ASI has recently developed the ability to produce high-quality uniform CNF-reinforced, polymer films. ASI’s thin film materials are well-suited for use as pre-pregging sheets or as fully-cured surface coating materials for EMI shielding.
ASI was awarded a Navy Phase II Small Business Innovative Research (SBIR) program to refine the production methodology for these products and produce pilot scale sized thin films. This program will build on the success from a Navy Phase I SBIR where ASI demonstrated a new proprietary film production method.
Representative Optimized Conductive Thin Films
Benefits of ASI’s Thin Film Technology
- Uniform conductivity
- Low filler content
- Thinner material with properties equivalent or better than legacy materials
- Great product for pre-pregging
- All the benefits of carbon nanofiber in a closed-form solution
Conductive films and inks are widely used for electrostatic dissipation as well as EMI shielding in electronics, aircraft, and aerospace applications. These materials are typically fabricated using conductive materials such as carbon black and metal flakes. While effective, carbon black requires high loadings in the resin film, and inks can negatively impact the durability of the resultant films and coatings. The use of metal flakes in these types of applications also has limitations associated to high particle loadings required to reach resistivity targets. Furthermore, compatibility with the polymer matrices is a prevailing issue, as well as corrosion. With the growing maturity of carbon nanomaterials (CNM) and large scale production of these materials, it is of increasing interest to utilize (CNM) in conductive films and inks. The potential to achieve low electrical resistivity targets at very low filler loading lies in the high aspect ratio and high electrical conductivity of graphitic nanofibers and nanotubes.
Successful Demonstration of Film Properties During Navy Phase I Research
Through use of nano-scale reinforcements and their proper application, ASI capitalized on the promise of these materials during a Navy Phase I SBIR program to increase the performance of polymeric films which meet all of the Navy’s requirements at a lower thickness (and therefore less parasitic mass) than legacy materials. ASI will build on this success in the Phase II program through proving in the capacity for commercial manufacture.
Significant progress was achieved in the both the formulations of conductive solutions and the film production processing methods. Under this program, ASI identified an effective and synergistic combination of graphitic nanomaterials. The blend of materials was found to balance conductivity and uniformity, while providing control of the percolation threshold and minimization of the loading of graphitic nano-scale additives. Furthermore, both of the selected conductive additives and the selected polyimide resin are all commercially available in large volumes and at low cost. A readily-scalable and effective dispersion protocol for preparing the film-forming conductive solutions was established and verified through dispersion analysis. The ASI-developed process is advantageous in that scaling up production to larger area films will only require purchase and modification of appropriately-sized commercially available equipment as opposed to designing and fabricating custom equipment. Using the equipment assembled for the feasibility study in Phase I, it was found that preparation of robust, uniform films was quite rapid and reliable. The film materials developed by ASI are thinner (less parasitic mass) than the legacy material while meeting, or exceeding, all of the Phase I program goals, thereby enabling weight reduction. These materials also met or exceeded the solvent resistance and bend testing requirements.
Development of more robust conductive thin polymer films will provide benefits to numerous commercial electronics applications as well as commercial aircraft applications. The benefit to Defense applications will be an increase in the lifetime of the conductive thin films compared to materials currently in use and a reduction in weight.
Contact Patrick Lake to learn more about Thin Polymer Films.
Mr. Lake is a Chemical Engineer with experience in growth of VGCF and CNF, and fabrication of high thermal conductivity carbon-carbon composites. Patrick pioneered the development of ASI’s Thin Films under funding from the US Navy. Patrick is currently working under phase II funding from the US Navy to refine the production process and develop new applications for the material.