The present subject matter generally concerns a high current chip-type feed-through device that may be utilized for surge protection in a variety of electronic applications. More particularly, the disclosed device is a multi-layer, transient suppressing, feed-through device that is characterized by high current carrying and varistor-like surge suppression capabilities.
A varistor, short for a “voltage-variable resistor,” is a device that has voltage-dependent nonlinear resistance characteristics. Most varistors are composed of a semiconductive material whose resistance is dependent on the voltage applied to the device. A varistor is typically connected in parallel to some electronic device or circuit element in order to protect that device or element from excess voltages. When the electronic device or circuit element is subjected to an increased voltage level, the resistance of the varistor drastically decreases. Thus, in the case of transient voltages, a varistor essentially short circuits the device it is connected to such that potential component damage due to over voltage may be avoided.
Varistors can help provide protection against many types of over voltages, including those caused by lightning, inductive switching, nuclear electromagnetic pulses (NEMP), electrostatic discharge (ESD), or electromagnetic interference (EMI). The performance characteristics of a varistor make it appealing as a protective device in many applications. Such applications include data systems, power supplies, switching equipment, telecommunications systems including RF antennas and RF amplifiers, consumer electronics, automotive systems, and industrial equipment such as control systems, alarm systems, proximity switches, transformers and motors. Varistors may often be particularly beneficial for protecting semiconductor components that are highly sensitive to transient voltages, including silicon diodes and transistors.
Two general types of varistor structures are known in the art, and these correspond to so-called “pressed-pill” type varistors and multi-layer chip-type varistors. The pressed-pill type varistors utilize single layer technology to create generally larger, radial or axial leaded components. These pill varistors typically provide a generally high amount of power protection. An example of a varistor with this pressed-pill type of structure is disclosed in U.S. Pat. No. 5,594,406 (Koyama et al.)
Multi-layer chip varistors are the result of relatively newer technological endeavors, and are typically designed for easy mounting to a substrate. They often are composed of a semiconductive body with internal electrode layers embedded within the device. Peripheral terminations may also be utilized for electrical connection to the internal electrode layers and convenient attachment of the varistor chip to a substrate. Many of such small chip-type devices adapt better than the pill-type devices to the high packaging density of modern integrated circuits and other environments. Examples of protective semiconductor devices characterized by such internal electrodes and end terminations can be found in U.S. Pat. No. 5,976,420 (Nakamura et al.), U.S. Pat. No. 5,119,062 (Nakamura et al.), and U.S. Pat. No. 4,729,058 (Gupta et al.).
Another example of a known multi-layer varistor device is the TransFeed brand transient voltage suppressor, such as that offered for sale by AVX Corporation. This transient voltage suppressor has significant voltage and energy handling capabilities and also EMI/RFI attenuation. Its chip-type design corresponds to a plurality of internal electrode layers embedded in a body of zinc oxide and configured to provide both signal feedthru and transient voltage suppression.
Other signal feedthru and transient voltage suppression arrangements are exemplified by feedthru capacitor devices such as can be found in U.S. Pat. No. 4,935,842 (Carlson et al.) and U.S. Pat. No. 5,531,003 (Seifried et al.).
While various aspects and alternative features are known in the field of feedthru capacitor technology, no one design has emerged that generally integrates all of the ideal features and performance characteristics as discussed herein.
Exemplary background references in addition to those already cited in the specification include the publications by AVX Corporation entitled “Feedthru 0805/1206 Capacitors, W3F/W3F Series” and “Feedthru 0805/1206 Capacitors, W3F/W3F/W3F4 Series” available on AVX Corporations website at the URL address: www.avxcorp.com. The disclosures of all the foregoing United States patents are hereby fully incorporated into this application by reference thereto.
The present subject matter recognizes and addresses various of the foregoing aspects of feedthru capacitor technology. Thus, broadly speaking, an object of the presently disclosed technology is the provision of improved feedthru capacitor configurations and corresponding performance. More particularly, an object of the disclosed technology is to offer an improved configuration for a multi-layer feedthru chip-type capacitor device.
