JP4409385B2 - Resistor and manufacturing method thereof - Google Patents

Description

  The present invention relates to a resistor having a low resistance value on the order of mΩ (milliohm) suitable for current detection and the like, and more particularly to a structure and a manufacturing method of the above-mentioned resistor of high power type.

  As a conventional high power type current detection resistor, for example, a thin film resistor is formed on a ceramic substrate, and the ceramic substrate is bonded and fixed to a heat sink with an adhesive or the like (Patent Document 1). reference). In this resistor, a lead terminal for supplying a current to the resistor and detecting a voltage generated at both ends of the resistor is connected and fixed to an electrode portion provided on the resistor by solder.

In the case of a current detection resistor, the contact resistance generated at the joint between the lead terminal and the electrode provided on the resistor must be as small as possible, and the mechanical strength and mechanical / electrical strength of the joint are required. High reliability such as stability is required.
Japanese Patent Laid-Open No. 3-141607

  However, in the conventional current detection resistor, for example, in the one described in Patent Document 1, the lead terminal is joined to the electrode portion of the resistor by solder connection, and the contact resistance and mechanical / electrical stability of the joined portion are connected. There is a problem that it is not always sufficient for high demands such as sex.

  In addition, a current detection resistor having a low resistance value on the order of mΩ (milliohm) has a structure that is as small and compact as possible, has a high resistance value accuracy, a low temperature coefficient of resistance (TCR), and a reduction in manufacturing cost. It has been requested.

  The present invention has been made in view of the circumstances described above, and provides a current detecting resistor having a compact and compact structure and a manufacturing method thereof, which can obtain good electrical characteristics and high reliability. With the goal.

To solve the above problem, a resistor of the present invention includes a heat radiation substrate formed of a metal plate, a resistor made of a resistive metal plate which is fixed via an insulating material heat-dissipating substrate, under the resistive element antibodies and four base is convex portion provided in the side edges, joined to each of the base under the end, four consisting of highly conductive metal material projecting from the lower end portion of the heat radiating board and a lead terminal, said end portions of the lead terminals are joined by respective thermal diffusion bonded to the base end portion of the resistor, and the width of the base width as the resistor of said lead terminals has become the same The two outer terminals of the four lead terminals function as current terminals, and the inner two function as voltage detection terminals .

  Thereby, the lead terminal is made of a highly conductive metal material such as Cu, and heat is applied to the base end portion of the resistor made of a resistance metal material such as a Cu-Ni alloy, a Ni-Cr alloy, or a Cu-Mn alloy. Bonded by diffusion bonding. For this reason, mechanically high joint strength is obtained between the lead terminal and the resistor, electrical contact resistance is small, and high mechanical and electrical reliability is obtained. And since the resistance metal plate is directly fixed to a heat dissipation substrate such as an aluminum substrate through an insulating material, a good heat dissipation is obtained, and a current detecting resistor having a high power capacity with a compact and compact structure Is provided.

In addition, the method for manufacturing a resistor according to the present invention includes forming a strip-shaped composite material plate in which a resistance metal plate and a highly conductive metal plate are heat diffusion bonded at respective side edge portions, and the strip- shaped composite material plate part by punching as according to the resistance metal plate material, to form a single four base of convex lower edge of the resistor metal sheet by punching, and four at the end thereof the form the form of lead terminals made of a highly conductive metal, and bonded using an insulation adhesive composite sheet material in a band radiating substrate of the strip, the high conductivity of the four composite material plate of the strip The resistive metal plate portion on which the lead terminal made of a conductive metal is formed is separated into individual resistors, the resistance value of the resistor is adjusted, and the strip-shaped heat radiation substrate is divided into individual resistors. It is characterized by this.

  As a result, a composite material plate material is formed by thermally diffusing and bonding resistance metal plate material and highly conductive metal plate material at each side edge portion, and a part of the composite material plate is punched to heat diffuse the highly conductive metal lead terminals. A resistor made of a resistive metal plate fixed by bonding can be formed. For this reason, the lead terminal of a highly conductive metal can be fixed to a resistor made of a resistive metal plate with high mechanical strength and low electrical contact resistance by a simple process as described above. Then, after forming the lead terminal by the above punching process, by performing a heat treatment, mechanical strain due to the punching process such as a press can be removed, and a highly reliable resistor with a small change in resistance over time is obtained. Can be produced.

