The packages can be chosen when the component is placed in the schematic. After placement in the schematic, click on the Package attribute drop down arrow and a list of available packages will be shown. Each of the components has its package pin configuration defined for a package within the Package library. The Package library is controlled by the Package editor which lets the user add or edit the package information for any of the components within Micro-Cap. The Package editor lets you define basic packages and complex packages.
Complex packages are when more than one instance of the component is present within the package.
This editor links the pins used in the schematic to the pins that will be used in the PCB netlist.