Ceramic core inductor component and ceramic core inductor component subassembly

Abstract

The utility model relates to a ceramic core inductor component and a ceramic core inductor component subassembly. A ceramic core inductor component includes a wire coil disposed around a portion of a ceramic core having a dielectric constant of 8 or less and electrically connected to a conductive pad disposed on a corresponding mount, where the ceramic core inductor component has improved performance due to a higher quality factor and a higher self-resonant frequency.

Description

Technical Field

[0001] This invention generally relates to non-magnetic inductor components, and more specifically to ceramic core inductor components for radio frequency (RF) applications and configurable for mounting on printed circuit boards. Background Technology

[0002] Ceramic core inductor components are typically integrated with increasingly smaller circuits and host devices for certain radio frequency (RF) applications, where reduced size and performance are paramount. Such applications include handheld communication devices, laptops, military and commercial aircraft, and spacecraft. For these and other applications, ceramic core inductors generally exhibit better performance than ferrite core inductors. This improved performance is primarily attributed to the low permeability of the ceramic core. Ceramic core inductors store energy more efficiently, exhibiting a higher quality (Q) factor, higher self-resonant frequency (SRF), and better temperature stability than ferrite core inductors. However, further improvements to the performance of ceramic core inductor components are still needed. Utility Model Content

[0003] One aspect of this application relates to a ceramic core inductor component, the ceramic core inductor component comprising: a ceramic core, the ceramic core including a ceramic body portion located between a first ceramic support and a second ceramic support, the ceramic core having a dielectric constant of less than 8; a conductive coil disposed around the ceramic body portion; and a first terminal and a second terminal, the first terminal being disposed on a first surface of the first ceramic support and the second terminal being disposed on a second surface of the second ceramic support, wherein a first end of the conductive coil is electrically connected to the first terminal and a second end of the conductive coil is electrically connected to the second terminal.

[0004] The ceramic core inductor component is a surface-mountable device, wherein the first terminal and the second terminal each include conductive pads, and each of the first ceramic support and the second ceramic support is positioned such that, when the ceramic core inductor component is mounted on the mounting surface, the axis of the conductive coil is oriented parallel to the mounting surface.

[0005] The ceramic core inductor component further includes a non-conductive shank, which is fastened to the ceramic core and at least partially covers the conductive coil.

[0006] The ceramic core has a dielectric constant of 6 or less.

[0007] The ceramic core inductor component is a 1μH inductor with a Q factor greater than 50 and a self-resonant frequency greater than 400MHz, with a tolerance of 10% or less.

[0008] The ceramic core inductor component is a 470nH inductor with a Q factor greater than 60 and a self-resonant frequency greater than 550MHz, with a tolerance of 5% or less.

[0009] The ceramic core inductor component is a 12nH inductor with a tolerance of 5% or less, including a Q factor greater than 80 and a self-resonant frequency greater than 3000MHz.

[0010] Another aspect of this application relates to a ceramic core inductor component subassembly, the ceramic core inductor component subassembly comprising: a ceramic core, the ceramic core including a main body portion located between a first support and a second support, the ceramic core having a dielectric constant of less than 8; a first conductive terminal disposed on an end face of the first support; and a second conductive terminal disposed on an end face of the second support.

[0011] The first conductive terminal and the second conductive terminal each include a base layer on the end face of the corresponding support and an outermost conductive layer covering the base layer.

[0012] The base layer includes a silver layer, and the outermost conductive layer includes a tin layer.

[0013] The first conductive terminal and the second conductive terminal each further include an intermediate conductive layer between the base layer and the outermost conductive layer.

[0014] The intermediate conductive layer includes a nickel layer or a copper layer.

[0015] The first conductive terminal and the second conductive terminal each include a silver-platinum-palladium alloy layer deposited on the end face of the corresponding support.

[0016] The ceramic core is pressed ceramic, and the first conductive terminal and the second conductive terminal cover the sides of the corresponding first support and second support.

[0017] The ceramic core has a dielectric constant of 6 or less. Attached Figure Description

[0018] The objects, features, and advantages of this invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. The drawings depict only representative embodiments and implementations and are not intended to limit the application of this invention or its teachings.

