Low noise capacitors

Abstract

To provide relatively low noise capacitors for surface mounted applications.SOLUTION: Electro-mechanical vibrations generate audible noise, which are relatively reduced through modifications to MLCC device structures, and / or their mounting interfaces on substrates such as printed circuit boards (PCBs). Different embodiments variously make use of flexible termination compliance so that surface mounting has reduced amplitude vibrations transmitted to the PCB. In other instances, side terminal and transposer embodiments effectively reduce the size of mounting pads relative to a case of a capacitor, or a molded enclosure provides standoff, termination compliance and clamping of vibrations.SELECTED DRAWING: Figure 4A

Description

[Technical field]

[0001] The disclosed technology relates to low noise capacitors and corresponding methodologies. More particularly, the disclosed technology relates to the construction and surface mounting of capacitor devices on substrates such as printed circuit boards (PCBs) to provide both mechanical and electrical connections having relatively low noise characteristics (i.e., electromechanical noise reduction). [Background technology]

[0002] This application claims the benefit of previously filed U.S. Provisional Patent Application No. 62 / 010,488, entitled "LOW NOISE CAPACITORS," filed June 11, 2014, which is incorporated by reference for all purposes.

[0003] High density packaging of electronic components on printed circuit boards and other substrates is common in the electronics industry. Small ceramic surface mount type capacitors with multiple layers have been used for some time in electronic devices such as cell phones, network routers, computers, etc. The manufacturing techniques for such devices must be precise to provide for the greatly reduced size of these devices while still allowing for the desired electrical operating characteristics.

[0004] More recently, it has become desirable to provide additional types of components and various subcircuits in a form mountable on a substrate. Several U.S. patents are directed to various aspects of electronic component manufacturing and mounting techniques. For example, commonly owned U.S. Pat. No. 6,299,433 (Ritter et al., entitled "Multilayer Ceramic RC Device") discloses an RC device including a plurality of first and second ceramic layers interleaved to form a stack. Each of the ceramic layers includes suitable electrode structures of opposite polarity that form the equivalent of a plurality of two-plate capacitors. Known embodiments of multilayer ceramic capacitors (MLCCs) are also shown, for example, in Figures 2 and 3 of commonly owned U.S. Pat. No. 6,299,433 (Pelcak et al., entitled "Capacitor assembly").

[0005] The diversification of modern technological applications has resulted in the need for efficient electronic components and integrated circuits for use therein. Capacitors are fundamental components used for filtering, decoupling, bypassing, and other aspects of such modern applications, which may include wireless communications, high speed processing, networking, circuit switching, and many other applications. The significant increase in speed and packing density of integrated circuits has led to advances in decoupling capacitor technology.

[0006] As high capacitance decoupling capacitors are exposed to the high frequencies of many current applications, their performance characteristics become increasingly important. Because capacitors are the basis of such a wide variety of applications, their precision and efficiency are essential. Thus, there has been focus on many specific aspects of capacitor design to improve the performance characteristics of capacitors.

[0007] Currently, a variety of conventional capacitors are available on the market, each offering a unique combination of performance characteristics that are suitable for a particular application. For example, multi-layer ceramic capacitors (MLCCs) are typically quite effective for frequency filtering applications. It is quite common for these and other specific capacitor types to be used in a single integrated circuit environment. In such cases, different capacitors may be connected in parallel on a printed circuit board (PCB) as individual components. Such an approach requires a relatively large amount of circuit space for each capacitor. This may require a separate mounting pad and

[0008] For some time, the design of various electronic components has been driven by a general industry trend toward miniaturization and ease of incorporation of components into new or existing applications. In view of this, there is a need for smaller electronic components that have superior operating characteristics. For example, some applications require the use of passive devices that exhibit a variety of characteristics including capacitive, inductive, and / or resistive properties or combination assemblies thereof, but the amount of space that such devices may occupy on a circuit board (known as the "real estate"). Circuit boards are severely limited in the amount of space that they occupy. It is important that such devices or combinations be constructed to maximize ease of physical and electrical attachment to such circuit boards while occupying the smallest amount of "real estate" possible. As a result, there is a continuing effort to obtain component miniaturization, orientation efficiency, and other means of conserving space and maximizing board real estate in PCB environments.

[0009] It may also be desirable to improve other capacitor performance characteristics such as ESR (equivalent series resistance), which is the specific resistance of the capacitor.

[0010] Another capacitor characteristic that can affect circuit applications is piezoelectric noise, or electromechanical or acoustic noise, which is common in many packaged MLCC applications. Low-level piezoelectric noise can be generated when the ceramics of a capacitor are exposed to an AC voltage that can induce mechanical vibrations in the capacitor. The inherent properties of ceramic materials convert the mechanical vibrations into generally low-level electrical noise. A significant amount of piezoelectric noise can affect signal quality, especially in high-frequency applications. Therefore, it is often desirable to reduce piezoelectric noise in circuit applications.

[0011] Capacitors deform in response to an applied voltage (electric field) due to the electrostrictive behavior inherent to all dielectric materials, as expressed by the known equation below: Distortion = M ij *electric field 2

[0012] Generally, high dielectric constant materials have high electrostrictive coefficients. The CV (capacitance times voltage) rating is related in part to the volumetric efficiency of the capacitor. In general, the higher the capacitance, the larger the volume of the capacitor. For a given capacitance value, the higher the voltage rating, the larger the volume of the capacitor. Thus, when a capacitor has a "high CV rating," this means that it is volumetrically efficient and exhibits a small physical size compared to other capacitor types. High CV capacitors have evolved to have very thin inner layers, thus providing very high electric field strengths even at modest operating voltages.

