Applied Embedded Electronics

Chapter 11. Schematic to PCB

Prior chapters dealt with various pieces of the system, and the discussion now moves to organizing those pieces into an understandable and documented schematic. From there, the design of a printed circuit board (PCB) is examined, along with what’s needed to commercially build a PCB loaded with components.

The PCB design process starts with selecting the components and defining the schematic. Then a detailed bill of materials (BOM) can be created. The selected components require suitable connection footprints for mounting to the PCB. These can be pulled from existing vendor libraries, or for less common devices they can be designed from scratch.

Depending on PCB size and circuit complexity, a suitable set of PCB layers (aka layer stack-up) can be defined. A strategy for optimized component placement and connections is explored, with information on many of the “special attention” items necessary for a PCB. These include transmission line design, Kelvin sense connections, low-impedance power decoupling, electromagnetic interference (EMI) and electrostatic discharge (ESD) issues, specialty vias, thermal relief methods, and others.

PCB design, fabrication, and component assembly doesn’t follow a single set of fixed rules. Every contract PCB manufacturer (CPM) has somewhat different capabilities and can provide rules suitable to their capabilities. Consequently, frequent referrals are made herein to information needed from the CPM. Both a design rule set ...