Alignment Precision
Laser drilling systems on high-density circuit boards must find the exact center of buried copper pads. The microvia target acquisition process uses optical cameras to identify fiducial marks on the inner laminate layers before drilling. This alignment secures the laser’s position relative to the target, reducing the risks of hole breakout and misregistration.
Distortion Compensation
Since laminate materials contract and stretch during lamination, the target pads are rarely at their nominal coordinates. The drilling system’s software analyzes the scanned positions of the fiducial markers and shifts the drill coordinates to compensate for local panel distortions. This dynamic correction ensures that each laser pulse strikes the center of its target pad, maintaining consistent connections across all layers of the board.
This local scaling is necessary when manufacturing dense high-density boards, as uniform panel-wide offsets do not account for localized material shifts.
Inspection Criteria
Post-drilling inspection confirms that the laser-drilled hole sits within the required boundary of the target pad. Any drift in the microvia target acquisition causes thin walls or breakout, which degrades the mechanical strength of the plated via. Maintaining this precision is necessary for high-density designs where the target pad diameter is only slightly larger than the microvia itself.