  In general, according to the present invention, there is provided a current detection resistor having high mechanical and electrical reliability, good heat dissipation, and a small and compact structure and high power capacity. . And the said resistor can be manufactured economically by a simple manufacturing process.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, in each figure, the same code | symbol is attached | subjected to the member or element which has the same effect | action or function, and the overlapping description is abbreviate | omitted.

  FIG. 1 shows a current detection resistor according to an embodiment of the present invention, and FIG. 2 shows its mounting state. In this resistor 10, a resistor 11 made of a resistive metal material is fixed to a heat radiating substrate 15 such as an aluminum substrate with an insulating adhesive material such as boron nitride or aluminum nitride having good thermal conductivity. The resistor 11 is made of a resistive metal material such as a Cu—Ni alloy, a Ni—Cr alloy, or a Cu—Mn alloy. The thickness is about 0.1 to 0.5 mm, and the vertical and horizontal dimensions are about 10 mm × 10 mm to 20 mm × 20 mm. This resistor 11 provides a resistor 10 having a low resistance value of about 1 mΩ.

  The heat dissipation substrate 15 has, for example, dimensions of about 15 mm in length, 25 mm in width, and about 1 to 2 mm in thickness, so that a high power capacity of about 10 W can be obtained. As the heat dissipation substrate 15, a material such as Cu can be used in addition to the aluminum substrate. The heat dissipating substrate 15 has an opening 16 and can be fixed to the heat sink 18 with a mounting screw 19 as shown in FIG. This further increases the power capacity.

  The lower edge of the resistor 11 is provided with base portions 11a, 11b, 11c, and 11d that are convex portions, and lead terminals 12a, 12b, 12c, and 12d made of a highly conductive metal material are provided at the lower ends of the base portions. The upper end part is joined by thermal diffusion joining. Here, the lead terminals 12a, 12b, 12c, and 12d are made of a highly conductive metal material such as Cu, Cu alloy, Ni, Ni alloy, Au, Au alloy, Al, Al alloy, or the like.

  Here, thermal diffusion bonding is a combination of cold rolling, in which a resistance metal material and a highly conductive metal material are rolled while applying pressure at room temperature, and heat treatment at a high temperature of several hundred degrees Celsius or higher. The constituent atoms of the material and the highly conductive metal material are thermally diffused to each other, and a mechanically strong bonded state is obtained. In this joined state, the electrical contact resistance is low, and an electrically favorable joined state can be obtained.

  The resistor 11 is separated from the resistor 11x by the trimming groove 13, whereby the approximate value of the resistance value is adjusted. That is, by adjusting the position of the trimming groove 13 in the illustrated vertical direction, it is possible to adjust the approximate value of the resistance value such as 1 mΩ, 2 mΩ, and 3 mΩ. A trimming groove 17 for fine adjustment of the resistance value is formed in the resistor 11. Thereby, the resistance value is finely adjusted accurately with an accuracy of 1%, for example.

  This resistor 10 includes four lead terminals 12a, 12b, 12c, and 12d, and the two outer terminals 12a and 12d function as current terminals and are connected to the detection current wirings 21 and 21 as shown in FIG. Is done. The inner two lead terminals 12b and 12c function as voltage detection terminals and are connected to the voltage detection wirings 22 and 22, respectively. The voltage detection wires 22 and 22 are connected to a voltage detector (not shown), and the voltage generated in the resistor 11 due to the current flowing between the lead terminals 12a and 12d is detected by the lead terminals 12b and 12c.

  In this resistor 10, the trimming groove 13 for roughly adjusting the resistance value is provided in parallel with the current flow direction, that is, in parallel with the longitudinal direction of the resistor 11. A substantially parallel current distribution is formed in the body 11 along the longitudinal direction of the resistor 11. As a result, a resistor having a small parasitic inductance and a small aging (ΔR) resistance value can be obtained.

