About the mechanical layer in altium PCB
Mechanical layers do not appear on the final PCB. They are used for reference purposes only during the design process, as well as sometimes the setup process at the PCB manufacturer. The pink layer indicates the outline of the 3D body of the chip. This is used so that you, as the designer, can ensure that it does not collide with any adjacent components. The green outline indicates the &quot;courtyard&quot;. This indicates a &quot;bounding box&quot; of the component, plus a bit of a &quot;buffer&quot;. It helps you, as the designer, ensure that there is sufficient spacing around the component (as opposed to simply preventing direct collisions in 3D bodies like the pink layer).