Underfill

Ep Silicone Underfill

Application: Flip Chip

A sea island structure, Sunstar’s original polymer technology innovated epoxy formulation for electronics industry. Sea-island structure makes the epoxy resin flexible and hard to crack. It absorbs stress from thermal and mechanical shocks.

Absorbs flux residue left on a PC:

The underfill absorbs flux residue inside and therefore prevents voids from affecting the reliability of underfilled CSP.

Apply flux on to FR-4 => heat 3 min. at 220 degrees => apply UF from above and cures at 150 degrees 30 minutes => cross-section examination

Reparable Underfill

Application: BGA

Features:

  • Low temp. snap cure 500μm layer of the material takes only 1 second to gel at over 70 degrees.
  • Excellent reworkability allows for the easy wiping of the resin residue left on PCB.
  • Excellent electrical insulation
  • Excellent storage stability at 5~10C
  • Excellent endurance for mechanical stress(bending stress)
  • Elastic urethane protects solder interconnects from drop shocks.

Reworkability:

Urethane based underfill, 991 series, eliminates the stressful process of taking the underfilled CSP off and cleaning the material residue off of the PCB. The underfill chemically dissolves after a heat treatment and allows for an easy wiping of little residue left on the PCB, which makes it possible for engineers to analyze a defect device and also to save expensive PCBs.