A blog by Michael Nopp. As I wrote in my last blog, ‘When to flex?’, flex and rigid-flex are becoming increasingly popular in PCB design. But what are some of the things you should look for when choosing a flex design tool? First, you need a flex-aware tool that enables easy and intuitive assembly definition. With PADS Professional you can quickly define unique stackup objects, such as stiffeners and cover layers, and change stackups by board outline.