Most (or most likely all) of my PCB stack-ups are 1.6mm (62 mils), but I am now in the need of doing a thicker PCB due to mechanical reasons (we need a thicker board so the customer doesn't break it easily when pressing on buttons).
I was thinking of going up to 2mm (78 mils), but I'm not sure if I should just increase the dielectric thickness in the middle of the board?
My board:
Layers: 4 (L1 = signal, L2 = ground plane, L3: power plane and some signals, L4: pads for buttons).
I have a pair of differential signals on L1 that I need to control their impedance to 90ohms, this is my original thinking:
Top Solder: 0.4mils
L1 - Copper: 1.4 mils
Dielectric 1: 6.7 mils
L2 - GND plane: 0.7 mils
Dielectic 2: 60.3 mils
L3 - Signal and VCC: 0.7 mils
Dielectric 3: 6.7 mils
L4 - Copper: 1.4 mils
Bottom Solder: 0.4 mils
Total: 78.7 mils or 2mm
I just simply added the extra thickness to the center of the board, but I'm not sure if that is the ideal solution
. All feedback is appreciated.