An electrical feedthrough component is described.
A ceramic, multiple-layer capacitor is known from the publication DE 101 36 545 A1. Another ceramic component and also a method for its production are known from the publication DE 101 32 798 C1.
Described herein is an electrical feedthrough component that has a high capacitance with a low surface area, and a method for the manufacture thereof.
An electrical feedthrough component with a base body is described, in which first inner electrodes and second inner electrodes are arranged, wherein the first inner electrodes are connected to each other via a first outer electrode that extends in a peripheral direction of the base body, and wherein second inner electrodes are connected to each other in a conductive way via a through connection extending in the axial direction of the base body. The feedthrough component is for surface mounting.
The component can achieve noise suppression in a signal line over a wide frequency range. The component may be a feedthrough filter for suppressing noise in signal lines of high-frequency circuits, for example, as a broadband filter for IT applications. The component can be integrated, e.g., in a plug or a power supply.
The component has a high capacitance, low parasitic inductance, high current, especially in the feedthrough direction, and small dimensions. High-frequency noise signals are damped with high insertion loss. The high insertion loss at high frequencies is traceable back to the low value of the parasitic inductance.
The through connection is conductively connected to second outer electrodes, which are arranged at least partially on opposing end surfaces of the base body arranged perpendicular to the axial direction.
Alternately arranged first and second inner electrodes form an electrode stack. The first and second inner electrodes are insulated electrically from each other. The first inner electrodes are arranged perpendicular to the first outer electrode. The second inner electrodes are arranged parallel to the second outer electrode.
The second inner electrodes are connected to each other via the through connection. In contrast, the edges of the second inner electrodes are spaced apart from the circumferential surface of the base body.
The edges of the first inner electrodes reach up to the circumferential surface of the base body. A recess for realizing the through connection is provided in each of the first inner electrodes. The recess in the first internal electrode may be an opening or a hole.
The through connection is arranged essentially parallel to the surface area of the base body. The through connection may be concealed in the base body. The through connection can be constructed as a solid rod. Alternatively, the through connection can be constructed in the base body as an opening with metallized walls.
The first outer electrode is arranged on the circumferential surface of the base body and may surround the base body on all sides.
In an embodiment, the base body is cubical. The surface of the base body, which is provided for connection to the circuit board, is designated as its bottom side or the main surface. Two opposing side surfaces of the base body, on which the second outer electrodes are arranged, are designated as its end sides. The end sides can also be designated as a base surface and a top surface of the base body. The remaining four surfaces form a circumferential surface of the base body.
A symmetrical construction of the base body is advantageous. The feedthrough component may have a mirror-symmetric construction relative to a plane passing through the center of the base body and arranged perpendicular to the axis of the through connection.
The feedthrough component can have a mirror-symmetric construction relative to a plane which is arranged parallel to the base surface and perpendicular to the end surfaces of the base body, and in which the axis of the through connection lies.
The feedthrough component can have a mirror-symmetric construction relative to a plane which is arranged perpendicular to the base surface and perpendicular to the end surfaces of the base body, and in which the axis of the through connection lies.
An “active” area of the base body is designated as a functional unit, which is formed by a stack of dielectric layers and first and second inner electrodes arranged between them. The first and second inner electrodes are here arranged in a stack alternating one above the other. A functional unit may be used as a capacitor or a varistor. In one variant, the feedthrough component can have more than just one functional unit.
The component may have two second outer electrodes, which are arranged at least partially on opposite end surfaces of the base body, for each functional unit. In one variant, the through connection is guided through the base body and connects the two second outer electrodes to each other.
In another variant, the ends of the through connection are spaced apart from the second outer electrode. In this case, the through connection is connected on its two ends to at least one third internal electrode whose edges contact a part of the second outer electrode arranged on the circumferential surface of the base body. This results in a good connection of the through connection and the second inner electrode to the second outer electrode. Several third inner electrodes may be connected to each end of the through connection.
In one variant, several functional units, which are each constructed essentially like the functional unit described above, are arranged in one base body. Here, different stacks of first and second inner electrodes are each associated with a separate signal path.
At least one separate second outer electrode, e.g., two separate second outer electrodes, are associated with the second inner electrodes. The first inner electrodes of all of the stacks may be connected to at least one common first outer electrode.
Other through connections can be arranged, in the base body each of which connects at least two of the first inner electrodes to each other electrically. These through connections may be arranged between two adjacent stacks of inner electrodes.
The first outer electrode may be a ground connection and the second outer electrode may be a signal connection.
The feedthrough component may be a chip for surface mounting on an external circuit board, i.e., as a component with SMD contacts (SMD=Surface Mounted Device). An SMD contact, e.g., at least one part of the first outer electrode, can be arranged on the bottom side of the base body facing the circuit board.
