DE102021115112A1 - RESISTOR AND CIRCUIT FOR DETECTING CURRENT - Google Patents

Abstract

A current detection resistor according to one aspect is formed of a resistance material and has an alloy of nickel, chromium and molybdenum, the alloy having a nickel content of 63% by mass or more and 70% by mass or less, a chromium content of 8% by mass or more and 22% by mass or less and a molybdenum content of 8% by mass or more and 25% by mass or less in the total mass ratio of the alloy.

Description

TECHNOLOGICAL AREA

The present invention relates to a current detection resistor and a circuit substrate.

TECHNOLOGICAL BACKGROUND

As a current detection resistor implemented on a circuit substrate via a solder, a resistor will be described which comprises a main body formed from a metal plate having a predetermined resistance value and a soldered portion provided on both side ends of the main body containing the Main body soldered to the circuit substrate (see JP 2009-206290A ).

SUMMARY OF THE INVENTION

[The problem to be solved by the invention]

In the in JP 2009-206290A a resistor material such as a manganese-nickel-based alloy, a nickel-chromium-based alloy and a copper-manganese-nickel-based alloy is used as the metallic material for the main body. With a general copper-manganese-nickel-based resistor material as the resistor material, however, manganese (Mn) in the components is easily oxidized at high temperatures, and the change in resistance becomes large as the oxidation proceeds.

For this reason, in the case of the copper-manganese-nickel-based resistance material, the upper limit temperature is set to the temperature of about 170 ° C. to 180 ° C. at which the change in the resistance value can be kept within an allowable range.

On the other hand, in recent years, with the spread of electric vehicles and the increasing functionality of electronic devices, there has been a growing demand for circuit substrates for assembling electronic components with higher performance and higher heat resistance. In particular, the development of a semiconductor device such as wide-gap power semiconductors called SiC and GaN that operates at a high temperature has been promoted.

Therefore, the current detection resistors mounted on the circuit substrate have been thought to have specifications that allow their use at temperatures higher than those mentioned above, e.g. B. at 200 ° C or higher.

It is an object of the present invention to provide a current detection resistor which suppresses a large change in resistance value in a high temperature area and a circuit board on which the current detection resistor is mounted.

[A means of solving the problem]

As a result of intensive research, the inventors of the present application have found that an alloy of nickel, chromium and molybdenum has high heat resistance. The inventors have focused on this fact and made the present invention.

A current detection resistor in accordance with one aspect is formed from a resistor material. The resistor material includes an alloy of nickel, chromium and molybdenum, the alloy having a nickel content of 63 mass percent or more and 70 mass percent or less, a chromium content of 8 mass percent or more and 22 mass percent or less, and a molybdenum content of 8 mass percent or more and 25 Contains percent by mass or less in the total mass ratio of the alloy.

[Effect of the inventions]

According to this aspect, by using the alloy of nickel and chromium and molybdenum having high heat resistance as a resistance material, it is possible in a high temperature region to suppress the change in resistance value from being increased.

Figure list

• [ 1 ] 1 Fig. 13 is a plan view showing an exemplary current detection resistor according to an embodiment of the present invention.
• [ 2 ] 2 is a side view of the in 1 current detection resistor shown.
• [ 3 ] 3 Fig. 13 is a diagram showing a method of manufacturing a current detection resistor according to the present embodiment.
• [ 4th ] 4th Fig. 13 is a diagram showing a circuit substrate in which a current detection resistor is mounted.

DESCRIPTION OF THE EMBODIMENTS

[Explanation of a current detection resistor]

With reference to 1 until 4th a current detection resistor according to an embodiment of the present invention will be described in detail.

<Structure of a current detection resistor>

1 Fig. 13 is a plan view showing an exemplary current detection resistor according to an embodiment of the present embodiment. 2 is a side view of the in 1 current detection resistor shown.

A current detection resistor 1 is a plate-shaped measuring resistor formed from a resistance material containing an alloy of nickel (Ni), chromium (Cr) and molybdenum (Mo).

The current detection resistor 1 includes a main body 11, a first connection part 12, a second connection part 13, a first rising part 14, and a second rising part 15.

The main body 11 has a rectangular shape and is spaced a predetermined distance from a mounting surface of a circuit substrate.

