JPH06275402A - Chip resistor, and method and circuit for detection of current - Google Patents

Abstract

PURPOSE:To provide a chip resistor suitable for a sensor for detecting current. CONSTITUTION:A chip resistor comprises a resistance element 3 on substrate 2, and a pair of branch terminals 4a and 4b are extended from each end of the resistance element. When this chip resistor is used for a current sensor, the branch terminals 4a are used as current terminals while the branch terminals 4b are used as voltage terminals.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip resistor, and a current detection circuit and a current detection method using the same, which are adapted to be incorporated as a current detection sensor in a protection circuit of a DC / DC converter. Regarding things.

[0002]

2. Description of the Related Art DC to be Solved by the Invention
In some cases, a resistor is incorporated as a current detection sensor portion in the protection circuit of the / DC converter, and a chip resistor is often used as such a resistor because of the demand for higher circuit integration.

Since the above chip resistor is a current sensor, it is required to have a low resistance value of, for example, about 0.1Ω.

By the way, the chip resistor is formed on the assumption that it is surface-mounted on a circuit board. Generally, as shown in FIGS. 9 and 10, a chip substrate a having a rectangular shape in plan view and having a predetermined thickness is used. A resistor b is formed by thick film printing on the upper side, and electrode terminals c, c are formed on both ends of the resistor b.
It is basically configured by forming.

As a measure for lowering the resistance value of the resistor b, there is a method of shortening the distance between the electrode terminals of the resistor b as shown in FIG. 11, and as shown in FIG. There is a method of using the same conductor pattern as that for forming the electrode terminals at both ends and reducing the width dimension thereof.

In any case, the conventional chip resistor is
Regardless of the resistance value, the resistor b or the resistor portion is arranged in the central portion on the chip substrate,
Electrode terminals c, c are formed on both ends of the chip substrate so as to sandwich the chip, and the resistor b and the electrode terminals c, c are formed.
Has a basic structure in which a part of the is covered with the protective coating d.

By the way, in the case of constructing a chip resistor having a low resistance value as described above, it is often difficult to adjust the interelectrode resistance value within a predetermined range. The reason is as follows.

Resistance value of the chip resistor having the above configuration
Is, for example, the equivalent circuit when measuring by the four-terminal method is
It becomes like FIG. In FIG. 13, R₁Is the resistor part
Resistance of R₂And R₃Is inside the electrode terminal
It represents resistance. Resistance value R of the resistor part₁Is small
In addition, the internal resistance R of the electrode terminals on both sides of it₂, R
₃Will be affected.

When the resistance value of the chip resistor is measured, as shown in FIG. 13, a constant current is passed between the electrodes c and c while the voltage measuring probes p and p are simultaneously applied to the electrodes.
The voltage drop between both electrodes is measured by applying p, etc., and the above R ₁ , R ₂ , R ₃ are calculated by Ohm's formula.
The sum of the resistance values of is calculated.

However, in particular, since the electrode terminals c, c are also formed by the thick film printing method, the values of the internal resistances R ₁ , R ₃ of the electrode terminals are different depending on the manufacturing conditions of the chip resistor, and therefore , R ₁ , R ₂ , R _{3 above}
It becomes difficult to make the resistance value of the chip resistor as a whole, which is given by the sum of,

As a result, when the allowable error range with respect to the required rated resistance value is small, the yield is reduced. The resistance value of the type shown in FIG. 11 can be adjusted relatively easily by trimming the resistor, but the resistance value of the type shown in FIG. 12 has a narrow width resistance. Is
It is actually difficult to adjust the resistance value by tomming.

Further, if there is a variation in the resistance value, the user who uses such a chip resistor as a current sensor portion cannot lead to accurate current detection. When a chip resistor as a current sensor is soldered on a circuit board, the internal resistance of this solder also tends to increase the total resistance as a sensor,
It is possible that the rated resistance value provided by the manufacturer of the chip resistor and the resistance value during actual use do not match, resulting in inaccurate current detection.

As described above, the configuration of the conventional chip resistor is not suitable when a low resistance value is required and it is used as a current sensor.