[0019] Figure 1 This is a perspective view of a representative ceramic core inductor component.

[0020] Figure 2 yes Figure 1 Side view of the inductor component.

[0021] Figure 3 yes Figure 2 A partial cross-sectional side view of the inductor component.

[0022] Figure 4 yes Figure 2 A bottom view of the inductor component.

[0023] Figure 5 It is a representative ceramic core blank.

[0024] Figure 6 yes Figure 5 End view of the ceramic core blank.

[0025] Figure 7 It is an optional ceramic core blank.

[0026] Figure 8 It includes electrical terminals formed on the support. Figure 7 A side view of the ceramic core blank.

[0027] Figure 9 yes Figure 8 A bottom view of the ceramic core blank.

[0028] Figure 10 The diagram shows a comparison of the Q factor versus frequency for a 1 microhenry (μH) ceramic core inductor component with respect to existing technology and the present invention.

[0029] Figure 11 Show Figure 10 Comparative inductance-frequency curves of a 1μH ceramic core inductor component.

[0030] Figure 12 The diagram shows a comparison of the Q-factor versus frequency curves of the existing technology and the present invention's 470 nm Henry (nH) ceramic core inductor components.

[0031] Figure 13 Show Figure 12 Comparative inductance-frequency curves of a 470nH ceramic core inductor component.

[0032] Figure 14 The diagram shows a comparison of the Q-factor versus frequency curves of the existing technology and the present invention's 12nm Henry (nH) ceramic core inductor components.

[0033] Figure 15 Show Figure 14 Comparative inductance-frequency curves of a 12nH ceramic core inductor component.

[0034] Those skilled in the art will understand that the accompanying drawings are for simplicity and clarity and therefore may not be drawn to scale and may not include well-known features; the order in which actions or steps occur may differ from the representative order described; some or all of these actions or steps may be performed simultaneously unless otherwise specified; and the terms and expressions used herein have the meanings understood by those skilled in the art, unless the different meanings are specifically attributed to them. Detailed Implementation

[0035] This invention generally relates to ceramic core inductor components for radio frequency (RF) applications with improved performance. The ceramic core inductor components described herein are suitable for filters, low-noise amplifiers (LNAs), power supplies, oscillators, impedance matching circuits, servo systems and other controllers, and various other circuits. Such circuits are found in space and terrestrial communication systems, radar systems, and automotive, medical, industrial and consumer electronics products, as well as many other systems and applications.

[0036] The ceramic core inductor components described in this article typically include a conductive coil wound around a ceramic core. Figures 1 to 3 In this example, a representative inductor component 100 includes a ceramic core 110 supporting a conductive coil 120 wound around a body portion of the ceramic core between a first ceramic support and a second ceramic support. The conductive coil includes ends electrically connected to corresponding electrical terminals (also referred to herein as “terminals”) integrated with the ceramic core. These and other aspects of the ceramic core inductor component are further described herein.

[0037] The ceramic core inductor components described herein have a dielectric constant (κ) selected to reduce parasitic losses (e.g., parasitic capacitance) and thus improve inductor performance. The improved performance is characterized by a higher quality (Q) factor and a higher self-resonant frequency (SRF) compared to comparable prior art ceramic core inductors. The Q factor is the ratio X of the inductor's inductive reactance to its resistance. L / R L In this context, inductive reactance is a function of inductance L and parasitic capacitance. A higher SRF can be attributed to lower parasitic capacitance.

[0038] Dielectric constant is a material property considered in the design of capacitors, not inductors. However, the inventors of the ceramic core inductors described herein have recognized that the self-resonant frequency (SRF) of a ceramic core inductor has an inverse relationship with the dielectric constant (κ) of the ceramic core, and that appropriate selection of the ceramic core based on the κ value can improve inductor performance. Representative ceramic core inductor components with κ values ​​of 8 or less, as described herein, are shown to have improved quality (Q) factor and SRF compared to prior art ceramic core inductors with higher κ values. Representative ceramic core inductors and their ceramic compositions are described herein.

