Polyphenylene Ether Macromonomers. Iii. Enhancement of Dielectric Materials

摘要

Two major trends in printed wiring boards electronics are applications that require higher operating frequency, often in the radio frequency range (GHz), and the use of lead free solder assembly. Material requirements for dielectric materials have become more stringent. Key characteristics for dielectric materials are low dielectric constant, low dielectric loss, high use temperature, and low moisture uptake. The use of engineering thermoplastics has been investigated as a means to enhance performance of thermoset resins. In particular, polyphenylene ether (PPE) exhibits excellent hydrolytic stability, low moisture absorption, extremely high glass transition temperature, outstanding electrical properties over a wide temperature and frequency range, and ease of flame retarding without the use of halogenated materials. Investigations on the use of engineering thermoplastics in thermoset resins have pointed out the complexities of the network molecular architecture. Indeed, a wide variety of network morphologies were obtained within the fully cured material. PPE telechelic macromers have been reported as a breakthrough in the search for materials that broadly enhanced performance of dielectric materials. Thus the use of PPE macromonomers as a co-reactant in epoxy resins resulted in extensive performance advantages. Indeed, the use of PPE macromoners in epoxy resins resulted in single-phase networks, exhibited an increase in glass transition temperatures (T_g), lower dielectric properties, lower moisture absorption, and increased toughness. Single-phase matrices were also obtained with cyanate esters that exhibited lower moisture absorption and increased toughness. Vinyl modified PPE macromers were used in resins cured via radical polymerization. These resins exhibited very low moisture absorption in addition to high T_g and very low dielectric properties. The advantages of PPE macromoners in enhancing key properties of various dielectric materials suggest utility in a variety of demanding electronic packaging applications.