High-level PCB specifications
The first step in the process is the creation of high-level specifications. Here is where all the different design disciplines, marketing, electrical, and mechanical decide on the product details and schedule. Once a clear vision of the product is complete, the different disciplines are assigned their work items. Since we are focused on the PCB design process with this article, we will follow that path.
Inside the engineering disciplines, there are many subgroups attached to it. Each of these groups has a specific role in the successful completion of the design. Initially, there are many parallel paths. The design engineers are identifying new components that will be needed and pass this information to the PCB librarians to create and add to the library. The signal integrity (SI) engineers will be creating their models as well as defining the stackup and constraints that will be needed. The PCB designers will be working with the mechanical engineers to define the exact dimensions of the PCB as well as identify any critical component areas. For high-volume designs, this is also a very good time to start looking at assembly panelization considerations as it could affect the final board size.
Simulation and schematic entry
As that above work continues the PCB design process next steps include simulation as well as schematic entry. These two activities will be the driving force for the actual PCB design to come. There are review loops built into this process to help identify any potential issues.
As the simulation and schematic processes wind down it’s time for the PCB Designer to start the actual layout of the PCB. This is where all the data from the SI engineers, mechanical engineers, manufacturing engineers, test engineers, and electrical design engineers come together. Now that the designer knows the outline of the PCB as well as the PCB stack up and constraint information it’s time to start placement of the components. After the initial placement is complete there is a review with the stakeholders to confirm that any mechanical restrictions, as well as any manufacturing concerns, are addressed. Many companies at this stage would also use Valor NPI to analyze the component placement to assure the design is manufacturable from an assembly perspective. Importing the BOM and using the Valor Parts Library can be used to check that all alternate components are compatible. Solderability analysis at this stage can catch any issues that normally are not discovered until prototyping the assembly.
Critical signal paths
The next milestone is routing any critical signals. During this step there are reviews with the electrical design engineers as well as board-level simulations being run by the SI engineers. Again, Valor NPI should be used at this stage to analyze the critical routing to assure that it meets all the requirements of the fabricator(s).
Routing the remainder of the design is next. Once completed it’s on to cleaning up the design. Adjusting silkscreen and solder mask along with creating fabrication and assembly drawings is the next order of business.
The last major process step is to run a complete Design for Manufacturing (DFM) review. This should include both the Design for Fabrication (DFF) and Design for Assembly (DFA) analysis. All the stakeholders are present for this final review. Using Valor NPI throughout the entire PCB design process will minimize any design issues so that the PCB will be ready for the final step, once the DFM analysis has been finalized and has the approval of all stakeholders. The design can now be released to manufacturing as a clean design.
Accelerating new product introduction with Valor NPI
DFM is no longer a post-layout process in PCB design. It is now considered throughout the shift-left concurrent design flow. From test-point definition and validation to DFM analysis during layout, designers can eliminate errors before PCB assembly. DFM validation ensures a seamless and error-free design-to-manufacturing hand-off.