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Excimer lasers are finding increasing use in the electronics manufacturing industry. In contrast to other types of laser processing in which material is removed by localised heating, excimer laser processing involves a non‐thermal ablative material removal mechanism. This is due to the ultra‐violet output and short pulse duration of these unique light sources. The result is a high precision means of patterning thin dielectric films, removing such films from metal substrates, or removing thin metal films from underlying dielectrics. Through proper selection of operating parameters it is possible to achieve smooth sidewall profiles with selectable amount of taper while leaving the surrounding and, in the case of film removal, the underlying material virtually untouched. This paper will review the growing use of excimer lasers in applications such as the skiving of access holes and windows in flexible wiring, the drilling of via holes for multilayer boards, the stripping of microwires and other chip bonding applications. The differences between excimer laser processing and conventional laser based techniques will be highlighted.

In the past three years, microvia drilling using laser technology has become the dominant method of producing blind vias smaller than 150μm. The ablation characteristics of the materials used in the manufacture of PWBs can be divided into three categories: organics, glass, and metals. Organics are composed of resins and epoxies commercially available from a variety of vendors. Two types of resins that are typically used for microvia formation in the telecommunication applications are resin coated copper foil^® (RCC or RCF) for subtractive PCB process, and thermal‐curing resin (TCR) for additive PCB process respectively. This paper details the basics of UV YAG laser capabilities, alignment techniques, plating tests, reliability tests, manufacturable microvia design rules, and production experiences.