Underfill Materials for Flip Chips and BGA Applications
Ep Silicone Underfill for Flip Chip Application
 < Ep silicone sea island structure >
Sunstar’s original polymer technology innovated epoxy formulation
for electronics industry. This sea-island structure makes the epoxy
resin flexible and hard to crack. It absorbs stress from thermal
and mechanical shocks. All our UF materials are based on this unique
structure.
It absorbs flux residue left on a PC
The underfill absorbs flux residue inside and thereby prevents voids from affecting the reliability of underfilled CSP.
<experiment> 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
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Reparable Underfill for BGA Application
Characteristics
1. Low temp. snap cure
500μm layer of the material takes only 1 second to gel at over 70 degrees.
2. Excellent reworkability allows for the easy wiping of the resin residue left on PCB.
3. Excellent electrical insulation
4. Excellent storage stability at 5~10C
5. Excellent endurance for mechanical stress(bending stress)
6. 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.
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