US-12620521-B2 - Coil and method for producing a coil

US12620521B2US 12620521 B2US12620521 B2US 12620521B2US-12620521-B2

Abstract

In an embodiment a coil includes a tube comprising a tube wall composed of an electrically conductive material, wherein the tube wall has an inductive portion in which a gap is arranged that shapes the tube wall so the tube wall forms a helix in the inductive portion, and wherein the tube wall has two contact portions, each contact portion forming an electrical terminal.

Inventors

Stephan Bühlmaier
FELIPE JEREZ GALDEANO
Joachim NASSAL
Anneliese DRESPLING
Gerhard Proks
Herbert Lux

Assignees

TDK ELECTRONICS AG

Dates

Publication Date: 20260505
Application Date: 20200214
Priority Date: 20190215

Claims (20)

1 . A coil comprising: an inductive portion in which a helix is formed by a gap in a tube wall of a tube, the tube wall being composed of an electrically conductive material; two contact portions forming electrical terminals, each contact portion being formed from the tube wall; and two connecting portions formed from the tube wall, each connecting portion connecting one of the two contact portions to the inductive portion, wherein each of the contact portions has two arms pointing oppositely along a direction perpendicular to a longitudinal axis of the helix, wherein the arms are planar in a plane parallel to the longitudinal axis of the helix, and wherein each connecting portion is shorter in the direction perpendicular to the longitudinal axis of the helix than the respective arms along an entire length in the direction perpendicular to the longitudinal axis of the helix, allowing positioning the coil on a printed circuit board along the entire lengths of the arms.
2 . The coil according to claim 1 , further comprising a core.
3 . The coil according to claim 1 , wherein the helix is embedded in a plastic.
4 . The coil according to claim 3 , wherein the plastic is mixed with magnetic powder, magnetic particles or another magnetic material.
5 . The coil according to claim 1 , wherein the coil has an E-shaped pot (EP) core.
6 . The coil according to claim 1 , wherein the helix has an outer diameter of between 0.2 mm and 50 mm, inclusive.
7 . The coil according to claim 1 , wherein each contact portion has a flat surface forming a solderable terminal.
8 . A module comprising: at least two coils according to claim 1 , wherein the two coils are arranged in a common housing.
9 . A method for producing the coil according to claim 1 , the method comprising: providing the tube with the tube wall; creating the gap in the tube wall; shaping at least two portions in the tube wall thereby forming the two contact portions and the two connecting portions; and planarizing the contact portions to form the planar contact portions.
10 . The method according to claim 9 , further comprising using a laser process to create the gap and to shape the contact portions.
11 . The method according to claim 9 , further comprising removing a region of the tube wall thereby forming a recess in the contact portion of the tube.
12 . The method according to claim 11 , wherein the recess in the contact portion of the tube and the gap in the inductive portion are created jointly in a single step.
13 . The method according to claim 11 , further comprising planarizing a region in the contact portion of the tube wall that was not removed.
14 . The method according to claim 9 , wherein creating the gap comprises: firstly creating a coil string so that a plurality of inductive portions are arranged along the tube and so that the gap is created in each inductive portion thereby forming the helix in the tube wall in a respective inductive portion, and secondly singulating the coil string between two adjacent inductive portions in each case so that a contact portion is formed that forms an electrical terminal to the two adjacent inductive portions.
15 . The method according to claim 14 , wherein the coil has an E-shaped pot (EP) core.
16 . The method according to claim 14 , further comprising creating a plurality of coil strings, and embedding the plurality of coil strings in a plastic, wherein the coil strings are arranged parallel to each other.
17 . The method according to claim 16 , further comprising arranging cores in the coil strings.
18 . The method according to claim 16 , wherein the plastic is mixed with magnetic powder, magnetic particles or another magnetic material.
19 . The method according to claim 16 , further comprising singulating the coil strings transversely and/or parallel with respect to a central axis of the coil strings.
20 . A method for producing modules, wherein each module has at least two coils in a common housing, wherein each of the coils is the coil according to claim 1 , the method comprising: creating at least two coil strings comprising a plurality of inductive portions in each of which the gap is created that shapes the tube wall in a respective inductive portion to form the helix, a contact portion between two adjacent inductive portions in each case and a connection portion between the contact portion and the inductive portion in each case; planarizing the contact portions to form planar contact portions; arranging the coil strings in parallel; embedding the coil strings in a plastic, which forms the housing; and singulating the coil strings connected by the plastic, along separation lines that run transverse to a central axis of the coil strings to form the modules, wherein the contact portion, following singulation of the coil string, forms an electrical terminal to the two adjacent inductive portions in each case.

