TY - JOUR
T1 - Enhanced throughput and clean laser drilling with a sacrificial polymer layer
AU - Linden, John
AU - Hoch, Ariel
AU - Levy, Asaf
AU - Sakaev, Igor
AU - Toker, Gil Bernstein
AU - Fogel, Ofer
AU - Hod, Manuela
AU - Zalevsky, Zeev
N1 - Publisher Copyright:
© 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.
PY - 2022/12/1
Y1 - 2022/12/1
N2 - Laser micromachining is the chosen method for vertical interconnect access point (VIA) formation in flex PCB layers. Even so, this method suffers from several inherent physical issues as a result of the intense localized heating causing strong Marangoni convection and the buildup of recast along the VIA upper crater walls while also scattered particle debris and oxidation of copper across the surface. The mitigation of the height and radius of this recast layer is critical for the following build-up process and device functionality and reliability. This is currently a major technology inhibitor to the adoption of flex PCBs for high-power electronics. In this study, we present experimental results showing the use of engineered sacrificial layers that coat the surface of the flex PCB substrate during the laser micromachining process. Optimization of this engineered sacrificial layer resulted in a major improvement in recast quality and debris control as well as reducing the oxide formation while increasing the laser drilling efficiency, attributable to increased surface pressure on the substrate. In this paper, we describe the methods and materials used in the development of sacrificial layers and show the positive impact it achieves on improving and modifying the plasma characteristics throughout the overall laser drilling process.
AB - Laser micromachining is the chosen method for vertical interconnect access point (VIA) formation in flex PCB layers. Even so, this method suffers from several inherent physical issues as a result of the intense localized heating causing strong Marangoni convection and the buildup of recast along the VIA upper crater walls while also scattered particle debris and oxidation of copper across the surface. The mitigation of the height and radius of this recast layer is critical for the following build-up process and device functionality and reliability. This is currently a major technology inhibitor to the adoption of flex PCBs for high-power electronics. In this study, we present experimental results showing the use of engineered sacrificial layers that coat the surface of the flex PCB substrate during the laser micromachining process. Optimization of this engineered sacrificial layer resulted in a major improvement in recast quality and debris control as well as reducing the oxide formation while increasing the laser drilling efficiency, attributable to increased surface pressure on the substrate. In this paper, we describe the methods and materials used in the development of sacrificial layers and show the positive impact it achieves on improving and modifying the plasma characteristics throughout the overall laser drilling process.
UR - http://www.scopus.com/inward/record.url?scp=85145226513&partnerID=8YFLogxK
U2 - 10.1364/OME.467696
DO - 10.1364/OME.467696
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AN - SCOPUS:85145226513
SN - 2159-3930
VL - 12
SP - 4682
EP - 4690
JO - Optical Materials Express
JF - Optical Materials Express
IS - 12
ER -