Overview

In the previous chapters we looked at how to use the OrCAD tools to design circuit schematics in Capture, route PCBs with Layout, and postprocess the design for fabricating the board. We have not, as of yet, taken a look at how to design the PCB itself. Chapters 4 through 6 provide an introduction to PCB design. Chapter 4 introduces industry standards related to PCB design.

Not every PCB that is manufactured makes it into service. The ratio of the number of PCBs that enter service to the number of PCBs manufactured is called yield (in %). The higher the yield the better because failed boards cost time and money and produce waste. There are several failure points that can be addressed to increase yield. To have high yield we need three things. First the board has to be manufacturable, second it has to perform properly (signal integrity and quality), and third it has to be reliable (it has to work for the full length of its expected life span).

Being manufacturable means two things. The bare board has to be able to be fabricated given standard fabrication allowances (SFA) and the board also has to be able to be assembled, that is, parts need to be able to be attached to the board with proper solder joints without damaging the parts or the board.

Performance refers to both mechanical and electrical considerations. Mechanically, the board must physically fit into its enclosure and it must be able...