The present invention has been devised under the above circumstances, and a new chip resistor configured to be used as a sensor portion for measuring a low current value, and a new chip resistor. It is an object of the present invention to provide a current detection circuit and a current detection method to be used.

[0015]

In order to solve the above problems, the present invention takes the following technical means. That is, the chip resistor according to claim 1 of the present application is characterized in that a resistor and a pair of terminals extending in a branched shape from both ends of the resistor are formed on the chip substrate.

In the case where the resistor is formed by using a resistor material other than the conductor for forming the electrode terminal, and is formed in a batch pattern by using the same material as the material for forming the conductor terminal. It goes without saying that both are included.

According to a second aspect of the chip resistor of the present invention, among the total four terminals of the chip resistor of the first aspect, two terminals facing each other in a diagonal direction of the chip substrate are respectively connected to a current terminal and a voltage terminal. It is characterized by being a terminal.

The chip resistor also includes a resistor in which the resistor is formed in a thin shape with a material having a low sheet resistance value similar to that of forming the electrode terminal.

The resistance value of the resistor is, for example, 0.0.
It can be set to 1Ω to 1.00Ω.

To form a resistor having a low resistance value as described above, a thick film printing method can be used using a silver / palladium paste or a silver paste.

[0021] Claims 4 and 5 relate to a current detection circuit and a current detection method for detecting a current using the chip resistor of the present invention, and use the chip resistor of claim 2 or 3. It is characterized in that the current to be measured is detected by flowing the current to be measured between the current terminals and detecting the voltage drop between the voltage terminals.

[0022]

The basic idea of the present invention is that the current terminal and the voltage terminal are separately formed at both ends of the resistor formed on the chip substrate in the chip resistor.

Looking at the resistance value inspection at the manufacturing stage of the chip resistor, the voltage drop between both ends of the resistor not including the current terminal is caused via the voltage terminal while a constant current is applied between the current terminals. Can be accurately detected, and the resistance value between both ends of the resistor can be accurately measured by Ohm's formula.

When the chip resistor is used as the sensor part of the current detection circuit, the voltage drop between the voltage terminals is measured while flowing the current to be measured between the current terminals. In this case, since the resistance value of the resistor is accurately defined as described above, the current to be measured can be accurately detected by the Ohm's equation.

As described above, according to the present invention, the resistance value of the resistor itself is completely excluded from the internal resistance of the terminals formed by sandwiching the resistor on the chip substrate or the internal resistance of the solder when mounting on the substrate. Therefore, since the rated resistance value of the current detecting sensor can be set, the resistance value of the resistor can be easily accommodated within this error range even if the required error range is small.

As described above, the chip resistor of the present invention is
It is extremely suitable for use as a sensor part for low current detection, and the yield can be expected to improve.
In particular, when the current to be measured is small, it is suitable as a sensor for accurately detecting this.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments of the present invention will be described below.
A specific description will be given with reference to the drawings.

FIG. 1 and FIG. 2 show the plane and appearance of an embodiment of the chip resistor 1 of the present invention. The resistor 3 is provided on the upper surface of the chip substrate 2 made of alumina ceramic or the like.
Then, electrode terminals 4a, 4b, 4a, 4b extending in a branched shape from both ends of the resistor 3 are formed. In the present embodiment, the resistor 3 and each electrode terminal 4a, 4
b, 4a and 4b are integrally formed by thick film printing with a conductor paste such as silver / palladium paste or silver paste. Even if the resistor 3 is formed of the conductor paste as described above, as shown in FIG.
By reducing the width of the resistor portion and keeping the length constant, for example, 0.01Ω to 1.00Ω
That is, it can sufficiently function as a resistor having a low resistance value.

As will be described later, the chip resistor 1 of the present invention is planned to be used as a sensor portion for detecting a current, and current terminals 4a, 4a for passing a current through this resistor and a resistor. It is characterized in that the voltage terminals 4b, 4b for detecting the voltage drop between both ends of the body 3 are formed on a single chip substrate.

