PCB Stackup Design Considerations for Intel® FPGAs

ID 683883
Date 6/28/2017
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1.1. PCB Stackup Construction

A typical PCB stackup is constructed from multiple alternating layers of core, prepreg, and copper foil materials heat-pressed and glued together.
Figure 1.  Cross-section of a 14-Layer PCB Stackup

The PCB manufacturer purchases the core material as a thin dielectric with copper clad foils bonded to both sides. The core’s dielectric is a cured (hardened) fiberglass-weave material with epoxy resin that acts as an insulation layer between the copper foils. For core materials, the foils form the internal copper layers (signal or plane) in the PCB. Prepreg is an uncured fiberglass-epoxy resin weave that acts as the insulation between core layers and is the gluing agent for the cores. During the PCB manufacturing process, multiple core and prepreg layers are combined with a top and bottom copper foil sheet. The combined layers are heat-pressed together to build the complete PCB stackup. The heat-press treatment cures the prepreg and binds all the different layers together to form the PCB.