Double-sided copper clad laminate with halogen-free phenolic-resin paper base for lead-free soldering

摘要

While producing double-sided halogen-free phenolic resin impregnated paper base for printed circuit boards, a method has been developed to use each function of the high molecular component and low molecular component of synthetic resin without canceling each other. The double-sided copper-clad laminate board developed has sufficient heat resistance against the higher temperature used in lead-free soldering of component assembly. Meanwhile, it is easy to process and possesses environmental compliance attributes found in conventional material. In an attempt to acquire flame retardant properties with a halogen-free and antimony-free paper phenol base, the authors have developed single-sided and double-sided copper-clad laminate board. They accomplished this by working out the types and quantity of drying oil, amino resin, phosphor-based flame retardant, catalyst etc along with the reaction temperature and time for resin synthesis. However, because leadfree solder has a higher melting point than conventional lead-based solder, the board is required to be sufficiently heat resistant to withstand a higher reflow temperature. Upon reviewing the resin synthesis method, the authors found that the coexistence of the low and high molecular components of the resin was essential. The low molecular component satisfied the reflow temperature heat resistance by improving the penetration into the paper base, while the high molecular component ensured the flexibility and toughness of the resin, thus providing the general characteristics and ease of processing equivalent to the previous products.