JP2001291601A - Low-value resistor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-value resistor with an electrode structure of sufficiently high mechanically bonding strength and superior in uniformity of a current distribution. SOLUTION: Metal thin pieces 12 and 13 are bonded as electrodes to a resistor 11 of a metallic material by rolling or thermal diffusion for the formation of a low-value resistor. Or a molten solder layer may be provided as an electrode to the resistor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low resistor having a structure in which electrodes are provided at both ends of a metal material.

[0002]

2. Description of the Related Art A low resistor having electrodes at both ends of a plate-shaped or ribbon-shaped metal material is widely used as a current detecting resistor and the like because of its good heat dissipation and large current capacity. . As the metal material as the resistor, for example, a copper-nickel-based alloy, a nichrome-based alloy, an iron-chromium-based alloy, a manganin-based alloy, or the like is used, and electrodes are provided at both ends of the metal material. As a conventional electrode structure, a plating electrode is generally formed on the above-described metal material.

However, in the case of such a plated electrode, it is difficult to form a thick plated layer, so that the same potential in the electrode is weak, the current path is not stable, and a highly accurate resistor is formed. There is a problem to make. In addition, there is a problem that the electrode formed by plating has a weak bonding property with a metal material serving as a resistor, and is weak to mechanical stress, thermal stress, and electric stress when the metal material serving as a resistor is bent and used. I do.

In some cases, a thin plate made of copper or nickel is fixed by electron beam welding or the like in place of a plated electrode to form an electrode. Even in such a case, the metal flakes joined by spot welding have a small joint area at the welding point, and similarly have a problem in joint strength and uniformity of electric current distribution.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a low resistor having an electrode structure which has mechanically sufficient bonding strength and excellent current distribution uniformity. Aim.

[0006]

According to a first aspect of the present invention, there is provided a resistor made of a metal material, wherein a rolled or heat diffusion bonded metal flake is provided as an electrode of the resistor. It is a low resistor.

In this low-resistance device, thin metal flakes are bonded to both ends of a resistor made of a metal material by rolling or heat diffusion bonding. The metal flake bonded by rolling or thermal diffusion bonding as described above has a diffusion layer existing at the interface of the metal material constituting the resistor or at the inside thereof, as compared with plating or welding. Therefore, due to the presence of the diffusion layer, high bonding strength can be obtained and uniformity of electric current distribution can be obtained. Therefore, an electrode structure of a low-resistance resistor that is stable against mechanical stress, thermal stress, electrical stress, and the like can be obtained.

According to a second aspect of the present invention, there is provided a low resistor comprising a resistor made of a metal material and a molten solder layer provided as an electrode of the resistor.

The molten solder layer is an extremely thin solder layer having a thickness of about several microns on the surface, but is formed by diffusing the solder layer into a metal material serving as a resistor which is a base material. For this reason, due to the presence of the solder layer diffused into the inside, high bonding strength can be obtained and uniformity of electric current distribution can be obtained. Accordingly, an electrode structure of a low resistor that is similarly stable against mechanical stress, thermal stress, electrical stress, and the like can be obtained.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 (a) (b)
3 shows a structural example of the low resistor according to the first embodiment of the present invention. Metal material (base material) 1 constituting a resistor as shown in the figure
1 are provided with metal flakes 12 and 13 joined to both ends by rolling or heat diffusion bonding. Here, metal flake 1
Reference numerals 2 and 13 have a so-called inlay clad structure, which is a structure embedded in the base metal material 11. Here, the base metal is preferably a copper-nickel alloy, a nichrome alloy, or an iron-chromium alloy. As the metal flake to be joined by rolling or thermal diffusion joining, a thin plate of copper or nickel having a thickness of about 50 to 200 μm is used.

The low resistor has a length (development length) of about 20 mm or less, a width of about 5 mm, and a joint between the rolled metal flakes of about 2.5 mm from both ends. . The thickness of the base material is 150 to 6
It is about 00 μm. Thereby, the resistance value is, for example, several m.
A low resistance value of about Ω to several tens mΩ can be obtained. Incidentally, in the case of this embodiment, a so-called inlay clad structure in which a metal sheet to be rolled or thermally diffusion-bonded is embedded in a base material, but a metal thin piece is placed on a flat base material and May be so-called top lay clad structure joined by rolling or heat diffusion bonding.