[0013] Mechanical strain (vibration) is transferred from the capacitors through the solder terminals to the PCB board. The capacitors act as a sounding instrument, like a drum head. When the capacitor acts as a driver, essentially a drum stick, the main audible noise is therefore generated by vibrations from the PCB and not the capacitor itself.

[0014] The opposite effect can also occur: vibrations on the PCB coupled to the capacitor through the terminals can cause AC ripple voltage on the capacitor. Such an effect is called "microphonics" and can be a problem in special cases.

[0015] Various approaches have previously been offered in an attempt to reduce the electromechanical noise associated with mounted MLCC devices, including, for example, minimizing the amount of solder (for mounting the device on a PCB), rotating the orientation of the MLCC innerlayers parallel to the PCB, using lower K dielectric materials, increasing the standoffs (leads), and Pre-mounting the capacitors on the board (larger non-adjustable) These include increasing the clamping force (to provide active margin) and simply replacing the MLCC devices with different types of devices, such as tantalum capacitors. Such approaches inherently come at a cost, such as, in some cases, increased cost or increased complexity of the MLCC device design or packaging techniques.

[0016] Additional patent citations include U.S. Patent No. 5,399,333 (Winzer et al., entitled "Integrated composite optical fiber array"), which relates to multi-layer structures having associated noise cancellation features. US Patent No. 5,393,633 (Korony et al., entitled "High Frequency Resistor") relating to resistors having flexible termination materials, and US Patent No. 5,393,633 (Korony et al., entitled "High Frequency Resistor") relating to resistors having flexible termination materials. See also US Patent No. 5,393,633 (Korony, et al., entitled "Thin Film Surface Mount Components"), US Patent No. 5,393,633 (Hattori, entitled "Electronic Component"), US Patent No. 5,393,633 (Hattori, entitled "Ceramic Electronic Component and Electronic Device"), and US Patent No. 5,393,633 (Hattori, entitled "Electronic Component").

[0017] The disclosed subject matter generally relates to small electronic components that are surface mounted to larger circuit boards. More particularly, the subject matter may relate to surface mount capacitor devices for use in various applications. According to industry practice, the size of a surface mount component is generally expressed as the number "XXYY", where XX and YY are the length and width in hundredths of an inch (0.0254 cm), respectively. [Prior art documents] [Patent documents]

[0018] [Patent Document 1] U.S. Patent No. 5,889,445 [Patent Document 2] U.S. Patent No. 7,352,563 [Patent Document 3] U.S. Pat. No. 5,629,578 [Patent Document 4] U.S. Pat. No. 8,665,059 [Patent Document 5] US Patent Application Publication No. 2011 / 0090665 [Patent Document 6] US Patent Application Publication No. 2014 / 0016242 [Patent Document 7] US Patent Application Publication No. 2013 / 0299224 [Patent Document 8] US Patent Application Publication No. 2013 / 0284507 Summary of the Invention [Problem to be solved by the invention]

[0019] Various embodiments of capacitor devices and associated assemblies and packaging methodologies therefor have been developed, but no design has emerged that generally encompasses all of the desired characteristics presented below by the subject technology. [Means for solving the problem]

[0020] The presently disclosed subject matter recognizes and resolves some of the above-mentioned problems, as well as other problems related to certain aspects of capacitor devices. Thus, broadly speaking, it is an object of certain embodiments of the presently disclosed technology to provide improved designs for certain capacitor components and component assemblies associated with implementations of surface mountable devices. Broadly speaking, another object is to provide low noise capacitors and related methodologies.

[0021] Another object of the present disclosure is to provide a printed circuit board (PCB) for providing both mechanical and electrical connections having improved relatively low noise characteristics (i.e., electromechanical noise reduction). and the like.

[0022] An aspect of other exemplary embodiments of the present disclosed subject matter provides improved electrical and mechanical coupling of certain surface mount devices to circuits or traces on a printed circuit board on which the device may be mounted for improved noise performance characteristics.

[0023] Yet another aspect of an embodiment of the disclosed subject matter provides enhancements to manufacturing and / or packaging methodologies associated with the use of surface mount type devices.

[0024] It should also be understood that the presently disclosed technology likewise applies to the resulting devices and structures, and corresponding accompanying methodologies, disclosed and / or discussed herein.

[0025] Aspects of yet other embodiments of the presently disclosed subject matter provide compliant termination features for noise reduction aspects. Other embodiments of the presently disclosed subject matter relate to advantageous relocation of terminals of surface mounted capacitors. Still additional embodiments of the presently disclosed subject matter relate to the enclosure of a capacitor, such as in an epoxy case. It should be noted that other embodiments of the presently disclosed subject matter may relate to the pre-mounting of a capacitor on a so-called transposer component or element.

[0026] A further general object is to provide relatively low manufacturing costs combined with relatively improved noise reduction in surface mounted capacitor devices.

[0027] It should be appreciated that certain aspects of the disclosed subject matter may also be applied to discrete active components or their combination with passive components. For example, active combinations including, but not limited to, amplifiers, oscillators, and other functional block assemblies can benefit from the disclosed techniques.

[0028] It is also an object to provide improved devices and / or associated methodologies that result in low noise surface mounted capacitor devices useful, for example, in audio circuits in handheld electronics, automotive electronics, computer disk drives, and in certain industrial, aerospace, and medical applications.