  Upper portions of the resistor 11, the resistor 11x, and the lead terminals 12a, 12b, 12c, and 12d are covered and protected by a protective film 20 made of a resin coating material. As the resin coating material, polyimide resin, epoxy resin, polyester resin, acrylic resin, fluorine resin, silicon resin, or the like is used.

  According to the resistor 10, the lower end portions of the base portions 11a, 11b, 11c, and 11d of the resistor are joined to the upper end portions of the lead terminals 12a, 12b, 12c, and 12d by the thermal diffusion bonding at the joining portion 14. As described above, the joint 14 having high reliability and stability both mechanically and electrically can be obtained. The widths of the resistor base portions 11a, 11b, 11c, and 11d are the same as the widths of the lead terminals 12a, 12b, 12c, and 12d. This is easy because, as will be described later, the resistance metal plate constituting the resistor 11 and the highly conductive metal plate constituting the lead terminal are first subjected to thermal diffusion bonding at the respective edges and then subjected to punching by pressing or the like. Further, the width of the resistor base and the width of the lead terminal can be made the same size.

  Next, the manufacturing method of the resistor of this invention is demonstrated with reference to FIG. 3A and FIG. 3B. First, as shown in FIG. 3A (a), a resistance metal plate made of a resistance metal material such as a Cu—Ni alloy, a Ni—Cr alloy, or a Cu—Mn alloy having a thickness of about 0.1 to 0.5 mm. 31 and a highly conductive metal plate 32 made of a highly conductive metal material such as Cu, Cu alloy, Ni, Ni alloy, Au, Au alloy, Al, Al alloy having a thickness of about 0.2 mm. prepare. Then, the resistance metal plate 31 and the highly conductive metal plate 32 are thermally diffused and bonded to each other at the side edge portions, so that the resistance metal plate 31 and the high conductivity metal plate 32 are mechanically connected at the respective edges. A composite material plate 33 is formed which is also electrically bonded firmly.

  Here, in the heat diffusive joining, the side edge portions of the resistance metal plate and the highly conductive metal plate are overlapped (a1), or the taper portions are provided to each other (a2), and then joined by cold rolling first. To do. Then, by performing heat treatment at a high temperature of several hundred degrees Celsius or higher, the constituent atoms of the resistance metal material and the highly conductive metal material are thermally diffused to each other, and a good bonded state is formed both mechanically and electrically. That is, in the joint portions 14 and 14a, the bonding force between both the metal plate materials 31 and 32 is strong because of thermal diffusion bonding, and a joint surface that is strong against thermal stress, mechanical stress, and electrical stress is obtained.

  Next, as shown in FIG. 3A (b), in order to form a lead terminal, for example, a punching process is performed by a press. The lead terminals 12a, 12b, 12c, and 12d are formed by a single punching process. This punching process is performed not only on the joint 14 of the resistance metal plate 31 and the highly conductive metal plate 32 but also on the resistance metal plate 31, that is, so as to remove a part. Thereby, the lead terminals 12a, 12b, 12c, and 12d made of a highly conductive metal material can be completely electrically separated.

The resistance value of the resistor is determined by the width L of the resistor 11. Some resistors metal sheet 31 by performing a punching process by a press to remove, it is possible to form the initial width L ₁ of the resistor 11. By this punching process, convex base portions 11a, 11b, 11c and 11d are provided at the lower end edge of the strip-shaped resistance metal plate 31, and the upper ends of the lead terminals 12a, 12b, 12c and 12d made of a highly conductive metal material are the above-mentioned base portions. A composite material plate 33a bonded to the lower end portion of the substrate by thermal diffusion bonding is formed.

Next, the distortion of the punching process by a press or the like is removed by heat treatment. This is performed, for example, by leaving it for several hours in an inert gas atmosphere such as N ₂ (nitrogen) gas. As a result, the processing distortion due to the press or the like is eliminated, and a resistor having stability and reliability preferable as a current detection resistor can be obtained as described later.