One (4a) of the two electrode terminals 4a and 4b branched from each end of the resistor 3 is a current terminal, and the other (4b) is a voltage terminal. It does not matter which of the two electrode terminals 4a and 4b branched from one end of the resistor 3 is a current terminal and which is a voltage terminal. However, in order to eliminate the directionality of the chip resistor 1, As shown in FIG. 1, two terminals 4a, 4a and 4b, which are diagonally opposed to each other with respect to the chip substrate 2,
It is preferable to use 4b as a current terminal and a voltage terminal.
In this way, the chip resistor 1 is replaced by 18 in FIG.
Even if it is inverted by 0 °, the same form is obtained, which is convenient for mounting.

The chip resistor 1 can be manufactured in the same manner as a general chip resistor. Although FIG. 1 shows a completed single chip resistor 1, this chip resistor is manufactured by forming a rectangular unit region on a material substrate in which plural rows and plural columns are formed by slits in a grid pattern. A total of 4 branches from the resistor 3 or both ends thereof.
A conductor wiring pattern consisting of one electrode terminal 4a, 4b, 4a, 4b is formed by thick film printing for all regions at once, and this material substrate is divided into substrates along the slits to finally obtain a pattern. A unit chip resistor such as 1 is obtained. After forming the thick film printing of the conductor pattern, if necessary, trimming 5 as shown in FIG. 1 is performed to adjust the resistance value of the resistor 3. The surface of the chip substrate other than the exposed portions of the electrode terminals 4a, 4b, 4a, 4b is covered with the protective glass coat 6.

The resistance value of the resistor 3 (or resistor portion) 3 of the chip resistor 1 as described above is measured as follows.

That is, the voltage drop between both voltage terminals 4b and 4b is measured while a constant current is passed between both current terminals 4a and 4a. Such measurement is performed by the so-called four-terminal method, and for the chip resistor 1 of the present invention, the measurement of the resistance value becomes like an equivalent circuit shown in FIG.

As is apparent from FIG. 3, considering that almost no current flows between the voltage terminals, the voltage terminals 4b and 4b are separated from the current terminals 4a and 4a by the resistor 3 (R ₁ ). Since the internal resistances (R ₂ , R ₃ ) are present in the current terminals 4a, 4a because they are directly connected to the ends of the resistor 3 (R
₁ ) The net resistance value can be measured accurately. In this respect, as shown in the measurement equivalent circuit of FIG. 13, the internal resistance (R ₂ , R ₃ ) of the terminal portion is conventionally measured because the voltage drop between the terminals c and c through which the measurement current flows is measured.
Since the resistance value (R ₁ + R ₂ + R ₃ ) including is measured, the resistance between the terminals as a whole changes greatly due to the fluctuation of the internal resistance of the terminals, which is a significant improvement. ing.

Thus, the resistance value of the portion to be made to function as a resistance is accurately measured, and as a result, the uniformity of the characteristics of the chip resistor according to the present invention is enhanced, and
It also leads to improved yield.

To use the chip resistor 1 described above as a current detection sensor in a low current detection circuit, for example, the following is performed.

FIG. 4 shows an example of an equivalent circuit when the current detecting circuit 7 is constructed by using the chip resistor 1 of the present invention.
In FIG. 4, reference numerals 4a and 4a denote current terminals on the chip, and reference numerals 4b and 4b denote voltage terminals on the chip, respectively. The resistance value of the resistor 3 is shown as R ₁ , and the internal resistance values of the electrodes 4a, 4b, 4a, 4b are shown as R ₂ to R ₅ , respectively. Further, in the figure, R ₆ to R ₉ represent the line resistance of the circuit board, and R ₁₀ ,
R ₁₁ represents the internal resistance in the voltage detector 8.

As is apparent from FIG. 4, the current terminals 4a,
A current to be measured is applied to 4a. For example, DC
When configuring the current detection circuit in the / DC converter, the power supply current is connected between the current terminals. Then, the input / output terminals of the voltage detector 8 are connected to the voltage terminals 4b and 4b.

As is clear from the above, when the detection circuit 8 is constructed, the resistance value R ₁ of the resistor 3 in the chip resistor is known, and the resistance value R ₁ is accurate. Stipulated in. Therefore, by measuring the voltage drop across the resistor 3 (resistance value R ₁ ), the value of the current flowing through the resistor 3 can be accurately measured according to Ohm's equation.

