KR102441314B1 - Resistor and circuit board for current detection - Google Patents

Abstract

(Problem) To achieve stabilization of resistance value at a high level in a high-temperature region.
(Solution) The resistor for current detection is formed of a resistor material, the resistor material contains a Ni-Cr-Mo alloy, and the total mass ratio of the alloy is 63 mass% or more and 70 mass% or less of nickel, and 8 mass% of Cr. 22 mass % or more and 8 mass % or more and 25 mass % or less of said Mo are contained.

Description

Resistor and circuit board for current detection

The present invention relates to a resistor and a circuit board for detecting a current.

A resistor for current detection mounted on a circuit board through soldering, the resistor having a predetermined resistance value and having a main body formed by a metal plate, and a soldering unit connected to both ends of the main body and soldering the main body to the circuit board A resistor is disclosed (refer patent document 1).

Japanese Patent Application Laid-Open No. 2009-206290

In the resistor described in Patent Document 1, as a metal material for the body portion, a resistor material such as a copper nickel series, a nickel chromium series, or a copper manganese nickel series is used. However, in a general-purpose copper-manganese-nickel-based resistor material as a resistor material, manganese (Mn) in the component is easily oxidized at a high temperature, and the change in resistance value increases with the progress of oxidation.

For this reason, in a copper-manganese-nickel-type resistor material, the temperature of about 170-180 degreeC is set as the upper limit temperature which makes the fluctuation|variation of a resistance value fall within a permissible range.

On the other hand, in recent years, along with the spread of electric vehicles and high-functionality of electronic devices, the demand for high power and high heat resistance for circuit boards on which electronic components are mounted is increasing. In particular, development of semiconductor devices operating at high temperatures, such as SiC or GaN, which are called wide-gap power semiconductors, is in progress.

Accordingly, also for a resistor for current detection mounted on a circuit board, a specification that can be used even in a temperature range exceeding the above temperature, for example, 200°C or higher is required.

An object of the present invention is to provide a resistor for current detection that suppresses a large change in resistance value in a high temperature region, and a circuit board on which the resistor for current detection is mounted.

MEANS TO SOLVE THE PROBLEM As a result of repeating earnest research, the present inventors discovered that the alloy of nickel, chromium, and molybdenum had high heat resistance, paid attention to this, and came to complete this invention.

A resistor for current detection as an aspect of the present invention is formed of a resistor material, the resistor material contains an alloy of nickel, chromium, and molybdenum, and the total mass ratio of the alloy contains 63% by mass or more and 70% by mass of the nickel. Hereinafter, 8 mass % or more and 22 mass % or less of the said chromium and 8 mass % or more and 25 mass % or less of the said molybdenum are contained.

According to this aspect, by using the alloy of nickel, chromium, and molybdenum which has high heat resistance as a resistor material, it is a high temperature range WHEREIN: It can suppress that the change of a resistance value becomes large.

BRIEF DESCRIPTION OF THE DRAWINGS It is a top view explaining an example of the resistor for current detection which concerns on embodiment of this invention.
FIG. 2 is a side view of the resistor for current detection shown in FIG. 1 .
3 is a view for explaining a method of manufacturing the resistor for current detection according to the present embodiment.
4 is a view for explaining a circuit board on which a current detection resistor is mounted.

[Explanation of the resistor for current detection]

A resistor for current detection according to an embodiment of the present invention will be described in detail with reference to Figs.

<Structure of resistor for current detection>

BRIEF DESCRIPTION OF THE DRAWINGS It is a top view explaining an example of the resistor for current detection which concerns on this embodiment. Moreover, FIG. 2 is a side view of the resistor for current detection shown in FIG.

The resistor 1 for current detection is a plate-shaped shunt resistor formed of a resistor material containing an alloy of nickel (Ni), chromium (Cr), and molybdenum (Mo).

The resistor 1 for current detection has a body part 11 , a first connection part 12 , a second connection part 13 , a first standing part 14 , and a second standing part 15 .

