Production method for an electrical resistance element and corresponding resistance element

Abstract

The invention relates to a production method for an electrical resistance element (for example a shunt) with the following steps: —providing a resistance alloy in powder form, and—forming the resistance element from the powdered resistance material. The invention also relates to a correspondingly produced resistance element.

Claims

1. A method of manufacturing an electrical resistor element, comprising the following steps: a) providing a powdery resistance alloy which is a resistance alloy in powder form, and b) forming the resistor element from the powdery resistance alloy by multi-component metal powder injection molding, wherein the following components of resistor are joined together to form a green part: (i) the resistor element which is made of the powdery resistance alloy, and (ii) at least two connection parts made of powdery conductor material.

2. The method of manufacturing according to claim 1, further comprising the following steps: a) mixing at least one of the powdery resistance alloy and the powdery conductor material with a binder to form a feedstock before molding, b) debinding the green part to a brown part after molding, whereby the binder is at least partially removed from the green part, c) sintering the brown part to the finished resistor element, d) reworking of the finished resistor element, and e) joining together the finished resistor element with the at least two connection parts.

3. The method of manufacturing according to claim 1, wherein the method further comprises mixing at least one of the powdery resistance alloy and the powdery conductor material with a binder to form a feedstock of the resistance alloy before molding, and the feedstock of the resistance alloy contains the following constituents: a) 50-80 weight percent of the resistance alloy and b) 20-50 weight percent of organic components.

4. The method of manufacturing according to claim 1, wherein the method further comprises a step of reworking the resistor element by a correction of a resistance value of the resistor element.

5. The method of manufacturing according to claim 1, wherein the method further comprises a step of joining together a finished resistor element with the at least two connection parts by one of the following joining methods: a) welding, b) soldering, or c) sintering.

6. The method of manufacturing according to claim 1, wherein the method further comprises mixing at least one of the powdery resistance alloy and the powdery conductor material with a binder to form a feedstock of the resistance alloy before molding, and the binder contains at least one of the following materials: a) polyamide, b) polyoxymethylene, c) polycarbonate, d) styrene-acrylonitrile copolymer, e) polyimide, f) natural wax and oil, g) thermoset, h) cyanates, i) polypropylene, j) polyacetates, k) polyethylenes, l) ethylene vinyl acetates, m) polyvinyl alcohols, n) polyvinyl chlorides, o) polystyrene, p) polymethyl methacrylates, q) aniline, r) water, s) mineral oil, t) agar, u) glycerol, v) polyvinyl butyryl, w) polybutyl methacrylate, x) cellulose, y) oleic acid, z) phthalate, aa) kerosene wax, ab) wax, ac) ammonium, ad) polyacrylate, ae) diglyceride stearates and oleates, af) glyceryl monostearates, ag) isopropyl titanates, ah) lithium stearates, ai) monoglycerides, aj) formaldehydes, ak) octyl acid phosphates, al) olefin sulphonates, am) phosphate ester, an) stearic acid, and ao) zinc stearates.

7. The method of manufacturing according to claim 1, wherein the powdery resistance alloy contains copper or nickel as the main component.

8. The method of manufacturing according to claim 1, wherein the powdery resistance alloy contains the following alloy components: a) 0.01-95.0 weight percent copper, b) 0.01-80.0 weight percent nickel, c) 0.01-30.0 weight percent manganese, d) 0.001-5.0 weight percent tin, e) 0.001-22.0 weight percent chromium, f) 0.001-5.0 weight percent aluminum, g) 0.001-2.0 weight percent silicon, h) 0.001-1.5 weight percent of iron; and/or i) not more than 1.0 weight percent of other alloying elements.

9. The method of manufacturing according to claim 1, wherein the powdery resistance alloy contains the following alloying constituents: a) 50.0-55.0 weight percent copper, b) 42.0-46.0 weight percent nickel, c) 0.5-2.0 weight percent manganese, and d) not more than 1.5 weight percent of other alloying elements.

