Layer assignment

Layer assignment. Each net sits on a metal layer. Upper layers are faster (lower delay per unit length) but have far fewer tracks; lower layers are slow but plentiful.

• Critical nets meet delay - a critical net's delay is its length times the layer's delay factor, and must be under budget. The long critical nets need the fast upper layers.
• Layers within track count - each layer holds only so many nets, so you cannot pile everything onto the fast layers.

Click a net to move it up a layer. Put the long critical nets high, fill the lower layers with the rest, then Submit design.