The main body 11 has a rectangular shape, and is disposed to be spaced apart from the mounting surface of the circuit board by a predetermined distance.

One end of the first connecting portion 12 is connected to a mounting surface. In addition, the other end of the first connecting portion 12 is connected to the main body portion 11 via the first standing portion 14 . One end of the second connecting portion 13 is connected to a mounting surface. In addition, the other end of the second connecting portion 13 is connected to the main body 11 via the second standing portion 15 . The first standing portion 14 and the second standing portion 15 are provided with an end of the main body 11 and the first connecting portion 12 and the second connecting portion 13 so as to space the main body 11 away from the mounting surface. connect

In this embodiment, as shown in FIG. 2, the 1st connection part 12 and the 2nd connection part 13 respectively have the plating layer 16 for mounting surface formed on the surface opposite to a mounting surface, and the mounting surface facing It has a plating layer 17 for bonding formed on the opposite surface of the surface. Moreover, the 1st connection part 12 and the 2nd connection part 13 have the single-sided electrode 18 connected with the plating layer 16 for mounting surface and the plating layer 17 for bonding, respectively. In addition, the 1st connection part 12 and the 2nd connection part 13 do not need to be provided with the single-sided electrode 18. As shown in FIG.

The resistor 1 for current detection can be formed by pressing a plate body formed of a resistor material.

<Resistor material>

In the present embodiment, the resistor material forming the resistor 1 for current detection contains an alloy of nickel, chromium, and molybdenum, and in the total mass ratio of the alloy, 63 mass% or more and 70 mass% or less of nickel and chromium 8 mass % or more and 22 mass % or less, and 8 mass % or more and 25 mass % or less of molybdenum are contained.

From a viewpoint of improving the heat resistance of a resistor, the one with much content of molybdenum is good. However, since the hardness of molybdenum is high and molybdenum is brittle, when the content of molybdenum becomes excessive, the workability of the resistor material is deteriorated. For this reason, content of molybdenum is set to 8 mass % or more and 25 mass % or less.

Further, the resistor material may contain at least one of tungsten (W) and manganese (Mn) in a total mass ratio of 6% by mass or less of the alloy. When the resistor material contains at least one of tungsten and manganese in a total mass ratio of 6% by mass or less, heat resistance can be ensured without increasing the molybdenum content in the resistor material.

In the case of using a commercially available product as the resistor material, DSALOY625 (manufactured by Daidotokushu Co., Ltd.), DSALOY22 (manufactured by Daidotokushuco), and DSALOY242 (manufactured by Daidotokushuco) can be suitably used. DSALOY625 (made by Daido Tokushu Co., Ltd.) contains 22 mass % of chromium, 8 mass % of molybdenum, and 70 mass % of nickel. DSALOY22 (made by Daido Tokushuko Co., Ltd.) contains 21 mass % of chromium, 13 mass % of molybdenum, 3 mass % of tungsten, and 63 mass % of nickel. DSALOY242 (made by Daido Tokushu Co., Ltd.) contains 8 mass % of chromium, 25 mass % of molybdenum, and 67 mass % of nickel.

Among these, DSALOY242 containing 8 mass % of chromium, 25 mass % of molybdenum, and 67 mass % of nickel in particular has a small change in resistance value, and a low temperature coefficient of resistance (TCR) is used suitably.

[Manufacturing method of resistor for current detection]

3 is a view for explaining a method of manufacturing the resistor for current detection according to the present embodiment. The manufacturing method of the resistor for current detection is a method of performing press working so that the resistor material containing nickel, the alloy containing chromium, and molybdenum in the following ratio may become a predetermined shape. The said alloy contains 63 mass % or more and 70 mass % or less of nickel, 8 mass % or more and 22 mass % or less of chromium, and 8 mass % or more and 25 mass % or less of molybdenum in total mass ratio.

When the above-mentioned resistor material is heated to 200 degreeC or more, the change of resistance value becomes large over a predetermined period in which the temperature is rising. And it shows the behavior that the resistance value of a resistor material converges to a specific value after a predetermined period has passed. In this resistor material, the Vickers hardness of the resistor material in the state in which the change of the resistance value converges to a specific value is 200 HV or more and 240 HV or less.

