Patent Application
20130025907
The subject matter herein relates generally to carbon-based substrate (CBS) conductors, cables and other electrical components using CBS conductors and methods of manufacturing CBS conductors, cable or other electrical components using CBS conductors.
CBSs may include carbon nanotubes (CNTs), graphene or other carbon-based networks as the substrate. CBSs have use in a wide range of applications. Due to the electrical conductivity exhibited by CBSs, CBSs have application in electrical systems, such as use as electrical conductors of cables, wires or other conductors, as electromagnetic interference (EMI) shielding for cables or other types of electronic components, and other applications. Due to the relative light weight of CBSs, as compared to traditional metal components, CBSs have application in aeronautical application where weight is a significant design factor.
CBSs for use as electrical conductors are not without disadvantages. For instance, for some applications, such as for EMI shielding, the electrical conductivity of the CBS network is inadequate. Additionally, termination of the CBS to another electrical component, such as a contact, a circuit board or another electrical component has proven difficult. For example, soldering of the CBS to a contact is difficult and the CBS tends to exhibit high contact resistance at the interface. Crimping of the CBS to a contact or connector leads to poor termination and thus poor electrical results.
A need remains for a CBS network that exhibits good electrical characteristics. A need remains for a CBS network that can be terminated to make contact to a larger circuit.
In one embodiment, a cable is provided having a jacket surrounding a core. A carbon-based substrate (CBS) conductor is provided in the core. The CBS conductor includes a CBS network that is metalized with a metalized layer. For example, the CBS network may be plated with metal plating. The CBS network may be a CNT network, a graphene network or another carbon-based network.
Optionally, the metalized layer may be at least one of silver metalized layer, copper metalized layer, gold metalized layer, nickel metalized layer, and/or tin metalized layer. The metalized layer may be annealed after the metallization process.
Optionally, the CBS network may include a plurality of CNT fibers forming a framework. The CBS network may be one of a yarn, a sheet, or a tape. The CBS network may be electrically conductive. The CBS based network may be modified to create a passive dielectric or insulating component. The CBS based network may be modified to make other compounded/composite surfaces. Optionally, the metalized layer may be applied to a portion of the CBS network forming an end of the CBS conductor. Alternatively, substantially the entire CBS network may be metalized with the metalized layer. Optionally, the CBS conductor may be a signal carrying conductor of the cable. A plurality of the CBS conductors may be twisted along a length of the cable to form a central conductor of the cable. The CBS conductor may surround the core and provides EMI shielding for the core.
Optionally, the cable may further include an insulator and a second CBS conductor in the core. The insulator may surround the CBS conductor, the second CBS conductor may surround the insulator, and the jacket may surround the second CBS conductor. The second CBS conductor may provide EMI shielding for the other CBS conductor which is configured to convey electrical signals between a first end and a second end of the cable.
Optionally, the cable may further include a contact terminated to the CBS conductor at the first end of the cable. The metalized layer may be provided at the interface between the CBS conductor and the contact to enhance the electrical interface between the CBS conductor and the contact.
In another embodiment, a method for manufacturing a carbon-based substrate (CBS) conductor is provided. The method includes providing a CBS network of CBS fibers or sheets forming a framework. The method includes metalizing at least a portion of the CBS network with a metalized layer. The metalizing may include plating. The metalizing may include immersing at least a portion of the CBS network in a metallic bath. The CBS network may be formed by extracting CBS fibers from a CBS array to form the framework having a shape of one of a yarn, a tape or a sheet. The metalized CBS network may be subjected to post-processing. The metalized CBS network may be used to form a cable or as part of another electrical system.
The EMI shield 106 and the center conductor 110 are electrically conductive. The cable 100 defines a coaxial cable having the center conductor 110 and an outer conductor defined by the EMI shield 106 extending along a common axis along the length of the cable 100. The cable 100 may be another type of cable, such as a twin-axial cable, a quad-axial cable, an unshielded cable, and the like. The center conductor 110 is configured to convey electrical signals between a first end 112 (shown in
In an exemplary embodiment, the center conductor 110 and the EMI shield 106 are manufactured from a carbon-based substrate (CBS), such as carbon nanotubes (CNTs), graphene, a graphite oxide structure, and the like. Alternatively, the center conductor 110 and the EMI shield 106 are manufactured from another nano-substrate, such as a ceramic nanowire, such as a boron nitride substrate. The CBS based network may be modified to create other types of electronic components such as a passive dielectric or insulating component. The CBS based network may be modified to make other compounded/composite surfaces.