Another object of some embodiments of the present subject matter is to provide a multi-layer feedthru capacitor that offers effective surge protection and dependable performance for sensing and limiting transient energy pulses in a variety of electronic applications.
Yet another object of some embodiments of the presently disclosed technology is to provide a multi-layer feedthru capacitor that offers a significant increase in current carrying capabilities over that of known multi-layer feedthru capacitor structures.
A still further object of some embodiments of the present subject matter is to provide a multi-layer feedthru capacitor that offers a significant increase in current carrying capabilities while at the same time providing such increased capabilities in a device utilizing the same form factor, or overall component size, as previous, less robust devices.
Another object of some embodiments of the present technology is to provide a multi-layer feedthru device that provides dual frequency filtering by adjusting selected electrically conductive elements to predetermined lengths.
Yet another object of some embodiments of the presently disclosed technology is to provide various process steps and methodology associated with the formation of exemplary multi-layer feedthru capacitor configurations and embodiments as discussed herein.
Additional objects and advantages of the present subject matter are set forth in, or will be apparent to those of ordinary skill in the art from, the detailed description herein. Also, it should be further appreciated by those of ordinary skill in the art that modifications and variations to the specifically illustrated, referenced, and discussed features and steps hereof may be practiced in various embodiments and uses of this subject matter without departing from the spirit and scope thereof, by virtue of present reference thereto. Such variations may include, but are not limited to, substitution of equivalent means and features, materials, or steps for those shown, referenced, or discussed, and the functional, operational, or positional reversal of various parts, features, steps, or the like.
Still further, it is to be understood that different embodiments, as well as different presently preferred embodiments, of this subject matter may include various combinations or configurations of presently disclosed features, steps, or elements, or their equivalents (including combinations of features or steps or configurations thereof not expressly shown in the figures or stated in the detailed description).
A first exemplary embodiment of the present subject matter corresponds to a multi-layer feedthru device including a body having a width dimension generally shorter than a length dimension thereof, and having multiple alternating layers of conductive and semiconductive material. Selected of the layers of conductive material correspond to main signal carrying conductors that extend along the generally shorter width of the device body, while other layers of conductive material correspond to transient grounding electrical conductors that extend along the length of the device body in a generally perpendicular fashion to the main signal carrying conductors. The main signal carrying conductors have a generally wide current path such that the resulting internal equivalent series resistance of the feedthru device is relatively decreased while the current handling capability of the feedthru device is relatively increased.
In some more particular exemplary embodiments of the above multi-layer feedthru device, each transient grounding electrical conductor comprises paired portions having respective first and second predetermined lengths. The first and second predetermined lengths may be substantially equal in some embodiments or may be substantially not equal in other embodiments to provide dual frequency filtering at two different respective predetermined frequencies. The length of the multi-layer feedthru device may be about twice as long as the generally shorter width of the device, and relatively wider current paths of the main signal carrying conductors may have dimensions that are greater than the generally shorter width of the device. The multi-layer feedthru device may also include metallic elements, at least one of which is attached to and electrically connecting selected of the main signal carrying conductors, and at least one of which is attached to and electrically connecting selected of the transient grounding electrical conductors.
Another exemplary embodiment of the present subject matter corresponds to a multi-layer feedthru device including a body of semiconductive material, a plurality of generally planar first conductive layers disposed within the body of semiconductive material and configured for propagation of electrical signals therethrough, and a plurality of generally planar second conductive layers also disposed within the body of semiconductive material and configured for connection thereof to an electrical ground. The body of semiconductive material has a first pair of opposing sides spaced from one another by a first dimension and a second pair of opposing sides spaced from one another by a second dimension. Each of the first conductive layers extends along the first dimension between the first pair of opposing sides, and each first conductive layer is also characterized by a third dimension. Each second conductive layer extends along the second dimension between the second pair of opposing sides. In the above exemplary configuration, the third dimension is longer than the first dimension, and the second dimension is longer than the third dimension.
In more particular embodiments of the above-referenced feedthru device, the second dimension may be about twice as long as the first dimension and the third dimension may have a value equal to about seventy-five percent of the second dimension. The body of semiconductive material may comprise a metal oxide such as zinc oxide. The device may have an increased current rating, such as one on the order of between about five and about ten Amperes. Electrical terminations may also be provided on respective sides of the device for connecting first conductive layers together and separately connecting second conductive layers together.
