DUE TO ITS effect on both a PCB's electrical and mechanical performance, a sound PCB stackup strategy is vital to creating a reliable PCB. Part one of this two-part series discussed cost-adders. Here, we discuss some added DfM considerations to ensure a manufacturable, flat PCB. Balancing the stackup. PCB warping can occur in a board when a designer is unaware of or does nothing to mitigate mechanical stresses. These can build up when laminating dissimilar layers of copper with various thickness combinations of epoxy-glass laminates. Ensure materials on each side of the PCB stackup centerline are matched. If the stackup is laminated with disproportionate materials and material thicknesses, the unbalanced stackup will experience warping due to built-in stresses incurred after heated lamination and cooling.
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