Laser drillable prepreg alternative to coated copper for HDI applications

摘要

There is a contingent in the industry that feels reinforced substrates are needed to meet the performance requirements of HDI microvia technology. Concerns that non-reinforced resin coated foils, or non-woven substrates, may not provide the thickness control and predictability of movement and reliability needed to meet the next generation of infrastructure board designs, which must include microvias. Conventional woven glass offerings used for prepregs which have been fabricated using laser drilling technologies have yielded inferior hole wall quality and require higher pulse counts making them an undesirable alternative to some. Development of a laser drillable glass fabric has given new hope to conventional prepregs, offering a better fit to all attributes desired in materials for HDI microvia applications. Clean hole quality at fewer pulses than conventional glass fabric, better dimensional performance, dielectric yield control, reduced cracking, ease of handling and storage and availability make the new generation of laser drillable prepregs an attractive alternative where supported substrates are desired. This paper will discuss the attributes and short falls of laser drillable prepregs in comparison to other material types commonly used in HDI applications.