10. The method of manufacturing according to claim 1, wherein the powdery resistance alloy contains the following alloying constituents: a) 81.0-89.6 weight percent copper, b) 10.0-14.0 weight percent manganese, c) 0.4-4.0 weight percent nickel; and d) not more than 1.0 weight percent of other alloying elements.

11. The method of manufacturing according to claim 1, wherein the powdery resistance alloy contains the following alloying constituents: a) 60.0-69.0 weight percent copper, b) 23.0-27.0 weight percent manganese, c) 8.0-12.0 weight percent nickel; and d) not more than 1.0 weight percent of other alloying elements.

12. The method of manufacturing according to claim 1, wherein the powdery resistance alloy contains the following alloying elements: a) 88.0-92.5 weight percent copper, b) 6.0-8.0 weight percent manganese, c) 1.5-3.0 weight percent tin, and d) not more than 1.0 weight percent of other alloying elements.

13. The method of manufacturing according to claim 1, wherein the powdery resistance alloy contains the following alloying constituents: a) 62.0-81.4 weight percent nickel, b) 16.0-22.0 weight percent chrome, c) 2.0-4.0 weight percent aluminum, d) 0.4-2.0 weight percent silicon, e) 0.1-5.0 weight percent manganese, f) 0.02-3.0 weight percent copper, g) 0.1-1.0 weight percent iron; and h) not more than 1.0 weight percent of other alloying elements.

14. The method of manufacturing according to claim 1, wherein a) the resistor element has an electrical resistance value with a temperature coefficient of less than 50 ppm/K measured between 20° C. and 60° C., and b) the resistor element has an electrical resistance value with a long-term drift of less than 10%, and c) the resistance alloy has a specific electrical resistance of less than 20.Math.10.sup.−7 Ωm; and d) the conductor material has a specific electrical resistance of less than 5.Math.10.sup.−7 Ωm, and e) the conductor material has a lower specific electrical resistance than the resistance alloy, and f) the resistance alloy has a thermoelectric emf with respect to copper in the thermoelectric series of voltages of less than ±5 mV/100 K.

15. The method of manufacturing according to claim 1, comprising the following step: combining different resistance layers in parallel and/or in series connection to achieve an optimization of the electrical properties.

16. The method of manufacturing according to claim 1, comprising the following step: combining different materials to form the resistance layer in parallel and/or in series connection in order to optimize the mechanical properties.

17. The method of manufacturing according to claim 1, comprising the following step: combining different materials to form the resistance layer in parallel and/or in series connection in order to optimize the thermal properties.

18. The method of manufacturing according to claim 1, further comprising the following step molding heat sinks onto the resistor element.

19. The method of manufacturing according to claim 18, wherein the heat sinks are cooling fins.

20. The method of manufacturing according to claim 1, further comprising the following step: molding electrical connecting elements onto the resistor element.

21. The method of manufacturing according to claim 20, wherein the electrical connecting elements are plug contacts.

22. The method of manufacturing according to claim 1, wherein the resistor element is a coaxial resistor.

23. The method of manufacturing according to claim 1, wherein the resistor element is a current sense resistor.

24. A resistor which is manufactured by the manufacturing method in accordance with claim 1.

25. The resistor according to claim 24, wherein the resistor is a current sense resistor.

26. The resistor according to claim 24, comprising a) a first connection part made of the powdery conductor material for introducing an electric current into the resistor, b) a second connection part made of the powdery conductor material for diverting the electric current from the resistor, and c) the resistor element made of the powdery resistance alloy, which is arranged in the direction of current flow between the first connection part and the second connection part and through which the electric current flows.

