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58 The PCB Magazine • February 2016 to the limitation of a UV laser's pulse energy and frequency, percussion drilling has not been widely applied at the production levels. In order to make a breakthrough considering the above limitations, an optimal beam delivery system has been developed utilizing an unique and sta- ble beam-shaping technology which opens up the ability of UV lasers to reach downwards to <50 micron via diameter. This innovative design is able to deliver a flat-top energy distribution across the laser beam face from the laser to the drilling point with minimum power loss, which allows UV la- sers to perform percussion drill on HDI boards with high throughput. Figure 2 shows a 50 mm diameter microvia on half-ounce copper cre- ated by UV laser percussion drilling. Those vias can be completed by UV lasers to form straight taper shapes in dielectric materials, or alterna- tively become conformal windows for CO 2 la- sers to create taper shaped microvias. In addition, the beam delivery technology retrofits to installed laser systems so that the technology can be leveraged to meet further Figure 1: UV laser drilling scheme with beam-shaping technologies. Figure 2: 50 mm diameter microvia on HDI boards drilled by UV laser percussion. the next step: teChnology that's driving sMaller MiCrovias