The center conductor 110 defines a CBS conductor, and may be referred to hereinafter as a CBS conductor 110. Optionally, the center conductor 110 may include one or more strands of CBS conductors that are twisted together during a cable forming process. The EMI shield 106 defines a CBS conductor, and may be referred to hereinafter as a CBS conductor 106. In an alternative embodiment, only the center conductor 110 is manufactured from a CBS. In another alternative embodiment, only the EMI shield 106 is manufactured from a CBS.
In an exemplary embodiment, each CBS conductor 106, 110 is manufactured from a CBS network that is at least partially metalized with a metalized layer. The metalized layer may be a single layer or multiple layers. The metalized layer may be a coating surrounding an outer surface of the CBS network or may at least partially permeate through, or be infused into, the CBS network. The CBS network may be a CNT network, a graphene network or another carbon-based network. Optionally, select portions of the CBS conductors 106, 110 may be metalized with the metalized layer. Alternatively, substantially the entire CBS conductors 106, 110 may be metalized with the metalized layer. In an exemplary embodiment, the metalized layer is a silver metalized layer, such as a silver plating. In other embodiments, the metalized layer may be other types of metalized layers, such as a copper metalized layer, a gold metalized layer, a nickel metalized layer, a tin metalized layer and the like. The type of metal used for metalizing is selected to enhance certain characteristics of the CBS network, such as the electrical characteristics, the mechanical characteristics, the solderability characteristics and the like. Optionally, different parts of the CBS conductors 106, 110 may be metalized with different types of metalized layers. Optionally, different portions of the CBS conductors 106, 110 may be metalized with more than one metalized layers or materials, making a multi-layered metalized substrate. For example, the entire CBS network may be metalized with one metalized layer, such as a silver plating, to make the CBS conductor more conductive and ends of the CBS conductors may be metalized with another metalized layer, such as a tin plating, to make the CBS conductor more solderable.
In an exemplary embodiment, the metalized layer is electroplated. The metalized layer may be applied by other processes in alternative embodiments. Optionally, portions or all of the CBS network may be subjected to surface functionalization to introduce chemical functional groups to at least a portion of the surface of the CBS network. For example, functionalization of the ends of CBS fibers, bundles, yarns, tapes or sheets may be performed. The functionalization process may include corona discharge and/or plasma treatment, such as plasma treatments at energy levels sufficient to break all bond types (e.g., VanDerWaal-London through covalent). The functionalization process may include wet chemistry. The functionalization process may include in situ functionalization during chemical vapor deposition (CVD) treatment by use of chemical gas mixtures. The metallization may include, either with or without prior functionalization, physical vapor deposition, metallo-organic CVD in-situ, dip coating in conductive ink/paste, or other processes to metalize the CBS network.
The metalized layer may be further processed to enhance the characteristics of the conductor. For example, the metalized layer may be annealed after being applied. Other processes may be utilized in alternative embodiments.
In an exemplary embodiment, each strand 132 is a separate CBS conductor manufactured from a CBS network 134 that is metalized with a metalized layer 136. The CBS network 134 may be selectively metalized to different portions of the CBS conductor. In the illustrated embodiment, the metalized layer 136 is provided around the outer perimeter of the CBS network 134. In alternative embodiments, the metalized layer 136 may extend or permeate entirely through the CBS network 134 such that the CBS network 134 is metalized entirely therethrough.
The first and second electrical components 116, 118 are represented schematically in
In an exemplary embodiment, the CBS network of the CBS conductor is conductive and is configured to convey electrical signals between the first and second electrical components 116, 118. The metalized layer may enhance the electrical properties of the center conductor 110 and/or EMI shield 106. For example, the conductivity of the CBS-based center conductor 110 and/or EMI shield 106 may be increased by selecting a metal material having a high conductivity, such as silver, copper, gold, nickel, tin and the like. The CBS-based center conductor 110 and/or EMI shield 106 may be easier to solder with the addition of the metalized layer either at the ends 112, 114 and/or along the entire length of the cable 100 by lowering the contact resistance of the center conductor 110 and/or EMI shield 106.
In the illustrated embodiment, the EMI shield 106 is metalized along the entire length of the CBS network to increase the conductivity of the CBS network to provide shielding along the entire length. In the illustrated embodiment, the center conductor 110 is metalized only at the ends 112, 114, such as in the exposed areas 126, 128 of the center conductor 110, which are the areas that are configured to be soldered to the electrical components 116, 118. The metalizing at the areas 126, 128 reduces the contact resistance at the interface between the CBS network and the electrical components 116, 118. The metalizing at the areas 126, 128 may increase the solderability at the interface between the CBS network and the electrical components 116, 118. By selectively metalizing only in the areas 126, 128, the overall cost of the cable 100 may be reduced. It is realized that the entire center conductor 110 or other portions of the center conductor 110 other than the areas 126, 128 may also be metalized. In an exemplary embodiment, the entire center conductor 110 is metalized, such as with silver, to increase the electrical conductivity of the center conductor 110 and the ends 112, 114 are metalized, such as with tin, to increase the solderability of the center conductor 110.
