cschem - use cases

The Packaging problem

Setup

• sch -> pcb flow
• generic (light) symbol in the schematics (e.g. a generic IC)
• footprint attribute set to a generic package (e.g. a generic BGA256)

Problems

• the pin numbering of the IC is arbitrary
• the pin numbering of the Package is arbitrary
• a Package+IC doesn't determine the pinout: there are various IC devices with different pinouts with the same footprint
• number of logical pins may not match number of physical pins; unused pins, multiple pins connected, power and ground rings,passive componnents
• Package designers will also use cschem to design the package
• IC designers will also use cschem to design the bonding diagram