[0039] exist Figures 5 to 6 In this example, a representative ceramic core blank 122 includes a body portion 112 extending radially beyond a peripheral portion 113 of the body portion between a first flange 114 and a second flange 116. Each flange or a portion thereof includes a mounting surface that forms a support for mounting on a host mounting surface 102. Figure 5 In this embodiment, the first support 124 and the second support 126 each include corresponding end faces 115 and 117, on which electrical terminals may be positioned as further described herein. Alternatively, the terminals may be located on a portion of the ceramic core that is separate from the first support 124 and the second support 126.

[0040] Both the main body and the radial flange can have polygonal cross-sections, for example... Figure 6 The diagram shows a square cross-section. In other embodiments, both the body portion and the flanges may have circular cross-sections, and each flange may be provided with one or more flat surfaces for surface mounting or for electrical terminals as described herein. Alternatively, the body portion may have a circular cross-section, and the flanges may have polygonal cross-sections. In other embodiments, the ceramic core blank does not have flanges extending radially outward from the body portion.

[0041] exist Figure 7 In this alternative ceramic core blank 128, a body portion 112 is located between a first flange and a second flange. This body portion includes corresponding supports (e.g., a first support 124 and a second support 126) having corresponding end faces 115 and 117, respectively. The alternative ceramic core blank 128 has a quadrilateral polygonal cross-section, and the supports extend beyond a peripheral portion 113 of at least one side of the body portion.

[0042] Figures 5 to 9 The ceramic core may include other shapes and configurations and may be formed prior to firing by isostatic pressing or mechanical pressing or molding, as well as other known and future ceramic forming operations.

[0043] The composition of the ceramic core composition typically depends on the desired performance characteristics of the inductor component. The ceramic core may include one or more of the following: calcium strontium tungstate, magnesium silicate, magnesium aluminate, magnesium aluminum silicate, calcium silicate, zinc silicate, aluminum silicate, or silicon dioxide, or combinations of two or more thereof, alone or in combination with other elements or compounds. Each of the aforementioned elements or compounds has a dielectric constant (κ) of 8 or less. Aluminum silicate, magnesium aluminum silicate, and silicon dioxide each have a dielectric constant of 6 or less. Magnesium aluminum silicate and silicon dioxide have a dielectric constant of 5 or less.

[0044] In a specific embodiment, the ceramic core comprises more than five percent (5%) of each of the following: magnesium aluminum silicate; magnesium silicate; and magnesium aluminate. In a more specific embodiment, the ceramic core comprises more than 15% magnesium aluminum silicate, more than 5% magnesium aluminate, and more than 10% magnesium silicate by weight, wherein the ceramic core has a dielectric constant of 6 or less. In these and other embodiments, the ceramic core may optionally include other components, such as fillers or additives.

[0045] In an alternative embodiment, the ceramic core comprises, by weight, each of the following: between 41% and 54% silicon dioxide; between 27% and 38% aluminum oxide; and between 10% and 17% magnesium oxide, wherein the ceramic core has a dielectric constant of 5 or less. Other components of the alternative composition may include up to 12% tin oxide, up to 7% titanium oxide, and up to 2% lanthanum oxide, as well as other additives. These or other additives in the ceramic core composition may slightly increase the dielectric constant, possibly to a value greater than 5.

[0046] The conductive coil includes ends electrically connected to corresponding electrical terminals integrated with the ceramic core. The terminals can be configured as metallized or other conductive pads located on the corresponding support or other parts of the ceramic core, depending on how the component will be electrically integrated with a host device (e.g., mounted on a host device). Figures 8 to 9 In the middle, the first terminal 130 and the second terminal 132 are formed on the end faces of the first support and the second support (e.g., Figure 5 and Figure 7 (As shown above). Figures 2 to 4 Different views of electrical terminals (e.g., first terminal 130 and second terminal 132) are shown. Figures 2 to 3 as well as Figures 8 to 9 As shown, each electrical terminal can optionally surround and cover a portion of the sidewall of the corresponding support to increase the contact area between the terminal and the ceramic core. Figures 8 to 9 In this configuration, terminals (e.g., first terminal 130 and second terminal 132) on the end face of the support form the mounting surface. With this configuration, the ceramic core inductor component can be electrically and mechanically integrated with a host device (e.g., a PCB) via reflow or wave soldering or some other electrical and mechanical integration operation.

