“Cold” CO2 laser ablation of green-state LTCC—experimental verification of improved model and comparison of various LTCC materials

Abstract

New experimental results in support of the universal mechanism of “cold” laser ablation for machining of various commercial green ceramic materials (LTCC) are presented in this paper. The “cold” ablation model was mathematically formulated and employed to derive an ablation curve equation. The model was tested by CO2 laser ablation of a custom-made green-state alumina ceramic featuring varying binder content. An excellent fit of ablation curve to experimental data was obtained, yielding insight into process energetics and an ablative measurement method of absorption coefficient. The analysis was applied to a sample of commercial LTCC materials. The ablation results were practically identical for all materials in agreement with the prediction of the model, with the high rates of >100 micron/shot at repetition >1 kHz and accuracy comparable with the ceramic grain size. This work provides evidence that the CO2 laser processing has a great potential to become a key low-cost precision processing method for the existing LTCC-based electronic devices (micro-via drilling, general cutting and scribing) and for the new generation of LTCC-based devices comprising micro-fluidics, micro-mechanics, opto-electronics and meta-material structures.