The Definitive Guide to an Electronic Assembly Design Review / 9
As the speed and complexity of electronic components continues to climb, the importance of a detailed
PCB analysis in the overall design process has become more and more important. The common practice of
leaving the vital PCB stack-up design in the hands of the PCB fabrication company's fabrication engineers
carries with it significant hazards. A much better approach includes empowering the design team to
provide the fabricator with all the information necessary for creating a printed wiring board (PWB) that is
fully compliant with the specifications
For example, depending on the product, designers may need to consider the surface finish attributes
applied by a circuit board fabricator. The surface finish influences the process yield, the amount of rework
necessary, field failure rate, the ability to test, the scrap rate, and of course, the cost. Designers can be led
astray by selecting the lowest cost surface finish only to learn that the total design cost is much higher. The
selection of a surface finish should be completed with a holistic approach that considers all important
aspects of the assembly, including:
Cost sensitivity
Volume of product (finish availability)
Tin lead solder (SnPb) or load finish (LF) processes
Shock/drop concerns
Cosmetics concerns
User environment (corrosion concerns)
Fine pitch assembly (<0.5 mm)
Wave solder required (PCB > 0.062")
High yield in-circuit test (ICT)
5
PCB Analysis
