SOLIDWORKS/AUTOCAD Plan View Import

Hi all
Here I am with a new problem that is heating up my novice neurons.....:D

I would like to implement a plan view of an assembly made with solidworks on a DWG file on autocad but I encounter several problems:
-When I save my SW drawing in DWG/DXF it is impossible to scale it
-When I want to tinker and save my SW and AUTOCAD as PDF and overlay the two, no scale matches

Is there an easier way to import an accurate view of a SW assembly onto a dwg file (a civil engineering plan)?

Thank you in advance for your precious help!