JP2000048696A - Thermal fuse - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal fuse not to be easily fused by heat in soldering. SOLUTION: This thermal fuse has a fuse element 14c composed of two lead wires 11, a fusible alloy 12 connected between these two lead wires 11 and flux 13 applied on the fusible alloy 12 or the vicinity of the connecting part of the fusible alloy 12 and the two lead wires 11, a cylindrical case 15 to store the fuse element 14 so as to protrude the two lead wires 11 outside from an opening part, and a sealing agent 16 to seal the opening part of the cylindrical case 15, and the two lead wires 11 are composed by applying Ni plating and metal plating having a low fusing point around a Fe wire or an alloy wire containing Fe.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-return type thermal fuse for protecting a set and an electronic component from overheating, and more particularly to a thermal fuse for solder heat resistance.

[0002]

2. Description of the Related Art As a conventional thermal fuse for solder heat resistance, there is known a thermal fuse as disclosed in JP-A-7-226139.

[0003] A conventional thermal fuse for measures against soldering heat will be described below with reference to the drawings.

FIG. 5 is a side view of a conventional thermal fuse for solder heat resistance. FIG. 6 is a sectional view taken along line BB 'of FIG. In FIG. 5, reference numeral 1 denotes a fuse element (not shown);
This is a cylindrical case in which the lead wires 2 are housed so as to protrude outside through the opening, and the opening of the cylindrical case 1 is sealed with a sealant 3. As shown in FIG. 6, the two lead wires 2 are Fe wires 4 having low heat conduction as core wires and hardly transmitting heat of the solder to the temperature fuse body at the time of soldering. And then Sn plating 6 around the Cu plating 5
Has been applied.

[0005]

However, in the above-described conventional thermal fuse, since the two lead wires 2 are formed by plating the Fe wire 4 around the Cu plating 5, the thermal fuse is not used. At the time of soldering, when the solder temperature is high, when the soldering time is long, or when the length of the lead wire 2 from the temperature fuse body of the thermal fuse to be soldered to the soldering part is short, the heat of the solder is reduced. There is a problem in that the thermal fuse is transmitted to the thermal fuse body via the Cu plating 5 having good thermal conductivity, and the thermal fuse is blown.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a thermal fuse that is not easily blown by heat during soldering.

[0007]

In order to achieve the above object, a thermal fuse according to the present invention comprises two leads, a fusible alloy connected between the two leads, and the fusible alloy or the fusible alloy. A fuse element composed of a molten alloy and a flux applied in the vicinity of a connection portion between the two lead wires; and a cylindrical shape for housing the fuse element such that the two lead wires protrude outside through the opening. A case and a sealant for sealing an opening of the cylindrical case, wherein the two lead wires are Ni-plated around an Fe wire or an alloy wire containing Fe,
This is configured by sequentially applying low-melting metal plating, and according to this configuration, it is possible to provide a thermal fuse that is not easily blown by heat during soldering.

[0008]

DETAILED DESCRIPTION OF THE INVENTION According to the first aspect of the present invention, there are provided two lead wires, a fusible alloy connected between the two lead wires, and a fusible alloy or a fusible alloy. A fuse element composed of a flux applied in the vicinity of the connection part of the two lead wires; a cylindrical case for housing the fuse element such that the two lead wires project outside through the opening; A sealant for sealing the opening of the cylindrical case, wherein the two lead wires are formed by sequentially applying Ni plating and low melting point metal plating around an Fe wire or an alloy wire containing Fe. According to this configuration, N
Since the heat conduction of i is sufficiently lower than the heat conduction of Cu, when the soldering for attaching the thermal fuse is performed, when the solder temperature is high, when the soldering time is long, or when the thermal fuse to be soldered is used. Even when the length of the lead wire from the lead to the soldering portion is short, it has the effect of not easily fusing at the time of soldering.

