The same piece of material can be tested in two different tests and achieve two different Dk values, and both values may be correct. One reason why that statement can be true is since most materials used in the PCB industry are anisotropic, which means that the Dk is not the same on different axes. Some test methods will evaluate the material in the z-axis (thickness axis) only and other test methods will evaluate the x-y plane of the material for the Dk property. When a material is anisotropic, there should be a different Dk in the z-axis than in the x-y plane.
In electronic systems, signal transmission exists in a closed-loop form. The forward current propagates from transmitter to receiver through the signal trace. Meanwhile, the return current travels backward from receiver to transmitter through the power or ground plane directly underneath the signal trace that serves as the reference or return path. The path of forward current and return current forms a loop inductance. It is important to route the high-speed signal on a continuous reference plane so that the return current can propagate on the desired path beneath the signal trace.
Flexible circuits are known by a few different names depending on one’s global location and language: flexible printed circuits, FPCs, flex circuits, flexi circuits, flexibles, bendables and a few others that are...
Susy Webb: Training the New Generation of Designers, a conversation with Susy Webb
Help Wanted: PCB Design Layout Specialist, by Mike Creeden, CID+, MIT
Mentor Preparing for Next-Gen PCB Designers, a conversation with Paul Musto
Where Have All the Designers Gone (and Who Will be Taking Their Place)? by Tim Haag
In With the New at Cadence, a conversation with Bryan LaPointe and Dan Fernsebner