Registration Vector Analysis in Sequential High Density Core Lamination
Sequential core lamination registration requires X-ray target vector mapping and dynamic affine drill scaling to maintain zero breakout microvia alignment.
Core Distortion
Material Deformation
Substrate movements during the lamination process result in the permanent alteration of circuit features from their intended design coordinates. While laminating multilayer boards, core distortion occurs as the heat and pressure of the cycle release internal stresses within the glass reinforced laminate. This phenomenon causes the copper patterns on inner layers to shift or shrink relative to the outer layers.
Process Variable
The resin system in the laminate liquefies and then hardens, exerting force on the woven glass fibers and the copper foil. This core distortion varies based on the copper distribution across the panel, as dense areas resist movement more effectively than clear resin areas. Laminators observe different rates of movement depending on the thickness of the core and the orientation of the glass weave.
Consistent cooling rates help to minimize the unpredictability of these changes. Press parameters like pressure ramp rate and dwell time are adjusted to stabilize the material.
Registration Impact
Drill targets placed at the corners of the panel allow the manufacturer to measure the extent of the movement after the board leaves the press. If core distortion exceeds the specified limits, the drill bit will fail to hit the center of the internal pads.