  Next, as shown in FIG. 3A (c), the composite material plate 33a is joined to the belt-like aluminum substrate 35 using an insulating adhesive. As the insulating adhesive, an adhesive made of an insulating material using boron nitride, aluminum nitride or the like having good thermal conductivity is preferable.

  Next, as shown in FIG. 3B (d), the individual resistive elements 11 are cut and separated from the strip-shaped resistive metal plate 31 by mechanical polishing using, for example, sandpaper. In this mechanical polishing, when a thin metal foil is used as the resistor, sandblasting, laser beam processing, or the like can be used. Alternatively, the individual resistive elements 11 may be cut and separated from the strip-shaped resistive metal plate 31 by etching.

Next, as shown in FIG. 3B (e), trimming grooves 13 are formed by mechanical polishing, and the resistance value is roughly adjusted. As described above, the trimming groove 13 is arranged in parallel to the longitudinal direction of the resistor 11 to separate the resistor 11 into two regions 11 and 11x. Thus, the resistor width L ₂ from the initial width L ₁ of the resistor 11 the approximate value of the predetermined resistance value is obtained are formed. Normalized initial width L ₁ from a plurality of example 1 M.OMEGA, it is possible to obtain 2 M [Omega, the resistor width L ₂ corresponding to the approximate value of the desired resistance value, such as 3 milliohms.

  Since the current to be detected flows in the longitudinal direction of the resistor 11, the trimming groove 13 is formed in parallel with the current flow direction, and the resistance value is roughly adjusted without forming a trimming groove across the current flow direction. It can be carried out. Thereby, it is possible to provide a resistor having a low parasitic inductance and capable of withstanding overload. Further, if necessary, the trimming groove 17 perpendicular to the current flow direction can be formed by laser trimming or the like, and the resistance value can be finely adjusted. Thereby, for example, a precision-grade current detection resistor adjusted to an accuracy of 1% is obtained.

  Next, as shown in FIG. 3B (f), the protective film 20 made of a resin coating material covers and protects the upper portions of the resistors 11, 11x and the lead terminals 12a, 12b, 12c, 12d. As the resin coating material, it is preferable to use a polyimide resin, an epoxy resin, a polyester resin, an acrylic resin, a fluorine resin, a silicon resin, or the like. These resin coating materials are applied by potting or the like and heated and cured to form the protective film 20.

  Next, as shown in FIG. 3B (g), the strip-shaped aluminum substrate 35 is cut, for example, by press work, and separated into individual resistors. Thus, the resistor 11 resin-sealed by the protective film 20 to the heat dissipation substrate 15 made of an aluminum substrate, and the high conductivity that protrudes from the end of the heat dissipation substrate are joined to the base end of the resistor. The resistor 10 having lead terminals 12a, 12b, 12c, and 12d made of a conductive metal material is completed.

  Thereafter, solder plating is applied to the lead terminals 12a, 12b, 12c, and 12d as necessary. As the solder material, Sn—Pb solder or lead-free solder is used. Furthermore, it is shipped as a product through processes such as marking, measurement, and inspection.

  FIG. 4 shows an example of data of the effect of the heat treatment after the punching by the press or the like. As a sample, the size of the resistor 11 is 5 mm × 2.5 mm, and the resistance value is 2 mΩ. The test is a 170 ° C. high temperature standing test, the horizontal axis is the standing time (h), and the vertical axis is the resistance value change ΔR (%).

  In the figure, the ■ mark indicates that there is no heat treatment, and the resistance value R changes by about 2 to 3% as the standing time (h) elapses. On the other hand, the mark ● shows a heat treatment at 200 ° C. for 5 hours in a nitrogen atmosphere after press working. In the same manner, the asterisks are heat-treated at 200 ° C. for 3 hours in a nitrogen atmosphere. In addition, the ▲ mark shows a heat treatment at 150 ° C. for 10 hours under a nitrogen atmosphere. Any of these heat treatments shows that the resistance value change ΔR generated with the passage of the standing time in the high-temperature standing test is about 0.5% or less and is extremely stable. Therefore, it can be seen that by performing heat treatment at 150 to 200 ° C. for about 3 to 10 hours after punching by pressing, processing distortion due to punching is removed and electrical stability is remarkably improved.

