Understanding Glass Weave Effects in High Speed Differential PCB Stackups
Glass weave skew causes intra-pair phase delay in high-speed differential pairs, requiring spread glass, dual-ply prepreg, or off-axis panel rotation.
Panel Scrap Arithmetic
Panelization Yield
Manufacturing efficiency in printed circuit board fabrication relies on maximizing the usable area of a standard production laminate panel. The panel scrap arithmetic is the calculations used to determine the percentage of material that is wasted during the routing and singulation processes. Fabricators use this method to optimize the arrangement of individual boards on the panel.
High material utilization directly reduces the raw cost per board.
Geometric Calculation
Calculating the waste requires subtracting the combined area of the individual boards and test coupons from the total area of the production panel. This formula accounts for the margins required by the automated handling equipment and the width of the routing channel. For example, a standard eighteen by twenty-four inch panel has an area of four hundred thirty-two square inches.
If the laid-out boards occupy three hundred square inches, the remaining area represents the scrap material.
Financial Consequence
High scrap percentages inflate the price of the manufacturing run because the customer pays for the discarded material. Designers can modify the dimension of the board to fit more units on a single panel. This change lowers the waste per panel.
Choosing the correct panel size is a critical step in high-volume production.