Multilayer Ceramic Packages

For multilayer packages, ceramic tape layers are metallized,
laminated and then fired to create the package body. Leads
are then brazed to the package body. The metallized areas
of the package are then electroplated (usually nickel followed
by gold). After assembly, the hermetic seal is achieved
by soldering a metal lid onto the metallized and plated seal
ring. These packages therefore are often referred to as solder
seal packages.
The multilayer construction allows the package designer to
incorporate electrical enhancements within the package
body. For example, power and ground planes to reduce inductance,
shield planes to reduce cross talk, and controlled
characteristic impedance of signal lines have been incorporated
into multilayer ceramic packages.