[0029] One exemplary embodiment disclosed herein relates to a surface mountable relatively low noise multilayer ceramic capacitor (MLCC) capacitor assembly. The capacitor assembly preferably comprises a body having a plurality of conductive layers of respective first and second polarities interleaved with a plurality of ceramic layers to form respective pairs of opposing capacitor plates in a stacked arrangement, and respective first and second polarity terminations at opposite ends of the body electrically connected to the first and second polarity conductive layers, respectively, and further comprising a compliant layer for relatively damping vibrations between the capacitor assembly and a surface on which the capacitor assembly is mounted to relatively reduce electromechanical noise.

[0030] In some embodiments, the compliant layer may include a layer of a compliant polymer. In various embodiments, the compliant polymer may include a polymer that is generally conductive, or a conductive polymer that is a silver-polymer layer, or one of a silver, copper, or nickel filled polymer.

[0031] In another alternative embodiment, the surface on which the capacitor assembly is mounted includes a support substrate. In various embodiments, the support substrate may include a printed circuit board and the compliant polymer layer may have a modulus of elasticity generally less than 5 GPa, such that surface mounting of the capacitor assembly reduces amplitude vibration transmitted to the printed circuit board, providing both a mechanical and electrical connection with relatively low noise characteristics.

[0032] In various alternative embodiments, the termination may include a silver polymer on a relatively thin flashing layer and / or the flash layer may include a copper layer, or alternatively, the termination may include a silver polymer on a relatively thin copper flash layer with a layer of plating on the silver polymer layer. In some alternatives, the layer of plating may include nickel-tin plating.

[0033] The presently disclosed subject matter is intended to relate to corresponding and / or related methods as well. One presently disclosed exemplary embodiment relates to a methodology for relatively reducing electromechanical noise associated with a surface mountable multilayer ceramic capacitor (MLCC) capacitor assembly. The exemplary methodology preferably includes providing a body having a plurality of conductive layers of respective first and second polarities interleaved with a plurality of ceramic layers to form respective pairs of opposing capacitor plates in a stacked arrangement, and forming respective first and second polarity terminations at opposite ends of the body electrically connected to the first and second polarity conductive layers, respectively. Additionally, the terminations include a compliant layer for relatively damping vibrations between the capacitor assembly and the surface to which it is mounted to relatively reduce electromechanical noise.

[0034] In some alternatives of the exemplary methodology, the compliant layer may include a layer of a compliant polymer, hi other alternatives, the compliant polymer may include a generally conductive polymer including one of a silver, copper, or nickel filled polymer.

[0035] Variations of the exemplary methodology may further include surface mounting the capacitor assembly on a support substrate including a printed circuit board, such that the surface mounting of the capacitor assembly reduces amplitude vibrations transmitted to the printed circuit board and provides both a mechanical and electrical connection having relatively low noise characteristics.

[0036] In other presently disclosed variations, the termination may include a silver polymer on a relatively thin copper flash layer, or a silver conductive polymer on a relatively thin copper flash layer, with a layer of plating on the silver conductive polymer layer.

[0037] In yet another exemplary embodiment disclosed herein, a surface mountable relatively low noise multilayer ceramic capacitor (MLCC) capacitor assembly preferably comprises a body having a plurality of conductive layers of respective first and second polarities interleaved with a plurality of ceramic layers to form respective pairs of opposing capacitor plates in a stacked arrangement, respective first and second polarity terminations at opposite ends of the body electrically connected to the first and second polarity conductive layers, respectively, and a molded case within which the body is received with the terminations supported on the surface for relatively damping vibrations between the capacitor assembly and a surface to which the capacitor assembly is mounted for relatively reducing electromechanical noise.

[0038] In some variations of the exemplary embodiment, the molded case may include an epoxy case that completely encapsulates the body. In some cases, the conductive layer may be aligned perpendicular to the surface on which the terminations are supported, while in other cases the alignment may be other than perpendicular. In a further variation, the molded case is a land grid array style package on the solder pads of a predetermined size case. In another alternative, the predetermined size case may include the dimensions of a 1206 A-case package, where the dimensions of the 1206 A-case package include the length and width of the case, respectively, expressed in hundredths of an inch (0.0254 cm). As will be appreciated by those skilled in the art, A-case is the industry term for a 1206 size equivalent device. It should be appreciated that the subject matter disclosed is equally applicable to other sizes and arrangements. For example, it may be implemented using a B-case (1210 equivalent size) as well as R- and N-cases (0805 equivalent size). The disclosed subject matter may also be implemented to mount A-, B-, R-, and N-case parts on industry standard mounting pads (1206, 1210, 0805, and 0805, respectively) and also mount the same A-, B-, R-, and N-case parts on mounting pads that are one size smaller (1206, 0805, 0603, and 0603, respectively). This latter method places solder pads under the part (also known as land grid array style) and removes large solder fillets from the ends of the molded capacitors, thereby reducing clamp stresses and vibration coupling from the capacitor to the mounting board.

[0039] In other alternatives, the surface on which the capacitor assembly is mounted may include a support substrate. In some cases, the support substrate may include a printed circuit board, and the molded case may include a molded package having a polymer coating and a lead frame. In some cases, the body may be received with the conductive layers aligned vertically relative to the surface on which the terminations are supported, but in other arrangements, they may be aligned other than vertically to isolate the capacitor strains from the printed circuit board to attenuate device noise by reducing the amplitude of vibrations transmitted to the printed circuit board, thus providing both a mechanical and electrical connection with relatively low noise characteristics.

[0040] In another variation, the termination may comprise nickel-tin plating on a copper film.

