You can export a SolidWorks assembly from SolidWorks into CircuitWorks. Once in CircuitWorks, manipulate the assembly as needed, and then save it as an IDF file. Use this capability to bring SolidWorks changes back into your ECAD software.
You can also construct a solid model of a circuit board and its components from scratch in SolidWorks, and then export the model so that the electrical information can be added. You might take this approach when a PCB has a complex packaging-driven shape that is easier to define initially in SolidWorks than in the ECAD system.
CircuitWorks uses a series of rules to determine what each SolidWorks component represents, such as a part of the board, a cut-out, or an electrical component. Because IDF is a "2½D" rather than 3D format, CircuitWorks also determines how to simplify the shape of a component so it can be saved as IDF while retaining as much detail as possible. CircuitWorks knows what each SolidWorks feature represents when saving an assembly it originally created (by processing an IDF file). CircuitWorks only needs help identifying features that have been added since it built the assembly or when exporting an assembly that was built from scratch in SolidWorks.