According to a second aspect of the present invention, there are provided two lead wires, a fusible alloy connected between the two lead wires, and a connecting portion between the fusible alloy or the fusible alloy and the two lead wires. A fuse element composed of a flux applied to the vicinity, a cylindrical case for housing the fuse element such that two lead wires protrude outside from the opening, and an opening of the cylindrical case And a sealant for sealing, the two lead wires are formed by sequentially applying Ni plating and low melting point metal plating around an alloy wire containing Cu,
According to this configuration, for example, the heat conduction of an alloy wire containing Cu, such as an alloy wire of Cu and Zn, is lower than that of a Cu wire used for a normal thermal fuse that does not take measures against heat during soldering. Therefore, when the soldering temperature is high, the soldering time is long, or
Even if the length of the lead wire from the thermal fuse body to the soldering portion in the thermal fuse to be soldered is short, the thermal fuse does not easily blow at the time of soldering.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view showing the internal structure of the thermal fuse according to Embodiment 1 of the present invention, and FIG. 2 is a sectional view taken along line AA 'of FIG. As shown in FIG. 1, the thermal fuse according to the first embodiment of the present invention
A fusible alloy 12 is connected between the two lead wires 11, and a flux 13 is applied to all of the fusible alloy 12 or the vicinity of a connection portion between the fusible alloy 12 and the two lead wires 11 to form a fuse element 14. And the fuse element 14
The two lead wires 11 are housed in a cylindrical case 15 made of ceramic or resin and having both ends opened so that the two lead wires 11 project outside from the opening, and the opening of the cylindrical case 15 is epoxy-based. It is configured by sealing with a sealing agent 16 made of a synthetic resin or the like. And the lead wire 1
2, as shown in FIG. 2, a Fe wire or an alloy wire 17 containing Fe is used as a core wire, Ni plating 18 is applied around the Fe wire, and S
It has a configuration in which low melting point metal plating 19 such as n, Ag, and solder is applied.

FIG. 3 is a longitudinal sectional view showing the internal structure of the thermal fuse according to the second embodiment of the present invention. In the thermal fuse according to the second embodiment of the present invention, a fusible alloy 22 is connected between two lead wires 21 as shown in FIG.
Then, all of the fusible alloys 22 or the fusible alloys 22 and 2
A flux 23 is applied to the vicinity of the connection portion of the two lead wires 21 to form a fuse element 24, and the fuse element 24 is provided in a bottomed cylindrical case 25 made of ceramic or resin and having one end opened. The lead wire 21 is housed so as to protrude outside from the opening, and the opening of the cylindrical case 25 with a bottom is further sealed with a sealant 26 made of an epoxy-based synthetic resin or the like. I have. As the lead wire 21, similarly to the lead wire 11 in the first embodiment of the present invention, a Fe wire or an alloy wire 17 containing Fe is used as a core wire, and Ni plating 18 is applied around the periphery thereof,
In addition, Sn,
The configuration is such that a low melting point metal plating 19 such as Ag or solder is applied.

The intermediate plating layers of the lead wires 11 and 21 used in the first and second embodiments of the present invention are made of Ni plating 18, and the thermal conductivity of Ni in the Ni plating 18 is 94W. · M ^-1 · K ^-1, which is sufficiently lower than the conventionally used thermal conductivity of Cu of 400 W · m ^-1 · K ^-1. In the case where the soldering time is long or the length of the lead wires 11 and 21 from the thermal fuse body to the soldering portion in the thermal fuse to be soldered is short, the heat of the solder is reduced as in the conventional case. , 21 through the fusible alloy 12, 22
And the thermal fuse is not blown.

Table 1 shows lead wires 2 projecting from the thermal fuse body in the thermal fuse having the structure shown in FIG.
5 shows test data obtained by measuring the limit time at which a temperature fuse that melts at 130 ° C. does not melt when a portion up to a length of 5 mm in FIG. 1 is immersed in a 300 ° C. molten solder bath. In this (Table 1), a is a temperature fuse of the present invention using a lead wire which is sequentially plated with Ni and Sn plating on an Fe wire, b is Cu plating on an Fe wire,
A conventional temperature fuse for solder heat resistance using lead wires successively plated with Sn, and c is a conventional temperature fuse for Cu wire which is not subjected to solder heat resistance and plated with Sn.

