Prepreg Rheology Control in Thin Core Laminate Stacks
Precise control of prepreg minimum viscosity and press temperature ramp rates prevents core squeeze out and micro voiding in thin laminate stackups.
Scale Factor Registration
Dimensional Compensation
Mathematical adjustments are applied to circuit board artwork to account for the predictable shrinkage or expansion of materials during fabrication. This scale factor registration ensures that the copper features on different layers align perfectly after the lamination heat cycle. By slightly enlarging or shrinking the image, the fabricator compensates for the physical changes in the laminate.
Image Adjustment
Different material types and copper distributions require unique offsets in the X and Y axes. Applying the correct scale factor registration allows the drill bit to hit the center of every internal pad across the entire panel. Data for these adjustments is collected by measuring production panels and comparing the actual dimensions to the original design files.
This process is essential for high density interconnect boards where the margins for error are extremely small.
Alignment Verification
Laser direct imaging systems use these factors to warp the circuit pattern in real time based on the detected position of targets. If the scale factor registration is calculated incorrectly, the resulting mismatch between layers will cause electrical opens or shorts. Final quality audits include cross sectioning to verify that the layer to layer alignment stays within the limits defined by IPC standards.