JP3284375B2 - Current detecting resistor and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current detecting resistor and a method of manufacturing the same, and more particularly, to a current detecting resistor for passing a current of about several tens A and detecting a voltage of about several tens mV with high precision and low resistance. The present invention relates to a resistor and a method for manufacturing the resistor.

[0002]

2. Description of the Related Art A current detecting resistor for a vehicle or the like has a low resistance of about several tens of amperes and detects a voltage of about several tens of mV, and the accuracy of the resistance value variation is, for example, 1%. In some cases, high accuracy within the range is required. Conventionally, a large-sized two-terminal standard resistor has been used for such a resistor requiring low resistance and high accuracy.

However, it is not easy to control the resistance value of a two-terminal resistor by trimming with such a low resistance value of about 1 mΩ and a variation accuracy of about 1%. The contact resistance was larger than 1 mΩ of the object to be measured, and it was difficult to perform even the measurement with high accuracy.

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, the present invention provides a current of about several tens of A and a current of several tens of mV.
It is an object of the present invention to provide a high-precision current detecting resistor which can detect a voltage of about the same level and can manufacture the resistance value with less variation (for example, within 1%), and a method of manufacturing the same. I do. At the same time, another object of the present invention is to provide a current detection resistor that is small and has good heat dissipation, and that can be surface-mounted on a printed circuit board or the like, and a method of manufacturing the same.

[0005]

SUMMARY OF THE INVENTION A current detecting resistor according to the present invention includes a low-resistance metal resistor having a pair of current terminals and a pair of voltage terminals, and sandwiches the metal resistor in a sandwich shape. Or an insulating member to be embedded, wherein the current terminal and the voltage terminal are bent so as to be surface mountable, and the metal resistor is formed by monitoring a voltage between the voltage terminals generated by a current flowing between the current terminals. The resistance value is trimmed and adjusted.

In the method of manufacturing a current detecting resistor according to the present invention, a metal resistor having a pair of current terminals and a pair of voltage terminals as a plurality of units is connected to each other via the current terminals. Forming a series of resistor groups as described above, and flowing a current between current terminals at both ends of the series of resistor groups, and monitoring the voltage generated between the voltage terminals of the resistors serving as units, thereby monitoring the resistance value. A step of trimming and adjusting a resistor as a unit sequentially, a step of separating the resistor as a unit from a series of resistor groups and sandwiching or embedding it in an insulating member, and surface mounting the current terminal and the voltage terminal of each resistor. Bending as much as possible.

[0007]

A plurality of metal resistors form a series of resistor groups connected to each other through their current terminals, and a current flows between current terminals at both ends of the series of resistor groups. The resistance value of each unit resistor can be trimmed while monitoring the voltage generated between the voltage terminals of the unit resistor. Therefore, without being affected by contact resistance,
Since the resistance value of each resistor can be measured, a high-precision low resistor can be efficiently manufactured. In addition, the resistor that has been trimmed and adjusted with high precision is separated from a series of resistor groups, and sandwiched or embedded in an insulating member.
By bending the current terminal and the voltage terminal of each resistor so that they can be surface-mounted, it is possible to manufacture a small current detection resistor that has excellent heat dissipation characteristics and can be surface-mounted on a printed circuit board or the like.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows the structure of a current detecting resistor according to a first embodiment of the present invention. FIG.
(B) is a side view. As shown in the figure, the current detecting resistor 1 includes a pair of current terminals 5 and 6 and a pair of voltage terminals 7 and 8.
Is sandwiched between the ceramic substrates 3 in a sandwich shape. The size of the ceramic substrate 3 is about 10 mm in width and about 5 mm in length in the present embodiment, and is small enough to be surface-mounted on a printed circuit board. The current terminals 5, 6 and the voltage terminals 7, 8 are bent into a U-shape so that they can be surface-mounted.

