Process Characterisation using SIR
Abstract
Existing Surface Insulation Resistance (SIR) test methods are outdated and unrepresentative of today’s Printed Circuit Assembly (PCA) process1. A European research programme found that using the existing international standards, the SIR value of a typical no-clean flux could be over estimated by a factor of 10, when compared to a test using parameters representative of today’s technology. Here, in light of these European findings, an updated SIR test method is used to validate the reliability of a PCA process, representative of today’s no-clean technology, including lead-free finish, resist, lead-free paste, water-based flux, lead-free wire and water-based conformal coating.