One end of the first connecting part 12 is connected to the mounting surface. The other end of the first connecting part 12 is also connected to the main body 11 via the first rising part 14. And one end of the second connection part 13 is connected to the mounting surface. The other end of the second connecting part 13 is also connected to the main body 11 via the second rising part 15. The first rising part 14 and the second rising part 15 connect the ends of the main body 11 to the first connecting part 12 and the second connecting part 13, respectively, to separate the main body 11 from the mounting surface.

In the present embodiment, as shown in 2 shown, the first connecting part 12 and the second connecting part 13 have an electroplated layer for the mounting surface 16, which is formed on a surface facing the mounting surface, a galvanic layer for the bond 17, which is formed on the opposite surface of the surface facing the mounting surface, and an end electrode 18 which is formed continuously with the electroplated layer for the mounting surface 16 or the electroplated layer for the adhesive bond 17. Incidentally, the first connecting part 12 and the second connecting part 13 do not have to be provided with the end-face electrodes 18.

The current detection resistor 1 can be formed by pressing a plate-shaped body made of the resistor material.

<the resistor material>

In the present embodiment, the current detection resistor 1 formed of the resistor material contains the alloy of nickel, chromium and molybdenum, the alloy having a nickel content of 63 mass percent or more and 70 mass percent or less, a chromium content of 8 mass percent or more and 22 mass percent or less and contains a molybdenum content of 8 mass percent or more and 25 mass percent or less of the total mass ratio of the alloy.

From the viewpoint of improving the heat resistance of the resistor material, a higher content of molybdenum may be used in some embodiments. However, the hardness of molybdenum is high and molybdenum is fragile. Therefore, if the content of molybdenum is too high, the processability of the resistor material decreases. For this reason, the content of molybdenum should be set to 8 mass% or more and 25 mass% or less in the total mass ratio of the alloy.

In addition, the resistor material can contain at least one of the elements tungsten (W) or manganese (Mn), the content of at least one of the elements tungsten (W) or manganese (Mn) in a total mass ratio of this alloy being 6 mass percent or less. By containing at least one of tungsten or manganese in a total ratio of this alloy of 6 mass% or less, heat resistance can be secured without increasing a content of molybdenum in the resistor material.

When commercially available products are used as the above resistor material, DSALOY625 (manufactured by Daido Steel Co., Ltd.), DSALOY22 (manufactured by Daido Steel Co., Ltd.), and DSALOY242 (manufactured by Daido Steel Co., Ltd.) are suitable. DSALOY625 contains 22 mass percent chromium, 8 mass percent molybdenum and 70 mass percent nickel. DSALOY22 contains 21 mass percent chromium, 13 mass percent molybdenum, 3 mass percent tungsten and 63 mass percent nickel. DSALOY242 contains 8 mass percent chromium, 25 mass percent molybdenum and 67 mass percent nickel.

Among them, DSALOY242 containing 8 mass% chromium, 25 mass% molybdenum and 67 mass% nickel is particularly suitable because the change in resistance value is small and the temperature coefficient of electrical resistance (TCR) is low.

[Manufacturing method for a current detection resistor]

3 Fig. 13 is a diagram showing a method of manufacturing the current detection resistor according to the present embodiment. The manufacturing method for the current detection resistor is to press-work a resistor material containing an alloy of nickel, chromium and molybdenum in the following proportions to form a predetermined shape. The alloy contains a nickel content of 63 mass% or more and 70 mass% or less, a chromium content of 8 mass% or more and 22 mass% or less, and a molybdenum content of 8 mass% or more and 25 mass% or less in a total mass ratio.

When the above-described resistor material is heated to 200 ° C. or more, the change in resistance value increases as the temperature is increased for a predetermined period of time. After the predetermined period of time has passed, the resistance value of the resistor material has a behavior that converges at a certain point. In this resistor material, in a state where the change in resistance value converges in a certain state, a Vickers hardness value is equal to or greater than 200 HV and is equal to or less than 240 HV.

Therefore, the resistor body obtained by performing press working in this manufacturing method is treated so that the Vickers hardness value becomes 200 HV or more and 240 HV or less. This makes it possible to manufacture the resistor material with small changes in the resistance value.