[0041] Another disclosed exemplary embodiment relates to a methodology for relatively reducing electromechanical noise associated with a surface mountable multilayer ceramic capacitor (MLCC) capacitor assembly. The exemplary methodology includes providing a body having a plurality of conductive layers of respective first and second polarities interleaved with a plurality of ceramic layers to form respective pairs of opposing capacitor plates in a stacked arrangement, forming respective first and second polarity terminations at opposite ends of the body electrically connected to the first and second polarity conductive layers, respectively, and disposing the body within a molded case with the terminations supported on the surface to relatively damp vibrations between the capacitor assembly and a surface on which the capacitor assembly is mounted to relatively reduce electromechanical noise.

[0042] In the above variations, the molded case may include an epoxy case that completely encapsulates the body. In some cases, the conductive layers may be aligned vertically relative to the surface on which the terminations are supported, while in other arrangements they may be implemented other than vertical. In some other variations, the molded case may include an A-case package that is implemented as a land grid array style package on the solder pads of a pre-determined size case.

[0043] In other alternatives, the surface may include a supporting substrate and / or the supporting substrate may include a printed circuit board and the molded case may include a molded package having a polymer coating and a lead frame. In some cases, the body may be received with the conductive layer aligned perpendicular to the surface on which the terminations are supported, although other arrangements are possible. In the present invention, the capacitor may be implemented other than vertically to isolate the capacitor strain from the printed circuit board to attenuate device noise by reducing the amplitude of vibration transmitted to the printed circuit board, thus providing both a mechanical and electrical connection with relatively low noise characteristics.

[0044] In yet other variations, the termination may include nickel-tin plating on the copper film and / or the length of the termination and the location of its attachment point may be predetermined to further isolate vibrations transmitted from the capacitor assembly to the printed circuit board.

[0045] Another presently disclosed exemplary embodiment relates to a surface mountable relatively low noise multi-layer ceramic capacitor (MLCC) capacitor assembly, preferably comprising a body having a plurality of conductive layers of respective first and second polarities interleaved with a plurality of ceramic layers to form respective pairs of opposing capacitor plates in a stacked arrangement, and respective first and second polarity terminations on opposite sides of the body for relatively reduced support and connection footprint between the capacitor assembly and a surface to which the capacitor assembly is mounted to relatively reduced electromechanical noise and relatively reduced vibration force transmission between the capacitor assembly and a surface to which the capacitor assembly is mounted, the respective first and second polarity terminations being electrically connected to the first and second polarity conductive layers, respectively, with terminations supported on the surface.

[0046] In some variations of the above, the surface on which the capacitor assembly is mounted may include a support substrate and / or the support substrate may include a printed circuit board, such that surface mounting of the capacitor assembly reduces amplitude vibrations transmitted to the printed circuit board and provides both a mechanical and electrical connection having relatively low noise characteristics.

[0047] In other present alternatives, the terminations may include a layer of nickel-tin plating, or may include nickel-tin plating on a copper film, and / or the copper film may include a relatively thick film of copper.

[0048] One presently disclosed example corresponding method may relate to a methodology for relatively reducing electromechanical noise associated with a surface mountable multilayer ceramic capacitor (MLCC) capacitor assembly, the methodology preferably including the steps of providing a body having a plurality of conductive layers of respective first and second polarities interleaved with a plurality of ceramic layers to form respective pairs of opposing capacitor plates in a stacked arrangement; forming respective first and second polarity terminations on opposite sides of the body electrically connected to the first and second polarity conductive layers, respectively; and supporting the terminations on a surface, wherein a relatively reduced support and connection footprint is formed between the capacitor assembly and the surface on which the capacitor assembly is mounted to relatively reduce vibration force transmission between the capacitor assembly and the surface on which the capacitor assembly is supported to relatively reduce electromechanical noise.

[0049] In the alternative, the surface on which the capacitor assembly is supported may include a support substrate and / or the support substrate may include a printed circuit board, such that surface mounting of the capacitor assembly reduces amplitude vibrations transmitted to the printed circuit board and provides both a mechanical and electrical connection having relatively low noise characteristics.

[0050] In other variations, the terminations may include a layer of nickel-tin plating and / or may include nickel-tin plating on a copper film. In some cases, the copper film may include a relatively thick film of copper.

[0051] Yet another presently disclosed exemplary embodiment relates to a surface mountable relatively low noise multilayer ceramic capacitor (MLCC) capacitor assembly, preferably comprising a body having a plurality of conductive layers of respective first and second polarities interleaved with a plurality of ceramic layers to form respective pairs of opposing capacitor plates in a stacked arrangement, respective first and second polarity terminations in the body electrically connected to the first and second polarity conductive layers, respectively, and a transposer mounting pad attached to the capacitor assembly with the transposer mounting pad supported on the surface for relatively reduced support and connection footprint between the capacitor assembly and a surface on which the capacitor assembly is supported to relatively reduce electromechanical noise and relatively reduced vibration force transmission between the capacitor assembly and the surface on which the capacitor assembly is supported.

[0052] In some of the above alternatives, the side of the body facing the surface on which the capacitor assembly is supported may form a capacitor mounting pad, and the capacitor assembly may further include a solder mask between the capacitor mounting pad and the transposer mounting pad.

[0053] In another alternative, the respective first and second polarity terminations may be formed on opposite ends of the body.

[0054] In yet other variations, the surface on which the capacitor assembly is supported may include a support substrate and / or the support substrate may include a printed circuit board, such that surface mounting of the capacitor assembly reduces amplitude vibrations transmitted to the printed circuit board and provides both a mechanical and electrical connection having relatively low noise characteristics.