27. A method of manufacturing an electrical resistor element, comprising the following steps: a) providing a powdery resistance alloy which is a resistance alloy in powder form; b) forming the electrical resistor element from the powdery resistance alloy; and c) mixing at least one of the powdery resistance alloy and a powdery conductor material with a binder to form a feedstock before molding, wherein the binder contains the following components: i) 10-50 weight percent polyamide, ii) 40-80 weight percent of fatty alcohol, and iii) 2-20 weight percent of organic acid.

28. A method of manufacturing an electrical resistor element comprising the following steps: a) providing a powdery resistance alloy which is a resistance alloy in powder form; b) forming the electrical resistor element from the powdery resistance alloy; and c) mixing at least one of the powdery resistance alloy and a powdery conductor material with a binder to form a feedstock before molding, wherein the binder contains the following components: i) 50 to 96 weight percent of one or more polyoxymethylene homopolymers or polyoxymethylene copolymers; ii) 2 to 35 weight percent of one or more polyolefins; and iii) 2 to 40 weight percent of poly-1,3-dioxepan or poly-1,3-dioxolane or mixtures thereof.

29. A method of using a resistor element comprising the following steps: a) providing a powdery resistance alloy which is a resistance alloy in powder form, b) forming a resistor element from the powdery resistance alloy by multi-component metal powder injection molding, wherein the following components of a resistor are joined together to form a green part: i) the resistor element which is made of the powdery resistance alloy, and ii) least two connection parts made of a powdery conductor material, and c) using the resistor element.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other advantageous further developments of the invention are marked in the dependent claims or are explained in detail below together with the description of the preferred examples of the invention using the figures. They show:

(2) FIG. 1 shows a perspective view of a conventional current sense resistor manufactured in a conventional way,

(3) FIG. 2 shows a top view of a resistor element produced by the manufacturing method according to the invention,

(4) FIG. 3 is a flowchart illustrating the manufacturing method by two-component metal injection molding according to the invention,

(5) FIG. 4 shows another flow chart to illustrate the manufacturing method according to the invention using metal injection molding,

(6) FIGS. 5A and 5B show different perspective views of a coaxial resistor manufactured by the method of manufacture according to the invention,

(7) FIGS. 6A and 6B different perspective views of a multiple bent current sense resistor, and

(8) FIGS. 7A and 7B different perspective views of a resistor according to the invention with molded-on cooling fins.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(9) FIG. 1 shows a perspective view of a conventional current sense resistor 1, which is used for current measurement according to the well-known four-wire technique and is cut from a composite material strip as described in EP 0 605 800 A1.

(10) The current sense resistor 1 essentially consists of a resistor element 2 made of a resistance alloy (e.g. Manganese®) and two connection parts 3, 4 made of a conductor material (e.g. copper), whereby the resistor element 2 is connected along its longitudinal edges to the connection parts 3 and 4 respectively by two weld seams 5, 6.

(11) In the two connection parts 3, 4 there are holes 7, 8, which serve as connecting elements to facilitate the electrical contact.

(12) A disadvantage of this known current sense resistor 1 is the fact that the shape is limited by the cross-section of the underlying composite material strip, so that not any arbitrary shapes of the current sense resistor are possible.

(13) FIG. 2 shows a top view of a resistor element 9 according to the invention, which was produced by metal injection molding (MIM: Metal Injection Molding) and can therefore take on a variety of shapes.

(14) The drawing shows that the resistor element 9 has joining surfaces 10 in order to be able to connect the resistor element 9 with connection parts.

(15) Furthermore, the drawing shows a sintered resistance material 11, which can take on different shapes.

(16) At the side of the resistor element 9 there can be areas 12 for the adjustment of the resistance value.

(17) Furthermore, the drawing shows elliptical areas 13 for contacting measuring terminals.

(18) In the following, the flow chart as shown in FIG. 3 is explained, which is an embodiment of the manufacturing method according to the invention.

(19) In a first step S1, a resistance alloy in powder form is first provided.

(20) In a second step S2, the powdery resistance alloy is then mixed with a binder to form a so-called feedstock.

