Alignment Geometry
Physical configuration of registration posts in a lamination fixture or an imaging machine maintains the relative position of every layer in a stack. A tooling pin layout defines the number and placement of these pins to prevent the panels from shifting during processing. Engineers typically place these points at the corners or the midpoints of the panel borders to provide maximum mechanical constraint.
Geometric Placement
Geometric placement of the pins allows the material to expand and contract from a fixed center point to avoid edge biased shifting. When the tooling pin layout uses a four slot configuration, the panel can move along the axes without causing internal stress or buckling. This freedom is necessary.
Resin and copper expand at different rates when they are heated to nearly two hundred degrees Celsius, which often causes layers to shift if they are not constrained correctly. If the pins were placed too close together, the panel might bow, which would lead to poor registration during the subsequent drilling phase. Solid steel pins with a diameter of three or four millimeters are common for ensuring high repeatability across thousands of production cycles.
Layer Stability
Secure pinning prevents the heavy copper layers from sliding against each other during the fluid stage of the resin flow. Accurate layouts are essential for maintaining the vertical integrity of the stackup.
