Solder paste characterisation: towards the development of quality control (QC) tool

Purpose
The purpose of this paper is to develop a quality control tool based on rheological test methods for solder paste and flux media.

Design/methodology/approach
The rheological characterisation of solder pastes and flux media was carried out through the creep‐recovery, thixotropy and viscosity test methods. A rheometer with a parallel plate measuring geometry of 40 mm diameter and a gap height of 1 mm was used to characterise the paste and associated flux media.

Findings
The results from the study showed that the creep‐recovery test can be used to study the deformation and recovery of the pastes, which can be used to understand the slump behaviour in solder pastes. In addition, the results from the thixotropic and viscosity test were unsuccessful in determining the differences in the rheological flow behaviour in the solder pastes and the flux medium samples.

Research limitations/implications
More extensive rheological and printing testing is needed in order to correlate the findings from this study with the printing performance of the pastes.

Practical implications
The rheological test method presented in the paper will provide important information for research and development, quality control and production staff to facilitate the manufacture of solder pastes and flux media.

Originality/value
The paper explains how the rheological test can be used as a quality control tool to identify the suitability of a developmental solder paste and flux media used for the printing process.