[0047] In other embodiments, electrical terminals may be located on surfaces of the ceramic core other than the mounting surface. With this configuration, the mounting surface of the ceramic core inductor component can be mechanically secured to the host device (e.g., by bonding material), and electrical terminals located on different portions of the ceramic core can be electrically integrated with the host device via wire bonding, solder, or some other conductor connection member.

[0048] In one embodiment, the electrical terminal includes a conductive base plated with one or more conductive outer layers. The base may include silver or some other highly conductive metal or alloy; for example, the base may include a silver layer or an alloy layer. In one embodiment, the base includes a silver (Ag) frit deposited onto a selected portion of the ceramic core (e.g., a mount surface). Other conductors may alternatively be used. The base may be applied to the ceramic core during impregnation or other known or future operations.

[0049] The outermost conductive layer can be formed directly on the base layer or on the intermediate conductive layer. The outermost conductive layer composition can be selected to improve other terminal properties, such as solderability (e.g., improved wetting) and oxidation resistance. In one embodiment, the outermost conductive layer is tin (Sn) or a tin-based alloy (e.g., SnPb), for example, the outermost conductive layer comprises a tin layer or a tin-based alloy layer. Other conductors may also be used. The conductive outermost layer can be applied to the base layer or intermediate layer during electroplating operations and other known or future processes.

[0050] In some embodiments, an intermediate conductive layer is located between the base layer and the outermost conductive layer to protect the base layer. For example, the intermediate layer may have a higher melting temperature than the base layer. In one embodiment, the intermediate layer comprises copper (Cu), for example, the intermediate layer comprises a copper layer. Alternatively, the intermediate layer may be nickel (Ni) or some other conductor or alloy; for example, the intermediate layer may comprise a nickel layer or an alloy layer. The conductive intermediate layer can be applied to the base layer in an electroplating operation and other known or future processes.

[0051] In other embodiments, the electrical terminals comprise a silver-platinum-palladium (AgPtPd) alloy (e.g., an AgPtPd alloy layer) deposited onto selected portions of the ceramic core. Other platinum group metals or alloys may also be used. Representative low-melting-point solders developed for surface-mount ceramic component terminals comprising such alloys include solder type Sn62, etc. The electrical terminals may be applied to the ceramic core through dipping or other known or future operations.

[0052] The conductive coil may comprise a solid or hollow core wire. In one embodiment, the conductive coil is formed from solid copper wire and other good conductors. In another embodiment, the conductive coil comprises a non-copper (e.g., aluminum) inner core plated with copper or silver. The wire may optionally include a non-conductive outer sheath (e.g., enamel) for electrical insulation. The wire may be wound around the ceramic core during a coil winding operation after terminal formation. The ends of the conductive coil may be electrically connected to corresponding terminals by spot welding or other soldering operations, soldering, wire bonding, or some other electrical integration operation. In some embodiments, the ends of the conductive coil are flattened prior to electrical integration. Figure 4In the conductive coil 120, each end 121 and 123 is electrically integrated with a corresponding terminal (e.g., first terminal 130 and second terminal 132) located on the end face of the corresponding support.

[0053] The ceramic core inductor components described herein can be configured for surface mounting or other integration with host equipment. Figure 2 In this configuration, the first and second supports are positioned such that the axis of the conductive coil is parallel to the mounting surface 102 of the host when the ceramic core inductor component 100 is mounted on the mounting surface. The dimensions of the first support 124 and the second support 126 are set to space the conductive coil from the mounting surface when the ceramic core inductor component is mounted on the mounting surface.

[0054] In some implementations, the ceramic core inductor component includes a non-conductive shank to accommodate automated pick-and-place of components and other component handling operations. The non-conductive shank covers at least a portion of the inductor component. Figures 2 to 4 In this embodiment, the ceramic core inductor component 100 includes a non-conductive shank 136 located on a portion of the ceramic core opposite to the support. In other embodiments, the non-conductive shank covers all portions of the inductor component except for the electrical terminals. The non-conductive shank may comprise epoxy, plastic, resin, or other non-conductive materials. After the coil is assembled around the ceramic core, the non-conductive shank may be applied by dipping, spraying, or other coating operations.

