1. Consider Impedance and Signal Integrity:

– Due to thin insulating isolation layers, the impedance between layers of 10 or 12-layer boards is low, offering excellent signal integrity if delamination and stacking issues are absent.

– Designing 12-layer boards with a 62-mil thickness is challenging, and only a few manufacturers can process them.

2. Layer Allocation in 10-Layer Design:

– It is not optimal to allocate the middle layers for routing the signal lines, and it’s crucial to have the signal layer adjacent to the ground and power layers to ensure a good path for signal and loop current.

– Recommended routing strategy: alternate the routing direction along different layers for tight coupling between the forward and return paths of the signal.

3. Importance of Via Holes and Layer Pairing:

– Routing signals through via holes and ensuring tight coupling between signal and loop currents for minimal inductance, high capacitance, and good electromagnetic shielding performance.

– When signals must leave the current pair of layers to other wiring layers, ground vias should be placed nearby to facilitate smooth return of the loop signal.

4. Design Considerations for Power Layers:

– Placement of multiple power and ground layers to evenly divide current and reduce transient voltage, in turn minimizing EMI.

5. Summarizing the Key Principles:

– Highlighting the important design concepts and principles for effective PCB design to ensure bypass and decoupling of power busbars and minimize transient voltage on power or ground planes. By adhering to these principles, engineers can design circuit boards that consistently meet design requirements, especially crucial with IC rise times becoming shorter and essential for solving EMI shielding problems.