This handbook is a companion to the solder paste standard J-STD-005 and should be considered to be a guide to help assess the applicability of a solder paste for its use in surface mount technology (SMT) processes. This document also suggests some test methods that can help with designing and testing solder pastes. It is intended for use by both vendors and users of solder paste. Purpose Solder pastes are unique materials@ whose performance in a surface mount process depends on a variety of variables@ many of them interacting. J-STD-005 provides test methods for classification of solder paste based on the use of a variety of testing techniques. However@ these solder paste classifications do not have a direct correlation to identify the type and characteristics of a specific solder paste that is needed in any given SMT assembly process. This document has been written as a guide to assess the applicability of a solder paste for a specific process@ given the tremendous number of permutations of different materials@ atmospheres and process variables currently available. Where appropriate@ references are given to papers and documents with further information. Due to the sheer number of possible interacting factors@ specific solder paste selection criteria cannot be given. The solder paste selected and the assembly process used will need to form solder connections that meet the requirements of industry standards such as J-STD-001 and/or IPC-A-610.