5 Design
5.2 Creating library components

Normally, all PCB design software packages are supplied with a set of libraries. These libraries can be used, modified and added to as required. You can mix and match new and existing library items together to create your own set of libraries.

Before you can make a schematic and subsequent layout of the PCB it is necessary to make sure that you have all the components in a library with their symbol (schematic symbol) and package (footprint for layout).

If not all the components are available, it will be necessary to create your own library and design the symbol and footprint of each missing component. This usually occurs when a new component that has recently been launched on the market is used in the design of the PCB.

For high volume production designs, library quality has a relevant importance. If any created footprint is not 100% well designed and verified with final production site, a big productivity failure can happen, and can have a serious impact directly to the company results. This is a big reason why large companies have their own libraries with an own Librarian exclusive team dedicated only to footprints creation.

Also is very important to have a good 3D design linked with footprint. It allows to make a better product integration (mounted PCB together with mechanical housing).

Fig. 3 Schematic symbol and 3D footprint