Freeform fabrication of functional microsolenoids, electromagnets and helical springs using high-pressure laser chemical vapor deposition

This paper reports recent progress in the use of 3D-LCVD as a viable micromanufacturing tool for helical microstructures. Freestanding fibers of diamond-like carbon were grown from ethylene at linear rates of up to 3.5 mm/s. Helical carbon fiber coils were also grown, yielding highly elastic springs which may be used in low-frequency-response accelerometers, seismometers, and switching devices. Continuous fibers with diameters as small as 5 /spl mu/m were obtained at ethylene pressures of 3 atmospheres. Freestanding conductive coils of polycrystalline tungsten and tungsten carbide were also grown at axial deposition rates of up to 175 /spl mu/m/s using mixtures of WF/sub 6/, H/sub 2/, and C/sub 2/H/sub 4/. Single-crystal tungsten needles of square cross-section and hexagonal tungsten carbide crystals were obtained with specific WF/sub 6/-H/sub 2/-C/sub 2/H/sub 4/-He mixtures. The WF/sub 6/-W/sub 2/-He-Xe system was studied to determine the effects of buffer gas molecular weight on the potential for natural convection and deposition rate enhancement during tungsten growth. In addition, high field-density microsolenoids 100 microns in diameter were written on boron fibers using laser direct writing. Tungsten lines were drawn about silicon-coated Co-Fe-Si-B magnetic cores from a mixture of WF/sub 6/ and hydrogen, yielding prototype microelectromagnets.