Kester NP505-LT is a no-clean, Pb-free, zero-halogen solder paste with excellent activity, printability and has extremely stable paste properties that is excellent for temperature sensitive substrates and components. - Kester NP505-LT is a no-clean, Pb-free, zero-halogen solder paste for assemblies that have temperature sensitive substrates and components. Warping is becoming more evident with the trend towards complex boards and the trend of using thinner and larger packages and boards. The defects caused by the warpage may decrease board reliability and increase in rework. NP505-LT is designed to reduce warpage inherent to board-to-package.