Then, in this manufacturing method, the process which makes Vickers hardness 200HV or more and 240HV or less is performed to the resistor obtained by press working. Thereby, a resistor material with small fluctuation|variation in a resistance value can be manufactured.

Specifically, as shown in Fig. 3, before press working the above-mentioned alloy of nickel, chromium, and molybdenum into a predetermined shape, the Vickers hardness of the resistor material containing the alloy of nickel, chromium, and molybdenum is 220 HV or more and 290 HV or less. The first processing is performed so that Following the first process, the resistor material is press-worked, and the second process is performed so that the Vickers hardness of the resistor obtained by the press-working decreases by 15% to 25%.

A heat treatment can be used as the second treatment. In the second process, the resistor after press working is exposed to a temperature atmosphere of 175°C or higher for 200 hours or more. As an example of the second treatment, it is preferable to perform a treatment of exposure to a temperature atmosphere of 200° C. or higher for 250 hours. Thereby, the resistor whose Vickers hardness is 200 HV or more and 240 HV or less can be obtained.

Thus, the effect which suppresses the change of a resistance value from becoming large by giving a process previously to a resistor material so that Vickers hardness may be 200 HV or more and 240 HV or less can be heightened.

[circuit board]

4 is a view for explaining a circuit board on which a current detection resistor according to an embodiment of the present invention is mounted.

The circuit board 100 according to the present embodiment includes an insulating substrate 110 and a circuit pattern 120 formed on the insulating substrate 110 . The above-described resistor 1 for current detection is connected to the circuit pattern 120 by wire bonding 130 or solder-mounted electrode 140 in the first connecting portion 12 and the second connecting portion 13 . It is a circuit board formed by

In the present embodiment, as the insulating substrate 110 , a glass epoxy substrate, a metal substrate, or a ceramic substrate can be used. Among them, it is preferable that a ceramic substrate be used from the viewpoint of high heat resistance. In the present embodiment, at least one material selected from the group consisting of aluminum oxide, silicon nitride and aluminum nitride can be used as the ceramic substrate.

When a ceramic substrate is used, the ceramic substrate whose thickness is 0.1 mm or more and 1.0 mm or less can be used. From the viewpoint of the strength of the substrate, the thickness of the ceramic substrate is preferably 0.1 mm or more. On the other hand, from a viewpoint of heat dissipation, it is preferable that it is 1.0 mm or less.

As an electrode for connecting the circuit pattern 120 and the resistor 1 for current detection, copper (Cu) is generally used. However, the copper electrode has low heat resistance and is easily oxidized. For this reason, in this embodiment, in order to improve heat resistance, nickel-type plating and gold-type plating can be used. Among these, nickel-tungsten plating, nickel-phosphorus plating, nickel-tungsten/gold plating, nickel-phosphorus/gold plating, nickel/gold plating, or the like is preferably used.

[Other embodiments]

As mentioned above, although embodiment of this invention was described, the said embodiment is only showing a part of application example of this invention, It is not the meaning which limits the technical scope of this invention to the specific structure of the said embodiment. For example, the shape of the resistor 1 for current detection according to the present embodiment is not limited to that described in FIG. 1 .

(Example)

A resistor for current detection according to an embodiment of the present invention was produced, and heat resistance and resistance characteristics were evaluated. The production method and evaluation method of the specimen are as follows.

[Production of specimens]

<Example 1>

In Example 1, as a nickel-chromium-molybdenum alloy (hereinafter referred to as a Ni-Cr-Mo alloy) as a resistor material, DSALOY625 (Daido) containing 22 mass% of chromium, 8 mass% of molybdenum, and 70 mass% of nickel Tokushu Co., Ltd. make, 22Cr-8Mo-70Ni) was used. After processing 22Cr-8Mo-70Ni into plate shape, the resistor shown in FIG. 1 and FIG. 2 was produced. The dimensions of each part of the obtained resistor are as follows.