[0055] In yet another alternative, the terminations may include a layer of nickel-tin plating and / or nickel-tin plating over a copper film.

[0056] In other variations, the area of ​​the transposer mounting pads may be approximately half or less the area of ​​the capacitor mounting pads to effectively reduce the size of the mounting pads for the capacitor assembly.

[0057] Exemplary corresponding and / or related methods may relate to a methodology for relatively reducing electromechanical noise associated with a surface mountable multilayer ceramic capacitor (MLCC) capacitor assembly, the methodology preferably including the steps of providing a body having a plurality of conductive layers of respective first and second polarities interleaved with a plurality of ceramic layers to form respective pairs of opposing capacitor plates in a stacked arrangement, forming respective first and second polarity terminations in the body electrically connected to the first and second polarity conductive layers, respectively, and attaching a transposer mounting pad to the capacitor assembly and supporting the transposer mounting pad on the surface to relatively reduce support and connection footprint between the capacitor assembly and a surface on which the capacitor assembly is supported to relatively reduce vibration force transmission between the capacitor assembly and the surface on which the capacitor assembly is supported to relatively reduce electromechanical noise.

[0058] In the above variations, attaching the transposer mounting pad to the capacitor assembly and supporting the transposer mounting pad on the surface may include pre-mounting the transposer mounting pad to the capacitor assembly prior to supporting the transposer mounting pad on the surface.

[0059] In another alternative, the side of the body facing the surface on which the capacitor assembly is supported may form a capacitor mounting pad, and the methodology may further include providing a solder mask between the capacitor mounting pad and the transposer mounting pad.

[0060] Further alternatively, each first polarity termination and second polarity termination may be formed on opposite ends of the body.

[0061] In another alternative embodiment, the surface on which the capacitor assembly is supported may include a support substrate and / or the support substrate may include a printed circuit board, such that surface mounting of the capacitor assembly reduces amplitude vibrations transmitted to the printed circuit board and provides both a mechanical and electrical connection having relatively low noise characteristics.

[0062] In other variations, the terminations may include a layer of nickel-tin plating and / or nickel-tin plating on a copper film. In other alternatives to the above, the area of ​​the transposer mounting pads may be approximately half or less the area of ​​the capacitor mounting pads to effectively reduce the size of the mounting pads for the capacitor assembly.

[0063] Further objects and advantages of the disclosed subject matter will be set forth in the detailed description herein or will become apparent to those skilled in the art. Those skilled in the art will further recognize that modifications and variations to the features and / or steps specifically shown, referenced, and discussed herein may be made by reference thereto in the various embodiments and use of the disclosed technology without departing from the spirit and scope thereof. Variations include, but are not limited to, the substitution of equivalent means, steps, features, or materials to those shown, referenced, or discussed, as well as the functional, operational, or positional inversion of various parts, features, or steps, etc.

[0064] Furthermore, it will be understood that the various and presently preferred embodiments of the technology may include various combinations or configurations of the disclosed steps, features, or elements, or their equivalents, including combinations of those features, configurations, or steps not explicitly shown in the figures or described in the detailed description. [Brief description of the drawings]

[0065] A full and enabling description of the present disclosed subject matter, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in this specification, which makes reference to the accompanying drawings. [Figure 1] 1 is a schematic diagram of an exemplary presently devised test arrangement for testing either prior art devices or devices constructed and / or implemented in accordance with the presently disclosed techniques. [Figure 2A] FIG. 1 is a perspective view of a prior art multilayer ceramic capacitor (MLCC) device. [Figure 2B] FIG. 1 is a perspective view of a prior art multilayer ceramic capacitor (MLCC) device. [Figure 2C] FIG. 1 is a perspective view of a prior art multilayer ceramic capacitor (MLCC) device. [Figure 2D] FIG. 1 is a cross-sectional view of a prior art multi-layer ceramic capacitor (MLCC) device. [Diagram 3] 10 is a graph of comparative sound pressure tests resulting from the use of a test arrangement such as that represented by FIG. 1 above, performed on an existing MLCC device such as that represented by FIGS. 2A-2D above. [Figure 4A] FIG. 1 is a schematic diagram of an embodiment of mounting an MLCC device on a printed circuit board (PCB). [Figure 4B] FIG. 1 is a schematic diagram of an embodiment of mounting an MLCC device on a printed circuit board (PCB). [Figure 5A] FIG. 1 is a cross-sectional view of a first exemplary embodiment of the disclosed subject matter including a compliant termination technique for relatively reducing electromechanical noise. [Figure 5B]5B is a graph of a test resulting from the use of a test array as represented by FIG. 1 above, performed with an exemplary embodiment of the present disclosure as represented by FIG. 5A above. [Figure 6A] FIG. 1 is a perspective view of another exemplary embodiment of the disclosed subject matter including a molded packaging technique for relatively reducing electromechanical noise. [Figure 6B] FIG. 13 is a cross-sectional view of another exemplary embodiment of the disclosed subject matter including a molded packaging technique for relatively reducing electromechanical noise. [Figure 6C] 6A and 6B are graphs of tests resulting from the use of a test sequence as represented by FIG. 1 above, performed with the disclosed exemplary embodiment as represented by FIG. 6A and FIG. 6B above. [Figure 6D] 1A-1D are conceptual cross-sectional views of exemplary embodiments of capacitors and solder pads on a mounting substrate. [Figure 6E] 1A-1D are conceptual cross-sectional views of exemplary embodiments of capacitors and solder pads on a mounting substrate. [Figure 6F] 1A-1D are conceptual cross-sectional views of exemplary embodiments of capacitors and solder pads on a mounting substrate. [Figure 6G] FIG. 1 graphically illustrates the acoustic output of an exemplary embodiment as peak sound pressure level in dB. [Figure 7A] FIG. 2B shows a representative example of an 8-terminal MLCC device according to the prior art device design of FIGS. 2A to 2D above. [Figure 7B] FIG. 13 is a perspective view of another exemplary embodiment of the disclosed subject matter including a side terminal technique for relatively reducing electromechanical noise. [Figure 7C] 7B is a graph of a test resulting from the use of a test array as represented by FIG. 1 above, performed with an exemplary embodiment of the present disclosure as represented by FIG. 7B above. [Figure 8A] FIG. 1 is a perspective view of another example embodiment of the disclosed subject matter including a previously implemented MLCC transposer technology for relatively reducing electromechanical noise. [Figure 8B]A side elevation view of a component of another exemplary embodiment of the disclosed subject matter that includes pre-implemented MLCC transporter technology for relatively reducing electromechanical noise. [Figure 8C] A side elevation view of a board of another exemplary embodiment of the disclosed subject matter that includes pre-implemented MLCC transporter technology for relatively reducing electromechanical noise. [Figure 8D] A graph of tests obtained from the use of a test array as represented by FIG. 1 in an exemplary embodiment of the disclosed subject matter as represented by FIGS. 8A through 8C. [Figure 9] A graph of a comparative sound pressure test obtained from the use of a test array as represented by FIG. 1 in a disclosed MLCC device pre-implemented on a substrate as represented by FIGS. 8A through 8C.

