Though the PCB design flow can be split a number of ways, it is best to think of it as having two fundamental stages: Prototyping and Product Development.
Prototyping occurs at the earliest stage of design and involves individual engineers researching how to define a certain system or application. The experimental nature of this stage is fundamental in being able to develop hardware that can meet specifications. When the design has been validated, it can be passed onto the latter stages of the design flow (i.e. product development). The ultimate goal of the prototyping stage is to have a successful product that is accurate, efficient and meets specifications. You want to accomplish this with as few prototype iterations as possible to maximize time and resources.
Product Development is about making a PCB ready for a final application. The prototype has already met the design specifications (filtering, amplification, acquisition, measurement etc…) and it is now ready to take that design and to implement it using the best practices in design. Most companies have individuals that are layout experts, and are involved in product development. During this design stage, you are developing for manufacturing and as such are concerned about increasing product yields and decreasing manufacturing re-spins.
PCB Design Flow - Step 1 - Part Research & Selection
PCB Design Flow - Step 2 - Schematic Capture
PCB Design Flow - Step 2b - Simulation
PCB Design Flow - Step 3 - Board Layout
PCB Design Flow - Step 4 - Verification & Validation
It is important to understand this difference as there are various tools that are best fitted to each of these stages of the design flow. Although for product development board layout specialists are available, the researcher is generally a domain expert. A domain expert needs to be able to quickly design, without being an expert in schematic capture, simulation or layout.
For example, for prototyping you need to be able to:
Define a circuit schematic quickly
You need to validate circuit behavior with advanced analysis techniques
Transfer a schematic to layout easily
Validate the behavior of the design accurately
For the PCB Design fundamentals we will focus on the prototyping stage and help you (the individual designer) to learn more about developing a PCB prototype.
We can split the prototyping stage pictured above (Design > Prototype > Validate) into four steps: Part Research and Selection, Schematic Capture and Simulation, Board Layout, and Verification and Validation.