Underfill Epoxy

Category: infrastructure

A specialized adhesive resin injected beneath a BGA chip to absorb physical stress and protect solder joints.

Underfill fills the tight space between the chip substrate and the motherboard. It acts as an anchor that prevents the microscopic BGA solder balls from cracking due to physical board flex or thermal expansion. However, it makes removing or reballing the chip significantly harder for technicians.

Common Examples

• We used a specialized chemical solvent to soften the factory underfill epoxy before attempting to lift the damaged CPU module.
• Scraping away tough underfill epoxy requires an incredibly gentle touch to avoid slicing the fragile traces on the board surface layout.