In particular, as in 3 shown, prior to performing the press working of the above-mentioned alloy of nickel, chromium and molybdenum into the predetermined shape, the first treatment is carried out so that the Vickers hardness value of the resistor material containing the above-mentioned alloy of nickel, chromium and molybdenum becomes 220 HV or more and 290 HV or less. After the ers In the tenth treatment, the resistor material is pressed, and the second treatment is carried out so that the Vickers hardness value of the resistor body obtained by the press working is decreased by 15% to 25%.

A heat treatment can be used as a second treatment. In the second treatment, the resistor material is exposed to an atmosphere of 175 ° C or higher for 200 hours or more after the press working. As an example of the second treatment, it is preferable to expose the resistor material to an atmosphere of 200 ° C. or more for 250 hours. This makes it possible to obtain the resistor material whose Vickers hardness value is equal to or more than 200 HV and equal to or less than 240 HV.

Thus, it is possible to increase the resistance value change suppressing effectiveness by performing the previous treatment of the resistor material so that the Vickers hardness value is equal to or more than 200 HV and equal to or less than 240 HV.

[Circuit substrate]

4th Fig. 13 is a diagram showing a circuit substrate in which the current detection resistor is mounted.

A circuit substrate 100 according to the present embodiment has an insulation substrate 110 and a circuit pattern 120 formed on the insulation substrate 110. The above-described current detection resistor 1 is a circuit substrate formed in the first connection part 12 and the second connection part 13 via a soldered electrode 140 or a bonding wire 130 is connected to the circuit pattern 120.

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

When using the ceramic substrate, it is possible to use a thickness of the ceramic substrate of 0.1 mm or more and 1.0 mm or less. From the viewpoint of the strength of the substrate, it is possible that the thickness of the ceramic substrate is preferably 0.1 mm or more. On the other hand, it is preferable that the thickness is 1.0 mm or less from the viewpoint of heat dissipation.

Generally, copper (Cu) is used as an electrode to connect the circuit pattern 120 to the current sense resistor 1. However, the copper electrode has poor heat resistance and is easy to oxidize. Therefore, in this embodiment, it is possible to use a nickel-based coating and a gold-based coating in order to improve the heat resistance.

[Other embodiments]

Although the embodiments of the present invention have been described above, the above embodiments illustrate only part of the application examples of the present invention, and the technical scope of the present invention should not be limited to the specific configurations of the above-described embodiments. For example, the shapes of the current detection resistor 1 according to the present embodiment are not limited to those in FIG 1 the forms described are limited.

EXAMPLE

The current detection resistor according to the embodiment of the present invention was manufactured, and the heat resistance and resistance properties were evaluated. A preparation method and an evaluation method of the test items are described below.

[Preparation of the test items]

<Practical example 1>

In a practical example 1, DSALOY625 (manufactured by Daido Steel Co., Ltd., designated 22Cr-8Mo-70Ni) containing 22 mass percent chromium, 8 mass percent molybdenum and 70 mass percent nickel was used as a nickel-chromium-molybdenum alloy ( hereinafter referred to as Ni-Cr-Mo alloy) is used for the resistor material. In the 1 and 2 resistors shown were prepared in a plate shape after processing 22Cr-8Mo-70Ni. The dimensions of each part of the resistor obtained are as follows.

$$\text{Ld}=5.0\text{mm}$$

$$\text{Lc}=3.2\text{mm}$$

$$\text{d}=0.2\text{mm}$$

<Practical example 2>

In a practical example 2, DSALOY22 (manufactured by Daido Steel Co., Ltd., designated as 21Cr-13Mo-3W-63Ni), which contains 21 mass percent chromium, 13 mass percent molybdenum, 3 mass percent tungsten and 63 mass percent nickel, was named Ni Cr-Mo alloy used for the resistor material. Except for this, the test piece of Practical Example 2 was manufactured in the same manner as in Practical Example 1.

<Practical example 3>

In Practical Example 3, DSALOY242 (manufactured by Daido Steel Co., Ltd., designated as 8Cr-25Mo-67Ni) containing 8 mass percent chromium, 25 mass percent molybdenum and 67 mass percent nickel was used as a Ni-Cr-Mo alloy for the resistor material used. Except for this, the test piece of Practical Example 3 was manufactured in the same manner as in Practical Example 1.

