode 2 was inserted into the glass tube 1 prior to fusion bonding, the round bar
21 is in a state of being fitted closely to the inner peripheral surface of the electrode 2. Therefore, there is no escape area for nitrogen gas during fusion, and the round bar
A situation occurs in which gas is trapped in the fused portion between 21 and the glass tube 1 (air bubbles of nitrogen gas are taken into the glass), and the portion corresponding to between the round bar portions 21 of the glass tube 1 is shown in FIG. The bent portion 11 as shown is generated and the centers of the electrodes 2 and 2 are deviated from each other, and the appearance of the diode D is spoiled. In addition, insufficient fusion strength due to reduction in fusion area,
Alternatively, there is a problem that a non-sealed portion is generated. Further, there is a problem that cracks may occur in the fusion-bonded portion when it is subjected to thermal shock.

This invention was made in order to solve the problems of the conventional example, the electrode can be reliably fused to the glass tube, as a result the appearance is not impaired, and the lack of fusion strength, non-sealing portion An object of the present invention is to provide a diode that does not cause problems such as occurrence of cracks or cracks.

Means for Solving the Problems In a diode according to the present invention, two electrodes inserted in a glass cylinder in an opposed manner are fused together under an inert gas atmosphere, and a diode chip is sandwiched between both electrodes. In the glass-sealed diode having the fixed structure, a gap for degassing is provided in advance on a part of the inner peripheral surface of the glass cylinder or the outer peripheral surface of the electrode.

When it works, when the glass tube and the electrode are fused, the inner peripheral surface of the glass tube that bulges toward the electrode side discharges the gas to the outside through the gap, so the fused part No gas is trapped in.

Embodiment An embodiment of the present invention will be described below with reference to the drawings. 1 is a longitudinal sectional view of a diode according to the present invention, FIG. 2 (A) is a perspective view of an electrode, and FIG. 2 (B) is a plan view thereof.

In this diode D, the above-mentioned Dumet wire is formed into a round bar shape with a flange. The round bar portions 21 and 21 of the electrodes 2 and 2 are fixed in a glass tube 1 having a circular cross section so as to face each other. The diode chip 3 is sandwiched and fixed between them, and the flange portions 22 of the electrodes 2 and 2 are located outside the glass tube 1 with a slight distance therebetween. The round bar
The outer peripheral surface of 22 is coated with a copper oxide film (not shown) in order to improve the fusion property to the glass tube 1 at the time of fusion bonding described below.

The electrode 2 is fixed to the glass tube 1 by inserting the electrodes 2 and 2 into the glass tube 1 and mounting the glass tube 1 under a pressure condition slightly higher than atmospheric pressure and under an inert gas atmosphere such as nitrogen gas. 1 to soften the glass tube 1
It is performed by fusing the inner peripheral surface of 1 to the outer peripheral surface of the electrode 2.

As shown in FIG. 2, flat portions 23 are formed by notching the outer peripheral surface in the axial direction at appropriate two positions on the outer peripheral surface of the round bar portion 21 so as to face each other. Then, when such a round bar portion 21, that is, the electrode 2 is inserted into the glass tube 1 and attached, a gap between the inner peripheral surface of the glass tube 1 and the outer peripheral surface of the round bar portion 22 at the position where the flat portion 23 is formed is shown in FIG. Since the slight voids 24, 24 as shown in (4) are formed, the gas is discharged to the outside at the time of fusion as described above.

As shown in FIG. 2B, the cutout amount d in the radial direction of the round bar portion 22 may be set to 0.01 mm when the outer diameter of the round bar portion 22 is 0.75 mm. It could be confirmed.

FIG. 4 shows a modification of the electrode 2. In this case, the round bar portion 22 has an elliptical shape and the notch is not provided. That is, the space is formed between the outer peripheral surface of the ellipse in the minor axis direction and the inner peripheral surface of the glass tube 1. This modification eliminates the need for machining.

Although the configuration of the electrode 2 is modified in the above embodiment, the configuration is not limited to this, and the glass tube 1 is not limited to this.
A groove having an appropriate width and an appropriate depth may be formed on the inner peripheral surface of and the voids similar to the above may be formed in the groove forming portion.

Further, although the circular electrode is used as the electrode 2 in the above-mentioned embodiment, a rectangular electrode may be used, and the groove for forming the void may be recessed, and further the electrode 2 connected to the lead wire. May be used.

EFFECTS OF THE INVENTION In the case of the present invention described above, since a gap for allowing gas to escape is provided in the fusion surface of the glass cylinder and the electrode, the fusion portion does not contain gas. Therefore, the appearance of the diode is not impaired, and there are no problems such as insufficient fusion strength, occurrence of non-sealed portions, and occurrence of cracks.

[Brief description of drawings]

1 is a longitudinal sectional view of a diode according to the present invention, FIG. 2 (A) is a perspective view of an electrode, FIG. 2 (B) is a plan view thereof, and FIG. 3 is a sectional view for explaining an air gap, FIG. 4 is a plan view showing a modified example of the electrode. FIG. 5 is a vertical sectional view showing a conventional example. 1 …… Glass cylinder 2 …… Electrode 21 …… Round bar 23 …… Flat part 24 …… Gap 3 …… Diode chip D …… Diode

Claims (1)

[Claims] 1. A glass-sealed diode having a structure in which two electrodes, which are inserted into a glass tube so as to face each other, are fused together in an inert gas atmosphere, and a diode chip is clamped and fixed between the two electrodes. A glass-sealed diode characterized in that a void for degassing is provided in advance in a part of the inner peripheral surface of the glass cylinder or the outer peripheral surface of the electrode.