[0055] Representative dimensions of the ceramic core inductor components described herein are shown in Table I below. "Dimensions" refers to the length and width of the mounting surface area of ​​the component. The dimensions disclosed below are typical for surface-mount components and are not intended to limit the scope of this invention. In other embodiments, depending on the electrical and performance requirements of the intended use case and integration constraints, the ceramic core inductors described herein may be larger or smaller than the dimensions depicted below.

[0056]

[0057] Table I

[0058] The dimensions in the first column, “Size Measurements,” of Table I are standard package dimensions established by the Joint Electronic Equipment Committee (JEDEC) standards organization, which are readily understood by those skilled in the art. More information can be found at https: / / forum.digikey.com / t / standard-package-sizing-for-two-terminal-smds / 5104. The dimensional measurements in the other tables below have the same meaning and will not be described again.

[0059] The inductance of a ceramic core inductor component is a function of the coil geometry (e.g., the number of turns, length, and cross-sectional area) and the permeability of the ceramic core and adjacent materials. Therefore, the range of inductance values ​​for ceramic core inductor components described herein is typically constrained by the component's size and the properties of the ceramic core and surrounding materials. Typical minimum inductance values ​​for representative ceramic core inductor component sizes in Table I range from 0.8 nH to 3 μH. However, inductance can be larger or smaller, depending on electrical and performance requirements and integration constraints of the intended use case.

[0060] Table II below shows the measurement characteristics of a prior art 1μH ceramic core inductor and a 1μH ceramic core inductor with a dielectric constant of 5 or less according to the present invention. Both inductors have an inductance of 1μH and a tolerance of 10% or less. The inductor according to the present invention has a higher minimum Q factor and maximum Q factor, as well as a higher SRF, than the prior art inductor. Dimensions indicate the length and width dimensions of the component (i.e., 2.5mm × 2.0mm).

[0061]

[0062] Table II

[0063] Figure 10 The graph shown in Table II illustrates the measured Q-factor versus frequency for the 1μH ceramic core inductor. The higher Q-factor of the ceramic core inductor of this invention indicates higher efficiency (i.e., reduced parasitic losses) than prior art inductors, and thus improved performance. Figure 11 The graph of measured inductance versus frequency for the 1μH ceramic core inductor shown in Table II is presented.

[0064] Table III below shows the measurement characteristics of a prior art 470nH ceramic core inductor and a 470nH ceramic core inductor according to the present invention with a dielectric constant of 5 or less. Both inductors have an inductance of 470nH and a tolerance of 5% or less. The inductor according to the present invention has a higher minimum Q factor and maximum Q factor, as well as a higher SRF, than the prior art inductor. Dimensions indicate the length and width dimensions of the component (i.e., 2.5mm × 2.0mm).

[0065]

[0066] Table III

[0067] Figure 12 The measured Q-factor versus frequency curve of the 470nH ceramic core inductor depicted in Table III is shown. The higher Q-factor of the ceramic core inductor of this invention indicates higher efficiency (e.g., reduced parasitic losses) than prior art inductors, and thus improved performance. Figure 13The graph shown in Table III depicts the measured inductance versus frequency curve of the 470nH ceramic core inductor.

[0068] Table IV below shows the measurement characteristics of a prior art 12nH ceramic core inductor and a 12nH ceramic core inductor according to the present invention with a dielectric constant of 5 or less. Both inductors have an inductance of 470nH and a tolerance of 5% or less. The inductor according to the present invention has a higher minimum Q factor and maximum Q factor, as well as a higher SRF, than the prior art inductor. Dimensions indicate the length and width dimensions of the component (i.e., 2.5mm × 2.0mm).

[0069]

[0070] Table IV

[0071] Figure 14 The measured Q-factor versus frequency curve of the 12nH ceramic core inductor depicted in Table IV is shown. The higher Q-factor of the ceramic core inductor of this invention indicates higher efficiency (e.g., reduced parasitic losses) than prior art inductors, and thus improved performance. Figure 15 A graph showing the measured inductance values ​​for the 12nH ceramic core inductor described in Table IV is presented.

