Underfill is the process of depositing an encapsulant in the gap between two dies or a die and the substrate to improve the reliability and durability of the flip chip assembly making both the physical contact and electrical interconnections more reliable

The underfill encapsulation provides the following benefits to a flip chip assembly.

  • It provides mechanical protection by enhancing the mechanical bonding between the dies or die and distributes any mechanical stress throughout the assembly protecting the conductive balls/bumps.
  • It provides thermal protection by improving heat transfer from the dies to the substrate and provides better heat distribution relieving the conductive bumps/balls of thermal stress.
  • It also relieves mechanical stress from the bumps/balls caused by thermal expansion mismatch.
  • Overall it improves the function, reliability and durability of the flip chip assemblies.

Underfill Work Flow

Material Choice

The choice of encapsulant determines the characteristics of the underfill encapsulation which are tuned to the specific application requirements for the package.

Dispensing at our Facility

At the Advanced Packaging Facility we can precisely and accurately deposit the underfill encapsulations for flip chip assembly. The facility has a robotic 3 axis jetting system with an integrated vision system which is ideally suited to the underfill applications.

At the facility we carefully consider the underfill requirements in terms of target applications of the flip chip assembly, the expected sources of failure and the required characteristics. The encapsulants are selected to match the specifications of the flip chip application. The jetting system allows us the flexibility to use either a one material underfill encapsulation or two material underfill encapsulation.

Arvin Mallari

4236, Building 59, University of Southampton
Highfield Campus, Southampton
SO17 1BJ
Phone: 02380593234