Micropore processing technology and quality evaluation of HTCC based on UV picosecond laser

The High Temperature Co-fired Ceramic (HTCC) substrate boasts advantages such as high structural strength, high thermal conductivity, and good chemical stability, thus showing broad application prospects in high-power microcircuits. As the circuit board material, it is necessary to use mechanical or laser drilling on the raw porcelain, and the aperture of through hole and position accuracy directly affect the yield and final electrical properties of the substrate. In recent years, laser processing technology has the advantages of high precision, high efficiency, stable performance and no contact, which increasingly become one of the most critical processes of multi-layer ceramic packaging technology. In this paper, the ultraviolet (UV) picosecond laser with pulse width of 15 ps was used for HTCC drilling with thickness of 0.14mm. The laser has a maximum power of 30W at a repetition rate of 600 kHz, a spot size of 20 μm after focusing, and a wavelength of 355nm. By optimizing the process parameters, including laser power, frequency, scanning speed, and repetitions, a minimum through-hole with diameter of 100 μm, with an accuracy of ±5 μm for entrance and exit holes were achieved. Under optical microscope, roundness, taper, and Heat-Affected Zone (HAZ) of hole under different conditions were obtained and analyzed. These results prove that ultra-fast laser processing can be an efficient HTCC drilling technique.