[0066] The repeated use of reference signs throughout this specification and the attached drawings is intended to represent the same or similar features, elements, or steps of the disclosed subject matter.

DETAILED DESCRIPTION OF THE INVENTION

[0067] As discussed in the Summary of the Invention section, the disclosed subject matter generally relates to implemented capacitor devices and certain noise aspects of associated technologies and manufacturing and / or implementation methodologies. More particularly, the disclosed subject matter relates to improved designs for certain capacitor components and component assemblies associated with embodiments of surface mountable devices, and in particular, to providing low-noise capacitors and associated methodologies.

[0068] ​Selected combinations of aspects of the disclosed technology correspond to multiple different embodiments of the disclosed subject matter. It should be noted that each of the exemplary embodiments presented and discussed herein should not imply limitations of the disclosed subject matter. Features or steps shown or described as part of one embodiment may be used in combination with aspects of another embodiment to yield yet another embodiment. In addition, certain features may be replaced with similar devices or features not expressly mentioned that perform the same or similar functions.

[0069] Reference will now be made in detail to an exemplary and currently preferred embodiment, and in that regard, Figure 1 shows a schematic diagram of an exemplary presently contemplated test arrangement 10 for testing either prior art devices or devices constructed and / or implemented in accordance with the presently disclosed techniques. Such capacitor devices 12 may be surface mounted or otherwise positioned relative to a substrate 14, such as a printed circuit board. In the contemplated arrangement, copper supports 16 are provided on each side of the board 14 and may be energized during testing as represented by the indicated leads, as will be understood by those skilled in the art from the illustration of Figure 1 above.

[0070] The precision microphone 18 may be mounted at a given distance 20 from the substrate 14. In an exemplary arrangement, a distance of 2 mm may be achieved for the substrate 14, which may comprise a 100×40×1.5 mm PCB. The surface mounted devices 12 to be tested may include a variety of case sizes, such as 0201 to 1206.

[0071] The device to be tested may, for example, be solder reflow bonded to a pad in the center of the board. The use of a copper bracket 16 facilitates repeatable positioning of the test board, with the microphone located on the opposite side of the board from where the device to be tested is mounted. A foam enclosure (not shown) may be provided around the entire arrangement to reduce stray noise. With such an arrangement, the noise floor may be approximately -6 dB in the frequency range of interest, from about 1 to 10 kHz.

[0072] In an exemplary arrangement, a Bruel & Kjaer 1 / 2" Microphone and Preamp was used in conjunction with a Bruel & Kjaer Photon+ Signal Analyzer. An HP33120A function generator was used in conjunction with a Krohn-Hite Model 7500 amplifier used to power the test items with a 1-5 kHz swept sine wave; 3.15VAC; 3.15VDC; 0.1 second sweep rate. Most of the high CV capacitors tested had a 6.3V rating, so the test waveform was set to operate between 25% and 75% of 6.3 volts (approximately 1.6 to 4.7V).

[0073] Although various setup arrangements may be implemented, one skilled in the art will recognize that such microphone shapes and placements provide an effective arrangement for capacitor electromechanical noise testing, as represented by the concentric semicircular oscillating waves shown in FIG. 1 emanating from both the tested device 12 and the plate 14.

[0074] As otherwise discussed herein, Figures 2A, 2B, 2C, and 2D above are illustrative of prior art stacked layers as shown by Figures 2 and 3 of commonly owned U.S. Patent No. 5,933,363. 1A-1C are various perspective and cross-sectional views of a multilayer ceramic capacitor (MLCC) device that may have, for example, Ni-Sn plating on thick film Cu terminations along with a body having multiple interdigitated or interlaced sets of opposite polarity electrode structures 22 and 24, as will be appreciated by those skilled in the art.