  Normally, these low-current resistors for current detection are used at respective rated powers based on product specifications at temperatures of -40 ° C to 150 ° C. The 170 ° C. high temperature standing test is a test for predicting the durability of a component by performing accelerated evaluation of heat resistance by applying heat beyond the operating temperature range. As predicted from the results of this test, reliability in actual use uses a highly stable resistance metal material as a resistor, and a lead terminal made of a highly conductive metal material is joined to this by thermal diffusion bonding. Therefore, according to the resistor of the present invention, it can be seen that good resistance value stability is ensured.

  In addition, although one Embodiment of this invention was described so far, it cannot be overemphasized that this invention is not limited to the above-mentioned embodiment, and may be implemented with a different form within the range of the technical idea.

(A) is a partial see-through | perspective view which shows the resistor of one Embodiment of this invention, (b) is sectional drawing of the part of a resistor and a lead terminal. It is a perspective view which shows the example of the mounting state of the said resistor. (A)-(c) is a figure which shows the manufacturing process of the resistor of this invention, (a1) (a2) is with respect to the longitudinal direction of the resistance metal plate material and highly conductive metal plate material in the process of (a). FIG. Further, (c1) is a cross-sectional view showing a state in which a composite material plate having lead terminals is bonded to the aluminum substrate 35. (D)-(g) is a figure which shows the manufacturing process of the continuation of the manufacturing process in FIG. 3A. It is a graph which shows an example of the reliability test result of the resistor manufactured by the said manufacturing process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Resistor 11a, 11b, 11c, 11d Base 11, 11x Resistor 12a, 12b, 12c, 12d Lead terminal 13 Trimming groove | channel 14, 14a Joint part 15 Heat radiation board | substrate 16 Opening 17 Trimming groove | channel 18 Heat sink 20 Protective film 21 Detection current Supply wiring 22 Voltage detection wiring 31 Resistance metal plate material 32 Highly conductive metal plate materials 33 and 33a Composite material plate material 35 Aluminum substrate L ₁ Initial width L ₂ Resistance body width R Resistance value ΔR Resistance value change

Claims (6)

A heat dissipation substrate;
A resistor made of a resistive metal plate fixed to the heat dissipation substrate with an insulating material;
Four bases which are convex portions provided on the lower edge of the resistor ;
It joined to each of said base under an end portion, provided with four of the lead terminals made of a highly conductive metal material projecting from the lower end portion of the heat radiating board,
The ends of the lead terminals are joined to the base end of the resistor by thermal diffusion bonding, respectively , and the width of the lead terminal and the width of the base of the resistor are the same,
Two resistors outside the four lead terminals function as current terminals, and two inside terminals function as voltage detection terminals . The resistor according to claim 1, wherein the resistance metal plate is made of a Cu—Ni alloy, a Ni—Cr alloy, or a Cu—Mn alloy.   The resistor according to claim 1, wherein the heat dissipation substrate is an aluminum substrate. Form a strip-shaped composite material plate in which a resistance metal plate and a highly conductive metal plate are joined by thermal diffusion bonding at each side edge portion,
A part of the strip-shaped composite material plate is punched so as to cover the resistance metal plate , and four convex bases are formed at the lower edge of the resistance metal plate by a single punching process . form forms a lead terminal comprised of four highly conductive metal at its end,
Adhering the strip-shaped composite material plate to the strip-shaped heat dissipation substrate using an insulating adhesive,
The resistance metal plate material portion in which the lead terminals made of the four highly conductive metals are formed from the strip-shaped composite material plate material is separated into individual resistors,
Adjust the resistance value of the resistor,
A method of manufacturing a resistor, wherein the strip-shaped heat dissipation substrate is divided into individual resistors by dividing.   The method for manufacturing a resistor according to claim 4, wherein a heat treatment is performed after the lead terminal portion is formed on the composite material plate by punching.   5. The method of manufacturing a resistor according to claim 4, wherein the resistance value is adjusted by roughly adjusting a resistance value by providing a trimming groove parallel to a longitudinal direction of the resistor. 6.

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