(21) In a step S3, copper is provided in powder form for the connection parts.

(22) The powdery copper is then also mixed with a binder in a step S4 to form a feedstock.

(23) In a further step S5, a two-component metal injection molding of the feedstock of the powdery copper and the feedstock of the powdery resistive alloy into a resistor (green part) with one resistor element and two connection parts is then carried out.

(24) In a next step S6 the resistor (green part) is then debound, i.e. the binder is at least partially removed, so that a so-called brown part is produced.

(25) In a further step S7, the brown part is then sintered.

(26) Finally, in a step S8, the resistor can be reworked, e.g. to correct the resistance value.

(27) In the following, the flow chart as shown in FIG. 4 is explained, which provides an alternative example of the manufacturing method according to the invention.

(28) In a first step S1, a resistance alloy in powder form is prepared again.

(29) In a second step S2, the powdery resistance alloy is then mixed with a binder to form a feedstock.

(30) In a further step S3, the feedstock of the powdery resistance alloy is then injection molded into a resistor element (green part).

(31) In the next step S4 the green part is debound to a brown part, i.e. the previously added binder is at least partially removed.

(32) In the next step S5, the brown part of the resistor element is then sintered.

(33) In a further step S6, the resistor element is then joined together with the copper connection parts to form a resistor.

(34) Finally, in a step S7, the resistor can be reworked, e.g. to correct the resistance value.

(35) The embodiment in FIG. 4 differs from the embodiment in FIG. 3 in that the connection parts in the embodiment in FIG. 4 are attached after metal injection molding, whereas the connection parts in the embodiment in FIG. 3 are molded in the two-component metal injection molding process.

(36) In the following, the example shown in FIGS. 5A and 5B is described. These drawings show a coaxial resistor 14 with two connection parts 15, 16 made of a conductor material (e.g. copper) and a resistor element 17 made of a resistance alloy inserted between them.

(37) The manufacturing method in accordance with the invention allows a large scope of design regarding the outer shape of the coaxial resistor 14, which can have complex curvatures.

(38) In the following, the embodiment according to FIGS. 6A and 6B is described. The drawings show different perspective views of a current sense resistor 18 with connectors 19, 20 made of a conductor material (e.g. copper) and a resistor element 21 made of a resistance alloy inserted in between.

(39) The manufacturing method according to the invention allows complex bends of the current sense resistor 18.

(40) In the following, we will now finally describe the embodiment according to FIGS. 7A and 7B.

(41) The drawings show a current sense resistor 22, which was manufactured according to the manufacturing method according to the invention and has two connection parts 23, 24 and a resistor element 25.

(42) In addition, the drawings show two voltage measuring contacts 26, 27 for measuring the voltage dropping along the resistor element 25.

(43) Finally, the drawings show cooling fins 28-31, which are molded onto the resistor element 25 and dissipate heat loss during operation.

(44) The invention is not limited to the preferred embodiments described above. Rather, a large number of variants and modifications are possible, which also make use of the inventive idea and therefore fall within the scope of protection. In particular, the invention also claims protection for the subject matter and the features of the sub-claims independently of the claims referred to in each case and in particular without the features of the main claim. The invention thus comprises a large number of inventive aspects which enjoy protection independently of one another.

LIST OF REFERENCE SIGNS

(45) 1 Current sense resistor 2 Resistor element 3, 4 Connection parts 5, 6 welding seams 7, 8 Drillings 9 Resistor element 10 Joining surfaces 11 Resistance material 12 Areas for adjusting the resistance value 13 Elliptical areas for contacting measurement connections 14 Coaxial resistor 15, 16 Connection parts 17 Resistor element 18 Current sense resistor 19, 20 Connection parts 21 Resistor element 22 Current sense resistor 23, 24 Connection parts 25 Resistor element 26, 27 Voltage measuring contacts 28-31 Cooling fins