Flip Chip Solution
Flip chip derived its name from the method of flipping over the chip to connect with the substrate or leadframe. Unlike conventional interconnection through wire bonding, flip chip uses solder or gold bumps. Therefore, the I/O pads can be distributed all over the surface of the chip and not only on the peripheral region. The chip size can be shrunk and the circuit path, optimized. Another advantage of flip chip is the absence of bonding wire reducing signal inductance.
An essential process for flip chip packaging is wafer bumping. Wafer bumping is an advanced packaging technique where ‘bumps’ or ‘balls’ made of solder are formed on the wafers before being diced into individual chips. ASE has invested significantly in the research and development as well as in equipment for wafer bumping. It has the capacity to bump 6-inch, 8-inch and 12-inch wafers.
Flip chip technology is gaining popularity due to:
Shorter assembly cycle time
All the bonding for flip chip packages is completed in one process.
Higher signal density & smaller die size
Area array pad layout increases I/O density. Also, based on the same number of I/Os, the size of the die can be significantly shrunk.
Good electrical performance
Shorter path between die and substrate improves the electrical performance.
Direct thermal dissipation path
External heat sink can be directly added to the chip to remove the heat.
Lower packaging profile
Absence of wire and molding allows flip chip packages to feature lower profiles.