Since almost no current flows in the measuring circuit portion of the voltage detector, the internal resistances R ₄ and R ₅ of the voltage terminals 4b and 4b measure the voltage drop between both ends of the resistor 3. The above does not cause any inconvenience.

As described above, according to the present invention, the voltage terminals 4b and 4b are directly connected to both ends of the resistor 3 separately from the current terminals 4a and 4a through which the current to be measured flows, respectively. Internal resistances R ₂ and R _{3 of} terminals 4a and 4a
The current value of the current to be measured can be accurately detected without being affected by the above.

The chip resistor 1 of the present invention also has the advantage of being a chip resistor. That is, it can be easily surface-mounted on a circuit board, and
High integration of the circuit configuration can be achieved.

FIG. 5 shows a second embodiment of the chip resistor 1 of the present invention. In this embodiment, the configuration of the unit chip resistor 1 shown in FIG. 1 is a dual type in the lateral direction. The structure of each unit portion is the same as that shown in FIG.

In this embodiment, the following usage can be developed.

For example, assuming that the resistance value of each resistor 3 is 0.1Ω, when it is used as a resistance of 0.1Ω, as shown schematically in FIG. It is sufficient to use one of them, and as shown schematically in FIG. 7, by connecting each unit configuration in parallel, it is possible to use it as a resistance of 0.5Ω.

Of course, the scope of the present invention is not limited to the above embodiments. In the embodiment, the resistor 3
Was collectively formed by using the same conductor paste as that of the electrode terminals 4a, 4b, 4a, 4b, but as shown in FIG. 8, the resistor 3 was formed by using a predetermined resistor paste. The electrode terminals 4a, 4b, 4a, 4b can be formed separately. Even in this case, since the current terminal and the voltage terminal are separately conducted to the end portion of the resistor 3, the above-described effects of the present invention can be similarly expected.

[Brief description of drawings]

FIG. 1 is a plan view of an embodiment of a chip resistor of the present invention.

2 is an overall perspective view of the chip resistor shown in FIG. 1. FIG.

FIG. 3 is an equivalent circuit diagram in resistance value measurement of the chip resistor shown in FIG.

FIG. 4 is an example of a circuit diagram when the chip resistor shown in FIG. 1 is used as a current sensor in current measurement.

FIG. 5 is a plan view of another embodiment of the chip resistor of the present invention.

FIG. 6 is a schematic view showing an example of use of the chip resistor shown in FIG.

FIG. 7 is a schematic view showing an example of use of the chip resistor shown in FIG.

FIG. 8 is a plan view of still another embodiment of the chip resistor of the present invention.

FIG. 9 is a plan view showing a general configuration of a conventional chip resistor.

10 is a cross-sectional view taken along line XX of FIG.

FIG. 11 is a plan view showing a conventional configuration example of a low resistance chip resistor.

FIG. 12 is a plan view showing another example of the conventional configuration of the low resistance chip resistor.

FIG. 13 is an equivalent circuit diagram in resistance chip measurement of a conventional chip resistor.

[Explanation of symbols]

 1 chip resistor 2 chip substrate 3 resistor 4a current terminal 4b current terminal 7 current measurement circuit

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[Procedure amendment]

[Submission date] April 6, 1993

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Claims (5)

[Claims] 1. A chip resistor comprising a resistor and a pair of terminals extending in a branched shape from both ends of the resistor on a chip substrate. 2. The chip resistor according to claim 1, wherein, out of the total of four terminals, two terminals facing each other in a diagonal direction of the chip substrate are a current terminal and a voltage terminal, respectively. 3. A multiple chip resistor formed by connecting a plurality of the chip resistors according to claim 1 or 2. 4. The chip resistor according to claim 2 or 3, wherein the current to be measured is caused to flow between the current terminals, and the current to be measured is detected by detecting a voltage drop between the voltage terminals. A current detection circuit characterized in that 5. The chip resistor according to claim 2 or 3, wherein the measured current is caused to flow between the current terminals and the voltage drop between the voltage terminals is detected to detect the measured current. A method for detecting current, characterized by: