Does anyone have any advice on routing some high speed signals on flex PCBs? I'm looking at jlcpcb because of the low cost but I'm having difficulty getting impedances to be decent.
min trace width/spacing = 4/4 mil = 0.101/0.101 mm
ε = 3.3
Is this feasible with this stackup? I'd like to do a 1 oz pour because of power traces, but there's also 0.5 oz (18um) and 0.33 oz (12um).
For the differential signals, when I'm doing impedance calculations, I can get to roughly 70 ohms using W=100um, S=200um. I don't think this is good enough. I think I can get away using a 0.33 oz pour but then I'm worried about the power pins.
And for the power traces, I'm needing 2.2mm, which is reasonable for the pins on a USB-C connector. But if I try using the 0.5 oz or 0.33 oz pour, it gets to be 4.2 mm and 6.3 mm, which seems impossible given the pins are tiny and very closely spaced together. Even with vias to the bottom layer, this seems problematic.
Anyone have any advice here? This is just for a hobby project, so I'm really not looking to change fabs because of costs.
it looks like changing the substrate would be easiest from a design standpoint but there are ways around using a thin core.
you could try ditching the ground plane on the other side and using a single plane coplanar wave guide.
about the power traces: can you not use a slightly wider trace on the run and then match to the shape of the connector with a gradual taper near the end?