A low resistor having such a structure is formed by first preparing a metal material serving as a base material, and joining a thin metal plate to both sides of the metal material serving as the base material by rolling or heat diffusion bonding. I do. Rolling or thermal diffusion bonding is performed by applying pressure while applying a predetermined temperature. As a result, a diffusion layer of the metal flake material is formed on or at the joint surface of the base material. Then, it is cut to a predetermined size, and FIG.
It is formed by bending into a shape as shown in (a) or (b). In the case of the buried structure (inlay clad structure), it is necessary to previously provide a groove for the buried portion in the base material.

The low-resistance resistor manufactured as described above has a sufficient mechanical strength at the electrode portion joined by rolling or thermal diffusion bonding when working in a bent shape as shown in FIGS. 1 (a) and 1 (b). Since it has strength, there is no problem of cracking or peeling of the electrode during processing. In addition, since the completed low resistor has good uniformity of current distribution of its electrode, good electrical characteristics of the low resistor can be obtained. Also, when mounting this resistor on a printed circuit board, since it has excellent mechanical strength, thermal strength, and electrical strength, it is possible to mount it stably against these various stresses. The change with time can be kept small.

FIGS. 2A and 2B show an example of the structure of a low resistor according to a second embodiment of the present invention. The metal material serving as the base material of the low resistor is substantially the same as that of the first embodiment, and a copper-nickel alloy, a nichrome alloy, a manganin alloy, or the like is used. Further, electrodes 15 and 16 made of a molten solder layer are provided at both ends of the metal material 11 serving as a resistor. The electrode made of the molten solder layer is formed by diffusing the solder layer into a metal serving as a base material, and has a thickness on the surface of only a few μm. Such a molten solder layer has excellent mechanical strength and current stability because the solder diffusion layer exists at the interface with and inside the metal base material as compared with the conventional electrode structure such as plating or welding. I have.

Although the thickness is only about several μm, it has a feature that it has sufficient strength for bending and that the electric resistance is extremely small due to the diffused molten solder layer. Furthermore, it is expected that the temperature coefficient of resistance (TCR) characteristics will be better as compared with a conventional electrode structure formed by welding a thin copper plate or formed by plating. For example, while the change in resistance during a certain period of the plating electrode is about 0.5 to 2.0%, the change in resistance is 0 to 0 when a molten solder layer is used.
It is greatly reduced to 0.1%. Also, the temperature coefficient of resistance (TC
R), the TCR of the copper material is 4000 to 5000 pp
On the other hand, when the molten solder layer is used, it is about 2000 ppm / ° C.

Further, by using an electrode using a molten solder layer, it is possible to easily cope with solder connection without using lead. That is, when mounting on a printed circuit board or the like, various solder materials can be used, and mounting using a lead-free solder material is possible. As a result, an electrode structure having excellent compatibility with environmental problems can be obtained.

The above-described examples of the shape and dimensions of the low resistor are merely examples, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.

[0018]

As described above, according to the present invention, it is possible to provide a low resistor having an electrode structure having good electrical characteristics and sufficient mechanical strength.

[Brief description of the drawings]

FIGS. 1A and 1B are perspective views showing a low resistor according to a first embodiment of the present invention.

FIGS. 2A and 2B are perspective views showing a low resistor according to a second embodiment of the present invention.

[Explanation of symbols]

11 Metal material (base material) to be a resistor 12, 13 Electrode formed by rolling or heat diffusion bonding of thin metal plate 15, 16 Electrode formed by molten solder layer

Claims (2)

[Claims] 1. A low-resistance device comprising a resistor made of a metal material and a rolled or heat-diffused metal flake as an electrode of the resistor. 2. A low-resistance device comprising a resistor made of a metal material and a molten solder layer provided as an electrode of the resistor.