Yet another exemplary embodiment of the present subject matter corresponds to a multi-layer feedthru device including a plurality of semiconductive layers, a plurality of conductive ground layers and a plurality of conductive signal layers alternately interleaved among the plurality of semiconductive layers so as to form a stacked assembly. The stacked assembly has respective topmost and bottommost layers (which correspond to semiconductive layers in some embodiments), a pair of first opposing side surfaces separated from one another by a first distance, and a pair of second opposing side surfaces separated from one another by a second distance. The second distance is greater than the first distance. Each conductive signal layer extends to and is exposed along at least one side surface of the pair of first opposing side surfaces, while each conductive ground layer extends to and is exposed along at least one side surface of the pair of second opposing side surfaces.
In more particular exemplary embodiments of the above multi-layer feedthru device, the second distance may be about twice as long as the first distance. In other embodiments, the portion of each conductive signal layer exposed along at least one side surface of the pair of first opposing side surfaces is characterized by a third distance that is generally greater than the first distance, and in some embodiments has a value equal to about seventy-five percent of the second distance. The plurality of semiconductive layers may comprise zinc oxide in some embodiments, and the device may have a current rating of between about five and about ten Amperes in some embodiments. An exemplary multi-layer feedthru device may also include at least one first electrical termination provided on each side surface of the pair of first opposing side surfaces and connected to each of the plurality of conductive signal layers, as well as at least one second electrical termination provided on each side surface of the pair of second opposing side surfaces and connected to each of the plurality of conductive ground layers.
In still further more particular exemplary embodiments, each conductive ground layer includes respective first and second conductive portions, wherein each first conductive portion of each conductive ground layer extends to and is exposed along a selected one of the pair of second opposing side surfaces and is characterized by a distance L1, and wherein each second conductive portion of each conductive ground layer extends to and is exposed along the other of the pair of second opposing side surfaces and is characterized by a distance L2. Distances L1 and L2 may be substantially equal in some embodiments or may be different values so as to effect signal filtering at two different predetermined frequencies in other embodiments. In such embodiments, at least one first electrical termination may be provided on each side surface of the pair of first opposing side surfaces and connected to each of the plurality of conductive signal layers, while at least one second electrical termination is provided on a selected one of the pair of second opposing side surfaces and connected to each of the first conductive portions of each conductive ground layer and at least one additional second electrical termination is provided on the other one of the pair of opposing second side surfaces and connected to each of the second conductive portions of each conductive ground layer.
A still further exemplary embodiment of the present subject matter corresponds to a surface-mounted feedthru device including a printed circuit board, a feedthru device, and first, second, third and fourth electrical connections. The printed circuit board has at least one signal line connection thereon and at least one ground plane connection thereon. The feedthru device more particularly includes a body of semiconductive material, a plurality of generally planar conductive signal layers disposed within the body of semiconductive material, and a plurality of generally planar conductive ground layers disposed within the body of semiconductive material. The body of semiconductive material has a first pair of opposing sides spaced from one another by a first dimension and a second pair of opposing sides spaced from one another by a second dimension, wherein the second dimension is greater than the first dimension. Each generally planar conductive signal layer extends to and is exposed along at least one of the first pair of opposing sides, while each generally planar conductive ground layer extends to and is exposed along at least one of the second pair of opposing sides. The first and second electrical connections connect the generally planar conductive signal layers to the at least one signal line connection on the printed circuit board, while the third and fourth electrical connections connect the generally planar conductive ground layers to the at least one ground plane connection on the printed circuit board.
