I just read this entire forum and every single question beyond “beginner PCBs” is ignored by Seeed. I, as others, am interested in designing 50 ohm traces on mutli-layer boards but we cannot get any information for doing this. I am posting this in hopes of getting the required information. If there is no response from Seeed then there is no alternative but to go elsewhere for PCBs.
Here is what I have sent to “tech support” as the minimum information to do a 4 layer PCB with 50 ohm traces on the top or bottom layers of a 4 layer PCB:
“I have ordered PCBs from Seeed before but have a question on an upcoming order of a 4 layer board. I assume if I order a 4 layer board that there is an inner core and the outer layers are foils. I need the layer thickness of the stackup, specifically the prepreg thickness between the top copper and next inner copper (Top copper of core) and the bottom copper and the next copper up (bottom copper of core). Also required is the dielectric constant (er) of the specific FR-4 being used. Please provide the layer thicknesses or a link where it can be found plus the dielectric constant. Thanks.”