PCB Stackup Design Guidelines for Performance With OrCAD X

PCB Stackup Design Guidelines for Copper: Traces, Planes, and Signals

Layer Count

• Select the number of layers based on the circuit complexity and functionality. 
• Consider factors such as signal density, power distribution, and noise isolation.

Power and Ground Planes

• Allocate power and ground planes to provide a stable, low-impedance power distribution network.
• Maximize ground plane size to reduce noise, improve signal quality, and facilitate thermal dissipation.

Plane Decoupling

• Place decoupling capacitors near power and ground plane pairs to suppress high-frequency noise and provide clean power to components.

Signal Integrity

• Plan the arrangement of signal layers to minimize signal degradation and maintain good signal integrity. 
• Proper layer ordering, impedance control, and controlled dielectric constants are crucial for managing signal integrity issues such as crosstalk, signal reflections, and impedance mismatches.

EMI/EMC Considerations

• Minimize EMI through careful placement of signal and power planes, using shielding layers if necessary, and use proper grounding techniques.

Signal Layer Ordering

• Determine the order of signal layers to minimize crosstalk and ensure efficient routing.
• Grouping high-speed signal layers and separating them from low-speed layers can help manage signal integrity.

Impedance Controlled

• Design the stackup with controlled impedance for critical high-speed signals.
• This involves calculating and controlling the trace widths, dielectric thickness, and layer separation to achieve the desired impedance values.

PCB Stackup Design Guidelines: Material, Thermals and Manufacturing

Thermal Considerations

• Use thermal vias and distribute thermal planes to manage heat dissipation.
• Place components with high heat production away from more sensitive components.

Manufacturing Constraints

• Note the capabilities and limitations of your PCB manufacturer (minimum track width and spacing, minimum drill size, and material availability).

Material Selection

• Select laminate materials based on electrical performance, thermal properties, and cost.
• Different materials have different dielectric constants, loss tangent values, and thermal conductivities that can affect the overall performance of the PCB.

OrCAD X Feature

How It Helps in Stackup Design

Cross-Section Editor

• Allows designers to add, remove, and configure layers, adjust thickness, material, and surface finish, and import/export cross-section technology files.
• Helps determine the appropriate number of layers based on design complexity and functionality.

Signal Integrity Analysis

• Provides workflows for impedance and coupling analysis, allowing designers to set up and run analyses.
• Aids in managing crosstalk, signal reflections, and impedance mismatches.

Constraint Manager

• Enables setting up and managing rules for power and ground planes, decoupling capacitors, and other design constraints. Ensures a stable, low-impedance power distribution network and effective decoupling.

Via Arrays

• Helps manage heat dissipation by incorporating thermal vias in various patterns. 
• Allows precise control over the placement and pattern of vias, enhancing the flexibility and efficiency of the design process.

Design for Manufacturing (DFM) Checks

• Ensures the design meets manufacturability standards, including advanced constraints related to PCB layer fabrication, assembly, and testing. 
• Helps identify and resolve potential manufacturing issues early in the design process.

Copper Polygon Shape Pour

• Enables the creation and management of copper pours and polygons for power and ground planes, improving power distribution and reducing noise. 
• Helps in creating efficient thermal paths and managing EMI/EMC.