<azonenberg>
iirc it's $10/in^2 for 2 layer with enig. They use flex soldermask instead of coverlay and do not support stiffeners, but if you can live with that stackup you can do a 2-layer stackup with ground
<azonenberg>
then transition to whatever edge fingers you need to mate with a connector
<Degi>
coverlay?
<azonenberg>
Most flex stuff doesnt use a lithography-defined mask like rigid PCBs do, although flexible masks do exist
<azonenberg>
coverlay is a polyimide sheet, basically thick kapton tape, that's laser cut and laminated to the substrate
<azonenberg>
it's more flexible and often has better dielectric properties than soldermask, but since it's applied as a precut solid chunk it has more restrictions than soldermask
<azonenberg>
for example, floating islands of coverlay are not possible to fabricate
<Degi>
Interesting
<azonenberg>
oshpark uses flex soldermask to be more newbie-friendly
<azonenberg>
I did initial AKL-PT2 prototyping on that stackup
<Degi>
Hm, I think in single ended mode I'd do max. 500 Mbps (more like 200) where a differential layout probably is still okay without too much crosstalk...
<Degi>
Neat
<azonenberg>
Anyway, not saying you can't do it with premade cables
<azonenberg>
Just don't neglect the idea of a custom one as "too expensive" until you run the numbers
<Degi>
Yes, thats true
<Degi>
I mean for the likes of PCIe that would be neat xD
<monochroma>
i have seen PCIe over FFC quite often. and MIPI CSI and DSI is commonly run over FFC
<Degi>
Yes, thats where I got my inspiration from, the FFC for the RasPi cameras, display panels etc.
<monochroma>
i will say they are not particularly good though for SI (from deep experience)
<monochroma>
but.. they get the job done in short lengths
<monochroma>
some slightly nicer systems (IP Cameras) use shielded FFC cables
<monochroma>
(just a foil tape layer of some sort wrapping one or both sides of a standard FFC
futarisIRCcloud has quit [Quit: Connection closed for inactivity]
<azonenberg>
Yeah for anything in the higher speed regime i would definitely do a custom cable
<azonenberg>
to have a ground plane
<Degi>
Hmh, I guess 1.6 Gbps is kinda on the edge? I mean its 800 MHz BW
<azonenberg>
I think you'd be fine
<miek>
i guess it also depends on what you want to do with it. if this'll be a tool for your pcie stack development, you don't want to be second guessing signal integrity all the time
<Degi>
Nah, nothing that fast
<Degi>
1.6 is just the absolute maximum pretty much, most likely 1 differential and 0.5 single endeed