*this is a 4 layer board, sig gnd gnd sig
The other day I was faced with the option of having to choose between two stackups.
One stackup has thick dielectric layers (0.2mm) between sig/ref meaning the coupling would be worse and the traces @ 50/100 ohms would be thick
The other stackup has thin dielectric layers (~0.1mm) between sig/ref where the coupling would be great, and the traces would be thin
How much does it matter if the reference plane is 0.2mm (far)away but the traces have the correct width/impedance? Does signal integrity get affected?
I know there are many high frequency RF boards that use 2 layers with thick 50 ohm traces. Its easier to get the right trace width for thicker traces, they are more immune to thermal expansion and mechanical vibrations as well.
I want to use the swra117d antenna which is designed for a 1mm PCB with a dielectric of 4.5. My manufacturer (JLC) has 2 free impedance controlled stackups the problem is that one has a dielectric of 4.4 but with thick 0.2mm dielectric layers (worse coupling, thicker traces), and the other one has a dielectric of 4.1 (>>4.5). Both stackups are 1.6mm total PCB thickness, which one should I use? I could use a chip antenna but I really would prefer a trace one