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In the electronics industry, a “via” is a hole through a material which, when filled with a conductive material such as copper or silver-conductive ink, creates an electrical connection between at least two conductive layers. The simplest form involves two conductive layers separated by an insulating substrate, commonly either polyamide (PI), polyester (PET), or epoxy resin. Vias can be “through” or “blind” type, as shown in the illustration.
Vias are routinely drilled by mechanical methods with diameters 0.020” (0.50 mm) down to 0.004” (0.10 mm). However, as the diameter decreases, the vias become more difficult and costly to produce using mechanical methods. An advantage that laser via drilling (or microvia drilling) offers is that lasers can readily drill small diameter vias from 0.008” (0.20 mm) down to0.001” (0.25 mm).