Description

This patent application is a national phase filing under section 371 of PCT/EP2020/053963, filed Feb. 14, 2020, which claims the priority of German patent application 102019103895.2, filed Feb. 15, 2019, each of which is incorporated herein by reference in its entirety. TECHNICAL FIELD The invention relates to a coil, having a tube composed of conductive material, and to a method for producing the coil. BACKGROUND In the context of the miniaturization of electrical circuits, there is great interest in the provision of small inductive components that have low power loss, high current carrying capacity and a reliable, long service life. In the case of wire coils, in particular, a weak point may be the connection of the wire to a contact element that is required for external contacting. The connection, which is usually realized by means of welded joints, or soldered joints, may have an at least slightly increased resistance due to the use of an alloy that contains copper, tin or nickel, or due to contamination with oxygen. If the contacting is not realized properly, the resistance may also be considerably higher. This may result in a high transition resistance, which causes a high power loss. This may also result in an increased thermal load at this point, which in harmless cases may result in a failure of the coil or, in serious cases, in a fire. SUMMARY Embodiments provide a coil that has improved characteristics. Further embodiments provide a manufacturing method for a coil. There is proposed a coil, which has a tube comprising a tube wall composed of an electrically conductive material, wherein the tube has an inductive portion in which there is arranged, in the tube wall, a gap that shapes the tube wall in the inductive portion to form a helix, and wherein the tube has two contact portions in each of which the tube wall is shaped to form an electrical terminal. A tube may be described as an elongate, hollow body having an opening that extends from a first end of the body, through the entirety of the body, to a second end that is opposite to the first end. The tube may be symmetrical relative to its central axis, the central axis extending from the mid-point of a base area at the first end to the mid-point of a base area at the second end. In one embodiment, the tube may have a circular, oval or rectangular cross-section. Other cross-sections are also possible. A helix may be described as a helical structure. In particular, the helix may realize turns of the coil. The tube may have, in particular, a helical gap in the tube wall, whereby the turns of the coil are formed from the tube. The tube is composed of a conductive material. The term conductive material refers to materials having a conductivity of above 104 S/m, but in particular materials having a conductivity of above 105 S/m or above 106 S/m. Materials having a very high conductivity, for example metals such as copper, aluminum, silver or gold may be suitable for this purpose. Industrial steels, such as carbon steel, high-grade steel, alloy steel or tool steel, may also be suitable as a starting material for the tube. The tube comprises the inductive portion and at least one contact portion. Due to the helix formed by the gap, the inductive portion may form an inductance. The inductive portion and the contact portion are realized as a single piece from a material of the tube wall. Thus, no connection means such as, for instance, solder, are required for connecting the inductive portion to the contact portion. Rather, the inductive portion and the contact portion can be formed by appropriate structuring of the tube wall while remaining connected to each other by the tube material. The coil has the advantage that no internal connection points are required for connecting an inductor to a terminal. Rather, the inductive region and the contact region may be realized integrally. The coil has a lower total resistance than a coil that requires internal connection points for connecting an inductor to a terminal. Moreover, the absence of internal contactings also eliminates the thermal as well as mechanical stress that would otherwise occur at the possible internal contactings, thereby reducing the fault susceptibility of the coil. For this purpose, the tube does not have to be round in cross-section, but may be, for example, oval, square, rectangular, polygonal, square with rounded corners, rectangular with rounded corners or polygonal with rounded corners. A square cross-section offers the advantage of optimal utilization of an available installation space for a given height, or width. Depending on the application for which the coil is intended, the base area of the tube may be planar, i.e. the extents of the tube that span the base area may be large compared to the extent over a height, and the height may be small. Or the tube may have a small base area, but a considerable height. If the coil is fitted, for example, on a printed circuit board that is moun