However, an SMD contact could also be arranged on a side surface of the base body. For example, the second outer electrode provided as an SMD contact is arranged at least partially on an end side of the base body. The second outer electrode can completely top the end side of the base body or only part of this surface. Here the end surfaces of the base body may lack the first outer electrode.
The second outer electrode could project past the edges, e.g., past the lower and/or the upper edge of the end side associated with it. It is advantageous for a part of the second outer electrode to be arranged on the bottom side of the base body.
In one variant, at least one area of the circumferential surface of the base body is not covered by the first outer electrode. The circumferential surface of the base body may be divided in the axial direction into two peripheral or belt-shaped edge regions and an also peripheral or belt-shaped center region between these edge regions. The center region of the base body is covered by the outer electrode, wherein the edge regions are not covered by the first outer electrode.
The feedthrough component with the through connection may be produced in a multiple-layer method.
This method comprises the following steps:
A) Edge regions of the base body are constructed each with a first opening filled with a conductive paste,
B) An intermediate region of the base body is constructed with first and second inner electrodes arranged in this intermediate region and with a second opening filled with a conductive paste that conductively connects the second inner electrodes to each other and that is guided through a recess provided in the first inner electrodes, wherein the first inner electrodes are constructed so that their edges are exposed,
C) The intermediate region is oriented between the edge regions such that the first openings and the second opening are arranged along one axis and form a through connection,
D) A first outer electrode contacting the edges of the first inner electrodes is created at least on the surface of the intermediate region,
E) Second outer electrodes conductively connected to the through connection are created on the end sides of the base body.
The steps A) and B) can be performed simultaneously. The steps D) and E) can be performed in one processing step.
The base body may be sintered before steps D) and E). The first outer electrode and the second outer electrodes may each be applied with a conductive paste onto a sintered body and fired.
Each of the mentioned regions of the base body may be generated in a multiple-layer process.
In order to form a part of the through connection, a continuous opening filled with a metallic paste is constructed in each edge region so that it passes through the respective edge region and appears at a surface of the edge region provided as an end surface of the base body. Later, for forming a second outer electrode on this surface e.g., only after sintering of the base body—an electrically conductive paste, which monolithically joins to the end side of the through connection when the outer electrode is fired, is deposited at least in the region of the exposed end of this opening.
In order to create an edge region, e.g., ceramic layers with continuous holes, which are formed in these layers and are filled by an electrically conductive paste, are stacked one above the other so that their holes are arranged one above the other along an axis—the longitudinal axis of the future through connection—and pressed together. These holes each form a part of the through connection. The ceramic layers may be constructed independently of each other, then stacked one above the other and pressed together so that they connect to each other and reach a designated thickness.
In order to create the intermediate region, ceramic layers are also created with continuous holes formed in these layers and filled by a conductive paste. Conductive surfaces are created between the ceramic layers, e.g., through screen printing, optionally with the use of masks, for forming first and second inner electrodes.
The terminally situated layers of the intermediate region may be ceramic layers. The ceramic layers are arranged one above the other so that one hole is arranged above the other. The stack formed in this way is pressed together and arranged between the edge regions. All of the regions are pressed together again, which forms the base body. By pressing the edge region or the intermediate region of the base body, parts of the through connection formed by filled holes are connected to each other, or an opening passing through the base body and filled with the conductive paste is formed by pressing together all of the base body regions.
The base body is sintered. In this way, in one variant the conductive paste located in the continuous opening is converted into a solid through connection.
In one variant, the conductive paste can be partially removed from the continuous opening before sintering of the base body, e.g., through suction. The inner walls of the opening, however, remain covered with the conductive paste, so that a hollow feedthrough with metallized walls is produced when the base body is sintered.
Instead of using the steps A) to C) on the layer series of the first edge region, it is possible in one variant of the method to create the layer sequence of the intermediate region, and on this series create the layer series of the second edge region.
In one variant, the edge regions are each constructed with at least one third internal electrode whose edges each intersect the surface of the edge region corresponding to the circumferential surface of the base body. A part of the through connection is formed in a part of the edge region facing towards the intermediate region, as described above. For several third inner electrodes, a via hole is constructed in the ceramic layers arranged in-between them in order to form another part of the through connection.
In order to form second outer electrodes, in a later processing step a metallic paste is deposited partially on the circumferential surface of the base body, such that it covers the edges of the one or more third inner electrodes. In firing the metallic paste, the second outer electrode is formed, which is monolithically joined to the one or more third internal electrode(s).