<Comparative example>

In a comparative example, instead of the Ni-Cr-Mo alloy, a manganin based on copper-manganese-nickel was used as the Ni-Cr-Mo alloy for the resistor material. Except for this, the test piece of Comparative Example was manufactured in the same manner as in Practical Example 1.

[Measuring method]

<Volume resistance>

Since the width and thickness of the main body 11 are constant in the specimen, a cross-sectional area of the main body 11 has a uniform cross-sectional area S (cm ² ) along the lengthwise direction of the main body 11. For this reason, the volume resistivity of the withstand voltage p was determined by the following equation using a Voltage V between the first connection part 12 and the second connection part 13, a current I, the cross-sectional area S (cm ² ), and a length Ld (cm) between the first connection part 12 and the second connection part 13 are calculated. $$\mathrm{\rho }=\left(\text{V}/\text{I.}\right)\times \left(\text{S.}/\text{Ld}\right)\left[{10}^{-\mathrm{6th}}\mathrm{\Omega }\cdot \text{cm}\right]$$

Note that an allowable range of volume resistance is set to 120 to 150 [10-6Ω · cm] for this measurement.

<Measurement of the temperature coefficient of electrical resistance (TCR)>

A temperature coefficient of electrical resistance (TCR) represents the ratio of change in an internal resistance value due to a change in temperature of a resistor body, it is calculated by the following equation. $$\begin{array}{l}\text{Temperature coefficient of resistance}\left(\text{ppm}/°\text{C.}\right)=\left(\text{R.}-\text{Ra}\right)/\text{Ra}÷\left(\text{T}-\text{Ta}\right)\\ \times 1000000\end{array}$$

In this equation, Ra is a resistance value at a reference temperature, Ta is a reference temperature, R is a resistance value in the steady state, T is the temperature at which the steady state occurs.

In this embodiment, Ta was set to 25 ° C and T to 100 ° C. Incidentally, the allowable range of the TCR has been set to ± 100 ppm / ° C based on the product specifications. The results of the measurement are shown in Table 1.

<Heat resistance test: rate of change of a resistance value of the resistor body>

The specimens of Practical Examples 1 to 3 and the Comparative Example were subjected to a thermal leak test. The test specimens were heated to 200 ° C. and held at 200 ° C. for a specified time. The change in the resistance value due to the different dwell times was measured.

The rate of change of the resistance value is calculated by the following equation.

The rate of change of resistance value (%) = {(Rh-Ra) / Ra} x 100 In this equation, Ra is a resistance value at a reference temperature before the thermal leak test, Rh is a resistance value after a predetermined time in the thermal leak test. The results are shown in Table 1.

In this measurement, the specimens whose rate of change in resistance value was within ± 0.50% even after 1000 hours were considered to have passed the test.

<Vickers hardness value>

A Vickers hardness value can be measured according to Japanese Industrial Standard JIS Z2244: 2009 (Vickers hardness value test method). A hardness meter (e.g. Micro Vickers hardness meter HMV-G21: Shimazu Corporation) was used to measure the Vickers hardness value. The Vickers hardness value is measured e.g. at a test temperature of 25 ° C, a test force of 100 gf, an approach speed of the diamond penetrator of 20 µm / s and a holding time of the test force of 10 seconds. The surface of the test body is preferably smoothed and impurities or the like removed with a polishing machine (e.g. automatic polishing machine Rana-3: IMT) or the like.

[Results]

The results of the heat resistance test, volume resistivity, temperature coefficient of resistance (TCR) and Vickers hardness value are shown in Table 1.

