People got used to a steady increase in performance of electronic devices. Increasing resolution of displays, data transfer rate, growing volume of data storing are the shining examples of these processes. Electronics takes control over more and more functions in the most critical spheres of our life, including transport, medicine, and power industry. It means also that the volume of requirements imposed on hardware devices increases as well, encouraging the improvement of the hardware design quality in general.
Since a Printed Circuit Board (PCB) is the key pillar of any device, influencing the efficiency of an end solution, it is very important to put an increased focus on existing approaches to a development of it’s most complex nodes: routing of a power supply system and accuracy of high-speed traces.
The review of a PCB layout design is one of the most transparent instruments in the way of increase the quality of a product. The procedure allows for manufacturers of electronic devices to draw conclusions about conformance of a layout design to the international standards and requirements, common for manufacturing companies and assemblers all over the world.
Generically, depending on the verification goals, we distinguish two main approaches:
- Debugging verification - the procedure with the main goal to improve the overall quality of a PCB layout design by excluding parasite rudiments from a topology. Most times such a review can be conducted after completing a routing of a PCB by the same layout design engineer. Although the involvement of third-party specialists usually makes it possible to find a number of nodes, for which a methodology of routing can be improved still.
- Pre-production verification of a PCB layout design with the aim of receiving an independent professional opinion regarding the quality of a design. To conduct this type of analysis engineers need a project of the board and up-to-date bill of materials (BOM). The inspection can prevent risks of unexpected issues during the assembly of a board, it minimizes parasites which are possible as the result of incorrect routing. In certain cases an analysis of a PCB layout design can bring up to light facts of irrational usage of expensive solutions and technologies or even excessive number of used PCB layers. Obviously, the quantity and severity of mistakes and inaccuracies declared in the final report can become an indicator of the professional level of a PCB layout designer in certain cases.
Before involving a third-party vendor into a verification procedure of a newly developed PCB layout design we recommend to specify in advance a volume of the verification job that has to be performed. The list of aspects that can to be appreciated is quite long, for instance:
- verification of stack-up;
- verification of high-speed traces for compliance with the international standards and recommendations (DDR, Ethernet, PCIe, etc.);
- verification of a layout with for compliance with requirements presented by manufacturers of ICs;
- verification of reasonability of implementation of the technologies influencing a fabrication cost of a PCB (blind and buried vias);
- selective or a full quality verification of PCB footprints, including their compliance with requirements of IPC and recommendations of component manufacturers (DFA check);
- PCB analysis from the manufacturability point of view (DFM check);
- Signal Integrity analysis (SI), Power Integrity analysis (PI);
- verification of traces and a PCB floorplan (Placement check) in the context of power dissipation (Thermal analysis).
A detailed report with a list of found issues has to be delivered to an ordering customer as the logical result of PCB design layout analysis. Design companies providing such investigations are capable additionally of providing their estimation of efforts required for troubleshooting problems listed in a report.
In conclusion, we would like to put a special attention to PCB layout designs made with the help of automated routing software solutions. Clearly, the main advantage of this approach is the speed of development. However, the level of automated routing does not allow in most cases to gain a high-quality product. Moreover, the expenses on further manual correction of the designs may be higher than the development of a complete PCB layout from scratch manually.
Electronics development company Edality provides full spectrum of services in the field of PCB layout design and verification.