2. Assembly and interconnection categories

Circuit assembly is the first step after substrate fabrication and cutting. It is defined as the process of electrically connecting the chip's input/output (I/O) pads. Assembly consists of three parts:

• the chip's metal stud,

• a metal connecting element between the chip and its substrate,

• the metal stud on the package.

At the interface between chip and system, this assembly must meet five essential criteria:

• have "acceptable" electrical properties (in terms of capacitance, resistance and inductance),

• be a low-cost solution,

• be easy to industrialize and have a high manufacturing capacity,

• be reliable,...