IEC 61189-5-301:2021 specifies methods for testing the characteristics of soldering paste using fine solder particles (hereinafter referred to as solder paste). This document is applicable to the solder paste using fine solder particle such as type 6, type 7 specified in IEC 61190-1-2 or finer particle sizes. This type of solder paste is used for connecting wiring and components in high-density printed circuit boards which are used in electronic or communication equipment and such, equipping fine wiring (e.g., minimum conductor widths and minimum conductor gaps of 60 µm or less). Test methods for the characteristics of solder paste in this document are considering the effect of surface activation force due to the fine sized solder particles which could affect the test result by existing test methods.