Ceramic, e.g., is suitable as the material for the dielectric layers. In one variant, the capacitor ceramic can be, for example, COG, X7R, Z5U, Y5V, HQM, or any other capacitor ceramic. In another variant, the ceramic layers can be formed from varistor ceramic, which contains, e.g., ZnO—Bi, ZnO—Pr, SrTiO3. A feedthrough component constructed as varistor ceramic has filter properties on the one hand, and on the other hand can be used as over-voltage protection, in particular as ESD protection.
The feedthrough component is distinguished by a high ampacity of, e.g., more than 1 A. In one variant, the ampacity equals at least 2 A.
The feedthrough component will now be explained with reference to schematic figures that are not true to scale.
The base body 5 is divided into two “passive” edge regions 51, 52 and an “active” region—the intermediate region 50—arranged between these edge regions. The intermediate region 50 forms the functional unit of the component.
All of the first inner electrodes are connected to a first electrical potential. All of the second inner electrodes are connected to a second electrical potential, such as a reference potential, and are isolated electrically from the first inner electrodes.
The first inner electrodes 1 each represent a conductive surface in which a recess 9, constructed as a hole for example, is provided for realizing a via hole 4. The first inner electrodes 1 are concealed in the base body interior up to their edges. The edges of the first inner electrodes 1 are exposed on the surface or circumferential surface of the base body. A belt-shaped first outer electrode 10, which contacts the edges of the first inner electrodes 1 on all sides, is arranged on the circumferential surface 70 of the base body 5. The first outer electrode 10 may be connected to ground, and is used as shielding for the functional unit.
The second inner electrodes 2 are completely concealed in the base body interior and are spaced apart from the first outer electrode 10 (
On both end sides 61, 62 of the base body 5 there is a second outer electrode 20 that completely covers the corresponding end side. The outer electrode 20 extends past the edges of the end surface 61 or 62, so that parts of these electrodes are arranged on all sides of the circumferential surface 70 of the base body.
The through connection 4 is completely concealed in the interior of the base body. In one variant, the through connection 4 can be constructed as a solid rod.
Alternatively, the through connection 4 can be constructed as a hollow tube, e.g., a continuous opening with metallized internal walls. In one variant, the through connection 4 also passes through the outer electrodes, so that the outer electrodes each have one opening. An electrical conductor, e.g., a wire, can be guided through a thus-constructed through connection from the outside. The electrical conductor may be solidly joined, e.g., soldered, at least at the ends to the through connection. However, it is also possible that a through connection constructed as a hollow tube is closed off at the ends by outer electrodes.
The feedthrough component may be arranged in a signal line, wherein the through connection 4 forms a part of the signal line and the functional unit forms a capacitor or a varistor that is arranged between the signal line and ground.
Shown in
Shown in
In
In a variant not shown here, parts 20a, 20b of the second outer electrode 20 projecting past the end side 61, 62 are eliminated because an outer electrode standing perpendicular to the connection surface of a circuit board is also suitable, in principle, as an SMD contact. In this case, the second outer electrode 20 is arranged completely on the end side.
In a first variant shown in
In a second variant shown in
The third inner electrodes 3 each represent a continuous conductive surface that is concealed in the base body interior up to its edges. The edges of the third inner electrodes 3 are exposed on the circumferential surface of the base body and may form a contact on all sides by the parts 20a, 20b of the second outer electrode 20 arranged on the circumferential surface 70 of the base body 5.
The through connection 4 passes through all of the third inner electrodes 3 up to the last third internal electrode 3, which meets the end of the through connection 4. In this case, the electrical connection between the second inner electrodes 2 and the second outer electrode 20 is first formed by the through connection 4, and second by the third inner electrodes 3 connected in parallel. This type of electrical connection is distinguished by low losses at the joint to the second outer electrodes 20.
According to the embodiment only one third internal electrode, two, or more than three third inner electrodes can be used instead of three third inner electrodes 3 for connecting the through connection 4 to the parts 20a, 20b of the second outer electrode 20 arranged on the circumferential surface 70.
The first end side 61 (base surface) of the base body 5 is located in
Different cross sections of this component are shown in
The functional units are each formed by a stack of dielectric layers and first and second inner electrodes 1, 2 or 1, 2′ arranged between them. The first and the second inner electrodes of a stack are arranged alternately one above the other—in
The feedthrough component according to the second embodiment comprises, as a whole, four functional units, which may all be constructed identically or like the functional unit already explained in
All of the functional units are connected to a common first outer electrode 10. At least one of the first inner electrodes 1 may be constructed so that it is continuous up to the recesses 9, 9′ and connects all of the stacks to each other. In
The cross section shown in
Number | Date | Country | Kind |
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102005022142.4 | May 2005 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/DE2006/000817 | 5/11/2006 | WO | 00 | 5/29/2008 |