Ld=5.0mm

Lc=3.2mm

d=0.2mm

<Example 2>

In Example 2, as a Ni-Cr-Mo alloy of the resistor material, DSALOY22 (manufactured by Daido Tokushko Co., Ltd.) containing 21 mass % of chromium, 15 mass % of molybdenum, 3 mass % of tungsten, and 63 mass % of nickel , described as 21Cr-13Mo-3W-63Ni) was used. Other than that, it carried out similarly to Example 1, and produced the specimen.

<Example 3>

In Example 3, as a Ni-Cr-Mo alloy of the resistor material, DSALOY242 (manufactured by Daido Tokushuko Co., Ltd., 8Cr-25Mo-67Ni) containing 8% by mass of chromium, 25% by mass of molybdenum, and 67% by mass of nickel stated) was used. Other than that, it carried out similarly to Example 1, and produced the specimen.

<Comparative example>

In the comparative example, instead of the Ni-Cr-Mo alloy, manganese was used as the copper-manganese-nickel-based resistor material. Other than that, it carried out similarly to Example 1, and produced the specimen.

[How to measure]

<Volume resistivity>

Since the width and thickness of the body part 11 of the specimen are constant, the cross-sectional area of the body part 11 is uniformly cross-sectional area S(cm ² ) along the longitudinal direction of the body part 11 . For this reason, the volume resistivity ρ of the resistor material is determined by the voltage V between the first connecting portion 12 and the second connecting portion 13, the current I, the cross-sectional area S(cm ² ), and the first connecting portion 12 and the second connecting portion 13 . From the length Ld (cm) between the connection parts 13, it computed with the following formula|equation.

ρ = (V/I) × (S/Ld) [10 ^{- 6} Ω cm]

In addition, in this measurement, the allowable range of the volume resistivity ρ was set to 120 to 150 [10 ^{- 6} Ω·cm].

<Measurement of temperature coefficient of resistance (TCR)>

Temperature coefficient of resistance (TCR) shows the ratio of the change of the internal resistance value by the temperature change of a resistor, Computing with the following formula|equation.

Resistance temperature coefficient (ppm/°C) = (R-Ra)/Ra÷(T-Ta)×1000000

In this formula, Ra: resistance value in reference temperature, Ta: reference temperature, R: resistance value in a steady state, T: temperature at which it becomes a steady state.

In this example, Ta=25°C and T=100°C were set. In addition, the allowable range of TCR was set to ±100ppm/℃ based on the product specification. A measurement result is shown in 1st table|surface.

<Heat resistance test: rate of change of resistance value of resistor>

The heat release test was done to the specimen of Examples 1-3 and a comparative example. In the heat release test, the specimen was heated at 200°C and held at 200°C for a predetermined time. The change in the resistance value according to the difference in the standing time was measured.

The change rate of the resistance value was computed with the following formula.

Resistance value change rate (%)={(Rh-Ra)/Ra}×100

In this formula, Ra is a resistance value in the reference temperature before a heat standing test, and Rh is a resistance value after predetermined time elapses in a heat standing test. The results are shown in Table 1.

In this measurement, even if it reached 1000 hours, the change rate of the resistance value made the test piece which entered the range of +/-0.50% pass.

<Vickers hardness>

Vickers hardness can be measured according to Japanese Industrial Standards JIS Z2244: 2009 (Vickers hardness test-test method). A hardness meter (for example, MicroVickers hardness meter HMV-G21: Shimadzu Corporation) was used for the measurement of Vickers hardness. Vickers hardness was measured under the conditions of, for example, a test temperature of 25°C, a test force of 100 gf, an approach speed of 20 µm/s of a diamond indenter, and a holding time of 10 seconds of the test force. It is preferable to smooth the surface of the test piece with a polishing machine (eg, automatic polishing machine Rana-3: IMT) or the like to remove contamination.

[result]

Table 1 shows the results of the heat resistance test, the volume resistivity, the temperature coefficient of resistance (TCR), and the Vickers hardness.

