What is Underfill?
Underfill is the application of a fluid along one or more edges of an electronic component, such as a flip chip or BGA type package, that flows underneath using capillary action. Underfill is used to prevent thermal mismatch between the component and the substrate, prevent moisture penetration, and to provide mechanical stability during shock and vibration.
When to Use Underfill
Underfill is utilized when a component cannot meet the reliability requirements of a product. Solder joints that interconnect chips to a board surface can fail or become mechanically fatigued during thermal cycling. Underfill materials provide mechanical reinforcement to solder joints that increase the life of a chip.
Benefits of Underfill
- Provides extra rigidity between chip and PCB
- Helps transfer heat, acts as heat sink
- Dissipates stress throughout the package and alleviates stress on solder balls
- Protects solder joints from mechanical stress
- Improves high-g, thermal cycle, and fatigue cycle performance
- Prevents moisture penetration