[Table 1]

TABLE 1 Practical example 1 Practical example 2 Practical example 3 Comparative example Description of the product DSALOY625 DSALOY22 DSALOY242 - Composition of the resistor material 22Cr-8Mo-Ni 21Cr-13Mo-3W-Ni 8Cr-25Mo-Ni Manganin Test of heat resistance: rate of change of a resistance value ΔR [%] 250 h 0.33 0.17 0.21 -0.78 500 h 0.37 0.18 0.23 -0.78 750 h 0.39 0.20 0.24 -0.78 1000 h 0.41 0.21 0.25 -0.78 Volume resistance (25 ° C) [10 ^-6 Ω · cm] 134 122 133 43 TCR (100 ° C / 25 ° C) [ppm / ° C] +67 +98 +42 +20 Before heat treatment Vickers hardness value [HV] 279 271 273 140 After a heat treatment of 175 ° C and 250 h Vickers hardness value [HV] 235 207 233 100

In Practical Examples 1 to 3 in which heat resistance tests were carried out, the rate of change in the resistance value of the samples is generally within 0 to 0.20% or 0 to 0.40%. Therefore, when the Ni-Cr-Mo alloy is used as a resistor material, it has been found that the rate of change in the resistance value of the resistor material can be stabilized even at a high temperature of 200 ° C. These rates of change in resistance values are sufficiently low and are considered good values. In all cases, the rate of change in resistance values from the start of heating up to 250 hours was found to be significant. In general, the rate of change in the resistance value leveled off after 250 hours.

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

Therefore, the current detection resistor according to the present embodiment achieves the stabilization of the resistance value at a higher level in a higher temperature range by forming the resistor material comprising the alloy of nickel, chromium and molybdenum in which the alloy has a nickel content of 63 mass percent or more and 70 mass percent or less, a chromium content of 8 mass% or more and 22 mass% or less and a molybdenum content of 8 mass% or more and 25 mass% or less in the total mass ratio of the alloy.

List of reference symbols

1

Current detection resistor

11th

Main body

12th

first connecting part

13th

second connecting part

14th

first rising part

15th

second ascending part

16

Electroplated layer for mounting surface

17th

Electroplated layer for gluing

100

Circuit substrate

110

Isolation substrate

120

Circuit pattern

130

Bond wire

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• JP 2009206290 A [0002, 0003]

Claims (9)

Current detection resistor formed from a resistive material, wherein the resistor material comprises an alloy of nickel, chromium and molybdenum in which the alloy a nickel content of 63 mass percent or more and 70 mass percent or less, a chromium content of 8 mass percent or more and 22 mass percent or less, and has a molybdenum content of 8 mass percent or more and 25 mass percent or less based on the total mass ratio of the alloy. Current detection resistance according to Claim 1 wherein the resistance material comprises at least one element of the group: tungsten or manganese, wherein a content of at least one of tungsten or manganese is 6 mass percent or less in a total mass ratio of the alloy. Current detection resistance according to Claim 1 or 2 , wherein a Vickers hardness value of the resistor material is equal to or greater than 200HV and is equal to or less than 240HV. Current detection resistance according to one of the Claims 1 until 3 further comprising: a rectangularly shaped main body, the main body being disposed against a mounting surface and spaced a predetermined distance from the mounting surface of a circuit substrate; a first connector connected to the mounting surface; a second connector connected to the mounting surface; a first rising part connecting the main body to the first connecting part for separating the main body from the mounting surface; and a second rising part connecting the main body to the second connecting part for separating the main body from the mounting surface. Current detection resistance according to Claim 4 , wherein the first connection part and the second connection part are provided with an electroplating layer. A circuit substrate forming a predetermined circuit pattern on an insulating substrate, comprising: the current detection resistor after Claim 4 or 5 wherein the current detection resistor is connected to the circuit pattern at the first connection part and the second connection part by bonding wire. A manufacturing method for a current detection resistor, the manufacturing method comprising: Performing press processing of a resistor material into a predetermined shape, wherein the resistor material contains an alloy of nickel, chromium and molybdenum in the following proportions to form a predetermined shape, and the alloy contains a nickel content of 63 mass% or more and 70 mass% or less, a chromium content of 8 mass% or more and 22 mass% or less, and a molybdenum content of 8 mass% or more and 25 mass% or less in a total mass ratio. Method for producing the current detection resistor according to Claim 7 , wherein after the press processing, treatment is performed such that a Vickers hardness value of the resistor material is equal to or greater than 200 HV and is equal to or less than 240 HV. Method for producing the current detection resistor according to Claim 7 or 8th , wherein a treatment is performed before the press working so that the Vickers hardness value of the resistor material is equal to or greater than 220 HV and is equal to or less than 290 HV.

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