In Examples 1-3 which performed a heat-resistance test, the change rate of the resistance value of a specimen was between about 0 to 0.20% or 0 to 0.40%. Accordingly, it was found that when the Ni-Cr-Mo alloy according to the present embodiment was used as the resistor material, the rate of change in the resistance value of the resistor material could be stabilized even at a high temperature of 200°C. The rate of change of these resistance values is sufficiently low and is considered to be a good value. Also in any Example, it turned out that the rate of change of resistance value was observed remarkably from the start of heating to 250 hours. Also, after about 250 hours, the rate of change of the resistance value did not change.

In view of the above, the change in the resistance value of the resistor material can be stabilized by performing the heat treatment in advance under the conditions of a heating temperature of 200°C and a heating time of 250 hours. Accordingly, the current detection resistor can be mounted on the circuit board in a state where the change rate is small.

In this respect, the resistor for current detection according to the present embodiment contains an alloy of nickel, chromium, and molybdenum, and contains 63 mass% or more and 70 mass% or less of nickel and 8 mass% or more and 22 mass% of chromium in the total mass ratio of the alloy. Hereinafter, by forming the resistor material containing 8% by mass or more and 25% by mass or less of molybdenum, it is possible to achieve stabilization of the resistance value at a high level in a higher temperature region.

One… Resistor for current detection 11… body part
12… 1st connection part 13... second connection
14… 1st standing part 15... 2nd standing part
16… Plating layer for mounting surface 17... Plating layer for bonding
100… circuit board 110... insulated substrate
120… circuit pattern 130... wire bonding

Claims (9)

A resistor for current detection, comprising:
It is formed as a plate body of a resistor material,
The resistor material includes an alloy of nickel, chromium, and molybdenum,
63% by mass or more and 70% by mass or less of the nickel in the total mass ratio of the alloy;
8% by mass or more and 22% by mass or less of the chromium;
It contains 8 mass % or more and 25 mass % or less of the said molybdenum,
A resistor for current detection, characterized in that the rate of change of the resistance value after the lapse of 1000 hours at 200°C is within ±0.50%. According to claim 1,
The resistor for current detection, wherein the resistor material contains at least one of tungsten and manganese in a total mass ratio of 3% by mass or more and 6% by mass or less. 3. The method of claim 2,
The resistor for current detection, characterized in that the Vickers hardness of the resistor material is 200 HV or more and 240 HV or less. 3. The method of claim 2,
a body portion having a rectangular shape, facing the mounting surface, and disposed to be spaced apart from the mounting surface by a predetermined distance;
a first connection part connected to the mounting surface;
a second connection part connected to the mounting surface;
a first standing part connecting the body part and the first connection part to separate the body part from the mounting surface;
A second standing part connecting the body part and the second connection part to separate the body part from the mounting surface.
A resistor for current detection, characterized in that it has a. 5. The method of claim 4,
The resistor for current detection, characterized in that the first connecting portion and the second connecting portion have a plating layer. A circuit board in which a predetermined circuit pattern is formed on an insulating substrate,
A circuit board in which the current detection resistor according to claim 4 or 5 is connected to the circuit pattern by wire bonding in the first connecting portion and the second connecting portion. A method for manufacturing a current sensing resistor, comprising:
An alloy of nickel, chromium, and molybdenum is included, wherein the nickel content is 63 mass % or more and 70 mass % or less, the chromium is 8 mass % or more and 22 mass % or less, and the molybdenum is 8 mass % or more and 25 mass % by the total mass ratio of the alloy. % or less, and press-working into a predetermined shape a plate body of a resistor material in which the rate of change of the resistance value after lapse of 1000 hours at 200°C is ±0.50%. 8. The method of claim 7,
A method for manufacturing a resistor for current detection, wherein, after the press working, a process is performed so that the Vickers hardness of the resistor material is 200 HV or more and 240 HV or less. 9. The method of claim 8,
A method for manufacturing a resistor for current detection, wherein, before the press working, a process is performed so that the Vickers hardness of the resistor material is 220 HV or more and 290 HV or less.

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