[0072] Although the present invention and its presently preferred mode have been described in a manner that establishes ownership and enables those skilled in the art to make and use the invention, and are hereby considered to be the best mode thereof, it will be understood and recognized that many equivalents of the representative embodiments described herein exist, and various modifications and variations may be made thereto without departing from the scope and spirit of the present invention, which is not limited to the described embodiments but rather to the appended claims and their equivalents.

Claims

1. A ceramic core inductor component, characterized in that, The ceramic core inductor component includes: A ceramic core, the ceramic core comprising a ceramic body portion located between a first ceramic support and a second ceramic support, the ceramic core having a dielectric constant of less than 8; A conductive coil, the conductive coil being disposed around the ceramic body portion; and A first terminal and a second terminal, wherein the first terminal is disposed on a first surface of the first ceramic support, and the second terminal is disposed on a second surface of the second ceramic support. The first end of the conductive coil is electrically connected to the first terminal, and the second end of the conductive coil is electrically connected to the second terminal.

2. The ceramic core inductor component according to claim 1, characterized in that, The ceramic core inductor component is a surface-mountable device, wherein the first terminal and the second terminal each include conductive pads, and each of the first ceramic support and the second ceramic support is positioned such that, when the ceramic core inductor component is mounted on the mounting surface, the axis of the conductive coil is oriented parallel to the mounting surface.

3. The ceramic core inductor component according to claim 2, characterized in that, The ceramic core inductor component further includes a non-conductive shank, which is fastened to the ceramic core and at least partially covers the conductive coil.

4. The ceramic core inductor component according to any one of claims 1 to 3, characterized in that, The ceramic core has a dielectric constant of 6 or less.

5. The ceramic core inductor component according to claim 4, characterized in that, The ceramic core inductor component is a 1μH inductor with a tolerance of 10% or less, and the inductor has a Q factor greater than 50 and a self-resonant frequency greater than 400MHz.

6. The ceramic core inductor component according to claim 4, characterized in that, The ceramic core inductor component is a 470nH inductor with a tolerance of 5% or less, and the inductor has a Q factor greater than 60 and a self-resonant frequency greater than 550MHz.

7. The ceramic core inductor component according to claim 4, characterized in that, The ceramic core inductor component is a 12nH inductor with a tolerance of 5% or less, and the inductor has a Q factor greater than 80 and a self-resonant frequency greater than 3000MHz.

8. A ceramic core inductor component subassembly, characterized in that, The ceramic core inductor component sub-assembly includes: A ceramic core, the ceramic core comprising a main body portion located between a first support and a second support, the ceramic core having a dielectric constant of less than 8; A first conductive terminal is disposed on the end face of the first support; and The second conductive terminal is disposed on the end face of the second support.

9. The ceramic core inductor component subassembly according to claim 8, characterized in that, The first conductive terminal and the second conductive terminal each include a base layer on the end face of the corresponding support and an outermost conductive layer covering the base layer.

10. The ceramic core inductor component subassembly according to claim 9, characterized in that, The base layer includes a silver layer, and the outermost conductive layer includes a tin layer.

11. The ceramic core inductor component subassembly according to claim 10, characterized in that, The first conductive terminal and the second conductive terminal each further include an intermediate conductive layer between the base layer and the outermost conductive layer.

12. The ceramic core inductor component subassembly according to claim 11, characterized in that, The intermediate conductive layer includes a nickel layer or a copper layer.

13. The ceramic core inductor component subassembly according to claim 8, characterized in that, The first conductive terminal and the second conductive terminal each include a silver-platinum-palladium alloy layer deposited on the end face of the corresponding support.

14. The ceramic core inductor component subassembly according to claim 8, characterized in that, The ceramic core is pressed ceramic, and the first conductive terminal and the second conductive terminal cover the sides of the corresponding first support and second support.

15. The ceramic core inductor component subassembly according to any one of claims 8 to 14, characterized in that, The ceramic core has a dielectric constant of 6 or less.

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