Laser Ablation
High-energy ultraviolet light pulses remove material from printed circuit board substrates to create blind or buried vias. Dynamic laser drilling modulates the pulse frequency and beam position in real time to maintain a uniform hole wall quality across varied copper thicknesses. This method compensates for local thermal fluctuations during the ablation cycle to prevent taper in the finished geometry.
Constant feedback loops adjust the optical path to ensure the ablation front remains perpendicular to the laminate surface.
Processing Control
Thermal management determines the accuracy of the aperture dimensions during the transition through the dielectric layers. Dynamic laser drilling regulates the power intensity of individual pulses to avoid excessive carbonization of the resin matrix. High scan speeds require precise synchronization between the galvanometer mirrors and the pulse trigger signal to prevent ovality in the bore.
Control systems monitor the back-reflection energy to verify the completion of the drilling event before the beam moves to the next coordinate.
Acceptance Criteria
Electrical continuity tests confirm that the interconnection between conductive layers remains sound after the formation of the hole. Manufacturers verify the registration of the drill location against the target pad pattern to ensure the copper capture remains within defined tolerance bands. Cross-sectional analysis of a sample coupon validates the hole wall roughness and the presence of resin smear.
Proper operation produces interconnects that withstand the thermal stresses of the reflow process without cracking the plated copper barrels.
