Beam shaping applications in laser via drilling for microelectronics packaging

Abstract

Within the last five years, laser drilling of microvia holes in high-density electronic packages has been widely adopted for high-volume production. In such micromachining applications, process stability and throughput are key drivers of commercial success. Particularly in the UV, where solid-state laser power is growing rapidly but is still limited, innovations that permit the available laser power to be applied at the work surface more efficiently are of interest. Within the last three years, the use of beam shapers to create round laser spots with near-uniform irradiance at the work surface has been demonstrated. Shaping the irradiance profile has been shown to both increase process speed and improve the quality of the drilled holes, which range in diameter between 20 and 150 µm. This paper gives a brief overview of laser via drilling and presents the Gaussian-to-flattop beam shaping optics used in UV laser via drills, along with the process results obtained.Within the last five years, laser drilling of microvia holes in high-density electronic packages has been widely adopted for high-volume production. In such micromachining applications, process stability and throughput are key drivers of commercial success. Particularly in the UV, where solid-state laser power is growing rapidly but is still limited, innovations that permit the available laser power to be applied at the work surface more efficiently are of interest. Within the last three years, the use of beam shapers to create round laser spots with near-uniform irradiance at the work surface has been demonstrated. Shaping the irradiance profile has been shown to both increase process speed and improve the quality of the drilled holes, which range in diameter between 20 and 150 µm. This paper gives a brief overview of laser via drilling and presents the Gaussian-to-flattop beam shaping optics used in UV laser via drills, along with the process results obtained.