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

Toagosei’s IXE® and IXEPLAS® ion exchangers have excellent heat resistance and ion selectivity, and are used to improve the reliability of electronic materials, such as semiconductor package encapsulants1). In recent years, the switch from gold to copper wire for semiconductor package wiring has accelerated. Copper wire has many advantages over gold wire, including lower cost, higher electrical conductivity, and superior thermal conductivity. On the other hand, copper wire is known to be more susceptible to oxidation than gold wire, resulting in inferior package reliability. Recently, research has been conducted on the reliability degradation mechanism of copper wire packages and countermeasures against such degradation. Some reports suggest that free Cl- ions and the pH level in the encapsulation resin are contributing factors2, 3). We therefore verified the impact of Cl- ions and pH on reliability using copper wiring test pieces instead of copper wire, and assessed the effect of IXE and fine-particle IXEPLAS. To examine differences in scavenging performance based on particle size, migration tests were also conducted by adding IXE and IXEPLAS to the adhesive layer of a flexible printed circuit (FPC) containing copper wiring.