In an exemplary embodiment, the framework 152 may be pulled from a CBS array or CBS source, such as by using a spinning technique. The framework 152 may be formed into a yarn or wire. The framework 152 may be a braided yarn or a mesh. Alternatively, the framework 152 may be formed into a tape. Alternatively, the framework 152 may be formed into a sheet. The wire, tape or sheet may have any length depending on the particular application. A wire is defined as having a width that is less than approximately two times a thickness of the framework 152. A tape is defined as having a width that is greater than approximately two times the thickness of the framework 152 and having a width that is less than approximately ten times the thickness of the framework 152. A sheet is defined as a framework having a width that is greater than approximately ten times the thickness of the framework 152. The framework 152 may have different shapes depending on the particular application.
The wires or yarns may be used, for example, to define the strands of the center conductor 110 (shown in
During manufacture, CBS fibers are pulled or otherwise extracted from the CBS array 200 to make a framework or CBS network. The CBS network may be taken in the form of a wire or yarn, a tape, a sheet and the like. The CBS network is then metalized. In the illustrated embodiment, the CBS network is plated, however other processes may be used in alternative embodiments to metalize the CBS network. The CBS network is directed to the metallic bath 202 where the CBS network is plated with metal plating. Optionally, the CBS network may be electroplated. A power supply 210 may be provided with one or more stainless steel bars 212, or other metallic bars, electrically connected to the power supply 210. The stainless steel bars 212 may be connected to the positive terminal(s) of the power supply 210 to define an anode(s). The CBS network may be electrically connected to the power supply 210, such as to the negative terminal(s), to define a cathode. The metal plating is applied to the CBS network when power is supplied to the metallic bath 202 via the bars 212 and/or the CBS network. Optionally, portions of the CBS network may be selectively plated. Optionally, more than one metallic baths may be provided.
The metalized CBS network is directed to the post-processing module 204. At the post-processing module 204 the CBS conductor may be subjected to heating, cooling, shrinking, twisting, doping, densification, pressing, forming or other processes to affect the interaction between the metalized layer and the CBS network and/or to define a shape of the CBS conductor.
The CBS conductor is directed to the cable forming module 206 to form a cable, such as the cable 100 (shown in
In alternative embodiments, rather than using the CBS conductors to form cables, the CBS conductors may be used to form other electrical components, such as an electrical connector, a processor, a circuit board, or another electrical component. The CBS conductor may be used as part of a signal conductor or alternatively may be part of an EMI shield or another part of an electrical component.
The method includes incorporating 256 the metalized CBS network into a cable. For example, the CBS network may be presented to a cable forming machine that pulls the CBS network into a cable form within a jacket. The method includes electrically connecting 258 the CBS network to an electrical source to form a CBS conductor. For example, the CBS network may be soldered to a contact, a circuit board or another electrical component at one or both ends of the CBS network, and data signals may be conveyed along the CBS network between the opposite ends of the cable.
The metalized CBS network may be used in other types of electrical systems other than a cable, such as an electrical connector, a microprocessor, or another type of electrical component. Any application suitable for use with CBSs may utilize the metalized CBSs. The metalized layer on the CBS network enhances the characteristics of the CBS network, such as electrically, mechanically, for solderability and the like.
In the illustrated embodiment, the measured sheet resistance of the un-plated CBS conductor 278 is approximately 0.4. The measured sheet resistance of the silver metalized CBS conductor 280 is approximately 0.01. The measured sheet resistance of the copper metalized CBS conductor 282 is approximately 0.09. The measured sheet resistance of the gold metalized CBS conductor 284 is approximately 0.1. The measured sheet resistance of the annealed silver metalized CBS conductor 290 is approximately 0.004. The measured sheet resistance of the annealed copper metalized CBS conductor 292 is approximately 0.05. The measured sheet resistance of the annealed gold metalized CBS conductor 294 is approximately 0.1. All of the metalized CBS conductors 280-294 have lower sheet resistance than the un-plated CBS conductor 278, and thus have improved electrical characteristics as compared to the un-plated CBS conductor 278.
It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Dimensions, types of materials, orientations of the various components, and the number and positions of the various components described herein are intended to define parameters of certain embodiments, and are by no means limiting and are merely exemplary embodiments. Many other embodiments and modifications within the spirit and scope of the claims will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Further, the limitations of the following claims are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. §112, sixth paragraph, unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure.
