Good advice given above, I’ll just add that a wider or more blunt tip works better. The larger surface area of the tip allows the heat to transfer faster. Using a fine tip made for SMD work would make it pretty difficult to solder wires on to a copper mcpcb. The copper mcpcb’s require alot more power than the aluminum mcpcb’s in my experience especially if its already mounted to the pill with thermal paste in between. Good flux in the right amount will help.