[0075] 3 is a graph of a comparative sound pressure test resulting from the use of a test arrangement as represented by FIG. 1 above, performed on an existing MLCC device as represented by FIG. 2A-2D above. It graphs sound pressure level (SPL) in dB versus applied frequency in Hz. The noise floor is that represented by an empty test chamber. As shown, a representative peak occurs in this test at 49.3 dB within the tested frequency range between 1 and 9 kHz. A corresponding figure of merit display is created by the area under the SPL curve, which in this case amounts to about 2.0 Pa·Hz. Essentially the same test arrangement is used in conjunction with exemplary embodiments of the presently disclosed subject matter, as otherwise discussed herein.

[0076] 4A and 4B are schematic diagrams of mounting aspects of an MLCC device on a printed circuit board (PCB) in accordance with the disclosed subject matter, which contribute to reducing electromechanical noise from such a combination. As depicted, a representative disclosed MLCC device 26 is received (mounted and / or supported) relative to a supporting substrate 28 (such as a PCB). FIG. 4A depicts a technical approach to provide damping aspects in such a combination between the device 26 and the substrate 28. FIG. 4B depicts a reduction in forces that may otherwise result in mechanical forces and resulting noise in the supporting substrate. As depicted generally by such an embodiment, there is a reduction in the support / connection footprint between the device 26 and the substrate 28, resulting in a specified arrangement of reduced vibrational force transmission between the two.

[0077] Figure 5A is a cross-sectional view of a first exemplary embodiment of the disclosed subject matter including a compliant termination technique for relatively reducing electromechanical noise. Figure 5B is a graph of tests obtained from using a test array as represented by Figure 1 above performed on the disclosed exemplary embodiment as represented by Figure 5A above, comparing such results with those of a device terminated with a prior art thick Cu film as represented by prior art Figure 2D above.

[0078] In contrast to the prior art thick film copper termination of FIG. 2D, the disclosed exemplary embodiment of FIG. 5A has an Ag-polymer on a relatively thin Cu layer (or "flash"). Such a more compliant polymer termination acts as a "cushion" to dampen vibration coupling between the capacitor device and the PCB. While Ag-polymer is shown as a specific example, those skilled in the art will appreciate from the full disclosure herein that conductive polymers or polymers more generally may be implemented without being limited to Ag-polymer.

[0079] As shown by FIG. 5B above, the test results for the disclosed embodiment of FIG. 5A above are represented by the data points on the right and compared to the data points on the left with the prior art device (FIG. 2D). A reduction of approximately 6 dB is achieved. Because the dB axis is logarithmic, the reduction represented is in orders of magnitude that cuts the transmitted sound (SPL or noise) in half. The prior art embodiment of the thick film copper termination (FIG. 2D) has a modulus of elasticity of approximately 120 GPa, whereas the exemplary embodiment of the disclosed subject matter of FIG. 5A has a modulus of elasticity of less than 5 GPa. The exemplary embodiment for such testing purposes used 0805 10 microfarad MLCC devices. Thus, the disclosed embodiment of the compliant termination is shown to have a significant noise reduction over the prior art embodiment.

[0080] Figures 6A and 6B are perspective and cross-sectional views, respectively, of another exemplary embodiment of the disclosed subject matter including a molded packaging technique for relatively reducing electromechanical noise, and Figure 6C is a graph of a test resulting from the use of a test arrangement as represented by Figure 1 above, performed on the disclosed exemplary embodiment as represented by Figures 6A and 6B above.

[0081] The subject molded package embodiment includes the use of a lead frame to isolate the capacitor strain from the PCB. The length of the wire paths as shown and the respective top and end attachment points provide such isolation. A polymer coating also helps to attenuate device noise. Additionally, the so-called A-case package implements as an LGA (land grid array) style package on 0805 solder pads.

[0082] 6C graphically illustrates test results between a standard 0805 MLCC device (of the style presented by prior art FIG. 2D above) versus a 0805 A-Case sample using the disclosed molded packaging technology for a 22 microfarad device. As shown, the disclosed technology provides a range of 12 to 28 dB reduction in peak SPL, thus representing a significant improvement over the prior art.

[0083] 6D-6F show conceptual cross-sectional views of three different exemplary embodiments of capacitors and solder pads on a mounting substrate. FIG. 6D shows a multilayer ceramic capacitor device on a corresponding mounting pad, i.e., 0402 MLC mounts on pads designed for 0402 devices, 0603 MLC mounts on 0603 pads, etc. FIG. 6 shows a given MLC capacitor inserted into a molded device, which is physically larger than the MLC itself, and therefore causes the molded device to mount on solder pads designed for the molded part of that case size. In the EIA industry standard, molded devices for R- and N-case sizes mount on 0805 solder pads, molded parts for A-case mount on 1206 solder pads, molded devices for B-case mount on 1210 pads, etc. Notably, such industry standard mounting allows for the formation of solder fillets at the edges of the molded devices, as conceptually shown in FIG. 6E. However, when molded devices are mounted to solder pads designed for a chip one case size smaller, as shown conceptually in Figure 6F, the solder fillets at the edges of the molded devices are substantially eliminated. In other words, R- and N-case size molded devices are mounted on 0603 pads, A-case devices are mounted on 0805 pads, B-case devices are mounted on 1206 pads, etc.

[0084] As shown graphically in FIG. 6G, a typical 0603 MLC with capacitance in the range of 22 to 22 μF mounted on a 0603 mounting pad, and an A-case molded device with an MLC insert of the same value molded on an industry standard 1206 mounting pad, and on a smaller 0805 pad with the solder-end fillet removed. It is possible to compare the acoustic output as peak sound pressure level in dB with a mounted A-case device. The acoustic output of the A-case molded device is reduced versus a bare MLC insert, and furthermore, the acoustic output of a molded device mounted on solder pads that remove the solder end fillets is reduced versus a molded device mounted with solder fillets.

