I'm designing a 4-layer board using PADS PCB. Both inner layers are solid ground planes. PADS wants me to select "CAM plane" as the inner layer type and the gerbers are negatives. Is that customary?
The PCB fab wants "right reading when printed" text on every layer. What does this mean?
I think it probably means:
Top Copper = Normal Inner Layer 1 = Mirrored Inner Layer 2 = Normal Bottom Copper = Mirrored
When viewed from above looking down and through the stack.
TIA
Lately we haven't been declaring CAM planes in PADS. We just do a huge copper pour on, say, layer 2, and attach net name "gnd" to that pour.
That avoids having to deal with keepouts - which often don't work - and allows us to flood over vias. PADS, or at least our version, always places thermals on CAM planes, even if you don't want them. You can cheat and route a little on the "ground plane" too!
The split/mixed plane was always a nightmare in PADS.
CAM plane film comes out reversed, namely mostly clear. Our board houses are fine with that.
What version of PADS are you using? We stuck with v 5.0.
John
Thanks for that John. I'm using PADS2007.
This was a 1.6mm 2-layer board, bottom flooded with GND and no thermals on GND vias until about an hour ago; but I have some (short) traces carrying 1 GHz that really should be 50-ohm and that forced me to use a 4-layer stackup, even though the extra 2 layers are just solid ground and the bottom is 99% ground! My longest 1 GHz path is about one-tenth of a wavelength from a Mini-Circuits VCO to a Hitite prescaler via a resistive splitter and AC coupling cap. This was carried by wider traces (but nowhere near
50-ohms) on the 2-layer version.Have something to add? Share your thoughts — no account required.
Ask the community — no account required