JP2002303641A - Chip type current detecting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact, high power and high accuracy chip type current detecting element. SOLUTION: The volume resistivity and the thickness of a resistor composed of an alloy plate and the thickness of a copper plate drawn to both ends thereof are controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current sensing element using a material having a copper electrode rolled at both ends of a resistance metal plate, and more particularly to a resistance element using an alloy having a volume resistivity of 1.0 .mu..OMEGA.m or more for a resistor. Body thickness from 0.1mm to 0.5m
By limiting the range to m, a chip-type current detecting element that can be used with a small size and high power can be supplied.

[0002]

2. Description of the Related Art Conventional chip-type current detecting elements include a method of printing a thick film resistor paste on an insulating substrate and a method of attaching a metal foil serving as a resistor and an electrode on the insulating substrate.
In each of these cases, in order to obtain the rated power required for the current detection element to form the resistor and electrode on the insulator serving as the carrier, secure the area of the insulating substrate according to the thickness and heat resistance of the resistor. ing.

In the method of joining a resistance metal plate to the tip of a lead frame serving as an electrode by welding or soldering, a resin mold is used to cover the surface of the lead frame, and the lead frame is processed to form an electrode. ing.

Further, secondary processing such as laser trimming has been required in order to control the resistance value of the element with high accuracy.

[0005]

Among the conventional current detecting elements, a method of printing a thick film resistor paste on an insulating substrate and a method of attaching a metal foil to be a resistor and an electrode on an insulating substrate are known. In order to obtain the rated power required for the device, the area of the insulating substrate must be ensured in accordance with the thickness of the resistor and the heat resistance.

In the method of joining a resistance metal plate to the tip of a lead frame serving as an electrode by welding or soldering, a resin mold is used to cover the surface of the lead frame, and the lead frame is processed to form an electrode. Therefore, there is a restriction on downsizing of parts.

The current detection element has a resistance value accuracy and a detection accuracy of 1
Because of the one-to-one relationship, high accuracy is required for the nominal value. However, in order to control the resistance value of the element with high accuracy, secondary processing such as etching of a resistor or laser trimming is required. Was.

[0008]

According to the present invention, a resistive metal plate having a volume resistivity of not less than 1.0 μΩm is set to 0.1 mm to 0.1 mm.
By using the resistor within a range of 5 mm and adjusting the thickness, width and length of the resistor, a low resistance value can be controlled with high precision.

Further, by adjusting the thickness of the copper electrode to be rolled to both ends, even if resistors having different thicknesses are used, the thickness as an element can be unified, and the mountability is not impaired.

Further, a chip type current detecting element having excellent environmental resistance can be provided by coating the entire circumference of the resistor plate with an insulating material.

The reliability of reflow and flow mounting can be ensured by solder-plating a rolled copper plate on both ends of the resistor.

[0012]

The present invention contributes to miniaturization of equipment and suppression of resistor voltage drop and power consumption in current detection by providing a small, low-resistance, high-precision and high-power chip-type current detection element. .

[0013]

FIG. 1 is a diagram showing an embodiment of the present invention. A resistive element 1 obtained by rolling a nichrome alloy having a volume resistivity of 1.12 μΩm to a thickness of 0.4 mm has a thickness of 0.1 mm on both ends.
A copper plate 2 serving as a 2 mm electrode was rolled. In this case, the element thickness is 0.6 mm. The total length of the element is 6.3 mm, the length of the resistor is 3.7 mm, and the electrode width at both ends is 1.3.
mm. This metal plate has a width of 2.4 mm to 3.3 mm.
From 3.3 mΩ to 5.6 mΩ by cutting in the range of
Was obtained.

FIG. 2 is a diagram showing an embodiment of the present invention. 0.5 mm thick on both ends of a resistor 1 obtained by rolling a nichrome alloy having a volume resistivity of 1.12 μΩm to a thickness of 0.1 mm.
Was rolled. In this case, the element thickness is 0.6 mm. The total length of the element was 6.3 mm, the length of the resistor was 5.3 mm, and the electrode width at both ends was 0.5 mm. By cutting this metal plate in the range of 2.7 mm to 3.3 mm in width, an element of 18 mΩ to 22 mΩ was obtained.

FIG. 3 is a diagram showing an embodiment of the present invention. The entire circumference of the resistor 1 rolled to a thickness of 0.1 mm is covered with a protective film 3, and the surface of the copper plate 2 serving as an electrode is plated with solder 4.
Covered.

As is clear from the above-described embodiment, according to the present invention, in a current detecting element using a material having a rolled copper electrode at both ends of a resistance metal plate, particularly, the resistor has a volume resistivity of 1. By using an alloy having a resistance of 0 μΩm or more and limiting the thickness of the resistor within the range of 0.1 mm to 0.5 mm, a small-sized chip-type current detection element that can be used with high power can be supplied.

[0017]

As described above, according to the present invention, a material having rolled copper electrodes at both ends of a resistance metal plate having a volume resistivity of 1.0 μΩm or more is used, and the thickness of the resistor is 0.1 m.
If the length is at least m, the mechanical strength of the chip component can be ensured. Further, by using the resistor thickness up to 0.5 mm, it is possible to manufacture 1 mΩ, which is the lowest resistance value of the current detection element currently used, in a small chip shape. By controlling the thickness of the resistor in the range of 0.1 mm to 0.5 mm, 1 m which is the normal resistance value range of the current detection element is obtained.
It is possible to manufacture a small-sized, high-precision, high-power chip-type current detecting element with a resistance of Ω to 50 mΩ.

A common resistance value range required for the current detecting element is to use resistors having different thicknesses in order to manufacture 1 mΩ to 50 mΩ. However, the thickness of the copper plate rolled on both ends of the resistor depends on the thickness of the resistor. By changing, the thickness of the element can be unified.

Further, by protecting and coating the entire periphery of the resistor plate with an insulating material, it is possible to provide a chip type current detecting element having excellent environmental resistance.

[Brief description of the drawings]

FIG. 1 shows a current detecting element according to the present invention in which a resistor thickness is 0.4 mm, an electrode thickness is 0.2 mm, and an element thickness is 0.6.
It is explanatory drawing of the current detection element which becomes mm.

FIG. 2 shows a current detection element according to the present invention in which a resistor thickness is 0.1 mm, an electrode thickness is 0.5 mm, and an element thickness is 0.6.
It is explanatory drawing of the current detection element which becomes mm.

FIG. 3 is an explanatory view of a current detecting element in which a whole periphery of a resistor 1 is covered with a protective film 3 and a surface of a copper plate 2 serving as an electrode is covered with a solder plating 4 in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Resistor 2 Electrode 3 Protective film 4 Solder plating

Claims (3)

[Claims] 1. A chip-type current detecting element in which the thickness of a resistor is controlled in a range of 0.1 mm to 0.5 mm using a material having a copper electrode rolled on both ends of a resistance metal plate having a volume resistivity of 1.0 μΩm or more. 2. A chip-type current detecting element according to claim 1, wherein when two or more kinds of resistance metal plates are used, the total thickness of the resistance metal plate and the thickness of the copper to be rolled is equal. 3. A chip-type current detecting element according to claim 1, wherein the entire periphery of the resistor plate is protectively coated with an insulating material, and electrodes at both ends are solder-plated.