Wafer-Based Thin-Film Circular Cutting Edges at High Speed
T. Schelling (TU Delft - Mechanical Engineering)
R.A. Norte – Mentor (TU Delft - Dynamics of Micro and Nano Systems)
R.A.J. van Ostayen – Graduation committee member (TU Delft - Mechatronic Systems Design)
M.K. Ghatkesar – Graduation committee member (TU Delft - Micro and Nano Engineering)
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Abstract
This thesis investigates whether a wafer-defined circular blade can realise a mechanically robust cutting edge at thin-film thickness scale and perform first material removal under rotation. The concept uses a silicon annulus carrying a deposited film. Selective substrate removal near the outer perimeter releases a circumferential overhang whose thickness defines the nominal kerf scale, while overhang length governs achievable cutting depth. The work is structured around four challenges: reaching the minimum cutting-edge speed with acceptable run-out, fabricating annular blade blanks, selectively underetching the rim while preserving mounting geometry, and integrating the system to demonstrate cutting.
A practical spindle operating envelope was established in which the blade reached the minimum target speed while operational displacement remained predominantly rotation-synchronous and below the realised overhang range used for survival and engagement trials. LS-Precess femtosecond-laser cutting enabled repeatable fabrication of 525 µm-thick silicon annular blanks, and a lid–base sacrificial masking concept enabled selective SF₆ underetching and controlled release of SiO₂ rims while preserving hub-bore integrity when the lid remained intact. In the integrated demonstration, released SiO₂ rims survived operation at and above target speed and produced a continuous kerf in rigid ABS under incremental approach at N = 17.7 kRPM, with measured trench depths of 11.72 µm to 14.71 µm and a central kerf width of ~46 µm.
The main limitations are that rigid cutting was attributable primarily to the rear-side ~10 µm rim, sustained controlled engagement of the front-side ~4 µm ultra-thin rim remains unproven, and circumferentially continuous ultra-thin a-SiC edges were not reliably achieved within the present process window.