In accordance with more particular exemplary embodiments of the above exemplary surface-mounted feedthru device, the first, second, third and fourth electrical connections may comprise solder connections and/or terminations provided on selected sides of the body of semiconductive material. The second dimension of the body of the feedthru device may be about twice as long as the first dimension. The portion of each generally planar conductive signal layer exposed along at least one of the first pair of opposing sides may be characterized by a third dimension greater than the first dimension. Each generally planar conductive ground layer may include respective first and second conductive portions, wherein each first conductive portion of each generally planar conductive ground layer extends to and is exposed along a selected one of the second pair of opposing sides and is characterized by a distance L1, and wherein each second conductive portion of each generally planar conductive ground layer extends to and is exposed along the other of the second pair of opposing sides and is characterized by a distance L2. Distances L1 and L2 may be substantially equal in some embodiments or may be different values so as to effect signal filtering at two different predetermined frequencies in other embodiments.
Such exemplary embodiments and others in accordance with the disclosed subject matter may preferably be created using various aspects of thin-film technology. For example, certain elements of the subject multi-layer feedthru capacitor may be applied in accordance with plating or etching methods or aspects of photolithography as should be well known by one of ordinary skill in the art of thin film components and related techniques.
Additional embodiments of the subject technology, not necessarily expressed in this summarized section, may include and incorporate various combinations of aspects of features, parts, or steps referenced in the summarized objectives above, and/or features, parts, or steps as otherwise discussed in this application.
The present subject matter equally concerns various exemplary corresponding methodologies for practice and manufacture of all of the herein referenced multi-layer feedthru capacitor configurations and related technology.
Those of ordinary skill in the art will better appreciate the features and aspects of such embodiments, and others, upon review of the remainder of the specification.
A full and enabling description of the present subject matter, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:
Repeat use of reference characters throughout the present specification and appended drawings is intended to represent same or analogous features or elements of the present subject matter.
As referenced in the Brief Summary of the Invention section, supra, the present subject matter is directed towards improved multi-layer feedthru capacitor configurations and performance characteristics thereof.
More particularly, one example of the disclosed multi-layer feedthru capacitor offers a significantly higher current carrying capacity than previously available and does so using substantially the same form factor as previously employed with less robust, but generally similar, devices.
A known arrangement of a multi-layer feedthru capacitor will be discussed with reference to
Referring now to the drawings,
Further with respect to the previously known device depicted in
A first exemplary embodiment of the present technology will now be described with reference to
A significant difference between the present technology and that previously known resides in the substantial reversal of geometry between the present and previous technologies. As is evident from a comparison of
With further reference to the exemplary feedthru device embodiment 20a, in an exemplary 1206 form factor, the second dimension 25 is about twice as long as the first dimension 35. As such, the equivalent series resistance is reduced by 50% due to reducing the current path through the chip from 120 mils to 60 mils. Furthermore, each conductive signal layer 32, 34, 36 and 38 has a generally wide current path characterized by a third dimension 45. The equivalent series resistance is reduced again due to the fact that this current path has increased in width from 45 mils to 90 mils (i.e., the third dimension 45 is greater than the first dimension 35 and about seventy-five percent (75%) of the second dimension 25). The combination of these reductions provides an overall 75% reduction in internal resistance and a consequent increase in the current handling capability of the device. As previously noted, prior similar devices were rated at 300 mA while the present technology enables current ratings of 5 to 10 amperes or more in a device using the same form factor as the previously known technology. An additional advantage is obtained by this construction in that the much wider electrode tab resulting from the much wider electrically conductive electrode element provides a better termination to electrode connection when securing the devices to circuit boards and generally within other electronic devices.
A second exemplary embodiment of the present subject matter is now presented with respect to
The main difference between the first exemplary feedthru device embodiment 20a (as depicted in
While the present subject matter has been described in detail with respect to specific embodiments thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing may readily produce alterations to, variations of, and equivalents to such embodiments. Accordingly, the scope of the present disclosure is by way of example rather than by way of limitation, and the subject disclosure does not preclude inclusion of such modifications, variations and/or additions to the present subject matter as would be readily apparent to one of ordinary skill in the art.
This application claims the benefit of U.S. Provisional Application No. 60/536,066, entitled “HIGH CURRENT FEEDTHRU DEVICE”, filed Jan. 13, 2004, and naming inventors Wilson Hayworth and Ronald S. Demcko, which provisional is incorporated herein by reference for all purposes.
Number | Date | Country | |
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60536066 | Jan 2004 | US |