Research on Laser Ablation Threshold and Trepanning Characteristics of High‐Temperature Cofired Ceramics Based on UV Nanosecond Laser

In ceramic packaging, particularly for high‐temperature cofired ceramics (HTCC), precise microhole drilling is critical, with laser trepanning being a key process. This study investigates the ablation characteristics of HTCC using a nanosecond pulsed laser. The single‐pulse and multipulse ablation thresholds were measured systematically. Entry/exit morphology and sidewall features were characterized by laser confocal microscopy (LCM) and scanning electron microscopy (SEM), and the formation mechanisms of various hole morphologies were analyzed. Taper angle and circularity were used as key metrics to evaluate the effects of laser fluence, scan count, and scan ring width. The high microhole quality with a taper below 5° and circularity over 95% was obtained in our experiment. By comparing the actual and theoretical ablation radius, the use of laser fluence for estimating aperture diameter was validated. For different substrate thicknesses, drilling results showed that multiple‐ring trepanning performs best below 1 mm, while filled spiral trepanning is superior above 1 mm. These findings provide an important reference for the practical application of laser microhole drilling in HTCC ceramics.