[0014]

[Table 1]

As is clear from Table 1, c is 1 second,
b was not endurable for 3 seconds, but a, which is the thermal fuse of the present invention, could endure for 13 seconds without fusing.

FIG. 4 is a sectional view of a lead wire of a thermal fuse according to a third embodiment of the present invention. This lead wire 31 contains, for example, Cu as a core wire such as an alloy wire of Cu and Zn. Using an alloy wire 32, a Ni plating 33 is applied to the periphery thereof, and a low melting point metal plating 3 of Sn, Ag, solder, etc.
4 is applied.

Thermal conductivity of Cu and Zn alloy wire as core wire
Is 105W · m^-1・ K^-1And the thermal conductivity of the Fe wire is 9
0W ・ m^-1・ K^-1Similarly, the thermal conductivity of the Cu wire is 400 W
・ M ^-1・ K^-1Is sufficiently lower than
When soldering, when soldering temperature is high
If the soldering time is long,
From the body of the thermal fuse
Even if the length of the lead wire 31 to the attachment part is short,
The fuse will no longer melt easily
It is.

[0018]

As described above, the thermal fuse of the present invention has the following features.
A fuse composed of two lead wires, a fusible alloy connected between the two lead wires, and a flux applied near the connection between the fusible alloy or the fusible alloy and the two lead wires. An element, a cylindrical case for housing the fuse element such that the two lead wires protrude outside from the opening, and a sealant for sealing the opening of the cylindrical case, The two lead wires are formed by sequentially applying Ni plating and a low-melting metal plating around an Fe wire or an alloy wire containing Fe. According to this configuration, the intermediate layer of the lead wire has a smaller thickness than Cu. Since Ni plating with low thermal conductivity is applied, when soldering to attach a thermal fuse, if the solder temperature is high, if the soldering time is long, or if the thermal fuse in the thermal fuse to be soldered Even if the length of the lead wire to Rahanda mounting portion is short and has an excellent effect that it is possible to provide a thermal fuse which does not easily blown during soldering. Furthermore, since the heat absorbed by the thermal fuse body is less likely to be dissipated from the lead wire by employing the above-described lead wire, the absorbed heat can be efficiently transmitted to the fuse element, and as a result, a temperature with good thermal responsiveness can be obtained. A fuse can be provided.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an internal structure of a thermal fuse according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA 'of FIG.

FIG. 3 is a longitudinal sectional view showing an internal structure of a thermal fuse according to a second embodiment of the present invention.

FIG. 4 is a sectional view of a lead wire of a thermal fuse according to a third embodiment of the present invention.

FIG. 5 is a side view of a conventional thermal fuse for solder heat resistance.

FIG. 6 is a sectional view taken along line BB ′ of FIG. 5;

[Explanation of symbols]

 11, 21 Lead wire 12, 22 Soluble alloy 13, 23 Flux 14, 24 Fuse element 15, 25 Case 16, 26 Sealant 17 Fe wire or alloy wire containing Fe 18 Ni plating 19 Low melting point metal plating 31 Lead wire 32 Alloy wire containing Cu 33 Ni plating 34 Low melting point metal plating

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Atsushi Kono 1006 Kadoma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. F-term (reference) 5G502 AA02 BA03 BB10 BC02

Claims (2)

[Claims] The present invention relates to two lead wires, a fusible alloy connected between the two lead wires, and a flux applied near a joint between the fusible alloy or the fusible alloy and the two lead wires. Element, a cylindrical case for accommodating the fuse element such that two lead wires protrude outside from the opening, and a sealant for sealing the opening of the cylindrical case A thermal fuse comprising two lead wires, which are sequentially plated with Ni plating and low-melting metal plating around an Fe wire or an alloy wire containing Fe. 2. A method according to claim 1, wherein the two lead wires, a fusible alloy connected between the two lead wires, and a flux applied near a connection between the fusible alloy or the fusible alloy and the two lead wires. Element, a cylindrical case for accommodating the fuse element such that two lead wires protrude outside from the opening, and a sealant for sealing the opening of the cylindrical case And a thermal fuse comprising the two lead wires formed by sequentially applying Ni plating and low melting point metal plating around an alloy wire containing Cu.