A Micro-energy w-EDM Power Source Based on High-frequency Spark Erosion for Making Diamond Heat-Sink Arrays

Diamond is a typical super-hard material with very high thermal conductivity. This makes is highly suited to heat dissipation from electronic microchips. The stability of its chemical lattice structure, however, means it has no free-electrons and a high melting point, making machining of diamond difficult. In this study, a micro-energy w-EDM (wire-Electric Discharge Machining) power source with dual-capacitance is designed for using high-frequency spark erosion to precisely cut boron-doped nano-polycrystalline diamond (B-NPD) material. The power source design consists of a dual-capacitance circuit, a programmable logic circuit (PLC), and a metal–oxide–semiconductor field-effect transistor (MOSFET). By utilizing a high-frequency switching dual-capacitance circuit, each capacitor has enough charge/discharge time to create a micro-energy pulse train of uniform iso-pulse on-time (τ_on) and iso-pulse peak current (I_p). Material removal occurs rapidly so that micro-quantities of diamond are readily removed to reduce the probability of thermal damage and graphitization. The technique allowed successful machining of a highly consistent plate-finned diamond heat-sink array and trapezoid-pillar diamond heat-sink array. Furthermore, manufacturing using the designed low-energy power-source is highly efficient. To estimate machining efficiency in terms of the content of charge per unit volume per unit of time in diamond cutting, “Charge Density (CD)” is proposed and examined as an evaluation criterion. The following are all discussed in detail: work frequency, work capacitance, wire-electrode number and short-circuiting percentage, heat-erosion on fins of different thicknesses, and fin efficiency.