FIG. 2 is a plan view of the metal resistor 2. The metal resistor 2 includes current terminals 5 and 6 and voltage terminals 7 and 8, and detects a voltage generated by a current flowing between the pair of current terminals 5 and 6 with the pair of voltage terminals 7 and 8. . And it is manufactured by performing trimming adjustment of the metal resistor 2 while monitoring the voltage between the voltage terminals 7 and 8. The opening 9 is an opening formed by high-precision trimming by laser trimming or spraying such as sandblasting. As described above, since the current detector detects the voltage generated by the resistor of the current flowing between the current terminals 5 and 6 at the voltage terminals 7 and 8, the current detector is not affected by the contact resistance and performs high-precision current detection. be able to.

The operation of such a current detecting resistor is as follows. First, for example, when used for a vehicle-mounted temperature sensor, the current detection resistor 1 is surface-mounted on a printed circuit board. Then, a current to be detected is applied between the current terminals 5 and 6. And between the voltage terminals 7 and 8
A voltage value is detected according to the trimmed resistance value of the metal resistor 2. Therefore, by monitoring the voltage between the voltage terminals 7 and 8, the magnitude of the current flowing through the current terminals 5 and 6 can be detected. As an example, when the resistance value of the metal resistor is about 1 mΩ, a voltage of about several tens mV is detected when a current of several tens A flows. According to this structure, since the measurement is performed by the four-terminal method, a large current can be accurately measured with low resistance without being affected by contact resistance. In such a case, about 2 W of heat is generated. However, since the metal resistor 2 is sandwiched between the ceramic substrates 3, the heat dissipation is good, and the temperature rise is suppressed. Can be.

Next, a method for manufacturing the current detecting resistor according to the present invention will be described. First, an electric resistance alloy special plate serving as a base of the low resistance metal resistor 2 is prepared. These are copper-nickel, manganin, geranin, iron-copper,
It is an alloy plate of various metals such as a nichrome plate. And FIG.
A series of resistor groups 10 shown in (A) are formed by etching using a film mask or press punching using a die. Then, the current terminals 5, 6 and the voltage terminals 7, 8 are plated with solder. This is a partial plating process by masking.

FIG. 3 is a plan view of a series of resistor groups.
(A) is before resistance trimming, and (B) is after resistance trimming. The series resistor group 10 includes a plurality of metal resistors 2 each having a pair of current terminals and a pair of voltage terminals, which are connected to each other via the current terminals 5 and 6. A current of, for example, about 5 A is passed between the current terminals 15 and 16 at both ends of the series of resistor groups 10 to adjust the trimming of the metal resistor 11 while monitoring the voltage between the voltage terminals 7 and 8 of each metal resistor. Is performed to form an opening 12. Next, the trimming adjustment of the metal resistor 13 is performed in the same manner, and the opening 14 is similarly formed. The resistance value of each metal resistor is adjusted with high precision by sequentially performing trimming adjustment of the metal resistors as a unit in this order.

The trimming is performed by laser trimming, sand blast, diamond cutter, grinder cutter or the like. Next, the series of resistor groups 10 are cut into resistor units. Then, a ceramic substrate made of alumina or the like is attached to the resistor 2 serving as a discrete unit by using an adhesive to form a sandwich. Then, the terminals 5, 6, 7, and 8 are formed, that is, bent, and the current detecting resistor 1 is assembled. Then, an insulating material such as a mold and a resin dip is sealed between ceramic substrates sandwiching the metal resistor to finish the exterior. For example, the metal resistor 2 is sandwiched between the alumina substrates 3 and bonded with silicon rubber. Then, characteristics such as appearance and resistance are inspected to complete the current detection resistor 1.

FIG. 4 shows the structure of a current detecting resistor according to a second embodiment of the present invention, wherein FIG.
(B) and (C) are side views. Current terminal 25,
The structure in which the low-resistance metal resistor 22 provided with 26 and voltage terminals 27 and 28 is sandwiched between ceramic substrates 23 in the same manner as in the first embodiment. The difference from the first embodiment is that the current terminals 25, 26 and the voltage terminals 27,
Reference numeral 28 denotes a point which is bent and extended along the ceramic substrate 23. As described above, since the current terminals 25 and 26 and the voltage terminals 27 and 28 are bent and extended, surface mounting on a printed circuit board or the like becomes possible as in the first embodiment.

