Water Absorption And Corrosion Protection Of Esterified Novolac Resin Cured Epoxy Resins Applicable For Microelectronics Packing

摘要

Owing to their eminent mechanical and electrical properties, epoxy resins are widely used as structural materials as the packing and coating applications in the microelectronics industry. Because they are often used in a humid environment, and the moisture absorbed in the cured epoxy resins generally degrades the properties of the materials, the behavior of moisture adsorption and transport in epoxy and epoxy based composites received much attention during the last two decades. O-cresol novolac epoxy resin (ECN) cured with phenol novolac resin (NOV) is an important encapsulating material for IC chips. The water sorption of the cured resin (EP) is ca. 2 wt.%. The absorbed water can not only deteriorate the thermal and mechanical properties, the structural stability of the encapsulating material, but also initiate corrosion in the aluminum patterns of the chips. Therefore, resins with low water sorption are strongly demanded for the electronic encapsulating industry. In the present work, to study the effects of side group on water absorption, a series of novolac epoxy resins was cured with esterified a phenol novolac resin and phenol novolac resins separately. Thus, the hydroxyl group of phenol novolac resin was replaced by CH_3COO- group, C_3H_7COO- group and C_6H_5CH_2COO- group, and the cured resins were named as EP, EPA, EPB and EPP, respectively. FTIR showed that there were no hydroxyl groups but ester functional groups in the cured resins cured with the esterified phenol novolac resins. The influence of the side groups on the water absorption behavior of the cured epoxy resins was investigated using gravimetric method, DSC, and corrosion test.