Toagosei Annual R&D Report “TREND” – Issue No. 19

IXE and IXEPLAS are heat-resistant inorganic ion exchangers developed as ion scavengers for electronic materials and ion-trapping additives for semiconductor package encapsulants. Their low-impurity formulations are free of RoHS-restricted substances, selectively capture ionic impurities such as chloride ion (Cl−) and sodium ion (Na+), and retain captured ions with little release. As an inorganic ion exchanger for resin, epoxy encapsulants, and FPC adhesive layers, they are designed to improve electronic material reliability by reducing ionic contamination that can promote corrosion, electrochemical migration, open circuits, or short circuits.

The study evaluated epoxy/silica encapsulant formulations relevant to semiconductor packaging. In HAST at 130°C, 85% RH, and 40 V for 100 hours, the defect rate increased as extracted Cl− concentration rose and pH fell. Adding IXE or IXEPLAS reduced chloride ions in the resin extract, generally lowered electrical conductivity and defect rate, and improved moisture-resistance reliability. These results support evaluation as an ionic impurity trapping additive, ion scavenger for semiconductor encapsulant, and additive for epoxy molding compound (EMC) formulations where chloride corrosion in encapsulant and copper-wiring reliability are concerns.

Particle size was also critical. IXEPLAS-A2, a 0.2 μm sub-micron ion scavenger, outperformed the 0.5 μm grade of the same composition because its larger specific surface area increased contact with impurity ions. In an 85°C/85% RH, 50 V, 500-hour migration test on narrow-pitch copper electrodes, all tested IXE and IXEPLAS grades suppressed copper migration; fine-particle grades showed stronger migration suppression. Zirconium-based cation exchangers also captured eluted Cu2+, functioning as ion catchers for FPC adhesives and copper-wiring materials. IXEPLAS-A2 is therefore recommended for copper wire packages as a heat-resistant, fine-particle ion scavenger that combines chloride-ion removal, pH control, corrosion suppression, migration suppression, and improved package reliability.