FIG. 5 is a plan view of a metal resistor 22 according to the second embodiment. This metal resistor 22 is provided with an opening 29 by resistance trimming as in the first embodiment. The pattern of the metal resistor 22 is the first
Although it is different from the embodiment, it is appropriately selected according to the current capacity, the set resistance value and the like. Although the insulating members 3 and 23 are described as ceramic substrates in the first and second embodiments, they may be molded with a plastic (for example, silicone resin) containing a thermally conductive filler. Good. As described above, the material of the insulating members 3 and 23 and the sealing method can be appropriately selected according to the use of the current detecting resistor.

FIG. 6 shows a plane view of a series of resistor groups 20 in which a plurality of units of a metal resistor 2 having a pair of current terminals and a pair of voltage terminals are connected to each other via the current terminals. FIG. (A) is before resistance trimming,
(B) is after the opening 29 is provided by resistance trimming. These are different from the first embodiment only in the shape and the number of metal resistors as a unit, and the functions are the same. By increasing the size of the metal resistor, the current capacity can be increased to the order of 90A.

[0017]

As described above, according to the current detector of the present invention, it is possible to accurately detect a large current of about several tens A with a small voltage of about several tens mV without being affected by contact resistance. Can be. Thus, a current detector that is compact, surface-mountable, and has good heat dissipation is realized. Further, according to the method of manufacturing the current detector of the present invention, the trimming adjustment is performed for each metal resistor as a unit while applying a current to the entire series of metal resistors, so that the accuracy can be reduced by ± 1 even though the resistance is low. %, And production can be efficiently performed.

[Brief description of the drawings]

FIG. 1A is a plan view and FIG. 1B is a side view showing the structure of a current detection resistor according to a first embodiment of the present invention.

FIG. 2 is a plan view of a metal resistor which is a unit of the first embodiment of the present invention.

FIGS. 3A and 3B are plan views of a series of resistor groups composed of a plurality of metal resistors according to the first embodiment of the present invention, wherein FIG. 3A shows a state before resistor trimming and FIG. .

4A is a plan view, FIG. 4B is a side view, and FIG. 4C is a side view showing the structure of a current detecting resistor according to a second embodiment of the present invention.

FIG. 5 is a plan view of a metal resistor which is a unit of a second embodiment of the present invention.

FIGS. 6A and 6B are plan views of a series of resistor groups according to a second embodiment of the present invention, in which FIG. 6A shows a state before resistance trimming and FIG. 6B shows a state after resistance trimming.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Current detection resistor 2,11,13,22 Metal resistor 3,23 Insulating member 5,6,15,16,25,26 Current terminal 7,8,27,28 Voltage terminal 9,12,14 Opening 10 , 20 series of metal resistor groups

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01C 1/00-17/30

Claims (2)

(57) [Claims] 1. A low-resistance metal resistor having a pair of current terminals and a pair of voltage terminals, and an insulating member sandwiching or embedding the metal resistor in a sandwich shape, wherein the current terminal and the voltage terminal are provided. Is bent so as to be surface mountable, and the resistance of the metal resistor is trimmed and adjusted by monitoring a voltage between the voltage terminals generated by a current flowing between the current terminals. Current detection resistor. 2. A pair of current terminals and a plurality of units,
A step of forming a series of resistors connected to each other through the current terminals by a metal resistor having a pair of voltage terminals; and flowing a current between current terminals at both ends of the series of resistors. A step of sequentially trimming and adjusting the resistance value by monitoring a voltage generated between the voltage terminals of the unit resistors, and a step of separating each unit resistor from a series of resistor groups and inserting or embedding it in an insulating member. Bending a current terminal and a voltage terminal of each resistor so as to be surface mountable.