Abstract: Chemical vapor deposited (CVD) diamond film has bright application foreground in many high-tech fields for its a series of outstanding properties. The temperature field distribution of CVD diamond film laser drilling process is different from other materials because of its diamond graphitization taking place during the process. As a result, studies on thermal field distribution have great importance on both the investigation of the processing mechanism and the optimization of drilling parameters. In this paper, a thermodynamics model considering graphitization of CVD diamond is built at first. Based on the model, FEM simulation research is conducted on laser drilling CVD diamond film. Through simulation the temperature field distribution and the degree of diamond graphitization are presented. Besides, the relation between laser drilling results (average removal rate per pulse and graphitization depth) and laser drilling parameters (laser energy, pulse width, repetition rate) is investigated. It is found that average removal rate per pulse and graphitization depth increases with the increase of laser energy, pulse width, repetition rate, with the laser energy as a key factor. Simulation results show that when choosing the drilling parameters with laser energy 0.5～1.6 J, the pulse width 300～800 ns, repetition rate 30～60 Hz, we could obtain high efficiency together with small heat-affected zone.

Key words: CVD diamond film;Q-switched pulsed Nd:YAG laser;laser drilling;temperature field;FEM