[0085] As shown graphically in Figure 6G, a typical 0402 MLC with capacitance ranging from 0.1 to 10 μF mounted on a 0402 mounting pad, an R-case molded device containing an MLC insert of the same value molded on an industry standard 0805 mounting pad, and an R-case molded device mounted on a smaller 0603 pad that removes the solder end fillets. It is possible to compare the acoustic output as peak sound pressure level in dB for devices with R-case molded devices. The acoustic output of R-case molded devices is reduced versus bare MLC inserts, and furthermore, the acoustic output of molded devices mounted on solder pads that remove the solder edge fillets is reduced versus molded devices mounted with solder fillets. Table 1 gives some examples of industry standard molded devices and MLC, as well as non-standard Land Grid Array (LGA) mounting pad geometries that minimize solder edge fillets to reduce acoustic output.

[0086] [Table 1]

[0087] FIG. 7A is a representative example of an 8-terminal MLCC device according to the prior art device design of FIGS. 2A-2D above. FIG. 7B is a perspective view of another exemplary embodiment of the presently disclosed subject matter including a side terminal technique for relatively reducing electromechanical noise. FIG. 7C is a graph of testing resulting from the use of a test arrangement as represented by FIG. 1 above performed on the presently disclosed exemplary embodiment as represented by FIG. 7B above, comparing the results of such testing with testing on a prior art embodiment as shown by FIG. 7A above. The exemplary embodiment of the side terminal has a relatively reduced coupling footprint and utilizes the reduction functionality and theme as generally represented by FIG. 4B above. Also, a reduction of about 6 dB is shown by the comparative test results of FIG. 7C above.

[0088] 8A-8C are perspective, component side elevation, and board side elevation views, respectively, of another exemplary embodiment of the disclosed subject matter including a prior implemented MLCC transposer technology for relatively reducing electromechanical noise. FIG. 8D is a graph of tests resulting from the use of a test array as represented by FIG. 1 above, performed on the disclosed exemplary embodiment as represented by FIG. 8A-8C above, and compared to a prior art MLCC embodiment such as the design of FIG. 2D above. Also, 0805 size devices are used for some of the comparison data points, and in some cases (as shown) a 0603 size embodiment is utilized. The term "transposer" is used literally because the location of mounting pads for a given case size MLCC are transposed to pads for a smaller case size device. This results in a reduction in effective bonding area, a reduction in the distance between mounting pads, induction of LGA type solder fillets, and an increase in MLCC device standoff.

[0089] For example, FIG. 8B generally illustrates, from the component side, a 0603 footprint for a capacitor mounting pad 30 as used with a solder mask 32 for mounting on a representative substrate 34. However, FIG. 8C, shown from the board (or substrate) side, illustrates that a transposer mounting pad 36 results in a 0201 footprint (dotted area 38). Thus, the Electronic Industries Association (EIA) mounting size is displaced by such an embodiment. Note that the EIA case size codes as discussed herein are referenced in inches. Table 2 below reflects various reductions in effective bond area that may be achieved by such implementation of the presently disclosed subject matter. Additionally, FIG. 8D illustrates a prior art MLCC device. 8D also graphically illustrates a 60 to 90% reduction in Figure of Merit (FOM) data.

[0090] [Table 2]

[0091] 9 above is a graph of comparative sound pressure level testing resulting from the use of a test arrangement as represented by FIG. 1 above, performed on a presently disclosed MLCC device previously mounted on a substrate as represented by FIG. 8A-8C above. As shown, the peak SPL shown over the 1 to 9 KHz range is about 23.8 dB, which is much less than the 49.3 dB peak SPL shown in the graph of FIG. 3 above. Similarly, the figure of merit is reduced to a range determination of about 0.4 Pa·Hz, down from about 2.0 Pa·Hz obtained in connection with the FIG. 3 testing. A comparative testing summary compared to such FIG. 3 graph for four different exemplary embodiments of the presently disclosed subject matter is shown in Table 3 below.

[0092] [Table 3]

[0093] Table 4 below summarizes the relative effectiveness of the presently disclosed embodiments of electromechanical noise (peak SPL) reduction versus size control and cost factors. Such comparative aspects may tend to indicate the selection of one particular presently disclosed embodiment over another for a particular application or set of user needs / criteria.

[0094] [Table 4]

[0095] Although the presently disclosed subject matter has been described in detail with respect to specific embodiments thereof, it will be recognized that those skilled in the art, upon arriving at the above understanding, can readily adapt the presently disclosed techniques to obtain modifications, additions, variations, and / or equivalents to such embodiments. Accordingly, the scope of the present disclosure is intended to be illustrative rather than limiting, and the disclosure of the subject matter does not preclude the inclusion of such modifications, variations, and / or additions to the presently disclosed subject matter as would be readily apparent to those skilled in the art.

Claims

[Claim 1] A surface mountable, relatively low noise, multi-layer ceramic capacitor (MLCC) capacitor assembly comprising: a body having a plurality of conductive layers of a first polarity and a second polarity, respectively, interleaved with a plurality of ceramic layers to form respective pairs of opposing capacitor plates in a stacked arrangement; a first polarity termination and a second polarity termination, respectively, at opposite ends of the body and electrically connected to the first polarity conductive layer and the second polarity conductive layer, the terminations including a compliant layer for relatively damping vibrations between the capacitor assembly and a surface on which the capacitor assembly is mounted to relatively reduce electromechanical noise; A capacitor assembly comprising:

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