Toagosei Annual R&D Report “TREND” – Issue No. 28

ARONIX UVX-8032, UVX-8037, UVX-8092 and UVX-8093 are shadow-curable UV adhesives designed for assemblies in which UV light cannot reach parts of the bond line. Conventional UV-curable adhesives can remain uncured under components, in gaps, beneath opaque parts or a black mask, and between overlapped parts, creating incomplete cure, bond failure or insulation failure. This UV adhesive for shadow areas uses radical photopolymerization of specialty acrylates so that, after short UV irradiation, curing progresses from the exposed zone into hidden and hard-to-cure areas.

The system is a one-part, room-temperature-curing and solvent-free UV adhesive that requires no mixing, primer, secondary heat cure or secondary moisture cure. It can therefore be evaluated as a no-heat alternative to heat-curing adhesive and as a faster option for replacing moisture-curing adhesive, supporting short cure time, high productivity and automated assembly of heat-sensitive substrates. It is also compatible with UV-LED equipment. Under the test conditions—black PET, a 0.5 mm adhesive layer and UV-LED exposure of 15 J/cm² at 0.5 W/cm²—shadow curing of 5–20 mm was possible. UVX-8032 and UVX-8037 achieved shadow-cure distances of 13 and 15 mm and are available in different viscosities for coating and dispensing requirements.

The cured materials combine elastomer-like hardness with flexibility; UVX-8032 and UVX-8037 showed elongation of 53% and 60%. In a wire-and-colored-PVC-tube assembly, UVX-8032 cured inside the UV-impermeable tube after 30 seconds of 365 nm UV-LED irradiation, whereas a conventional product remained liquid. UVX-8092 and UVX-8093 provide higher shear strength for glass bonding, metal bonding and polycarbonate bonding, including glass/glass, PMMA/PMMA, PC/PC and SUS/aluminum joints. These shadow-curable UV adhesives may be evaluated for precision fixing and applications involving paper, film, molded plastic parts, medical and electronic components, optical components, lens bonding, optical pickup assembly, optical communication parts and FPD moisture-proof insulation seals.

IXE®-700H is a novel Mg/Al-based inorganic ion catcher developed as an ion-catching agent and inorganic ion scavenger for semiconductor packaging. As electronic devices move toward miniaturization, higher performance, high-density packages and narrow wiring pitch, ionic contamination—especially chloride ions in epoxy resin and epoxy encapsulants—can promote copper electrochemical migration, short circuits and package failure. IXE-700H is a semiconductor package reliability additive designed to suppress ion contamination, prevent ion-related failure in epoxy, and improve the moisture-resistance reliability and humidity reliability of encapsulants.

The white fine powder has a median particle diameter of up to 1.0 μm, heat resistance up to 600°C, and components that are not designated as RoHS-restricted substances. Among existing IXE grades, it offers the highest anion adsorption performance in the neutral pH range. It shows high ion-catching performance over a wide pH range: in water, its chloride-ion exchange capacity was nearly 3 meq/g from pH 3 to 8, about twice that of IXE-700F. This broad-pH ion scavenger therefore works under acidic, neutral-pH and mildly alkaline conditions. In an epoxy-resin extract at pH 6.8, IXE-700H reached 4.1 meq/g versus 1.9 meq/g for IXE-700F. When 0.5 wt% was kneaded into the epoxy before curing, it reduced chloride ion concentration in the hot-water extract by 94%.

In a HAST using 50 μm/50 μm comb-shaped copper wiring at 130°C, 85% RH and 45 V, 0.5 wt% IXE-700H extended the time to the first wiring defect from 34 to 194 hours and suppressed copper-wiring short circuits. These results support its use as an ion catcher additive for epoxy resin, an ion catcher for narrow wiring pitch, an encapsulant additive for fine-pitch packages, and an inorganic ion catcher for advanced semiconductor packages. IXE-700H can also be evaluated for next-generation packaging, power semiconductor encapsulants, 5G semiconductor packages and EV power electronics requiring high durability and improved moisture resistance.