CarbonConX®


Xerox has developed CarbonConX® as an alternative to unreliable and expensive metal contacts. Originally created for use in passive devices for electrostatic discharge applications, CarbonConX® has proven to be a preferred technology for electrical switch components. Xerox CarbonConX® technology offers high functionality with low complexity. Useful in a variety of applications, CarbonConX® makes use of pultrusion to form bundles of carbon fibers into each contact, ensuring redundancy in the contact point.

Technology Description

The CarbonConX® technology uses low-pressure pultrusion to bundle thousands of carbon fibers into each contact, ensuring redundancy in the contact point. This process involves pulling the carbon fibers and a thermoplastic or thermosetting polymer through a shaping/curing die. The result is a high-strength, electrically conductive contact.

Using carbon fibers makes the CarbonConX® reliable, inert, and multifunctional. Carbon fibers are less susceptible to corrosion than metal contacts. Their nonreactive nature makes them ideal for use in harsh environments, including saltwater, nuclear power, space, or medical X-ray environments. Additionally, pultruded carbon fiber contacts can act as structural members, due to the high strength material characteristics of the polymer and carbon bundle. The high number of contacting fibers makes CarbonConX® attractive for applications where reliability is critical.

As produced, CarbonConX® surfaces are inherently contact rich, providing statistically regular, evenly distributed contact sites. The effective surface area of a CarbonConX® can be greater than the simple planar surface area, depending on the engagement length of the fibers. The primary characteristics of a CarbonConX® are:
  • High density of evenly distributed conduction sites
  • Robust character of the carbon fibers results in high immunity to the formation of non-conductive films and high contact integrity in contact degrading environments
CarbonConX® may be produced exhibiting conductivities in the metallic range with the application of metal coated fibers. By use of controlled carbonization techniques, the electrical conductivity of the carbon fibers can be precisely tuned. A wide range of conductivities can be achieved by the use of this process and designed directly into the CarbonConX® material. Integrating the resistor function into the contact structure further simplifies component design, reduce part count, lowers cost and improves reliability. Non plated CarbonConX® can be applied with advantage over metallic contacts especially in low energy circuitry. Typically, applied voltages of 100VDC or less and current levels on the order of 100 ma/mm2 are practical. CarbonConX® contact resistances of a few hundred milliohms to a few hundred ohms are determined by contact geometry, fiber characteristics and normal force.

Key Specifications at a glance

Mechanical properties: Supplemental information for T-300/M826/dia 1.6
Carbon fiber
Tensile strength (min) 3.1GPa(440 kpsi)
Tensile modulus(min) 214 GPa(31x106psi)
Percent Elongation(min) 1.2
Tensile strength(typical) 512 kpsi
Tensile modulus(typical) 33x106psi
Percent Elongation(typical) 1.5
Electrical resistivity 1500 microohms-cm
Polymer Modar 826 – modified acrylic resin
Flexural strength 21,000 psi
Flexural modulus 0.54 x 106psi
Tensile strength 12,750psi
Tensile modulus 0.60 x 106psi
Percent Elongation 3.3

Benefits

CarbonConX® has the following advantages over metal contacts:

Reliable - CarbonConX® provides more contact area (i.e., thousands of conducting fibers per contact), resist films formed on metal contacts, and have lower failure rates.

Rugged - CarbonConX® resists corrosion and contamination, even in harsh environments.

Multifunctional - Using pultrusion to bundle the carbon fibers allows the CarbonConX® to conduct electricity and provide structural support.

Inert - Carbon fibers are nonfilming.

Versatile - CarbonConX® can be manufactured in various design shapes and configurations.

Low cost - CarbonConX® have commodity pricing and use simple, efficient manufacturing processes.

Proven - CarbonConX® have been in practice for many years in commercially available products. Manufacturing capability already exists to support future expansion of the technology.

Applications

  • Aerospace
  • Consumer electronics
  • DC motors
  • Diagnostic X-ray equipment
  • Electrical switches
  • Electrostatic discharge devices
  • Interconnects
  • Medical X-ray equipment
  • Moving rotational contacts
  • Nuclear environment sensors
  • Outdoor lighting contacts
  • PWB interconnects
  • Robotics
  • Sensor components
  • Underwater electrical devices

Intellectual Property Summary

The CarbonConX® technology encompasses a patent portfolio of over 30 patents, published applications and know-how. Issued core patents relating to CarbonConX® include U.S. 6,214,921 (Electrical component) and U.S. 7,220,131 (Electromechanical device having a plurality of bundles of fibers for interconnecting two planar surfaces); U.S. 8,018,059 (Electrical interconnect with an electrical pathway including at least a first member overlain by a second member at a contact point).

Additional CarbonConX® technology patents and published applications are listed below.

U.S. 8518506 PRECISION RESISTIVE ELEMENTS AND RELATED MANUFACTURING PROCESS
U.S. 7927749 Microbial fuel cell and method
U.S. 7807303 Microbial fuel cell and method
U.S. 7847191 Electrical component, manufacturing system and method
U.S. 7789734 Multi-orifice fluid jet to enable efficient, high precision micromachining
U.S. 7307112 Electrical component with fillers having semi-resistive properties and composite systems comprising the same
U.S. 7266322 Multi-functional electro-mechanical interconnect, sensor, and mounting and method of mounting and biasing of a rotatable member
U.S. 7220131 Electromechanical device having a plurality of bundles of fibers for interconnecting two planar surfaces
U.S. 7105594 Conductive carbon filled polyvinyl butyral adhesive
U.S. 7067027 Method of making an electro-mechanical roll
U.S. 7052763 Multi-element connector
U.S. 6584296 Electro-mechanical roll with core and segments
U.S. 6289187 Carbon fiber commutator brush for a toner developing device and method for making
U.S. 6265046 Electrical component having fibers oriented in at least two directions
U.S. 6246012 Electroplated conductive carbon fibers with adhesive
U.S. 6214921 Electrical component
U.S. 5887225 Solid carbon fiber electrical rod developer bias contacting method

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